Nonholonomic spherical stitching measurement method for large-aperture angles based on differential confocal precise surface fixation

Compared with traditional stitching measurements, the limited positioning accuracy of subaperture adjustment leads to a low measurement accuracy. Herein, a method based on a differential confocal precise surface fixation for large-aperture angle nonholonomic spherical surface stitching measurements is proposed. In this method, precise positioning of the confocal point is achieved through differential confocal fixed surface technology, by constructing a stitching model to convert the coordinates of subaperture data and unify the coordinate system. The stitching measurement of the spherical surface shape is realized by analyzing the wavefront aberration introduced by the adjustment error and compensating for the error through precise focusing. Adaptive correction of the eccentricity error is achieved, and high-precision stitching measurement of large-aperture angle nonholonomic spherical surfaces is realized. A differential confocal interference stitching measurement system was built, and simulation experiments indicated that the stitching measurement accuracy of the proposed method can reach 0.0018λ and that the relative error can reach 1.90%. This method provides an accurate method for the acquisition of subaperture confocal surfaces and allows high-precision stitching measurement of large-aperture angle spherical surfaces.