Terry, TVo, Dan Brown

Today we tried to align the squeezer seed and PSL beams to the OMC to do some mode matching tests. The seed beam was far too weak to achieve anything in the end though.

Initially we aligned the squeezer beam to AS A, AS B, and the OMC QPDs by steering the beam with ZM1 and ZM2. This required some significant adjustments to the slider values, old and new values in picture attached. The sum on AS A and B maxed out about 8 counts. With the seed beam diverted we then aligned the IMC and did a single bounce from ITMX with the AS alignment loops closed. We then switched off the loops and unlocked the IMC, letting the integrators keep the alignment fixed towards the OMC.

We then realigned the seed using ZM1 and ZM2 again to center on all the QPDs for a SRM single bounce - the seed beam should be roughly aligned with the single bounce beam from ITMX now. However, when misaligning SRM and doing an ITMX single bounce the seed beam was no where to be seen. With SRM and ITMX aligned we could see misalignment fringes drifting over the seed beam on AS air camera, so the alignment couldn't of been that far off. We tried to align ITMX and SRM better to remove any misalignment fringes for the PSL beam and redid the zeroing of the see alignment on the QPDs, but we still couldn't see anything. No sign of the ITMX single bounce seed beam when doing an OMC can either.

Given we saw 8 counts with SRM single bounce we would expect to see about 0.25 counts off of the ITMX. We probably need an order of magnitude more seed power to see much. Terry seems cautiously optimistic we could achieve this, he thinks we have about 100uW of seed coming out of the OPO currently.

We also wanted to try and see how the astigmatism of the SRM single bounce beam depended on alignment. However the OMC scans weren't clean enough to resolve the astigmatic 2nd order peak due to being in air, so that will have to wait.

The ZM1 change has also shifted the beam on the SQZT6 camera position when closing the beam diverter.

We left the PSL shutter closed and turned the purge air back up in HAM6.