On Friday, January 31, 2014 6:18:23 AM UTC-5, Michael Balda wrote:   
   > I'd like to use a pattern projector for computer vision tasks. The pattern   
   can be in the NIR range, should not repeat itself but doesn't need to be   
   described exactly, so random noise, speckle etc. should be fine. It would be   
   preferrable, if the pattern    
   can be restricted to a defined field of view instead of being omni-directional   
   and was stable over time. Of course there are several different approaches but   
   I would like to find one which is    
   >    
   > (a) cheap,    
   >    
   > (b) robust,    
   >    
   > (c) efficient (in terms of power consumption),    
   >    
   > (d) not too complex,   
   >    
   > (e) has good availability of components and    
   >    
   > (f) is monochromatic or has small bandwidth.   
   >    
   >    
   >    
   > Thanks in advance for any suggestions.   
      
   well, without knowing more, here is a rather speculative approach:    
   Put a bright led into a fluid bath in a test tube and point it where you want   
   to. Put small mica or similar particles in the fluid, so that they stay in   
   suspension. (Glitter from crafts store possible.) Then, based on the thermal   
   currents from the led (   
   or a helper resistor below it.), you will see a "near field" projection of   
   patterns. If you sand off the plastic enclosure on the led, it will magnify   
   the effect, but try without first. The trick with this sort of thing is to get   
   a dense fluid, and    
   perchloroethylene dry cleaning fluid a good choice. With water, plastic flakes   
   would be best, since they have low density.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)