Fingerprint identification device
First Claim
1. A fingerprint identification device for rapid automatic comparison of a latent fingerprint with a known fingerprint, comprising:
- a light source illuminating said latent print;
optical projection means interposed between said fingerprints projecting the image of said latent fingerprint in an optical path and superimposing said image on said known fingerprint, said optical projection means including;
a pair of independent coaxial image forming lenses symmetrically disposed with respect to a common intermediate image plane, each of said lenses having an aperture stop location associated therewith,optical deflection means positioned at each of said aperture stop locations causing said image to traverse said known fingerprint in a repeating pattern, andoptical rotation means effectively rotating said image in said optical path;
sensing means positioned adjacent said known fingerprint, said sensing means being responsive to the radiance produced by the interaction of said image with said known fingerprint and emitting an electrical signal representative of said radiance;
signal processing means connected with said sensing means comparing said signal with a preestablished correlation signal threshold; and
indicator means responsive to said signal processing means and actuated thereby when said signal exceeds said threshold to indicate the matching of said fingerprints.
1 Assignment
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Accused Products
Abstract
A device employing the optical autocorrelation method for automatically comparing the fingerprint of an individual with a previously identified exemplar utilizes a pair of multifaceted mirrors rotating about mutually perpendicular axes to sweep an image of the fingerprint over the surface of the exemplar in a raster. To maintain the image in focus, a pair of independent identical relay lens systems are positioned in the light path and arranged symmetrically with respect to a common intermediate image plane. The mirrors are positioned so that as they rotate their reflective facets coincide successively with the aperture stop locations of the respective lens system. To compensate for possible angular misalignment of the fingerprint and the exemplar, novel independent optical means are provided for effectively rotating the image about the principal axis of the light path.
34 Citations
10 Claims
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1. A fingerprint identification device for rapid automatic comparison of a latent fingerprint with a known fingerprint, comprising:
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a light source illuminating said latent print; optical projection means interposed between said fingerprints projecting the image of said latent fingerprint in an optical path and superimposing said image on said known fingerprint, said optical projection means including; a pair of independent coaxial image forming lenses symmetrically disposed with respect to a common intermediate image plane, each of said lenses having an aperture stop location associated therewith, optical deflection means positioned at each of said aperture stop locations causing said image to traverse said known fingerprint in a repeating pattern, and optical rotation means effectively rotating said image in said optical path; sensing means positioned adjacent said known fingerprint, said sensing means being responsive to the radiance produced by the interaction of said image with said known fingerprint and emitting an electrical signal representative of said radiance; signal processing means connected with said sensing means comparing said signal with a preestablished correlation signal threshold; and indicator means responsive to said signal processing means and actuated thereby when said signal exceeds said threshold to indicate the matching of said fingerprints. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Optical projection means for superimposing the image of a latent fingerprint on a known fingerprint in a fingerprint identification device, comprising:
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a pair of independent, coaxial image forming lenses symetrically disposed with respect to a common intermediate image plane, each of said lenses having an aperture stop location associated therewith; optical deflection means positioned at each of said aperture stop locations causing said image to traverse said known fingerprint in a repeating pattern; and optical rotation means effectively rotating said image in said optical path. - View Dependent Claims (8, 9, 10)
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Specification