Proto-Model of an Infrared Wide-Field Off-Axis Telescope

TL;DR

This paper presents a prototype of an off-axis infrared wide-field telescope with a simple two-mirror design, demonstrating its manufacturing, alignment, and imaging capabilities for potential mid-infrared applications.

Contribution

The paper introduces a novel off-axis Schwarzschild-Chang type telescope prototype with practical manufacturing and alignment procedures for infrared wide-field observations.

Findings

Successful fabrication and surface analysis of off-axis mirrors

Effective alignment using ray tracing methods

Basic imaging test confirms system performance

Abstract

We develop a proto-model of an off-axis reflective telescope for infrared wide-field observations based on the design of Schwarzschild-Chang type telescope. With only two mirrors, this design achieves an entrance pupil diameter of 50 mm and an effective focal length of 100 mm. We can apply this design to a mid-infrared telescope with a field of view of 8 deg X 8 deg. In spite of the substantial advantages of off-axis telescopes in the infrared compared to refractive or on-axis reflective telescopes, it is known to be difficult to align the mirrors in off-axis systems because of their asymmetric structures. Off-axis mirrors of our telescope are manufactured at the Korea Basic Science Institute (KBSI). We analyze the fabricated mirror surfaces by fitting polynomial functions to the measured data. We accomplish alignment of this two-mirror off-axis system using a ray tracing method. A simple imaging test is performed to compare a pinhole image with a simulated prediction.