/sci/ - Science & Math

I made a lens that focuses light coming from any direction into a thin beam going in the same direction, by having a glass sphere with a shell made of some sort of material that has a <1 index of refraction.
I've been testing it with large beams of light, with the intent of concentrating the beams with the lens into small beams.
However, I honestly have no idea what I'm doing.
What I've found is that thinning the shell will, to some extent, help focus the beam. Dunno if it causes more light to scatter out of the lens, probably does.
Bringing the IoR down close to zero has a much more profound effect in focusing the beam, but definitely causes more light to scatter out.
Anyone know how I can optimise this to have an extremely narrow beam without losing 99% of the light going into the lens?