Non-sequential ray tracing

Non-sequential ray tracing is a variant of ray tracing in which a light ray can hit any surface of the 3D model, in any order, reflecting, refracting, and scattering multiple times.

How does non-sequential ray tracing work?

Unlike the sequential approach, no surface order is predefined here — the ray moves freely across the entire geometry of the mechanical-optical system, just as real light does inside a luminaire or an instrument housing. This usually requires a Monte Carlo simulation with millions of rays to obtain a reliable statistical result.

Applications

This method is essential for designing LED luminaires, reflectors, projection systems, and light pipes, as well as for stray light analysis in space instruments, telescopes, and cameras, where every unwanted light reflection matters.

Related terms

Sequential ray tracing

Stray light

Monte Carlo method in optics