Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software 
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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 |
33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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) |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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. |
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Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software 13x
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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 |
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Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software
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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. |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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. |
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Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software
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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 |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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 |
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Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software
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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 |
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Cavity Lock - Alphanov Amplifier , posted by Manar Amer at ThomX igloo about lasers and optics | detectors and electronics | cabling | software
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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!!!!!!!!) |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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 |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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 : |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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 |
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First X rays and FP-cavity mode and electron beam waists size @ IP, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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 |
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Incoming laser beam power issue, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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. |
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33MHz oscillator + Alphanov amplifier lock, posted by Ronic Chiche at ThomX igloo about lasers and optics
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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 |
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lock oscillateur 33MHz - synthé 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics
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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. |
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lock oscillateur 33MHz - synthé 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics
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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. |
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lock oscillateur 33MHz - synthé 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics
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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. |
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lock oscillateur 33MHz - synthé 500MHz, posted by Ronic Chiche at Optical room about detectors and electronics
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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. |