Sheila, Kar Meng, Elenna

Using the new dither lock settings from yesterday, 88686, we were able to see this morning that we were aligning to a higher order mode with two nodes displaced vertically from each other.  We had aligned one of the nodes to reach the IR PD on SQZT7 before the holidays, the other node and the location where you would expect the 00 mode to be were clipping on the way to the PD, which is why we were having a hard time alignnig IR to the OPO using that PD.  With the dither lock on the higher order mode, we adjusted the alignment between the OPO and SFI1 TPF using A:M1 and A:M2 (page 9), so that the mode was roughly centered on our irises and still reaching SQZT7.  

We were able to iteratively improve the alignment of the seed into the OPO by manually finding resonances to set the dither lock to, once we locked to a 10/01 mode we were able to improve the alignment to the IR PD on SQZT7, which then made it easier to improve the seed alignment into the OPO so that we could lock on the 00 mode, realign to the irises using A:M1 and A:M2.  Finally we fine adjusted the seed alignment into the OPO with the cavity scanning.  

Now we can easily dither lock the OPO on the 00 mode, it's quite stable, and with the cleanroom lights off we can easily see this beam on the irises in HAM7 (and SQZT7).  We attempted to align the sqz beam using only A:M1 and A:M2, but these are so degenerate that it seems rather difficult to do.  Betsy loaned us a class B knob small enough to reach the tricky yaw actuator on A:M2, but we still found this difficult.

We decided to set A:M1 and A:M2 so that the seed beam transmitted by the OPO hits our irises after ZM1 and ZM3 and returns through SFI1 toward the B path without clipping, which should set the AOI on SFI1's TFP close to what it was before the cavity swap.  Our plan is to then adjust B:M1 and B:M4 to hit the iris on ZM4 and SQZT7.  For some alignments we are clipping on the aperture attached to A:L2, for others we are clipping on SF2.  We stopped for the day after switching back and forth between these two a couple of times, we have reduced the amount of clipping but still see that we are not well aligned.