Thermal deformation suppression method for chalcogenide glass based on deep cryogenic treatment

In infrared optical system, changes of the reflective index will result in a decrease in imaging quality. Therefore, athermalized treatment is necessary. Chalcogenide glasses (As40Se60) are the ideal material for thermal aberration correction in infrared optical systems, which have excellent infrared optical properties, especially the transmission performance and temperature characteristics. However, thermal deformation is inevitable for chalcogenide glasses in the coating process, which is a major cause of quality deterioration. In this paper, a deep cryogenic treatment with a series of specific parameters is carried out and a comparative experiment is conducted. The result shows that the thermal stability of chalcogenide glass in the coating process is improved markedly after deep cryogenic treatment. The thermal deformation of the optical surface is reduced and the surface accuracy is controllable.