Topographical object detection system

• US 5,986,746 A
• Filed: 03/26/1997
• Issued: 11/16/1999
• Est. Priority Date: 02/18/1994
• Status: Expired due to Fees

• Current Assignee: Stanley H. Kremen
• Original Assignee: Imedge Technology Incorporated
• Inventors: Coleman, Zane, Metz, Michael, Flatow, Carl, Phillips, Nicholas J.
• Primary Examiner(s): Rosenberger, Richard A.
• Application Number:
  US08/823,754
• Time in Patent Office: 965 Days
• Field of Search: 356/71, 382/124, 382/126, 382/127, 382/125
• US Class Current: 356/71
• CPC Class Codes: A61B 5/1172 using fingerprinting
• CPC Class Codes: G06K 7/10663 using hologram
• CPC Class Codes: G06K 7/10702 Particularities of propagating elements, e.g. lenses, mirrors G06K7/10831 takes precedence
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence
• CPC Class Codes: G07C 9/37 using biometric data, e.g. fingerprints, iris scans or voice recognition

Abstract

A compact system for producing high contrast and high resolution images of a topographical surface associated with an object. The system utilizes a novel holographic optical element to produce images of topographical surfaces differentiating between ridges and valleys, and providing image details of artifacts. The system of the present invention can be realized in the form of a hand-held instrument for use in in vivo imaging of fingerprint, skin tissue and the like.

Claims

1. A device for producing an image of a topographic surface having ridges and valleys, said device comprising:

light producing means for producing light rays;

a light transmitting substrate capable of transmitting the light produced by said light producing means;

a topographic surface illuminating region for physical placement of an object having a topographical surface;

an image detection means for detecting an image of said topographical surface;

an optical element affixed to a portion of said light transmitting substrate and being disposed between said topographical surface illuminating region and said image detection means, said optical element embodying a light diffracting grating;

wherein said topographic surface illuminating region and said optical element are each disposed substantially along a common optical axis; and

wherein during the operation of said device,

(1) light rays produced by said light producing means, propagate within said light transmitting substrate towards and into said optical element and are diffracted by said light diffracting grating,

(2) diffracted light rays produced by said light diffracting grating, propagate directly towards said topographical surface illuminating region and fall incident upon and are intensity modulated by the ridges and valleys of said topographical surface, and

(3) at least a portion of the intensity modulated light rays produced from said ridges and valleys of said topographical surface propagate back at an angle less than the critical angle of said light transmitting substrate through said light transmitting substrate and said optical element and fall incident upon said image detection means, whereupon an image of said topographical surface is detected.

2. The device of claim 1, wherein said light transmitting substrate has an upper surface in which said topographical surface illuminating region is disposed, and a lower surface arranged opposite said upper surface.

3. The device of claim 2, wherein said light diffracting grating comprises light diffracting structures that are slanted with respect to the upper and lower surfaces of said light transmitting substrate.

4. The device of claim 3, wherein said optical element is affixed to the lower surface of said light transmitting substrate.

5. The device of claim 4, wherein said light diffracting grating is a hologram containing a slanted fringe structure.

6. The device of claim 5, wherein said hologram is a volume hologram.

7. The device of claim 6, wherein said volume hologram is of the reflection type.

8. The device of claim 7, in which the index of refraction of said hologram closely matches that of said light transmitting substrate.

9. The device of claim 3, wherein said light transmitting substrate, said optical element and said light producing means are contained within a compact housing having an access aperture through which said topographical surface can be brought into physical contact with said light transmitting substrate, within said topographical surface illuminating region.

10. The device of claim 1, wherein said optical element is affixed to the upper surface of said light transmitting substrate, between said topographical surface illuminating region and said light transmitting substrate.

11. The device of claim 10, wherein said light diffracting grating is a hologram containing a slanted fringe structure.

12. The device of claim 11, wherein said hologram is a volume hologram.

13. The device of claim 12, wherein said volume hologram is of the transmission type.

14. The device of claim 10, which further comprises a light transmitting superstrate affixed to said upper surface of said optical element, and in which said topographical surface illuminating region is disposed.

15. The device of claim 14, wherein said light transmitting substrate, said optical element, said superstrate and said light producing means are contained within a compact housing having an access aperture through which said topographical surface can be placed in physical contact with said light transmitting superstrate, within said topographical surface illuminating region.

16. The device of claim 1, wherein said image detection means is an electro-optical image detector.

17. The device of claim 16, wherein said electro-optical image detector is an image detection array.

18. The device of claim 1, wherein said light producing source produces substantially monochromatic light.

19. The device of claim 1, wherein said light producing source comprises a white light source for producing white light.

20. The device of claim 19, which further comprises a narrow wavelength bandpass filter disposed between said white light source and said light transmitting substrate.

21. The device of claim 1, which further comprises a narrow wavelength bandpass filter disposed substantially along said optical axis and between said optical element and said image detection means.

22. The device of claim 1, which further comprises an image transfer means disposed between said image detection means and said optical element.

23. The device of claim 22, wherein said image transfer means is a structure selected from the group consisting of a lens system, a microchannel plate, a fiber optic array, and a micro-lens array.

24. The device of claim 1, in combination with an image storage means for storing images produced by said image detection means.

25. The combination of claim 24, which further comprises an image analyzer and an image database.

26. The device of claim 1, which further includes electronic circuitry for interfacing said image detection means with a computer-based system.

27. The device of claim 1, wherein said light producing means is a structure selected from the group consisting of a monochromatic light source, a small filament incandescent lamp, and a light emitting diode.

28. The device of claim 1, wherein said light diffracting grating produces converging light rays when said light rays strike said light diffracting grating.

29. The device of claim 1, wherein said light diffracting grating produces substantially collimated light rays when said light beam strikes said light diffracting grating.

30. The device of claim 1, wherein said light diffracting grating produces diverging light rays when said light rays strike said light diffracting grating.

31. The device of claim 1, wherein the indices of refraction of said light transmitting substrate and said optical element are matched to optimize light transmission efficiency therebetween.

32. The device of claim 1, wherein light rays produced from said light producing means strike said light diffracting -grating such that the first diffraction order of said diffracted light travels at an angle with respect to said optical axis, which is less than the critical angle for said light transmitting substrate and/or said optical element.

33. The device of claim 1, wherein said topographical surface illuminating region is associated with a portion of said light transmitting substrate about said optical axis.

34. The device of claim 1, wherein said topographical surface illuminating region is associated with a portion of said optical element about said optical axis.

35. The device of claim 1, which further comprises a light transmitting substrate operably associated with said optical element.

36. The device of claim 1, which further comprises a PCMCIA-type housing containing said light producing means, said light transmitting substrate, said optical element, and said image detection means.

37. The device of claim 1, wherein said topographical surface illuminating region, said optical element and said image detection means are each disposed substantially along said common optical axis.

38. The device of claim 37, wherein said detected image includes information corresponding to said ridges and valleys of said topographical surface.

39. The device of claim 38, wherein said topographical surface is a fingerprint.

40. The device of claim 36, wherein said topographical surface is a sample of skin tissue.

41. The device of claim 1, wherein said diffracted light rays propagate toward said topographical surface illuminating region at an angle less than the critical angle of said light transmitting substrate.

42. The device of claim 41, wherein said portion of the intensity modulated light rays propagate back through said light transmitting substrate and said optical element at an angle less than the critical angles of said light transmitting element and said optical element.

43. The device of claim 42, in which the light rays produced by said topographical surface travel along a second optical axis different from said common optical axis.

44. The device of claim 43, wherein said second optical axis is offset from the axis of the peak Bragg angle for said light diffracting grating.

45. The device of claim 43, in which the optical axis of said image detection means is along said second optical axis.

46. The device of claim 1, further comprising a second light diffracting grating secured to the upper surface of said light transmitting substrate and spaced thereon from said first mentioned light diffracting grating, said light producing means being positioned to transmit light through said light transmitting surface to said second light diffracting grating, wherein light diffracted from said second light diffracting grating propagates within said light transmitting substrate toward said first light diffracting grating at an angle greater than the critical angle for said light transmitting substrate.

47. The device of claim 46, in which the index of refraction of said second light diffracting grating closely matches that of said light transmitting substrate.

48. The device of claim 1, further comprising a second light diffracting grating secured to the underside of said light transmitting substrate and spaced thereon from said first mentioned light diffracting grating, said light producing means being positioned beneath and in optical communication with said second light diffracting grating, wherein light diffracted from said second light diffracting grating propagates within said light transmitting substrate at an angle greater than the critical angle of said light transmitting substrate to pass into and illuminate said first-mentioned light diffraction grating.

49. The device of claim 1, in which said light diffracting grating is operatively secured to the underside of said light transmitting surface, and said image detection means is operatively secured to the underside of said light diffracting grating.

50. The device of claim 49, further including a narrow bandpass optical filter interposed and operatively secured to said light diffracting grating and said image detection means.

51. The device of claim 1, in which said light diffracting grating is operatively secured to the upper surface of said light transmitting substrate, and said image detecting means is operatively secured to the underside of said light transmitting substrate.

52. The device of claim 1, further comprising first polarizing means adjacent the underside of said light diffracting grating, said image detection means being operatively secured to the underside of said first polarizing means.

53. The device of claim 52, further comprising second polarizing means optically interposed intermediate said light producing means and said light transmitting substrate.

54. The device of claim 53, in which said first polarizing means is a P- polarizing filter and said second polarizing means is an S-polarizing filter.

55. The device of claim 54, further comprising a phase-retardation plate operatively secured to the upper surface of said light transmitting substrate.

56. The device of claim 1, further comprising narrow band pass filter means interposed intermediate said light producing means and said light diffraction grating for matching the wavelength of the Bragg condition for said light diffracting grating.

57. The device of claim 1, wherein light rays returning from the object are diffracted by said light diffracting grating at an angle that meets the Bragg condition, are diffracted by said light diffracting grating at an angle less than the critical angle of said light transmitting substrate, and pass out of said light transmitting substrate to said image detection means.

58. A hand-supportable instrument for producing an image of a topographical surface, comprising:

a hand-supportable housing; and

said device of claim 1 disposed within said hand-supportable housing.

59. The hand-supportable instrument of claim 58, wherein said hand-supportable housing comprises a head portion having an image sensing window, and a handle portion supportable within the hand of a user.

60. The hand-supportable instrument of claim 59, wherein said device is disposed within said head portion, and said topographical surface illuminating region of said device is aligned with said image sensing window to allow the topographical surface of said object to be imaged through said image sensing window.

61. The hand-supportable instrument of claim 60, which further comprise a cordless RF-based communication interface between said device and a base unit operably connectable to a host computer system.

62. The hand-supportable instrument of claim 61, which further comprise a rechargeable power supply disposed within said hand-supportable housing and a battery recharger disposed within said base unit, and wherein said base unit has a recess for receiving and supporting said hand-supportable housing so as to allow recharging of said rechargeable battery supply while supported therein.

63. A topographical image detector comprising a light source, an object supporting light transmitting layer, a volume hologram, an index discontinuation layer interposed between said object supporting layer and said hologram, a light transmitting substrate affixed to said hologram, and image detecting means in optical communication with said light transmitting substrate, whereinlight from said light source passes through said light transmitting substrate and said volume hologram and is then reflected at the interface of said hologram and said index discontinuity layer and is then reflected back into said volume hologram at an angle satisfying the Bragg condition;

2) said hologram diffracts the light which passes through said index discontinuity layer and said object supporting layer to illuminate the object supported therein, and

3) reflected light modulated by the surface pattern of the object is then reflected back through said index discontinuously layer, said hologram, and said light transmitting medium to said image detection means.

64. The device of claim 63, therein said index discontinuity layer comprises air or a partial index matching medium.

65. The device of claim 63, further comprising a band-pass filter optically interposed between said light transmitting substrate and said image detection means.