T. Vo, C. Cahillane, G. Mansell

Summary:
-We have aligned the ITMX and ITMY Hartmann wavefront sensor periscopes to get the ALS-X green beams co-aligned with the SLED beams.

-While we see something on HWSY (attached image), we’re not quite sure yet if we’re sampling the right optical surface (ITMY) or something else, investigation ongoing.

-We don’t currently see a signal on HWSX, alignment ongoing.


Details:

We steered SR3 to get the ALS-Y green beam onto the ITM Hartmann sensor table. This was quite arduous as none of the workstations or CDS laptops were allowing anyone to log in.

We can see green light on both HWSX and HWSY paths, assumedly the Y path is from the reflection off the back surface of the beamsplitter.

We had to adjust the positions of both periscopes on the table to centre the green beam on the top mirror in yaw (Y periscope moved by ~1 inch, X periscope by a bit less), and adjust the position of the top mirrors to centre the beam in yaw. We then steered the top and bottom periscope mirrors to align the beam with the SLED irises set up by TVo previously.

We encountered an interesting phenomenon where one of the steering mirrors on the HWSX path (between the two irises) seemed to be angled right at Brewster’s angle for the green beam. Alignment onto the second iris was virtually impossible as there was no reflection off this mirror. We instead placed a new iris aligned to the SLED and aligned the green beam to this.

Once we have a CDS computer working on the floor we'll be able to take the Hartmann sensor plate off HWSY and confirm which optical surface we're sampling, as the baffle apertures should be visible if we are hitting ITMY.