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RE: Second Surface Mirror softening

  • From: P3D Norm Goldblatt <normgold@xxxxxxxxxx>
  • Subject: RE: Second Surface Mirror softening
  • Date: Tue, 30 Sep 1997 20:11:24 -0800
Why would second surface mirror soften image? Maybe it is due to the
second reflection off front surface.  If the object is far away, these
two images would be superimposed, but only if plate was very parallel. 
When the image is close, there would be some astigmatism which is
introduced whenever a thick plate is in a converging beam of light. The
effective thickness is twice the actual thickness of the mirror and then
some, for the slant distance thru mirror (45 degres- add a factor
1/sqrt2. 

Of course, it could just be due to the poor flatness of the plastic
mirror! But that's not as much fun talking about!

Norm
http://www.aimnet.com/~normgold


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