Stepped Advanced Raytrace with Analyses
It is important to remember that Analysis Surfaces in FRED only post-process (filter) rays at the end of the raytrace when an analysis is requested. They do not collect ray information during the raytrace, regardless of whether the ray trajectory passes through the analysis grid. So the question becomes, “how do I analyze the optical field in an optical space for rays passing through that space during the raytrace?”
One option would be to use FRED’s Detector Entity constructs. Detector Entities are similar to Analysis Surfaces except that they can be inserted into any optical space and can collect ray information dynamically during the raytrace (i.e. as rays pass through their collection grid). Currently, Detector Entities do not work with coherent or polarized rays and can only perform Irradiance, Illuminance and Color Image analyses.
The purpose of this KB article is to demonstrate how you can setup your geometry and Analysis Surfaces in such a way that a simple script can be used to access ray information at any position during the raytrace.
Download the article PDF: Stepping and Advanced Raytrace with Analyses
Download the FRED file: steppedARTwithAnalysisExample.frd