This is a summary of the shifts performed on Jul 21 and 22 to install absorbing glasses on the rear part of EQB1 mirrors, in order to block the residual transmitted beams (ghost beams).

The glass support is half-circle designed to be attached on the mirror mount not to affect the alignment and it perfectly fits on Thorlabs-POLARIS-K1S5 (for 1" mirrors) and Thorlabs-POLARIS-K2 (for 2" mirrors) mounts (Figure 1).
The glass is installed inside its mount using a custom 3D printed support that ensures it is tilted by 2.5° around the vertical axis wrt the mirror (Figure 2); the direction of the tilt is chosen in such a way that subsequent residual reflections between the absorbing glass and the mirror, initially at 45 degrees for most cases, are at ever smaller angles, thus ensuring the ghost beam is estinguished on the absorbing glass instead of quickly escaping out of it and towards the metal mount.

Unfortunately, contrary to what we were told not all the mounts on EQB1 are K1S5 and K2: for this reason, we installed all the glasses on the mirrors with K1S5 and K2 mounts, and left aside for the moment the mirrors whose mounts are different.
In particular, the following mirrors are still missing of the absorbing glass:

EQB1_MT2 (2", Low Wavefront Distortion Gimbal Mirror Mount)
DL_M2 (1", Thorlabs-POLARIS-K1-2AH Mirror Mount)
DL_M5 (1", Thorlabs-POLARIS-K1-2AH Mirror Mount)
DL_M6 (1", Newport Clear Edge Mirror Mount)
EQB1_GAOM (1" Thorlabs-POLARIS-K1-2AH Mirror Mount)
EQB1_GM4 (1" Thorlabs-POLARIS-K1-2AH Mirror Mount)

We will design appropriate fixtures to install the absorbing glasses also on these mounts.

During the shift, we noticed the reflected beam from the Green Rotator was ending up on the EQB1 box, so that we temporary blocked it with a beam block (Figure 3).