JimW, NikoL, JimW, ArijitS, RickS

This morning, we went into X-end to try to restore the alignment of the Pcal beams.

First, we tried tapping on the Pcal periscope flexures with the newly-acquired aluminum hammers.  That was not as successful as we had hoped.  The beams didn't move as we expected, which probably means that the tapping was not moving the periscope the same way it had shifted during the addition of the vibration absorbers and the "baffles and shields" hardware.

In the end, we used the adjustable mirror mounts on the periscope to restore pointing to the ETM target mounted on the suspension frame.

We also adjusted the centering on the 4th lower beam periscope mirror (M4)r.  We name the lower beam relay mirrors M1-M5 starting at the Tx module.  We adjusted M2 pitch to bring the beam up on M3, then adjusted the pitch of M3 to lower the beam on M4.  With a couple of iterations, we significantly improved the centering of the lower beam on M4.

We then adjusted the relay mirrors in the Receiver Module to center the beams on the aperture of the Rx integrating sphere.

We also adjusted the compression of the upper periscope flexures.  As found, the upper gaps were slightly more that 0.230".  We adjusted the flexure compression screws to reduce the gaps to slightly less than 0.210", increasing the pre-load forces constraining the periscope structure.

Photos of the beam positions on the ETM target and at the entrance to the Rx module integrating sphere are attached.