Device for forming and detecting fingerprint images with valley and ridge structure
First Claim
1. A device for producing an image of a fingerprint having ridges and valleys, said device comprising:
- light producing means for producing light rays;
a light transmitting substrate capable of transmitting the light produced by said light producing means;
a fingerprint illuminating region for physical placement of a finger bearing a fingerprint;
an image detection means for detecting an image of said fingerprint;
an optical element affixed to a portion of said light transmitting substrate and being disposed between said fingerprint illuminating region and said image detection means, said optical element embodying a light diffracting grating;
wherein said fingerprint illuminating region, said optical element and said image detection means are each disposed substantially along a common optical axis; and
wherein during the operation of said device,(1) light rays produced by said light producing means, propagate within said light transmitting substrate towards said optical element and are diffracted by said light diffracting grating,(2) diffracted light rays produced by said light diffracting grating, propagate directly towards said fingerprint illuminating region and fall incident upon and are intensity modulated by the ridges and valleys of said fingerprint, and(3) intensity modulated light rays produced from said ridges and valleys propagate directly back through light transmitting substrate and said optical element and fall incident upon said image detection means, whereupon an image of said fingerprint is detected, said detected image including information corresponding to said ridges and valleys of said fingerprint.
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Accused Products
Abstract
A method and ultra-compact system has been developed for illuminating and detecting the surface topography of an object such as the finger of an individual. The system is capable of producing high-contrast images which can be electronically transmitted in real-time, or stored using electronic or photographic recording devices. Light traveling within a light transmitting substrate is redirected by a slanted-fringe light diffractive grating preferably embodied within a volume hologram. The volume hologram, either of the reflection or transmission type, is attached to the light transmitting substrate, and functions to diffract light striking thereupon and illuminate an object having topographical surface structure. After being spatially and intensity modulated in accordance with topographical details of the illuminated object, the modulated light passes back through the light transmitting substrate and the volume hologram, onto an image detection array, for subsequent analysis. Each of the disclosed embodiments has a compact geometry suitable for use in diverse object identification applications.
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Citations
35 Claims
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1. A device for producing an image of a fingerprint having ridges and valleys, said device comprising:
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light producing means for producing light rays; a light transmitting substrate capable of transmitting the light produced by said light producing means; a fingerprint illuminating region for physical placement of a finger bearing a fingerprint; an image detection means for detecting an image of said fingerprint; an optical element affixed to a portion of said light transmitting substrate and being disposed between said fingerprint illuminating region and said image detection means, said optical element embodying a light diffracting grating; wherein said fingerprint illuminating region, said optical element and said image detection means are each disposed substantially along a common optical axis; and wherein during the operation of said device, (1) light rays produced by said light producing means, propagate within said light transmitting substrate towards said optical element and are diffracted by said light diffracting grating, (2) diffracted light rays produced by said light diffracting grating, propagate directly towards said fingerprint illuminating region and fall incident upon and are intensity modulated by the ridges and valleys of said fingerprint, and (3) intensity modulated light rays produced from said ridges and valleys propagate directly back through light transmitting substrate and said optical element and fall incident upon said image detection means, whereupon an image of said fingerprint is detected, said detected image including information corresponding to said ridges and valleys of said fingerprint. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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Specification