A real-time, VanderLugt-type optical correlator with a single SLM has been developed. A field programmable gate array was used to capture and process images obtained from a CCD camera at a rate of 60 video fields per second. During both enrollment and verification, a finger slides over a glass prism and is input to the system via the frustration of total internal reflection. An auto-enrollment procedure captures the optimal image during each slide. An optimal composite filter is implemented. The correlation detection process comprises real-time tracking of the correlation peak while the finger is sliding, and a decision process based on projective decision boundaries. Real-life tests yielded a false rejection rate of 1% and a false acceptance rate of 0.2%.
"High-speed fingerprint verification using optical correlator", Proc. SPIE 3386, Optical Pattern Recognition IX, (23 March 1998); doi: 10.1117/12.304769; https://doi.org/10.1117/12.304769