CD's as parabolic mirrors?

From: <(>
Date: Fri Dec 8 11:33:10 2000

For years I've used them to reflect light inside a machine to read legends
on cards and such.

I've got flashlights, but theres never one when you need it...



In <>, on 12/08/00
   at 12:33 PM, John Tinker <> said:

>I just noticed that sunlight reflecting off the top side of a CD focuses
>somewhat, maybe with a focal length of about 20 feet. Off of the data
>side, it spreads. I've tried it with several different types, and so far
>they all show the same effect. Would anyone care to explain why?

Jeffrey S. Worley
Complete Computer Services, Inc.
30 Greenwood Rd.
Asheville, NC 28803
Visit our website at HTTP://
Received on Fri Dec 08 2000 - 11:33:10 GMT

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