After I aligned the IR interferometer (no ASS - we still need to figure out what's going on with that), I am trying to find the green beatnotes for each arm.
First, I locked the green lasers to each arm.
I then went out to the PSL table and aligned the Green Yarm path by overlapping the near-field and far-field of the yarm transmission and the PSL green pickoff. I then turned on the power for the Beat PDs, since it was off (I confirmed that the outputs were plugged into the beatbox, so they are seeing 50 ohms). I assume that the beat PDs were off since Manasa pulled the Beatbox last week, but there is no elog reference!! Anyhow, after seeing a real signal, I maximized the DC power on the beat PD for the Yarm. I then maximized the light on the DC transmission PD for the Yarm.
I looked at the Xarm, and the near-field alignment looks okay, but I haven't checked the far-field.
I started looking for the beatnotes from the control room:
I am changing the SLOW_SERVO2_OFFSETs by 30 counts, and then unlocking and relocking the arms, and checking to see if I see a peak on the RF spectrum analyser.
The Y offset started at -10320, and I found a beatnote at -11230 (beatnote is about 26MHz). The X offset started at 4500. Going larger seemed to get me to a less bright TEM00 mode, so I switched and have been searching by going down in offset, but haven't yet found the beatnote. I suspect that I actually need to align the X path on the PSL table. The Y beatnote is very small, about -30dBm, so I also need to tweak the alignment by maximizing the peak value.