K. Tanaka, Nakano, Akutsu on 12th Feb.: continued from 15986.
Abstract
Without resonance of IMC (the beam to MCe was shut), S-pol beam 0.7~3W (measured at MCI_REFL with the Ophir power meter there) could pass through MCi and MCo with so enough intensity that I could see it with a sensor card. This means we may be able to adjust/align POM1 with the S-pol without resonating the S-beam in IMC.
Detail
First, with P-pol input beam from PSL (using the setup left on10th Feb.), we checked where the main beam and the ghost beam from MCo pass thourgh the viewport windows on the large gate valve between MCF and IFI. The main beam hit on the window at a couple of cm displaced point in yaw in +Y direction (Figs. 1 and 2), which may be as designed. Need to confirm later. As already reported in 15986, the MCo ghost beam hit at the -Y edge of the viewport (Figs. 3 and 4).
Then, with S-pol input beam from PSL, we confirmed the main beam through MCo had so sufficient power that I could see it with a sensor card, although it was faint. For now it is difficult to say what is the power preciely (need calibration later!), but the Ophir power meter on the MCI_REFL optical table showed 0.7-1W (there were fluctuations in the read); the beam spot was further clearer when we use about 3W. In my rough check, the beam was clipped anywhere before IMMT1, so it must be better to align the optical path from STM1 carefully. Note that we did not align the optical path after the re-alignement of the PSL-IMC optical path reported in 15830. Although it was clipped, I confirmed the beam was flying toward the PRM chamber. I could not check the reflected beam from PRM, but anyway, re-alignment from STM1 must be thee first thing to do before everything. What is difficult is scheduling strategy; POM1 can be aligned after we align the beam to the level it can come back from PRM, on the other hand the MCF chamber must be closed as early as possible so that we can do the commissioning work (including WFS). Everything might happen almost the same timing...??
Memo
An encoder for HWP in PSL room; whether it was ordered or not?
