R. Takahashi, Akutsu; following 22934
Summary
Completed finalization of invac components in the OMC chamber.
Details
As the same as yesterday, I made checking if OMMT2T is healthy and if OMC ASC loop can be closed before starting the work. Today's works were donw with IR-X locked. Basing on the reference drawing Fig. 1,
- Steering mirror 3: re-tweaked. This steering mirror is to do steering OMC_REFL, and yesterday we aligned this mirror so that OMC_REFL would illuminate about the center of the relevant periscope upper mirror. But today, I changed my mind when I could find only one ghost beam due to OMC_REFL from the viewport window; the number must be two in theory and experience. This would suggest that the other ghost beam was just scattered somewhere, and in fact it was at the edge of the viewport flange. So we tweaked this steering mirror 3 so that this ghost beam could peacefully launch away without being scattered (to be dumped with Beam dump 4 in the end); see Fig. 2. As a drawback of this tweaking, unfortunately, OMC_REFL is not anymore illuminating the mirror in the periscope outside the chamber, and rather the pillar itself (Fig. 3). Anyway, I left this beam undumped today. Please relocate the periscope when needed. Note that the neighboring beam is AS_RF, which is essential for locking FPMI in RF, so if you relocate the OMC_REFL periscope, do not clip RF_AS.
- Beam dump 4: reinstalled. As described above, this catches the ghost beams created at the high-quality viewport window from OMC_REFL.
- Beam dump 15: additionally installed. This catches ghost beams born at the high-quality viewport window from RF_AS.
- Beam dump 5: reinstalled. This is to catch one of the OMC transmission ghost beams (Fig. 4). As the OMC can't lock in air, what I could do was only keep looking here and wait for instanteneous flashing. In fact I could observe the ghost beam flash, so I determined to install this beam dump.
The other beam dumps and steering mirrors in Fig. 1 are kept unchanged as in 22934, meaning I determined not to install Beam dump 6, 7, 8, 12, and 14 at this time.
