Sheila, Camilla.
We decided to pause on looking for the FC alignment and look at SQZ alignment into the IFO. To check our irises and possibly look for scattering shelves.
Locked SEED_DITHER with 75mW into fiber. Moved ZM3 to get OPO_IR PD up to max 0.9mW. Opened BeamDiv and after aligning SRM, mis-aligning SR2, could see beams on AS_A,B and C. AS_A and B had a similar size ~60 to reported before (e.g. 86965), but there was less power on AS_C: 4e-4 rather than the previous 7e-4.
We used Ryan's DRMI time from 89573 to put OM1, OM2 and SRM back. The with the SQZ SEED injected, we tried to use SQZ centering loops to center on AS_A and AS_B, this didn't work quite as expected. ZM4 kept saturating although these loops had worked Janaury 19th, before moves were done on the VOPO to help with clipping e.g. 88966.
Then went back to alignment on Jan 31st with 88976 with ZM1,2,3, 4,5,6 FC1. And took OM1,2,SRM to the January 19th positions. However here we saw no light on SQZT7 OPO IR PD, HAM7 WFs or in HAM6 on the AS_A,B,C diodes. This was done at 23:10 UTC. Comparisons of osems attached. The sliders to get these osems values are fairly different, see attached, so I also tried going to these slider values, that gave me some light on SQZT7 IR PD, HAM7 WFS and FCES with SEED injected, see attached. HAM6 AS diodes saw nothing.
Sophie, Camilla
This morning, starting from this vented slider alignments, I randomly moved ZM1 until we had IR and green light on the FCES PDs. I misaligned FC1 and FC2 to single pass light. Then I could move ZM3 in pitch from P,Y (-324,-200) to (-506, -200) to get max light on IR FCES PD. In both these positions, we get scattered light on the camera and light on both IR and green PDs. This makes me think the best position in pit h is in the middle of these, ZM3 (-415, 200). We tried to repeat this excise in yaw but only could get the one edge. Even after movingZM1 in YAW in both directions, I couldn't find the other side of the yaw clipped beam. Attached is the sliders when we thought we were centered in pitches and clipping the coating on one side in yaw.
We need 4 things for the squeezer to operate:
- Filter cavity green sensing (FCGS) reaching SQZT7
- IR reflected off filter cavity making it back through VIP without clipping (IR on SQZT7)
- IR flashes in filter cavity
- Green flashes in filter cavity
Continuing from where Sophie and Camilla left off, I confirmed that the green I see on the FCES green camera is a single pass beam by misaligning both FC1 and FC2, they do not move this beam, and also confirmed that it's green by toggling the fiber input. I moved ZM3 to bring this to center on the camera, as we have not disturbed this FCES green path since O4. Then I did a raster on FC1 to get the IR seed reflected onto the SQZT7 IR PD (screenshot).
After moving FC2, I could see some green and IR on the FCES cameras. For IR, this is not the single pass beam but some reflections off FC1, for green we still see the single pass beam and a second beam coming close to the single pass beam, but it seems to have a very different beam size. screenshot. After this I went to SQZT7 and saw that the FCGS refl beam is making it to the table and aligned it onto the diode. Now we have 2.5 of the 4 things we need for the squeezer to work: green on SQZT7, IR on SQZT7, and the green single pass is heading towards FC2 well, which is part of what we need to get green flashes.
Sophie and I went to FCES. We tried moving FC2 to see what happened on the green transmission, we can see the beam reflected off FC2 leaks around the edge of the FC2 coating for some alignments, but that we can overlap them for some alignments, but do not see cavity flashes.
Camilla moved ZM3 back to the alignment where she found the green centered between the two places where it goes over the edge of the coating. This was a simlar situation in green.
In IR, we did see a single pass beam on the camera when Camilla steered ZM3. In 986 ZM3 is in the position where Camilla thinks IR is centered on FC2, you can see two green spots, and to the right and slightly below a very faint IR beam (I had to clean the laptop screen, turn the brigthness up to see it). In 988 ZM3 was at -506 P, -200 Y, the negative pitch clipping, you can see the brighter IR beam where it is transmitting through the uncoated part of FC2. 990 is ZM3 -324 P, -200 Y, going over the lower edge of the coating. 994 is with FC1 + FC2 in the aligned guardian state, moving FC2 until we saw something on the IR camera. 996 is for FC2 359 P, 28 Y, there was light on the IR diode, but the photo is dark.
