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WO2024135974A1 - Dispositif de réalité augmentée basé sur un guide d'ondes incurvé, procédé de fonctionnement dudit dispositif, lunettes de réalité augmentée basées sur ledit dispositif - Google Patents

Dispositif de réalité augmentée basé sur un guide d'ondes incurvé, procédé de fonctionnement dudit dispositif, lunettes de réalité augmentée basées sur ledit dispositif Download PDF

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Publication number
WO2024135974A1
WO2024135974A1 PCT/KR2023/010613 KR2023010613W WO2024135974A1 WO 2024135974 A1 WO2024135974 A1 WO 2024135974A1 KR 2023010613 W KR2023010613 W KR 2023010613W WO 2024135974 A1 WO2024135974 A1 WO 2024135974A1
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Prior art keywords
diffractive optical
optical element
waveguide
coupling diffractive
curved waveguide
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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PCT/KR2023/010613
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English (en)
Inventor
Gavril Nikolaevich VOSTRIKOV
Nikolay Viktorovich Muravyev
Aleksandr Evgenyevich Angervaks
Roman Aleksandrovich Okun
Anastasia Sergeevna Perevoznikova
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Samsung Electronics Co Ltd
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Samsung Electronics Co Ltd
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Priority claimed from RU2022133304A external-priority patent/RU2801055C1/ru
Application filed by Samsung Electronics Co Ltd filed Critical Samsung Electronics Co Ltd
Priority to US18/455,257 priority Critical patent/US20240201429A1/en
Publication of WO2024135974A1 publication Critical patent/WO2024135974A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/0101—Head-up displays characterised by optical features
    • G02B2027/013—Head-up displays characterised by optical features comprising a combiner of particular shape, e.g. curvature
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays
    • G02B27/017—Head mounted
    • G02B2027/0178—Eyeglass type

Definitions

  • the disclosure relates to augmented reality devices. More particularly, the disclosure relates to augmented reality glasses.
  • Wearable augmented reality glasses are a personal device that a user can use as a source of video information (image) projected directly into the user eye in the form of a virtual image that complements a user surrounding real world.
  • image projected directly into the user eye in the form of a virtual image that complements a user surrounding real world.
  • FOV field of view
  • Such wearable devices can replace any source of video information for the user, such as (televisions) TVs, smartphones, etc.
  • An optical device that combines a virtual image with the user surrounding real world is an optical combiner.
  • planar (flat) waveguides are currently most widely used, on the surface of which diffractive optical elements (DOEs) for inputting, conversing and outputting optical radiation are located.
  • DOEs diffractive optical elements
  • a planar waveguide is a transparent plate made of an optical material with two plane-parallel surfaces.
  • a beam of parallel rays can propagate without distortions to any distance within such a waveguide.
  • Augmented reality devices with such combiners have low weight, small size, low cost, can provide a wide field of view, and have high transmissivity, that is, high transmission of a real image.
  • Curved waveguides located on the user head such that they go around the oval of the user head can be used as an optical combiner, wherein the glasses with such a combiner will be more compact and convenient, they will have smaller dimensions, a device with such a combiner will be more ergonomic and aesthetic.
  • the use of a curved waveguide as a combiner is associated with significant difficulties in converting and transmitting optical radiation therethrough.
  • a document US10983346B2 (publication date is 20.04.2021) is known from prior art.
  • This document discloses a curved waveguide-based display device, wherein a portion of the waveguide for inputting radiation is flat and a portion of the waveguide for outputting radiation is curved.
  • an out-coupling diffractive optical element (DOE) with a variable period is disposed, wherein all the radiation entering the waveguide from a projector is output based on the out-coupling DOE at one angle, that is, all the rays that are output from the waveguide are parallel each other, so that an image has no distortions.
  • DOE diffractive optical element
  • the disadvantage of the known device is the low quality of the image formed by such a combiner due to that a parallel beam of rays propagating without distortions within the flat portion of the waveguide, having passed into the curved portion of the waveguide, will be inevitably distorted when propagating along the curved portion of the waveguide because the angle of incidence of various rays from the parallel beam on the curved surface of the waveguide will be different due to curvature of this surface.
  • a device disclosed in a document WO 2022058740 A1 (publication date is 24.03.2022) is a closest prior art to the disclosure.
  • a combiner as a curved waveguide is used in the device.
  • the curved waveguide is a cylindrical concentric meniscus.
  • the cylindrical concentric meniscus is an optical detail whose surfaces are formed by cylindrical surfaces, wherein the axes of the cylinder surfaces of the waveguide coincide.
  • a radiation source in the disclosure is located on the axis of the cylindrical surfaces of the waveguide.
  • An in-coupling DOE has a constant period.
  • An additional cylindrical focusing lens is installed between the radiation source that is projected into the user eye and the in-coupling DOE.
  • each ray incident from the radiation source, which is disposed on the axis of the waveguide cylinder, on the in-coupling DOE will coincide with the direction of the normal to the waveguide surface at the point of incidence. Therefore, each ray from the radiation source will be input into the waveguide by the in-coupling DOE at the same angle.
  • a beam of such rays will propagate within the waveguide in the form of a concentric cylindrical meniscus for any distance while maintaining the angles of incidence and reflection relative to the ormal at the points of incidence on the inner and outer sides of the waveguide, that is, without distortions. This will allow this beam to be output using the out-coupling DOE from the waveguide, thus having formed an image for the user.
  • the proposed arrangement allows an aberration-free image of points located on the axis of the cylindrical surfaces of the waveguide in the case of zero aberrations of the additional cylindrical focusing lens to be formed.
  • the disadvantage of this arrangement is its bulkiness due to the requirements for location of the radiation source relative to the waveguide.
  • the proposed solutions allow creating a compact augmented reality device with a curved combiner that forms a quality image for the user that cannot be observed by an outsider.
  • an aspect of the disclosure is to provide augmented reality devices and augmented reality glasses.
  • an augmented reality display device includes a projector forming an initial image, a curved waveguide having the shape of a concentric cylindrical meniscus and comprising an in-coupling diffractive optical element and an out-coupling diffractive optical element, wherein a grating period (groove period) of the in-coupling diffractive optical element at each point of the in-coupling diffractive optical element is such that rays emanating from one point of the initial image undergo diffraction at the in-coupling diffractive optical element at the same angle relative to the normal to a surface of the curved waveguide at a point of incidence, wherein the curved waveguide is configured to propagate the rays of the initial image from the in-coupling diffractive optical element to the out-coupling diffractive optical element based on total internal reflection from surfaces of the curved waveguide, wherein, when propagating the rays of the initial image, angles of incidence on and of reflection from a
  • a diffraction grating period of the in-coupling diffractive optical element may be equal to a diffraction grating period of the out-coupling diffractive optical element.
  • the diffraction grating period of the in-coupling diffractive optical element is equal to the diffraction grating period of the out-coupling diffractive optical element in the center of the in-coupling diffractive optical element and in the center of a diffraction grating of the out-coupling diffractive optical element,
  • center of the initial image lies on the normal to the waveguide surface in the center of the in-coupling diffractive optical element
  • the center of an image formed by the out-coupling diffractive optical element lies on the normal to the waveguide surface in the center of the out-coupling diffractive optical element
  • x in is a linear coordinate of the point on the waveguide surface on which the ray falls along the O in X in axis in a coordinate system O in X in Y in Z in , wherein the center O in of the coordinate system is disposed at the center of the in-coupling diffractive optical element, the Z in axis is directed along the normal to the surface of the curved waveguide, the Y in axis is directed tangentially to the surface of the curved waveguide in the point O in along the length of the curved waveguide and perpendicularly to the Z in axis, the X in axis is directed along the generatrix of the cylindrical surface of the curved waveguide in the point O in across the width of the curved waveguide and perpendicularly to the Z in axis,
  • L in is a linear coordinate along the concave surface of the curved waveguide with the origin in the center O in of the in-coupling diffractive optical element
  • R1 is a curvature radius of the concave surface of the curved waveguide
  • T o is a diffraction grating period of the in-coupling diffractive optical element in the point where ray with a wavelength falling on the in-coupling diffractive optical element along the normal to the surface of the curved waveguide undergoes diffraction into a -1 st diffraction order by the in-coupling diffractive optical element,
  • grooves (grating groove) of the in-coupling diffractive optical element are parallel to the common axis of the cylindrical surfaces of the curved waveguide.
  • a variation of the period of the out-coupling diffractive optical element can be equal to:
  • L out is a linear coordinate along the concave surface of the curved waveguide in a cross-section Y out O out Z out with the origin in the center O out of the out-coupling diffractive optical element, where the period of the out-coupling diffractive optical element is equal to T o , the Z out axis is directed along the normal to the surface of the curved waveguide, the Y out axis is directed tangentially to the surface of the curved waveguide in the point O out along the length of the curved waveguide and perpendicularly to the Z out axis, the X out axis is directed tangentially to the surface of the curved waveguide in the point O out across the width of the curved waveguide and perpendicularly to the Z out axis,
  • R1 is a curvature radius of the concave surface of the curved waveguide
  • grooves (grating grooves) of the out-coupling diffractive optical element are parallel to the common axis of the cylindrical surfaces of the curved waveguide.
  • the device may further comprise two flat waveguides disposed between the projector and the in-coupling diffractive optical element, wherein each of the flat waveguides has a constant-period diffraction grating of the flat waveguide, wherein grooves of the diffraction grating of each flat waveguide are perpendicular to the axis of the cylindrical surfaces of the curved waveguide.
  • a method for operating an augmented reality device includes forming, by a projector, an initial image, inputting, by an in-coupling diffractive optical element, rays of an initial image into a curved waveguide, wherein rays emanating from one point of the initial image undergo diffraction at the in-coupling diffractive optical element at the same angle relative to the normal to a surface of the curved waveguide at a point of incidence, the rays inputted into the curved waveguide propagate within the curved waveguide by means of total internal reflection from surfaces of the curved waveguide, transforming, by means of the out-coupling diffractive optical element, the rays passed through the curved waveguide into parallel beams of rays to form a virtual image on a user retina.
  • augmented reality glasses include an element for left eye and an element for right eye, wherein each of the elements for left and right eye is the proposed augmented reality display device. Meanwhile, a distance between the centers of the out-coupling diffractive optical elements may correspond to a user interpupillary distance. Meanwhile, the normal to the waveguide surface in the center of the out-coupling diffractive optical element for right eye may be parallel to the normal to the waveguide surface in the center of the out-coupling diffractive optical element for left eye.
  • FIG. 1A illustrates a curved waveguide in isometry according to an embodiment of the disclosure:
  • FIG. 1B illustrates ray propagation at total internal reflection (TIR) angles within a curved waveguide in a plane perpendicular to its axis according to an embodiment of the disclosure
  • FIG. 2 illustrates a diffraction scheme of ray from a point radiation source on an in-coupling DOE in a cross-section Y in O in Z in according to an embodiment of the disclosure
  • FIG. 3 illustrates a diffraction scheme of ray from a point radiation source on an in-coupling DOE in a cross-section X in O in Z in according to an embodiment of the disclosure
  • FIG. 4 illustrates a path of rays of a parallel beam falling on an in-coupling DOE 5, whose period varies in accordance with Expression 1, in a plane perpendicular to an axis of a cylindrical surfaces of a curved waveguide according to an embodiment of the disclosure;
  • FIG. 5 illustrates an isometric view of ray propagation through a concentric cylindrical waveguide, an in-coupling DOE with a period variation expression according to Expression 1, an out-coupling DOE with a period variation expression according to Expression 2 according to an embodiment of the disclosure;
  • FIG. 6 illustrates a diffraction scheme of ray from a projector with an exit pupil of finite dimensions, which forms an image at infinity, on an in-coupling DOE in a cross-section Y out O out Z out according to an embodiment of the disclosure
  • FIGS. 7A and 7B illustrate graphs of angular error distribution of an in-coupling DOE a) with a period variation expression according to Expression 1, b) with a specified period variation expression according to various embodiments of the disclosure;
  • FIG. 8 illustrates a diffraction scheme of ray on an out-coupling DOE in a cross-section Y out O out Z out according to an embodiment of the disclosure
  • FIGS. 9A and 9B illustrate graphs of angular error distribution of an out-coupling DOE a) with a period variation expression according to Expression 2, b) with a specified period variation expression according to various embodiments of the disclosure;
  • FIG. 10 illustrates a diagram of an installation for recording a DOE (HOE) with a variable period on a film-type holographic material according to an embodiment of the disclosure
  • FIGS. 11A and 11B illustrate an isometric view of ray propagation through exit pupil expansion waveguides of a projector and a concentric cylindrical waveguide according to various embodiments of the disclosure.
  • FIG. 12 schematically illustrates a proposed augmented reality device forming a virtual image for two eyes according to an embodiment of the disclosure.
  • An augmented reality device based on a curved optical combiner is proposed.
  • the disclosure allows a user to see a distortion-free image at any width of a radiation beam entering from a projection system.
  • the disclosure also provides a wide field of view for a user and is a compact device.
  • improved image quality is provided, which is maintained in a wide range of the user eye position relative to the optical combiner.
  • a virtual image is an imaginary image obtained by extensions of rays that do not converge in the object space.
  • the essence of the virtual image for use in augmented reality devices consists in that such an image is to be imaginary, otherwise the user will not see it.
  • a real image is a virtual image of physically existing objects.
  • An optical combiner is an optical device providing the formation of an image in front of the user that complements the user surrounding real world (virtual image), while not interfering with the user observation of the surrounding real world.
  • a curved waveguide as a concentric cylindrical meniscus is used as an optical combiner, the waveguide having an in-coupling diffractive optical element (DOE) and an out-coupling DOE, whose centers are located in the same plane perpendicular to the axis of the cylindrical surfaces of the waveguide.
  • DOE diffractive optical element
  • a field of view (FOV) of an optical system is an angular range within which a user can observe an image formed by the optical system.
  • the center of the field of view corresponds to the center of the image, and the edge of the field of view corresponds to the edge of the maximum possible size of the image.
  • Eye motion box is an area within which the eye, when moving, can see a total field of view formed by an augmented reality device without losses and with predetermined quality.
  • Eye motion box is a linear area in space within which the total field of view enters the eye pupil, i.e., rays from any point of an image. Outside this area, a part of the field of view is lost partially or completely, i.e., outside this area, the rays from the entire virtual image or some part thereof do not enter the entrance pupil of the eye.
  • the eye is constantly moving, rotating and at the same time the eye pupil is constantly displacing.
  • the eye motion box of an optical combiner of the augmented reality device should correspond to the range of possible motion of the user eye.
  • An exit pupil (or a pupil of an optical system) is a paraxial image of an aperture diaphragm in image space, formed by the following part of the optical system in a ray forward path. This term is well-established in optics.
  • the main property of the exit pupil is that at any point thereof there are rays forming the total field of view.
  • technical solutions are known for multiplying the exit pupil, that is, increasing its size, without increasing size of an optical system in the direction of an optical axis.
  • Classical optics allows size of the exit pupil to be increased, but at the same time, size of the optical system increases significantly, whereas waveguide optics, due to the multiple reflection of beams of rays inside the waveguide, allows doing this without increasing size in the direction of the optical axis of the optical system.
  • a concentric meniscus is an optical detail formed by two spherical waveguide surfaces, whose curvature centers are at one point.
  • FIG. 1A illustrates a curved waveguide in isometry according to an embodiment of the disclosure.
  • FIG. 1B illustrates ray propagation at total internal reflection (TIR) angles within a curved waveguide in a plane perpendicular to its axis according to an embodiment of the disclosure.
  • a concentric cylindrical meniscus (curved waveguide 1) is an optical detail formed by two cylindrical surfaces whose axes coincide, as shown in FIG. 1A.
  • the common axis of the concave and convex cylindrical surfaces of the curved waveguide is denoted by reference number 2.
  • the concentric cylindrical meniscus will be represented by two arcs of circles limiting the internal volume of the curved waveguide whose centers coincide at the point C, as shown in FIG. 1B.
  • the normals to the convex and concave surfaces at all points of such a cross-section of the waveguide will lie in the same cross-section plane.
  • Angles of ray incidence for concave (first surface) and convex (second surface) surfaces are related by the relationship: .
  • Such properties of ray propagation within a concentric cylindrical meniscus i.e., maintaining the angle of incidence and reflection relative to the normal at all points of incidence for the concave and convex surface, are used in the disclosure to form a virtual image using a curved combiner.
  • a beam of rays propagating within a concentric cylindrical meniscus in the range of TIR angles, as shown in FIG. 1B, which have equal angles of incidence and reflection relative to the normal at the point of incidence for the concave and convex surface, can transmit the brightness of one direction of the field of view from a region of the in-coupling DOE (diffractive optical element) to a region of the out-coupling DOE through the curved waveguide.
  • a beam of rays has the following particulars:
  • the in-coupling DOE should appropriately transform the beam falling thereon from a radiation source that constitutes the image that is presented to the user. To do this, each ray of said radiation beam should undergoes diffraction such that the angle of the beam diffracted inside the waveguide relative to the normal to the waveguide surface should be equal for each such ray for all points of incidence on the in-coupling DOE.
  • a projector is generally a radiation source with an optical system.
  • the optical system of the projector builds an image of the radiation source at some distance from the projector, usually at infinity.
  • the radiation source that builds the initial image can be divided into point radiation sources located at some distance from the curved waveguide. Further, the following options for the location of one point radiation source will be considered a) a point radiation source is at a finite distance from the concave surface of the curved waveguide 1, b) a point radiation source is on the axis of the cylindrical surfaces of the curved waveguide 1, c) a point radiation source is at infinity, it is a projector in practical implementation whose lens transfers the image of the radiation source to infinity, this option is interesting in view of practical application.
  • L in is a linear coordinate along the concave surface of the waveguide, the origin is in the center of the in-coupling DOE at the point O in .
  • FIG. 2 illustrates a diffraction scheme of ray from a point radiation source on an in-coupling DOE in a cross-section Y in O in Z in according to an embodiment of the disclosure.
  • 3 is presentation of a radiation source
  • 1a is a concave surface of a waveguide
  • C is a center of the waveguide curvature
  • ⁇ is an angle of a ray under consideration from the source relative to a O in Z in axis
  • ⁇ is an angle between a point of incidence of the ray on the waveguide and the direction of the axis O in Z in from the center of curvature of the waveguide C, uniquely related to a linear coordinate L in on the concave surface of the waveguide
  • ⁇ is an angle of incidence of the ray relative to the normal to the waveguide surface at the point of incidence
  • y in , z in are coordinates of the waveguide surface point on which the ray falls in a coordinate system O in X in Y in Z in
  • n w is refractive index of the waveguide are denoted.
  • the radiation source 3 will form a diverging homocentric beam that will fall on the region of the in-coupling DOE.
  • This case in a plane perpendicular to the axis of the cylindrical surfaces of the waveguide is illustrated by FIG. 2.
  • R1 is a curvature radius of the concave surface of the waveguide.
  • the rays will be input into the curved waveguide at different angles, and on the side of the out-coupling DOE, it will be impossible to understand which rays from which point of the image fall on one or another point of the out-coupling DOE, i.e., in this case a high-quality image will be impossible to be formed.
  • FIG. 3 illustrates a diffraction scheme of ray from a point radiation source on an in-coupling DOE in a cross-section X in O in Z in according to an embodiment of the disclosure.
  • x in is a linear coordinate of the point of the waveguide surface on which the ray falls along the O in X in axis in a coordinate system O in X in Y in Z in .
  • the period of the in-coupling DOE for each point of the in-coupling DOE with coordinates x in and L in is selected such that all rays emanating from one point of the initial image undergo diffraction on the in-coupling diffractive optical element at the same angle relative to the normal to the surface of the curved waveguide at the point of incidence.
  • the in-coupling DOE is a constant-period T 0 diffraction grating with grooves parallel to the O in X in axis, that is, and .
  • Another important particular case (c) is the location of the radiation source forming an initial image at infinity. In view of practical application, this is the most common case because small-sized projectors used in wearable augmented reality devices as a radiation source, as a rule, form an image at infinity.
  • Z LGT -
  • a beam falling on the in-coupling DOE from each direction of the field of view is a parallel beam.
  • the Expression 1 implements the period variation expression for the in-coupling DOE at each point of the in-coupling DOE, wherein such period variation provides the same diffraction angle at the in-coupling DOE relative to the normal to the surface of the curved waveguide at the point of incidence for the rays emanating from one point of an initial image in the case when the projector forms an image (presentation of a radiation source) at infinity.
  • the in-coupling DOE is a diffraction grating, whose grooves are parallel to the axis of the cylindrical surfaces of the waveguide because , and the grating period in the plane perpendicular to the axis of the cylindrical surfaces of the curved waveguide varies according to the above Expression 1.
  • Such a case of location of the in-coupling DOE is shown in isometry in FIG. 5.
  • FIG. 4 illustrates a path of rays of a parallel beam falling on an in-coupling DOE 5, whose period varies in accordance with Expression 1, in a plane perpendicular to an axis of a cylindrical surfaces of a curved waveguide of the proposed combiner according to an embodiment of the disclosure.
  • FIG. 4 it illustrates a combiner comprising the curved waveguide 1, the in-coupling DOE 5, and in addition an out-coupling DOE 6 for forming an image is placed further downstream along the ray path at the opposite end of the waveguide 1. Due to the partial output of the rays many times reflected in the waveguide 1, at several points on the surface of the out-coupling DOE 6, an eye motion box 7 extended in the direction of propagation of the rays is formed, which is conditionally shown by a dotted line in the form of a diaphragm 7, which limits the eye motion box, as shown in FIG. 4.
  • the image When the user eye is located within the motion box indicated by the arrow, the image will be formed on the user eye retina, wherein the center of the image field is located on an axis coinciding with the normal to the surface of the curved waveguide in the center of the out-coupling diffractive optical element.
  • the out-coupling DOE 6 can also have a variable period according to the relationship:
  • L out is a linear coordinate along the inner surface of the waveguide in a cross-section Y out O out Z out , wherein the origin is in the center O out of the out-coupling DOE 6.
  • the center O out of the coordinate system is disposed at the center of the out-coupling DOE, where the period of the out-coupling DOE is equal to T o
  • the Z out axis is directed along the normal to the surface of the curved waveguide
  • the Y out axis is directed tangentially to the surface of the curved waveguide in the point O out along the length of the curved waveguide and perpendicularly to the Z out axis
  • the X out axis is directed tangentially to the surface of the curved waveguide in the point O out across the width of the curved waveguide and perpendicularly to the Z out axis.
  • the period of the out-coupling DOE 6 in the cross-section X out O out Z out should be infinite to form an image (imaging) at infinity, that is, the grooves of the out-coupling DOE 6 are to be parallel to the common axis 2 of the cylindrical surfaces of the curved waveguide, as shown in FIG. 5, wherein this is a mandatory requirement for imaging at infinity.
  • FIG. 5 illustrates an isometric view of ray propagation through a concentric cylindrical waveguide, an in-coupling DOE with a period variation expression according to Expression 1, an out-coupling DOE with a period variation expression according to Expression 2 according to an embodiment of the disclosure.
  • the Expression 1 provides input of a parallel beam into the curved waveguide, and the Expression 2 provides output of an aberration-free parallel beam, and the equality of T 0 at the central points of the in-coupling DOE and the out-coupling DOE provides output of a parallel beam incident in the direction of the normal in the center of the in-coupling DOE, in the direction of the normal in the center of the out-coupling DOE.
  • the Expressions 1and 2 are derived from the diffraction grating formula and geometry.
  • the parallel beam of rays formed by the out-coupling DOE 6 will be directed along the normal 9 to the surface of the waveguide 4 in the center of the out-coupling DOE 6, and the user eye motion box will be also symmetrical with respect to the normal 9 to the surface of the waveguide 4 at the center of the out-coupling DOE 6, as shown in FIG. 4.
  • Such a connection between the in-coupling and out-coupling DOEs will provide the symmetry of the concave surface of the waveguide 1a for the rays falling on the in-coupling DOE 5 from the radiation source and for the rays emerging from the out-coupling DOE 6 and forming the eye motion box 7.
  • This will provide minimal off-axis aberrations (coma, astigmatism) and minimal chromatic aberrations (position and magnification chromatism) in the image formed by such a combiner because a symmetrical optical system is known to provide minimal aberrations.
  • the in-coupling DOE 5 and the out-coupling DOE 6 are located on the concave surface of the curved waveguide 1, the surface having the form of a concentric cylindrical meniscus.
  • the grooves of the diffraction gratings of these DOEs are parallel to the axis 2 of the cylindrical surfaces of the waveguide 1, which is a particular case of making the grooves of the diffraction gratings of the in-coupling and out-coupling DOEs.
  • the ray falling on the center of the in-coupling DOE 5, whose period variation expression corresponds to the Expression 1 undergoes diffraction on the in-coupling DOE 5 in the direction of the normal to the surface of the waveguide 8 and propagates at the TIR angles within the waveguide 1.
  • this ray undergoes diffraction at the out-coupling DOE 6 and is output from the waveguide, forming a set of parallel rays. If the period at the center of the out-coupling DOE will be equal to the period on the in-coupling DOE at the point of incidence of a corresponding ray, then the ray fell in the center of the out-coupling DOE 6 will be outputted from the waveguide 1 along direction of the normal 9 to the concave surface of the waveguide and will cross the axis 2 of the cylindrical surfaces of the waveguide 1.
  • the proposed combiner will provide the user with virtual images of points spatially extended along the vertical axis of an object (parallel to the O in X in axis), without aberrations. However, images of other points spatially extended along the horizontal axis of the object (parallel to the O in Y in axis), such a combiner will form with some aberration.
  • FIG. 6 illustrates a diffraction scheme of ray from a projector with an exit pupil of finite dimensions, which forms an image at infinity, on an in-coupling DOE in a cross-section Y out O out Z out according to an embodiment of the disclosure.
  • a concave surface of the waveguide 1 with the in-coupling DOE (not shown in FIG. 6), an exit pupil 10 of the projector, a center of curvature of the waveguide surfaces, i.e., the point C are denoted.
  • FIGS. 7A and 7B illustrate graphs of angular error distribution of an in-coupling DOE a) with a period variation expression according to Expression 1, b) with a specified period variation expression according to various embodiments of the disclosure.
  • the error of ray input is zero, that is, the rays from the center of the field of view will be entered without aberrations for any y pupil .
  • this error is not equal to zero, and the maximum error value being of about 4 arcmin corresponds to the ray from the upper region of the exit pupil of the projector for the field of view of 12 o.
  • the Expression 1 can be approximated, for example, by a 4 th order polynomial, to correct the period variation expression for the in-coupling DOE in order to reduce the input error.
  • the coefficients of this polynomial can be selected such that the maximum error of ray input will be several times smaller for all combinations of position angles and coordinates at the exit pupil of the projector.
  • the result of calculating the errors of ray input of such in-coupling DOE is shown in FIG. 7B.
  • the maximum error is 0.8 arcmin, which is more than 5 times less than the maximum error of the initial in-coupling DOE with the period variation according to the analytical Expression 1.
  • FIG. 8 illustrates a diffraction scheme of ray on an out-coupling DOE in a cross-section Y out O out Z out according to an embodiment of the disclosure.
  • a concave surface 1a of the waveguide 1 with the out-coupling DOE (not shown in FIG. 8), an eye motion box 7, whose plane is spaced apart at 15 mm from the center of the out-coupling DOE, a center of curvature of the waveguide surfaces, i.e., the point C are denoted.
  • FIGS. 9A and 9B illustrate graphs of angular error distribution of an out-coupling DOE a) with a period variation expression according to Expression 2, b) with a specified period variation expression according to various embodiments of the disclosure.
  • the center of the coordinate system X out O out Z out is located at the center of the out-coupling DOE, and L out is a linear coordinate along the curved surface of the waveguide with the origin also being in the center of the out-coupling DOE, i.e., in the point O out . Then the ray that has fallen from the waveguide to the out-coupling DOE will undergo diffraction and leave the waveguide at angle , fall on an eye motion plane at a point with a height y eye_box .
  • a result of operation of the out-coupling DOE can be analyzed by sorting through all possible combinations of the angles of ray incidence corresponding to the field of view and the linear coordinates L out on the out-coupling DOE and by obtaining a set of the corresponding ⁇ z and y eye_box .
  • an eye pupil size which is several times smaller than a size of an eye motion box. To do this, it is necessary to pick over all possible positions of the user eye pupil within the eye motion box and, for each such position, to calculate all the rays falling into such a pupil from one or another direction of the field of view .
  • the out-coupling DOE with the period variation expression according to Expression 2 and with an eye pupil size of 4 mm, the eye motion box of 12 mm, the dependence of the angular error of the formed virtual image with a width of 24° is shown in FIG. 9A.
  • the center of the field is displayed without aberrations for all pupil positions, and when the direction in the field deviates from the center, the error increases, wherein the maximum error for the selected system parameters is around 2 arcmin.
  • the Expression 2 for the out-coupling DOE can also be corrected in order to reduce the maximum error.
  • the period variation expression is also interpolated by a 4 th order polynomial, whose coefficients are selected such that for all combinations of the position of the pupil in the eye motion box for different directions of the field of view, the angular error of the rays falling on the user pupil is minimal.
  • the dependence of the angular error of such out-coupling DOE with the specified period variation expression is shown in FIG. 9B. In this case, the maximum angular error was succeeded for reducing to 1.5 arcmin.
  • holographic optical elements recorded on a thin film material can be used.
  • One of the known schemes of an installation for recording holographic optical elements with a variable period, which can be used as an in-coupling or out-coupling DOE for the proposed combiner is shown in FIG. 10.
  • FIG. 10 illustrates a diagram of an installation for recording a DOE (HOE) with a variable period on a film-type holographic material according to an embodiment of the disclosure.
  • DOE DOE
  • a laser radiation source 11 a cubic beam splitter 12, that splits the laser beam into two beams by energy, controlled shutters 13, telescopic systems 14 for increasing the transverse dimensions of the beam, motorized linear translators 15, on the tables of which rotating motorized platforms with flat mirrors 16 are installed, screens 17 limiting the beam to form an element of given dimensions and to exclude flare light within a working prism 18, a cylindrical lens 19 providing modulation of the period of a holographic diffraction grating to be recorded are denoted.
  • the axes of the cylindrical surfaces of the lens 19 are oriented perpendicularly to the drawing plane of FIG. 10, thereby the diffraction grating recorded on the photosensitive holographic material is a set of parallel grooves (zones with equal refractive index) also perpendicular to the drawing plane of FIG. 10.
  • the parameters of the cylindrical lens 19, its position relative to the working prism 18, as well as the position and orientation of the mirrors on the rotating motorized platforms 16 are selected such that the period variation expression for an interference pattern in the plane of location of the photosensitive holographic material 20 corresponds to the Expression 1 or 2 or other required expressions for dependence of a variation in the DOE period.
  • the variable L in for the in-coupling DOE and the variable L out for the out-coupling DOE correspond to a linear direct coordinate on the plane of the working prism 18.
  • the photosensitive holographic material 20 is a thin transparent film that can be transferred from the flat surface of the working prism 18 to the curved surface of the cylindrical concentric waveguide.
  • the curved combiner of the proposed configuration can be manufactured.
  • the out-coupling DOE 6 forms a horizontally extended eye motion zone 7 due to multiple output of the ray each time it falls on the out-coupling DOE 6 along the ray propagation path within the waveguide 1.
  • the exit pupil of the projector 21 of FIG. 11A is necessary to be expanded.
  • two additional flat waveguides 22 and 23 can be used, as shown in FIG. 11B, with DOEs having a constant period of diffraction gratings, and grooves of the diffraction gratings of which are oriented horizontally (perpendicularly to the axis 2 of the cylindrical surfaces of the waveguide 1).
  • FIG. 11A illustrates a ray path through a curved combiner in isometry according to an embodiment of the disclosure
  • FIG. 11B illustrates a vertical cross-section in a region of a projector and an in-coupling DOE according to an embodiment of the disclosure.
  • FIGS. 11A and 11B they explain the principle of operation of such additional flat waveguides that expand the exit pupil of the projector.
  • Two additional flat waveguides 22 and 23, which expand the exit pupil of the projector 21 vertically, are installed between the projector 21 and the in-coupling DOE 5 located on the concave surface of the curved waveguide 1.
  • the flat waveguide 22 with a multiplying DOE expands the exit pupil of the projector down
  • the flat waveguide 23 with a multiplying DOE expands the exit pupil of the projector upwards, as shown in FIG. 11B.
  • the beam of rays thus transformed falls from the projector on the in-coupling DOE 5, is introduced into the waveguide 1, propagates within it, and is outputted by the out-coupling DOE 6.
  • each ray leaving the projector 21 will be multiplied in a two-dimensional region of the eye motion box, similar to that shown in FIG. 11A for one ray of the projector.
  • FIG. 12 illustrates a scheme of augmented reality glasses comprising an element for left a) eye and an element for right b) eye of a user according to an embodiment of the disclosure.
  • Each of the elements for left and right eye is the augmented reality display device described above.
  • a curved waveguide 1 on the surface of which the in-coupling DOE 5 and out-coupling DOE 6 are located, a user eye motion box 7, a projector 21 forming a virtual image at infinity, flat waveguides 22 and 23 for expanding the exit pupil of the microprojector 21 vertically, user eye 24 are denoted.
  • the center of the eye motion box 7, where the user eye 24 is supposedly located, is disposed on the axis 9 coinciding with the normal to the surface of the waveguide 1 at the center of the out-coupling DOE 6, as shown in FIG. 12.
  • the rays constituting the image output by the projector 21 are directed at angle of 20°-40° with respect to the projector body 21, as shown in FIG. 12, which can be achieved by introducing prisms or mirrors into the optical scheme of the microprojector.
  • the most comfortable option for the user will be such arrangement of the elements for left and right eye, in which the distance between the center of the out-coupling DOE 6 of the element for right eye and the center of the out-coupling DOE 6 element for left eye corresponds to the interpupillary distance of the user, and also when the normal to the waveguide surface in the center of the out-coupling diffractive optical element for right eye is parallel to the normal to the waveguide surface in the center of the out-coupling diffractive optical element for left eye.
  • a distortion-free sharp image of augmented reality can be formed due to the disclosure.
  • the proposed arrangement of the augmented reality device with the curved combiner will permit making it compact and similar in appearance to user traditional sunglasses or glasses for vision correction.
  • Such device due to its compactness and wearing comfort, can be used continuously all day long, which will allow the user to be in information environment formed personally for him(her) using means, such as social networks, media, messaging programs, information search tools processing user queries, including on elements from the user surrounding real world.
  • the augmented reality display device may include a projector forming an initial image.
  • the augmented reality display device may include a curved waveguide having a shape of a concentric cylindrical meniscus and comprising an in-coupling diffractive optical element and an out-coupling diffractive optical element.
  • a grating period of the in-coupling diffractive optical element at each point of the in-coupling diffractive optical element may be such that rays emanating from one point of the initial image undergo diffraction at the in-coupling diffractive optical element at a same angle relative to a normal to a surface of the curved waveguide at a point of incidence.
  • the curved waveguide may be configured to propagate rays of the initial image from the in-coupling diffractive optical element to the out-coupling diffractive optical element based on total internal reflection from surfaces of the curved waveguide, wherein, when propagating the rays of the initial image, angles of incidence on and of reflection from a concave surface of the curved waveguide inside the curved waveguide are equal to each other and constant, and angles of incidence on and of reflection from a convex surface of the curved waveguide inside the curved waveguide are equal to each other and constant.
  • the out-coupling diffractive optical element may be configured to form a virtual image on a user retina by converting the rays passed through the curved waveguide and falling on the out-coupling diffractive optical element into parallel beams of rays.
  • a diffraction grating period of the in-coupling diffractive optical element may be equal to a diffraction grating period of the out-coupling diffractive optical element.
  • the diffraction grating period of the in-coupling diffractive optical element may be equal to the diffraction grating period of the out-coupling diffractive optical element in a center of the in-coupling diffractive optical element and in the center of the diffraction grating of the out-coupling diffractive optical element.
  • the center of the initial image may lie on the normal to a waveguide surface in the center of the in-coupling diffractive optical element, and the center of an image formed by the out-coupling diffractive optical element lies on the normal to the waveguide surface in the center of the out-coupling diffractive optical element.
  • xin is a linear coordinate of the point on the waveguide surface on which the ray falls along an OinXin axis in a coordinate system OinXinYinZin, wherein a center Oin of a coordinate system is disposed at the center of the in-coupling diffractive optical element, a Zin axis is directed along the normal to the surface of the curved waveguide, a Yin axis is directed tangentially to the surface of the curved waveguide in a point O in along a length of the curved waveguide and perpendicularly to the Zin axis, an Xin axis is directed along a generatrix of a cylindrical surface of the curved waveguide in the point O in across a width of the curved waveguide and perpendicularly to the Zin axis;
  • Lin is a linear coordinate along the concave surface of the curved waveguide with an origin in the center Oin of the in-coupling diffractive optical element
  • R1 is a curvature radius of the concave surface of the curved waveguide
  • T o is a diffraction grating period of the in-coupling diffractive optical element in the point where ray with a wavelength falling on the in-coupling diffractive optical element along the normal to the surface of the curved waveguide undergoes diffraction into a -1 st diffraction order by the in-coupling diffractive optical element.
  • grating grooves of the in-coupling diffractive optical element may be parallel to a common axis of the cylindrical surface of the curved waveguide.
  • a variation of a period of the out-coupling diffractive optical element is equal to:
  • Lout is a linear coordinate along the concave surface of the curved waveguide in a cross-section YoutOoutZout with an origin in a center Oout of the out-coupling diffractive optical element, where the period of the out-coupling diffractive optical element is equal to T o , a Zout axis is directed along the normal to the surface of the curved waveguide, a Yout axis is directed tangentially to the surface of the curved waveguide in a point ⁇ out along a length of the curved waveguide and perpendicularly to the Zout axis, an Xout axis is directed tangentially to the surface of the curved waveguide in the point ⁇ out across a width of the curved waveguide and perpendicularly to the Zout axis,
  • R1 is a curvature radius of the concave surface of the curved waveguide
  • grating grooves of the out-coupling diffractive optical element may be parallel to a common axis of the cylindrical surface of the curved waveguide.
  • the augmented reality display device may include two flat waveguides disposed between the projector and the in-coupling diffractive optical element.
  • each of the flat waveguides may have a constant-period diffraction grating of the flat waveguide.
  • grooves of the diffraction grating of each flat waveguide may be perpendicular to an axis of the cylindrical surface of the curved waveguide.
  • the method may include forming, by a projector, an initial image.
  • the method may include inputting, by an in-coupling diffractive optical element, rays of the initial image into a curved waveguide.
  • rays emanating from one point of the initial image may undergo diffraction at the in-coupling diffractive optical element at a same angle relative to a normal to a surface of the curved waveguide at a point of incidence.
  • the rays inputted into the curved waveguide may propagate within the curved waveguide based on total internal reflection from surfaces of the curved waveguide.
  • the augmented reality device may include augmented reality glasses comprising an element for left eye and an element for right eye.
  • each of the elements for left and right eye may be an augmented reality display device.
  • a distance between centers of an out-coupling diffractive optical elements may correspond to a user interpupillary distance.
  • the normal to a waveguide surface in a center of the out-coupling diffractive optical element for right eye may be parallel to the normal to the waveguide surface in the center of the out-coupling diffractive optical element for left eye.
  • the diffraction grating period of the in-coupling diffractive optical element may be equal to the diffraction grating period of the out-coupling diffractive optical element in the center of the in-coupling diffractive optical element and in the center of the diffraction grating of the out-coupling diffractive optical element.
  • the center of the initial image may lie on the normal to the waveguide surface in the center of the in-coupling diffractive optical element, and the center of an image formed by the out-coupling diffractive optical element lies on the normal to the waveguide surface in the center of the out-coupling diffractive optical element.

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Abstract

L'invention concerne un dispositif de réalité augmentée basé sur un guide d'ondes incurvé. Le dispositif comprend un projecteur et un guide d'ondes incurvé. Le guide d'ondes a la forme d'un ménisque cylindrique concentrique et comprend un élément optique diffractif de couplage et un élément optique diffractif de découplage, une période de réseau d'un réseau de diffraction de l'élément optique diffractif de couplage à chaque point de l'élément optique diffractif de couplage est telle que des rayons provenant d'un point d'une image initiale sont entrés dans le guide d'ondes incurvé dans chaque point de l'élément optique diffractif de couplage au même angle par rapport à une normale à une surface du guide d'ondes incurvé au niveau d'un point d'incidence de rayons, et au moins au niveau d'un point sur chacun des éléments optiques diffractifs, une période de réseau de diffraction de l'élément optique diffractif de couplage est égale à une période de réseau de diffraction de l'élément optique diffractif de découplage.
PCT/KR2023/010613 2022-12-19 2023-07-21 Dispositif de réalité augmentée basé sur un guide d'ondes incurvé, procédé de fonctionnement dudit dispositif, lunettes de réalité augmentée basées sur ledit dispositif Ceased WO2024135974A1 (fr)

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US18/455,257 US20240201429A1 (en) 2022-12-19 2023-08-24 Curved waveguide-based augmented reality device, method for operation of said device, augmented reality glasses based on said device

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RU2022133304A RU2801055C1 (ru) 2022-12-19 Устройство дополненной реальности на основе изогнутного волновода, способ работы упомянутого устройства, очки дополненной реальности на основе упомянутого устройства
RU2022133304 2022-12-19

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120300311A1 (en) * 2010-01-25 2012-11-29 Bae Systems Plc Projection display
US20180292676A1 (en) * 2017-04-05 2018-10-11 Thalmic Labs Inc. Systems, devices, and methods for curved waveguides integrated with curved eyeglass lenses
US10228565B1 (en) * 2016-05-27 2019-03-12 Facebook Technologies, Llc Variable focus waveguide display
WO2021098744A1 (fr) * 2019-11-18 2021-05-27 苏州苏大维格科技集团股份有限公司 Lentille de guide d'ondes et lunettes à réalité augmentée
WO2022058740A1 (fr) * 2020-09-21 2022-03-24 TruLife Optics Limited Système optique avec guide d'ondes cylindrique

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120300311A1 (en) * 2010-01-25 2012-11-29 Bae Systems Plc Projection display
US10228565B1 (en) * 2016-05-27 2019-03-12 Facebook Technologies, Llc Variable focus waveguide display
US20180292676A1 (en) * 2017-04-05 2018-10-11 Thalmic Labs Inc. Systems, devices, and methods for curved waveguides integrated with curved eyeglass lenses
WO2021098744A1 (fr) * 2019-11-18 2021-05-27 苏州苏大维格科技集团股份有限公司 Lentille de guide d'ondes et lunettes à réalité augmentée
WO2022058740A1 (fr) * 2020-09-21 2022-03-24 TruLife Optics Limited Système optique avec guide d'ondes cylindrique

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