[ATM] Auto Collimation Flat - not cored

[Francis J. O'Reilly]

Shane,

Have you considered the use of a beam splitter for the autocollimator? I would be hesitant to core a perfectly good flat. My concern would be that cutting into the surface of the flat would release stresses in the glass if there are any, and I believe that there usually are even in the most finely annealed glass, and cause a change in the surface. A beam splitter will allow part of the light to be reflected at ninety degrees for your viewing (or photographing) and analysis.

Hope to see you at Stellafane this weekend.

Francis J. O'Reilly