In the past two days we’ve tried to realign the ITMY Hartmann Sensor. To do this, we followed the standard procedure:

 

1. Align the SLED IR beam to the center of all the optics on the table up until the bottom periscope mirror.

2. Insert two irises and center them on the IR beam.

3. Lock the ALS green beams on the arms

4. Adjust the upper and lower mirror on the periscope so that the green beam leaking from the vacuum system is aligned to the center of both irises.

5. Note the position of the green beam on the two HWS position sensors using the normalized coordinates.

H1:TCS-ITMY_HWS_POSITIONSENSOR1XNORM, etc [These channels were added at LHO on Tuesday].

6. Turn the HWS camera on, log into the HWS machine and stream an image from the Hartmann camera to confirm the return beam is incident on the camera.

7. adjust the last mirror before the Hartmann sensor to center the beam on the camera.

 

Normally, we would tweak the alignment by removing the Hartmann plate and centering the SLED beam intensity distribution within the shadow of the beam-splitter baffle. That isn’t an option with the current installation of the ITMY HWS as the system has the wrong magnification (4x instead of 17.5x) due to the wrong in-vacuum lens being installed.

 

We got a strong return beam and confirmed the intensity changed as we pitched ITMY. However, long story short, we had managed to align to the reflection from the AR surface of ITMY (and, in doing so, had also picked up a reflection from the AR surface of the CP).

 

I have an algorithm for finding the main return beam from a coarse green alignment. I will try to code this into Guardian over the next week.

 

Currently, the ITMY Hartmann sensor is turned off.