Extended field of view in near-eye display using wide-spectrum imager

• US 9,671,615 B1
• Filed: 12/01/2015
• Issued: 06/06/2017
• Est. Priority Date: 12/01/2015
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Vallius, Tuomas, Pietilae, Pasi Petteri
• Primary Examiner(s): McDowell, Jr., Maurice L
• Application Number:
  US14/955,273
• Publication Number:
  US 20170153460A1
• Time in Patent Office: 553 Days
• Field of Search: None
• CPC Class Codes: G02B 2027/0112 comprising device for genereting colour display
• CPC Class Codes: G02B 2027/0123 comprising devices increasing the field of view
• CPC Class Codes: G02B 2027/014 comprising information/image processing systems
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/4205 having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
• CPC Class Codes: G02B 27/4233 having a diffractive element [DOE] contributing to a non-imaging application diffusers having a diffractive element G02B5/0252; filters having a diffractive element G02B5/203; systems for controlling the direction of light having diffractive elements G02B26/0808; scanning systems having diffractive elements G02B26/106; beam shaping systems using diffractive optical elements G02B27/0944; beam splitting or combining systems operating by diffraction G02B27/1086
• CPC Class Codes: G06T 19/006 Mixed reality object pose determination, tracking or camera calibration for mixed reality G06T7/00

Abstract

In a near-eye optical display system comprising a waveguide and diffractive optical elements (DOEs) configured for in-coupling, exit pupil expansion, and out-coupling, a wide-spectrum imager generates imaging light that is in-coupled to the system with an input pupil having an extended field of view (FOV). Wide-spectrum imaging light impinges on the in-coupling DOE over a range of incidence angles. As chromatic dispersion in the in-coupling DOE causes different wavelengths to propagate with different angles, for a given input pupil incidence angle, at least a portion of the imaging light spectrum meets a critical angle condition that enables propagation with total internal reflection (TIR) in the waveguide without leakage to the outside. Thus, different parts of the imaging light spectrum can be used for different regions of the FOV.

Claims

1. A display system, comprising:

an imager configured to generate imaging light using a variable spectrum across a field of view (FOV) of an input pupil;

a substrate of optical material that includes a waveguide;

an in-coupling diffractive optical element (DOE) disposed on the substrate, the in-coupling DOE having an input surface configured to receive incident imaging light over the input pupil; and

an out-coupling DOE disposed on the substrate, the out-coupling DOE having an output surface and configured for pupil expansion of the imaging light in one direction, and further configured to out-couple, as an output display from the output surface, the imaging light with expanded exit pupil relative to the input pupil,

wherein the in-coupling DOE is configured to spread the spectrum of imaging light over the input pupil FOV so that at least a part of the spectrum propagates in total internal reflection in the waveguide for each portion of the FOV.

2. The display system of claim 1 further comprising an intermediate DOE disposed on the substrate and located downstream from the in-coupling DOE and upstream from the out-coupling DOE, the intermediate DOE configured for pupil expansion in a different direction from the out-coupling DOE.

3. The display system of claim 1 in which a short portion of the spectrum fills a first portion of the input pupil FOV and a long portion of the spectrum fills a second portion of the input pupil FOV.

4. The display system of claim 1 in which chromatic dispersion in the in-coupling DOE causes spectral propagation angles of the imaging light in the waveguide to vary with wavelength, and chromatic dispersion in the out-coupling DOE causes the out-coupled imaging light to have parallel angles with respect to the incident imaging light.

5. The display system of claim 1 in which the imager comprises a wide-spectrum imager configured to provide illumination over a wavelength bandwidth of about 40 nm.

6. An electronic device supporting a mixed reality experience including elements from a virtual world and elements from a real world, comprising:

a data processing unit;

an optical engine operatively connected to the data processing unit and configured to receive image data from the data processing unit;

a wide-spectrum imager operatively connected to the optical engine to form images using a predetermined optical spectrum based on the image data and to generate imaging light that incorporates the images; and

an exit pupil expander, responsive to the imaging light received over an input pupil having a field of view (FOV), comprising a structure on which multiple diffractive optical elements (DOEs) are disposed,

wherein the exit pupil expander is configured to provide one or more out-coupled optical beams, using one or more of the DOEs, as a near-eye display with an expanded exit pupil relative to the input pupil, and

wherein different parts of the spectrum of the imaging light are utilized for different regions of the FOV of the input pupil.

7. The electronic device of claim 6 in which the wide-spectrum imager is configured so that a particular wavelength of the imaging light that is capable of propagation within the exit pupil expander in total internal reflection at a given angle of the FOV is utilized for the region of the FOV that includes the given angle.

8. The electronic device of claim 6 in which the exit pupil expander provides pupil expansion in two directions.

9. The electronic device of claim 6 in which the wide-spectrum imager includes one of light emitting diode, liquid crystal on silicon device, organic light emitting diode array, or micro-electro mechanical system device.

10. The electronic device of claim 6 in which the wide-spectrum imager comprises a micro-display operating in one of transmission, reflection, or emission.

11. The electronic device of claim 6 as implemented in a head mounted display device or portable electronic device.

12. The electronic device of claim 6 in which the wide-spectrum imager includes or incorporates an illumination unit.

13. The electronic device of claim 6 in which the wide-spectrum imager varies the optical spectrum over the FOV.

14. The electronic device of claim 6 in which the wide-spectrum imager is configured so that at least a portion of the spectrum is propagated in total internal reflection for each portion of the FOV.

15. A method, comprising:

operating a wide-spectrum imager configured to produce imaging light over a predetermined range of wavelengths;

receiving the imaging light over an input pupil having a field of view (FOV) at an in-coupling diffractive optical element (DOE) disposed in an exit pupil expander;

expanding an exit pupil of the received imaging light along a first coordinate axis in an intermediate DOE disposed in the exit pupil expander;

expanding the exit pupil along a second coordinate axis in an out-coupling DOE disposed in the exit pupil expander; and

outputting imaging light in a display with an expanded exit pupil relative to the input pupil along the first and second coordinate axes using the out-coupling DOE,

wherein the in-coupling DOE is configured to cause chromatic dispersion in the received imaging light and the out-coupling DOE is configured to cause chromatic dispersion in the output imaging light in an opposite direction to that caused in the in-coupling DOE.

16. The method of claim 15 in which the predetermined range of wavelengths covers at least 40 nm.

17. The method of claim 15 in which the predetermined range of wavelengths has sufficient width so that at least a portion of spectrum is capable of propagation in the exit pupil expander in total internal reflection over the entirety of the FOV of the input pupil.

18. The method of claim 15 in which the imager is further configured so that the imaging light spectrum is varied over the FOV of the input pupil so that only a portion of the spectrum that is capable of propagation within the exit pupil expander in total internal reflection at each angle of the FOV is utilized for a region of the FOV that includes that angle.

19. The method of claim 15 as performed in a near-eye display system.

20. The method of claim 15 in which the output imaging light provides a virtual display to a user of the near-eye display system.