Nic, Jamie, Lisa With the QPD alignment engaged, we did a scan of the OMC in ITMY single bounce configuration. Data are being sent to Koji right now for a careful analysis, but our rough estimate is that indeed the matching to the OMC is around 90%, so slightly better than for ITMX, as expected. Scan data: Sep 9, 2014 21:10:08 - 21:12:00 UTC
Screenshot of the scan data. Koji will post a more complete analysis (a la 13767)
I don't know if Lisa, Nic, and Jamie believe this or not, the mode matching was 0.82 for this scan, which was indeed worse than the result with ITMY.
Note that this mismatch still includes the effect of the misalignment. This scan involved more 1st order mode.
Should we just incorporate the 1st order into the 0th order, qualitatively to saying? In this assumption, both arms are not so different.
Here are the result of the mode decomposition for the Y arm
Here "mode matching" is defined by 1-(CR_TEMnm / CR_TEM00)