Prism
Refracts through all three drawn BK7-like boundaries with wavelength-dependent dispersion.
Open in the canvas →In the real world
A prism disperses light because its refractive index depends on wavelength. Each face refracts according to Snell's law:
Since n itself varies with λ, different colors refract by different amounts and separate — this is why white light fans into a rainbow. Real optical glass is characterized by a Sellmeier equation, a sum of resonance terms fit to measured data, not a single simple formula.
In OpticalSetup
Each face is a genuine refracting boundary — incident rays bend by real vector Snell's law, and a ray that exceeds the critical angle undergoes total internal reflection instead of exiting, exactly as a real prism does. For dispersion, broadband and supercontinuum beams are sampled at several discrete wavelengths across their band, and each sample refracts with its own wavelength-dependent index, so the beam visibly fans into a spectrum.
The dispersion formula above is a deliberately simplified stand-in for real BK7 glass, tuned to give the right qualitative shape (more bending at blue wavelengths, less at red) rather than matching a real glass catalog to several decimal places. Only one glass "family" is modeled; there's no coating, absorption, or surface-quality loss beyond the configured per-face transmission.