I put a camera on the HAM2 West door, which looks at CW1, the back side of the wedge, which is carefully aligned to shoot through the IM1 tower.
This week I developed a procedure to use PRM with a single bounce, to move the REFL beam on CW1, and and look for clipping. The procedure revealed that when PRM is in it's aligned position plus an additional 200urad in yaw, there's an increase in light on the baffle, consistent with the REFL beam starting to clip. With PRM at -1000urad, the REFL beam is clearly seen on CW1 to thr right of the main input beam.
Using the image and a beam path simulation I wrote in matlab, I've measured the main input beam to be between 2mm and 3mm from center.
I need to adjust my HAM2 top camera to improve the view of the IO Faraday output side, which is planned for next Tuesday, in order to realign through the Faraday, to correct the mis-centering at both the input and output Calcite Wedges.
compared to the main input beam, which I've used to identify the location of the main input beam on the wedge. A diagram and images attached.
I've written up how I measured beam positions using images. My measurements from the image are consistently about 20% larger than the beam path simulation. Given the uncertainties in both methods, and and uncertainties in the beam path, I'm not concerned about the 20% difference.
Both measuring methods identify the main input beam as 2+ mm from the center of CW1, which will effect the IO Faraday performance.
I've recalculated the centering of the main beam on CW1, after Keita identified my original calculation as low by about 10%.
My updated calculation shows the main beam as +2.2mm from the center of CW1, where I had originally posted +1.9mm.
The measured value from the image is +2.4mm, so the updated value of +2.2mm is now within 10% of the measured value.
Attachment is updated to show the change.