Reflection and transmission at an interface — s/p polarization, Brewster angle, total internal reflection
The Fresnel equations give the reflection and transmission coefficients for light crossing a boundary between two media. This calculator computes reflectance and transmittance as a function of incidence angle for both s- and p-polarization, using the complex refractive index of any material in the database. Enter the two media and a wavelength to plot R and T across all angles.
The plot marks Brewster's angle, where p-polarized reflectance drops to zero, and the critical angle for total internal reflection when light passes from a denser to a rarer medium. For absorbing media the coefficients follow from the complex Fresnel formulas, so metals and lossy films are handled directly. An optical-power mode converts reflectance into reflected and transmitted power for a given input.