Optical EngineeringHybrid optical/digital access control using fingerprint identification
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Two hybrid optical/digital systems for access control applications in real-time fingerprint identification are presented. Both involve fingerprint acquisition with a prism, optical Fourier transformation by a lens, data reduction using a wedge-ring detector (WRD), and decision making with a digital computer. One, called the coherent system, performs the Fourier transformation on a coherent fingerprint image introduced directly from a prism, and the other, called the incoherent system, acquires an incoherent fingerprint image, performs preprocessing in a digital computer, and incoherent-to-coherent image conversion before coherent processing. Both systems use the total internal reflection obtained in a prism to introduce the fingerprint image. Decision making is performed by a computer on the WRD output, a feature vector of 64 component digital values. In our experiment, discrimination and error-tolerance performance associated with our two access control systems were tested with four different fingerprints. Initial experimental results show that the incoherent system achieves better performance at the expense of additional equipment.