N. Satō, Akutsu

Summary

Confirmed we can implement OMMT2 transmission optical path.

Details

We eager to have a reliable reference for alignment of the output optics, especially SR2 and OMMT1, and beam centering on OMMT1 and OMMT2. As monitoring OMMT2 trans (or OMMT2T) would tell us some of them, we would like to have OMMT2T, which has not been planned before. On that, we have several concern:

1. Is this transmission beam viewable? OMMT2 transmissivity is very low. -> the beam spot could be found with a sensor card, although the brightness was very faint (Fig. 1); you might need mighty eyeballs (shin-gan).
2. Does a solution exisit to extract the laser beam out of the chamber? -> Yes, we can extract the beam (Fig. 2) with a steering mirror (to be called OMMT2T-STM), although using a tentative steering mirror, which had been used for IMMT2 trans extraction during O3GK. Note that for O4 we gave up to extract IMMT2 trans and the correspoding beams were dumped, so the steering mirrors, and more importantly, their supporting structures had not been used.
3. Can a pylon be located there? -> Yes (Fig. 3).

To do these, we firstly detached the beam sheild on the behind of the OMMT2 suspension structure.