Non-Sequential Ray Tracing

Non-Sequential ray tracing is a core technology in Zemax. It is a powerful and general technology for tracing rays in systems where there are multiple optical paths. Typical uses include:

1. Illumination systems, especially those with multiple or complex optical sources
2. Systems like interferometers, in which light that has travelled through several different optical systems must be coherently recombined
3. Stray light analysis in otherwise sequential optical systems
    

The non-sequential paradigm is that there is no pre-defined path for any ray. A ray is launched and hits whatever object is in its path, and it may then reflect, refract, diffract, scatter, split into child rays etc. It is a far more general technology than sequential ray-tracing, and is therefore somewhat slower in terms of ray-tracing speed.

In the non-sequential component editor, a list of objects is set out. The order of the objects in this list does not matter (there are a few exceptions to this: see the Geometry Creation section for details).

Rays propagate from the source object until they hit an object, at which point they may partially reflection, transmit, scatter or diffract:

In this case, approximately 1% of the energy is reflected by the MgF₂-coated N-BK7 prism faces, and approximately 50% is reflected/transmitted by the coating on the hypoteneuse face where the two prisms touch. New rays (called 'child' rays) are launched to take this energy away, and so a complete picture of where the energy goes in the system is produced.

Related Knowledge Base articles:
Exploring Non-Sequential Mode in Zemax