Latent fingerprint detectors and fingerprint scanners therefrom

• US 9,188,546 B2
• Filed: 04/24/2014
• Issued: 11/17/2015
• 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 Jr.
• Primary Examiner(s): DULANEY, KATHLEEN YUAN
• Application Number:
  US14/260,549
• Publication Number:
  US 20140254894A1
• Time in Patent Office: 572 Days
• Field of Search: 382/124, 382/116, 382/312, 356/71
• US Class Current: 1/1
• 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 surface contaminant detection system, comprising:

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

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 essentially only the specular reflection to generate image data of the sample surface;

wherein said first light source and said optical detector comprise substantially equal and opposite numerical apertures to create geometric filtering to discriminate against diffuse reflection.

2. The system according to claim 1, wherein the 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 according to claim 1, wherein said first light source comprises a narrowband light source comprising an ultraviolet (UV) wavelength.

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

5. The system according to 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.

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

7. The system according to claim 1, wherein a surface contaminant comprises a fracture in the sample surface or a physical defect in the sample surface.

8. The system according to claim 1, further comprising an image processor configured to:

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

produce image data of the surface contaminant responsive to a determination that said analyzed image data includes the surface contaminant.

9. The system according to claim 1, wherein an illumination from the first light is provided as collimated or narrow to provide increased specular reflection.

10. A surface contaminant detection system, comprising:

a light source alignment portion configured to align a light source at an illumination angle relative to a sample surface such that said light source illuminates said sample surface so that the sample surface produces specular reflection; and

a specular reflection discriminator configured to direct 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 such that the directed specular reflection does not saturate the optical detector; and

the optical detector configured to capture the specular reflection from the sample surface and generates image data using essentially only the specular reflection to generate image data of the sample surface;

wherein said light source and said optical detector comprise substantially equal and opposite numerical apertures to create geometric filtering to discriminate against diffuse reflection.

11. The system according to claim 10, the system 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, where said scanner is configured to maintain a critical alignment angle during scanning.

12. The system according to claim 10, wherein the surface contaminant comprises a fracture in the sample surface or a physical defect in the sample surface.

13. The system according to claim 10, further comprising an image processor configured to:

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

produce image data of the surface contaminant responsive to a determination that said analyzed image data includes the surface contaminant.

14. The method according to claim 13, further comprising producing image data of the contaminated area responsive to a determination that said analyzed image data includes an image of the surface contaminant.

15. The system according to claim 10, wherein an illumination from the first light is provided as collimated or narrow to provide increased specular reflection.