ALSX alignment trouble:

In the morning, we've found that the X arm was not flashing and we couldn't see anything other than the straight shot beam from TMSX on the camera. There was no reason to suspect that TMXS and ITMX were bad but baffle allignment were performed for those.

We then restored ETMX to the last time ALS-X was locked based on oplev but still no sign of anything other than the straight shot on the camera. In retrospect this could have been because there was a 1.5F temperature change in the end stations. ETMX baffle script was used but there was no  way it could have worked because the slider/TEST calibration is totally wrong now, presumably due to rubbing. The script found nothing.

I eventually decided to manually do baffle alignment i.e. start from the in-lock position of ETMX based on the oplev, manually steer ETMX such that the oplev changes by (10.2, -8.4) urad to see ITMX baffle PD4, maximize that PD, record the oplev position, then move to PD1, again manually, record the oplev position, and finally put ETMX manually to the average of two oplev positions. I saw the return beam from ETMX immediately and we were able to lock ALSX.

ALSY didn't have any problem so I left Y arm alone, and aligned BS using the AS camera while arms were still locked with green. Both green beams were where they have been in the ALSX and ALSY camera.

Probing HAM1 alignment and HAM3 pico:

We misaligned ITMY and ETMY and increased H1:IMC-PWR_IN_OUT16 to 60W. X arm was still aligned.

We used this configuration as an OK substitute for single bounce, because I didn't want to misalign ETMX. If ETMX were misaligned, we knew that it won't go back to the same position after aligning it again (because it's stuck somewhere and there's always a sudden big motion after making a big alignment change). Then it will take a long time to align the X arm again.

I first probed the HAM2 alignment using just PR3 without using PR2_SPOTMOVE by looking at POP_X_SUM while POP_X centering was enabled.  I was interested to see if the situation is the same as reported in alog 91725 (i.e. the POP IR beam is likely clipped at the bottom of something, presumably the top or the bottom periscope mirror in HAM1).

PR3_M1_OPTICALIGN start position was [-142.7, -236.7].

The beam was not clipped in PIT at the bottom today, maybe due to pico-ing efforts in the past days both in YAW and PIT or something else, but POP_X_SUM still decreased significantly when I moved PR3 by negative 2 urad in PIT (PR3_M1_OPTICALIGN_P_OFFSET = -144.7).  This means that there was a hard edge about 2.7mm (plus about a radius of the beam, or ~2.5mm at the peri in HAM1) from the center of the beam according to the the right panel of the plot attached to alog 91725. This was too close.

I moved PR3 to -140.7, i.e. the edge is ~2*2.7mm+2.5mm ~  7.9mm from the bottom of the beam. This is three times the beam radius and hopefully OK. I didn't go further because I thought that POP_X started decreasing, but looking at the trend it seems like I was worried about less than 1% change so I could have moved more.

The hard edge was also seen in YAW, qualitatively compatible with Louis' observation in alog 91702, when PR3_M1_OPTICALIGN_Y_OFFSET was changed by positive 4 urad in YAW (~5.5mm in -Y direction on the periscope mirror). This was comparable with PIT situation after my adjustment. Also, in the past, when Sheila moved the beam away from the hard edge (though her intent was not that) the ALSY beam was eventually lost. Based on these, we decided to leave YAW alone.

At this point PR3_M1_OPTICALIGN position was therefore [-140.7, -236.7]. Just to make sure that ALSY beam wasn't lost, I  locked ALSY again and it was still there on the camera in ISCT1. 

I took the screen shot of the ALSX camera and put the PR3 slider back to the starting position of [-142.7, -236.7]. Of course both the ALSX and ALSY camera image moved.

I then moved HAM3 pico only in PIT to move the beam up in HAM1 so the camera image matches the screen shot I just made.

H1:SYS-MOTION_C_PICO_A_CURRENT_Y_POSITION  changed from -1467 to -1312. H1:SYS-MOTION_C_PICO_A_CURRENT_X_POSITION stayed at 1125.

ISCT1 realignment:

Louis and Sheila went to ISCT1 and realigned things. 

ETMX and TMSX have been drifting in the past hours:

ALSX sees that. In the past 3 hours, ETMX drifted by 5 urad in YAW according to oplev, TMSX by 2urad in PIT, and ASLX alignment is bad as of now.