Holographic eye imaging device
An eye tracking device for tracking an eye is described. The eye tracking device comprises: a first diffractive optical element, DOE, arranged in front of the eye, an image module, wherein the image module is configured to capture an image of the eye via the first DOE. The first DOE is adapted to direct a first portion of incident light reflected from the eye, towards the image module. The eye tracking device is characterized in that the first DOE is configured to provide a lens effect.
1. An eye tracking device for tracking an eye, comprising:
a first lens;
a first diffractive optical element (DOE), arranged adjacent to the first lens and in front of the eye;
an image module, wherein the image module is configured to capture an image of the eye via the first DOE,
wherein the first DOE is adapted to direct a first portion of incident light reflected from the eye towards the image module,
wherein the first DOE is configured to provide a lens effect; and
wherein the first DOE and the second DOE are positioned side by side, as seen from the eye, or
wherein the first DOE and the second DOE are positioned at least partly overlapping, as seen from the eye.
2. The eye tracking device according to claim 1 , wherein a focal length of the DOE is adapted to direct the first portion of incident light such as to give a sharp image of the eye in the image module.
3. The eye tracking device according to claim 1 , wherein a focal length of the DOE is an inverse of a focal length of the first lens.
4. The eye tracking device according to claim 1 , further comprising a second DOE adjacent to the first DOE, wherein the second DOE is adapted to direct a second portion of incident light reflected from the eye, towards the image module.
5. The eye tracking device according to claim 4 , wherein the second DOE is configured to provide a lens effect, wherein a focal length of the second DOE is adapted to direct the second portion of incident light such as to give a sharp image of the eye in the image module, and wherein the focal length of the second DOE is different from a focal length of the first DOE.
6. The eye tracking device according to claim 4 , wherein one or more of the first DOE and the second DOE is arranged on a support structure.
7. The eye tracking device according to claim 1 , wherein the first DOE is part of a support structure.
8. The eye tracking device according to claim 6 , wherein the support structure is transparent and comprises a polymer halide or a silver halide.
9. The eye tracking device according to claim 6 , wherein the support structure has a thickness in an interval of 2-1000 micrometers (μm), an interval of 2-200 μm, or an interval of 10-100 μm.
10. The eye tracking device according to claim 1 , wherein a viewing plane is arranged in a vicinity of or in contact with the first DOE.
11. The eye tracking device according to claim 1 , further comprising at least one illuminator configured to produce the incident light, the incident light being within a wavelength range of 650-3000 nanometers (nm).
12. The eye tracking device according to claim 1 , comprising at least one illuminator configured to produce the incident light, the incident light being within a wavelength range of 700-1500 nm.
13. The eye tracking device according to claim 1 , comprising at least one illuminator configured to produce the incident light, the incident light being within a wavelength range of 800-1000 nm.
14. The eye tracking device according to claim 11 , wherein the first portion of incident light has a first wavelength and the second portion of incident light has a second wavelength, and wherein the at least one illuminator comprises a first illuminator configured to emit light at the first wavelength and a second illuminator configured to emit light at the second wavelength, wherein the second wavelength is different from the first wavelength.
15. The eye tracking device according to claim 14 , wherein one of the first wavelength and the second wavelength is in a range 840-860 nanometers (nm), and the other of the first wavelength and the second wavelength is in a range 930-950 nm.
16. The eye tracking device according to claim 1 , wherein the first DOE is any of:
a holographic optical element comprising a volumetric reflection hologram produced by interfering two or more beams or a computer-generated hologram;
binary optics made by staircases that approximate an ideal surface relief;
a hybrid lens with combined refractive and diffractive power; or
a Fresnel zone plate.
17. The eye tracking device according to claim 1 , further comprising a control unit adapted to:
receive an image captured by the image module, and
calculate a viewing angle of the eye.
18. The eye tracking device according to claim 1 , wherein the eye tracking device comprises a head-worn device.
19. The eye tracking device according to claim 18 , wherein the head-worn device comprises one of:
glasses for eye-tracking;
an augmented reality headset, wherein a transparent viewing plane is one of (A) integrated into the DOE, (B) attached to the DOE or (C) arranged in a vicinity of the DOE; or
a virtual reality headset, comprising a viewing plane, wherein the DOE is one of (a) integrated into the viewing plane, (b) attached in front of the viewing plane or (c) arranged in front of the viewing plane.