Ryan S, Sheila, Eric O, Camilla, Keita. Follow on from 90698.
This morning Sheila and Eric adjusted the SQZ IFO ASC to run centering loops from AS_A and AS_B to ZM4 and ZM5, in preparation for running OMC scans with a variety of psams settings. See attached.
Starting trying to take OMC scans with the SQZ beam, with less misalignment than we saw in 90615, to eventually use Begum’s scripts to repeat with different PSAMS settings.
Sheila and Ryan, went to the misalignment peak with the PZT offset and then started a dither over it and tired to change OM3 and OMC alignments but couldn't reduce the size of the beam, only make it worse. They undid the SRM alignment change, this did not help.
Sheila and Keita then tried to lock the OMC on the 00 mode, as in 80010 but it was not stable. Sheila then put a dither on the OMC PZT and we maximized the TEM00 peak with OMC and OM3 SUS, we improved the flashes 10%. OMC from (P-1900, Y -400) to (P -1300, Y -480) and OM3 from (P -1400, Y +95) to (P -1400, Y +65). The OMC scan after that was at a much better alignment, see data attached and below. Strangely this is showing worse mode mismatch than the the alignment was poor in 90615.
Shortly after this HAM5 and ZM6 WDs tripped (CPS WD trip) and afterwards, the OMC scan alignment was poor again. Sheila made some progress on getting the code to work /userapps/release/sqz/h1/scripts/HAM6_related/ham7_psams_sweep_QPD_center.py, but more work is needed.
| PSAMS | Dark | TEM00 | TEM02 (Mis-match) | TEM01 (Misalignment) |
Mismatch*
(% of TEM02)
|
| ZM4 6.2V, ZM5 -0.4V | 0.0209615 | 0.620414 | 0.0397442 | 0.0409605 | 3.04% |
*calculated with TEM02 / (TEM00 + TEM02)
We tried changing PSAMS while SQZ ASC was on, it took 30s to settle. The misalignment peak did change between scans but only a small amount. Misalignment peak was around 8.5% and then 10% of 00 peak.
We did not manage to get back to the lowest misalignment as above, even with dithering PZT2 around the 00 peak and maximizing with OMC and OM3.