Evan, Keita, Kiwamu, Alexa
It had appeared that the temperature in the LVEA had stablized (alog 15054) so we went about realigning in the IFO. Here is the original alignement we started with:
| PR3 | IM4 | PR2 | |
| Pitch | -246.0 | 13350 | 1057.2 |
| Yaw | 88.0 | -5056 | 2971.3 |
Here are the initial steps we took:
- Align/lock X and Y arm on green. Note: this required a big adjustment since the temperature had also drifted in the end station.
- Adjust PR3 to get COMM beatnote back to nominal of about 0dBm; I adjusted PR3 by +2.5urad in pitch, and +0.3urad in yaw
- Lock the IR to the X arm; this required an adjustment of PR2 in pitch by -34urad.
- Run the wfs feedback to IM4, PR2 to get full build of IR in the x-arm
At this point, we noticed that the WFS had brought IM4 to a bad alignment. Keita has measured the PR2 baffle clearance (alog 15063); and IM4 was not within range in YAW. So we basically started from scratch, and did the following:
- X,Y arm locked on green
- X arm locked on IR
- Run wfs to keep IR build up at a maximum and adjust PR3 until IM4 was at a good position. I had to adjust PR3 by +2.5 urad in pitch, and -76.1 urad in yaw.
- Adjust HAM 3 pico's to get the green beams on ISCT1; i.e. to restore our usual values for ALS-Y, ALS-X_TR_A_LF_OUT ~ 1 cnt each
- Adjust the DIFF and COMM beatnote on ISCT1. Evan had to move the BS in the DIFF path because the X-arm was almost completely off the BS (he will post more about this).
Now we have the following:
| PR3 | IM4 | PR2 | |
| Pitch | -243.5 | 12694.7 | 926.2 |
| Yaw | 13.9 | -5052.5 | 2312.2 |
| ALS X Camera | ALS Y Camera | |
| X pos | 393.1 | 267.8 |
| Y pos | 250 | 289 |
COMM beatnote: 6dBm, DIFF beanote: -1.6dBm. When I get a chance again I will take a snap shot of the ALS camera images, but for reference these image is a bit clipped for both beams; however the transmission is good and the beatnotes are good so it's just the image.
Apparently, the end station temperatures are still drifting. This will affect the DIFF beatnote. Unfortunatly if EX drifts a lot we will need to re-do this input alignment again ...
We this alighment we achieved a build up of around 210 for PRMI after we ran the inital alignment procedure. We are pretty content with this for now. As Evan aloged we couldn't keep going because of an earthquake.
As a reminder, Nic was in the middle of aligning POPAIR on ISCT1 when the earthquake hit, so we need to finish this next time we lock PRMI.
Also, as a note, we have left SR3 in the old configuration and Kiwamu has aligned ASAIR and the camera on ISCT6 for this old configuration.
In regard to the work on ISCT1: I touched up the beat note power onto the COMM diode; it was relatively straightforward. I also did DIFF, but it was much more touchy. Also, the mount for the DIFF interference BS is not oriented correctly; when the beams are passing through the clear aperture of the optic, the TRY beam is clipping on one of the mount knobs. The BS mount needs to be rotated to resolve this.
With PRMI locked, I have gone onto ISCT1 and realigned the beam onto POPAIR_B.