Hi Kevin,
I developed a sequential ray tracing application for Fusion 360 that lets the user select their rays (as construction lines), lens or refractive surfaces, and mirrors, and then propogates the rays through the optical system. You can select multiple rays to see where an image plane would be formed, for example, and it is all done in the sketch environment. It doesn't have as many features as some dedicated optical simulation softwares do, but does allow sequential ray tracing and is a user-friendly interface for the less demanding optomechanical engineering systems. I use it to find image plane placement or prototype some non-standard optical sytems.
The program works by calculating Snell's law for each surface and treats mirrors as perfect mirrors. For curved surfaces, a tiny differential line is created to approximate the curve in order to calculate the angles needed for the refraction or reflection. You can set parameters for your refractive indicies or manually type in the numbers. If you'd like to try it, the program is available on the Autodesk App store here:
https://apps.autodesk.com/FUSION/en/Detail/Index?id=6116739023577696095&os=Win64&appLang=en
More info:
https://www.apereon.com/raytracer
https://www.youtube.com/watch?v=Ih3xSgTnWiY
