Re: [ATM] collimation

[johncdeitz@comcast.net]

Hello John: You need to stop thinking in terms of a beam. This is NOT a collimated beam but a POINT source at the surface of the mirror (Huygens). This is much like knife edge setup but with the images on top of one another (as if your source where your eye). IF the setup were with a laser THEN one would have to send the beam right down the center of the tube! But this is NOT the case here.
John
-------------- Forwarded Message: --------------
From: Joseph Johnston <usc@sover.net>
To: johncdeitz@comcast.net
Subject: Re: collimation
Date: Tue, 9 May 2006 20:24:05 +0000
> Hey John
> 
> Thanks for the reply.
> I figured I had the drawing correct from your description. BUT you
> STILL didn't answer ANY of my questions. They were;
> 
> "how do you propose to accurately send the beam through the glass 
> perpendicular to the surface of the curvature of the glass exactly where
> the beam comes through? Or have I missed something critical in your
> plan? If I have not missed anything, 1/10 of one degree off from
> beam alignment could possibly be a huge error. Correct?"
>   
> 
> johncdeitz@comcast.net wrote:
> 
> >Hello Joe: Your illustration hits the mark. Ignore the diagonal for now. The 
> light originates as a "point" at the surface of the mirror and is reflected from 
> the autocollimation surface back to the mirror. What is this distance? It is the 
> radius of curvature of the primary! Sound familiar? When you look through the 
> peephole you see multiple images of the spot with less than perfect collimation. 
> The images can be followed to bring them into perfect alignment when the eye is 
> flooded with red light with perfect alignment. I have used this process with a 
> video camera. Illustrations can be seen: www.bma2.org , search CONSTELLATION, 
> April 2000, collimation.
> >John
> >
> 


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