System and method for robust fingerprint acquisition
First Claim
1. A combined multispectral and total-internal-reflectance biometric system, wherein the combined multispectral and total-internal-reflectance biometric system comprises:
- a platen having a plurality of facets, wherein at least one facet comprises a surface target facet;
a first illumination source disposed to illuminate the surface target facet along a first illumination path that encounters the surface target facet at a first angle measured from a normal to the surface facet that is less than a critical angle, the critical angle defining a smallest angle measured from the normal at which light incident on the surface target facet substantially undergoes total-internal-reflectance;
a second illumination source disposed to illuminate the surface target facet along a second illumination path that encounters the surface target facet at a second angle measured from the normal that is greater than the critical angle; and
an imaging system comprising a first imaging location and a second imaging location;
wherein;
the imaging system is disposed to receive light propagated from the first illumination source after scattering at the surface target facet at the first imaging location; and
the imaging system is disposed to receive light propagated from the second illumination source when total-internal-reflectance is substantially frustrated by the presence of the purported skin site on the surface target facet at the second imaging location.
2 Assignments
0 Petitions
Accused Products
Abstract
Combined multispectral and total-internal-reflectance biometric imaging systems are disclosed. A platen has multiple facets, at least one of which has a surface adapted for placement of a purported skin site by an individual and another facet may include an optical absorber. An illumination source and an optical arrangement are disposed to illuminate the purported skin site with light from the illumination source along distinct illumination paths, including paths at angles less than the critical angle and paths at angles greater than the critical angle. Both multispectral and total-internal-reflectance illumination are received by an imaging system. The imaging system may include first and second imaging locations adapted to record images from separate illumination paths. The platen may also include non parallel exits facets.
298 Citations
25 Claims
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1. A combined multispectral and total-internal-reflectance biometric system, wherein the combined multispectral and total-internal-reflectance biometric system comprises:
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a platen having a plurality of facets, wherein at least one facet comprises a surface target facet; a first illumination source disposed to illuminate the surface target facet along a first illumination path that encounters the surface target facet at a first angle measured from a normal to the surface facet that is less than a critical angle, the critical angle defining a smallest angle measured from the normal at which light incident on the surface target facet substantially undergoes total-internal-reflectance; a second illumination source disposed to illuminate the surface target facet along a second illumination path that encounters the surface target facet at a second angle measured from the normal that is greater than the critical angle; and an imaging system comprising a first imaging location and a second imaging location; wherein; the imaging system is disposed to receive light propagated from the first illumination source after scattering at the surface target facet at the first imaging location; and the imaging system is disposed to receive light propagated from the second illumination source when total-internal-reflectance is substantially frustrated by the presence of the purported skin site on the surface target facet at the second imaging location. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A combined multispectral and total-internal-reflectance biometric imaging system comprising:
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a platen having a plurality of facets, at least one of the facets comprising a surface target facet; an illumination source; an optical arrangement disposed to illuminate the purported skin site with light from the illumination source along a plurality of distinct illumination paths, wherein a first illumination path encounters the surface target facet at a first angle measured from a normal to the surface target facet and is less than a critical angle, and a second illumination path encounters the surface target facet at a second angle measured from the normal to the surface target facet and is greater than the critical angle, the critical angle defining a smallest angle measured from the normal at which light incident on the surface target facet substantially undergoes total-internal-reflectance; and an imaging system disposed to receive light from the surface target facet and comprising a first imaging location and a second imaging location; wherein; light propagated from the illumination source along the first illumination path is received by the imaging system at the first imaging location after scattering at the surface target facet; and light propagated from the illumination source along the second illumination path is received by the imaging system at the second imaging location when total-internal-reflectance is substantially frustrated by the presence of a biometric feature on the surface target facet. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A method of capturing multispectral and total-internal-reflectance biometric images, wherein the method comprises the steps of:
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propagating light from an illumination source along a first illumination path and encounters a surface target facet of a platen at a first angle measured from a normal to the surface target facet that is less than the critical angle, the critical angle being defined as the smallest angle measured from the normal at which light incident on the surface target platen is substantially totally reflected; collecting light propagated from the illumination source along the first illumination path with an imaging system at a first imaging location; propagating light from an illumination source along a second illumination path that encounters the surface target platen at a second angle measured from the normal to the surface target facet that is greater than then critical angle; and collecting light propagated from the illumination source along the second illumination path with the imaging system at a second imaging location; wherein; light propagated along the first illumination path is collected by the imaging system after scattering by the surface target; and light propagated along the second illumination path is collected by the imaging system when total-internal-reflectance is frustrated by the presence of a purported skin site at the surface target. - View Dependent Claims (22)
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23. A biometric imaging system, wherein the biometric imaging system comprises:
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a platen with a plurality of facets; first illumination source; a second illumination source; and an imaging system; wherein; at least one facet of the platen comprises a surface target adapted to receive a purported skin site; the imaging system is disposed to receive light scattered from the surface target facet along a first illumination path and a second illumination path; light from the first light source enters the platen through a first entrance facet; light from the second light source enters the platen through a second entrance facet that is not parallel with the first entrance facet; light scattered from the surface target facet along the first illumination path exits the platen through a first exit facet; light scattered from the surface target facet along the second illumination path exits the platen through a second exit facet; and the first exit facet and the second exit facet are not parallel. - View Dependent Claims (24, 25)
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Specification