The Opto-Mechanical–Thermal Coupling Analysis and Verification of an All-Aluminum Freeform Imaging Telescope

A freeform imaging telescope (FIT) can achieve a large field of view, high resolution, light weight, and small volume at the same time. Single-point diamond turning (SPDT) is usually used to fabricate FITs, which made entirely aluminum alloy. Compared with traditional telescope, whose reflector glass structure aluminum, coefficient thermal expansion (CTE) non-conforming, CTE in an all-aluminum FIT identical. Therefore, it was expected theoretically have athermalization properties. In this paper, off-axis three-mirror verified. The opto-mechanical–thermal coupling analysis −20 °C carried out, including data processing coordinate transformation. node deformation global coordinates obtained from finite-element were converted into XY polynomial coefficients local system ZEMAX. results showed that modulation transfer function (MTF) °C~+40 still reached diffraction limit. Moreover, MTF 0.291 through environmental test, almost as 22 °C. These could