Techniques and technologies for shroud and baffle design in reflective triplet freeform telescopes

Unobscured freeform optical imaging systems have seen increasingly frequent design attention over the past two decades, particularly in the reflective triplet design format. While the optical and mechanical design of these systems has received much attention, comparatively little is published regarding the technologies and techniques useful in designing shrouds to manage stray light for these systems. We will explore several areas of shroud and baffle design for compact reflective triplets, including first-order design, vane placement, manufacturing methods, surface scatter, and useful surface treatments. Leveraging custom computational scripts, a scatterometer (CASI), and FRED software simulations, a complete shroud is designed and evaluated through simulation of the point source transmission. Several challenges are revealed for the compact freeform reflective triplet form factor, such that the stray light suppression of these telescopes may be sub-optimal despite methodical shroud design. This indicates that imaging scenarios with high sensitivity to stray light may see significant challenges if designed using a highly compact reflective triplet design form.