Nice recovery of the lock!
Do you think the spot distance at PR2 makes sense if we consider the dispersion?
We removed the extra DB25 cable (with cut wire isolating pin 5 [Attachment 1]), restoring the original PRM UL/UR/LL connections ---> UL counts ~650
It may have been that the foil caps were causing pins 1 and 5 to short in the first place, so removing the caps and restoring the original cable fixed the issue. Final state in Attachment 2.
Since BHD optics had been removed from the ITMY chamber, the leveling of that table is off. ITMY is no longer aligned, so YARM is no longer a good reference for aligning the AS beam. So I misaligned YARM and used XARM alignment (T=0.9) to set the AS path.
Next I noticed that AS1 isn't properly damping - the damping loops would were driving pitch motion and tripping the optic [Attachment 1 - damping loops were swithced on at the start of the traces]. This was likely a result of uneven table leveling, causing extra pitch/yaw coupling. The AS beam was misaligned on the camera (too high) and shaking significantly.
We opened up the BS chamber and I spotted the lens along the AS path. Looking at it with the IR viewer, there was a bright spot hitting very low on the optic [Attachment 2]. I tried to trace the AS path downstream from SR2, but got confused by several beam spots between the BS and ITMY chambers.
Since the misleveling of the ITMY chamber has misaligned AS1 (and caused issues with AS1 damping), it is hard to diagnose AS beam alignment. I spoke to Paco and we think it would be better to wait until the BHD platform is installed and the ITMY table is level before we diagnose any further.
[Yuta, Paco, Radhika]
First I located the existing .db file for lab temperature monitoring: /cvs/cds/caltech/target/c1pem1/tempsensor/C1PEMaux.db.
I added the following CALC channels:
Here is the example for XEND temp:
*Note that the SCAN field was required for the channels to update. The SCAN field was added to the original (degC) channel entries as well.
Next, C1PEMaux_modbusIOC.service was restarted (running on c1susaux). At this point the new degF channels were accessible via caget.
To add the new channels to fb, we followed Koji's instructions here - added the new channel names to C0EDCU.ini; restarted fb; restarted rts-edc_c1sus.
We could pull up the new channels on ndscope [Attachment 1].
Attachments 1,2 show the starting state of the ITMY table weights. The e-bubble reading was different from close-out after removing the BHD optics, and fluctuating more than before:
(x,y) = (-0.00, +0.20) ± 0.01
(x,y) = (-0.02, +0.19)
Our goal: (x,y) = (+0.03, +0.17). So regardless of the fluctuation, weight needed to be shifted to the right and forward (from standing at chamber door).
(x,y) = (+0.03, +0.17)
The final state of the weights is in Attachment 3,4. The final e-bubble reading was back to (x,y) = (+0.03, +0.17) ± 0.01.
(x,y) = (+0.03, +0.17) ± 0.01.
After this, AS1 was able to damp [Attachment 5].
Open BS chamber and confirm AS beam alignment.
- Turn off the MC autolocker. Relock the MC with only the acquisition settings; no boosts
and no RGs. This makes it re-acquire fast. Turn the MC-WFS gain down to 0.001 so that
it keeps it slowly aligned but does not drift off when you lose lock.
- Use low-ish gain on the FSS. 10 dB lower than nominal is fine.
- Setup the o'scope (100 MHz BW or greater) to do single shot trigger on the MC2 trans.
- Flip FSS sign.
- Quickly flip sign back and waggle common gain to get FSS to stop oscillating. MC
should relock in seconds.