XPost: alt.lasers   
   From: ceriel@gmail.com   
      
   Hello a.l and s.o,   
      
   I wish to run an experiment to see if the optoacoustic effect in the   
   ultrasonic range will make water mist or fog (10 - 300 µm droplet size   
   size) self-organize. I expect the convert 10.6 µm EM to standing pressure   
   waves in air.   
      
   The resources available to me are those of a small hackerspace, the   
   habits afforded to me from a life-long enthusiasm for science, and a   
   generous helping of patience and sound reason. This should be enough to   
   home-brew a dependable CO2 laser, methinks.   
      
      
   Roughly, the experimental setup would resemble this diagram:   
      
   ]   ~~~  \       ______   
   ]   ~~~   >()==[[______]]   
   ]   ~~~  /   
   A.   B.   C.      D.   
      
      
   A is a thick pane of glass   
   B is a thick mist or fog   
   C is a lens to project the collimated light on the mist   
   D is a CO2 laser   
      
   Water will of course readily absorb 10.6 µm, which is why I have chosen a   
   CO2 laser for this experiment. I expect to generate the fog with an   
   ultrasonic fogger since those are cheap and easy to obtain. The CO2 laser   
   is what I'm really looking for advise on.   
      
   I've read that at the low pressures used for flowing gas lasers the beam   
   persists for around 2 milliseconds, which is much too long for generating   
   ultrasonic sound. Meanwhile the literature on TEA lasers says that the   
   best they could do was 10 pulses per second. Can you kindly give me an   
   expert opinion on why this is so?   
      
   I'm targeting an ambitious pulse frequency of up to 1MHz at enough power   
   to nudge a cubic decimeter of fog around. If successful I will install   
   two beam splitters and mirrors to create a grid in the fog and make a   
   physical equivalent of voxels.   
      
   Given that goal, can I get advice on pulse forming, amplitude and width,   
   for this application? Is this a pulsed DC situation? Can I use AM radio   
   transmitter as a power source instead? Please note that for personal   
   reasons I can only invest money in things like lenses and gas mixtures,   
   but not new power supplies and tubes. Most of the hardware will be   
   scavenged and recycled in hacker spirit.   
      
      
   Thank you for reading, at any rate!   
      
   Sincerely,   
      
   --   
   Nos   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)