Stefan B, Jennie W, Sheila

Summary: Checked OMC step responses and they converge in 30s or less without saturating suspensions. These loops can be slowed down if need be.

Since locking yesterday there has been no light through the OMC.

Sheila decreased the OMC QPD whitening gain as the QPDs were saturating. This was turned up during the vent so she changed it back to what it was in O4a.

We still had some sort of signal into the OMC QPDs. We turned off the pitch and yaw offsets to these QPDs and then went into the whitening filters and turned off the bottom row of gain filters so only the low pass filters are on and set the offsets to be the negative of OUTMON. First image is original filters for QPD B and second is the filter once setting the offsets (QPD A was done in the same way).

We did this dark offset procedure for QPD A and B on OMC and then Stefan manually set the offsets on DCPD A and B to 0.03 on input to filters.

Sheila did the step responses for the OMC ASC loops by switching on offsets in the POS X, Y and ANG X, Y filters in turn.

POX X offset causes POS X and ANG X to move, POS X converges in 30s and ANG X converges in less than 5s. This means we could decrease the gain in ANG X loop. See image 3.

POS Y offset coupled to both POS Y and ANG Y (half as much) and they both converge in 30s.

ANG Y offset does not couple to other DOFs and converges in 20s.

ANG X offset also does not couple in to other DOFs and converges in 20s.

First image shows POS X and ANG X offsets being inplemented and second shows POS Y and ANG Y.