>    
   >    
   > In general you're better off doing absolutely every possible optical    
   >    
   > thing to get more light onto a smaller detector before resorting to cooling.   
   >    
   >    
   >    
   > CCDs are a horse of another colour.  Getting more light in an    
   >    
   > astronomical telescope, say, or a fluorescence microscope, may be very    
   >    
   > expensive, and the pixels can be only so small.   
   >    
   I've got this issue that I want to detect particles in a tube about 1 mm ID.   
   The particles are about 15 microns diameter. Their volume fraction about 1   
   percent. So I can take a cylindrical lens, say, and focus it on the   
   cylindrical target, and then onto    
   the CCD array. The illuminating light, coming from the opposite side, will   
   converge as focused by the cylinder. This is reminding me of the design of a   
   slide projector!    
      
   One aspect of a ccd array - I posted a question on another group - is the   
   software to work with individual pixels. From the viewpoint of a metrology   
   engineer, imaging reduces the BW by being able to segment individual parts,   
   yet many imaging systems don'   
   t have that transparency.    
      
   So at this point I am going on the astronomy groups to see what SW packages   
   they have for this. I spent much time in past programming OCR, and you need   
   pixel programming control to get the info out. So that's where I stand. An   
   ounce of tradecraft in this    
   worth a pound of theory.   
      
   JB   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)