Compute refraction angles across an optical interface by Snell's law.
| Item | Formula / Note | Source / Standard |
|---|---|---|
| Snell's law | n1·sinθ1 = n2·sinθ2 with refractive indices n | Snell 1621 (published by Descartes 1637) |
| Common refractive indices | Air 1.0003, water 1.333, crown glass 1.52, diamond 2.42 at 589 nm | Optical-materials handbooks |
| Dispersion | n varies with wavelength; Abbe number Vd quantifies dispersion | Abbe 1874 dispersion definition |
| Reversibility | Light paths are reversible; the ray retraces in reverse | Basic geometrical-optics principle |