Morning report.
Pictured the beam position on the input and the output side plate of the EOM.
We'll see if it's off or not, doesn't look bad but we'll see once I have time to look at the pictures.
We realigned the beam into IMC, mode mismatch < 0.4%.
I just assumed that the MC alignment itself was good. I found MC2 in misaligned state and changed it to aligned.
We had to work both on PIT and YAW, but mostly in PIT (i.e. the difference in horizontal beam deflection between the old batch crystal that we're using and the new batch crystal is smaller than the difference in vertical deflection).
Good news is that the mode matching is still pretty good. Attached is the MC2 trans VS time while the PSL frequency was ramped. Assuming that the tiny thing pointed by the green arrow is actually 2nd order HOM peak, the mismatch is 0.036/9.4~0.4%. Consider this as an upper limit, because it's hard to tell if the "peak" is actually a peak, could be noise fluctuation.
Afternoon:
Tony and Jason worked on REFL path: alog 89154.
Elenna confirmed that the demod phase for IMC didn't change: alog 89149.
We'll have to move the EOM again.
Looking at the pictures shot this morning, the beam seemed to be a bit too much in -Y direction relative to the EOM aperture especially on the output plate.
Assuming that the wedge angle is the same (2.85 degrees per surface) and the deflection angle is the same (2.35 degrees per surface) as the new batch, the EOM should move at the input by about 0.7mm and at the output by about 1mm, both in -Y direction.
We'll move the entire structure by marking the +Y edge of the EOM pivot base plate using two dog clamps and then inserting washers between the dog clamps and the base.
I measured the edge thickness of four big slotted washers, they're not uniform in thickness (they're not machined after all) but they're all between 24 and 29 thou (between 0.61 and 0.74mm). Inserting one big slotted washer per dog clamp might be good enough.
