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    Re: Sight reduction formulae/mirror quality
    From: Randall Morrow
    Date: 2011 Dec 1, 14:10 -0800

    Alan, you wrote:

      "In any case, re the mirror that you used, did you happen to get "optically flat mirror glass", or did you just get lucky with an ordinary piece of mirror glass. I believe the mirror you used is considerably larger than the one I have."

       I purchased a first surface mirror from Alpine Glass, and they cut it to my 6 x 6 inch size request.   The charge was $16.00 plus shipping.   This size was cut by them from a 12 x 16 sheet that normally sells for $65.95.  (item # 25KFSM) (I guess 4 people could buy a whole sheet and cut it into 4 6 x 6 pieces.) The mirror is very clear and flat from edge to edge with no distortion at all, but it did not specify "optically flat".   They sell these mirrors for craft projects like kaleidoscopes.  Their web site is http://www.alpineglass.com    The web site shows the full sheet price and it took e-mail contact to arrange to get a fraction of a sheet cut to size.   The service was excellent and delivery fast.  

    Randall F Morrow PT
    Ergonomics Safety Consultant
    Chronic Pain Program
    Kaiser Permanente - Kern County - Bakersfield

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