Influence of thermal deformation on irradiance of a collimating optical system used in radiometric calibration

In order to solve the problem of prodigious temperature fluctuation for a collimating optical system used in radiometric calibration in simulated space application, the study on influence of thermal deformation on irradiance of the collimating optical system composed of an off-axis paraboloidal reflector is presented in this paper. Firstly, the mechanical model for the optical system is initiated by SOLIDWORKS. Next, the thermo-mechanical coupling analysis of optical and mechanical structures is performed by means of finite-element method via ANSYS. Then, the geometric model for the deformed optical system is established due to the analysis result. Finally, the irradiance of this deformed optical system is analyzed by the Monte-Carlo ray-tracing analysis. The results indicate that the irradiance change induced by surface deformation of the off-axis paraboloidal reflector with a PV error of 0.161λ and a RMS error of 0.026λ (λ = 632 nm) is less than 0.4%. It is found that the influence of the rigid body displacement of the paraboloidal reflector on the irradiance change is larger, and in the edge of the region where the grid irradiance is weaker, the irradiance change is about 3%.