Rana had asked me to perform another sweep of the OMC to measure the modulation depth.  The results using a single-bounce beam from ITMY are attached; the observed modulation depths are:

Gamma1 (9MHz) = 0.191

Gamma2 (45MHz) = 0.284

This should be compared to the previous measurements from Sep 28th, and also Kiwamu's measurement of the modulation depth and the recycling gain (and subsequent measurements after an RF amp was installed).  There is probably an error of order one percent in these measurements, in particular the 9MHz sideband which is close enough to the carrier peak that it relies on the subtraction of the TEM00 lorentzian.  The results above include this subtraction, but my lorentzian fit isn't perfect, perhaps due to the very slight nonlinearity of the PZT drive.  The plot attached shows the five mode scans that were used to calculate the Gamma's, the peaks identified as the upper and lower sidebands are marked with black crosses.  The measured values for Gamma are consistent (to much better than 1%) between the upper and lower sidebands at each frequency, and from one sweep to the next, so the statistical errors are small.  The raw data are here.

(FWIW the mode-matching from ITMY is still 0.91, consistent with the previous measurement and with the predictions from beam propagation.)

Other OMC work: I connected the OMC shutter controller box above ISCT6, the input for channel 1 comes from the ASC-AS_C SUM output fro the transimpedance board, the controller output goes to the trigger on the OMC PZT driver.  The polarity of the shutter logic seems backwards, 'open' gives 0V and 'closed' is 5V, also I can't get the trigger to fire using the threshold on the PD input.  Probably there is some work to do in Beckhoff-land.