High-precision measurement and control of geometric parameters of off-axis aspheric surface

Modern space optical remote sensors use many off-axis aspheric surfaces to improve performance and increase the field of view. The geometric parameters of the off-axis aspheric surface include its vertex radius of curvature and aspheric surface coefficients, which have an important influence on the performance of the remote sensor. With the continuous improvement of remote sensor performance indicators, the aspheric surface diameter and vertex radius of curvature continue to increase, and the tolerances are becoming more and more strict. Traditional geometric parameter measurement methods such as three-coordinates and compensator control cannot meet the requirements. In order to achieve high-precision measurement of geometric parameters of aspheric surfaces, a laser tracker cooperated with CGH to measure geometric parameters was researched. The structure of CGH is simple, and the optical reference is easy to accurately establish, convert and reproduce. The tracker has high measurement accuracy and wide range. Its software can model and calculate angle relationships, and can perform spatial measurement and positioning of complex optical paths with folding mirrors. Using the simple structure of CGH and the laser tracker to accurately measure the distance, the aspheric surface detection optical path high-precision positioning (0.01mm) and optical axis reference lead (5") to meet the tolerance requirements of geometric parameters. Through simulation analysis and experimental verification. The calculation accuracy of the vertex curvature radius can reach 0.01%, and the accuracy of the aspheric coefficient can reach 0.0001.