Latent fingerprint detection

Abstract

Systems, devices, and methods for detecting a contaminant on a substrate are discussed herein. Variations of such systems, devices, and methods may include one or more illumination sources that emit illumination at one or more desired wavelength ranges to illuminate one or more areas on the substrate; where the desired wavelength range is one that is absorbed by the contaminant while causing the substrate to fluoresce. Such fluorescence may be detected with a visible-spectrum detector, which will also detect the contaminant as a darker contrast area against the fluorescence. In some variations, an illumination source includes a broad-spectrum light source and a waveband filtering device that filters all but the desired illumination waveband out of the broad-spectrum light generated by the broad-spectrum light source.

Description

PRIORITY[0001]The present Application claims benefit of priority to U.S. provisional application 61 / 573,077, filed Aug. 26, 2011; 61 / 530,306, filed Sep. 1, 2011; 61 / 538,020, filed Sep. 22, 2011; 61 / 602,950, filed Feb. 24, 2012; 61 / 602,956, filed Feb. 24, 2012; 61 / 606,886, filed Mar. 5, 2012; and 61 / 606,898, filed Mar. 5, 2012, the entire contents of all of which are hereby incorporated by reference.TECHNICAL BACKGROUND[0002]Currently, fingerprint detection technologies are limited to trial-and-error techniques to locate a fingerprint-bearing surface, and yet more trial-and-error techniques to bring the fingerprint into relief against the surface to render it visible / scannable.[0003]Optical detection of latent fingerprints is critically dependent on image contrast. Latent fingerprints are very low contrast objects and therefore using only optical techniques they are difficult to resolve / collect. Lifting latent fingerprints often requires the use of chemical techniques (i.e. processin...

AI Technical Summary

Benefits of technology

The patent describes a device that filters out unwanted light in a way that preserves the desired waveband. It achieves this by using a flash lamp that emits a broad-spectrum of light, and then filters out the excessive unwanted light using a special optical filter. This results in a higher proportion of ultraviolet light and a lower proportion of visible and near-infrared light in the emitted light. The device's trigger circuit ensures that the activation pulse width is limited to only the desired waveband. Overall, this technology allows for better control over the light emitted by a flash lamp and improves the quality of the desired waveband.

Problems solved by technology

Currently, fingerprint detection technologies are limited to trial-and-error techniques to locate a fingerprint-bearing surface, and yet more trial-and-error techniques to bring the fingerprint into relief against the surface to render it visible / scannable.

Latent fingerprints are very low contrast objects and therefore using only optical techniques they are difficult to resolve / collect.

Lifting latent fingerprints often requires the use of chemical techniques (i.e. processing by ninhydrin) and significant time (3+days) to lift the fingerprints, which may damage the surface and / or destroy any underlying DNA or material evidence included in the fingerprint (i.e. traces of whatever the person leaving the print may have handled previously)

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