Difference between Frensel reflection and Total Internal Reflection

hairbair

What exactly is the difference between Frensel reflection and total internal reflection with regards to the efficiency of an LED? Do they both occur at the semiconductor/ air interface? I am a bit confused, thanks for the help.

jsgruszynski

Not difference - they are related.

* Fresnel reflection: one interface reflected like a transmission line due to impedance/refractive index discontinuity

* Total internal reflection: two interfaces spaced just at the right distance to constructively reflect or cancel, where each interface has Fresnel reflection

dlgoff

There's a interface between epoxy/plastic and air.



These lenses are designed to get the light out.



But they can't get it all out.




Thanks to http://zeiss-campus.magnet.fsu.edu/a...rces/leds.html for the images.