work with HV voltage on the Laselock, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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 |
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Fast feedback loop between laser and FP cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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) |
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Fast feedback loop between laser and FP cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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. |
some changes in the feedback scheme, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics 
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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). |
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33MHz (FP-cavity vs RF) phase stability, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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 |
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33MHz (FP-cavity vs RF) phase stability, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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 |
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FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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 |
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FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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. |
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FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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 |
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FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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. |
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FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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. |
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FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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this morning, the chiller was in error and I had to restart it.
the air temperature is around 21°C. |
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FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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... |
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FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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: |
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FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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. |
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FP-cavity lock survey during the Linac section changing operation, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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. |
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fixing CVBG issue, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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 |
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fixing CVBG issue, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics 12x
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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 |
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fixing CVBG issue, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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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. |
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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). |