From: lwcamp@gmail.com   
      
   On Thursday, February 15, 2018 at 3:04:38 PM UTC-8, Thomas Koenig wrote:   
      
   > This makes your beam bigger to start with, so the area which gets   
   > the energy might also be bigger.  The optimum aperture radius is   
   > sqrt(lambda * D/pi) (with the distance D), the size of the blob is   
   > twice that. So, for 10 km distance and 400 nm, the optimum blob   
   > size would be around 0.07 m, or 70  mm.   
      
   Remember that the beam can be focused to a smaller spot than the primary   
   aperture size.  Taking this into account, it is always preferable to have a   
   larger aperture, in the sense that the focused spot size will always be   
   smaller for a larger aperture,    
   and thus you get a higher intensity on the target.   
   http://panoptesv.com/SciFi/LaserDeathRay/Focus.html   
   http://panoptesv.com/SciFi/LaserDeathRay/Diffraction.html   
      
   Luke   
      
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