Impact of cryogenic mirror deformation on asymmetric spatial heterodyne interferometers and its correction

To address the problem of interference fringe distortion and wind velocity retrieval errors caused by thermally induced surface deformation in a spaceborne long-wave infrared Doppler asymmetric spatial heterodyne interferometer operating in a low-temperature vacuum environment, a systematic study on aberration mechanisms and phase compensation methods was carried out. First, based on integrated opto-mechanical-thermal analysis, a surface deformation model of the optical system under the −113 °C operating condition was established. The surface errors were fitted and modeled using Zernike polynomials, revealing that thermally induced surface deformation primarily introduces low-order aberrations such as spherical aberration and astigmatism. Subsequently, the mechanism by which these aberrations generate additional optical path differences was analyzed. The results show that they lead to fringe bending, reduced contrast, and non-uniform spatial distribution, thereby degrading phase extraction accuracy and introducing wind velocity retrieval errors. Finally, a phase-domain compensation method based on Zernike polynomials was proposed to correct the interferometric phase and suppress the influence of thermally induced surface deformation on system performance. Simulation results demonstrate that the proposed method effectively restores the spatial characteristics of the interference fringes, reducing the wind velocity retrieval error by approximately 62.5%. This effectively mitigates the impact of thermal surface deformation and ensures wind measurement accuracy under extremely low-temperature conditions.