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
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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. |
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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
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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 |
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 
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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. |
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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
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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 |
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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
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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 |
Finding correct motors position and parameters to keep the lock during a move, posted by Ronic Chiche at ThomX igloo about mechanics
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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 |
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Finding correct motors position and parameters to keep the lock during a move, posted by Ronic Chiche at ThomX igloo about mechanics
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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 |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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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. |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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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. |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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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). |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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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. |
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Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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) |
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Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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 |
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Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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 |
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Onefive 33MHz modelock loss, posted by Ronic Chiche at ThomX igloo about lasers and optics
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For the modulation/demodulation generator for the PDH signal,
after a power shutdown, on can :
1) restart the generator to get the correct parameters: |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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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.
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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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 ? |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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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 |
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Optimizing lock parameters for stable X-ray production, posted by Ronic Chiche at ThomX igloo about lasers and optics | software
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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. |
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Checking the amplifier power, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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). |