Ray tracing

Ray tracing is a light-propagation simulation method in which the behavior of light rays — reflection, refraction, absorption, and scattering — is calculated geometrically at successive surfaces of an optical system.

How does ray tracing work?

The method assumes light can be modeled as a set of rays with a defined direction, energy, and spectrum, instead of a full electromagnetic wave. This simplification is justified when the optical elements are much larger than the wavelength of light.

• Sequential ray tracing — rays pass through surfaces in a fixed order, used when designing lenses and objectives
• Non-sequential ray tracing — rays can hit any surface multiple times, essential for illumination and stray light analysis

Applications

Ray tracing is used in designing LED reflectors and lighting systems, lenses and imaging systems, stray light analysis in space and military instruments, and simulating vehicle lighting and AR/VR displays.

Related terms

Sequential ray tracing

Non-sequential ray tracing

Monte Carlo method in optics