Gabriele, Hang

We took several MICH ASC OLTF at different stages. Please see the attached plot.

First we measured the OLTFs when the MICH was locked using AS_B_45_Q signals (corresponding to GRD states from ENGAGE_DRMI_ASC to DRMI_LOCKED_CHECK_ASC). They correspond to traces REF3 (pink) for P and REF1 (cyan) for Y. The gains were low so we modified the input matrix elements from -50 to -100 to increase the UGF to ~ 1 Hz with 50 deg phase margin.

The red (REF5) and blue (REF4) traces were measured at DHARD_WFS state. At this stage BS was locked using the AS_A_36_Q. The loop gains seem fine there. Although it seemed that in the Y loop there was a feature at 2.2 Hz in both stages (both AS45 and AS36 signal). Its original yet needs to be tracked down.

The measurement template is now in

/ligo/svncommon/IscSVN/iscmodeling/trunk/ALIGOH1/ASC_loops/Measurements/MICH_writeable/MICH_BroadBand.xml

The yaw excitation (channel 3) seems to be good enough to resolve the entire band of interest. For P we used two excitations. Channel 1 (which leads to the attached plot) focuses on the high freq >0.8 Hz part and Channel 0 focused on resolving the features around the main sus resonance.