Enhancing collimator calibration precision with sub-pixel resolution using composite periodic patterns

This paper proposes a high-precision collimator calibration method based on the principle of the vernier caliper. Collimators are crucial in the development phase of satellite telescopes, as they generate parallel light beams to adjust the focal plane of the satellite optical system, ensuring that satellites can accurately target and maintain optimal operational performance in orbit. Traditionally, laser interferometry is used to calibrate collimators. Although laser interferometry provides high-precision calibration, it is costly and time-consuming, requiring a precise five-axis motion platform to record the coordinates of the interferometer at specific focal points. Therefore, we propose a method using composite periodic patterns to enhance the accuracy of collimator calibration. We utilize an optical imaging system composed of a lens with an effective focal length of 1000 mm and an image sensor with a pixel size of 3.45 micrometers to calibrate a collimator with a focal length of 10500 mm. By analyzing the periodic patterns captured at different aperture positions of the collimator, we achieve sub-pixel level positioning accuracy. This method improves the measurement accuracy of the collimator, providing a low-cost yet highly accurate calibration solution.