A CMOS-based angle measurement method with common-path polarized-light difference

In order to address the challenge of high-precision angular deformation measurement of the star sensor bracket for the Macau Science satellite-1, a PSD-based autocollimation method for angle measurement using common-path polarized light difference was proposed previously. A measurement system was developed, enabling high-precision measurement of the bracket's angular deformation under vacuum and high-low temperature conditions. However, deficiencies such as large non-linear errors in PSD and significant effects of scattered light on measurements within the system were identified. To address these challenges, this study proposes a CMOS-based angle measurement method using common-path polarized light difference. Additionally, a centroid algorithm for spot detection was designed, and simulations were conducted using Zemax. Finally, a setup was constructed, and calibration experiments based on PSD and CMOS were carried out across different measurement ranges. The results revealed that within the measuring range of ±500″, the maximum calibration deviation for PSD was 3.1″, while for CMOS, it was 1.2″. These findings demonstrate the enhanced measuring range and precision achieved by the proposed CMOS-based method.