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From: ST401385@BROWNVM.BITNET
Newsgroups: net.space
Subject: Re: Phase Conjugate telescope
Message-ID: <8601272039.AA01149@s1-b.arpa>
Date: Mon, 27-Jan-86 15:37:47 EST
Article-I.D.: s1-b.8601272039.AA01149
Posted: Mon Jan 27 15:37:47 1986
Date-Received: Wed, 29-Jan-86 04:17:33 EST
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Reply-To: ST401385%BROWNVM.BITNET@WISCVM.ARPA
Organization: The ARPA Internet
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   >Why won't the phase conjugation technique work in reverse
   >to build a large earth based telescope that removes the effects
   >of atmospheric turbulence  ...  could make the Space Telescope
   >obsolete.

     I've been thinking about this, and I can't think of a good way to
make it work.  There are two problems.  First, as far as I know (but
I'm not an expert by any means) phase conjugation only works on
monochromatic, coherent light (or at least light that is very nearly
so).  More worrisome, though, is the fact that phase conjugation
doesn't remove the distortion.  It antidistorts, so that repeating
the passsage through the atmosphere cancels the distortion.
It sure sounds like there must be a way to use this phenomenon
to cancel out the twinkling of starlight, but it certainly isn't
obvious (at least to me) how.
                             --Geoffrey A. Landis