A novel camera calibration method for deflectometry system

Phase measuring deflectometry (PMD) is a well-established method to evaluate specular surface shape by detecting gradient data. In a PMD measurement, camera calibration plays a significant role. Using classical camera calibration methods to calibrate PMD system, the root mean square (RMS) of reprojection error can only be achieved for around 0.3 pixels. Therefore improvement for an accurate camera calibration in a PMD system is a special focus for PMD research. In this paper, a novel calibration method is presented to enhance camera calibration accuracy in a deflectometry system. Before calculating the initial value of internal and external parameters of the camera, pixel-by-pixel distortions are compensated by the proposed algorithm based on active phase target. Experimental results demonstrate that the proposed calibration method can effectively reduce the RMS of reprojection errors to 0.0237 pixels.