Fingerprint comparator

Claim 1

An apparatus for rapid automatic comparison of two patterns, each located and oriented randomly within a bounded plane area, comprising: a source of intense incoherent light illuminating a first one of said patterns; optical projection means interposed between said patterns optically superimposing the image of said first pattern on the second of said patterns, said optical projection means including spaced first and second coaxial lenses so arranged that the periphery of the image of said first pattern projected by said first lens into said second lens is vignetted by said second lens; scanning means positioned between said optical projection means and said second pattern causing said image to traverse said second pattern in a repeating scan raster; rotation means effectively rotating said scan raster with respect to said second pattern about an axis passing through said second pattern and normal to the plane thereof; sensing means responsive to the radiance produced by the interaction of said image with said second pattern positioned adjacent said second pattern, said sensing means emitting an electrical signal whose amplitude and frequency are representative of said radiance; electrical signal processing means connected with said sensing means electrically comparing the amplitude of said signal with a preestablished correlation amplitude 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 patterns.

Claim 2

An apparatus for rapid automatic comparison of two patterns, each located and oriented randomly within a bounded plane area, comprising: a source of intense incoherent light illuminating a first one of said patterns; optical projection means interposed between said patterns optically superimposing the image of said first pattern on the second of said patterns, said optical projection means including spaced first and second coaxial lenses so arranged that the periphery of the image of said first pattern projected by said first lens into said second lens is vignetted by said second lens; scanning means positioned between said optical projection means and said second pattern causing said image to traverse said second pattern in a repeating scan raster; rotation means effectively rotating said scan raster with respect to said second pattern about an axis passing through said second pattern and normal to the plane thereof; sensing means responsive to the radiance produced by the interaction of said image with said second pattern positioned adjacent said second pattern, said sensing means emitting an electrical signal whose amplitude and frequency are representative of said radiance; electrical signal processing means connected with said sensing means electrically comparing the amplitude of said signal with a preestablished correlation amplitude 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 patterns.

Claim 3

An apparatus for rapid automatic comparison of two patterns, each located and oriented randomly within a bounded plane area, comprising: a source of intense incoherent light illuminating a first one of said patterns; optical projection means, including spaced coaxial first and second lenses, interposed between said patterns optically superimposing the image of said first pattern on the second of said patterns; image apodizing means associated with said optical projection means for spatial filtering of said image, including an opaque mask positioned intermediate said lenses and having an aperture therethrough lying on the optical axis of said lenses inside the focus of said first lens; scanning means positioned between said optical projection means and said second pattern causing said image to traverse said second pattern in a repeating scan raster; rotation means effectively rotationg said scan raster with respect to said second pattern about an axis passing through said second pattern and normal to the plane thereof; sensing means responsive to the radiance produced by the interaction of said image with said second pattern positioned adjacent said second pattern, said sensing means emitting an electrical signal whose amplitude and frequency are representative of said radiance; electrical signal processing means connected with said sensing means electrically comparing the amplitude of said signal with a preestablished correlation amplitude 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 patterns.

Claim 4

An apparatus for rapid automatic comparison of two patterns, each located and oriented randomly within a bounded plane area, comprising: a source of intense incoherent light illuminating a first one of said patterns; optical projection means, including spaced coaxial first and second lenses, interposed between said patterns optically superimposing the image of said first pattern on the second of said patterns; image apodizing means associated with said optical projection means for spatial filtering of said image, including an opaque mask positioned intermediate said lenses and having an aperture therethrough lying on the optical axis of said lenses inside the focus of said first lens; scanning means positioned between said optical projection means and said second pattern causing said image to traverse said second pattern in a repeating scan raster; rotation means effectively rotationg said scan raster with respect to said second pattern about an axis passing through said second pattern and normal to the plane thereof; sensing means responsive to the radiance produced by the interaction of said image with said second pattern positioned adjacent said second pattern, said sensing means emitting an electrical signal whose amplitude and frequency are representative of said radiance; electrical signal processing means connected with said sensing means electrically comparing the amplitude of said signal with a preestablished correlation amplitude 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 patterns.

Claim 5

An apparatus for rapid automatic comparison of two pAtterns, each located and oriented randomly within a bounded plan area, comprising: a source of intense incoherent light illuminating a first one of said patterns; optical projection means interposed between said patterns optically superimposing the image of said first pattern on the second of said patterns; image apodizing means associated with said optical projection means for spatial filtering of said image; scanning means positioned between said optical projection means and said second pattern causing said image to traverse said second pattern in a repeating scan raster, said scanning means comprising a pair of reflectors positioned in the optical path of the image of said first pattern projected from said optical projection means, said reflectors being mounted for oscillating rotation about mutually perpendicular axes of rotation, and a pair drivers driving said reflectors in oscillating rotary motion about said axes, thereby imparting scanning motion to said image; rotation means effectively rotating said scan raster with respect to said second pattern about an axis passing through said second pattern and normal to the plane thereof; sensing means responsive to the radiance produced by the interaction of said image with said second pattern positioned adjacent said second pattern, said sensing means emitting an electrical signal whose amplitude and frequency are representative of said radiance; electrical signal processing means connected with said sensing means electrically comparing the amplitude of said signal with a preestablished correlation amplitude 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 patterns.

Claim 6

An apparatus for rapid automatic comparison of two pAtterns, each located and oriented randomly within a bounded plan area, comprising: a source of intense incoherent light illuminating a first one of said patterns; optical projection means interposed between said patterns optically superimposing the image of said first pattern on the second of said patterns; image apodizing means associated with said optical projection means for spatial filtering of said image; scanning means positioned between said optical projection means and said second pattern causing said image to traverse said second pattern in a repeating scan raster, said scanning means comprising a pair of reflectors positioned in the optical path of the image of said first pattern projected from said optical projection means, said reflectors being mounted for oscillating rotation about mutually perpendicular axes of rotation, and a pair drivers driving said reflectors in oscillating rotary motion about said axes, thereby imparting scanning motion to said image; rotation means effectively rotating said scan raster with respect to said second pattern about an axis passing through said second pattern and normal to the plane thereof; sensing means responsive to the radiance produced by the interaction of said image with said second pattern positioned adjacent said second pattern, said sensing means emitting an electrical signal whose amplitude and frequency are representative of said radiance; electrical signal processing means connected with said sensing means electrically comparing the amplitude of said signal with a preestablished correlation amplitude 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 patterns.

Claim 17

An apparatus for rapid automatic comparison of two patterns, each located and oriented randomly within a bounded plane area, comprising: an incandescent lamp illuminating a first of said patterns with incoherent light; an optical projector projecting the image of said first pattern along an optical path; an image apodizer positioned in said optical path to vignette said image; a holder supporting said second pattern for rotation about an axis passing through said second pattern and normal to the plane thereof; a pair of oscillating reflectors positioned in said optical path and cooperating to scan said apodized image across said second pattern in a repeating scan raster; a photodetector positioned to sense the incoherent radiance produced by the interaction of said apodized image and said second pattern and to emit an electrical signal in response to said radiance; an electrical signal processing circuit connected to said photodetector and responsive thereto, said circuit including, in series, a preamplifier, a high-pass filter, and automatic gain control amplifier, and a threshold; and an indicator actuated by the output of said circuit when said output exceeds a preestablished threshold amplitude, thereby indicating the matching of said patterns.

Claim 18

An apparatus for rapid automatic comparison of two patterns, each located and oriented randomly within a bounded plane area, comprising: an incandescent lamp illuminating a first of said patterns with incoherent light; an optical projector projecting the image of said first pattern along an optical path; an image apodizer positioned in said optical path to vignette said image; a holder supporting said second pattern for rotation about an axis passing through said second pattern and normal to the plane thereof; a pair of oscillating reflectors positioned in said optical path and cooperating to scan said apodized image across said second pattern in a repeating scan raster; a photodetector positioned to sense the incoherent radiance produced by the interaction of said apodized image and said second pattern and to emit an electrical signal in response to said radiance; an electrical signal processing circuit connected to said photodetector and responsive thereto, said circuit including, in series, a preamplifier, a high-pass filter, and automatic gain control amplifier, and a threshold; and an indicator actuated by the output of said circuit when said output exceeds a preestablished threshold amplitude, thereby indicating the matching of said patterns.

Claim 19

An apparatus for rapid automatic comparison of two patterns, each located and oriented randomly within a bounded plane area, comprising: a base; a first holder fixed to said base for receiving and releasably holding a first one of said patterns; a second holder spaced from said first holder for receiving and releasably holding the second of said patterns; a high-intensity incandescent lamp secured to said base adjacent said first holder; an ellipsoidal dichroic reflector of very low F-number secured to said base and directing high-intensity incoherent illumination from said lamp onto said first pattern; a first opaque mask secured to said base adjacent said first pattern and having an opening therethrough limiting the field of the image of said first pattern visible through said mask; an optical projection assembly secured to said base intermediate said patterns, said assembly including first and second spaced lenses and a second opaque mask having an image apodizing aperture therethrough positioned intermediate said lenses with said aperture on the optical axis of said lenses and spaced from the focal point of said first lens; a first reflector secured to said base and positioned to direct the image of said first pattern visible through said first mask into said first lens; a second reflector positioned in the optical path of the image emitted by said projector and mounted to said base for limited oscillatory rotation about an axis perpendicular to said path; a third reflector positioned adjacent said second reflector and in the optical path of the image reflected thereby, said third reflector being mounted to said base for limited oscillatory rotation about an axis parallel with the optical path of the image emitted by said projector, said second and third reflectors being so positioned with respect to said second holder to superimpose the image reflected by said second reflector onto said second pattern; a pair of drivers mounted to said base and effectively connected to said second and third reflectors to drive said reflectors, thereby scanning the image of said first pattern over the face of said second pattern in a repeating scan raster; a mount secured to said base and supporting said second holder for limited rotation thereof about an axis passing through said second pattern and normal thereto; a motor secured to said base and effectively connected to drive said second holder, thereby causing said second pattern to rotate with respect to said scan raster; a photodetector mounted to said base adjacent the edge of said secOnd pattern to receive and respond to incoherent radiance produced by the interaction of the illuminated image of said first pattern with said second pattern; a fourth reflector mounted to said base and positioned adjacent the edge of said second pattern remote from said photodetector to reflect illumination from said second pattern into said photodetector; an electrical signal processing circuit connected to the output of said photodetector, said circuit including a pre-amplifier, a high-pass filter, an automatic gain control amplifier and a threshold; and an indicator connected to said signal processing circuit and actuated thereby, when the output of said automatic gain control amplifier excees a preestablished correlation amplitude threshold, to indicate the matching of said patterns.

Claim 20

An apparatus for rapid automatic comparison of two patterns, each located and oriented randomly within a bounded plane area, comprising: a base; a first holder fixed to said base for receiving and releasably holding a first one of said patterns; a second holder spaced from said first holder for receiving and releasably holding the second of said patterns; a high-intensity incandescent lamp secured to said base adjacent said first holder; an ellipsoidal dichroic reflector of very low F-number secured to said base and directing high-intensity incoherent illumination from said lamp onto said first pattern; a first opaque mask secured to said base adjacent said first pattern and having an opening therethrough limiting the field of the image of said first pattern visible through said mask; an optical projection assembly secured to said base intermediate said patterns, said assembly including first and second spaced lenses and a second opaque mask having an image apodizing aperture therethrough positioned intermediate said lenses with said aperture on the optical axis of said lenses and spaced from the focal point of said first lens; a first reflector secured to said base and positioned to direct the image of said first pattern visible through said first mask into said first lens; a second reflector positioned in the optical path of the image emitted by said projector and mounted to said base for limited oscillatory rotation about an axis perpendicular to said path; a third reflector positioned adjacent said second reflector and in the optical path of the image reflected thereby, said third reflector being mounted to said base for limited oscillatory rotation about an axis parallel with the optical path of the image emitted by said projector, said second and third reflectors being so positioned with respect to said second holder to superimpose the image reflected by said second reflector onto said second pattern; a pair of drivers mounted to said base and effectively connected to said second and third reflectors to drive said reflectors, thereby scanning the image of said first pattern over the face of said second pattern in a repeating scan raster; a mount secured to said base and supporting said second holder for limited rotation thereof about an axis passing through said second pattern and normal thereto; a motor secured to said base and effectively connected to drive said second holder, thereby causing said second pattern to rotate with respect to said scan raster; a photodetector mounted to said base adjacent the edge of said secOnd pattern to receive and respond to incoherent radiance produced by the interaction of the illuminated image of said first pattern with said second pattern; a fourth reflector mounted to said base and positioned adjacent the edge of said second pattern remote from said photodetector to reflect illumination from said second pattern into said photodetector; an electrical signal processing circuit connected to the output of said photodetector, said circuit including a pre-amplifier, a high-pass filter, an automatic gain control amplifier and a threshold; and an indicator connected to said signal processing circuit and actuated thereby, when the output of said automatic gain control amplifier excees a preestablished correlation amplitude threshold, to indicate the matching of said patterns.