From: diverse@tcp.co.uk   
      
   A bright light source consisting of 3 rings of high power white LEDs.   
   Each LED with a heaxagonal periphery 6 degree beam-spread lens. All   
   lenses set on a spherical surface of 62mm radius. So 1 central LED plus   
   lens, then 6 , then 12 then 12. Concentrates the light to the centre of   
   the sphere in a square about 10mm x 10mm. This is a working cluster.   
   If I wanted to increase the light at this spot would the following work?   
   Remove the central LED and lens. Another 31 LED arrangement as the   
   original. In the axial centre, now, an array of domes cut and polished   
   hemispheres , from the tops of 5mm water clear basic LEDs.   
   The flat surfaces of these close packed 5mm hemispheres set again to   
   a spherical "surface" to redirect the incoming  light axially. Any idea   
   what proportion of the outer set of light reaching 10mm diameter of the   
   intermediary "focus" would reach the next "focus" of 10mm diameter ?   
   Just approximate 70 percent / 80/90?   
   Or any other kitchen-table "engineering" solution?   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)