A fast, wide-field and distortion-free telescope with curved detectors for surveys at ultra-low surface brightness

TL;DR

This paper introduces a novel all-reflective, wide-field, distortion-free Schmidt telescope design with curved detectors, optimized for ultra-low surface brightness surveys, combining high image quality and manufacturability.

Contribution

The paper presents a new telescope design with an anamorphic primary mirror and curved detectors, enabling wide-field, low-distortion imaging suitable for space-based surveys.

Findings

Design achieves high image quality without spider diffraction

Manufacturable primary mirror via stress polishing

Prototype suitable for future space missions

Abstract

We present the design of an all-reflective, bi-folded Schmidt telescope aimed at surveys of extended astronomical objects with extremely-low surface brightness. The design leads to a high image quality without any diffracting spider, along with a large aperture and field of view, with a small central obstruction which barely alters the PSF. As an example, we present the design of a high-quality, 36 cm diameter, fast ( f /2.5) telescope working in the visible with a large field of view (1.6{\deg}x 2.6{\deg}). The telescope can operate with a curved detector (or with a flat detector with a field flattener) and a set of filters. The entrance mirror is anamorphic and replaces the classical Schmidt entrance corrector plate. We show that this anamorphic primary mirror can be manufactured through stress polishing, avoiding high spatial frequency errors, and tested with a simple interferometer scheme. This prototype is intended to serve as a fast-track scientific and technological pathfinder for the future space-based MESSIER mission.