d350dcc0   
   XPost: sci.physics, sci.optics   
   From: siegman@stanford.edu   
      
   > Hello.   
   >   
   > If anyone wants to investigate acoustic mirrors then have a look at :   
   >   
   > http://www.andrewgrantham.co.uk/soundmirrors/   
      
      
   Nice!!   
      
   I was once shown, some years ago, an "acoustic laser" (maybe at the   
   University of Maryland Baltimore County campus??):  Two large   
   (half-meter diameter) curved metal mirrors (like shallow woks, or the   
   curved metal dishes kids slide down snowbanks on), spaced maybe two   
   meters apart on an optical table to form an acoustic resonator.  In the   
   middle a chunk of "acoustic laser material" consisting of a little   
   match-box sized box with an omnidirectional microphone at each end, with   
   each of these connected through a tiny transistor audio amp to a small   
   speaker on the opposite end.   
      
   Took up a lot of table space -- but "lased" nicely.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)