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Reports until 18:39, Tuesday 20 February 2024
H1 SQZ
naoki.aritomi@LIGO.ORG - posted 18:39, Tuesday 20 February 2024 - last comment - 13:55, Wednesday 21 February 2024(75902)
PMC is locked with s-polarization

Nutsinee, Vicky, Daniel, Naoki

We brought back the SQZ laser power (PMC input power) from 30mW to 670mW and locked the PMC with s-pol. The PMC trans power is 420mW and the PMC transmissivity is 60%. So all the power downstream of PMC reduced by 40%. The PMC TRANS DC POWERMON is calibrated into 420mW.

Then we aligned SHG. The SHG mode matching is 82%, which is slightly lower than before.

To increase the SHG IR injection power, we adjusted HWP for SHG path. The SHG IR injection power is now maxed out at 200mW. The SHG GR DC POWERMON is 37mW, which is lower than before 40-60 mW.

To increase the CLF power, we replaced the pick off mirror just before the CLF fiber from R=10% to HR mirror. The CLF power before the fiber is 135uW and the CLF REFL power in SQZT7 is 20uW. The CLF LAUNCH DC POWERMON is calibrated into 135uW.

Comments related to this report
nutsinee.kijbunchoo@LIGO.ORG - 00:37, Wednesday 21 February 2024 (75904)

Attached a quick power budget note of the current SQZT0, a new SHG scan, and a PMC transfer function locked with s-pol (2.3 kHz UGF). CLF alignment into the AOMs isn't great at the moment. We replaced MR5 with a mirror instrad of a 10% reflective optic. Seed and Pump fiber alignment hasn't been touched. A proper drawing to follow.

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nutsinee.kijbunchoo@LIGO.ORG - 13:55, Wednesday 21 February 2024 (75916)

Squeezed in a few more power measurements before the Corner Station Boost Fest. It appears we have lots of back reflection rejected by the FI. The green could have confused the power meter that is set to 1064. Next time we could put a narrow band filter on to measure exactly how much green is coming back towards the FI instead of the launch fiber. 

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