DUAL-IMAGER BIOMETRIC SENSOR

• US 20110211055A1
• Filed: 08/26/2010
• Published: 09/01/2011
• Est. Priority Date: 08/26/2009
• Status: Active Grant

• Current Assignee: HID Global Corporation (Assa Abloy AB)
• Original Assignee: Lumidigm Incorporated (Assa Abloy AB)
• Inventors: Rowe, Robert K., Rogers, Gary, Martin, Ryan, Corcoran, Steve
• Granted Patent: US 8,872,908 B2
• Time in Patent Office: Days
• US Class Current: 348/77
• CPC Class Codes: G06V 10/143 Sensing or illuminating at different wavelengths
• CPC Class Codes: G06V 40/1312 direct reading, e.g. contactless acquisition
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence

Abstract

Embodiments disclose a two imager biometric sensor. In some embodiments, the two imagers can include a direct imager and a TIR imager. In some embodiments, multispectral light sources can be used to illuminate target tissue imaged by two imagers. In some embodiments, composite images can be created from images detected using both imagers.

Claims

1. A biometric system comprising:

first illumination means for illuminating a finger through a first facet of a multifaceted prism, wherein light from the first illumination means undergoes total internal reflectance at a second surface of the multifaceted prism prior to illuminating the object; and

first imaging means for imaging light scattered from the finger and passing though the first facet at an angle less than the critical angle and undergoing total internal reflectance at the second facet,

wherein the critical angle is defined by an interface of the first facet with an external environment and is measured relative to the normal of the first facet.

2. The system of claim 1, further comprising second imaging means for imaging light scattered from the finger and passing though the first facet at an angle greater than the critical angle.

3. The system claim 1, further comprising a light trap located proximate to the second facet such that light undergoing total internal reflectance at the first facet that passes through the second facet is substantially absorbed by the light trap.

4. The system of claim 2, further comprising a controller interfaced with the first illumination means, the first imaging means, and the second imaging means, the controller including:

instructions to illuminate the finger with the first illumination means during a single illumination session;

instructions to generate a total-internal reflectance image of the finger from light received by the second imaging means; and

instructions to generate a direct image of the finger from light received by the second imaging means.

5. The system of claim 4, wherein the controller interface further includes instructions to generate composite image of the finger using the first imaging means image and the second imaging means image of the finger.

6. The system of claim 2, wherein the first imaging means and the second imaging means are configured to receive light simultaneously.

7. The system of claim 2, wherein the first imaging means and the second imaging means are configured to acquire synchronized video streams.

8. The system of claim 2, wherein at least one of first imaging means or the second imaging means comprises a multispectral imaging means.

9. The system of claim 1, further comprising a second illumination means for illuminating the finger through the first facet of a multifaceted prism, wherein light from the second illumination means passes through the second surface of the multifaceted prism prior to illuminating the finger.

10. The system of claim 9, wherein the first illumination means and the second illumination means comprise different wavelengths.

11. A method comprising:

illuminating an object positioned at a first facet with light that undergoes total internal reflectance at a second facet;

imaging light scattered by the object that passes through the first facet at an angle less than the critical angle and undergoes total internal reflectance at the second facet; and

imaging light scattered by the object that passes through the first facet at an angle greater than the critical angle,

wherein the critical angle is defined by an interface of the first facet with an external environment and is measured relative to the normal of the first facet.

12. The method of claim 11, further comprising absorbing light at a light trap located proximate to the second facet, wherein the light undergoes total-internal-reflectance at the first facet and then passes through the second facet.

13. The method of claim 11, further comprising generating a composite image of the object using the image from light scattered by the object that passes through the first facet at the angle less than the critical angle and undergoes total internal reflectance at the second facet and the image from light scattered by the object that passes through the first facet at the angle greater than the critical angle.

14. The method of claim 11, further comprising decomposing at least one of the images into a plurality of images corresponding to different illumination conditions.

15. The method of claim 11, wherein the object comprise a barcode, a document, or money.

16. A multifaceted prism comprising:

a first facet; and

a second facet, wherein the first facet and the second facet are oriented relative to each other such that;

an object positioned at the first facet can be illuminated with light that undergoes total internal reflectance at the second facet,

a portion of light scattered by the object that passes through the first facet at an angle less than the critical angle can be imaged after undergoing total internal reflectance at the second facet, and

a portion of light scattered by the object positioned at the first facet that passes through the first facet at an angle greater than the critical angle can be imaged without interacting with the second facet,

wherein the critical angle is defined by an interface of the first facet with an external environment and is measured relative to the normal of the first facet.

17. The multifaceted prism of claim 16, further comprising:

a third facet oriented with respect to the first and second facets such the portion of light scattered by the object that passes through the first facet at an angle less than the critical angle and undergoing total internal reflectance at the second facet then passes through the third facet.

18. The multifaceted prism of claim 17, wherein the third facet is oriented substantially perpendicular to the first facet.

19. The multifaceted prism of claim 16, further comprising:

a forth facet oriented with respect to the first and second facets such that the portion of light scattered by the object positioned at the first facet that passes through the first facet at an angle greater than the critical angle passes through the fourth facet.

20. The multifaceted prism of claim 19, wherein the fourth facet is oriented at an angle greater than or equal the critical angle with respect to the first facet.

21. A system comprising:

first illumination means for illuminating an object located at a first facet of a multifaceted prism;

second illumination means for illuminating the object through a second facet and through the first facet at an angle greater than the critical angle of the first facet;

first imaging means for imaging light scattered by the object, passes through the first facet at an angle less than the critical angle, and undergoes total internal reflectance at the second facet; and

second imaging means for imaging light totally internally reflected from the first facet,

wherein the critical angle is defined by an interface of the first facet with an external environment and is measured relative to the normal of the first facet.

22. The system according to claim 21, wherein the first illumination means and the second illumination means have distinct wavelengths.

23. The system according to claim 21, wherein the second imaging means is oriented to image light totally internally reflected from the interface of the object and the first facet.

24. The system according to claim 23, wherein the first illumination means illuminates the object at an angle less than the critical angle of the first facet.

25. The system according to claim 21, wherein the first imaging means and the second imaging means are configured to acquire synchronized video streams.

26. A system comprising:

first illumination means for illuminating an object located at a first facet of a multifaceted prism;

second illumination means for illuminating the object through a second facet and through the first facet at an angle greater than the critical angle of the first facet;

first imaging means for imaging light scattered by the object, passes through the first facet at an angle less than the critical angle, and undergoes total internal reflectance at the second facet; and

second imaging means for imaging light scattered from the object at points where the object is in contact with the platen,

wherein the critical angle is defined by an interface of the first facet with an external environment and is measured relative to the normal of the first facet.

27. The system according to claim 26, wherein the second imaging means images the platen at an angle less than the critical angle.

28. The system according to claim 26, wherein the second imaging means images the platen at an elevation angle greater than the critical angle.

29. The system according to claim 26, wherein the second imaging means images the platen at an azimuth angle less than 170°

relative to the second illumination means.

30. The system according to claim 26, wherein the first illumination means and the second illumination means have distinct wavelengths.

31. A method comprising:

illuminating an object located at a first facet of a prism at an angle less than the critical angle;

illuminating the object at the first facet at an angle greater than the critical angle, wherein the light enters the prism through a second facet of the prism;

imaging light that is scattered by the object at an angle less than the critical angle relative to the first facet and totally internally reflected at the second facet using a first imaging system; and

imaging light from the first facet using a second imaging system,

wherein the critical angle is defined by an interface of the first facet with an external environment and is measured relative to the normal of the first facet.

32. The method of claim 31, wherein imaging light from the first facet using a second imaging system further comprises imaging light totally internally reflected from the first facet using the second imaging system.

33. The method of claim 31, wherein imaging light from the first facet using a second imaging system further comprises imaging light scattered by the object at object-facet interface using the second imaging system.

34. The method of claim 31, wherein illuminating the object located at the first facet of the prism at an angle less than the critical angle and illuminating the object at the first facet at the angle greater than the critical angle with light having distinct wavelengths.

35. The method of claim 31 further comprising generating a composite image of the object using the images created by a first imaging system and the second imaging system.

36. A system comprising:

a multifaceted prism having a first and second facet;

a first illumination source configured to illuminate the first facet at an angle less than the critical angle;

a second illumination source configured to illuminate the first facet at an angle greater than the critical angle, wherein light from the second illumination source enters the prism through the second facet;

a first imager configured to image light from the first facet that is totally internally reflected by the second facet; and

a second imager configured to image light from the first illumination source that is totally internally reflected from the first facet,

wherein the critical angle is defined by an interface of the first facet with an external environment and is measured relative to the normal of the first facet.

37. A system comprising:

a multifaceted prism having a first and second facet;

a first illumination source configured to illuminate the first facet at an angle less than the critical angle;

a second illumination source configured to illuminate the first facet at an angle greater than the critical angle, wherein light from the second illumination source enters the prism through the second facet;

a first imager configured to image light from the first facet that is totally internally reflected by the second facet; and

a second imager configured to image light scattered from the interface of the object and the first facet,

wherein the critical angle is defined by an interface of the first facet with an external environment and is measured relative to the normal of the first facet.

38. The system according to claim 37, wherein the second imager images light at an elevation angle less than the critical angle.

39. The system according to claim 37, wherein the second imager images light at an elevation angle greater than the critical angle.

40. The system according to claim 37, wherein the second imager images light at an azimuth angle out of phase with the second illumination source.