TIR & Escape-Cone Calculator

Critical angle, escape fraction, guided fraction and the minimum cladding thickness — for the geometry you actually have, not the textbook one.

Three geometries in one tool: an isotropic emitter inside the core (LED die), an edge-fed light guide (Monte Carlo over a Lambertian in-air source), and a guided beam at a stated angle (waveguide combiner). Reports the critical angle, escape or guided fraction, side-by-side isotropic-vs-edge-fed comparison, evanescent penetration depth, and the minimum cladding thickness at a chosen per-bounce leak budget. Warns when the evanescent tail is deeper than the cladding.