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)
0 0.7
10 1.65
20 13
30 25
40 37.7
50 50.5
60 62
70 74
80 86
90 99
100 110
we had an alarm @100% of amplifier ratio => the reason is not clear... maybe it's coming from a discrepency between some internal measurement and the expected value.
we checked the power after the alarm => still OK
conclusion, the amplifier seems to be OK... we need to redo the alignment of the compressor CVBG.
| Ronic Chiche wrote: |
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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
| Ronic Chiche wrote: |
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this morning with Daniele, we are measuring the amplifier power just before the FP-cavity.
Casemate temperature @19.5°C
@0% : 205mW
@10%: 755mW
@20%: 7.44W
@30%: 14.3W
@33%:16.3W
@40% : 20.3W
@50% : 24W
@60% : 26W
=> there is a power issue !!!
the normal casemate temperature should be in between 21 and 22°C.
cf this post (https://elog.lal.in2p3.fr/FPC/THOMX+commissioning/133) to get previous amplifier power.
=> it seems we need to redo the compressor CVBG alignment !
first, we will check the amplifier power before the compressor.
| Ronic Chiche wrote: |
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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)
pb : I don't see the 500MHz beating signal => to be checked
during the motion of the FP-cavity motors, I observed a systematic delock when moving MOT.06 on P1z and no delock with MOT.03 on P4z when I move by 10 steps.
Kevin checked that both IcePap controller have the same configuration and then, the problem is maybe coming from the rust observed on the mechanic.
| Ronic Chiche wrote: |
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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.
the coupling (the cyan color) is ~ 62% !
=> we need to do some alignment
| Ronic Chiche wrote: |
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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 !
the photodiode connected to the scope CH2 is around 210mV @ 50ohms
we clearly see some small peak on the transmission signal (scope CH1) => we need to optimize the laser cavity length and the CEP
| Ronic Chiche wrote: |
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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
then, I connected the fiber of the EOM to the Alphanov amplifier input fiber.
LAL Alphnov software :
PD_IN = 3.289mW
PD_PULSE = 33.372MHz
=> nothing to do ! :-)))
I switched ON the preamplifier (3rd stage @ 0%) => PD_Preamp2 = 152.44mW
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