XPost: alt.lasers   
   From: ceriel@gmail.com   
      
   On Wed, 23 Apr 2014 13:44:51 +0000, nanicoar waxed lyrical:   
      
   > 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,   
      
      
   My answer appears to be a gallium arsenide optical modulator!   
      
      
   --   
   Nos   
      
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