6f8db594   
   From: hwabnig@   
      
   On Sun, 19 Dec 2010 16:28:25 -0800 (PST), Martin Devera    
   wrote:   
      
   >Hello,   
   >   
   >i'd like to understand interference which I see and can't find its   
   >cause. Maybe someone can hint   
   >just after looking at the image: http://bn.eax.cz/interf2.jpg   
   >It is bare 5mW 650nm LD (without glass window), and spherical meniscus   
   >lens d=70mm, f=170mm.   
   >The image is at distance of 32m, its diameter is 100mm.   
   >   
   >The image is stable and contrast with minor screen perturbations but   
   >with screen 2m or less before   
   >lens there is no pattern (its contrast goes low as I approach lens).   
   >I tested with other lens and LDs and can see similar patterns.   
   >   
   >Apperture 70mm seems too big to produce such big diffraction, maybe   
   >kind of abberated   
   >wavefront interference like in pg 705 of Siegman's Lasers ?   
   >   
   >thanks, Martin   
      
   That's the typical muster of a pinhole aperture.   
      
   What's wrong with it?   
      
   w.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)