Compact Three Mirror Anastigmat Space Telescope Design using 6.5m Monolithic Primary Mirror

TL;DR

This paper presents a compact, high-performance 6.5m monolithic primary mirror three-mirror anastigmat telescope design, optimized for space and ground applications with wide field of view and diffraction-limited imaging.

Contribution

The paper introduces a novel TMA telescope design with a 6.5m monolithic primary mirror, emphasizing compactness, simplicity, and superior optical performance over traditional two-mirror systems.

Findings

Achieves diffraction-limited performance across the entire field of view.

Offers improved tolerance and simplified fabrication compared to RC telescopes.

Enables efficient wavefront correction for active/adaptive optics in space and ground.

Abstract

The utilization of a 6.5m monolithic primary mirror in a compact three-mirror anastigmat (TMA) telescope design offers unprecedented capabilities to accommodate various next generation science instruments. This design enables the rapid and efficient development of a large aperture telescope without segmented mirrors while maintaining a compact overall form factor. With its exceptional photon collection area and diffraction-limited resolving power, the TMA design is ideally suited for both the ground and space active/adaptive optics concepts, which require the capture of natural guide stars within the field of view for wavefront measurement to correct for misalignments and shape deformation caused by thermal gradients. The wide field of view requirement is based on a statistical analysis of bright natural guide stars available during observation. The primary mirror clear aperture, compactness requirement, and detector pixel sizes led to the choice of TMA over simpler two-mirror solutions like Ritchey-Chretien (RC) telescopes, and the TMA design offers superior diffraction-limited performance across the entire field of view. The standard conic surfaces applied to all three mirrors (M1, M2, and M3) simplify the optical fabrication, testing, and alignment process. Additionally, the TMA design is more tolerant than RC telescopes. Stray light control is critical for UV science instrumentation, and the field stop and Lyot stop are conveniently located in the TMA design for this purpose.