Reports until 18:52, Wednesday 24 August 2022
H1 AOS (SQZ)
aaron.jones@LIGO.ORG - posted 18:52, Wednesday 24 August 2022 - last comment - 14:49, Friday 26 August 2022(64677)
Swapped SK and FCGS Paths in SQZT7 
Vicky, Dhruva

We aligned and swapped the SK and FCGS paths compared to https://dcc.ligo.org/D2000242-v1. The PD cables were swapped accordingly and the entire motorised waveplate assembly was swapped too. The entire FCGS REFL path is now nearer the door for easier access.

We also installed FC_BEAT_RF1, as a PDA100A2 as speciffied in T1600605. S/N: TP02010820
Comments related to this report
victoriaa.xu@LIGO.ORG - 14:49, Friday 26 August 2022 (64695)SQZ
Link

SK path seems to be working; when setting the 2nd FC AOM2 VCO to +80.000100 MHz (while FC AOM1 set to -80MHz), we see phase noise on the FC BEAT note around 100 Hz. Makes sense, this path beats FC_REFL vs OPO_GR_REFL, both of which are ~at the SHG frequency. Beatnote can probably be optimized with in-vac picos, and clipping reduced by dropped the perioscope mirror as Camilla notes (64680).

Also calibrated FC_BEAT_REJECTED and FC_REFL_REJECTED photodetectors, saved to SDF.

  • FC_BEAT_REJECTED -- At 0dB, saw 1V for 250uW measured on Thorlabs power meter. Calibrated by setting: Responsivity (A/W) = 0.24, Transimpedence (Ohms) = 17,500.
  • FC_REFL_REJECTED -- At 30dB setting, saw 0.02V for 1.36uW on Thorlabs power meter, w/Transimpedence fixed in beckoff at 2000 Ohms. Calibrated by setting: Responsivity (A/W) = 0.3
    • FYI this FC_REFL_REJECTED screen its Beckoff screen as expected, but also shows whitening gains but no fast filter bank.
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