Elenna, Keita, Ryan Short, Oli
We were able to lock the Michelson. We started with a beam reflected off ITMY on the AS camera, aligned SR2 to center that on AS_C. Then we rastered ITMX at 0.06Hz and 0.07 Hz in pitch and yaw, until we saw the beam flash by on the AS camera. Screenshot of the sliders that gave us an aligned michelson attached.
We ran prep_for_locking, which changed the BS BIO state, but we have changed the guardian weights to not do SDF revert for now.
We had to reduced the gain used for the michelson, it would normally acquire with a gain of 4000 and set it up to 8000 when locked. To match the michelson UGF in our template, we had to reduce the gain to 1200, so there is a factor of 6.7 more gain somewhere. The MICH IN1 error signal amplitude is 6 counts now, Elenna found a time in O4 when we were doing inital alignment and the amplitude was 8 counts, so the optical gain is similar.
With the dark michelson locked, Elenna manually aliged the beam splitter, sliders attached after fine adjustment.
We did not see any flashes in the POP air path. We saw PRMI flashes on LSC POP LF of up to 2 or 3 counts with 10 W input power. Looking back at a time when PRMI was trying to acquire with 2W input, there were 100s counts on POP A LF. Keita and I tried moving PM1 to increase these flashes, but we were not able to increase them.
Our plan is to continue tomorow to move PR3, following with the other optics (PR2 spot move), to see if we can increase the flashes on in vacuum POP this way.
After we locked Michelson, we were not able to find a PRX fringe on AS AIR when aligning PRM. We tried swinging PRM around a huge amount, but had no luck.
Keita and Sheila went to ISCT1 with PRM aligned, and aligned the REFLAIR beam to the ISCT1 REFL camera. Then, we misaligned PRM and tried to find the Michelson fringe on the same camera.
By swinging PR3 around, we were eventually able to see the Michelson at ISCT1. Keita set the PR3 slider to bring the beam on the camera, however this lost us the beam at AS.
To maintain the alignment of PR3, I walked PR3 back to its original alignment while moving PR2 to keep the beam on the refl camera.
Then, we swung SR2 around to find the beam at AS. We found the beam, and got it back on the AS AIR camera enough to run SR2 ALIGN in the guardian. I offloaded this alignment and then ran teh AS centering loops, also offloaded. This means we have MICH fringes on two cameras.
We can now see PRX on the AS AIR camera. I did some touch up of the PRM alignment. Keita and Sheila are now working on the POP path.
The first screenshot shows the alignment sliders after we walked PR2 and PR3, the second is after we were able to have the beam on both ISCT1 REFL and AS AIR.
