IRIS IMAGING USING REFLECTION FROM THE EYE

• US 20080002863A1
• Filed: 06/19/2007
• Published: 01/03/2008
• Est. Priority Date: 12/07/2004
• Status: Active Grant

• Current Assignee: Tascent, Inc.
• Original Assignee: Aoptix Technologies Incorporated
• Inventors: Northcott, Malcolm, Graves, J.
• Granted Patent: US 7,418,115 B2
• Time in Patent Office: Days
• US Class Current: 382/117
• CPC Class Codes: A61B 3/1216 for diagnostics of the iris
• CPC Class Codes: G06V 40/19 Sensors therefor

Abstract

A rapid iris acquisition, tracking, and imaging system can be used at longer standoff distances and over larger capture volumes, without the active cooperation of subjects. The captured iris images can be used for biometric identification. Light illuminates the subjects'"'"' eyes. Reflections from the eyes are used to steer a high resolution camera to the eyes in order to capture images of the irises.

Claims

1. An iris imaging system comprising:

an acquisition subsystem comprising;

a first light source for producing a first optical beam, and

first optics having a first aperture, for directing the first optical beam through the first aperture to illuminate a subject'"'"'s eye within a capture volume and further for receiving through the first aperture a retro-reflection of the first optical beam from the subject'"'"'s eye to identify an approximate location of the subject; and

an imaging subsystem comprising;

a second light source for producing a second optical beam to illuminate an iris of the subject'"'"'s eye,

second optics having a second aperture spatially separated from the first aperture, so that the second aperture does not receive the retro-reflection of the first optical beam, the second optics for producing an image of the illuminated iris, and

a camera for capturing the image of the illuminated iris with sufficient resolution for biometric identification.

2. The iris imaging system of claim 1 wherein the second light source is off-axis with respect to the camera.

3. The iris imaging system of claim 1 wherein the iris imaging system covers a capture volume of at least 1 cubic meter.

4. The iris imaging system of claim 1 wherein the iris imaging system can capture iris images at a standoff of at least 10 m.

5. The iris imaging system of claim 1 wherein the camera captures images of irises with a resolution of 100 microns or better.

6. The iris imaging system of claim 1 comprising an imaging subsystem further comprising:

a fine tracking system comprising a third light source for driving an adaptive optics loop based on an eye reflection to steer the camera to the eye.

7. The iris imaging system of claim 6 wherein the eye reflection comprises a retro-reflection from the eye that passes through the second aperture.

8. The iris imaging system of claim 6 wherein the eye reflection comprises a glint reflection from the eye that passes through the second aperture.

9. The iris imaging system of claim 6 wherein the adaptive optics loop comprises:

a deformable mirror for both steering the camera to the eye and adjusting a wavefront of the eye reflection;

a wavefront sensor for sensing the wavefront of the eye reflection; and

a controller coupled between the deformable mirror and the wavefront sensor, for adjusting the deformable mirror based on the sensed wavefront.

10. The iris imaging system of claim 1 further comprising:

software for processing the image to remove reflections from the eye.

11. An iris imaging system comprising:

an acquisition subsystem comprising;

a first light source for producing a first optical beam having a first wavelength, and

a first camera sensitive to the first wavelength, for receiving a reflection of the first optical beam from a subject'"'"'s eye within a capture volume to identify an approximate location of the subject;

an imaging subsystem comprising;

a second light source for producing a second optical beam having a second wavelength to illuminate an iris of the subject'"'"'s eye, and

a second camera sensitive to the second wavelength, for capturing an image of the illuminated iris with sufficient resolution for biometric identification; and

a first dichroic or other wavelength selective element positioned to direct light of the first wavelength to the acquisition subsystem and direct light of the second wavelength to the imaging subsystem.

12. The iris imaging system of claim 11 wherein the second camera is a monochromatic camera sensitive to the second wavelength.

13. The iris imaging system of claim 11 wherein the first and second wavelengths are not visible to humans.

14. The iris imaging system of claim 11 wherein the second light source is off-axis with respect to the second camera.

15. The iris imaging system of claim 11 comprising an imaging subsystem further comprising:

a fine tracking subsystem comprising a third light source having a third wavelength, for driving an adaptive optics loop based on an eye reflection to steer the second camera.

16. The iris imaging system of claim 15 wherein the adaptive optics loop comprises:

a deformable mirror for both steering the second camera to the eyes and adjusting a wavefront of the eye reflection;

a wavefront sensor for sensing the wavefront of the eye reflection; and

a controller coupled between the deformable mirror and the wavefront sensor, for adjusting the deformable mirror based on the sensed wavefront.

17. The iris imaging system of claim 16 further comprising:

a second dichroic element positioned to direct light of the third wavelength to the wavefront sensor and direct light of the second wavelength to the second camera.

18. The iris imaging system of claim 11 further comprising:

software for processing the image to remove reflections from the eye.

19. An iris imaging system comprising:

an acquisition subsystem comprising;

a first light source for producing a first optical beam, and

a first camera for receiving a retro-reflection of the first optical beam from a subject'"'"'s eye within a capture volume to identify an approximate location of the subject;

an imaging subsystem comprising;

a second light source for producing a second optical beam to illuminate an iris of the subject'"'"'s eye, and

a second camera for capturing an image of the illuminated iris with sufficient resolution for biometric identification; and

a fine tracking subsystem comprising;

a third light source for inducing an eye reflection for driving an adaptive optics loop; and

a wavefront sensor for sensing the wavefront of the eye reflection,

wherein the acquisition subsystem, the imaging subsystem, and the fine tracking subsystem are activated in a pattern in time.

20. The iris imaging system of claim 19 wherein the eye reflection comprises a retro-reflection from the eye.

21. The iris imaging system of claim 19 wherein the eye reflection comprises a glint reflection from the eye.

22. The iris imaging system of claim 19 wherein no two of the first light, the second light and the third light are active at a single point in time.

23. The iris imaging system of claim 19 wherein the pattern comprises time periods of unequal lengths.

24. The iris imaging system of claim 19 wherein the imaging subsystem is active when the acquisition subsystem and fine tracking subsystem are not active.

25. An iris imaging system comprising:

an acquisition subsystem comprising;

a first light source for producing a first polarized optical beam, and

a first camera for receiving a glint reflection of the first optical beam from a subject'"'"'s eye within a capture volume to identify an approximate location of the subject within a capture volume, the glint reflection preserving the polarization of the first optical beam;

an imaging subsystem comprising;

a second light source for producing a second optical beam to illuminate an iris of the subject'"'"'s eye, and

a second camera for capturing an image of the illuminated iris with sufficient resolution for biometric identification; and

a polarization beamsplitter positioned to direct the polarized glint reflection away from the second camera and toward the first camera.

26. An iris imaging system comprising:

an acquisition subsystem comprising;

a first light source for producing a first optical beam, and

a first camera for receiving a retro-reflection of the first optical beam from a subject'"'"'s eye within a capture volume to identify an approximate location of the subject within a capture volume;

an imaging subsystem comprising;

a second light source for producing a second optical beam to illuminate an iris of the subject'"'"'s eye,

a second camera for capturing an image of the illuminated iris with sufficient resolution for biometric identification, and

a fine tracking subsystem comprising;

a third light source for producing a polarized third optical beam, the polarized optical beam for inducing a glint reflection from the subject'"'"'s eye for driving an adaptive optics loop, the glint reflection preserving the polarization of the third optical beam;

a deformable mirror for both steering the camera to the eye and adjusting a wavefront of the glint reflection,

a wavefront sensor for sensing the wavefront of the glint reflection, and

a controller coupled between the deformable mirror and the wavefront sensor, for adjusting the deformable mirror based on the sensed wavefront; and

a polarization beamsplitter positioned between the deformable mirror and the wavefront sensor to direct the polarized glint reflection toward the wavefront sensor and away from the second camera.

27. An iris imaging system comprising:

an acquisition subsystem comprising;

a first light source for producing a first optical beam having a first modulation, for inducing a first reflection from a subject'"'"'s eye that maintains the first modulation, and

a first camera for receiving the first reflection of the first optical beam from a subject'"'"'s eye within a capture volume to identify an approximate location of the subject within a capture volume, the first reflection preserving the modulation of the first optical beam; and

an imaging subsystem comprising;

a second light source for producing a second optical beam to illuminate an iris of the subject'"'"'s eye,

a second camera for capturing an image of the illuminated iris with sufficient resolution for biometric identification, and

a fine tracking system comprising;

a third light source for producing a third optical beam having a second modulation, for inducing a second reflection from a subject'"'"'s eye for driving an adaptive optics loop, the second reflection preserving the second modulation, and

a wavefront sensor for sensing a wavefront of the first and second reflections and separating a contribution of the first light source from the third light source based on the first and second modulations.

28. The iris imaging system of claim 27 wherein the first modulation is distinct from the second modulation.

29. The iris imaging system of claim 27 wherein the first and second reflections are retro-reflections from the subject'"'"'s eye.

30. The iris imaging system of claim 27 further comprising:

software for processing the image to remove reflections from the eye.

31. The iris imaging system of claim 27, wherein the second camera captures at least two images of the illuminated iris at different illumination levels, and wherein a first of the images is subtracted from a second of the images to identify reflections from a cornea of the subject'"'"'s eye.

32. A method of imaging an iris of an eye, comprising:

directing a first optical beam through a first aperture to illuminate a subject'"'"'s eye within a capture volume;

receiving through the first aperture a retro-reflection of the first optical beam from the subject'"'"'s eye to identify an approximate location of the subject;

illuminating an iris of the subject'"'"'s eye; and

producing an image of the illuminated iris through a second aperture spatially separated from the first aperture, so that the second aperture does not receive the retro-reflection of the first optical beam, the image having sufficient resolution for biometric identification.

33. A method of imaging an iris of an eye, comprising:

illuminating a subject'"'"'s eye with a first optical beam having a first wavelength;

directing reflected light of the first wavelength to a first camera sensitive to the first wavelength to identify an approximate location of the subject;

illuminating an iris of the subject'"'"'s eye with a second optical beam having a second wavelength;

directing reflected light of the second wavelength to a second camera sensitive to the second wavelength to capture an image of the illuminated iris with sufficient resolution for biometric identification.

34. A method of imaging an iris of an eye, comprising:

activating an acquisition subsystem comprising a first light source and a first camera for receiving a retro-reflection of a first optical beam from a subject'"'"'s eye within a capture volume to identify an approximate location of the subject;

activating an imaging subsystem comprising a second light source and a second camera for capturing an image of an illuminated iris of the subject'"'"'s eye with sufficient resolution for biometric identification;

activating a fine tracking subsystem comprising a third light source for inducing an eye reflection for driving an adaptive optics loop and a wavefront sensor for sensing the wavefront of the eye reflection,

wherein the acquisition subsystem, the imaging subsystem, and the fine tracking subsystem are activated in a pattern in time.

35. A method of imaging an iris of an eye, comprising:

producing a polarized optical beam for inducing a glint reflection from the subject'"'"'s eye, the glint reflection preserving the polarization of the polarized optical beam;

directing the polarized glint reflection toward a wavefront sensor and away from an imaging camera;

driving the wavefront sensor of an adaptive optics loop with the glint reflection; and

capturing an image of an iris of the subject'"'"'s eye with the imaging camera with sufficient resolution for biometric identification.

36. A method of imaging an iris of an eye, comprising:

illuminating a subject'"'"'s eye with a first optical beam having a first modulation;

receiving a first reflection of the first optical beam to identify an approximate location of the subject within a capture volume, the first reflection preserving the first modulation;

illuminating an iris of the subject'"'"'s eye with a second optical beam;

capturing an image of the illuminated iris with sufficient resolution for biometric identification;

illuminating the subject'"'"'s eye with a third optical beam having a second modulation;

receiving a second reflection of the second optical beam from a subject'"'"'s eye, the second reflection preserving the second modulation, the second reflection for driving a wavefront sensor; and

sensing a wavefront of the first and second reflections; and

separating a contribution of the first optical beam from the third optical beam based on the first and second modulations.

37. The method of claim 36, wherein capturing an image of the illuminated iris comprises capturing at least two images of the illuminated iris at different illumination levels, and wherein a first of the images is subtracted from a second of the images to identify reflections from a cornea of the subject'"'"'s eye.