鋁合金TMA離軸光學系統研發

Research and Development of All Aluminum-Alloy Small-Scale Three-Mirror Anastigmatic Telescope

此計畫為發展一套實驗體全鋁合金的小型TMA（Three-Mirror Anastigmatic）離軸光學系統。傳統的太空用途望遠鏡光學系統在結構和鏡片部分都必須採用昂貴且特殊的低膨脹係數的材料，來避免異材料間的熱膨脹不匹配的問題。本研究發展一套包含鏡片與結構均採用鋁合金製造之望遠鏡，其光學系統採用實驗體TMA架構，包含主鏡、次鏡及三鏡等三片非球面鏡片，光學面採用超精密加工成型。此小型TMA光學系統的有效焦長為110.0mm，焦比為f／6.0，水平與垂直方向視角分別為20度與2度。這套實驗體望遠鏡的鏡片組已經完成製造並且在太空中心的光學實驗平台上完成光學校準實驗研究，並且於2018年完成光機系統的設計。

The project is to develop a small-scale experimental TMA (Three-Mirror Anastigmatic) off-axis optical system entirely made of aluminum alloy. Conventional space-use telescope optical systems must use expensive and special low CTE (Coefficient of Thermall Expansion) materials in both the structural and lens sections to avoid thermal expansion mismatch between heterogeneous materials. However, a telescope with lenses and structures entirely made of aluminum alloy was developed in this study. The optical system adopts experimental TMA architecture with three aspherical mirrors, such as primary mirror, secondary mirror, and tertiary mirror, which are made by diamond turning precision machining. This small-scale TMA optical system has an effective focal length of 110.0 mm, a focal ratio of f/6.0, and horizontal and vertical viewing angles of 20 and 2 degrees, respectively. These three mirrors of the experimental telescope have been made and setup on the optical bench at National Space Organization (NSPO) for the study of off-axis optical alignment process. In addition, the opto-mechanical design of the telescope was accomplished in the end of 2018.