Biometric imaging system and method of determining properties of a biometric object using the biometric imaging system

1. A biometric imaging system comprising:

a display panel comprising a plurality of display pixels configured to emit visible light and controllable to form an image in the display, and a plurality of non-visible light emitting elements configured to emit linearly polarized non-visible light;

a camera configured to receive polarized non-visible light having an orientation which is rotated with respect to the emitted linearly polarized light; and

control circuitry configured to:

activate the plurality of non-visible light emitting elements to emit linearly polarized light towards a biometric object, the biometric object being an eye; and

control the camera to capture an image based on light reflected by the biometric object having a polarization which is rotated with respect to the emitted linearly polarized light; and

determine if the biometric object belongs to a real person based on birefringent properties of the biometric object observed in the captured image.

2. The biometric imaging system according to claim 1 , wherein the camera is configured to receive polarized non-visible light having a 90° rotation with respect to the emitted linearly polarized light.

3. The biometric imaging system according to claim 1 , wherein each of the plurality of non-visible light emitting elements comprises a first linearly polarizing filter.

4. The biometric imaging system according to claim 3 , wherein the camera comprises a second linearly polarizing filter having a 90° rotation with respect to the first linearly polarizing filter.

5. The biometric imaging system according to claim 3 , wherein the first and/or the second polarizing filter is a polarizing coating layer.

6. The biometric imaging system according to claim 1 , further comprising a polarizing layer located between the plurality of display pixels and a cover glass of the display panel.

7. The biometric imaging system according to claim 6 , wherein the polarizing layer comprises openings at locations of a subset of display pixels configured to emit non-visible light.

8. The biometric imaging system according to claim 1 , wherein at least a subset of the plurality of display pixels each comprises a non-visible light emitting element.

9. The biometric imaging system according to claim 1 , wherein at least a subset of the plurality of display pixels comprises a red, green and blue light emitting element, and a non-visible light emitting element.

10. The biometric imaging system according to claim 1 , wherein a first subset of the plurality of display pixels consists of a non-visible light emitting element, and wherein a second subset of the plurality of display pixels consists of a red, green and blue light emitting element.

11. The biometric imaging system according to claim 1 , wherein the non-visible light emitting elements are infrared light emitting elements or ultraviolet light emitting elements.

12. An electronic device comprising a biometric imaging system according to claim 1 .

13. A method of determining properties of a biometric object using a biometric imaging system, the system comprising: a display panel comprising: a plurality of display pixels configured to emit visible light and controllable to form an image in the display; and a plurality of non-visible light emitting elements configured to emit linearly polarized non-visible light; and a camera configured to receive polarized non-visible light having a rotation with respect to the emitted linearly polarized light, the method comprising:

activating the plurality of non-visible light emitting elements to emit linearly polarized light towards a biometric object, the biometric object being an eye;

controlling the camera to capture an image based on light reflected by the biometric object having a polarization which is rotated with respect to the emitted linearly polarized light;

determining birefringent properties of the biometric object based on the captured image; and

determining if the biometric object belongs to a real person based on the birefringent properties of the biometric object.

14. The method according to claim 13 , further comprising identifying a refraction pattern of the biometric object in the captured image;

comparing the refraction pattern with a group of predetermined refraction patterns; and

if the identified refraction pattern corresponds to a refraction pattern of the group of predetermined refraction patterns, determine that the biometric object belongs to a real person.

15. The method according to claim 14 , further comprising identifying a refraction pattern located in the cornea of the eye.

16. The method according to claim 15 , wherein the refraction pattern is an isogyre.

17. The method according to claim 16 , further comprising capturing a second image of the biometric object based on all light reflected from the biometric object; and

comparing the second image with the captured image based on light reflected by the biometric object having a polarization which is rotated 90° with respect to the emitted linearly polarized light.

18. The method according to claim 17 , further comprising determining that the biometric object belongs to a real person if a pattern is observed in the image based on polarized light which is not observed in the second image.