Local subaperture compensation and stitching interferometry

This paper proposes an interferometry method based on a fixed interferometer structure and locally compensated stitching. The subaperture measurement is completed by applying a double-optical-wedge compensator in the "rugged" area of the surface that cannot be measured. The data of the measured area is stitched to obtain the local surface shape. The calibration of the double-optical-wedge compensator is performed by using a standard mirror. Surface figure error (SFE) of the standard mirror is measured by an interferometer beforehand. Compared with the SFE measured after adding the compensator in the optical path, the phase and aberration of the double-optical-wedge can be obtained. Measured data is processed by the subaperture stitching algorithm. Through the weighted fusion algorithm, the corresponding data values on the overlapping areas are weighted, and different weights are assigned to different areas to make the stitching transition smooth. Based on the principle of interferometry, a double-optical-wedge compensation measurement system is designed and implemented. A simulation model of the measurement experiment is presented, and the validity of the method is verified by simulation.