Geometrical error calibration in reflective surface testing based on reverse Hartmann test

Abstract

In the fringe-illumination deflectometry based on reverse-Hartmann-test configuration, ray tracing of the modeled testing system is performed to reconstruct the test surface error. Careful calibration of system geometry is required to achieve high testing accuracy. To realize the high-precision surface testing with reverse Hartmann test, a computer-aided geometrical error calibration method is proposed. The aberrations corresponding to various geometrical errors are studied. With the aberration weights for various geometrical errors, the computer-aided optimization of system geometry with iterative ray tracing is carried out to calibration the geometrical error, and the accuracy in the order of subnanometer is achieved.

Simulation of display thermal deformation and error analysis in high precision reverse Hartmann test

“…Due to reverse Hartmann measures the slope of each point on the mirror and then reconstructs the surface shape through integration or polynomial fitting, the measurement precision is highly dependent on the accuracy of system calibration. Geometric error and camera distortion are mainly considered and have been theoretically derived [7][8]. There is little study on the deformation of optical components.…”