Latent fingerprint detectors and fingerprint scanners therefrom

• US 8,805,033 B2
• Filed: 11/02/2011
• Issued: 08/12/2014
• Est. Priority Date: 11/03/2010
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Miesak, Edward, Gold, V. Edward
• Primary Examiner(s): DULANEY, KATHLEEN YUAN
• Application Number:
  US13/976,177
• Publication Number:
  US 20130301887A1
• Time in Patent Office: 1,014 Days
• Field of Search: 382/124, 382/312, 356/71
• US Class Current: 382/124
• CPC Class Codes: G01N 21/8851 Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges G01N21/8806 and G01N21/93 - G01N21/95692 take precedence; optical measurement of dimensions G01B11/00; optical scanning G02B26/10; image transformation G06T3/00; computerised image enhancement G06T5/00; image processing per se for flaw detection G06T7/0002
• CPC Class Codes: G01N 21/94 Investigating contamination, e.g. dust G01N21/85 takes precedence
• CPC Class Codes: G01N 2201/06113 Coherent sources; lasers
• CPC Class Codes: G01N 2201/10 Scanning
• CPC Class Codes: G06V 40/1312 direct reading, e.g. contactless acquisition

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.

Claims

1. A latent fingerprint detection system, comprising;

a first light source that illuminates a sample surface such that the sample surface produces specular reflection;

an optical detector arranged at a critical alignment angle relative to the first light source such that the optical detector captures the specular reflection from the sample surface and generates image data using the specular reflection to generate image data of the sample surface; and

an image processor configured to;

analyze said generated image data to determine if said generated image data includes a fingerprint; and

produce image data of the fingerprint responsive to a determination that said analyzed image data includes the fingerprint;

wherein said first light source and said optical detector comprise substantially equal and opposite numerical apertures.

2. The system of claim 1, wherein said optical detector is aligned relative to said sample surface at an alignment angle that is substantially equal to an angle of reflection from the sample surface of the light provided by said first light source.

3. The system of claim 1, wherein said first light source comprises a narrowband light source comprising an ultraviolet (UV) wavelength.

4. The system of claim 1, wherein said image processor is configured to analyze said image data of the sample surface to determine if said image data includes the fingerprint by performing slope detection.

5. The system of claim 1, further comprising a second light source that illuminates a sample surface such that the sample surface produces diffuse reflection.

6. The system of claim 1, further comprising at least one scanner mechanically coupled to said optical detector for scanning said optical detector across a plurality of regions of interest on said sample surface.

7. The system of an claim 1, wherein said optical detector comprises an optical arrangement that directs and focuses incoming light onto a detector portion and wherein a numerical aperture of said optical arrangement is zero.

8. A method of detecting a latent fingerprint, comprising:

illuminating a sample surface where a latent fingerprint may be present with a first light source such that the sample surface produces specular reflection;

arranging an optical detector at a critical alignment angle relative to the first light source such that the optical detector captures the specular reflection from the sample surface and generates image data of the fingerprint using the specular reflection to generate image data of the fingerprint on the sample surface;

aligning said optical detector relative to said sample surface at an alignment angle that is substantially equal to an angle of reflection from the sample surface of the light provided by said first light source;

analyzing said generated image data of the sample surface to determine if said generated image data includes an image of the fingerprint; and

producing image data of the fingerprint responsive to a determination that said analyzed image data includes an image of the fingerprint;

wherein arranging said optical detector further comprises configuring said first light source and said optical detector such that they have substantially equal and opposite numerical apertures.

9. The method of claim 8, wherein analyzing said generated image data further comprises performing slope detection on said image data of the sample surface.

10. The method of claim 8, further comprising illuminating the sample surface with a second light source such that the sample surface produces diffuse reflection.

11. The method of claim 8, further comprising

providing broadband light and spectrally filtering said broadband light such that said sample surface is illuminated with spectrally filtered light.

12. The method of claim 11, wherein analyzing said generated image data further comprises performing slope detection on said image data of the sample surface.

13. The method of claim 11, further comprising illuminating the sample surface with a second light source such that the sample surface produces diffuse reflection.

14. The method of claim 11, wherein illuminating the sample surface further comprises illuminating with a collimated beam of light.

15. The method of claim 14, wherein illuminating with said collimated beam of light further comprises providing a narrowband beam.

16. The method of claim 8, wherein illuminating the sample surface further comprises illuminating with a collimated beam of light.

17. The method of claim 16, wherein illuminating with said collimated beam of light further comprises providing a narrowband beam.