Liveness sensor

• US 20060002597A1
• Filed: 07/08/2005
• Published: 01/05/2006
• Est. Priority Date: 04/04/2003
• Status: Active Grant

• Current Assignee: HID Global Corporation (Assa Abloy AB)
• Original Assignee: Lumidigm Incorporated (Assa Abloy AB)
• Inventors: Rowe, Robert K.
• Granted Patent: US 7,440,597 B2
• Time in Patent Office: Days
• US Class Current: 382/124
• CPC Class Codes: A61B 5/1171 based on the shapes or appearances of their bodies or parts thereof
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/14558 by polarisation
• CPC Class Codes: B60K 28/06 responsive to incapacity of driver
• CPC Class Codes: B60R 25/252 Fingerprint recognition
• CPC Class Codes: B60W 2540/22 Psychological state; Stress level or workload
• CPC Class Codes: B60W 2540/221 Physiology, e.g. weight, heartbeat, health or special needs
• CPC Class Codes: B60W 2540/24 Drug level, e.g. alcohol
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence
• CPC Class Codes: G06V 40/1341 Sensing with light passing through the finger
• CPC Class Codes: G06V 40/14 Vascular patterns

Abstract

Methods and systems are provided for biometric sensing. An illumination subsystem provides light at discrete wavelengths to a skin site of an individual. A detection subsystem receives light scattered from the skin site. A computational unit is interfaced with the detection system. The computational unit has instructions for deriving a spatially distributed multispectral image from the received light at the discrete wavelengths. The computational unit also has instructions for comparing the derived multispectral image with a database of multispectral images to identify the individual.

Claims

1. A sensor system comprising:

an illumination subsystem disposed to provide light at a plurality of discrete wavelengths to a sample;

a detection subsystem disposed to receive light scattered within tissue of the sample; and

a computational unit interfaced with the detection subsystem and having;

instructions for deriving multispectral characteristics of the received light at the plurality of discrete wavelengths; and

instructions for determining a liveness state of the tissue from the derived multispectral characteristics.

2. The sensor system recited in claim 1 wherein the illumination subsystem comprises:

a light source that provides the light at the plurality of discrete wavelengths; and

illumination optics to direct the light to the skin site.

3. The sensor system recited in claim 2 wherein the light source comprises a plurality of quasimonochromatic light sources.

4. The sensor system recited in claim 3 wherein at least one of the quasimonochromatic light sources comprises an LED.

5. The sensor system recited in claim 3 wherein at least one of the quasimonochromatic light sources comprises a laser diode.

6. The sensor system recited in claim 1 wherein the illumination subsystem comprises:

a broadband light source; and

a filter disposed to filter light emitted from the broadband light source.

7. The sensor system recited in claim 6 wherein the broadband light source comprises an incandescent bulb.

8. The sensor system recited in claim 6 wherein the broadband light source comprises a glowbar.

9. The sensor system recited in claim 6 wherein the filter comprises a continuously variable filter.

10. The sensor system recited in claim 1 wherein the instructions for determining the liveness state of the tissue comprise:

instructions for pixelating a spatial distribution of the derived multispectral characteristics; and

instructions for performing a multivariate factor analysis on a matrix having entries in a first dimension corresponding to a pixel of a pixelated spatial distribution and having entries in a second dimension corresponding to one of the plurality of discrete wavelengths.

11. A method for determining a liveness state of a sample, the method comprising:

illuminating the sample with light at a plurality of discrete wavelengths;

receiving light scattered within tissue of the sample;

deriving multispectral characteristics of the received light at the plurality of discrete wavelengths; and

determining a liveness state of the tissue from the derived multispectral characteristics.

12. The method recited in claim 11 wherein illuminating the skin site comprises;

providing light at the plurality of discrete wavelengths; and

directing the light to the skin site.

13. The method recited in claim 12 wherein providing the light at the plurality of discrete wavelengths comprises generating the light as a plurality of quasimonochromatic beams.

14. The method recited in claim 12 wherein providing the light at the plurality of discrete wavelengths comprises:

generating a broadband beam of light; and

filtering the broadband beam.

15. The method recited in claim 14 wherein receiving the light comprises:

angularly separating separate wavelength components of the received light; and

directing the angularly separated wavelength components to a light detector.

16. The method recited in claim 11 wherein illuminating the skin site with the light comprises illuminating the skin site with the plurality of discrete wavelengths substantially simultaneously and with an identifiable encoding.

17. The method recited in claim 11 wherein illuminating the skin site with the light comprises providing the plurality of discrete wavelengths sequentially.

18. The method recited in claim 11 wherein the skin site comprises a volar surface of a fingertip.

19. The method recited in claim 11 wherein the skin site comprises a volar surface of a hand.

20. The method recited in claim 11 wherein determining the liveness state of the tissue comprises:

pixelating spatial distributions of the derived multispectral characteristics; and

performing a multivariate factor analysis on a matrix having entries in a first dimension corresponding to a pixel of a pixelated spatial distribution and having entries in a second dimension corresponding to one of the plurality of discrete wavelengths.