Homebrew PCBs

I know that this can (will) be problematic. As angle of led is around 
120 degrees it's unusable as is. If I make aperture of 0.2mm at the led 
then beam 1mm far from led is over 3mm wirdh. So I need to colimate that 
light to be more paralel. But the 1'st test to be made is if LED can 
develop emulsion at all. So if "flash" of 0.5 second from 2-3mm distance 
is enought the project may sucess..



On 09/18/2013 06:43 PM, designer_craig wrote:
> The problem with the LED is the light is pattern is most likely 110 to 140 degree. Even if you had a 20X objective lens below your aperture mask the mask hole for a .128mm spot is only going to be 2.5mm.  Without some serious low loss collimination of the LED energy you are not going to get very many joules of LED light energy on the Riston.  Riston publishes the exposure energy in joules required, do the calculations.  The nice thing about the laser is all the energy is sort of in the same direction to start with.
> Craig
>
>