The video below demonstrates FRED's Single Raytrace functionality, which is a very useful debugging and analysis capability that allows the extraction of customizable ray data at each surface intersection along the ray's path. One common use for this feature is to verify the correctness of an imported CodeV or Zemax optical model by performing a single raytrace in FRED and comparing the results to the same calculation performed in CodeV or Zemax. Another common use case is to track the material assignment of a ray as it propagates through the system.
An example Cooke Triplet design is provided below as a simple model to test the functionality with.
Example FRED file: SingleRaytrace_TripletExample.frd