Cassegrain Telescope Builder

A while ago, I was reading through Joe Geary’s excellent book, “Introduction to Lens Design” 1, and it occurred to me that his first order construction of a Cassegrain telescope could be very easily written up as a BASIC script in FRED.

The example file that accompanies this document contains three embedded scripts.

makeCassegrain – Implement’s Joe Geary’s method of constructing a Cassegrain telescope with some basic input construction parameters.  Also creates a default plane wave source, sequential paths, and some simple baffle geometry.

makeImportanceSamples – Implements a paraxial approach to automating the construction of importance samples for scattering calculation.

assignScatterProperties – Automates the assignment of scatter models and raytrace controls to geometry that is created by the makeCassegrain script.

After running the automated scripts, the user will have a simple Cassegrain telescope system with baffle geometry, importance sample specifications applied to the optical surfaces which target the telescope focal plane, and scatter models and raytrace controls assigned to the geometry in preparation for scatter calculations.

I find that this set of scripts is particularly useful for quickly generating a meaningful (but simple) opto-mechanical system on which I can test various modeling scenarios.

1. Geary, Joseph M. Introduction to Lens Design: With Practical Zemax Examples.  Willmann-Bell: Richmond, 2007.  (Amazon Link)

Download the PDF: Cassegrain Telescope Builder

Download the FRED file: cassegrainTelescopeBuilder_v2.frd