Latent fingerprint detectors and fingerprint scanners therefrom
First Claim
1. A method of detecting surface contaminants, comprising:
- illuminating a sample surface with a first light source to produce specular reflection from the sample surface;
capturing the specular reflection from the sample surface with an optical detector arranged at a critical alignment angle relative to the first light source;
generating image data with the optical detector using the specular reflection to generate image data of the sample surface;
discriminating against diffuse reflection by said first light source and said optical detector having substantially equal and opposite numerical apertures with geometric filtering; and
analyzing said generated image data of the sample surface with a processor to determine if said generated image data includes an image of a surface contaminant.
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Abstract
This document relates to systems and method for latent fingerprint detection using specular reflection (glare). An exemplary system may include a light source alignment portion configured to align a light source at an illumination angle relative to a sample surface such that the light source illuminates a sample surface so that the surface produces specular reflection. The system may also include a specular reflection discriminator that directs the produced specular reflection to an optical detector aligned relative to said sample surface at an alignment angle that is substantially equal to an angle of reflection of the produced specular reflection. Preferably, the directed specular reflection does not saturate the optical detector; and the optical detector captures the specular reflection from the sample surface and generates image data using essentially only the specular reflection.
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Citations
13 Claims
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1. A method of detecting surface contaminants, comprising:
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illuminating a sample surface with a first light source to produce specular reflection from the sample surface; capturing the specular reflection from the sample surface with an optical detector arranged at a critical alignment angle relative to the first light source; generating image data with the optical detector using the specular reflection to generate image data of the sample surface; discriminating against diffuse reflection by said first light source and said optical detector having substantially equal and opposite numerical apertures with geometric filtering; and analyzing said generated image data of the sample surface with a processor to determine if said generated image data includes an image of a surface contaminant. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for detecting a surface contaminant, comprising:
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illuminating a sample surface to produce specular reflection with a light source alignment portion that aligns a light source at an illumination angle relative to the sample surface; directing the specular reflection with a specular reflection discriminator to an optical detector aligned relative to the sample surface at an alignment angle that is substantially equal to an angle of reflection of the specular reflection such that the directed specular reflection does not saturate the optical detector, the optical detector and the light source have substantially equal and opposite numerical apertures to create geometric filtering to discriminate against diffuse reflection; capturing the specular reflection from the sample surface with the optical detector; and generating image data using essentially only the specular reflection to generate image data of the sample surface. - View Dependent Claims (10, 11, 12, 13)
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Specification