Astronomers and astrophysicists studying the nature of celestial objects require clear, sharp images collected by astronomical telescopes. To accomplish this, the engineers who design and build these instruments must ensure that light from the target reaches the instrument focal plane without unwanted contributions from bright sources such as the Sun, Earth, or Moon. This is accomplished by performing a stray light analysis. A stray light analyst finds the propagation paths of unwanted light through the telescope's optomechanical structure and adds baffles to block this light before it gets to the detector. This work is typically performed with the aid of elaborate computer software and models. Stray light analysis software was developed by and for the aerospace industry, but in recent years these same tools have found uses in the development of commercial photonic products.