Re: [ATM] mirror or lens?

[Michael Peck <mpeck1@ix.netcom.com>]

At 12:40 8/1/05, Mike Lockwood wrote:
>>And one of the family members said, "A mirror is still a 
>>lens."  And he's an astrophysicist, and who really wants to argue 
>>with an astrophysicist?  So I didn't knwo what to say.
>
>I think I would have said that lenses work according on the law of 
>refraction, while mirrors work according the law of reflection.  Let 
>him rebut that.  He can't tell you they're versions of the same 
>phenomena, because they're not.
>

The "law of refraction" and the "law of reflection" are both derived 
from Fermat's principle 
(http://scienceworld.wolfram.com/physics/FermatsPrinciple.html). 
Modern optical design doesn't really distinguish between reflective 
and refractive surfaces in any fundamental way, which is why you can 
use Zemax, OSLO et al. for both.

Astrophysicists may not know much about optics in general, but in 
this case the astrophysicist was correct.

Mike Peck


_________________

Michael Peck
email mpeck1@ix.netcom.com
Wildlife photoblog! http://wildlife-pix.com
Amateur telescope making http://home.earthlink.net/~mlpeck54/astro/astro.html 

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