From: oh2hvj@sral.fi   
      
   M.A. Sonjariv  writes:   
      
   > I was involved in this exact LED to fiber coupling issue a few years   
   > ago. The only way we found to efficiently (and that is relative)   
   > couple multiple  LED's into a fiber was to have a 6 around 1 fiber   
   > bundle built with each of the 7 ends being independent and the 7   
   > mounted together with a diffuser on the delivery end. We butt coupled   
   > each independent end to each  of 7 fibers getting >50% of each LED   
   > launched.  You can substitute 7 with a different number but it can be   
   > unweildly as the number of fibers increases.   
      
   Thank you for sharing your expecience. Almost-direct coupling   
   would also allow for using smaller LED power and still get   
   the same optical output power.   
      
   And thank you for also other commenters on this thread!   
      
   Dichroic combining would be too expensive for this application,   
   but I've successfully tested that for splitting light from   
   a single 1mm fiber to multiple filters+photodiodes.   
   In that case the reason for using fiber was that the lght   
   was coming from a spark emission having huge EMC issues   
   for any electronics.   
      
   --   
   Mikko   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)