Sheila, Camilla, Sophie
Following Sheila's finding last week that the nominal ZM2 PSAMS settings of 3.15 V is giving us an oval beam, 89675, we set ZM2 PSAMs to 4.5V and immediately got better flashes in green and IR on FCES. Moved ZM2 to increase flashes to be ~55 on green PD C and occasionally up to 1.2 on IR PD D with CLF injected.
Sheila could lock green FC for ~10 seconds. With the SEED injected it did not seem to be co-resonant and she needed to turn off SUS feedback to help green FC locking.
We then locked FC servo (wouldn't stay locked for long, but was able to move FC1, FC2 and ZM2 PSAMS to maximize the maximum locked values. Got to 58 on PD FC_TRANS_C for 4.8V or 4.9V. Leaving at 4.85V. Could further increase to 66 on PD FC_TRANS_C iteratively with FC1 and FC2, see attached. Locked for ~20 s max.
To get light (100e-6) on SQZT7 OPO_IR PD, we needed to move ZM3 +100urad in PIT on the sliders.
I then thought that we could go to the location we have SQZT7 IR light and light on the HAM7 WFS and movve ZM3 towards the place where we have known FC flashes and bring back the alignment on the HAM7WFS with ZM2 and FC1. I did this but it maybe unsurprisingly didn't;t work. In hindsight maybe I could have used a different combination of mirrors.
To get light (100e-6) on SQZT7 OPO_IR PD, still needed to move ZM3 +100urad in PIT on the sliders. At which point there is no flashes on FCES green or IR. to get max light on the SQZT7 PD (0.0018) I had to change ZM3 from P,Y (-474, -367) for FC flashes to (-334, -309) for SQZT7 light OR move ZM2 from P,Y (429,132) for FC flashes to (-747,1) for SQZT7 light and centered WFs (not inc. WFS A PIT). In going from SQZT7 light to towards FC light, the beam on HAM7 WFS moves positive in PITCH and positive in YAW. This corresponds to
| From SQZT7 light to FC light | ||
| DOF | PIT | YAW |
| WFS A and B | Positive | Positive |
| ZM1 | Positive sliders | Positive sliders |
| ZM2 | Positive sliders | Negative Sliders |
| ZM3 | Negative Sliders | Negative Sliders |
| FC1 (?) | Positive sliders | Positive sliders |
I changed H1:SQZ-RLF_QPD_A_SEG_3_VOLTS from 1.31087 to 10 to stop this broken WFS A QPD segment from effecting the position on the WFs so much. Didn't make much of a difference though.
Looking at flashes in chamber
When JAC and thus IMC were both locked with 2W, it was possible to see PRMI flashes on a card. It was like a flash per 30 sec or so and it was quite frustrating, but I was able to see that the beam was off-centered into -Y direction significantly.
In the attached, the edge of the card is right in front of the +X-Y edge of the POP red-green dichroic (I'm inserting the card from +Y door). You would think that the beam is clipped but it is not quite, maybe it is clipped a bit on the +X+Y edge of the air-vac splitter downstream, but the transmission of that splitter hits the PM, goes through the lens and toward LSC and LSC POP sensors. It's funny that the centering on the lens looked better than on the dichroic but I might have been tricked by 0 deg AOI VS 45 deg.
See the second attachment for the layout. What I thought was the actual PRMI flash path is drawin in cyan.
