Analysis and correction of environmental differences in geometric performance of spaceborne optical instruments

High precision laboratory geometric calibration is the basis for the validity of on-orbit data of the Directional Polarimetric Camera. However, the difference in refractive index between the laboratory geometric calibration environment and the on-orbit vacuum environment can lead to changes in instrument geometric performance. The geometric performance difference of the instrument in the standard atmospheric environment and vacuum environment was analyzed by Zemax. The image point position deviation of the instrument in the two environments increases monotonically with the FOV. The image point position in the standard atmospheric environment is further away from the optical axis. When the FOV of the incident beam is 60o , the image points position deviation in all bands is greater than 1.42 pixels. Then, the laboratory carried out the environmental difference verification experiment based on the geometric performance verification light source. The experimental results are in good agreement with the Zemax analysis results, and the average deviation in the 670 nm band is less than 0.01 pixel. Finally, the laboratory geometric model parameters of the Directional Polarimetric Camera are corrected according to the Zemax analysis results. The corrected geometric model parameters will effectively improve the on-orbit geolocation and image registration accuracy of the Directional Polarimetric Camera.