First tried working with only ETMy & TMSy, but had no luck gettting flashes above 0.72.
Decided to try an Initial Alignment, but this means Y-arm needs to atleast lock. So unlocked and tried the new knob, ITMy, but still ZERO luck. It's having a hard time just grabbing a 0:0 mode. Have tried tweaking ITMy, ETMy, TMSy with no luck. Do not see any issues on the ALS overview. The polarization is at 2, but maybe I can mess with that. I'm desperate at this point.
Still no improvements for the Y-Arm. Symptoms:
Ideas Tried So Far:
1) Took ITMy, ETMy & TMSy sliders to time before last lock: 1:41utc. NO CHANGE.
2) As an act of desperation, I lowered the polarization from 3 down to 0 for the yarm (and while at it for the xarm from 23 down to 17). NO CHANGE.
3) I'm going to have lunch now.
Ideas to try next:
After this, I will have to leave for the DAY team.
NOTE: This is my first time locking after the Camera Bump. So not sure I'm missing a new trick for locking. Will read through alogs if I think there's any hope.
11:09 Going to CORRECTIVE MAINTENANCE (down since 9:08utc)
Since this isn't the usual locking or aligning, I'm going to mark this down time as CORRECTIVE MAINTENANCE since something is wrong and beyond my normal means.
The algnment of the y-arm was really bad. The strongest mode was a TEM01 mode at 0.7 transmission! The Y-arm locking condition triggers on transmitted power only with a threshold of 0.6. This means the auto-alignment loops were turning on which will result in nothing good when locked on the wrong mode. I also noticed that the y-arm will lock on many bad modes all the times and I lowered the acquire gain from -4 to -20dB.
One thing to be careful when doing the alignment with a free swinging test mass is to make sure that the TEM00 mode gets optimized. The only way to tell is to look at the camera. This is hard while free swinging, since the y-arm experiences a large number of higher order modes. Also be aware there is a delay between the camera image and dataviewer/ndscope.