Telescope Model Using OAPs
This knowledge base article demonstrates modeling of a three mirror 5x afocal telescope system as prescribed in “Modern Lens Design: A Resource Manual” by Warren Smith (McGraw Hill). This article discusses how to construct the off-axis parabolas (OAPs) in FRED using the surface apertures to select the off-axis portion of a base surface. Additionally, a custom script is used to trace a “gut ray” along the optical axis so that the decenter position can be accurately identified for the 2nd and 3rd mirrors of the system. Finally, an analysis surface is placed at the output plane to verify the system MP.
Download the PDF: Modeling-a-3-mirror-5x-afocal-telescope.pdf
Download the FRED file: 3-Mirror-5x-afocal.frd