Ray data sources are sources that emit rays as if they were emitting from an actual source, but without any structural information. Many source vendors provide ray data files for their sources in lieu of providing proprietary geometrical and optical information about their sources. You may also wish to replace a complex source model with a simple ray data file for quicker simulation speeds. Ray data files originate from measured data of actual sources, or from LightTools simulations where rays are recorded on a receiver and exported into a ray data file.
The number of rays in these files typically range from a few thousand rays to millions of rays. For example, the LightTools LED Library (Tools > LED Library) contains ray data files for 5,000 rays for each LED. 5,000 rays is typically insufficient for practical modeling, so it is intended that users will contact their vendor to obtain ray data files with much larger numbers of rays. As with any source, the more rays that are traced during a simulation means that there will be higher accuracy. However, there are trade-offs to consider when using these large ray data files:
- The simulation time will be long
- The ray data file size will be large
At intermediate steps during the design process, you might wish to sacrifice some accuracy for quicker simulations or smaller file sizes.
Subsampling the Ray Data Source for Faster Simulation Times
When you want to trace a smaller subset of rays from the larger ray data file, go to the ray data source’s Ray Trace tab. Enabling the “Use Subsampling” option will let you tell LightTools how many rays from the ray data file you’d like to use, and LightTools will pick that many rays from the file in a random order and scale the power of the subsampled rays to match the total power of the source.