Sheila, Jenne, Craig, TVo, Hang

We made a MICH alignment servo. It could be used for tasks like measuring the contrast defect in the simple MICH config. A guardian state was created 'ALIGN_IFO/MICH_DARK_ALIGN'.

The script dithers BS at 8.9 (7.2) Hz in PIT (YAW) and demod AS_A_NSUM at the corresponding frequencies. The error signal is then fed back to the BS M1 stage. (We also tried to use the AS45 WFS directly as the error signal, which also worked. The performance was similar to the dither line signal so we just kept the dithering loops).

When creating the servo, we also noticed the the MICH length loop had a strong gain peaking at 12 Hz, so we lowered the gain by a factor of 2 and then the loops worked fine. This gain lowering should now be in the guardian 'ALIGN_IFO/MICH_DARK_LOCKED'.