| 摘要 |
A fingerprint identification device is provide that includes a light source for emitting light coupled to a transparent prism having a slant surface to which a fingerprint being identified is contacted and in which light from the light source is directed for creating a fingerprint image. A CCD array is disposed a distance from the transparent prism, for receiving an image from the prism. An inexpensive lens is spaced between the CCD array and the prism, for focusing light received from the prism onto the CCD so that an image can be detected. Conveniently a diaphragm is coated on the periphery of a face of the lens about its outer edge for preventing some of the light propagating from the prism in the direction of the lens, from reaching the CCD array. Advantageously, providing the diaphragm on the lens lessens Gaussian distortion and increases depth of field, conveniently, the location of the diaphragm is fixed directly on the lens, obviating careful placement and affixing of a discrete diaphragm about a focal point of the lens.
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