Radiant Source Models

Near-field luminance models for real light sources

Radiant Source Models (RSMs) provide the most accurate method of modeling the near-field output of real light sources for use in optical and illumination design software. They are used for light source analysis to investigate fine scale performance for light source design and development and for optical and illumination design to create accurate performance simulations. RSMs can be used by optical and illumination design engineers to simulate virtually any type of light source, including LEDs, fluorescent lights, arc, tungsten halogen and HID lamps.

RSM data files are available as downloads from our extensive library of light source measurements or via our measurement service for new light source models. RSMs can be used to generate ray sets that are compatible with leading optical and illumination design software such as ASAP, FRED, LightTools, Photopia, SimuLux, SPEOS, TracePro, and ZEMAX. Ray set generation from am RSM data file requires a ProSource software licence.

Complete Information for Light Source Performance Evaluation

It is often difficult or impossible for an engineer to obtain all of the data necessary to accurately model a light source with traditional means, such as combining various shapes in optical design software and applying estimated luminance values to each component. An RSM avoids this limitation by measuring the true luminance field (both angular and spatial distributions) of a representative light source using a state-of-the-art Source Imaging Goniometer (SIG) system.

The resulting RSMs are comprised of luminance — and colorimetric, if a colour measurement is made — images of the light source from many viewing angles. This collection of source images provides the optical designer with tremendous flexibility in investigating the performance of the light source. Anomalous or discontinuous performance can be directly investigated by viewing the relevant measurement images using ProSource software.

Accurate Ray Sets Using Importance Sampling Improves Optical Design

Using ProSource, RSMs can be used to generate ray sets for export to optical design software with full control over the number of rays generated (from a few million rays for a rough design to tens of millions of rays for a final, detailed design), the angular range of the rays, the total luminous flux of the ray set, and the ray origin.

ProSource uses “importance sampling” to generate efficient ray sets, with results that are superior to traditional Monte Carlo methods for generating ray sets. By taking the full near-field data into account, importance sampling associates rays with meaningful source features, and so obtains the same accuracy in representing the source with only 20% of the number of rays required with Monte Carlo methods. Importance sampling can only be done if the full near-field data is available, as in RSMs.

This reduction in the number of rays that must be analysed allows faster processing in optical design software — saving time and allowing more options to be evaluated without sacrificing accuracy.

Try it Yourself!

Demonstration versions of selected RSMs and ProSource software are available as downloads (see the link to downloads to the right). The Radiant Source Model demo files contain a sample data set that enables visual inspection of the model but not ray set generation. Ray generation requires that you purchase a full RSM file and a ProSource software licence.

The demo version of ProSource software is a fully functional version of the programme, however, it only allows access to the RSM demo files. A security key and a licence code must be ordered to use it with standard RSM files - contact Pro-Lite for this.