Cryogenic temperature compensation design for the optical structure of The Earth 2.0 (ET) Transit Telescope

This study addresses the thermal-structural matching challenge faced by the optical system of The Earth 2.0 (ET) Transit Telescope (comprising nine lenses with apertures of 276–344 mm) operating at –15 ℃. An optomechanical design integrating a two-stage flexible support structure with coefficient of thermal expansion (CTE)-matched materials is proposed, coupled with a low-temperature displacement pre-compensation method. By establishing a coupled thermal-structural-optical model, the predicted deformation is used as a feedforward correction in the alignment process to actively compensate for image quality drift under cryogenic conditions. The resulting system achieves an EE90 radius variation of less than 0.5 μm at –15 ℃, significantly enhancing on-orbit stability and providing a valuable reference for the development of similar cryogenic optical systems.