The IMC REFL beam on the bottom periscope mirror was found to be low and off in yaw, which meant there was clipping and scatter on the high power beam dump path, and required an additional beam dump for a set of second reflection beams, and an iris in the path to the REFL camera to eliminate extra beams.

The REFL beam path has been aligned at the periscope, and restored through the rest of the path (with some help from Jenne, alog 46042, who centered the IMC WFS in pitch and yaw with the picos, after Jason and I centered for total power).

To get the best elimination of extra beams, the pick off mirror, IO_MCR_M14, was moved further upstream from IO_MCR_BS1, that sends a beam to the REFL DC diode, and a razor blade beam dump was installed behind the optic.

The beam dump, IO_MCR_BD5, was adjusted to block as much of the second reflection from IO_MCR_AR1 as possible without clipping the main beam, but the main beam and the AR1 second reflection separation is minimal, and smaller than my experience of the past.   The behavior of the junk light present at BS1 was unexpected, so it's not clear if the two expected beams, or the two plus an additional beam, are present, but regardless, it was not possible to fully dump the junk light without clipping the main beam.

Snapshots of IMC REFL and IMC Trans attached: REFL unlocked, REFL locked, TRANS locked

- Jason, Cheryl