Hi guys.

Trying to understand how LEDs project/form their beams. I took a macro photo of
a 10mm led and together with the datasheet, I deduced that the front of the LED
is a perfect sphere, and the LED emitting junction is just at the opposite end
of that sphere ('imaginary', as the body of the led is cylindrical there).
(eg. http://spie.org/x34513.xml)

First weirdness: with some math I seem to have deduced that, if the focal point
is indeed that spot, the IOR of the material should be 2.0 which is a very
exotic value for LED epoxies (from the docs I could find on the internet).

So I entered the above as a scene in povray, and have been suffering since :(

Questions: 

Can I put a light source inside the epoxy? Or do I have to make a small
bubble? 

I tried to enable photon mapping, but couldn't seem to get it working. Is
there some simple example - say a sphere + light + plane? Does this
work with the light inside an object?

The light seems to pass through the epoxy without refraction...

Enabling caustics, does give some lensing, but not realistically.

John

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