As others said you can use a parabolic reflector to direct the light in one direction. I think this can work: On one side place a parabolic reflector to direc

As others said you can use a parabolic reflector to direct the light in one direction. I think this can work: On one side place a parabolic reflector to direct the light in one direction. On the other side place a circular reflector to direct the light back to the source. And place a tiny hole in this half circle to let the light out. Quick drawing: http://zenphoton.com/#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 http://zenphoton.com/#AAQAAkACAAEgWwAzALEBEwC0AO4A/wAAtADxAL...