The measure method for eccentricity of large aperture aspheric mirror

Due to the large size of large-aperture aspheric mirrors and the long optical path each of them needs to inspect, the deviation of the optical axis from the structural reference cannot be accurately measured by conventional inspection means. However, as the aperture of the optical lens increases, alignment puts higher requirements on the concentricity of the optical axis of the mirror with the axis of the structure. Excessive eccentricity leads to severe consequences, including interference of the lens’ optomechanical structure, and non-adjustable misalignment. In this study, the accurate measurements of all the optical parameters of the mirror were realized by building an inspection optical path with mirror, measuring the spatial position of the apex of each optical component structure using a laser tracker, and testing the mirror through rotations. The conventional inspection methods and the inspection method of this study were simultaneously applied to the aspherical mirror with a diameter of 448 mm. Through the test results, it has been proven that the method proposed in this study is feasible.