Many LEDs are encapsulated in silicone. In regard to butt coupling light into a plastic light guide with similar index, my question: is it better to have a small air gap or not?
My most immediate issue with simulating this is that if I put the source (ideal Lambertian emitter) ‘Inside Of’ a silicone object, a larger fraction of the rays TIR inside… I’m guessing this needs a more sophisticated model, but I’m mostly looking for general advice. Any thoughts or guidance will be appreciated.