Spherical Birdbath Mirror Having A Decoupled Aspheric

• US 20160041390A1
• Filed: 08/07/2014
• Published: 02/11/2016
• Est. Priority Date: 08/07/2014
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: McEldowney, Scott, Poon, Yarn Chee, Hudman, Joshua A, Wall, R Andrew, Robbins, Steven John
• Granted Patent: US 10,746,994 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 17/08 Catadioptric systems used in non-imaging applications G02B19/00
• CPC Class Codes: G02B 2027/011 comprising device for correcting geometrical aberrations, distortion
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• 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 3/04 with continuous faces that are rotationally symmetrical but deviate from a true sphere , e.g. so called "aspheric" lenses
• CPC Class Codes: G02B 5/10 with curved faces
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001

Abstract

The technology provides decoupling an aspheric optical element from a birdbath optical element in a near-eye display (NED) device. One or more aspheric lens are used with a spherical birdbath reflective mirror in a projection light engine of a NED device. A projection light engine provides image light (or other information), by way of the spherical birdbath reflective mirror and at least one aspheric lens, to a near-eye display of the NED device. The spherical birdbath reflective mirror collimates and reflects the image light to an exit pupil external to the projection light engine. Decoupling the aspheric optical element from the spherical birdbath reflective mirror may enable high modulation transfer function (MTF) and improved manufacturability of the projection light engine. The NED device having aspheric optical elements decoupled from a birdbath optical element may be positioned by a support structure in a head-mounted display (HMD) or head-up display (HUD).

Claims

1. An apparatus comprising:

a display to provide an image light;

a beam splitter to beam split the image light;

an optical element to receive the image light from the beam splitter, the optical element reflects and collimates the image light; and

an aspheric optical element to correct an aberration in the image light.

2. The apparatus of claim 1, wherein the aspheric optical element includes a first and second aspheric meniscus lens,

wherein the optical element is a spherical mirror,

wherein the display is a microdisplay,

wherein the spherical mirror reflects and collimates the image light to an external exit pupil, and

wherein the first and second aspheric meniscus lens are disposed between the spherical mirror and the external exit pupil.

3. The apparatus of claim 1, wherein the aspheric optical element includes an aspheric meniscus lens,

wherein the optical element is a spherical mirror,

wherein the display includes a microdisplay, and

wherein the aspheric meniscus lens is disposed between the spherical mirror and the beam splitter.

4. The apparatus of claim 1, further comprising:

a quarter wave retarder disposed between the optical element and the beam splitter;

a doublet disposed between the optical element and the beam splitter; and

a color select filter disposed between the beam splitter and an external exit pupil,

wherein the aspheric optical element includes an aspheric meniscus doublet disposed between the beam splitter and the external exit pupil,

wherein the optical element is a spherical mirror,

wherein the display includes a microdisplay,

wherein the beam splitter is a type of beam splitter selected from a group consisting of cube, plate, wire-grid polarizer and internally refractive.

5. The apparatus of claim 3, comprising:

an illumination unit including at least one light source,

wherein the microdisplay outputs the image light by reflecting light from the at least on light source.

6. The apparatus of claim 4, further comprising at least one polarizer to polarize the image light,

wherein the microdisplay is a self-emissive microdisplay.

7. The apparatus of claim 3, comprising:

a reflective surface to reflect the image light from the microdisplay to the beam splitter;

a spherical doublet disposed between the reflective surface and the beam splitter;

a prepolarizer disposed between the spherical doublet and the reflective surface; and

a field corrector disposed between the microdisplay and the reflective surface.

8. The apparatus of claim 7, wherein the apparatus is included in projection light engine of a near-eye display device, the near-eye display device includes the projection light engine and a near-eye display that includes a waveguide.

9. The apparatus of claim 8, wherein the projection light engine is included in a housing, wherein the projection light engine outputs the image light at an exit pupil that is external to the housing.

10. A method comprising:

directing image light along a first optical path to a reflective mirror;

collimating and reflecting the image light, by the reflective mirror, along a second optical path to an exit pupil outside a housing of the reflective mirror;

polarizing the image light in at least one of the first optical path and the second optical path; and

correcting an optical aberration of the image light by an aspheric optical element disposed along the second optical path.

11. The method of claim 10, comprising:

receiving, at an input of a diffractive waveguide, the image light from the first optical path.

12. The method of claim 10, wherein polarizing the image light is performed at least in part by a polarizing beam splitter,

wherein the aspheric optical element includes a first aspheric lens and a second aspheric lens, and

wherein the first aspheric lens and second aspheric lens are disposed along the second optical path between the polarizing beam splitter and the exit pupil.

13. The method of claim 10, wherein polarizing the image light is performed at least in part by a polarizing beam splitter,

wherein the aspheric optical element is an aspheric lens, and

wherein the aspheric lens is disposed along the second optical path between the reflective mirror and the polarizing beam splitter.

14. The method claim 13, wherein directing image light along the first optical path to the reflective mirror comprises:

correcting a field of the image light from a microdisplay;

reflecting the image light to a prepolarizer; and

prepolarizing the image light by the prepolarizer.

15. The method of claim 14 wherein directing image light along the first optical path to the reflective mirror comprises:

receiving the image light, by a spherical doublet, from the prepolarizer; and

outputting the image light, by the spherical doublet, to the polarizing beam splitter.

16. An apparatus comprising:

a computer system that provides an electronic signal representing image data; and

a head-mounted display that provides image data in response to the electronic signal, wherein the head-mounted display includes;

a near-eye display device including;

a projection light engine including;

a microdisplay to provide the image data in response to the electronic signal;

a reflective surface to reflective the image data from the microdisplay;

a polarizing beam splitter to polarized and split beam the image data from the reflective surface;

a spherical mirror to reflect and collimate the image data, from the polarizing beam splitter, to an exit pupil external to the projection light engine; and

an aspheric meniscus lens to correct the image data, and

near-eye display having a waveguide to receive the image data.

17. The apparatus of claim 16, wherein the aspheric meniscus lens is disposed on an optical path between the spherical mirror and the polarizing beam splitter.

18. The apparatus of claim 16, wherein the aspheric meniscus lens is one of two aspheric lens disposed on an optical path between the polarizing beam splitter and the near-eye display.

19. The apparatus of claim 18, wherein the waveguide of the near-eye display is a diffractive waveguide.

20. The apparatus of claim 19, wherein the waveguide of the near-eye display is a surface relief grating waveguide.