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KR-20260066193-A - MIXED REALITY COMBINER

KR20260066193AKR 20260066193 AKR20260066193 AKR 20260066193AKR-20260066193-A

Abstract

The optical waveguide combiner has an output coupler comprising an array of embedded partial-reflection dielectric mirrors for extending and coupling a virtual, optionally colored image generated by a laser display engine into a user EMB. The dielectric mirrors are configured to have a wavelength band for each lasing band of the laser display engine—the wavelength band includes wavelengths of light within the lasing band and within the wavelength range where the lasing band is expected to drift—a reflection angle range exhibiting a first reflectance, a transmission angle range exhibiting a second reflectance less than the first reflectance, and a transmission angle range having high transmittance for natural light incident on the facets.

Inventors

  • 크리키 로넨
  • 샬린 엘라드
  • 단지거 요차이

Assignees

  • 루머스 리미티드

Dates

Publication Date
20260512
Application Date
20210222
Priority Date
20200224

Claims (9)

  1. As an optical system for a head-mounted display, A laser display engine comprising at least one laser diode (LD) configured to emit light within a lasing bandwidth to generate a virtual image; and A waveguide comprising: (i) first and second substantially parallel total internal reflecting surfaces configured to guide the light from the virtual image by a series of total internal reflecting (TIR); and (ii) an output coupler comprising an array of partial reflection facets embedded within the waveguide and inclined at a tilt angle with respect to the TIR surfaces—the facets being configured to couple the light emanating from the waveguide toward an eye-motion box. The above facets include coatings designed to provide a facet wavelength band corresponding to the light emitted by the at least one LD, wherein the facet wavelength band is wider than the lasing bandwidth to accommodate wavelength variations of the at least one LD; For light within the facet wavelength band, the coatings are configured such that the facets have a first reflectance for light incident thereon within a first angle of incidence range, wherein the first angle of incidence range is a function of the inclination angle of the facets and the angle range of light guided by a series of internal total reflections, and are configured to have a lower second reflectance for light incident thereon within a second angle of incidence range, wherein the first reflectance is substantially constant over the facet wavelength band; An optical system in which the above coatings are further configured to provide a see-through angle range for transmitting visible light from an external environment through substantially achromatic transmission.
  2. An optical system according to claim 1, wherein the lasing bandwidth of the at least one LD is 1 nm to 2 nm and the facet wavelength band is at least 20 nm.
  3. An optical system according to claim 1, wherein the first reflectance varies by less than 5% over the facet wavelength band.
  4. An optical system according to claim 1, wherein the first angle of incidence range corresponds to an image waveguide field of view (wFOV) containing light to be coupled out of the waveguide, and the second angle of incidence range corresponds to a conjugate wFOV.
  5. An optical system according to paragraph 4, wherein the first reflectance is greater than 9% and the second reflectance is less than 2%.
  6. An optical system according to claim 1, wherein the laser display engine comprises red, green, and blue (RGB) laser diodes, and the facets are configured to have individual facet wavelength bands for each of the red, green, and blue laser diodes.
  7. An optical system according to claim 1, wherein the coatings are dielectric coatings comprising at least one material selected from the group consisting of hafnium dioxide ( HfO₂ ), magnesium fluoride ( MgF₂ ) , and tantalum pentoxide ( Ta₂O₅ ).
  8. An optical system according to claim 1, further comprising a second waveguide optically coupled to the output coupler of the waveguide, wherein the second waveguide is configured to expand the aperture of the virtual image in a second direction orthogonal to the first expansion direction provided by the waveguide.
  9. An optical system according to claim 1, wherein the transmittance of the visible light within the projection angle range is 85% or more.

Description

Mixed Reality Combiner Related applications This application claims the benefit of U.S. provisional application No. 62/980,469 filed on February 24, 2020 and U.S. provisional application No. 63/001,567 filed on March 30, 2020, under 35 U.S.C. 119(e). Technology field Embodiments of the present disclosure relate to an optical waveguide system configured to receive an image from a laser display engine in a relatively small input aperture and to transmit the image to exit the waveguide in an expanded output coupling region to fill an enlarged eye motion box for the user to view. The surging head-mounted displays (HMDs) and smart eyewear used to provide users with various new realities—augmented reality (AR), mixed reality (MR), and parallel reality—overlay computer-generated "virtual images" onto "real images" that the user sees of the real environment within the user's field of view (FOV). Virtual images may, for example, provide the user with entertainment and/or informational materials related to real images, actions performed by the user, and/or explicit or implicit user requests. Images presented to the user that include both real and virtual images may be referred to as extended reality (XR) images, and any various hardware configured to provide XR images to the user may be broadly referred to as XR displays. In the optical system of an XR display, a computer-controlled display engine, such as an LCoS (liquid crystal on silicon), OLED (organic light emitting diode), or LBS (laser beam scanning) microdisplay, provides virtual images. An optical element referred to as a combiner passes ambient light, allowing the user to view the real environment; to provide XR images to the user, it receives virtual images provided by the display engine and superimposes them onto real images. Typically, virtual images provided by a display engine are relatively small, having characteristic dimensions of about 5 mm or less. The combiner receives small virtual images at a relatively small input aperture and propagates them to an output coupler—which outputs the virtual images into the eye motion box (EMB) through the combiner's exit aperture. When the user's eye is positioned within the EMB, the virtual images pass through the user's spherical cavity and onto the user's retina, appearing in XR images as features of the actual images the user sees through the combiner. To fill the EMB so that the user can comfortably view the virtual images without straining excessively to align their eyes with the combiner, the combiner is generally configured to have a relatively large and extended aperture—through which the combiner transmits many copies of the virtual images into the EMB. The optical system of an actual XR display is generally required to satisfy a complex interplay of ergonomic, technical, and financial constraints. The optical system is preferably configured to have a comfortably large EMB, be preferably small, lightweight, and energy-efficient, and provide clear virtual images without overly noticeable artifacts such as image ghosts. An embodiment of the present disclosure relates to providing an optical waveguide combiner having an output coupler comprising an array of embedded dielectric partial reflection mirrors (hereinafter also referred to as facets) for extending and coupling a virtual, optionally colored image generated by a laser display engine into a user EMB. For light in a wavelength band provided by a laser used by the engine to generate the virtual image, the facets are configured to reflect incident light of a first range of angles of incidence into the user EMB with a relatively large reflectance. At a second range of angles of incidence different from the first range, the facets are configured to have a relatively low reflectance and to transmit light within substantially the same laser wavelength band with a relatively large transmittance. Transmittance and reflectance exhibit relatively small variability across the first and second angle ranges and across the wavelength range spanning the laser wavelength band. The facets are formed to have a substantially achromatic transmittance for visible light from the environment (also referred to as natural light). Optionally, the display engine includes at least one laser that provides light of red, green, and blue (RGB) bands to the display engine and processes the light to generate virtual RGB color images. In an embodiment, the combiner introduces color virtual images into the EMB having relatively high RGB image resolution and relatively low contamination by image artifacts. In an embodiment, the waveguide combiner comprises a waveguide having first and second parallel total internal reflecting (TIR) surfaces. Light from a display engine enters the waveguide, is repeatedly reflected from the TIR surfaces and bounces back and forth between the TIR surfaces, propagates along the waveguide in a reduced waveguide FOV (wFOV), reaches and is incident on facets