Sheila, Cheryl, Haocun
We re-centered the WFS A and B this afternoon to fix the misalignment (alog27792). Both of them are centered around (0,0) now and we took measurements on the IMC.
The spectrum (measured at test 1) and transfer function (with 20dB gain) of the IMC were taken both before and after re-centering, but there were nearly no differences between them.
For the spectrum, several peaks are:
-55.5 dBm/Hz @ 197.5kHz
-85 dBm/Hz @ 87.5kHz
-83.7 dBm/Hz @ 25kHz
For the Transfer Function:
UGF @150kHz, and we have a bump close to 0dBm at higher frequency.
IMC loop gain measurements should always go up to 5 MHz. There can be EOM resonances as high as 2.5 MHz which, if unmonitored, can poke up and make another unity gain crossing.