Reports until 16:28, Friday 07 October 2022
H1 TCS
thomas.shaffer@LIGO.ORG - posted 16:28, Friday 07 October 2022 - last comment - 09:35, Tuesday 17 January 2023(65264)
TCS CO2Y Laser Swap

Summary: The spare laser was sucessfully swapped in and aligned to irises and the FLIR camera, BUT it's only outputting 31-34W.

Camilla and I continued the TCS laser swap from where we left off yesterday (alog 65248), with Marc helping us get the AA chassis swapped. After that, the laser fired up without issue and the thermopile at the head reported 47W. We aligned the beam to the three irises on table using the M1 and PM1 mirrors (table layout) and used some before images on the FLIR camera as a referance as well. We also double checked the beam dumps all still dumped, masks looked good, and the flippers functioned correctly. One of our final checks was to check the power coming out of the laser itself. We used a Thorlabs S314C and a Thorlabs S322C, they reported 31W and 34W max power after the M1 mirror. This is much lower than we expected, the calibration for the thermopile at the head must be different for this laser or maybe it just isn't working properly. Either way, this is a bit more power than we had before.

Next week we will try swapping the RF signal generator and maybe continue further with RF investigations to verify this isn't a problem as well. We left the beam dump before the periscope so we can test while in a laser safe state next week, but we did key OFF the lasers for now.

Comments related to this report
camilla.compton@LIGO.ORG - 11:11, Tuesday 11 October 2022 (65296)

Both lasers come on noisy and stabilized after being locked by the CO2 guardians. See attached.

The discrepancy between power measured by the laser head and power we measured using an external power meter for CO2Y comes from us not recalibrating the H1:TCS-ITMX_CO2_LSRPWR_HD_PD "Watts" filter. ITMX gain = 8.58755, ITMY gain = 13.96. We'll update this ITMY filter when next in laser hazard.

Images attached to this comment
camilla.compton@LIGO.ORG - 16:18, Tuesday 11 October 2022 (65301)

Spare installed was 20510-20816D, refurb datasheet is attached to the ICS record.

camilla.compton@LIGO.ORG - 12:48, Wednesday 19 October 2022 (65393)

I left the laser locked 6 days ago and yesterday afternoon it re-locked with a higher temperature which seemed to increase the output to the laser by 35%! See attached but note the LSRPWR number has not yet been calibrated. We previously measured ~32W out so now expect 43W out. We will confirm this by measuring and calibrating with an external power meter. We can work on increasing the temperature further and try a warmer temperature for CO2X as well.

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