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Laser Amplifier used at 70%, posted by Ronic Chiche at ThomX igloo about lasers and optics

today, I installed a laser dump just before the telescope to avoid any high power (50W instead of 17W usually) issue in the injection line.
last time, we saw some plastic mounts of the polarizers slightly burnt because of some small misalignment.
I used a thorlabs LB2 (see picture) which is able to manage 80W CW or 25J/cm2 pulses => this is OK in both cases : 50W CW / 1.5µJ/pulse

High frequency noise, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

Today, the lock of the FPC was particularly bad (maybe the worst ever seen), with a lot of high frequency noise.
the lock was impossible during several minutes !

we tried to switch off all the equipments of the machine, one by one without any effect on the lock.

High frequency noise, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

At the end of the day, we found out what was the origin of this noise : some road renovation work with jackhammer and road roller just at the entrance
of the "Igloo".

this origin was 100% correlated with a large increase of the accelerometer signal.

High frequency noise, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

After this observation, we did a test with Daniele to try to correlate the road traffic in front of the Igloo with the lock losses observed on the FPC.
We didn't see any clear correlation. Cars or buses are not the direct origin of the FPC lock losses... only when some heavy load is hitting
the building, we observed a clear correlation.

High frequency noise, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

we did some tests with Marie to make some vibrations on the door.
below, I exhibit some pictures of the scope with the accelerometer plugged on it without or with noise...
this level of noise is not able to make the FPC loosing the lock.

High frequency noise, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

This morning, I installed a high-voltage probe (1:1000) on the AC-line to see if one could detect a correlation between lock losses and AC-line voltage
variations.

I observed many lock losses but without any variation or correlation of the AC-line signal (scope set in "peak detect" with "envelope"

Noise issue, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

since several days, we see that the locking is more and more unstable and the lock duration was sometime less than 20-30 seconds !

1) I tried to optimize the feedback loops

I discovered that the gain on the fast loop on the laser EOM was very low and was almost uneffective for the global stability of the lock (I

Noise issue, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

yesterday, in the same conditions, we had so many locking issues... exactly in the same way than before. :-(
so we still have "locking issues" depending on something we didn't find...

today, we removed the "1/2 voltage divider" before the PZT amplifier to get back the full dynamic.

to anticipate the power shut down on next tuesday 23/09,
this afternoon, I switched off all the equipments except the oscillator connected on the UPS.

this morning, I restarted all the equipments of the FPC.

everything was fine after being able to get back the correct PDH phase between modulation and demodulation...I got 88kW with 33% amplifier ratio
after basic alignment and CEP tuning.

the 33MHz/500MHz RF frequencies from the Ring seems different from the previous state (maybe working at an energy of 50MeV instead of 70MeV which was
the previous energy ?).

so, I let the FPC at the present position and wait to discuss if it is necessary or not to move the FPC motors for the correct energy...

This morning I did a phase alignment on the PDH signal generator (Rigol DG4102)
this procedure ensure that both phases of the sine wave signals are aligned before finding the correct phase for maximizing the error signal.

so, from now on, in case of power shut down, one just need to :

Accelerometer measurement, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

with Daniele, we placed the accelerometer on top of the fiber amplifier box which is inside the housing.
the goal was to try to detect a correlation with some possible accoustic noise coming from the bubbles of the water, cooling the amplifier box baseplate.

we monitored a long trend of the transmission which is perturbated when high frequency noise arises, and the accelerometer signal.

polarization measurement of the FP cavity beam, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

today, with Daniele, we did a simple polarization measurement in transmission of the FP cavity beam.

1) we locked the FP cavity and measured 82.5kw (for 33% amplifier ratio) with the power-meter moved a little bit further (this is maybe the reason
why the power is a little bit lower than usually measured).

Power shut down on August 29th, posted by Ronic Chiche at ThomX igloo about detectors and electronics

This morning, all the equipments have been switched off due to a power shut down tomorrow morning.
Only the Onefive oscillator is still ON, connected to the Uninterruptable Power Supply (UPS).

Power shut down on August 29th, posted by Ronic Chiche at ThomX igloo about detectors and electronics

after alignment, CEP adjustment and optimizing the PDH phase, I got back ~92kW in the FPC for 33% amplifier ratio.

Ronic
Chiche wrote:

This morning, all the equipments have been switched off due to

Alignment correction during the summer break, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

I restarted the FPC system this morning.

after some classic alignement procedure (some LEFT steps on the cavity injection motors X & Y) and CEP tuning,
I got 92kW for 33% amplifier ratio.

laser operation again with machine OFF, posted by Ronic Chiche at ThomX igloo about lasers and optics

The laser start at 33% with 92 KW optimized and

P=0.03

I=0.0005

Xrays experiment with prostate, posted by Ronic Chiche at ThomX igloo about lasers and optics

Today we do XRays for experiment.

The laser start to 33% at 93 KW but Pgain = 0.033

The laser is locked so stable for the moment. We have Xrays and the system is stable.

Suite tests stabilit�, posted by Ronic Chiche at ThomX igloo about lasers and optics

We continue to find what gives high freq. perturbation.

The laser starts at 92 KW it is stable and locked to the RF. NO high freq parturbation.... With the machine off. (30 min of lock)

We put now the machine ON (All in warming exept pulsed elements)... => the system is very stable NO delock, NO high freq perturbations. The

Stability test Without and with , posted by Ronic Chiche at ThomX igloo about lasers and optics

The laser starts at 93 KW.

This morning I operated the laser locked with the RF for 1h30 without any delock. All the machine was switch off.

All the system was very stable. Sometimes the 20 Hz perturbation was visible but no delocking.

Tuning of the slow feeback loop analog BW + fast feedback loop gain + PID, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

Today with Daniele, we tuned the potentiometer after the Laselock which drives the analog BW of the PID on the laser PZT,
and we tuned also the fast loop gain (with the rotary potentiometer dedicated to it) => the PID parameters have changed.

so, the recipies has changed => to be updated

New recipies with additionnal attenuation before the diffuser, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

With optical attenuation only

For ~ 92kW power in the FP-cavity:

Alplhanov amplifier ratio : 33%

New recipies with additionnal attenuation before the diffuser and new x3 amplifier on laser PZT, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

With optical attenuation + x3 amplifier on laser PZT channel + feedback tuning

Temporary recipie for ~ 92kW power in the FP-cavity:
(in the previous scheme, without x3 laser PZT amp, a good lock was achieved for a PDH signal power noise ~ 70 mV rms)

laser PZT amplifier, posted by Ronic Chiche at ThomX igloo about detectors and electronics

this afternoon, I added the Gain = 2.8 amplifier at the output of the Laselock to drive the laser PZT.
the power supply of the board is disymetric to address the correct maximal dynamic range of the amplifier (~ 30V) and voltage drop (~ 2V) related
to the power supply voltage.

long run to test the appearance of high frequency noise, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

Today with Daniele, we did 6 long runs at different power (23kW, 46kW, 66kW, 73kW, 92kW, 92kW)

All the lock loss in between these several runs are due to FPC locking parameters change.
most of the few lock losses during the stable power duration, are due to 20Hz oscillation noise or because we forgot to center properly the PZT

long run to test the appearance of high frequency noise, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

today, long run directly at full power (33% amplifier ratio) => 98kW in the FPC at the very begining of the run.
(P=0.05 / I=0.0005 / D=0.6)

10-40 min : almost misalignment effect (CEP did not change so much)

optical attenuator added on the diffuser + new PID parameters, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

Today we did several long runs (~1h each) at ~23kW, 46kW, 66kW with different PID parameters which seems better.

P = 0.1
I = 0.0015

Recipies for different FPC power, posted by Ronic Chiche at ThomX igloo about lasers and optics

For ~ 46kW power in the FP-cavity:

Alplhanov amplifier ratio : 20%

Axis 18 position : -0004710 steps

Recipies for different FPC power, posted by Ronic Chiche at ThomX igloo about lasers and optics

For ~ 23kW power in the FP-cavity:

Alplhanov amplifier ratio : 15%

Axis 18 position : -0016014 steps

Recipies for different FPC power, posted by Ronic Chiche at ThomX igloo about lasers and optics

For ~ 66kW power in the FP-cavity:

Alplhanov amplifier ratio : 25%

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

the RF frequency changed from 500.1003MHz to 500.0913MHz => it reduced by 9kHz @ 500MHz which is equivalent to 600Hz @ 33MHz (we measured 500Hz @
33MHz). the electron orbit length increased, so we have to increase the cavities length => increase motor values by ~ 68µm.

for the laser cavity : 1.496 560 mm => 1.564 560 mm

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

at the begining of the day, we started to get ~81kW in the FPC for 33% amplifier ratio and after ~1h, we got 84kW after CEP and alignment tuning.
at the end of the day, we got 89kW without walking alignment.

we tried to improve a bit the robustness of the FPC and RF locks:

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

today with Alice, we planned to do a long run with ~80kW in the FPC to check if the lock problems are coming from the interaction with the machine or
not.
the goal is to check this assumption on a full day comparable with a day of X-ray production.

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

we observed that :

- the MOT.03 motor always exhibits some perturbations on the transmitted, reflected and PZT signals (see "peaks" in the picture) in
contrary to the MOT.06 motor.

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

last thing we tried :

we removed the threshold on the FPC/RF error signal.
=> we cannot choose automatically the RF bucket anymore (we need to manually let the phase drift slowly and start the lock at the right moment).

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

This morning, I added an amplifier on the 33MHz beating signal in between the mixer+LPF and the scope/Laselock.

it seems to improve the robustness of the RF/FPC lock.

because of this gain, I increased the upper and lower thresholds on the search criterion of the RF/FPC lock from +/-50mV to +250mV/-200mV

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

major result of the day: X-ray vertical scan by moving the hexapod

abscise : hexapod position
ordinate : xray flux in asynchronous condition

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this morning, Kevin reduced the steering current in the IcePap controllers of the FP cavity motors.

the motor MOT.06 was producing a pattern in the Transmission signal when it was moved and doing a lock loss very often.
so, we changed its current from 0.8A to 0.4A and it fixes the problem => no more systematic lock loss.

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this morning, I restarted the cavity after the Christmas shutdown.
everything went fine.

I got ~ 86kW for 33% laser amplifier ratio after optimization of the CEP and alignment with walking procedure.

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

today we did x-rays => we got 41 000 pA at maximum and 90kW in the FPC for 33% amplifier ratio.

finally, I changed the strategy for the feeback on RF.
i removed the integration and derivative parameters and reduced the gain parameter :

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this morning, I restarted the lock of the CFP after almost 2 weeks without operation.
after quick alignment and CEP tuning, I got 88kW for 33% ratio for the laser amplifier.

the FPC seems pretty far from the RF frequency (2.8kHz @ 33MHz) but it's possible the present RF frequency has been tuned for 61.5 or 70MeV

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this morning, the cavity was pretty misaligned => basic alignment in y direction helps a lot => 93kW for 33% amp ratio.

the Rigol 33MHz generator phase was adjusted : phase ch2 = phase ch1 (40 deg) + 36 deg = 76 deg.

Ronic

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

today, the alignment of FP cavity was so bad that I tuned the 01 mode by error (CEP and alignment)... insead of the 00 mode !!!
I was able to reach ~30kW and was limited at this value, so I used the camera to check what was happening and saw the 01 mode.

so, I moved the lock on a 00 mode and redid a full tuning (CEP and alignment).

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

today, after 1 week of vacation, I was able to easily lock the cavity with 92kW with 33% amp ratio without too much optimizations (no walking alignment).

could it be related to the nice weather we got during this week ?
as in the past we observed more noise when the weather was changing and we had very difficult locking procedure after a simple weekend...

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

Today, I removed the NKT oscillator from the bunker to put it in the PLIC room.

I locked the FP cavity and obtained 97kW with 33% amplifier ratio, without any alignment, just by changing a little bit the CEP.

Ronic

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

New locking parameters (I got 98kW for 33% amp ratio) :

Axis 18 position : +0009420
P = 0.05

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

We had a long run without any lock loss during ~1h with the 23kW recipie in the morning.
during the afternoon, we had some few lock losses but the FPC system was globally quiet and stable,
but at the end of the day, I observed more and more frequent high frequency noise which implies lock losses.

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

long run yesterday at relatively low power (~23kW) with double loop (FPC + RF) between 10am and 6pm

Ronic
Chiche wrote:

We had a long run without any lock loss during ~1h with the 23kW recipie

day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

long run today at relatively nominal power (~90kW) with double loop (FPC + RF) between 13:30am and 6:30pm

Ronic
Chiche wrote:

long run yesterday at relatively low power (~23kW) with double loop

Possible causes for the noise in the FP-cavity system, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | vacuum | detectors and electronics

list of possible causes of the high frequency noise which makes the system loosing the lock => to be checked.
(if you have some new idea, I will edit the post)

1- Laser

Possible causes for the noise in the FP-cavity system, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | vacuum | detectors and electronics

4.3 - Vibrations of the mirror mounts due to temperature related to cavity power (the electrons machine is OFF)

1) to test this possible issue, we plan to make a run at low power in the FP-cavity, around 10kW, instead of ~90kW as usual.
for that, I will need to change the diffuser position on axis 18 to get the same error signal for the locking.

New power record in ThomX cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics

today, we were able to store more than 93kW in the FP cavity, always with the same parameter : 33% laser amplifier ratio

New power record in ThomX cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics

today, we were able to store more than 94kW in the FP cavity, always with the same parameter : 33% laser amplifier ratio

Ronic
Chiche wrote:

today, we were able to store more than 93kW in the FP cavity, always

New power record in ThomX cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics

today, we were able to store more than 95kW in the FP cavity, always with the same parameter : 33% laser amplifier ratio

Ronic
Chiche wrote:

today, we were able to store more than 94kW in

New power record in ThomX cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics

today, we were able to store more than 97kW in the FP cavity, always with the same parameter : 33% laser amplifier ratio

Ronic
Chiche wrote:

today, we were able to store more than 95kW in the FP cavity, always

New power record in ThomX cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics

yesterday, we were able to store more than 98kW in the FP cavity, always with the same parameter : 33% laser amplifier ratio

Ronic
Chiche wrote:

today, we were able to store more than 97kW in

33MHz phase adjustment, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software

the 33MHz beating signal (phase) is used to start and stop automatically the lock on the 500MHz beating signal.

this 33MHz beating phase has a fixed range (typically +/-0.5V), so it is important to center this beating phase in the middle of its own range
when the 500MHz signal is locked

air conditionning in ThomX Bunker, posted by Ronic Chiche at ThomX igloo about lasers and optics

The temperature slitly increase in thomx Bunker from 23° to 24° during the last day.

The thermalisation of the CFP is very long...

In any case the operation of the CFP is so easy, it seems to be correlated to the weather... tody it's very nice as of hte rest of the week.

air conditionning in ThomX Bunker, posted by Ronic Chiche at ThomX igloo about lasers and optics

after the new temperature setting for the bunker air cooling (winter to summer transition), the temperature drop from 24° to 20°C which induced
a slight misalignment between the onefive oscillator and the fiber injection.
the amplifier photodiode PD_IN which checks the amplifier power injection drop also from 3mW to 2.885mW... hopefully, it is enough to start the

air conditionning in ThomX Bunker, posted by Ronic Chiche at ThomX igloo about lasers and optics

I finally got 93-94kW for 33% amp ratio.

I had to move the FP-cavity length to compensate the temperature change in the bunker.
doing that, I had the message "Low Limit SW pressed" when I tried to move P4z under -98 000 steps !!!

Electrons-Photons phase stability measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

we installed a measurement at the IP with the BPM for ion cleaning for electrons and we used a fast photodiode at the output of the FP-cavity and measured
with a fast oscilloscope the phase jitter between the 2 signals.
in red, the BPM signal

Electrons-Photons phase stability measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

the phase between the 500Mhz ring RF oscillator and the electrons is measured on a BPM and is very stable after 2-3ms (<< 6ps, typically) !

in the same time, we can use the residual phase beating after our 500MHz mixer to estimate the phase noise coming from the laser part.
the rms noise of this signal is around 60mV for 1.25V peak (2.5 pk-pk) signal => ~ 50mrad rms

New direction for cavity motors, posted by Ronic Chiche at ThomX igloo about mechanics | software

from now on, one reverts the FP cavity motors direction to compensate the long drift from the begining of the project.
the motor MOT.06 will be used for the upward direction (presently -1 082 650 steps)
and the motor MOT.03 will be used for the downward direction (presently +37 170 steps)

Good Xrays production trend, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics | software

this afternoon, we succeeded to get a quite long Xray production trend around 15-20 minutes with a flux above 25k on i1.

strange drift (new effect !?!), posted by Ronic Chiche at ThomX igloo about software

today, we had a strange effect :
both the laser and the FP cavity were locked on the RF frequency (500.10045 MHz), and we were producing X-rays but with a slowing (several seconds)
fluctuation exactly as the electrons-photons phase was drifting and the fluctuation can goes to 0 Xrays produced even at the "right" phase.

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

I installed an accelerometer setup in the bunker.
presently, the accelerometer is placed on top of the housing and its signal is connected to the 2nd scope (33MHz and 500MHz RF beating) on channel
4.

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

today I connected a copy of the laser PZT signal to the 2nd scope CH2 (with AC coupling to remove the DC offset) to be able to monitor synchronously
the Accelerometer and laser PZT signals.
the accelerometer is still connected to the 2nd scope CH4 and placed on top of the housing.

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this morning, I did some measurement with nobody interfering with the tests.

- the "no noise" image shows a standard situation during 10s when there is no noise either on PZT or Accelerometer.
most of the time, we are in this situation.

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics 8x

then, I moved the accelerometer on top of the "X-hutch side" vessel, placed directly on the metal top case, inside the housing.

- the "no noise same range" image shows a standard situation during 10s when there no noise either on PZT or Accelerometer.
on can compare the noise level on the accelerometer with the previous post when it was outside on top of the housing.

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

at the end of the day, I moved the accelerometer from the top of the cavity vessel to the top case of the Onefive laser.

I quickly saw again quite strong correlations between the vibrations compensated by the PZT and the accelerometer signal.
when one does a laser motor step which makes a systematic lock loss, one doesn't see any signal on the accelerometer.

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics 6x

this morning, I did some new plots with the accelerometer placed on the top of the case of the OneFive laser.
I previously observed with the accelerometer placed on the top of one cavity vessel, the correlation between the accelerometer signal and the PZT
noise is pretty good but not 100%.

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics 7x

new plots, with the accelerometer placed directly on the optical cavity table (on the marble part), close to the oscillator.
the correlation seems a bit better....

we would need to put the accelerometer on one foot of the table to check if the table has not some micro-movement or at the IP to check if the

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

one possible source for this acoustic noise was the vibrations coming from the water cooling of the dipoles which is normally never turned off even when
the machine is off.

this afternoon, Kevin turned off the main valve of the water cooling of half of the dipoles (the half on the FPC side), and we recorded the peak-peak

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

here is the pk-pk measurement of the accelerometer during the whole night.
the recording started at 5pm yesterday and has been stopped this morning at 10am.

one got 28k points in 17 hours => 1.65k points / h

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

here is the acquisition from 10:30am to 5:30pm

11k point in 7h => 1.57k points / h

the noise is almost the same during the daylight, a little bit increasing from 1:30pm.

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

here is the same kind of measurement (pk-pk of 1 sec of acquisition) done on the laser PZT when the FP is at 90kW.
it's from 6:20pm to 7:10pm => ~2.4s by point

the minimum values are for the PZT being off.

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

long term pk-pk measurement of the accelerometer (placed on the optical cavity table, on the marble part close to the laser oscillator) from 5:30pm to
9am => ~ 2.255s / pt

start of the quiet period : ~ 5k pts <=> 8:45pm

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

I installed the accelerometer on the ground close to one feet of the FP cavity hexapod (see picture) and restarted the acquisition at 6:40pm on 20th
of february.

the acquisition corresponds to the night between the 20th and the 21th of february.

correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

for this 20Hz oscillation, could it be a natural resonance of the optical table placed on its feet ?

typical mass of the table m ~ 8T

feets :

correlations between vacuum gauges and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | vacuum

the machine people saw a correlation between BPM jumps and vacuum gauges peaks related to breakdowns in the beam pipe.

these breakdowns could produce some accoustic noise which could be related to our lock losses.

=> we tried to do a corrrelation between our lock losses and the vacuum gauge peaks => WE DON'T SEE any correlation !!!

CEM noise measurements, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | cabling

The goal of these measurements is to check if one can find some correlation between the CFP lock losses observed during a run and some CEM noise in the
bunker.
the main issue is coming from a 20Hz noise apearing/disapearing in the laser cavity PZT signal.

CEM noise measurements, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | cabling

This afternoon, we started almost all the parts of the machine with Vincent and Nicolas, and we didn't see any change in the Loop noise signal.
we saw only a peak comb at 10Hz on the Loop noise signal when the septum is ON. the amplitude of the peaks is then related to the voltage on the
septum.

Checking the amplifier power, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

this morning, with Daniele, we checked the amplifier power, right after the CVBG (the power meter has to be placed on a metal plate above the large table
hole), and just at the input of the FP cavity, after the 1/4 and 1/2 waveplates (the power meter has to be placed on flat beam dump+ Thorlabs beam dump
+ V metallic mount to be at the right height).

Checking the amplifier power, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

we did a long term run (25 mn) with the powermeter located at the FPC position at 33% amplifier ratio.

the initial power was 18W .
then, it goes to 18.5W in 10 minutes, then 5 minutes later, it goes to 18.3W and stay stable until the end the run.

Checking the amplifier power, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

I put back and aligned the 1/2 waveplate only and I get 71kW max after its optimization and optimizing the CEP and alignment (without walking procedure).
this waveplate change a lot the reflected power seen on the CH2 of the scope.

to be continued this afternoon...

Checking the amplifier power, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

this afternoon, we put back the 1/4 and 1/2 waveplates and after a long alignment/angle tuning/CEP optimization process, we hardly got 80-81kW in the
cavity for 33% amplifier ratio. the transmission photodiode is then ~ 7.5 divisions (500mV/division) on the scope.

BUT during the 1/2 and 1/4 waveplate angle tuning process, we clearly saw:

Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

here are the (good) lock parameters used this morning.

for the RF/FPC lock, the 33MHz beating signal used to select the right bucket is 1Vpp
=> beating signal : V0 . sin(phi) with V0=0.5V.

Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

Today with Daniele and Alice, we operated to cavity.
we obtained 84kW for 33% of amplifier ratio.
we had to tune the CEP @ -565µm and the FP-cavity alignment.

Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

This morning, I wanted to test quickly if the Smaract motors can be used in open loop instead of closed loop or in piezo scan.

the goal is to do very fine steps without to much vibrations (like with piezo scan mode) but with the full motor range (the piezo scan mode
has a very limited range).

Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

This afternoon, we scanned the optical table vertically with the hexapod in asynchronous mode to find its optimum position, looking at the X-ray production.
then, we searched for the correct bucket and phase in the bucket thanks to the Kevin script on the 500MHz and the 33MHz phases.

we got relatively easily some stable X-rays.

Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

Today, after setting the locking parameters, I got 80kW in the FPC for 33% amplifier ratio after CEP tuning (Smaract CH2 ~ -423.5µm) and alignment.

maybe the alignment has to be improved by some walking procedure.

Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

this morning, I did some walking procedure and I got 82kW in the FPC with 33% amplifier ratio (after CEP optimization too).
but when I move the FP cavity motors to adjust the frequency, I cannot keep this power and it is reduced.
could it be we get a stronger correlation between axis than before in the mechanics has more rust than before ?

Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

this morning, I did some walking procedure and CEP alignment to get ~80kW in the FPC with 33% amplifier ratio.

we have to check if this power drop comes from:

- a laser amplifier power drop

Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

the RF frequency is now 500.1003MHz which is equivalent (if divided by 15) to 33.34002MHz.

the frequency has to be changed by ~2kHz @33MHz <=> ~550µm /2 for one motor.

I changed the laser and the FP cavities frequency.

Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics

On Friday 11th of October, due to the Yvette flooding, all the AC power of ThomX have been shut down.
After the shutdown, I had to restart the Onefive oscillator but the laser modelock was lost.
I had to do a step of 1mm at 10mm/s with the Smaract motor on the rep rate channel (CH1)

Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics

This morning, I verified the reason why the seeder frequency was not displayed on the amplifier software screen:

one needs to start the amplifier (even at 0%) to see the seeder frequency !!!
now, we have 33.371MHz as expected ! => OK

Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics

After the new Yvette flooding of the last week and the consecutive AC-shut down, I restarted this morning the laser with the same procedure (step of
1mm at 10mm/s with the Smaract motor on the rep rate channel (CH1)).

now, we have again 33.371MHz and 3.1mW input power as expected ! => OK

Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics

For the modulation/demodulation generator for the PDH signal,
after a power shutdown, on can :
1) restart the generator to get the correct parameters:

Characterizing Focus Tunable Lens, posted by Fatematuj Johora at Optical room about lasers and optics

Yesterday Ronic and I worked on the high laser power measurements with the Vertical set-up of the Focus Tunable Lens. We went upto 38W@4 dpt at the begining
and then also changed the focal power at 38W.

Observation:

Finding correct motors position and parameters to keep the lock during a move, posted by Ronic Chiche at ThomX igloo about mechanics

this morning, I try to find a new region for MOT.03 and MOT.06 where we can move them without unlocking the cavity.

I started from the position:
MOT06 : ~ -785 000

Finding correct motors position and parameters to keep the lock during a move, posted by Ronic Chiche at ThomX igloo about mechanics

this morning with Daniele, we did a quite long run with this motor position and it seems we don't lose the lock too much.

the motor positions are:

MOT.03 (M4): -186 500 steps

restarting CFP system after the long summer shutdown (RF section conditionning) and Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software

temperature in the casemate ~ 19.5°C stable

this morning, I measured the power directly at the output of the fiber coupler (through the output fiber), after the strecher : ~5mW
then, I connected the EOM used for the PDH technic : ~2.5mW

I refilled the chiller and the stabilized temperature is @ 25°C

we started the 3rd stage of the Alphanov amplifier at 30% => PD_OUT is fluctuating around 1-1.4W => it's not related to the real output
power !

we had to move the laser cavity motor to find the resonances and change a lot the CEP.

the CEP motor is at -524.1µm

we got ~75kW in the FP cavity without alignment but with CEP optimization.

after doing some alignment (walking procedure on the Y axis), and CEP optimization, I got 83kW for 33% on the laser amplifier with a coupling of ~60%

=> we have to check the input power after the amplifier.

I adjusted the FP and laser cavity motors to have a small 33MHz detuning with the RF reference (~10 Hz of beating @ 33MHz)

this morning with Daniele, we are measuring the amplifier power just before the FP-cavity.
Casemate temperature @19.5°C

@0% : 205mW

After the summer power shutdown, I restarted all the equipements and got quickly ~80kW for 33% amplifier ratio with CEP optimization and without Alignment
optimization.

CEP motor position : -506µm

amplifier power measurement before the compressor CVBG.
we used a mirror in between the amplifier output and the compressor + a 2-mirror periscope to match the powermeter height.

amp ratio (%) power (W)

after redoing the alignment of the CVBG, we got back the initial power in the FPC (87kW)

now, I checked the RF locking signals on the 2nd oscilloscope.
I get a strange ratio between the 33MHz beating and the 500MHz beating signals.

now, the Ring RF frequency is set to 500.067MHz.

so the CFP/laser frequency should be 500.067MHz/15 = 33.3378MHz.

the frequency was set to 33.378MHz !!! => it explains the frequency shift only on the 33MHz beating => I corrected the frequency on the

I changed a little bit the locking parameters (see picture) for the RF/FPC loop and it locked rapidely.

I asked Vincent to connect on the same scope the synchro signals to check if the FPC lock was OK => he connected 33MHz signals coming from
the laser and from the 33MHz RF generator.

this morning, with Vincent :

- we added the 10Hz trigger to the CH2 on the remote scope (192.168.229.21) to check the synchronization at the right timing.
CH1 : 33MHz RING

20Hz oscillation in the locking between Laser and FP-cavity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this morning, we tried to find the origin of the 20Hz oscillation.

- we switched OFF the laser Smaract motors controller => no change

- then, we addionally disconnected the FP-cavity PZT cable from the Laselock (we put a charge of 1kohm) => no change

20Hz oscillation in the locking between Laser and FP-cavity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this afternoon, we did 2 tests to better understand this 20Hz oscillation:

- we locked the amplified laser directly to the 500MHz ring reference oscillator, without any intermediate locking to the FP-cavity => no
change

20Hz oscillation in the locking between Laser and FP-cavity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

yesterday I did 2 tests to try to understand the origin of the 20Hz oscillation which is dominant in the remaining 10-20ps rms jitter between the transmitted
pulses and the RF reference generator.

10ps rms jitter is equivalent to phase jitter dphi = 2*pi*f0*dt = 2mrad rms @ 33MHz or 30mrad rms @ 500MHz.

20Hz oscillation in the locking between Laser and FP-cavity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

what does this 10ps phase jitter mean in term of cavity length variations ?

L = L0 + dL sin(2pi fm t) = L0 (1 + dL/L0 sin(2pi fm t))

F = c / L ~ F0 - F0² dL / c sin(2pi fm t) with F0 = c / L0

20Hz oscillation in the locking between Laser and FP-cavity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

measure to be done next week to check the 20Hz noise on the laser amplifier signal:

- install a DET10 in reflection of the FP-cavity to get a high BW and measure the 500MHz harmonic.
- do the beating with the 500MHz Ring RF generator

20Hz oscillation in the locking between Laser and FP-cavity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

could it be possible this 20Hz oscillations comes from anouncements in the bunker, puting the housing+table in vibration ?
(there are such anouncements during restricted access) => to be asked to Harold

Ronic

fixing CVBG issue, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

the CVBG of the compressor module seems to have an issue.

here is the plan of the work :

1) faire des résonances avec la CFP

fixing CVBG issue, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics 12x

1) this morning, I aligned to CFP to get back 82kW in the cavity for 33% of amplifier ratio.
thus, we can ajust the iris positions on the optical table to fix the CFP optical path before touching the CVBG.

2) we aligned the 5 iris. all of them were misaligned by 1-2mm, principaly vertically (maybe because we had to change the CFP frequency some

fixing CVBG issue, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

this morning with Daniele, we realigned the amplifier beam axis on the iris position.
it was pretty fast an easy => we got rapidely some resonance and we locked back to 87kW @33% amp ratio after tuning CEP and alignment.

we tried to play on the L-shape but we didn't a clear effect.

Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics

on Monday morning 7/11, we tried to restart the Alphanov amplifier which was not turned on since end of april 2022, but it didn't start.

we did a standard "turn ON" procedure :
- check the safety button on the front panel (which has to be released).

Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics

I just tested the fuse inside the black ON/OFF switch on the rear panel => it is OK ! :-(

Ronic
Chiche wrote:

on Monday morning 7/11, we tried to restart the Alphanov amplifier

Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics

The laser amplifier controller has been sent yesterday and received today by Alphannov.

they should do the assessment quickly...

Ronic

Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics

Today, I did a Teams meeting with Guillaume.
He didn't see any problem with the controller.
normally, the controller will be shipped to the lab tomorrow.

Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics

Yesterday, we received the controller back from Alphanov
and I tested it immediately in the optical room.
if the software is properly talking to the controller, everything works normally.

Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics

FYI : to access special menus on the Alphanov software,

login : "Administrator"
pwd : no password

Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics

the present situation is :

Guillaume asked me to disconnect the "Laser head" cable from the pump diode module, installed on the optical table.
on the pump diode module, the connector has several small pins and 3 larges pins : A1, A2, A3.

Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics

Guillaume and Julien Bour from Alphanov will come on wednesday 24/07 to have a first look and check the amplifier.

to prepare their intervention, I tested this morning the OneFive oscillator : it's still working at 33MHz.
and we have ~5mW in the LAL software without the EOM.

Alphanov amplifier issue, posted by Ronic Chiche at ThomX igloo about lasers and optics

picture of the connectors used to carry signals between the amplifier pump module and the rack under the table.
DB13W3 standard has been used to carry high current on the 3 dedicated pins:

https://en.wikipedia.org/wiki/DB13W3

New password for login on the ThomX computer, posted by Ronic Chiche at ThomX igloo about software

the previous password has expired.

the new access from the computer :
login : .\$jehanno

FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

This morning with Daniele, we operated the FP-cavity to be sure there is no issue due to the Linac section changing operation :
- opening/closing the valves due to air pressure break down
- opening/closing the bunker roof

FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

This morning, I locked again the FP-cavity at more than 50kW with 33% of laser amplifier ratio.

the temperature is measured today at 20.5°C despite the fact the air conditionning is still OFF.
the temperature, rising from 18°C, started monday at 11AM roughly.

FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

from now on, the transmission factor for calculating the FP intra cavity power is 1/1.75ppm ~ 570 000 (changed in the Powermeter software)

this morning the temperature of the water cooling circuit is still very high said Sophie, and the laser amplifier temperature "Temp Amp1"
is at 29°C instead of ~23-25°C

FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

this morning, I had to restart the chiller. Temp Amp 1 is at 27.5°C after having started the amplifier at 33% ratio.

I removed the 100kohms resistor on the Transmission channel, on the scope (now, it is 1Mohms), to get more sensitivity.

the air temperature is around 21°C and is stable during the last days.

FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

this morning, the computer was restarted and I had to launch all the applications.
no problem except the powermeter for which I had to do a power switch OFF and ON remotely.

the chiller was in error and I had to restart it also.

FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

this morning, the chiller was in error and I had to restart it.

the air temperature is around 21°C.

FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

Yesterday, the ThomX water circuit should have been repared,
and yesterday aftenoon, Daniele restarted the chiller and I checked it this morning without any error.
BUT the pump of the ThomX water circuit is again in default...

FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

the air temperature is between 21°C and 22°C.

I tried to lock the cavity but it was very instable with only short time locks.
I had to increase the parameters of the PID:

FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

today, I tried to restart the amplifier at 0% (without 3rd stage) but it didn't start... still the same error message.

but the PD_IN power and the PD_PULSE frequency seems correct.... I will try to power the amplifier OFF and ON later to see if one can reset this
error.

FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

today with Daniele, we disconnected the EOM to increase the injected power of the amplifier, we were at 4.8mW but we still have the "bad sequence"
error => email to Guillaume
we tried also several time again, to stop and restart the amplifier, but it didn't help.

New multiplication factor for the Fabry-Perot intra-cavity power, posted by Ronic Chiche at ThomX igloo about lasers and optics

last week, we measured the transmission of a plan mirror from the same batch than the ThomX mirrors and we got ~ 1.75ppm instead of 3ppm which was the
calculated value by the LMA.

previously, we put 1/3ppm = 333 333 as multiplication factor.

correct parameters for locking the FP-cavity, posted by Ronic Chiche at ThomX igloo about software

Today, we restarted the FP-cavity locking, after 3 weeks without using it.
those 3 weeks have been used to set the machine ring at the new (better) frequency : 500.067MHz (corresponding to a change of -183kHz)
or 33.3378MHz in fondamental frequency (corresponding to a change of -12.2kHz)

correct parameters for locking the FP-cavity, posted by Ronic Chiche at ThomX igloo about software

this morning I solved the problem of the 33MHz frequency beating which should be ~12kHz between the generator (at the new frequency 33.3378MHz) and the
laser cavity frequency (still at the old frequency which is 33.35MHz)...
the generator providing the 33MHz frequency has 2 channels, and only one was set at the proper frequency !

correct parameters for locking the FP-cavity, posted by Ronic Chiche at ThomX igloo about software

this morning, I finished the FP-cavity alignment with the new ring RF frequency.
I get back 50kW @ 33% amplifier ratio.

I'm also able to lock very smoothly on the 500MHz ring RF frequency.

Laser and FP cavities frequency adjustment, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

at the beginning of the procedure, the frequency gap between the new Ring 33MHz frequency (33.3378MHz) and the laser/FP cavities frequency was 12.33kHz
=> the Smaract motor position was at +100µm
=> the FP cavity motor Mot.03 position was at -358 720 steps

Laser and FP cavities frequency adjustment, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

This afternoon, I did the 2nd half of the travel: dF @ 33MHz = 0Hz
=> the Smaract motor position is now at +1750µm
=> the FP cavity motor Mot.03 position stayed at -200 000 steps

lock oscillateur 33MHz - synth� 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics

pour préparer le lock cavité-anneau, j'ai un setup de lock en salle optique entre le laser OneFive 133MHz et un synthé à
533MHz (133MHz x4).
ce matin, j'ai pu locker les 2 ensembles avec le laselock avec une stabilité RMS, je pense inférieure à la ps.

lock oscillateur 33MHz - synth� 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics

régler le problème 1:
Kevin m'a apporté un déphaseur Minicircuits JSPHS-661 (400-660MHz / 180° de phase) qui permet de déphaser le 500MHz
de ~ 1ns avec une tension DC 0-10V.

lock oscillateur 33MHz - synth� 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics

Today, I installed a DB9-DB9 female-male cable on the PZT connector of the FP-cavity.
the PZT is connected between pins 1 and 2, with a capacitance around 70nF.
I need to make a prolongator cable BNC-DB9 female to connect it to the feedback system.

lock oscillateur 33MHz - synth� 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics

Today, I connected the BNC-DB9 female prolongator cable to the FP-cavity PZT cable (DB9-DB9) and to the channel B of the Laselock.

I additionnaly connected the reflected laser beam (normally connected to scope ch2) to the spectrum analyzer @ 1GHz to observe the 30th harmonic
of the laser comb.

lock oscillateur 33MHz - synth� 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics

this afternoon, I installed the frequency detection scheme in the bunker :

- I changed the large reflected photodiode DET100 by a fast small DET10.

- a 50ohms splitter is connected to the photodiode :

lock oscillateur 33MHz - synth� 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics

this afternoon, I tried to lock the FP-cavity on a local 500MHz synthesizer as a frequency reference
(it's faster to change the frequency from the sythesizer than from the FP cavity !!!)

I found some parameters on the PID of the Laselock to phase-lock the reference and the FP-cavity

lock oscillateur 33MHz - synth� 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics

this morning, I added a Thorlabs lowpass filter at 1kHz after the mixer and a resistor at the Laselock output to the FP-cavity PZT.
I set the PID with P=10 and I=D~0

in attachement, a plot of the 500MHz mixer output, before and during the lock.

lock oscillateur 33MHz - synth� 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics

this afternoon, I firstly connected the HV output of the Laselock to the FP-cavity PZT : https://elog.lal.in2p3.fr/FPC/THOMX+commissioning/248

locking the FP-cavity on the local synthesizer works better with the improved HV output range.
the ~20Hz oscillation in the beating signal of the FP-cavity/synthesizer is still there.

lock oscillateur 33MHz - synth� 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics

this afternoon, we were able to lock the laser on the FP-cavity and the FP-cavity on the Ring reference oscillator in a same time from the control room.

the procedure when laser, cavity and reference oscillators are far in frequency, is :
1) start the amplifier to get the laser signal in the reference photodiode used to measure the 33MHz.

lock oscillateur 33MHz - synth� 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics

after a sudden FP-cavity Finesse increase, we had to install the Fast Feedback Loop in order to continue to lock the cavity.

this afternoon, I was able to lock both the FP-cavity and the Laser on the 500.25MHz oscillator reference.

I had to change the CEP to reduce the effective Finesse and help to get a better stabililty => P ~ 25kW inside the FP-cavity for 30% of laser

lock oscillateur 33MHz - synth� 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics

This morning with Daniele, we changed the laser/RF locking scheme :

1) we use the laser 33MHz internal photodiode to do some beating with the 33MHz RF generator (A Rigol generator locked on the 500MHz Ring oscillator).
this beating is only for monitoring purpose, in order to manually adjust the laser frequency at the beginning of a run.

Laser cavity temperature/pressure sensitivity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

laser cavity :

when one decreases the laser motor position, the laser repetition rate increases (laser cavity length decreases).
=> +/- laser motor step => +/- laser cavity roundtrip length => -/+

Laser cavity temperature/pressure sensitivity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

Now, I placed a temperature probe stuck on the laser housing itself.

fig. 1

one can compare the temperature measured at the surface of the laser housing and the beating frequency with the 500MHz reference oscillator

Laser cavity temperature/pressure sensitivity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

the last thing we did with Daniele, is to start/stop the airflow on top of the housing (closed) to see a possible pressure effect on the laser frequency
drift.

fig 1 : in green, the temperature measured with the probe stuck on the laser housing.

Laser cavity temperature/pressure sensitivity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

today, I swapped the 500MHz RF reference oscillator for a Siglent 500MHz DDS oscillator.

see the attached plot : the beating frequency with the 500MHz laser harmonics produces the same behavior as before.
so, the oscillations should come from the laser temperature regulation.

Laser cavity temperature/pressure sensitivity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

long-term correlation, over 5-6 days, between the temperature measured in the bunker, outside of the housing (blue curve) and the temperature measured
with a probe stuck on the laser housing, inside of the FP-cavity housing (green).

it's a perfect correlation with almost the same temperature scale : 1°C outisde the housing => 1°C of laser housing

Laser cavity temperature/pressure sensitivity, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

this morning, I did a 500MHz beating frequency (Laser vs RF) drift test with the Smaract motors configured with "Sensor Mode" OFF over 50 minutes
(~ 1500 acquisitions)

compared with previous measurements, one observes a much more smooth "exponential-like" drift compared to "Sensor Mode" ON

locking, posted by Ronic Chiche at ThomX igloo about detectors and electronics

during the last days we changed the FP-cavity - RF reference locking system to force the right bucket:
in addition to the 500MHz beating which is the signal input to the PID, we added a 33MHz beating signal which is the trigger signal of the PID.
then, the lock is triggered only when this trigger signal is close to 0.

33MHz (FP-cavity vs RF) phase stability, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

this morning, with Vincent Chaumat, we made a beating (phase detection) between the laser 33MHz and the 33MHz coming from the Rigol generator locked
by the 10MHz link onto the 500MHz ring generator.

once the laser and the FP-cavity are locked on the RF reference, the 33MHz phase detection is stabilized and confirm the laser/FP-cavity lock

33MHz (FP-cavity vs RF) phase stability, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

today, I locked the laser on the FP-cavity and the FP-cavity on the RF reference with 47kW inside the FP-cavity.

equivalent jitter :

when lock is OFF : sine signal V=V0*sin(phi(t)) with V0=300mV => Vrms = 300/sqrt(2)) = 210mV rms

controller M1 & M4 (plan mirrors) with IcePap controllers, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | cabling

previously, we have connected motor M4 with an IcePap controller.
see this post : https://elog.lal.in2p3.fr/FPC/THOMX+commissioning/278

due to the backlash behavior of the FP-cavity motors, it is impossible to work in both directions on one motor when the FP-cavity is locked.

controller M1 & M4 (plan mirrors) with IcePap controllers, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | cabling

this double motors scheme works good.

if motor P4 is used by increasing value, the FP-cavityPZT signal (pink signal on scope) goes HIGHER
if motor P1 is used by increasing value, the FP-cavityPZT signal (pink signal on scope) goes LOWER

controller M1 & M4 (plan mirrors) with IcePap controllers, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | cabling

at the begining of each session, it will be mandatory to avoid any backlash for the motors :

- for the P4 motor : one can go 2k steps DOWN, then 2k steps UP to go back to -360 000 and use the
steps UP without any backlash

First stable X-rays production, posted by Ronic Chiche at ThomX igloo about detectors and electronics

this morning, we locked the laser on the FP-cavity with about 48-49kW stable in the FP-cavity (for 32% of amplifier ratio).
and then we locked the FP-cavity on the RF reference (500MHz beating lock + 33MHz beating for starting lock search).

the starting lock search voltage has been chosen between -20mV and +20mV.

Adding one photodiode in reflection, posted by Ronic Chiche at ThomX igloo about detectors and electronics

this morning, I added a DET36 photodiode in reflection (I used a thin beam splitter) to better measure the coupling over the full beam size.
this DET36 photodiode is sent to the "laser locking" oscilloscope with the other signals :
CH1 :transmission

Restarting equipements after Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software

this morning, I plugged back the 4 power cables which supply all the equipments.

all the equipments have restarted without problem, but the shutter of the laser amplifier needs a ThomX safety system grant to let the beam propagate
to the cavity...

Restarting equipements after Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software

the laser coupled into the amplifier is still measured at ~3mW at the input, on the Alphanov software, once the Amp stage are started at 0% of power
ratio.

this afternoon, Kevin restarted the 3rd safety system of ThomX to grant the opening of the beam shutter => now the shutter can be opened.

Restarting equipements after Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software

this morning, I set the Ring frequency at 500.25MHz and after switching ON the power supply of the amplifiers for the RF signal coming from the laser,
I saw the beating frequency (between ring RF and laser harmonic frerquencies at 500.25MHz) that I canceled, playing with the Smaract motor.

Now, I need to adjust the FP-cavity length to follow the laser cavity length but the IcePap DS (controlling the FP-cavity motor) freezes too

Restarting equipements after Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software

on last friday (12/01/2024), the IcePap DS issue was solved and I was able to control the FP-cavity motors properly.
I was able to quickly lock either the laser on the FP-cavity and the FP-cavity on the RF reference as before.

then, we can close these posts on restarting the equipments after the Christmas shutdown

Variable focal lens validation, posted by Ronic Chiche at ThomX igloo about lasers and optics

we plan to use Electrically Tunable Lenses EL-10-30-C NIR to build the ThomX telescope but they need to be compatible with the powerful laser beam.

for CW regime, on the datasheet (see attached file), the optical damage threshold is 10 kW/cm².
with 70W laser power and 1mm² beam surface (which is much smaller than the real beam size), we are at 7kW/cm².

Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software

this morning, I shut off all the equipements (especially the computer) except the ones powered by the UPS : laser controller, laser peltier controller,
laser motors controller.
and I disconnected the cables from the power plugs of the wall (to prevent any possible overvoltage).

Christmas shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software

this afternoon, I checked visually what happens when the AC power of the UPS is broken down => the laser controller has still its "emission"
button ON... no AC interruption.
so, I guess the UPS switched properly the output AC line from the input AC line to the internal batteries.

Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

as the CFP motors displacements induce a cavity unlock, we try to change the cavity length by changing the temperature of elment of the cavity.

yesterday, we tried to put a "heating cable" borrowed to the vacuum group to change the temperature of one bellows between the FP-cavity
and the electron ring.

Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

several days ago, we installed a heating cable around the output flange (close to the X-hutch) of the FP-cavity vessel.
we are able to heat this cable by applying a DC voltage coming from 2 DC voltage supplies in serie (2 devices with 2x 0-30V / 3A => 0-120V /
3A).

Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

today, I removed one of the DC voltage supply (as with 30V, we are already able to 30°C on the heating cable).

the remaining DC voltage supply is configured in series (2x30V = 60V max) and is at the IP address : 192.168.1.101

Ronic

Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this afternoon, I started the heating cable after the warm-up of the FP-cavity :

14h20 : start to fill 50kW in the cavity
15h : start of the heating cable @10V (2x 5V) (iteration 2300)

Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

last friday, I locked the cavity and then, switched ON the heating cable after waiting the cavity reaches a steady state in frequency drift : see the
figure.
blue : temperature of the probe on the heating cable

Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

on last tuesday, I did a long-term measurement of the frequency drift when the heating cable is powered ON at 20V (2x 10V) @ t=0mn.

the freqeuncy drift (between the laser, locked in open loop on the FP-cavity, and the RF reference oscillator) acquisition was made by the National
Instrument software.

Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

today with Fatematuj, we did a long-term frequency drift measurement between the FP-cavity loaded with 50kW and the RF reference frequency... and without
any other thermal source (no heating cable !)
we had a small lock loss at t ~ 120mn.

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

Today, after laser was modelocked, we checked the power inside the fiber coming from the Alphanov Strecher box.
it was almost zero, at the nW level.

after doing some very rough alignment, we clearly saw some power (with the powermeter) correlated with the position of mirrors, when turning

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

This morning with Viktor, we started the alignment of the CVBG and fiber.

we did a better alignment of the 2-pass CVBG.
we are able to the see a spot after PBS (after the 2 CVBG pass) which means the alignment is OK even if it can be improved.

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

In preparation for tomorrow morning, I did a test with a 45° mount to have a power pickup inside the injection box.

I used the 133MHz laser.
output power measured with the powermeter : 45mW

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

This morning with Manar, we measured the power at different points:
- direct measurement at the output of the 33MHz laser : 35 mW
inside the injection box :

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

33MHz_power_spectrum_after_double_patch_strecher_CVBG.png

I used the 33MHz spectrum measurement : https://elog.lal.in2p3.fr/FPC/THOMX+commissioning/153
fitted by P=P0*sech²((f-f0)/df)
f0 = c/1030m

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

Manar + Victor, today in the morning we aligned the CVBG of the stretcher.

The double path using the mirror mounts, reached up to 5.4 mW just before the injection into the fibers

then we rotated the quarter wave plate and the power increased by a factor of ~ 2 to 10.3 mW

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

This morning with Manar, we continued the strecher CVBG alignment and fiber injection procedure :

- we checked the power at the output of the laser and confirmed the measurement after the Isolator : ~ 36 mW
- we tried to improve the power after the strecher CVBG by rotating the quarter-wave plate but it seems we were already at the maximum : ~ 10.5

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

this morning : still 6.2 mW at the output of the fiber.

the powermeter has been removed and the fiber connected to amplifier input fiber (no EOM connected in between).

Ronic

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

Monday 7/11 morning, the power in the fiber was still 6.2 mW

Ronic
Chiche wrote:

this morning : still 6.2 mW at the output of the fiber.

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

Today, the power measured at the input of the amplifier (PD_IN on the LAL amplifier software) is 2.5mW instead of >3mW generally measured

The power coming from the NKT/Onefive Origami oscillator is still >37mW (measured directly with the powermeter at the laser output without
OD2).

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

today, the Alphanov amplifier stopped because of the too low injected power : ~2.5mW (measured by the Alphanov software)
it was still working at ~2.7mW.
normally, the injected power is ~3.1mW (equivalent to 6.2mW measured directly at the fiber output).

Strecher and fiber injection alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

This morning with Ronic, using a pickup mirror, we measured the power in different locations along the path of the stretcher box

Output power from oscillator : ~35mW

After the isolator : ~ 35 mW

New mirrors batch informations, posted by Ronic Chiche at ThomX igloo about lasers and optics

Miroirs_à_1031_nm-ThomX_-_KBox_Mars_2023.pdf

the 2 files describe the specfications for the16 mirrors ordered (4 for ThomX + spare, 4 for SBOX + spare) and the measurements made by the LMA.

FP-cavity inside power sensitivity, posted by Ronic Chiche at ThomX igloo about lasers and optics

this morning I monitored the frequency shift between the FP-cavity frequency (the laser is locked on it) and the RF reference frequency @ 500MHz,
during the warm-up time, for 50kW stored in the cavity (the recording started ~ 9h20).

one observes on fig.1 a simple exponential behavior with 500Hz frequency shift @500MHz (equivalent to ~ 10µm) for 50kW stored.

Long term lock of Laser-FP cavity-RF reference, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

today for the first time, we were able to make a long term lock of all the elements (Laser on FP cavity and FP-cavity on RF reference) during 20
minutes @50kW without any single loss of lock.

the success of this long term lock was coming from the possibility to drive the Smaract motor in piezo-scan mode and to apply a heating on one

Long term lock of Laser-FP cavity-RF reference, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

today, I did a 20 minutes "double lock" run w/o any single lock loss.

the attached file shows the recorded RMS beating voltage between 500MHz signals (laser harmonic and RF reference).
the end of the plot after iteration ~1.8k shows the lock loss to the RF reference.

Long term lock of Laser-FP cavity-RF reference, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this afternoon, we did a new long-term "double lock" run w/o any single lock loss during 1/2h.

we did 2 acquisitions :

fig 1 : phase measurement between the 33MHz signal coming from the laser and the 500MHz RF.

Smaract motors parameters and controller, posted by Ronic Chiche at ThomX igloo about mechanics | detectors and electronics

current Smaract motors parameters :
- Closed loop Max frequency : 5000
- Signal Amplitude threshold : 2047

Temperature control of the Laser length with the inside Peltier, posted by Ronic Chiche at ThomX igloo about lasers and optics

bunker temperature @ 22.5°C

today, Sebastien Pitrel improved its python software to manually control the laser peltier.

Laser / FP-cavity "day by day" locking, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

today, we locked the FP cavity at ~50kW with 30% laser amplifier ratio (16W) during almost all the day (from 10am to 4pm)
CEP optimized for MCS-1/Ch2 = -244µm at the end of the day.

once one finds the proper CEP value to reach to correct loops gain, the cavity lock and power are very stable:

Laser / FP-cavity "day by day" locking, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

as the temperature is back to a normal value ~ 20.8°C, the injected power to the amplifier (PD_IN in the Alphanov software) is back to 3.15mW without
doing any alignment.

this morning the lock was around 48.5kW with 30% laser amplifier ratio (16W) after CEP/alignment tuning.

Laser / FP-cavity "day by day" locking, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

temperature since we moved to temperature probe (jump at the beginning of the plot) below the ring on a metallic base.

Ronic
Chiche wrote:

as the temperature is back to a normal value ~ 20.8°C, the injected

Laser / FP-cavity "day by day" locking, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

temperature @ 22.3°C

today, all the PC applications were closed except the web browser.
I had to restart all of them, then try to relock.

Laser / FP-cavity "day by day" locking, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

temperature @ 21.9°C

48.5kW inside CFP for 30% amplifier ratio

Frep Laser motor = 123.4µm

bunker temperature curve, posted by Ronic Chiche at ThomX igloo about detectors and electronics

M4 motor using icepap controller and jive/Atkpanel IHM, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

Kevin moved the M4 mirror controller from the ISP controller to some ICEPAP controller.

the IHM to access this ICEPAP controller is accessible by launching 'jive' from any account ('operateur.thomx' for example).

once in the jive window, one has to select the 'device' tab, then select the OC=>OP=>OCH.02-MOT.03 device.

M4 motor using icepap controller and jive/Atkpanel IHM, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

one problem is the FP-cavity/laser lock loss when one moves a FP-cavity motor.

with acceleration = 0.01 units/s² and velocity = 50mm/s (here, the 'mm' unit seems strange as it is very fast), it's enough
to make a move fast enough for small displacements (10 steps for example to center PZT position) and it seems that the cavity stays locked (only the FP-cavity/laser

Ring frequency / Laser "day by day" locking, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

today, the equivalent Smaract position corresponding to the 500.25MHz ring frequency is +156µm on MCS-1/ch0 (closed loop mode)

Ring frequency / Laser "day by day" locking, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

temperature stable around 20.8°C

today, the equivalent Smaract position corresponding to the 500.25MHz ring frequency is +158.4µm on MCS-1/ch0 (closed loop mode)

it is very difficult to maintain both loops in the same time as soon as it is needed to move one motor (CFP or Laser) because of the one element

Ring frequency / Laser "day by day" locking, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

temperature stable around 21.7°C

today, the equivalent Smaract position corresponding to the 500.25MHz ring frequency is +147µm on MCS-1/ch0 (closed loop mode)

Ronic

some changes in the feedback scheme, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

from several weeks, the maximum power stored in the FP-cavity was ~ 5kW.

today with Daniele, we finished to investigate the problem, and now the power inside the FP-cavity is back
to ~50kW for 30% of laser amplifier ratio (~16W).

!!! strange amplifier beam pointing fluctuations !!!, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

this morning, I locked the cavity to ~25kW without any problem.

but this afternoon, the reflected power exhibited low frequency (~1Hz) fluctuations of about 10% without any lock.
the reflected PhD is a DET10 which has a small surface.

!!! strange amplifier beam pointing fluctuations !!!, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics

we confirmed the effect of the bunker temperature on the laser amplifier "beam pointing" fluctuations.
once the temperature is getting back to stable values, it doesn't happend again.

we bought a temperature data logguer to monitor them in the future: https://www.picotech.com/data-logger/tc-08/thermocouple-data-logger

Tests of pointing stability of the laser CFP, posted by Daniele Nutarelli at ThomX igloo about lasers and optics

Last monday with Victor we have cheked the stability of de pointing of the laser FP.

The climatisation was operating since 3 days in satble way. The laser pointing was very stable before to inejct in to the cavity (picture 1)
and also for the reflexion from the cavity (picture 2).

Laser FP operation, posted by Daniele Nutarelli at Optical room about lasers and optics

This morning FP Laser was operating well locked at 30 KWatts in stable vay.

There are some fluctuations due tu pointing instabilities probably dues to temperature fluctuations in de bunker.

In the attacced picture are reported the lock parameters and signals.

Fast feedback loop between laser and FP cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

today, we tried to lock the FP cavity with the Smaract motors ON (with option -LV).
we know the Smaract controllers produce some noise and the lock is very bad or impossible when the controller in ON (whatever the displacement mode
is : closed or open loop, or piezo scan).

Fast feedback loop between laser and FP cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

today, after the several unsuccessful attempt yesterday to get an improvement in the lock,
we decided to "rebuild" the error signal electronics block by block and step by step :
the scheme is basically :

Fast feedback loop between laser and FP cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

this afternoon, we tried to better understand how to drive properly the EOM to kill high frequency noise.

we locked to laser on the FP-cavity as usual.

then we injected a 0-10V square signal on the laser EOM @ 1KHz (with fast rise and fall times ~ 10ns)

Fast feedback loop between laser and FP cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

I copy the post about Fast Feedback loop : https://elog.lal.in2p3.fr/FPC/THOMX+commissioning/265

This morning,

- I installed the fast feedback loop.

!!! strange FP cavity behavior => impossible to lock !!!, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

suddenly, BEFORE switching the HV amplifier ON and BEFORE connecting it to the EOM (in order to explore the HV effect on the EOM for the fast feedback
loop),
we lost the lock between the laser and the FP-cavity: in attchement a plot a the lock with the "best" PID parameters.

!!! strange FP cavity behavior => impossible to lock !!!, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this morning, we tried:

- to move a bit the arm of the L-shape off the beam axis (in case of it could have touch something and induce vibrations) => no effect

- to change the CEP to get an equivalent lower Finesse => weak improvement

!!! strange FP cavity behavior => impossible to lock !!!, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

it could be also an optical unstability, as when the intra-cavity power increases, the radius of curvatures of the mirrors increases too due to thermal
effect, and then one could go in the instability region.

but if it was the case, by reducing the power in the FP-cavity, we would also reduce the thermal effect and then, we would come back in the stability

!!! strange FP cavity behavior => impossible to lock !!!, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

This morning,

- I installed the fast feedback loop.
now, the error signal goes to the Laselock AND

!!! strange FP cavity behavior => impossible to lock !!!, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this afternoon, in adjusting the CEP and improving the parameters of the lock, I was able to get ~ 47kW stable inside the cavity, always for 30% of laser
amplification ratio.

it confirms that the Finesse, and then the gain of FP-cavity, has suddenly increased thanks to some "mirrors surface cleaning"

drift calculation for the SMA100A, posted by Ronic Chiche at ThomX igloo about lasers and optics

the goal is to estimate what could be the frequency drift at 500MHz for the SMA100A: see phase noise datasheet in attachement

Sphi(f) = FFT ( Rphi(T) ) = FFT ( < Phi(t) Phi(t+T) > )

at low frequency, Sphi(f) ~ A / (f^n) = A*(2pi)^n / (i2pi*f)^n => Rphi(T) = A*(2pi)^n*T^(n-1) / (n-1)!

work with HV voltage on the Laselock, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

presently, the voltage on the laser PZT is 0-10V, but during the several runs we did, this voltage is too low to compensate low frequency fluctuations:
we need to change often the motors position implying a cavity lock loss.

we have to check if running the laser PZT with the HV output of the Laselock is possible without too much additionnal noise.

work with HV voltage on the Laselock, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

Yesterday, I checked the 2 output HV channels of the LaseLock : they work properly but the noise is bigger than the low voltage outputs
~ 1mV rms on 0-10V outputs
~ 8 mv rms on 0-100V output

work with HV voltage on the Laselock, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics

This afternoon, I connected the HV output of the Laselock (instead of the standard 0-10V output) to the FP-cavity PZT to increase the locking range.
I didn't see any degradation of the FP-cavity/synthesizer lock.

Ronic

Removing high order modes, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

this morning we locked the laser and the FP-cavity with ~ 40kW => some HOM appeared "randomly" depending on the power.

we tried to play manually on the L-shape arm :
- first, we moved horizontally to put the L-shape in the beam axis

Removing high order modes, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

here is the picture of the L-shape arm and the inside of the vessel.

this image corresponds to the "zero" position on each positionner.

Ronic

Removing high order modes, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics

yesterday with Daniele, we tried again to move the arm horizontally and vertically from the "zero position" to have a better understanding
of the beahvior,
but it is roughly the same :

33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics

120705_Displacement_of_cylindrical_piezo_ceramics.xls

the last tries to lock the 33MHz + amplifier to the 30k Finesse FP-cavity were unsuccessful.

during a laser Frep scan using the Laselock, one observes that the main cavity resonance is not able to stay inside the PZT scan range from one
scan to another (500ms-1s period)

33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics

finding the right modulation/demodulation PDH phase is very difficult on the main resonance because the we get non stationnary signals with a lot of
oscillations.
changing the phase, in this condition, does not really change the error signal.

33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics

today with Daniele, we locked easily (but with a noisy lock) on the secundary resonance and we tried to lock on the main resonance (with very low coupling
~10% which mean a CEP ~Pi)
the lock was possible but was very noisy.

33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics

After removing the 2 generators from the optical table, the lock is much more stable and now, it is possible to lock on the main resonance with a poor
CEP but with quite good stability.
the coupling is still very low ~ 5% for that CEP but if one improves it (CEP ->0), using the laser double-wedge motor, one clearly sees an improvement

33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics

this morning, I tested the laser+amplifier @ 30% lock on the FP cavity with and without Smaract motors.

I recorded the PDH error signal during a lock:
- blue : with Smaract motors controller powered ON but motors are stopped

33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics

I checked with the Matlab code below the CEP detuning effect (2nm sech² spectrum... not exactly the same as in ThomX)
@ CEP = 0 => coupling = 100% and Gcav = 10.5k
if all the coupling loss comes from the CEP detuning effect :

33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics

we checked yesterday morning the real input power @ 30% for the amp => it is 16W in agreement with the previously measured values

Ronic
Chiche wrote:

I checked with the Matlab code below the CEP detuning effect (2nm

33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics

Today, we locked the cavity with input power @ 30% for the amp => we got 40kW with only 30% of coupling (and a bad lock => we could have more power
inside cavity).

P@30% = 16W

33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics

redoing the PDH error signal scheme with discrete components is more flexible and it is easier to check the signal/noise ratio.
now, we are able to get a quite clean lock only with the PZT correction (w/o fast feedback correction using the EOM) even with both motors controllers
ON (cavity and laser).

Onefive laser modelock and Smaract CEP controller, posted by Ronic Chiche at ThomX igloo about lasers and optics

today, during an attempt in improving the CEP with the Smaract controller CH2, we lost the laser modelock.

at this point, we decided to reference the Smaract CH2 for CEP :
now, 0 mm is roughly the middle of the motor range.

Smaract controller remplacement, posted by Ronic Chiche at ThomX igloo about lasers and optics

previously, we were using a spare Smaract MCS controller to drive the Onefive linear stages (without -LV -low vibration- option and
using Ethernet),
during the repair of the initial MCS controller with -LV option.

FP-cavity FSR shift, posted by Ronic Chiche at ThomX igloo about lasers and optics

today, to match the ring frequency at 500.25MHz (15th laser harmonic), we did a frequency shift on the laser using the Smaract motors (not too fast,
~2µm/s, to prevent laser modelock loss)
and we "followed" this shift on the FP-cavity using the FP-cavity motors.

Equipments shutdown, posted by Ronic Chiche at ThomX igloo about lasers and optics

on the August 30rd and 31th, a global power shutdown was forseen for ThomX.

to prevent damage on equipments, I switched off all of them (and disconnected power cables from the wall plugs).

yesterday, after the week-end, all the equipments have been restarted and the cavity as been locked properly.

ThomX ring injection kicker noise => USB communication issue with Alphanov amplifier, posted by Ronic Chiche at ThomX igloo about detectors and electronics

several times already, when the electrons ring injection kicker is running @10Hz, we observed peaks at the same frequency on reflected and transmitted
photodiodes,
at the exact moment when the kicker is activated. we have in addition, USB communication issues with the Alphanov amplifier... the connection is

Incoming laser beam power issue, posted by Ronic Chiche at ThomX igloo about lasers and optics

today, we observed on the photodiode used in reflexion of the cavity, that its voltage level stops increasing after 50% of power for the laser amplifier
when the cavity is not locked (the FP-cavity is just a reflective mirror).
the photodiode itself is not saturated (low power sent after a wedge and an absorbing filter) and the reading is done on 50 ohms.

First X rays and FP-cavity mode and electron beam waists size @ IP, posted by Ronic Chiche at ThomX igloo about lasers and optics

on friday 23/06 afternoon, after scanning the hexapod z-axis, we observed a cut of the power stored in the FP-cavity (with constant input power/coupling)
at both ends of the scan, due to the losses of the beam-pipe aperture.
we placed the hexapod exactly in the middle of this range ~ z=-1.68 mm (which is not the middle of the maximum range of the hexapod), we opened

PW laser Injection into cavity , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

Yesterday,

we installed the second high power reflecting mirrors at the output of the amplifier.
We aligned and installed a telescope
that has adjustable distance between the 2 lenses of -100 mm, and + 200 mm, with approximate diameter at the injection window of ~ 4.5 mm.
Amplifier

PW laser Injection into cavity , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

20230418_size_of_beam_before_injection_window_at_10percetage_ampli.jpg

20230418_coupling_at_the_start_only_alignment_improved1.jpg

20230418_zoom_on_Oscilliscope_signal_fundamental_mode.jpg

20230418_coupling_after_improving_it_with_regulator_on_attempting_to_lock.jpg

On Monday with Daniele,

we did full characterization of amplifier beam @ 10% amplification, adjusted the telescope accordingly
and injected into the cavity aligned and improved on the fundamental mode.

On Tuesday with Daniele and Kevin

I
added a low pass filter between 1 - 1.9 MHz on the reflected signal, to reject the oscillator signal (33.33 MHz)
removed the external resistors

PW laser Injection into cavity , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

Added Note: the coupling we get is at low power, only preamplifier is on (~ 300 mW)

was done at the end due to excitation of higher order modes.

Wanted to improve the fundamental first, then increase the power.

PW laser Injection into cavity , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

Today with Ronic and Daniele we attempted to lock the cavity, but the alphanov amplifier did not turn on because of an error in MMD3 (related to the
third stage)

the new error is having the MMD3 error show on the alarm window of the LAL software, and having the Alarms on the line 3 of the alphanov software

Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software

This morning, while trying Guillaume solution of disconnecting the 24 V necessary to the second and third stage and raise the threshold of Temp preamp
1 (to only operate the ampli with first stage only)

Ronic disconnected the 24 volt connection, turned on amplifier LAL software but no MMD3 error or a big temp on Temp preamp 1 , software worked

Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software 13x

Yesterday, with Ronic we locked ThomX cavity on the second resonance

Laser : 33.36 MHz , Amplifier : 0 % (worked with no errors all day)

adding image for the lock on the second resonance (locked), 00 Mode image, fit, Beam measurements

Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software

Today, I installed a power meter at the transmission point of the 1st spherical mirror , transmission 3 ppm (direct from cavity window beam profiler,
no filter)

We locked the cavity at 2 different resonances of the fundamental mode, the lock in both cases was stable for a round 1 minute.

Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software

Today with Ronic,

starting with major events that happened (Water circulation + ThomX valves )

Early in the morning a company worked on the water network, it seemed it was not restarted properly so there was no water circulation

Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software

tek00000_cavity_lock_with_noise_from_odcillator_controller.png

In the morning, we locked on the first resonance. With an increase on the amplifier power @ 20-25% and 30%, which reduced the noise

we manage to get a coupling when improving the CEP up to 55 - 60 % coupling : put there is still a drift on the CEP

The controller for the oscillator frep and CEP produces a lot of noise, even if it is disconnected. we need to switch it off to remove its effect

Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software

The computer is possible to connect from the control room,

we are able to run remotely the amplifier, cavity motors, oscillator motors, lase lock (note: there is an issue with the keyboard, we are not
able to use it with remote access!!!!!!!!)

Cavity Alighnment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics 9x

Last week, with Ronic and Victor we aligned the cavity using CW laser (Koheras)

we have also installed 4 mirrors in the cavity with the best theoretical qualities (serial number and images included)

The
Plan ULE mirror P4 thickness was not compatible with the piezoelectric mount. We had to install a metal spacer behind the mirror

Cavity Alighnment , posted by Manar Amer at ThomX igloo about lasers and optics | vacuum | detectors and electronics

Today, we prepared lenses for a telescope for the CW laser injection into the cavity, yet to be installed

Image of the transmission at P4 attached, an estimation of the beam size of the mode see is ~ 5.5 mm

The vacuum in the 2 optical cavities is decreasing but slowly. today it is 2.6 - 2.4 * 10^-7 mbar

CW FP Cavit lock , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

Yesterday morning we locked the cavity on a strange mode in the cavity (we call it mode, but not sure what it is ??)

we also managed to lock on a higher order mode 02

we get an estimated 30% coupling (expected value), and note that we have not installed a telescope yet.

CW FP Cavit lock , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

This morning with Daniele and Viktor,

- we confirmed the "potato" mode was well centered on the injected beam and was not due to some misalignment of the injected beam compared
to the cavity axis.

FP Finesse measurement using CW, posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

20230411_Beam_Profile_position_differance_when_changing_FSR.JPG

This morning, with Ronic and Daniele, we locked the cavity again (The lock was relatively easy and stable during the reading of the finesse)

We took 2 reading of finesse

1st : @ 33.2808 MHz (what the cavity length was at) : Finesse =

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics

today with Manar, we brought everything to make the profile measurement.

the chiller was in error because of the water level : we filled it in.
! warning ! there is no alarm signal, only a message on the screen.

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics

yesterday morning with Manar,

1) we fixed the threshold level of the laser input signal which makes the measurement of the repetition rate.
(if the rep rate is not measured properly, the amplifier safety interlock stops immediately the amplification).

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics

this morning with Manar,

- we checked first the chiller problem.
the fluctations of +/-2° around 25°C are still there.

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

Today with Ronic

For the Temperature fluctuation :

we checked the valves of the tubes bumping water into the chiller from ThomX main water supply, they were

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics

this morning with Manar,

- we fixed the chiller problem (+/-2°C fluctuation around the set temperature value = 25°C).
we opened and closed several times the water valve of the primary circuit to remove air bubles => no effect on the temperature variations.

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

Ronic on Friday operated the Amplifier from the Alphanov software, switched it off then turned on the LAL software,

and it worked for 40 min without issues or error appearing,

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

the laser amplifier worked for some days but it ended to a "watchdog" alarm which switches off the amplifier... investigation is ongoing

Ronic
Chiche wrote:

Ronic on Friday operated the Amplifier from the Alphanov software,

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

we have had this new issue (watchdog alarm switching off the amplifier) for several days.

Alphanov mentionned it could come from the input oscillator stability (modelock loss for example).

Today,

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

With Daniele after, we took a readings of the beam with a lens of 750 mm.

From the observed data, we can state that the beam is not completely Gaussian M2 > 1, due to the variation of the ellipticity of the beam
along the focused path

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

This morning,

- with the "Alphanov" software => Central panel => "system" button => Watchdog "Period Max" was at 100ns
and has been set to 200ns.

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

This morning with Daniele, we did a second measurement of the beam profile using a different lens of focal 400 mm.

at a power amplification of 20%

the amplifier stayed on for around one hour and a half with no errors.

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

On Monday 20th of February, Daniele and Viktor took some beam profile measurement data @ 50% of power amplification.

data and analysis can be found in the attached file.

Ronic

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

Yesterday, Guillaume Machinet and Vincent Clet from Alphanov came to fixe some issues with the laser amplifier:

- 1) they fixed the "rep. rate" measurement issue.
previously, the voltage range in which it was possible to detect the correct rep rate (33MHz) was very narrow ~ 50mV.

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

WhatsApp_Image_2023-02-27_at_6.07.00_PM.jpeg

This morning with Victor we took a reading of the beam profile using a 400 mm lens at 70 % and 100 % amplification.

Will process the data and add after

Note : after an hour and half of amplifier on at 70% we increased the power to 100%, and after ~ 10 minutes the amplifier turned off and showed

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

this morning with Manar,
we checked the Alphanov amplifier issue : "The laser has been stopped because its power is too far from the nominal power".

the photodiode voltage measuring the output power has drifted again and then, the estimated output power was wrong, triggering an alarm issue.

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

We took reading of the beam profile of the amplifier without a lens @ 30 cm from the 2nd wedge for amplification percentages

20-30-40-50-60-70-80-90-100 % another additional 3 readings will be taken at different locations for all amplification percentages.

Alphanov amplifier beam profile measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | software

due to several "case temperature" issues, I change the "Max case temperature" in the "general config" of the "Alphanov
Software" from 50°C to 55°C.
=> validated by Alphanov.

Power shut down on Saturday the 18th, posted by Ronic Chiche at ThomX igloo about utilities

All the equipments have been switched off on Friday 17th due to a power shut down on Saturday 18th :
CW and Onefive oscillators, computers, laser amplifier, cavity mirror motors, chiller, etc...

Power shut down on Saturday the 18th, posted by Ronic Chiche at ThomX igloo about utilities

Today, I restarted all the equipements :

Chiller
: ok, temperature converged quickly to the set temperature : 25°C

33MHz laser SN2439 back to Orsay, posted by Ronic Chiche at Optical room about lasers and optics

On the 8th of July, the SN2439 33MHz laser was returned from NKT to our lab, being repaired.

it stayed all the weekend to warm up in the optical room and has been turned on on Monday.

the mode-locking was not working (28mW output power and a CW line for the optical spectrum), thus I "kicked" the laser with 100µm

33MHz laser SN2439 back to Orsay, posted by Ronic Chiche at Optical room about lasers and optics

This morning, with Aurélien and Daniele, we did the swap between the 33MHz and 133MHz oscillators.

now, the 33MHz oscillator is on ThomX inside the casemate.
it has been restarted and some laser is going out.

33MHz laser SN2439 back to Orsay, posted by Ronic Chiche at Optical room about lasers and optics

Stick-Slip_Positioners_Mechanical_and_Electrical_Interface_Data_Sheet.pdf

Yesterday with Aurélien, we try to make the laser modelock using the Smaract translation stages embedded inside the laser head.

unfortunately, we got some errors when we try to do the "calibration" and "reference" of both Smaract stages !
we contacted by email M. Nicoul to help us on this topic

33MHz laser SN2439 back to Orsay, posted by Ronic Chiche at Optical room about lasers and optics

Today, we used an "ELI-NP" Smaract controller made with these 2 references :
MCS-3CC-ETH-TAB (SN 2271) => main controller
MCS-3S-EP-SDS15-TAB (SN 2472) => sensor module

33MHz laser SN2439 back to Orsay, posted by Ronic Chiche at Optical room about lasers and optics

Yesterday, we put back the 33MHz oscillator into the casemate with the new Smaract controller.
after switching ON the laser controller, we saw some power at the output but we have to check if the laser is modelock or not.

Ronic

33MHz laser SN2439 back to Orsay, posted by Ronic Chiche at Optical room about lasers and optics

Today, we succeded to make the laser modelock.
the ouptut power is above 35mW (the powermeter was saturated)
here is a screenshot of the signal on the scope.

33MHz laser SN2439 back to Orsay, posted by Ronic Chiche at Optical room about lasers and optics

MCS_Network_Interface_Configuration_Guide-1.pdf

As the general local network for the FP-cavity devices is 192.168.xxx.xxx, I changed the IP adress of the smaract laser motors (Frep and CEP) controller.

For that, I used the embedded web server as described in the manual in attached file.

the new adresses are :

New Mirrors from LMA _ Images, posted by Manar Amer at Optical room about lasers and optics

20230317_Images_of_New_Mirrors-compressed.pptx

WhatsApp_Image_2023-03-17_at_6.39.44_PM.jpg

Today we tested a mirror from one patch

image is for the front face of the mirror

PowerPoint has more details about the images

Amplifier Beam Profile over time , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

This morning, with Ronic, we opened the compressor box to observe if there is any misalignment of the mounts or the CVBG's

a comparison slide between the Beam Profile over time and measurements we have taken, is included.

we noticed
today that the images need a rotation, and I took the assumption we did not rotate last year and did the rotation of the previous images.

Comparing

Amplifier Beam Profile over time , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics 10x

This morning we took data of the beam profile at 4 different points to see the evolution of

the beam shape
divergence

over distance for all amplification percentages

Data plotted for the distance vs radius for all and divergence in rad is extracted and plotted as a variation of amplification power.

Amplifier Beam Profile over time , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

Information about today's work is added to logBook !!

Manar
Amer wrote:

This morning we took data of the beam profile at 4 different points

CW laser installation and cleaning, posted by Ronic Chiche at ThomX igloo about lasers and optics

This morning with Manar, in order to prepare the installation of the news FP cavity mirrors,

- we installed the Koheras below the optical table
- we put a fiber prolongator at the end of the Koheras fiber and we put a mounted collimator at the end of the fiber.

CW laser installation and cleaning, posted by Ronic Chiche at ThomX igloo about lasers and optics

This morning with Ronic , in preparation for the mirror installation, we removed additional mechanics and cables from the table.

We organized and cleaned the permanently installed cables on the table away from the area of the cavity opening.

We opened the two top vents and left the shutters open to circulate clean air , (note the shutters surrounding the laser and amplifier are half

Alphanov amplifier beam profile Data , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics 8x

Adding the schematic of the measurements.,

the 4° Beam Deviation, AR Coating ( B coating)

The 3 data points taken of the beam profile are fitted in Gaussian Beam with taking the beam waist at the output of the compressor box.

Alphanov amplifier beam profile Data , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

This Morning with Victor the amplifier was turned on @ 20% amplification (output ~ 9 W ) for approximately 3 hours and no error appeared.

I took data of the beam profile at different points without a lens after the 2 wedges

@ 0% (only pump beam), output ~ 300 mW (taken from previous data) , output after 2 wedges 2.2 uW

Amplifier output power , posted by Lo�c Amoudry at Optical room about lasers and optics

The ouput power of the ThomX amplifier has been measured as a function of the 3rd stage pumps current (0A is 1st and 2nd stage turned on).

We measured the total power, the total power without the "donuts" pump signal dumped by an iris and the transmission of a dichroic
mirror (for ref see image).

Amplifier output power , posted by Lo�c Amoudry at Optical room about lasers and optics

Loïc
Amoudry wrote:

The ouput power of the ThomX amplifier has been measured as a function

Amplifier output power , posted by Lo�c Amoudry at Optical room about lasers and optics

We checked the Dichroic mirror we have : it is a DMSP1000 shortpass dichroic mirror as specified in this post.

The Arrow engraved on the edge of the mirror points on the AR surface !
not on the HR surface...

mirrors removing, posted by Ronic Chiche at ThomX igloo about lasers and optics

This morning with Viktor, we opened the 2 vessels and removed the 4 FP-cavity mirrors.

all the mirrors have been put in plastic boxes with labels to indicate which mirror it is,

and with all the HR coatings face down.

Vessels vacuum at ambiant pressure, posted by Ronic Chiche at ThomX igloo about vacuum

Last Friday and this morning, with Bruno, we close the ring/cavity valves and put some dry air in the two vessels through a filter to avoid turbulences.

Now, the two vessels are at ambient pressure and ready for opening (to remove the mirrors).

One can let the ambient pressure in the vessels as long as we want, the ring/cavity valves have been chosen to be compatible with the high vacuum

Alphanov amplifier compressor's CVBG thermal images, posted by Ronic Chiche at ThomX igloo about lasers and optics

last Friday with Manar, we took some thermal images of the Alpnavov compressor box.

I post a small document to summarize some points :

- the 2 mirrors used to make the CVBG injection are polarized thin-film mirrors... thus sensitive to the beam polarization.

Alphanov amplifier compressor's CVBG thermal images, posted by Ronic Chiche at ThomX igloo about lasers and optics

Alphanov amplifier Beam Profile, posted by Manar Amer at ThomX igloo about lasers and optics 8x

Today: Manar, Ronic and Aurlien started the study of the beam profile of the alphanov amplifier at high power.

The setup shown in the image shows how the power is reduced by using Anti-reflective mirrors,

pick up 1 : Anti-reflective coating on both sides , pick up 2 : Anti-reflective coating on one side and High

Alphanov amplifier Beam Profile, posted by Manar Amer at ThomX igloo about lasers and optics

Manar
Amer wrote:

Today: Manar, Ronic and Aurlien started the study of the beam profile

Alphanov amplifier Beam Profile, posted by Manar Amer at ThomX igloo about lasers and optics 6x

Adding the fitted beam in 1D in Horizontal and vertical axis.

for 10% to 60%

Manar

Alphanov amplifier Beam Profile, posted by Manar Amer at ThomX igloo about lasers and optics

Today a second reading of the beam profile was done , with Victor ,Ronic, Aurlien and Manar

an additional set-up was made using two 4 deg wedges instead of High reflecting (HR) and Anti-reflecting (AR) mirrors.

Two reading were taken:

Alphanov amplifier Beam Profile, posted by Manar Amer at ThomX igloo about lasers and optics 9x

Readings of the beam shape and horizontal (upper plot) and vertical (lower plot) axis fit at the direct output of the amplifier.

The beam shape relatively shaped like an egg.

Manar

Alphanov amplifier Beam Profile, posted by Manar Amer at ThomX igloo about lasers and optics

20220401_Amplifier_AfterCompressor_50perc_133MHz_BeamFit.png

20220401_Amplifier_AfterCompressor_60perc_133MHz_BeamFit.png

Readings of the beam shape and fit at the output of the compressor

differance from previous reading is that here we used wedges instead of HR mirrors.

Similar to previous readings, the beam shape deforms and the Gaussian fit is bad after 50% amplification

Alphanov amplifier Beam Profile, posted by Manar Amer at ThomX igloo about lasers and optics 6x

Adding the readings 20% , 30% , 40% for output of amplifier after the compressor

Manar

Alphanov amplifier Beam Profile, posted by Manar Amer at ThomX igloo about lasers and optics 12x

This Morning, another reading was taken for the output of the amplifier after the compressor using 2 wedge mirrors.

In addition, a start of the calibration of a PulseCheck "Autocorrelator" to measure the pulse duration.

note, the pulsed laser used is OneFive 133.33 MHz

Alphanov amplifier Beam Profile, posted by Manar Amer at ThomX igloo about lasers and optics 20x

Victor, Ronic, Manar

Today was dedicated to the study of the CVBG, and it's effect on the beam profile

we opened the box containing the 2 CVBGs : The 2CVBG are glued from the bottom on a copper surface .

Alphanov amplifier Beam Profile, posted by Manar Amer at ThomX igloo about lasers and optics 8x

For better comparison ,

the measurements done previously with 2 CVBGs was done at ~ 30 cm and the one done on Friday was for 1 CVBG is at 1 m

so we did additional measurement for 2 CVBGs at 1 m, for 20 , 50 and 70 % amplification

Alphanov amplifier Beam Pulse Duration, posted by Manar Amer at ThomX igloo about lasers and optics

The pulse duration from the amplifier compressor output will be measured using PulseCheck autocorelator

a first alignment of the device was done, continuation in the afternoon.

YouTube link attached of the general operation of pulse check < 5 min : https://www.youtube.com/watch?v=J1pNHYySSYg

Alphanov amplifier Beam Pulse Duration, posted by Manar Amer at ThomX igloo about lasers and optics

20220408_AMplifier_133MHz_Pulse_duration_better_alignment.jpg

Measurement of the pulse was done at the end of the afternoon, Pulse Duration FWHM = 12.9 ps

After a long process of adjusting the alignment and angle of the crystal inside the device

The power input on the PulseCheck device should be above the sensitivity, in our case we had 1 mW input.

Alphanov amplifier Beam Pulse Duration, posted by Manar Amer at ThomX igloo about lasers and optics

Pulse Duration FWHM = 12.9 ps

Manar
Amer wrote:

Measurement of the pulse was done at the end of the afternoon, Pulse

First hands on the Alphanov amplifier & software, posted by Ronic Chiche at ThomX igloo about lasers and optics

Aurélien, Manar, and I spent more than 2h trying to start the software communicating with the Alphanov amplifier controller.

each time, we had a problem with the software, asking to switch OFF and ON the controller before being able to switch the amplifier diodes ON.
we switched OFF and ON many times without any success.

First hands on the Alphanov amplifier & software, posted by Ronic Chiche at ThomX igloo about lasers and optics

Additional information related to the injected power into the amplifier fibers.

power = 4.45 mW (as shown from the software)

the minimum to inject into amplifier is 2 mW

First hands on the Alphanov amplifier & software, posted by Ronic Chiche at ThomX igloo about lasers and optics

Software Works well and is operational.

Just closing the log series!!!

Ronic

Alphanov amplifier power measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics

This morning, with Manar and Aurélien, we measure the power directly at the output of the Alphanov amplifier with the 2 compressors CVBG
(seeding laser at Frep = 133MHz)
(we had to remove the base plate where the deflector mirrors were mounted to put the large powermeter).

Alphanov amplifier power measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics

answers from Guillaume:

- the chiller temperature has to be set to 25°C
- the power measured with the software can change a little from what Alphanov measured with their laser.

Current Installed Setup, posted by Manar Amer at ThomX igloo about mechanics | lasers and optics | detectors and electronics

Attached is the current setup in ThomX

Cavity beam Image , posted by Manar Amer at ThomX igloo about lasers and optics

Updated beam image after change on the mode axis.

Taken after P4.

FP cavity mode axis change and Finesse measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics

this morning with Manar, we did a cavity mode axis change.

we checked the cavity mode centroid position on the beam profiler (placed behind P4) and changed it by roughly 1mm on the X-axis and by 500µm
on the Y-axis.

Cavity Lock and Finess measurment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics 6x

This morning, me and Ronic managed to obtain the FSR and image of the finesse which is to be analyzed.

Adding:

Beam Image at P4 propagation, no lens is added.
Image of the Finesse on Oscilloscope

more information to

Cavity Lock and Finess measurment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

to measure the Finesse, instead of having 2x EOM for the PDH and for the modulation sweep, I simply used 2x generators coupled with DC-blocks
to a T connector (SMA) screwed directly on the EOM input.

Cavity Lock and Finess measurment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

After changing the way of injecting modulation for PDH and modulation for FSR scanning (we split the modulations to 2 different EOMs), the locking
is very stable and we can measure the Finesse.

Cavity Lock and Finess measurment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

one thing which could reduce the Finesse is the L-shape metal piece if it is slightly inserted in the FP-cavity mode path.
understanding where this L-shape effectively is is not easy... some pictures are attached.

Manar

FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics

Note the direction of injection is M1 - M2 - M3 - M4

P1 - S2 - S3 - P4

FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics

The alignment is on hold until next week 17th - 18th Jan

an Alignment attempt will be done when the ring part close to the FP cavity is opened.

Manar

FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics

***** Continuation of the alignment ---- FP Cavity Open --- ****

The cavity was put under outer pressure and was opened for the alignment

The alignment was done using CW koheras infrared laser and the inside mirrors irises

FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics

Yesterday, we did the alignment again using Iris and beam profilers to obtain a more precise result.
at the end of the alignment procedure, we successfully obtained the beating modes.

the geometrical alignment seems good (weak odd modes) but we could need to put a telescope on the Koheras line as the beam size seems quite different

FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

Installed and inputs:

CW laser ; power = 101 mW
PDH ;

at output

Low pass filter 50 ohm  DC-1.9 MHz

at
input

freq = 8.4 MHz , Ampl = 1.2 V  , phase = 160 /
voltage =   ~ 6 V

EOM

FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

This afternoon, I did some alignment of the injection mirrors with a fast scan on the LaseLock to get a regular transmission photodiode signal.
the coupling increased to 10-15%

I got a first lock of the cavity only with the PZT.

FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

This morning with Manar, we installed the AOM+RF amplifier and the associated fast feedback loop.
Now the locking with the Koheras is good with a coupling of 20%.
Tomorrow is dedicated to the measurement of the Finesse.... we will have to add the 2nd EOM.

FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

Adding Oscilloscope images

delocked + locked intervals showing the 20% coupling
lock when the housing panels are closed + airflow on .
lock
when the housing panels are closed + air flow at lowest setting

an additional factor to the PZT voltage sensitivity

FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

Ending alignment series !!

Manar
Amer wrote:

Adding Oscilloscope images

FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

As it can be seen on the first plot, even with a good locking (good reduction of "high" frequencies noise: we had better locking than on the
picture) we still have very low frequency (~ 1Hz) fluctuations

these fluctuations prevent having a good measurement of the Finesse and they need to be understood.

FP cavity alignment , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics

The fluctuation problem has been solved.
It was simply the new scheme to inject 2 RF frequencies in a single EOM.
It maybe produces some standing waves in the EOM RF input and creates some phase noise.

Documentation about mechanics on Atrium, posted by Ronic Chiche at ThomX igloo about mechanics

https://atrium.in2p3.fr/0dded51a-1cb0-43e6-ae0d-626cd5db7078

a lot of schematics regarding the FP cavity are stored by the mechanic group on the Atrium repository.

Alignment procedure, posted by Ronic Chiche at Optical room about mechanics | lasers and optics

we did again the complete alignment procedure starting with iris and optimizing injection motors Ma and Mb, then installing mirror S2, S3, P4 and P1,
optimizing thetaX and thetaY axis for each motor.

everything was fine until we installed P1. we tried to optimize thetaX and thetaY of P1 and we clearly observed a strange motion when doing that

Alignment procedure, posted by Ronic Chiche at Optical room about mechanics | lasers and optics

Picture of the installed mirrors inside the FP cavity.

To install an Iris instead of a mirror :

One has to remove manually the orange nuts and replace the mirror mount with the Iris mount.

FP cavity alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

as the iris used to locate the FP-cavity axis have been removed before moving the table inside the Igloo, we have to find again this FP-cavity axis.

this morning with Viktor, we started to make the alignment of the FP-cavity with a red laser using only the "input window" iris mount
built by Yann.

FP cavity alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

This afternoon, we continued the alignment of the red laser.
we did it using the 2 final injection mirrors.
we still see a clear transmission after M2, a weak transmission after M3, and almost nothing after M4 due to the power loss going through the dielectric

FP cavity alignment, posted by Ronic Chiche at ThomX igloo about lasers and optics

A continuation of the alignment process was done, there was change in it due to variation in temperature,

it was done using the semiconducting laser, and we were able to obtain an output at M2.

2 references were placed before the alignment mirrors Ma and Mb , to fix the line when changing from semiconducting laser to CW "koheras"

Onefive ouput power and spectrum, posted by Lo�c Amoudry at Optical room about lasers and optics

After turning on, one can see the 133.33MHz Onefive output power for ~40min with OD2 filter (~/20). So the real output power is ~57mW. A measurment over
several days (15?) should come in few weeks.

The spectrum here has been taken one day after turning on the Onefive (see Fig. 133_spectrum_full and 133_spectrum). One can see the central

Onefive ouput power and spectrum, posted by Lo�c Amoudry at Optical room about lasers and optics

1) Note: The OneFive laser used for experimenting is the one for the SBox

but, for now only this laser arrived from the company so we are doing tests (measuring the spectrometer and power ) on it inside the ThomX cavity
clean room.

Beam size and finesse, posted by Lo�c Amoudry at Optical room about lasers and optics

FSR initiale : 33.34 MHz (S3 = -825000 et S4 = -825000)

Beam size initiale : wx=2.05mm et wy=2.15mm

Finesse initiale : 3400

Beam size and finesse, posted by Lo�c Amoudry at Optical room about lasers and optics

Measurement behind P4 (planar mirror)

Loïc
Amoudry wrote:

FSR initiale : 33.34 MHz (S3 = -825000 et S4 = -825000)

Coating reflectivity, posted by Lo�c Amoudry at Optical room about lasers and optics 6x

Coatings reflectivity curves and datas for HR Saphir, HR Suprasil and HR ULE.

Finesse measurement after the Edge installation, posted by Ronic Chiche at Optical room about lasers and optics

After the Edge installation inside the cavity, the Finesse has been measured several times by modulation technique with an average around 16000:
(the scan speed is 50kHz in 10 seconds.)

So, it hasn't changed since the last measurement in June, just before the Edge installation.

Finesse measurement after confinement, posted by Lo�c Amoudry at Optical room about lasers and optics

After 3 months without human presence, finesse has been measured 3 times with average optimization:
- 16150
- 16067

Pointing stability with CVBG, posted by Ronic Chiche at Optical room about lasers and optics

Pointing_stability_without_airflow_and_no_one_walking_around.png

Pointing_stability_without_airflow_vs_amplifier_current.png

Yesterday, with Titouan, we made some measurements on pointing stability of the laser beam after amplifier and CVBG.
the amplifier beam go through a first telescope to be small enough and colimated before going to CVBG's, then go to CVBG's and then is sent
through the FP-cavity telescope to the FP-cavity itself.

Amplifier laser diodes issue, posted by Ronic Chiche at Optical room about lasers and optics

This is a long time issue for the ThomX amplifier : on the 4 pumping diodes available, the 1st diode has a higher temperature than the others around
40°C (see the picture).
the problem comes from the TEC which is not activated (see diodes parameter files in execel format). the related software windows are shaded.

Optical spectrum before and after CVBG, posted by Ronic Chiche at Optical room about lasers and optics

Measurement of the optical spectrum with Avantes OSA before (1st picture) and after CVBG (2nd picture) with 2nd stage on the laser amplifier.
The 1st CVBG stretches the beam horizontally due to the default incident angle and the fact that different wavelength are reflected in the CVBG
with different depth.

Optical spectrum analyzer resolution, posted by Ronic Chiche at Optical room about lasers and optics

The Koheras @0.5mW is directly connected with fibers FC/APC -> FC/PC to the Avantes optical spectrum analyzer.

The FWHM wavelength, measured with the Avantes software, is 0.126nm

Optical spectrum analyzer resolution, posted by Ronic Chiche at Optical room about lasers and optics

Same measurement with Koheras @100mW and using fiber coupling lenses between Koheras and Avantes OSA.

The FWHM wavelength, measured with the Avantes software, is 0.116nm

Ronic

Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics

We installed the 2 CVBG for compression after the amplifier.
We used an interferometric technique with a delay line and combining the two paths in a CCD to measure interferences... see interferences.avi video
file

Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics

Yesterday, Loic installed a telescope before CVBG's to reduce the spot size on CVBG's and reduced the incident angle 0.5-1° on them (on the
datasheet the specified incident angle is 2.8°).

We used an interferometric technique with a delay line and combining the two paths in a CCD to measure interferences.

Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics

Yesterday, Loïc put the CVBG's back to their specified angles.

We used an interferometric technique with a delay line and combining the two paths in a CCD to measure interferences.

After supressing the global shape of the superposed pulses, one measures the amplitude of the remaining fringes (standard deviation) each 50µm

Beam pulse duration, posted by Ronic Chiche at Optical room about lasers and optics

Last Thursday (20th of February), Loïc and Titouan realigned the stretcher CVBG to its nominal angle and they used an interferometric technique
with a delay line and combining the two paths in a CCD to measure interferences.

After supressing the global shape of the superposed pulses, one measures the amplitude of the remaining fringes (standard deviation) each 50µm

Powerup with 2.5ps pulses, posted by Lo�c Amoudry at Optical room about lasers and optics

A power up has been performed on ThomX until 65kW intracavity power. We didn't see any modes but stored power was really unstable since ~60kW (see
image tek00004.png).

Measurement report is shown in the table below. Gain seems to decrease against intracavity power.

ThomX Locked with CVBGs, posted by Lo�c Amoudry at Optical room about lasers and optics

ThomX has been locked with a new telescope while using compression CVBGs.
Coupling is ~50-55% and lock is stable.

Power up to ~50kW should follow up soon (stop when HOM are observed). We'll not go over ~100kW to not risk any breakdown due to the

Telescope for compressors and ThomX, posted by Lo�c Amoudry at Optical room about lasers and optics

CVBGs telescope is done with w ~= 1mm.

ThomX telescope is done with w ~= 2.3mm in x and y.

Newt step is to lock with these short pulses (measured ~2.5ps with FWHM standard deviation interference method).

Onefive output power, posted by Lo�c Amoudry at Optical room about lasers and optics

The pump voltage has been increased few days ago when looking for a modlock of the laser.

The 33MHz Onefive output power is now 3.58mW with OD1 filter ==> ~36mW.

There are 2µW @ 1% coupling fiber with OD1 filter ==> ~20µW ==> 2mW @99% coupling fiber (2mW to the amplifier).

Onefive output power, posted by Lo�c Amoudry at Optical room about lasers and optics

Onefive output power measured today. 3.52 mW with OD1 filter ==> ~35mW.

Loïc
Amoudry wrote:

The pump voltage has been increased few days ago when looking for

CVBG reference and Eric Cormier calculation, posted by Lo�c Amoudry at Optical room about lasers and optics

The Stretcher is the "D 24-02-II", it must be used in double path before the amplifier injection.

There are two compressors in single path, "D 25-14-I" and "D 25-14-II".

Eric calculations are attached below.

30Hz noise issue, posted by Ronic Chiche at Optical room about lasers and optics | detectors and electronics

since some days, we observe the cavity is difficult to lock and a strange 30Hz noise has appeared on the PZT signal which normally compensate the phase
noise difference between the cavity and the laser.
to test if the problem could come from the laser, we changed the OneFive laser for the Koheras but we have exactly the same problem, thus we concluded

30Hz noise issue, posted by Ronic Chiche at Optical room about lasers and optics | detectors and electronics

The 30 Hz noise issue has been solved !

It came from translation stage of P1 and/or P4.

Fabian remembered that close to the mirror's mount translation stage end coarse, there is a mechanical instability. The mount kind of "lift

Pneumatic valves, posted by Lo�c Amoudry at Optical room about vacuum

The pneumatic valves are now plugged on the university air network.
The air valve is fully openned for the moment.
We still have to check if there is some minor leakage close to the pneumatic valve to improve the setup.

First Lock with 2nd satge of amplifier : Motor issue ? , posted by Ronic Chiche at Optical room about mechanics

Global locking almost clean : tranmission and reflection are quite noiseless except the peaks at every 500ms.

During the amplifier 2nd stage lock, we experienced 2 strange behaviors :

- short "unlocks" every 500ms exactly all the time, during the whole lock process

First Lock with 2nd satge of amplifier : Motor issue ? , posted by Ronic Chiche at Optical room about mechanics

The 500 ms noise disapeared. We had to disable the "power save" mode of the smaract translation stage. AND turn OFF and ON the controler box.

Ronic
Chiche wrote:

Global locking almost clean : tranmission and reflection are quite

Onefive Origami 33MHz specs, posted by Lo�c Amoudry at Optical room about lasers and optics 6x

Power during ~20h, power after turn on, spectrum image and excel datas, polarisation and pulse length.

Powermeter measurments were done with a /10 filter.. 3 mW means 30 mW

Important: Onefive does not automatically locks after being turned on.

Onefive Origami 33MHz specs, posted by Lo�c Amoudry at Optical room about lasers and optics

Beam Size Onefive added

Loïc
Amoudry wrote:

Power during ~20h, power after turn on, spectrum image and excel

Spherical mirrors at closest position. FSR, finesse and beam size., posted by Lo�c Amoudry at Optical room about lasers and optics

The spherical mirrors are at the closest position to get a FSR ~=33.3435 MHz. Planar mirrors are at the largest position.

The finesse has been measured about 17 000.

Beam diameter (2*w) is ~= 4.6 mm x and y.

First mode degeneracy on ThomX, posted by Lo�c Amoudry at Optical room about lasers and optics

Yesterday, we've observed the first degeneracy on ThomX cavity at ~115 kW stored. The shape of the stored power on the oscilloscope is really close
to what has been published in the D-shape mirror's paper ("tek0000" transmission in yellow, piezoelectric activator in green, error
signal in blue).

New locking scheme, posted by Ronic Chiche at Optical room about detectors and electronics

Before, the locking scheme was to produce an error signal with the PDH box, send its output to the electronic amplifier box and then to the laser EOM
for the fast loop and to the Laselock input. The drawback was changing one loop gain, changes also the other loop gain.

Now, the locking scheme is the error signal coming from the PDH box is directly sent to the Laselock input and in a same time to the electronic

First Lock with 2nd satge of amplifier : Finesse issue ?, posted by Ronic Chiche at Optical room about lasers and optics | detectors and electronics

1st lock today with the second stage of the amplifier.
~ 300mW of injected power (but which proportion of the pump and of the signal ? => One must use a spectrometer to determine this proportion)
MAYBE the real injected power of the signal is lower => maybe the Finesse is higher !

First Lock with 2nd satge of amplifier : Finesse issue ?, posted by Ronic Chiche at Optical room about lasers and optics | detectors and electronics

First of all, we used and optical spectrometer to determine which proportion of pump and signal is in the injected beam.
the wavelength is THE SAME for the 2nd stage for the beam coming from the core or coming from the clad !
thus, it is impossible to use a spectrometer to obtain this proportion.

Onefive spectrum and CVBG spectrum, posted by Lo�c Amoudry at Optical room about lasers and optics

The Onefive spectrum has shifted a little bit to lower lambda. It's still enough for the experiment (3mW injection of ampli intead of 1mW needed).

Fiber injection and onefive output power, posted by Lo�c Amoudry at Optical room about lasers and optics

Fiber injection is finished with the new ThomX stretching CVBG in double pass (+50% injection power compared to K-BOX CVBG in simple pass).

- Output Onefive: 27 mW
- After Onefive + lambda/2 + isolator: 25.8 mW

Free Spectral Range (FSR), posted by Lo�c Amoudry at Optical room about lasers and optics

FSR is 33.347 MHz @1e-8 mbar

Improvement holder amplifier fiber, posted by Lo�c Amoudry at Optical room about lasers and optics

We've added a clamp in the 3rd stage to prevent the pump fiber from moving and tilting (it was tilting to the left).

ThomX amplifier M2, posted by Lo�c Amoudry at Optical room about lasers and optics

The ThomX M2 has been measured between 1.5-1.6 for x and y

Electrical trouble (disjunction), posted by Lo�c Amoudry at Optical room about cabling

The circuit breaker on ThomX cavity drops @1.5-1.8kW when we turn on 1/2nd stage of the amplifier or 3rd stage of the amplifier.
Amplifiers are now connected to K-BOX UPS.

We are buying a clamp ammeter for further investigations.

Cavity under vacuum , posted by Lo�c Amoudry at Optical room about vacuum

The cavity is right now at 6.5e-8 mbar (turbo pumps on for 1 night and ionic pumps for 3h), primary pumps and turbo pumps are cut, ionic pump are on
and the pressure level is still going down.
Therefore there aren't any big leak in the cavity and we can expect a final vacuum level close to e-9 mbar.

Pneumatic valves, posted by Lo�c Amoudry at Optical room about mechanics

Frederic and Manu from vacuum group came this morning to fix again the pneumatic valves which had a leak again.

Finesse measurement, posted by Ronic Chiche at Optical room about lasers and optics

After mirrors were going back from LMA for cleaning and thermal anealing, they have been installed in FP cavity for Finesse measurement.

after getting strange results when the cavity is closed (very low Finesse...maybe too much ethanol inside cavity procucing some lineic losses),
we get 12k-12k5 Finesse with primary vacuum (~4 mbar) and a clean lock (very flat transmission signal and quite noiseless reflection signal)

Finesse measurement, posted by Ronic Chiche at Optical room about lasers and optics

To complete these observations:

Finesse has been measured on thursday, right after cleaning the cavity with ethanol @6000.
Finesse has been measured on friday, after opening the cavity for few tens of minutes @12000-12500. The cavity was openned while

Diffusion ULE spherical mirror (S3) vs Fused Silicate injection planar mirror (P1), posted by Lo�c Amoudry at Optical room about lasers and optics

Observation made with IR Beam Viewer:

The observation of P1 and S3 simultaneously while locking shows much higher diffusion on the ULE mirror. The diffusion on the two other ULE mirrors
(S2 and P4) shows similar diffusion as S3.

New Suprasil mirror from LMA, posted by Lo�c Amoudry at Optical room about lasers and optics

14/05/19:

New Suprasil mirror received. It will replace the S-BOX suprasil mirror on ThomX which was already replacing the sapphire mirror.

First finesse measurement: 14000

New Suprasil mirror from LMA, posted by Lo�c Amoudry at Optical room about lasers and optics

19/09/2019 : email from Chrisophe Michel about AR coating of LMA mirrors after reading that Ta2O5 layers can be damaged in vacuum if not protected by
a SiO2 layer :

"oui tous nos coating standards HR se terminent par une couche de protection SiO2 Lambda/2.

Motor issue, posted by Ronic Chiche at Optical room about mechanics | detectors and electronics

Today, Axis 9 (Z-axis of P1) has blocked the software which drives all the motors.
impossible to bypass the problem.

I had to :

Motor issue, posted by Ronic Chiche at Optical room about mechanics | detectors and electronics

Today again, same problem with axis 9 blocking the controlling software during the mirror alignment procedure.

after opening the motor 9-16 controlling crate, we saw 2 screws (RX- and TX+ of the controller) which were badly screwed.

we firmly screwed them... could it be the cause ?

Cavity dust source check, posted by Lo�c Amoudry at Optical room about mechanics | lasers and optics

Several experiments have been done in order to check the potential source of dust in the ThomX cavity. For each step, we look at a clean surface, put
the cavity under vacuum, go back at ambient pressure and check back the "clean surface".

1st: Primary pump on

LMA cleaning technique, posted by Lo�c Amoudry at Optical room about lasers and optics

Christophe MICHEL told us more precise informations about spin coater cleaning.

They always clean with pur water and cotton tipped sticks.
First a spray of water, then they put the wet cotton tipped sitck onto the mirror from the center to the edge ~x3 while continuing to spread

Primary vacuum to check dust, posted by Lo�c Amoudry at Optical room about mechanics | vacuum

The cavity has been cleaned then put under primary vacuum (primary pump without vacuum flow control). Dusts presence was checked at air and no significant
changes have been observed.

1ST image before cleaning

Mirrors sent to LMA, posted by Lo�c Amoudry at Optical room about lasers and optics

Mirrors have been sent today to LMA for cleaning and maybe annealing (recuit). 3 ULE of ThomX and the fused silicate for injection (trans @140ppm ).

Finesse measurement after mirror cleaning using the spin coater, posted by Ronic Chiche at Optical room about lasers and optics

Last Finesse measurement in air : ~ 17 000 the 20th of may (see logbook)

28th and 29th of august, we cleanned, with Loïc, mirrors S3 then P1 successively using only ultra pure water with the spin coater.

we measured the finesse after each cleaning by modulation technique and in both cases, F ~ 12 500 !!!

Finesse measurement after mirror cleaning using the spin coater, posted by Ronic Chiche at Optical room about lasers and optics

today I cleaned S3 with isopropanol and then with pure water on spin coater.
Finesse is only 10 700.(coupling 50% ? => to be confirmed...)

maybe we have to redo the procedure with a different way of cleanig (pushing less on the mirror ... ?)

Finesse measurement after mirror cleaning using the spin coater, posted by Ronic Chiche at Optical room about lasers and optics

Following finesse measurements (start @10700):
Clean P1 with SC (water) + isoprop (wipe) finesse @15000
Clean S2 with SC (water) + isoprop (wipe) finesse @13000

Vessel cleanliness, posted by Ronic Chiche at Optical room about mechanics | lasers and optics | vacuum

looking in the vessel of the FP cavity using a UV lamp shows a lot of dust... more dust than outside the cavity !!!

here is picture where one can see a cleaned zone using a finger (with gloves).

question : where does come from this dust ?

Spin coater air supply removed and front panel changed, posted by Lo�c Amoudry at Optical room about mechanics | lasers and optics

Spin coater firstly needed vacuum and air supply. The air supply being useless for our experiments, it has been disabled.

The process is the following and is reversible:

1) Remove the hub from the top of the spin coater, (see picture 1), 4 screws

2nd stage output power validated , posted by Lo�c Amoudry at Optical room about lasers and optics

Onefive output power : 28mW
Power before fiber injection : 7.8mW
After EOM and 99% coupling fiber : 1.8mW

Onefive 33MHz unmodelocked, posted by Lo�c Amoudry at Optical room about lasers and optics

Oscillator randomly unmodelocked on 3rd july afternoon (during oscillator power measurement, maybe a reflection from the powermeter power filter
?)

Modelocked this afternoon by putting Onefive motor and phase at reference on the PTC software.

New design for PDH boxes, posted by Ronic Chiche at Optical room about detectors and electronics

A new design has been studied for the 5 PDH boxes to better match the low (33MHz) repetition rate of the ThomX laser.
the 5 PDH boxes have been modified and tested (see the attached report).
A mixer has been integrated to the PDH box for a more simple use.

telescope for Koheras, posted by Huan Wang at Optical room about lasers and optics

telescope of Koheras is removed, information record here:

- distance between collimator edge and -50 lens mount edge is 14.7cm,

- distance between another edge of -50 lens mount and +250 lens mount edge is 14.3cm,

Polarization, posted by Lo�c Amoudry at Optical room about lasers and optics

Polariztion measured with Input vertically/horizontally polarized (~100% DOLP)

- Transmission (P4) locked on cavity horizontal polarization is ~50% linearly polarized and ~50% unpolarized ?

- Transmission (P4) locked on cavity vertical polarization is ~50% linearly polarized and ~50% unpolarized ?

Amplifier mission Bordeaux, posted by Lo�c Amoudry at Other about mechanics | lasers and optics

Voyage Bordeaux au CELIA avec Jérôme LHERMITE (Loïc et Titoutan)

1er jour (34°) :

Mesure du spectre et de la puissance des 4 diodes de pompe 3ème étage jusqu’à ~60W (12A).

Amplifier mission Bordeaux, posted by Lo�c Amoudry at Other about mechanics | lasers and optics

M² mesuré à 10W.
M²x = 1.17
M²y = 1.14

Transmission of Sapphire mirror, posted by Lo�c Amoudry at Optical room about lasers and optics

See image.

Finesse measurement by decay time technique, posted by Ronic Chiche at Optical room about lasers and optics

2019-05-21_-_Finesse_measurement_by_decay_time_technique.docx

5 Files attached:

- Note on the technique and results for the present cavity on 2019, May 21th : F ~ 18 000

- 2Tektronix scope raw data

Finesse after cleaning (new suprasil mirror), posted by Lo�c Amoudry at Optical room about lasers and optics

15/05/19-20/05/19:

Cleaning of the mirrors:

Initial finesse 14000 @air

33MHz Onefive power overtime decrease, posted by Lo�c Amoudry at Optical room about lasers and optics

Power of the 33MHz Onfive decreases over time. Have to pay attention to that.
Note that air dryers have never been stopped.

10th april 2018: ~40mW (first picture, 10dB filter)

Injection of 33MHz Onefive through fiber, posted by Lo�c Amoudry at Optical room about lasers and optics

power_after_halfwaveplate_and_injection_and_point9dB_blue_fiber.PNG

power_after_halfwaveplate_and_injection_and_point9dB_blue_fiber_and_EOM_NIR-MPX-LN-0dot1.PNG

power_after_halfwaveplate_and_injection_and_point9dB_blue_fiber_and_EOM_NIR-MPX-LN-02.PNG

Output power of the Onefive, and power after injection and different components have been measured.

Coupling ~= 90%
Each of our two EOM roughly have the same loses ~3dB

Mirror's cleaning and finesse, posted by Lo�c Amoudry at Optical room about lasers and optics

Summary of what have been cleaned the last week:

P1 with isopropanol, finesse 11000
P4 with isopropanol, finesse 13000

P4 cleaned and finesse measurement, posted by Lo�c Amoudry at Optical room about lasers and optics

P4 cleaned with isopropanol.

Finesse measured afterward: ~=13 000 (clear increase)

Finesse after 2days, posted by Lo�c Amoudry at Optical room about lasers and optics

Finesse measured this morning after P1 SUPRASIL being into the cavity for two days. In order to check if it's getting dirty.

Finesse still ~= 11 000

Finesse with P1 SUPRASIL, posted by Lo�c Amoudry at Optical room about lasers and optics

P1 SUPRASIL has been installed instead of P1 Sapphire. It has been cleaned 3 times on each face with wipe+isopropanol before to be installed.

Finesse ~= 10 000 - 11 000 (EOM Sweep of 100 kHz in 10sec, see last image.)
Coupling ~= 45%

Transmission of the mirrors, posted by Lo�c Amoudry at Optical room about lasers and optics

We openned the cavity, removed S2 and measured trans of P1 and same for S2.

Pin ~= 3.91 mW
PS2 ~= 20 nW --> ~~ 5 ppm !!!

Transmission of the mirrors, posted by Lo�c Amoudry at Optical room about lasers and optics

After verification, transmission of P1 correspond to ~150ppm.

The 1337ppm come from a beam leakage. Reflection from P1 goes to the input window which reflects again a part of the beam directly into the cavity
between P1 and S3 then between P4 and S2.

Transmission of the mirrors, posted by Lo�c Amoudry at Optical room about lasers and optics

P1 transmission out of the mount (means angle of the mirror is not the real angle):

Pin = 3.2 mW
Pout = 545 nW

Beam size at closest spherical mirrors position, posted by Lo�c Amoudry at Optical room about lasers and optics

S3 and S2 @ +1 640 000 and P1 and P4 @ -825 000

Diameter in x: 4.7mm
Diameter in y: 4.7mm

Finesse after removing wires, posted by Lo�c Amoudry at Optical room about lasers and optics

19/04/01: We removed the wires from the beam path in the cavity. Finesse stayed at 3400. FSR: 33.342 MHz.

When locked:

Input Power: ~4mW

Motors Z axis reversed, posted by Lo�c Amoudry at Optical room about mechanics

S2 and S3 z-axis are initially at 1/4 (5mm/20mm) of there range over ~20mm range. This is meant to be able to spread them up to ~15mm in case of
thermal effect.

Actually, they are in an opposite position. Means that they can only be spread of 5mm from the initial position.

Motors Z axis reversed, posted by Lo�c Amoudry at Optical room about mechanics

All Z motors (for P1, S2, S3 and P4) have been initialized again with a proper HOME command with their own controller with the "superviser"
software (which means they all moved to the +1650000 position).
Thus, they have been moved to their default position : +825000 for spherical mirrors (S2 and S3) and -825000 for plan mirrors (P1 and P4).

Wires in laser path, posted by Lo�c Amoudry at Optical room about mechanics | lasers and optics | cabling

There was some ceramic wires close to the beem path right before P4. We moved them away (we can imagine they could move again with vibration).

Check of mirrors and coating directions, posted by Lo�c Amoudry at Optical room about lasers and optics

Direction of HR face of P1 and P4 have been checked, there was no problem. The mirrors are in the good direction and the coating is on the good face.

Once P1 and P4 outside of the cavity, we checked the coating position by sending the HeNe laser with an angle. There was two reflections and
the most intense was the one closer to the normal to the mirror.

Cavity at atm pressure, posted by Lo�c Amoudry at Optical room about lasers and optics | vacuum

Dry air injected into the cavity.

Lock has been proceeded without any trouble. ~~4000 finesse. Considered to be the same than before.

x and y motors axis put back to the last "cavity at air" position. z position kept at maximum distance between spherical mirrors.

Motors connexions, posted by Lo�c Amoudry at Optical room about mechanics

Motors are connected. The true mirror's name are P1 for injection mirrors, S2, S3 and P4. (S=spherical, P=planar).

They are still some old schemes (and notations on the cavity) which mention M1, M2, M3 and M4. I make the link here:

M3 = P1

Basic alignment & alignment motors check, posted by Lo�c Amoudry at Optical room about mechanics | lasers and optics

14/02/19: The 4 motors but Mby control works. Mby motor home does not bring it to its "middle" position but to the end of its range.
Issue circumvented using the higher rights software.

The beam is now going through the cavity windows (from P1 to S2).

Mirrors sent to LMA, posted by Lo�c Amoudry at Other about lasers and optics

30/01/19 - As LMA people came, we discussed about the spots on ThomX mirrors which should be clean. As mentionned in "SBOX commissioning",
these spots are normal.

An other question appeared during the conversation about the storage time and location of these mirrors. They have been stored for more than

Mirrors checked with binocular microscope, posted by Lo�c Amoudry at Optical room about lasers and optics

29/01/19 - ThomX mirrors have also been checked with binocular microscope. They shown the same spots as S-BOX mirrors.

1st image shows reflective face of a spherical mirror.

2nd image shows reflective face of M1 (sapphire).

End of cleaning, plastic fixed on cavity, posted by Lo�c Amoudry at Optical room about utilities

08/02/19 - End of the cleaning process.

Cleaning outside IP cavity, posted by Lo�c Amoudry at Optical room about lasers and optics | utilities

Apres_une_semaine_nettoyage_lingettes_et_brosseadents.jpg

From 7th january to 11th january.

End of vacuum test and cavity ready for cleaning, posted by Lo�c Amoudry at Optical room about vacuum

Vacuum tests finished on 19 december 2018.

Spent last two days to discuss the importance of removing aluminium and baking wires before to insert mirrors for cleanliness issues. Finally
we took pictures to support our demand.

Etuvage cavit� THOMX, posted by Ronic Chiche at Optical room about vacuum

Mail de Bruno Mercier du 19/11/2018 :

Une première cavité a été étuvée, la pression est actuellement de
3.10-10 mbar, l' étuvage
de la deuxième cavité vient de commencer et se
finira en début de la semaine prochaine.

Bonne journée,
Bruno

Remontage des v�rins, posted by Ronic Chiche at Optical room about mechanics

Mail de Yann du 8/10/2018 :

Bonjour,
Tous les vérins sont maintenant OK ! Merci Ronic.

Remontage m�canique, posted by Ronic Chiche at Optical room about mechanics

Mail de Yann du 12/10/2018 :

Je vous fais le bilan des actions effectuées :

1/ La mécanique a été remontée avec changement des billes céramiques, soufflet défectueux, ect...

D�tection de fuite, posted by Ronic Chiche at Optical room about vacuum

Mail de Bruno Mercier du 18/10/2018 :

Un petit CR de la journée:
Nous avons effectué une détection de fuite sur l'ensemble des cavités optiques. Une fuite très importante a été

test des v�rins ISP 20mm et 6mm, posted by Ronic Chiche at Optical room about mechanics | cabling

Après avoir utilisé la chaine : driver ISP - cable ISP DB9 - Feedthrough enceinte DB9-DB9 - cable perlé DB9-SUB-C - Capsule SUB-C,

l'ensemble de tous les vérins 6mm et 20mm ont été testés => ils fonctionnent TOUS.

Les vérins 6mm ont TOUS subis un HOME. cette commande cherche une fin de course du vérin et le place ensuite en position médianne.

test des v�rins ISP 20mm et 6mm, posted by Ronic Chiche at Optical room about mechanics | cabling

Ronic
Chiche wrote:

Après avoir utilisé la chaine : driver ISP - cable ISP

test des v�rins ISP , posted by Ronic Chiche at Optical room about mechanics | cabling | software

* les vérins de 20mm (axe Z) ont été testés sur table grace à une rallonge SUB-C - DB9, au chassis ISP et au soft
SUPERVISEUR écrit en labwindows CVI par Didier.

pour rappel, la course soft va de -1 650 000 à +1 650 000 pour 20mm de course, soit 0.6mm pour 100 000 de course soft.

test des v�rins ISP , posted by Ronic Chiche at Optical room about mechanics | cabling | software

Ronic
Chiche wrote:

* les vérins de 20mm (axe Z) ont été testés

Onefive Origami 33MHz specs - Polarisation, posted by Ronic Chiche at Optical room about lasers and optics

one rotate a lambda/2 before a PBS and meausure the refected power:

Pmax=35.6 mW

Pmin=107 µW

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