Calibration for Industrial Optical High-Resolution Microimaging Systems

Due to issues stemming from unclear models, limited microfeatures, and the poor robustness of algorithms, estimating calibration parameters for optical high-resolution microimaging systems has proven to be a challenging task. In this article, we propose a grid-full-size active-based calibration (GAC) method to address these aforementioned limitations. We establish a parallel projection model within a high-resolution microimaging system to describe the camera calibration process. The full size of a single grid on the resolution board is accurately obtained through a robust subpixel feature extraction method, allowing us to estimate the homography matrix. In conjunction with the parallel projection model, we introduce a novel homography matrix decomposition method to provide initial parameter estimation. To enhance feature richness, we employ active control of the piezoelectric microplatform and improve global optimization to achieve precise parameter estimation. A comprehensive series of experiments has been conducted, and the results demonstrate a mean square error of 5.25 nm. Furthermore, in large-stroke experiments, the GAC method enables a displacement precision of 658 nm for standard deviation errors within a measurement range of 0–100 mm.