CN113534478A

CN113534478A - Optical assembly, display system and manufacturing method

Info

Publication number: CN113534478A
Application number: CN202010288635.1A
Authority: CN
Inventors: 杨鑫; 黄正宇
Original assignee: Individual
Current assignee: Beijing Yilian Technology Co ltd
Priority date: 2020-04-14
Filing date: 2020-04-14
Publication date: 2021-10-22

Abstract

The present disclosure relates to an optical assembly comprising: a beam generator configured to emit a beam group of a cone of light distribution; a light-transmissive medium having parallel first and second surfaces; a first beam combiner located on the first surface; and a second beam combiner located on the second surface, wherein the first beam combiner is configured to receive the set of beams of the cone of light distribution and to change its direction of propagation such that at least a portion thereof propagates through the optically transmissive medium onto the second beam combiner; the second beam combiner is configured to change the direction of propagation of the beam incident thereon from the first beam combiner to continue propagating away from the second beam combiner at a different angle, wherein beams from a group of beams of the same cone of light distribution exit the second beam combiner to converge at a point. The optical assembly is provided with two coaxially arranged beam combiners, so that an image is amplified in equal proportion after being modulated and is coupled out and imaged on a retina, and therefore, the retina imaging without distortion and a large visual field is realized.

Description

Optical assembly, display system and manufacturing method

Technical Field

The present disclosure relates generally to the field of optical displays, and more particularly, to an optical assembly, a display system, and a method of manufacturing.

Background

With the development of computer technology and display technology, Virtual Reality (VR) technology for experiencing a Virtual world through a computer simulation system, and Augmented Reality (AR) technology and Mixed Reality (MR) technology for fusing display contents into a real environment background have been rapidly developed.

The near-eye VR, AR and MR display technology combining the VR, AR and MR technologies with near-eye display is an important novel display technology, and can bring unprecedented visual experience and man-machine interaction. Near-eye VR display mainly pursues the virtual display of the large visual field of submergence formula, and it is the virtual reality display helmet that corresponds. The near-eye AR and MR technologies aim to realize perspective virtual-real fusion, and correspondingly, augmented reality intelligent glasses or helmets are used. In principle, near-eye display devices for AR as well as MR are also called virtual reality techniques in case of blocking ambient light from entering the user's eyes.

The near-eye display device is generally constructed as a helmet display device or a display device in a glasses shape, and is used for imaging an image displayed by a micro display chip at a far distance through an optical system, enabling human eyes to directly see the displayed amplified image at the far distance through the near-eye display device, realizing spatial perception positioning by combining an SLAM technology, realizing interaction through technologies such as gesture recognition, voice recognition and eyeball tracking, and the like, is a novel display technology with important potential commercial application value, and is considered as a novel display technology expected to replace a smart phone.

In recent years, the virtual reality display device has been developed explosively, and many kinds of devices have been provided. International major companies such as Oculus, HTC, Sony, Samsung, etc. have introduced virtual reality helmet display devices, respectively, and research and development of virtual reality display products are actively being carried out in domestic parallel reality, Roc photoelectricity, etc. The near-to-eye display devices used in these virtual reality head-mounted displays are mostly based on the single positive lens imaging principle, i.e. by placing the display near the object focal plane of the single positive lens, the display will get an erect, magnified virtual image at infinity at the object side of the lens after passing through the single positive lens.

Near-eye display devices for AR and MR have also been greatly developed in recent years. Such as Microsoft corporation and Magic Leap corporation, have introduced augmented reality products based on augmented reality optical engines that utilize diffractive light waveguides to perform the functions of image in-coupling, out-coupling, and pupil expansion. The technology realizes binocular parallax-based three-dimensional display or double-layer depth volumetric display or common two-dimensional display. And the domestic clear JING optical-electrical, Daojia-resistant and Gordon-valley technologies and the like adopt an array waveguide or a free-form surface AR eyepiece to realize augmented reality. By adopting the technology, two-dimensional display or three-dimensional display can be realized, but the three-dimensional display has the problem of convergence adjustment conflict, namely the convergence of the eye focus and the binocular vision axis of a viewer is inconsistent, so that the problems of visual fatigue, vertigo and the like are caused, and particularly, the discomfort is stronger when the viewer watches a virtual scene with a short distance. Wearing this type of near-to-eye display device for a long period of time is potentially harmful to the vision of young people with immature vision.

One of the biggest challenges for augmented reality helmets or glasses at present is to develop a smaller and more compact optical display core assembly, implement a three-dimensional display technology or a comfortable two-dimensional display without conflict of convergence adjustment, make users more comfortable to wear for a long time, and meet some specific requirements for use in specific occasions.

In addition, the retinal imaging technology is a display technology in which an image is directly projected to the retina by optical means. In the traditional retina imaging technology, a display chip such as LCoS (liquid crystal on silicon) is used as an image carrier, imaging is carried out through a lens system, a semi-transparent semi-reflecting mirror is used for guiding an image into human eyes, and ambient light penetrates through the human eyes to realize penetration type display. The lens group of the scheme has a large volume, the semi-transparent semi-reflecting mirror can attenuate the ambient light brightness by half, and the realization of the compact large-view-field display module which does not attenuate the ambient light is an important problem to be solved urgently in the retina imaging technology. In addition, the above problems are solved, and improvements in the existing optical device and the manufacturing method thereof are also required.

The statements in this background section merely represent techniques known to the public and are not, of course, representative of the prior art.

Disclosure of Invention

In view of at least one of the deficiencies of the prior art, the present disclosure provides an optical assembly comprising:

a beam generator configured to emit a beam group of a cone of light distribution;

a light-transmissive medium having a first surface and a second surface, the first surface being parallel to the second surface;

a first beam combiner located on a first surface of the light-transmissive medium; and

a second beam combiner located on a second surface of the light-transmissive medium,

wherein the first beam combiner is configured to receive the set of beams of the light cone distribution and change its propagation direction such that at least a portion thereof propagates through the optically transparent medium onto the second beam combiner; and the second beam combiner is configured to change the propagation direction of the beams incident thereon from the first beam combiner to enable the beams to continuously propagate away from the second beam combiner at different angles, wherein the beams from the beam group with the same light cone distribution are converged at one point after leaving the second beam combiner after being changed in direction by the first beam combiner and the second beam combiner.

According to an aspect of the invention, the beam group of the light cone distribution forms an irradiation area on the first beam combiner in equal proportion to an irradiation area on the second beam combiner.

According to an aspect of the invention, the first beam combiner and the second beam combiner do not overlap in a direction perpendicular to an optical axis direction, and a main direction of the beam group of the light cone distribution is perpendicular to the first beam combiner and the second beam combiner.

According to one aspect of the invention, the marginal rays of the set of rays of the cone of rays pass through the extension of the first beam combiner without passing through the second beam combiner.

According to one aspect of the invention, the first beam combiner is configured such that all beams exiting therefrom propagate through the light-transmissive medium onto the second beam combiner.

According to an aspect of the invention, the optical assembly has an entrance pupil and an exit pupil, the vertex of the cone of light is the entrance pupil, and the point at which the beams of light from the group of beams of the same cone of light distribution converge after leaving the second beam combiner is the exit pupil.

According to one aspect of the invention, the optical beam generator comprises an image source and a micro-electromechanical system,

wherein the image source is configured to generate a laser beam carrying color information and/or brightness information of an image pixel; the micro-electro-mechanical system is configured to scan the laser beam to form a beam group of the light cone distribution,

wherein the laser beam is a monochromatic or three-color laser beam.

According to an aspect of the invention, the beam generator comprises:

a light source, wherein the light source is a monochromatic or tricolor laser light source, an LED light source or an OLED light source, and emits divergent illumination light;

one or more of a DMD, LCoS, LCD configured to be loadable with an image and to modulate light impinging thereon from the light source in accordance with the image;

a diaphragm or lens configured to receive the modulated light to form a set of beams of the cone of light distribution.

According to an aspect of the invention, the beam generator comprises:

a lens configured to receive the divergent illumination light emitted by the light source and converge to the apex of the cone of light;

one or more of a DMD, LCoS, LCD, or other device, positioned between the lens and the vertex, and configured to load an image and modulate light impinging thereon after passing through the lens according to the image.

According to one aspect of the invention, the MEMS comprises a MEMS galvanometer, and an image generated by the image source is formed by scanning beamlets carrying color information and/or brightness information of image pixels from lasers with different wavelengths through the MEMS galvanometer, and the image source comprises a plurality of lasers with different wavelengths, a controller and a beam combiner, wherein the controller is coupled to the lasers with different wavelengths and controls the lasers with different wavelengths to emit laser beams, and the laser beams of the lasers with different wavelengths are incident to the beam combiner and combined into near-parallel beamlets whose propagation paths are spatially overlapped.

According to one aspect of the invention, the beam combiner comprises a lens group and optical thin film light splitting sheets respectively corresponding to the wavelengths of the lasers with different wavelengths, wherein the lens group is configured to adjust the divergence angle and/or the diameter of the laser beam emitted by the lasers, and the laser beam is projected onto the corresponding optical thin film light splitting sheets to form the near-parallel thin light beams with the spatially coincident propagation paths through reflection or transmission, wherein the lens group can comprise a liquid lens or a liquid crystal lens, and the equivalent focal length of the lens group can be adjusted through external voltage control so as to control the divergence angle and/or the diameter of the laser beam emitted by the lasers.

According to an aspect of the present invention, the beam combiner further includes a stop, a wave plate, a polarizing plate, an attenuation plate disposed between the lens group and the optical film splitter, and a micro-motor coupled to the lens group, the micro-motor being capable of adjusting a relative position between lenses in the lens group to adjust a divergence angle and/or a diameter of a light beam emitted from the lens group.

According to an aspect of the invention, the light beams of different directions in the set of light beams carry color information and/or brightness information of different image pixels.

According to one aspect of the invention, the first beam combiner comprises a first diffractive optical element, the light beam groups of the light cone distribution are diffracted when being incident to different positions of the first diffractive optical element, the propagation direction of the diffracted light is changed and continues to propagate in the light-transmitting medium, and the diffracted light is incident to different positions of the second beam combiner;

the second beam combiner comprises a second diffractive optical element, the beams from the first diffractive optical element are diffracted when being transmitted to different positions of the second diffractive optical element in different directions, the transmission directions are changed and enter the free space, and the beams which are transmitted to the free space and are diffracted in different directions from different positions of the second diffractive optical element are converged to the point in the free space.

According to an aspect of the invention, the first and second diffractive optical elements are independently volume holographic optical elements, the first and second diffractive optical elements being one of the following combinations:

the first diffractive optical element is a transmissive volume holographic optical element and the second diffractive optical element is a reflective volume holographic optical element;

the first diffractive optical element is a transmissive volume holographic optical element and the second diffractive optical element is a transmissive volume holographic optical element;

the first diffractive optical element is a reflective volume holographic optical element and the second diffractive optical element is a transmissive volume holographic optical element; and

the first diffractive optical element is a reflective volume hologram optical element and the second diffractive optical element is a reflective volume hologram optical element.

According to one aspect of the invention, the volume holographic optical element comprises a single color volume holographic optical element that diffracts laser light of different wavelengths of the plurality of lasers.

According to one aspect of the present invention, the volume hologram optical element includes a plurality of monochromatic volume hologram optical elements aligned exactly and stacked together, corresponding to the number of the plurality of lasers, each piece of the monochromatic volume hologram optical element diffracting only laser light of a corresponding wavelength and not diffracting laser light of other wavelengths.

According to one aspect of the invention, the volume holographic optical element comprises a plurality of volume holographic optical elements that are precisely aligned and stacked together, the number of the plurality of volume holographic optical elements being less than the number of the plurality of lasers, at least one of the plurality of volume holographic optical elements diffracting at least two wavelengths of laser light of the plurality of lasers and not diffracting other wavelengths of laser light; the remaining volume hologram optical elements diffract the remaining laser light of one of the other wavelengths, but do not diffract the remaining laser light of the other wavelengths.

According to one aspect of the invention, the volume holographic optical element comprises a single monochromatic volume holographic optical element that diffracts laser light of only one wavelength.

According to one aspect of the present invention, the first diffractive optical element and the second diffractive optical element are independently one selected from the group consisting of the single color volume holographic optical element, the plurality of single color volume holographic optical elements aligned and stacked together accurately and corresponding to the number of lasers, the plurality of single color volume holographic optical elements aligned and stacked together accurately and less than the number of lasers, and the single color volume holographic optical element.

The invention also relates to a display system comprising an optical assembly as described above.

According to one aspect of the invention, the display system is a virtual reality display system or an augmented reality display system.

According to an aspect of the invention, the display system further comprises an image generation unit configured to generate an image to be displayed, the image generation unit being coupled to the light beam generator, the light beams of different directions in the group of light beams emitted by the light beam generator carrying color information and/or brightness information of different pixels in the image.

According to one aspect of the invention, the display system comprises a left-eye display unit and a right-eye display unit, wherein the left-eye display unit and the right-eye display unit each comprise an optical assembly as described above.

The invention also relates to the use of an optical assembly as described above or a display system as described above for near-eye display.

The present invention also relates to an image projection method of an optical system, comprising:

step S81: generating a light beam group with light cone distribution;

step S82: the light beam group distributed by the light cone is incident to a first light beam synthesizer on the first surface of a light-transmitting medium, and the propagation direction of the light beam incident on the first light beam synthesizer is changed by the first light beam synthesizer so that the light beam enters the light-transmitting medium at different angles to be propagated continuously;

step S83: changing the propagation direction of the light beams propagating in the light-transmitting medium and incident on the second beam combiner by a second beam combiner on a second surface of the light-transmitting medium so that the light beams leave the second beam combiner at different angles to continue propagating, wherein the light beams from the light beam group with the same light cone distribution converge at one point after leaving the second beam combiner,

wherein the first surface is parallel to the second surface.

According to an aspect of the present invention, the optical system has an entrance pupil and an exit pupil, the vertex of the cone of light is the entrance pupil, and the point at which the light beams from the group of light beams of the same cone of light distribution converge after leaving the second beam combiner is the exit pupil.

According to one aspect of the invention, the beam generator comprises a laser light source and a micro-electro-mechanical system,

wherein the step S81 includes:

step S811: emitting a light beam carrying color information and/or brightness information of an image pixel by using a laser light source;

step S812: and scanning the light beams emitted from the laser light source by using a micro-electro-mechanical system to form a light beam group with the light cone distribution.

According to an aspect of the present invention, the step S81 includes:

utilizing a light source to emit divergent illumination light to irradiate a display screen, wherein the light source is a monochromatic or three-color laser light source, an LED light source or an OLED light source, and the display screen is a DMD, an LCoS or an LCD;

loading an image in the display screen, and modulating light irradiated on the display screen by the light source according to the image;

the modulated light is shaped into a beam group of the light cone distribution by means of a diaphragm or a lens.

According to an aspect of the present invention, the step S81 includes:

a light source is used for emitting divergent illumination light to irradiate a lens, and the divergent illumination light is converged to the vertex of the light cone after passing through the lens, wherein the light source is a monochromatic or three-color laser light source, an LED light source or an OLED light source;

the light beam passing through the lens irradiates on a display screen between the lens and the vertex, the display screen is a DMD, an LCoS or an LCD, an image is loaded in the display screen, and the light irradiating on the display screen from the lens is modulated according to the image.

According to an aspect of the invention, the image projection method is implemented with an optical assembly as described above or a display system as described above.

The present invention also relates to a method of manufacturing an optical element, comprising:

step S91: providing a light-transmitting medium, wherein the light-transmitting medium is provided with a first surface and a second surface which are parallel to each other, a first photosensitive film/first photosensitive plate is positioned on the first surface, and a second photosensitive film/second photosensitive plate is positioned on the second surface;

step S92: emitting laser by using a laser;

step S93: splitting the laser light into a first laser beam and a second laser beam;

step S94: splitting the first laser beam into a third laser beam and a fourth laser beam;

step S95: converging the third laser beam to a first point outside the light-transmitting medium, and emitting the third laser beam to the first photosensitive film/first photosensitive plate after the third laser beam is emitted from the first point;

step S96: converging the fourth laser beam to a second point outside the light-transmitting medium, and emitting the fourth laser beam from the second point to the first photosensitive film/first photosensitive plate;

step S97: and the third laser beam converged to the first point and the fourth laser beam converged to the second point generate interference exposure inside the photosensitive material of the first photosensitive film/first photosensitive plate to obtain the first integral holographic optical element.

According to one aspect of the invention, the method further comprises:

step S98: enabling the fourth laser beam to penetrate through the first photosensitive film/first photosensitive plate, enter the light-transmitting medium and be incident on the second photosensitive film/second photosensitive plate;

step S99: converging the second laser beam to a third point outside the light-transmitting medium after passing through the second photosensitive film/second photosensitive plate;

step S100: and the fourth laser beam passing through the first photosensitive film/first photosensitive plate and entering the light-transmitting medium and the second laser beam converged to the third point generate interference exposure in the photosensitive material of the second photosensitive film/second photosensitive plate to obtain a second volume holographic optical element.

According to an aspect of the present invention, a wedge prism is disposed on the first photosensitive film/first photosensitive web, wherein the step S96 includes: the fourth laser beam passes through one surface of the wedge prism and is incident on the first photosensitive film/first photosensitive plate at an angle that is increased relative to a vertical axis of the first photosensitive film/first photosensitive plate.

According to an aspect of the present invention, the step S95 includes: and the third laser beam passes through the surface of the wedge-shaped prism, which is parallel to the first photosensitive film/first photosensitive plate, and enters the first photosensitive film/first photosensitive plate.

According to an aspect of the present invention, the photosensitive materials of the first photosensitive film/first photosensitive plate and the second photosensitive film/second photosensitive plate are full-color photosensitive materials, and the step S92 includes: a plurality of lasers are utilized to emit laser beams with different wavelengths, and the laser beams are emitted after being combined;

the step S97 includes: simultaneously performing interference exposure inside the photosensitive material of the first photosensitive film/first photosensitive plate corresponding to different wavelengths of the plurality of lasers;

the step S100 includes: and simultaneously performing interference exposure inside the photosensitive material of the second photosensitive film/second photosensitive plate corresponding to different wavelengths of the plurality of lasers.

According to an aspect of the present invention, the photosensitive materials of the first photosensitive film/first photosensitive plate and the second photosensitive film/second photosensitive plate are full-color photosensitive materials, and the step S92 includes: sequentially emitting laser beams with different wavelengths by using a plurality of lasers and emitting the laser beams;

the step S97 includes: sequentially performing a plurality of interference exposures inside the photosensitive material of the first photosensitive film/first photosensitive plate corresponding to different wavelengths of the plurality of lasers;

the step S100 includes: a plurality of interference exposures are successively performed inside the photosensitive material of the second photosensitive film/second photosensitive web corresponding to different wavelengths of the plurality of lasers.

According to an aspect of the present invention, the photosensitive materials of the first photosensitive film/first photosensitive web and the second photosensitive film/second photosensitive web are monochrome photosensitive materials, and the step S92 includes: emitting laser beams with the wavelength corresponding to the monochromatic photosensitive material by using a laser and emitting the laser beams;

the step S97 includes: performing interference exposure inside the photosensitive material of the first photosensitive film/first photosensitive plate corresponding to the wavelength of the laser to obtain a first integral holographic optical element corresponding to the wavelength;

the step S100 includes: and performing interference exposure inside the photosensitive material of the second photosensitive film/second photosensitive plate corresponding to the wavelength of the laser to obtain a second volume holographic optical element corresponding to the wavelength.

According to one aspect of the invention, the method further comprises: the first photosensitive film/first photosensitive plate and the second photosensitive film/second photosensitive plate that can expose light of different wavelengths are replaced, and the first volume hologram optical element and the second volume hologram optical element corresponding to the different wavelengths are obtained through the steps S92, S93, S94, S95, S96, S97, S98, S99, and S100.

According to an aspect of the present invention, the step S92 includes:

emitting laser beams with different wavelengths by a plurality of lasers;

combining the laser beams with different wavelengths through an optical film beam splitter; and

and filtering, collimating and expanding the beam of the laser beam after beam combination.

According to one aspect of the invention, the method further comprises:

the obtained first volume hologram optical element and the second volume hologram optical element were copied as masters, respectively.

The invention also relates to a volume holographic optical element, made by the method as described above.

According to one aspect of the invention, the volume holographic optical element is a transmissive volume holographic optical element or a reflective volume holographic optical element.

The invention also relates to an optical assembly comprising:

a first beam combiner comprising a first integral holographic optical element fabricated according to the method described above, located on a first surface of the light-transmissive medium; and

a second beam combiner comprising a second volume holographic optical element, fabricated according to the method described above, located on a second surface of the light-transmissive medium,

wherein the laser beam is a monochromatic or three-color laser beam.

According to an aspect of the invention, the beam generator comprises:

According to one aspect of the invention, the first volume holographic optical element and the second volume holographic optical element are one of the following combinations:

the first volume holographic optical element is a transmission volume holographic optical element, and the second volume holographic optical element is a reflection volume holographic optical element;

the first volume holographic optical element is a transmission volume holographic optical element, and the second volume holographic optical element is a transmission volume holographic optical element;

the first volume holographic optical element is a reflective volume holographic optical element, and the second volume holographic optical element is a transmissive volume holographic optical element; and

the first volume holographic optical element is a reflective volume holographic optical element and the second volume holographic optical element is a reflective volume holographic optical element.

According to one aspect of the invention, the first and second volume holographic optical elements are independently any of:

a single color volume holographic optical element that diffracts laser light of different wavelengths of the plurality of lasers;

the multiple monochromatic volume holographic optical elements corresponding to the number of the lasers are accurately aligned and stacked together, and each monochromatic volume holographic optical element only diffracts the laser with the corresponding wavelength and does not diffract the laser with other wavelengths;

a plurality of volume holographic optical elements, less than the plurality of lasers, precisely aligned and stacked together, at least one of the plurality of volume holographic optical elements diffracting at least two wavelengths of laser light from the plurality of lasers and not diffracting other wavelengths of laser light; the rest of the volume hologram optical elements diffract the laser light of one of the rest of the other wavelengths, but do not diffract the laser light of the other wavelengths;

a single monochromator holographic optical element which diffracts laser light of only one wavelength.

The invention also relates to an image projection method implemented with an optical assembly as described above or a display system as described above.

The problem of complicated bulky optical assembly among the traditional retina imaging technology is aimed at to this disclosure, through the combination of printing opacity medium and beam combiner, has realized compact display module assembly and display system, has important commercial using value in near-to-eye AR and VR display field.

In addition, the two coaxially arranged beam combiners are combined, so that the projected image is modulated to form an image amplified in equal proportion and is coupled out to be directly imaged on the retina of human eyes, the coaxial distortion-free augmented reality display is realized, and the problem of trapezoidal distortion of the image caused by the off-axis arrangement of the propagation direction of the image light and the beam combiners is solved.

The features and advantages described in the specification are not all inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings and specification. Moreover, it should be noted that the terminology used in the description has been chosen primarily for readability and instructional purposes, and may not have been chosen to delineate or circumscribe the inventive subject matter.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure. In the drawings:

fig. 1 shows an optical assembly according to a first aspect of the present disclosure;

FIG. 2 shows a schematic diagram of an optical assembly according to a first aspect of the present disclosure without image distortion;

FIG. 3 illustrates a transmissive/reflective optical assembly in accordance with a preferred embodiment of the present disclosure, wherein FIGS. 3A-3C employ different beam generator configurations;

FIG. 4 illustrates a transmissive/transmissive optical assembly according to a preferred embodiment of the present disclosure;

FIG. 5 illustrates a reflective/transmissive optical assembly according to a preferred embodiment of the present disclosure;

FIG. 6 illustrates a reflective/reflective optical assembly according to a preferred embodiment of the present disclosure;

FIG. 7 illustrates the structure of a volume holographic optical element according to a preferred embodiment of the present disclosure;

FIG. 8 illustrates an image projection method of an optical system according to a first aspect of the present disclosure;

FIG. 9 illustrates a method of manufacturing an optical element according to a second aspect of the present disclosure;

FIG. 10 is a schematic optical path diagram illustrating the fabrication of beam combiners by the fabrication method of FIG. 9, wherein the first beam combiner is transmissive and the second beam combiner is reflective;

fig. 11 is a schematic diagram showing an optical path of a beam combiner manufactured by the manufacturing method of fig. 9, in which a wedge prism having a trapezoidal section is added in fig. 11A, and a wedge prism having a triangular section is added in fig. 11B.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art can appreciate, the described embodiments can be modified in various different ways, without departing from the spirit or scope of the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

In the description of the present disclosure, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be considered as limiting the present disclosure. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present disclosure, "a plurality" means two or more unless specifically limited otherwise.

In the description of the present disclosure, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and the like are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present disclosure can be understood by those of ordinary skill in the art as appropriate. For example, the present disclosure uses the term "coupled" to indicate that the connection between two terminals can be direct connection, indirect connection through an intermediate medium, electrically wired connection, or wireless connection.

In the present disclosure, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise the first and second features being in direct contact, or may comprise the first and second features being in contact, not directly, but via another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the disclosure. To simplify the disclosure of the present disclosure, specific example components and arrangements are described below. Of course, they are merely examples and are not intended to limit the present disclosure. Moreover, the present disclosure may repeat reference numerals and/or reference letters in the various examples, which have been repeated for purposes of simplicity and clarity and do not in themselves dictate a relationship between the various embodiments and/or arrangements discussed. In addition, the present disclosure provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.

It is to be noted that, unless otherwise specified, technical or scientific terms used in the present disclosure shall have the ordinary meaning as understood by those skilled in the art to which the present invention pertains.

Specific embodiments of the present disclosure are described below in conjunction with the appended drawings, it being understood that the preferred embodiments described herein are merely for purposes of illustrating and explaining the present disclosure and are not intended to limit the present disclosure.

First aspect

A first aspect of the present disclosure is directed to an optical assembly (or "optical module") 10, as shown in fig. 1. This is described in detail below with reference to fig. 1.

As shown in fig. 1, the optical assembly 10 includes a beam generator 11, a first beam combiner 12, a light-transmissive medium 13, and a second beam combiner 14. Wherein the light beam generator 11 is configured to form a light beam group of a light cone distribution, wherein light beams of different directions in the light beam group may carry, for example, color information and/or brightness information of different image pixels. Referring to fig. 1, the light beam generator 11 generates a light cone with a divergence angle θ, wherein each light beam may individually carry color and/or brightness information of an image pixel. According to an embodiment of the present disclosure, the light beam generator 11 may scan to form the light beam group of the light cone distribution, for example, at a first time, the light beam generator 11 emits the light beam L1, at a second time, the light beam generator 11 emits the light beam L2, and between the first time and the second time, the light beam generator 11 emits the light beam between L1 and L2. Alternatively, the light beam generator 11 may emit all or part of the light beam group in the light cone at the same time, which is within the scope of the present disclosure.

Those skilled in the art will readily appreciate that the light beam generator 11 may form a continuous distribution of light beams in the light cone, or may form discrete light beams to form groups of light beams, e.g. individual light beams are not spread over any angle of the light cone, but are discrete. According to a preferred embodiment of the present disclosure, the optical assembly 10 has an entrance pupil 10-In and an exit pupil 10-Out, the apex of the light cone may be located at the location of the entrance pupil 10-In. In fig. 1, the divergence angle of the light cone is θ. The beam generator 11 may itself have a divergence angle theta such that the divergence angle of the beam emitted therefrom itself corresponds to the divergence angle theta of the cone of light. Or alternatively the beam generator 11 comprises a laser emitting a high-directivity beamlet, in which case the beam generator 11 may for example comprise scanning means for scanning the high-directivity beamlet emitted by the laser to form a cone of light with a divergence angle θ, as will be described in more detail below. Or alternatively the light beam generator 11 emits a converging light beam, the point of convergence being the position of the entrance pupil 10-In, i.e. the apex of the cone of light, the light passing through the point of convergence then being considered as a diverging light beam from the point of convergence. All of which are within the scope of the present disclosure. In addition, the light beam emitted by the light beam generator 11 may be a monochromatic light beam, or a polychromatic light beam formed by mixing a plurality of monochromatic lights. In addition to carrying color information, the light beam emitted by the light beam generator 11 may also carry brightness information. The thin beam in the present disclosure, or the thin beam with high directivity, for example, refers to the beam with a diameter less than 2 mm or less than 1mm (preferably less than 0.01mm), and a divergence angle of 0.02-0.03 degree or less.

In addition, those skilled in the art will readily understand that the light beams of the light cone distribution formed by the light beam generator 11 may be emitted simultaneously or at different times (e.g., formed by scanning), and all such light beams are within the scope of the present disclosure.

The person skilled in the art will readily understand that the light-transmitting medium may be a solid medium such as transparent glass, or may be air. When the light-transmitting medium is air, the fixing of the first beam combiner 12 and the second beam combiner 14 is fixed by an external fixing framework, so that the accuracy of the relative positions of the first beam combiner and the second beam combiner is ensured. In the following description, the light-transmitting medium 13 is made of a light-transmitting material in a solid form, and details about the case of using air as the light-transmitting medium will not be repeated. All of which are within the scope of the present disclosure.

The light-transmitting medium 13 is a solid light-transmitting material connected to the first beam combiner 12 and the second beam combiner 14, respectively, and has a free space (e.g., air) outside a part of the surface thereof. In the transparent medium 13, the light beam propagates from the first beam combiner 12 to the second beam combiner 14, and is modulated to leave the transparent medium and enter a free space (e.g., air). The refractive index of the light-transmitting medium 13 is larger than that of air.

The first beam combiner 12 is attached to one surface of the transparent medium 13, receives the light beam group of the light cone distribution formed by the light beam generator 11, and changes the propagation direction of the light beam so that the light beam propagates in the transparent medium 13 at different angles. The second beam combiner 14 is attached to the other surface of the transparent medium 13, receives the light beams that have been changed in direction by the first beam combiner 12 and propagated in the transparent medium 13, and changes the propagation direction of the light beams again so that the light beams enter a free space (for example, air) to continue to propagate at different angles, wherein the light beams from the light beam group with the same light cone distribution finally converge at a point in the free space (for example, air), which may be, for example, the exit pupil 10-Out of the optical assembly 10. As shown in fig. 1, any one of the light beams in the light cone distribution defined by the light beams L1 and L2 first enters the first beam combiner 12, is modulated by the first beam combiner 12, then propagates in the transparent medium 13 at different angles, enters the second beam combiner 14, is modulated by the second beam combiner 14, then changes the angle again, enters a free space (for example, air) through the transparent medium 13, continues to propagate, and finally converges at a point, i.e., the exit pupil 10-Out.

In fig. 1, the light beam emitted from the first beam combiner 12 is directly incident on the second beam combiner 14. It will be readily understood by those skilled in the art that it is also possible for the light beam exiting the first beam combiner 12 to enter the second beam combiner 14 after undergoing one or more total reflections on the surface of the optically transparent medium, and still fall within the scope of the present invention.

In accordance with the present disclosure, the first beam combiner 12 and the second beam combiner 14 are coaxially arranged. The term "coaxial" in this application essentially means that the main propagation direction of the image light is substantially parallel to the vertical axis of the beam combiner. The image light is, for example, a cone-shaped light beam group emitted from the light beam generator 11, and the main propagation direction is, for example, the direction of the center line of the cone-shaped light beam group.

According to a preferred embodiment of the present disclosure, the surface of the light-transmitting medium 13 to which the first beam combiner 12 is attached and the surface to which the second beam combiner 14 is attached are parallel to each other. Further, according to a preferred embodiment of the present disclosure, the first beam combiner 12 and the second beam combiner 14 do not overlap each other in a direction perpendicular to the optical axis (horizontal direction in fig. 1). The term "optical axis (direction)" in the present application refers to the direction of the central axis of the light cone formed by the light beam generator, and is actually represented as a vertically upward direction in the provided drawings. The direction of the "optical axis" is the same as the chief ray direction. The principal ray direction is the direction of the central ray of the divergent light. Since the approximately divergent spherical wave is coupled in and the approximately convergent spherical wave is coupled out in the embodiment of the present application, the light rays are not vertical except that the direction of the central principal ray is vertical to the beam combiner. In summary, in the present application, the image light has a plurality of propagation directions, wherein the "direction of the optical axis" is synonymous with the "principal ray direction" and the "main propagation direction of the image light".

Further in accordance with a preferred embodiment of the present disclosure, the minimum separation of the first beam combiner and the second beam combiner in a direction perpendicular to the optical axis should satisfy the condition that: the extension line of the marginal ray incident on the first beam combiner does not fall into the second beam combiner. Otherwise, crosstalk may occur during recording. That is, the divergent illumination light and the convergent illumination light recorded by the first beam combiner and the second beam combiner should not have an overlapping region, if any, where interference fringes are recorded, resulting in crosstalk to the results of the display. In addition, the first beam combiner 12 is not located in the optical path of the beams leaving the second beam combiner 14.

According to the present disclosure, the refractive index of each of the first beam combiner 12 and the second beam combiner 14 is greater than the refractive index of air. In the present disclosure, there is no particular limitation on the refractive indexes of the first beam combiner 12, the light-transmitting medium 13, and the second beam combiner 14 as long as they are all greater than the refractive index of air, and the above-described beam propagation route can be achieved. According to a preferred embodiment of the present disclosure, the refractive index of the first beam combiner 12 and the second beam combiner 14 are each the same as or close to the refractive index of the light-transmissive medium 13. According to a preferred embodiment of the present disclosure, the first beam combiner 12 and the second beam combiner 14 are made of the same material, and their refractive indices may be the same; or made of different materials, the refractive indices of which may be different. The beam combiner can be made of a photosensitive film or a transparent light-transmitting medium such as glass coated with a photosensitive material.

According to a preferred embodiment of the present disclosure, the first beam combiner 12 comprises, for example, a diffractive optical element. The diffractive optical element is attached to one surface of a light-transmitting medium 13, light beams in a light beam group with light cone distribution formed by the light beam generator 11 are diffracted when being transmitted to different positions of the diffractive optical element in different directions, the transmission direction is changed and enters the light-transmitting medium, and beamlets (corresponding to the same light cone) which enter the light-transmitting medium and are diffracted in different directions from different positions of the diffractive optical element are incident to different positions of a second light beam combiner 14.

According to a preferred embodiment of the present disclosure, the second beam combiner 14 comprises, for example, a diffractive optical element. The diffractive optical element is attached to the other surface of the light-transmitting medium 13, light beams which are modulated by the first beam combiner 12 and then propagate in the light-transmitting medium at different angles are diffracted when propagating to different positions of the diffractive optical element in different directions, the propagation direction is changed and enters a free space, and beamlets (corresponding to the same light cone) which enter the free space and are diffracted in different directions from different positions of the diffractive optical element are converged to the point in the free space.

The diffraction optical element can be a volume holographic optical element, can enable light with specific wavelength and specific direction to be diffracted, and the diffraction efficiency of light with other wavelengths and directions can be rapidly reduced, and has certain angle selectivity and wavelength selectivity. The first beam combiner and the second beam combiner may comprise any combination of transmissive volume holographic optical elements and reflective volume holographic optical elements, depending on the configuration of the actual components. In the following description, unless otherwise specified, the diffractive optical element refers to a transmissive volume holographic optical element or a reflective volume holographic optical element. The diffractive optical element may be, for example, a volume hologram optical element, which may be a transmissive volume hologram optical element or a reflective volume hologram optical element. As will be described in detail below.

The working principle of the optical assembly 10 shown in fig. 1 is described in detail below. In fig. 1, the light beam generator 11 forms a light beam group of a light cone distribution, for example, two light beams L1 and L2 at a boundary in the light beam group are taken as an example, and are incident on the first beam combiner 12 respectively (the incident points are, for example, at a point a and a point B in fig. 1). The first beam combiner 12 is, for example, a transmissive volume holographic optical element, which can diffract the light beam incident thereon regardless of the incident direction or angle, and the diffracted light beam enters the inside of the light-transmitting medium 13 to propagate and is incident on the second beam combiner 14 (the incident points are, for example, points C and D in fig. 1). The second beam combiner 14 is, for example, a reflective volume holographic optical element, which can diffract the light beam incident thereon regardless of the incident direction or angle, and the diffracted light beam passes through the light-transmitting medium 13 and converges at a point in free space, such as the exit pupil 10-Out of the optical assembly 10 shown in fig. 1.

Fig. 1 shows a combination of a first beam combiner 12 of the transmissive type and a second beam combiner 14 of the reflective type, in which the incident beams from the group of beams of the light cone distribution and the beams emitted after passing through the first beam combiner 12 are respectively located on both sides of the first beam combiner 12, and the first beam combiner 12 implements beam modulation of the transmissive type; the incident light beam from the light-transmitting medium and the light beam emitted after passing through the second beam combiner 14 are located on the same side of the second beam combiner 14, and the second beam combiner 14 implements the similar reflection type beam modulation. Similarly, the optical assembly 10 according to the present disclosure may also be implemented, for example, with a combination of a transmissive first beam combiner 12 and a transmissive second beam combiner 14, a combination of a reflective first beam combiner 12 and a transmissive second beam combiner 14, and a combination of a reflective first beam combiner 12 and a reflective second beam combiner 14, all of which have similar optical principles.

Note that "converging to a point", the "entrance pupil" and the "exit pupil" of the optical component in this disclosure may be either a point in space or a region in space. The essential reason that this region can be formed is that the volume hologram optical element has certain angle selectivity and wavelength selectivity, that is, the wavelength and propagation angle in the vicinity of the designed wavelength and propagation angle can be diffracted in a diffraction relationship, when the wavelength and propagation angle are far from the designed wavelength and propagation angle, the diffraction efficiency is rapidly decreased, and when the diffraction efficiency is decreased to a certain degree, it can be considered that no diffraction occurs. In the case where a certain diffraction efficiency is satisfied, the corresponding entrance pupil is no longer a point but a certain region, and thus the corresponding exit pupil is no longer a point but a region.

The optical assembly according to the present disclosure includes a beam generator, a first beam combiner, a light-transmitting medium, and a second beam combiner, which can effectively reduce the thickness of an associated optical module. Especially in the case of VR or AR glasses, the thickness of the entire module can be made in the order of centimeters or even millimeters. In the existing VR or AR optical module, the light beam generator needs to be arranged at the side of the head of the user and needs to have a certain angle to avoid the light beam being blocked by the forehead of the user, so the thickness of the whole module needs to be made larger. In the optical assembly of the present disclosure, by providing two beam combiners, the problem of forehead shielding of the user does not need to be considered, so the overall thickness can be made smaller.

In addition, the optical assembly of the present disclosure is advantageous in that the two beam combiners are disposed coaxially, and defects such as image distortion caused by the off-axis arrangement of the beam combiners and the propagation direction of the image light can be avoided.

In the optical assembly of the present disclosure, the planes of the first beam combiner and the second beam combiner are parallel to each other, and the main beam emitted from the light source is perpendicularly incident on the first beam combiner, that is, the propagation direction of the image light is coaxial with the first beam combiner and the second beam combiner. In this case, the projection surface formed on the first beam combiner and the projection surface formed on the second beam combiner are also parallel to each other. That is, the image formed on the projection surface of the second beam combiner is enlarged in three dimensions in an equal proportion to the image formed on the projection surface of the first beam combiner, and there is no stretching of the image portion, so that the distortion problem can be avoided.

In order to more clearly describe the situation of the technical scheme of the present disclosure without image distortion, the imaging process in fig. 1 is illustrated in a three-dimensional space. As shown in fig. 2, 21 is, for example, a scanning galvanometer, and the scanning area of the scanning galvanometer on the first beam combiner 22 is a rectangular area K1. Point P is the intersection of the opposite extensions of the boundary rays of light illuminated onto the first beam combiner 22 that are diffracted by the first beam combiner 22. K2 is the area where the boundary light diffracted by the first beam combiner 22 is formed on the second beam combiner 23. From the basic projection relationship, the area K2 formed by the diffracted light on the second beam combiner 23 is still a rectangular area, and the size of the area is enlarged in proportion to the rectangular area K1 scanned and formed on the first beam combiner 22. It follows that the rectangular area scanned by the scanning galvanometer is transferred proportionally to the second beam combiner 23, which is still rectangular, rather than having a stretched distorted image, thus illustrating the advantages of the present disclosure over other approaches.

Fig. 3A shows an optical assembly 30 according to a preferred embodiment of the present disclosure. Described in detail below with reference to fig. 3A.

The optical assembly 30 in fig. 3A also includes a first beam combiner 312, a light-transmissive medium 313 and a second beam combiner 314, similar to those shown in fig. 1, and will not be described again here. As shown in fig. 3A, the light beam generator 311 includes an image source 316 and a micro-electromechanical system 317, wherein the image source 316 is configured to generate a laser light beam L0 carrying color information and/or brightness information of an image pixel, the light beam L0 is incident on the micro-electromechanical system 317, and the micro-electromechanical system 317 is configured to scan the light beam L0 to form a light beam group of the light cone distribution. According to a preferred embodiment of the present disclosure, the micro-electro-mechanical system 317 comprises, for example, a MEMS galvanometer, which receives the incident light beam L0 and scans it to form the set of light beams of the light cone distribution.

In fig. 3A, the light beam L0 from the image source 316 is always on the same spatial path, but since the MEMS 317 (e.g., the MEMS galvanometer therein) can rotate and scan the light beam L0 incident thereon, the emergent light beam forms a light beam group with a light cone distribution (e.g., the light cone defined by L1 and L2 in fig. 3A).

According to a preferred embodiment of the present disclosure, the beam generator is a beamlet generator, and the image source thereof includes a plurality of lasers, a controller and a beam combiner, the controller is coupled with the plurality of lasers and controls the plurality of lasers to emit laser beams, such as controlling the light emitting time, intensity and other optical parameters of the lasers. Laser beams of the plurality of lasers are incident to the beam combiner and combined into near-parallel beamlets whose propagation paths are overlapped in space. Described in detail below with reference to fig. 3A.

As shown in fig. 3A, the image source 316 includes lasers, such as the first laser 301, the second laser 302, and the third laser 303 shown in fig. 3A, wherein the first laser 301 is, for example, a red laser, the second laser 302 is, for example, a green laser, and the third laser 303 is, for example, a blue laser, each emitting a laser beam of a corresponding wavelength. Optionally, the image source 316 further comprises a first lens (or lens group) 304, a second lens (or lens group) 305 and a third lens (or lens group) 306, which are respectively used for collimating, reducing the divergence angle, or compressing the laser beams emitted by the first laser 301, the second laser 302, and the third laser 303 upstream in the optical path, so as to form high-directivity beamlets. The beam combiner includes, for example, optical thin film beam splitters corresponding to wavelengths of laser light emitted by the plurality of lasers, and the optical thin film beam splitters are respectively disposed downstream of lenses (or lens groups) corresponding to the lasers, wherein the laser light of the lasers passes through the lens groups, then enters the corresponding optical thin film beam splitters, and is reflected or transmitted to form the near-parallel beamlets whose propagation paths coincide in space. Optionally, the beam combiner of the image source 316 includes a first light splitter 307, a second light splitter 308, and a third light splitter 309, corresponding to the red, green, and blue lasers, for combining the red, green, and blue laser beams, respectively. The first light splitter 307 is taken as an example for detailed description. The first light splitter 307 is disposed downstream of the first lens 304 in the optical path, and is, for example, an optical film segment corresponding to the wavelength of the laser light emitted from the first laser 301, so that the red light emitted from the first laser 301 is reflected and light of wavelengths other than the red light is transmitted. Similarly, the second dichroic sheet 308 causes green light emitted by the second laser 302 to be reflected and light of wavelengths other than green light to be transmitted; the third light splitter 309 allows the blue light emitted by the third laser 303 to be reflected and light of wavelengths other than blue to be transmitted. The red laser light is reflected by the first light splitter 307, incident on the second light splitter 308 and transmitted through the second light splitter 308, and then transmitted through the third light splitter 309. The green laser light is reflected by the second dichroic sheet 308, incident on the third dichroic sheet 309, and transmitted through the third dichroic sheet 309. The blue laser light is reflected by the third light splitter 309. The reflection paths of the first light splitting sheet 307, the second light splitting sheet 308, and the third light splitting sheet 309 are set to be the same as shown in fig. 3A, and therefore, the light beams reflected from the three light splitting sheets are finally combined into a light beam L0. Wherein the lens group can comprise a liquid lens or a liquid crystal lens, and the equivalent focal length of the lens group can be adjusted through external voltage control, so as to control the divergence angle and/or the diameter of the laser beam emitted by the laser. The controller may, for example, control the corresponding laser. For example, if only red and green wavelength components are present in a currently projected pixel, the first laser 301 and the second laser 302 are controlled by the controller to emit laser beams of corresponding wavelengths; and the third laser 303 is controlled by the controller to emit no laser beam.

In addition, the beam splitter may be a broadband beam splitter, which allows light in a certain wavelength range to be reflected and transmits light in other wavelength ranges.

The light beam L0 is incident on a MEMS galvanometer 317, such as an optical scanning galvanometer. The mirrors In the galvanometer are deflected back and forth within a certain angle range under the action of electromagnetic force, so that the incident light beam L0 is scanned and emitted to form a light cone-shaped light beam group, for example, a light cone defined by the reflected light beams L1 and L2 at different times, wherein the vertex of the light cone, for example, the swing center of the galvanometer, is located at the position of the entrance pupil 10-In of the optical assembly 30. Further, according to a preferred embodiment of the present disclosure, the galvanometer 317 and the first and

second beam combiners

312 and 314 are arranged such that: the beams produced by the galvanometers at their scan limits (e.g., beams L1 and L2) may each be incident on the first beam combiner 312 and propagate through the optically transparent medium 313 before being incident on the second beam combiner 314. And will not be described in detail herein.

Additionally, in accordance with a preferred embodiment of the present disclosure, the image source 316 may further include one or more of a diaphragm, a wave plate, a polarizing plate, an attenuation plate (not shown) disposed between the lenses (or lens groups) 304, 305, 306 and the

optical film splitters

307, 308, 309. The image source 316 may also include a micro-motor (not shown) coupled to the lens (or lens group) that can adjust the position of the lens (or lens group), or adjust the relative position between lenses in a lens group, to adjust optical parameters such as the spot size and/or divergence angle of the light beam exiting the lens group.

Those skilled in the art will readily understand that the wavelengths and intensities of the laser beams emitted by the first laser 301, the second laser 302 and the third laser 303, for example, the three RGB wavelength components corresponding to one pixel of a picture or pattern, respectively transmit laser beams with corresponding wavelengths, and then combine the laser beams.

Those skilled in the art will readily appreciate that the image source 316 is schematically illustrated in fig. 3A as including three lasers of red, green, and blue, although the scope of the present disclosure is not limited in this respect. For example, the image source 316 may include a greater or lesser number of lasers, and the wavelengths of the lasers may be selected as desired. For example, the image source 316 may include only one laser emitting a monochromatic laser, all within the scope of the present disclosure.

In addition, the scope of the present disclosure is not limited to the type of optical field emitted by the laser. The laser emits either a plane wave or a spherical wave, which is collimated and compressed by a lens or a set of lenses, as will be readily understood by those skilled in the art.

In the embodiment of fig. 3A, the beam generator 311 further comprises a mirror 310. In this case, the light beam L0 is first incident on the mirror 310 and then reflected by the mirror 310 to the mems 317. Such an arrangement is advantageous to further reduce the thickness of the entire optical module.

Fig. 3B illustrates an optical assembly 30 according to another embodiment of the present disclosure. As shown in fig. 3B, the optical assembly 30 includes a first beam combiner 312, a transparent medium 313 and a second beam combiner 314, which are the same as those described in fig. 1 and 3A and are not repeated herein. In fig. 3B, the optical assembly 30 further includes a light beam generator 311, and the light beam generator 311 includes, for example, a light source 3111, a lens 3112, and a display 3113 arranged in sequence. The light source 3111 is, for example, a monochromatic laser light source, a multicolor laser light source (e.g., red, green, and blue lasers), or an LED light source or an OLED light source for providing illumination or backlight for the display panel 3113. When a laser light source, for example, a light source coupled into an optical fiber is used, divergent illumination light is emitted from a fiber head, and light emitted from the light source 3111 is incident on the lens 3112, modulated by the lens 3112, and converged at a position of the entrance pupil 10-In, thereby forming the light cone-shaped beam group. The display screen 3113, which may be one or more of a DMD, LCoS, and LCD, for example, is disposed between the lens 3112 and the entrance pupil 10-In. The display screen 3113 itself may be loaded with an image and modulate light irradiated thereto from the lens 3112 according to information of color and/or brightness of the loaded image. Thus, the light beam groups exiting through the display screen 3113 are not only converged to the entrance pupil 10-In, but also carry color information and/or brightness information for different image pixels.

Or alternatively, as shown In fig. 3C, a display screen 3113 (such as one or more of DMD, LCoS, LCD) may be disposed between the light source 3111 and the lens 3112, the light emitted from the light source 3111 is directly irradiated onto the display screen 3113, the display screen 3113 modulates the light beam irradiated thereon according to the information of the color and/or brightness of the loaded image, and the modulated light beam passes through the lens 3112 and is converged at the position of the entrance pupil 10-In, thereby forming the light beam group of the light cone distribution. And will not be described in detail herein.

Alternatively, one skilled in the art can also conceive that the same effect can be achieved without the need for the lens 3112 by illuminating the display with a surface light source or using the same point light source as in fig. 3C and placing a diffuser film behind the point light source, so that the light emitted from the display has various directions, placing an aperture stop at the entrance pupil position of the assembly, and forming a beam set of light cones from the light emitted from the display after passing through the aperture stop.

The embodiment shown in fig. 3 employs a combination of a first beam combiner of the transmissive type and a second beam combiner of the reflective type. Fig. 4 to 6 show embodiments employing a combination of a transmissive first beam combiner and a transmissive second beam combiner, a combination of a reflective first beam combiner and a transmissive second beam combiner, and a combination of a reflective first beam combiner and a reflective second beam combiner, respectively.

As previously described, the first beam combiner 12 and the second beam combiner 14 each include, for example, a diffractive optical element, such as a volume holographic optical element, either a transmissive volume holographic optical element or a reflective volume holographic optical element. As will be described in detail below.

According to a preferred embodiment of the present disclosure, the volume hologram optical element is a single color volume hologram optical element, for example, a single color volume hologram optical film, which is obtained by exposing laser beams with wavelengths corresponding to the plurality of lasers, for example, so that the laser beams with the corresponding wavelengths emitted by the plurality of lasers can be diffracted and modulated correspondingly. For example, when a single color volume holographic optical film sensitive to red, green, and blue lasers is used in the optical assembly of the embodiment of fig. 3A, the color volume holographic optical film can diffract and modulate the incident beam to converge on a point outside the light-transmitting medium, whether the incident beam is red, green, blue, or a combination of a plurality thereof. The single color volume hologram optical film may be obtained by simultaneous exposure with the laser beams of the plurality of lasers, or may be obtained by performing successive exposure a plurality of times each time with a laser beam of one wavelength. The method has the advantages that a plurality of volume holographic optical films do not need to be aligned and stacked together, and the setting mode is simple.

Or alternatively, the volume hologram optical element includes a plurality of monochromatic volume hologram optical elements aligned exactly and stacked together, corresponding to the number of the plurality of lasers, each of the plurality of monochromatic volume hologram optical elements being obtained by exposure to laser light of a wavelength corresponding to one of the plurality of lasers. For example, when three sheets of solid-state holographic optical films sensitive to red, green, and blue laser light are used in the optical assembly of the embodiment of fig. 3A, the solid-state holographic optical films sensitive to red laser light diffract only the red laser light and do not diffract the laser light of other wavelengths, so that the red laser beams incident thereon at different angles continue to propagate at different angles after being subjected to diffraction modulation by the films (under the diffraction action of the first beam combiner, the red laser beams enter the light-transmitting medium to continue to propagate; under the diffraction action of the second beam combiner, the red laser beams enter the free space to continue to propagate). The monochromatic volume holographic optical film sensitive to the green laser and the monochromatic volume holographic optical film sensitive to the blue laser are similar to the diffraction condition of the monochromatic volume holographic optical film sensitive to the red laser to the corresponding wavelength light wave. Those skilled in the art will readily appreciate that if more wavelengths of lasers are included in the light source, the beam combiner may also include a corresponding volume holographic optical film. All of which are within the scope of the present disclosure. The advantage of this approach is that each volume holographic optical element is only exposed once, and the diffraction efficiency is high, but this approach has a high requirement for the alignment accuracy when multiple volume holographic optical elements are stacked. The laser used for exposure is, for example, a single longitudinal mode laser, and has strong coherence. The laser used as the display light source may be a multimode laser of low coherence, or an LED or OLED light source of corresponding wavelength. When the optical film is used, the first beam combiner and/or the second beam combiner which comprises three monochromatic volume holographic optical films sensitive to red, green and blue laser is/are directly attached to the corresponding surfaces of the light-transmitting medium, and then the diffraction modulation effect on the beams with various wavelengths incident on the light-transmitting medium can be realized.

Or alternatively, the volume holographic optical element comprises a plurality of volume holographic optical elements that are precisely aligned and stacked together, the number of the plurality of volume holographic optical elements being less than the number of the plurality of lasers, at least one of the plurality of volume holographic optical elements being obtained by laser exposure of at least two of the plurality of lasers, the remaining volume holographic optical elements being obtained by laser exposure of a remaining one of the plurality of lasers. For example, on the basis of the above-described embodiment using three sheets of the monochromatic volume holographic optical films sensitive to red, green and blue lasers, a sheet of the volume holographic optical film sensitive to red and green at the same time is used instead of the monochromatic volume holographic optical film sensitive to red laser and the monochromatic volume holographic optical film sensitive to green laser. The volume holographic optical film sensitive to red and green simultaneously is obtained, for example, by simultaneous or sequential exposure with red and green lasers. Alternatively, a sheet of volume holographic optical film sensitive to both green and blue may be used instead of the monochromatic volume holographic optical film sensitive to green laser and the monochromatic volume holographic optical film sensitive to blue laser; or a sheet of volume holographic optical film sensitive to both red and blue may be used instead of the monochromatic volume holographic optical film sensitive to red laser light and the monochromatic volume holographic optical film sensitive to blue laser light. All of which are within the scope of the present disclosure. This arrangement improves diffraction efficiency while reducing the number of times of stacking, relative to the arrangement of the above-described embodiments that all employ a single-color volume holographic optical element.

Alternatively, the volume hologram optical element includes a sheet of monochromatic volume hologram optical element corresponding to a laser beam of one wavelength and a laser.

It should be noted that the structures and forms of the diffractive optical elements included in the first beam combiner and the second beam combiner can be independently selected from the different manners described in the above embodiments (for example, a single color volume holographic optical element, or a plurality of monochromatic volume holographic optical elements corresponding to the number of lasers, or a plurality of individual holographic optical elements less than the number of lasers, or a single monochromatic volume holographic optical element), and both can be the same or different. All of which are within the scope of the present disclosure.

In a preferred embodiment of the present disclosure, as shown in fig. 7, the first beam combiner 72 includes three monochromatic volume holographic optical films, a first volume holographic optical film 721 (sensitive to red), a second volume holographic optical film 722 (sensitive to green), and a third volume holographic optical film 723 (sensitive to blue), which respectively perform diffraction modulation on beams of different wavelengths. The second beam combiner 74 includes three monochromatic volume hologram optical films, a fourth volume hologram optical film 741 (sensitive to red), a fifth volume hologram optical film 742 (sensitive to green), and a sixth volume hologram optical film 743 (sensitive to blue), which respectively perform diffraction modulation on light beams having different wavelengths. Taking the first volume holographic optical film 721 and the fourth volume holographic optical film 741 of red component as an example, only the red laser beam is diffracted and the laser beams of other wavelengths are not diffracted, so that the red laser beam incident thereon at different angles enters the light-transmitting medium 73 at different angles after being modulated by the diffraction of the first volume holographic optical film 721 and continues to propagate, and enters the free space at different angles after being modulated by the diffraction of the fourth volume holographic optical film 741 and continues to propagate, wherein the light beams propagating in the free space in different directions are converged at the exit pupil position. Similarly, the second volume holographic optical film 722 and the fifth volume holographic optical film 742 for the green color component diffract only the green laser light and do not diffract the laser light with other wavelengths, so that the green laser beams incident thereon at different angles enter the light-transmitting medium 73 for continuous propagation at different angles after being modulated by the diffraction of the second volume holographic optical film 722, and enter the free space for continuous propagation at different angles after being modulated by the diffraction of the fifth volume holographic optical film 742, wherein the beams in different directions propagating in the free space are converged at the exit pupil position. Similarly, the third volume hologram optical film 723 and the sixth volume hologram optical film 743 for the blue component diffract only blue laser light and do not diffract laser light of other wavelengths, so that blue laser beams incident thereon at different angles enter the light-transmitting medium 73 to continue propagating at different angles after being modulated by the diffraction of the third volume hologram optical film 723, and continue propagating in a free space at different angles after being modulated by the diffraction of the sixth volume hologram optical film 743, wherein beams propagating in the free space in different directions are converged at the exit pupil position.

According to one embodiment of the present disclosure, the volume hologram optical element is obtained by exposing a film of a photosensitive material or a photosensitive plate in which a photosensitive material is attached to a glass substrate or a resin substrate in such a manner that the photosensitive material includes one or more of a silver salt material, a photopolymer material, and a gelatin material, and the photosensitive material can sense one or more of red light, green light, or blue light. As will be described in detail below.

Fig. 3 to 6 respectively show the technical solutions that the first beam combiner uses a reflective or transmissive volume hologram optical element and the second beam combiner uses a reflective or transmissive volume hologram optical element. The person skilled in the art will readily understand that the features of any of these solutions can be combined into another solution without the need for inventive effort.

The first aspect of the present disclosure also relates to a display system comprising an optical assembly as described above. The display system is, for example, a virtual reality display system or an augmented reality display system.

According to one embodiment of the present disclosure, the display system further comprises an image generation unit configured to generate an image to be displayed, the image generation unit being coupled to the light beam generator, the light beams of different directions in the group of light beams emitted by the light beam generator carrying color information and/or brightness information of different pixels in the image.

The image generation unit is for example used to generate images that need to be presented to a user. The beam generator scans the image, e.g. pixel by pixel, generating a respective laser beam from the red, green and blue components of each pixel, wherein color information and/or brightness information of different pixels in the image is carried. The display system projects the light beam of the pixel through the optical assembly into the eye of the user (e.g., onto the retina) to image in the eye of the user. Preferably, the display system comprises two sets of the optical assemblies, and the same two-dimensional images are respectively displayed for the left eye and the right eye of the user for two-dimensional display or the two-dimensional images with parallax are used for realizing three-dimensional display based on binocular parallax. Because the method disclosed by the invention is retina imaging, the depth of field of the image is large and the problem of convergence regulation conflict is avoided for the binocular parallax three-dimensional display.

The first aspect of the present disclosure also relates to an image projection method 80 of an optical system. As shown in fig. 8, the image projection method 80 includes:

step S81: generating a light beam group with light cone distribution;

step S82: the light beam group distributed by the light cone is incident to a first light beam synthesizer on one surface of a light-transmitting medium, and the propagation direction of the light beam incident to the first light beam synthesizer is changed by the first light beam synthesizer so that the light beam enters the light-transmitting medium at different angles to be propagated continuously;

step S83: and changing the propagation direction of the beams which propagate in the light-transmitting medium and are incident on the second beam combiner by a second beam combiner on the other parallel surface of the light-transmitting medium, so that the beams leave the second beam combiner at different angles to continue to propagate, wherein the beams from the beam group with the same light cone distribution converge after leaving the second beam combiner.

The method 80 may be implemented, for example, by the optical assembly described above, or by an optical system having the optical assembly described above.

The optical system is provided with an entrance pupil and an exit pupil, the vertex of the light cone is the entrance pupil, and the point, which is converged after the light beams from the light beam group with the same light cone distribution leave the second light beam synthesizer, is the exit pupil.

According to a preferred embodiment of the present disclosure, the light beam generator includes a light source and a micro electro mechanical system, as shown in fig. 3A, wherein the step S81 includes:

s811: emitting a light beam carrying color information and/or brightness information of an image pixel by using a light source;

s812: and scanning the light beams emitted from the light source by using a micro-electro-mechanical system to form a light beam group with the light cone distribution.

According to a preferred embodiment of the present disclosure, as shown in fig. 3C, the step S81 includes:

s813: a light source is used for emitting illumination light to irradiate a display screen, wherein the light source is a monochromatic or three-color laser light source or an LED light source or an OLED light source, and the display screen is a DMD, an LCoS or an LCD;

s814: loading an image into the display screen, and modulating light irradiated onto the display screen by the light source according to the image;

s815: the modulated light is shaped into a beam group of the light cone distribution by means of a diaphragm or a lens.

According to a preferred embodiment of the present disclosure, as shown in fig. 3B, the step S81 includes:

s816: a light source is used for emitting illumination light, the illumination light irradiates a lens and is converged to the vertex of the light cone through the lens, wherein the light source is a monochromatic or three-color laser light source or an LED light source or an OLED light source;

s817: the light beams passing through the lens irradiate a display screen between the lens and the vertex, the display screen is a DMD, an LCoS or an LCD, and the display screen loads images and modulates the light beams irradiated on the display screen from the lens according to the images.

It should be understood that the foregoing various exemplary display systems may be configured in two sets, which respectively provide images for the left eye and the right eye of a human, and if the images displayed by the left eye and the right eye include image information of binocular parallax, three-dimensional display of binocular parallax may be achieved; if the images displayed by the left and right eyes are ordinary two-dimensional images, ordinary two-dimensional display can be realized. It should be appreciated that the display system implements a display technology that is retinal imaging, and that the three-dimensional display that implements reduces or eliminates the convergence conflict problem.

Further, the beam combiner in the optical assembly of the present disclosure is conceived and designed, for example, to avoid defects such as image distortion caused by the off-axis arrangement of the propagation direction of the image light and the beam combiner.

It should be appreciated that the foregoing various exemplary methods may be implemented in various ways, for example, in some embodiments, the foregoing various methods may be implemented using software and/or firmware modules, as well as hardware modules. Other ways, now known or later developed, are also possible, and the scope of the present disclosure is not limited in this respect. In particular, embodiments of the present disclosure may be implemented in the form of a computer program product, in addition to hardware embodiments.

Second aspect of the invention

The above describes an optical assembly according to the first aspect of the present disclosure, which includes a first beam combiner, a light-transmitting medium, and a second beam combiner, respectively attached to two parallel surfaces of the light-transmitting medium, for changing the propagation direction of the light beam incident thereon, for example, so that the incident light beams from the same light cone continue to propagate and converge on a point after leaving the second beam combiner. Those skilled in the art will readily appreciate that the beam combiner may be fabricated and implemented in a variety of ways. A particularly preferred manner of manufacture, found by the inventors of the present application, is described below, particularly suitable for manufacturing beam combiners or volume holographic optical elements suitable for use in the optical assemblies of the first aspect of the present disclosure.

A second aspect of the present disclosure relates to a method of manufacturing an optical element, as shown in fig. 9 and 10.

Fig. 9 shows a method 90 of manufacturing an optical element according to the second aspect of the present disclosure. Fig. 10 shows a schematic optical path diagram for fabricating the first beam combiner and the second beam combiner by the fabrication method 90. As described in detail below in conjunction with fig. 9 and 10.

As shown in fig. 9, the manufacturing method 90 includes:

step S91: providing a light-transmitting medium, wherein the light-transmitting medium is provided with two surfaces which are parallel to each other, and a first photosensitive film/photosensitive plate and a second photosensitive film/photosensitive plate are respectively attached to the surfaces.

As shown in fig. 10, the light-transmitting medium 1024 has upper and lower surfaces parallel to each other, wherein the lower surface is attached with a first photosensitive film/plate 1018, and the upper surface is attached with a second photosensitive film/plate 1022. The second photosensitive film/plate 1022 has a width larger than that of the first photosensitive film/plate 1018, for example. The light-transmissive medium 1024 may be, for example, the same as the light-transmissive medium shown in fig. 1 to 7, or have at least partially the same optical and/or geometric parameters.

Step S92: laser light is emitted by a laser.

Fig. 10 shows three

lasers

1001, 1002 and 1003, for example a red laser 1003, a green laser 1002 and a blue laser 1001, respectively. Those skilled in the art will readily understand that the three lasers shown in fig. 10 are merely illustrative, and the number and wavelength thereof do not limit the present disclosure, and that a smaller number of lasers may be used, or a larger number of lasers may be used, all of which are within the scope of the present disclosure. Three lasers will be described as an example.

After the three

lasers

1001, 1002, and 1003 emit laser beams with different wavelengths, the laser beams with the three wavelengths are combined by the beam combiner to combine the laser beams with the three wavelengths into a high-directivity beamlet. According to a preferred embodiment, the beam combiner includes a first light splitter 1004, a second light splitter 1005, and a third light splitter 1006. The first light splitter 1004 will be described in detail below as an example. The first light splitting sheet 1004 is disposed downstream of the laser 1001 in the optical path, and is, for example, an optical thin film light splitting sheet corresponding to the wavelength of the blue laser light emitted from the laser 1001, so that the blue light emitted from the laser 1001 is reflected and light having wavelengths other than the blue light is transmitted. Similarly, a second dichroic sheet 1005 is positioned optically downstream of laser 1002 such that green light emitted by laser 1002 is reflected and light of wavelengths other than green is transmitted; a third light splitter 1006 is positioned in the optical path downstream of the laser 1003 such that red light emitted by the laser 1003 is reflected and light of wavelengths other than red is transmitted. The reflection paths of the first, second and third

light splitters

1004, 1005 and 1006 are arranged to be the same, as shown in FIG. 10, whereby the light beams reflected from the three light splitters eventually combine to form a highly directional beamlet L00.

According to a preferred embodiment of the present disclosure, the combined laser beam is filtered, collimated and expanded. As shown in fig. 10, the combined laser beam is incident on the microscope objective and pinhole filter 1007, and the high-directivity beamlets are converged at a high power on the pinholes for filtering, thereby emitting high-quality spherical waves, and then incident on the collimator lens 1008. Here, the pinhole filter 1007 is located at the focal plane of the collimator lens 1008, and thus the light wave emitted from the pinhole filter 1007 is converted into a laser beam L10 of a high-quality plane wave after passing through the collimator lens 1008.

Step S93: the laser light is split into a first laser beam and a second laser beam.

As shown in fig. 10, the beam splitting may be performed by a first beam splitter 1009, for example, which is a half-reflecting and half-transmitting film, so that the beam incident thereon is partially reflected, partially transmitted, and split into a first laser beam L11 and a second laser beam L22, and the first laser beam L11 and the second laser beam L22 are derived from the same laser beam, and thus have strong coherence.

Step S94: splitting the first laser beam into a third laser beam and a fourth laser beam.

As shown in fig. 10, the beam splitting may be performed by a second beam splitter 1011, for example, a half-reflecting and half-transmitting film, so that the beam incident thereon is partially reflected, partially transmitted, and split into a third laser beam L31 and a fourth laser beam L32, and the third laser beam L31 and the fourth laser beam L32 are derived from the same laser beam, and thus have strong coherence.

According to a preferred embodiment of the present disclosure, the first laser beam L11 is attenuated before splitting. As shown in fig. 10, since the first photosensitive film/plate 1018 has a smaller width than the second photosensitive film/plate 1022, the first laser beam L11 may be appropriately condensed before being incident on the first photosensitive film/plate 1018 to better match the size of the first photosensitive film/plate 1018. The beam reduction can be realized, for example, by means of an aperture 1010, which is blocked by means of the aperture 1010, and through which only a spot of a certain size is passed, thereby obtaining a reduced beam L30. The laser beam L30 is split into a third laser beam L31 and a fourth laser beam L32 by the second beam splitter 1011.

Step S95: and converging the third laser beam to a first point outside the light-transmitting medium, and emitting the third laser beam from the first point to the first photosensitive film/photosensitive plate.

As shown in fig. 10, the third laser beam L31 passes through the first lens 1012 and converges at a first point 1013, for example, a point at the focal point or focal plane of the first lens 1012, to form a cone beam, and is incident on the first photosensitive film/plate 1018. The first lens 1012 is only one implementation of converging the third laser beam L31 to the first point 1013, and the scope of the present disclosure is not limited thereto, and other ways of converging the third laser beam L31 to the first point 1013 are contemplated.

Step S96: and converging the fourth laser beam to a second point outside the light-transmitting medium, and emitting the fourth laser beam from the second point to the first photosensitive film/photosensitive plate.

As shown in fig. 10, the fourth laser beam L32 passes through the first mirror 1014, the second mirror 1015, and the second lens 1016 and converges to a second point 1017, e.g., a point on the focal point or focal plane of the second lens 1016, forming a cone beam and incident on the first photosensitive film/plate 1018. The first mirror 1014, the second mirror 1015 and the second lens 1016 are just one implementation of converging the fourth laser beam L32 to the second point 1017, and the scope of the disclosure is not limited thereto, and other ways of converging the fourth laser beam L32 to the second point 1017 are contemplated.

Step S97: and the third laser beam converged to the first point and the fourth laser beam converged to the second point generate interference exposure in the photosensitive material of the first photosensitive film/photosensitive plate, and the first integral holographic optical element can be obtained through subsequent treatment.

As shown in fig. 10, the third laser beam converged to the first point 1013 is a signal light, and the fourth laser beam converged to the second point 1017 is a reference light, and the signal light and the reference light are subjected to interference exposure inside the first photosensitive film/photosensitive plate 1018, thereby obtaining a first volume hologram optical element.

Step S98: and enabling the fourth laser beam to pass through the first photosensitive film/photosensitive plate, enter the inside of the light-transmitting medium and be incident on the second photosensitive film/photosensitive plate.

As shown in fig. 10, the fourth laser beam L32 incident on the first photosensitive film/plate 1018 passes through the first photosensitive film/plate 1018, continues to propagate inside the translucent medium 1024, and is incident on the second photosensitive film/plate 1022.

Step S99: and converging the second laser beam to a third point outside the light-transmitting medium after the second laser beam passes through the second photosensitive film/photosensitive plate.

As shown in fig. 10, the second laser beam L22 passes through the third mirror 1019, the fourth mirror 1020 and the third lens 1021 and converges to the third point 1023. It will be readily understood by those skilled in the art that the third point 1023 is not necessarily the focal point of the third lens 1021 or located at the focal plane, because the second laser beam L22 may be refracted while passing through the second photosensitive film/plate 1022 and/or the light-transmitting medium 1024, and thus the converging third point 1023 may be located in front of or behind the focal point or focal plane of the third lens 1021. Furthermore, it is easily understood by those skilled in the art that the third mirror 1019, the fourth mirror 1020 and the third lens 1021 are only one implementation manner for converging the second laser beam L22 to the third point 1023, and the scope of the present disclosure is not limited thereto, and other manners for converging the second laser beam L22 to the third point 1023 are conceivable.

Step S100: and the fourth laser beam which passes through the first photosensitive film/photosensitive plate and enters the light-transmitting medium and the second laser beam converged to the third point generate interference exposure in the photosensitive material of the second photosensitive film/photosensitive plate to obtain a second volume holographic optical element.

As shown in fig. 10, the fourth laser beam L32 passing through the first photosensitive film/plate 1018 and entering the transparent medium 1024 is a signal beam, the second laser beam L22 converged at the third point 1023 is a reference beam, the signal beam and the reference beam undergo interference exposure inside the second photosensitive film/plate 1022, and the second volume hologram optical element can be obtained after subsequent processing.

In the above fabrication path, the multiple lasers are combined and then expanded, and then split for exposure, as will be readily understood by those skilled in the art. However, the light emitted from the multiple lasers may be expanded and then combined by the reflector and the beam combining and splitting plate to form a mixed planar wave for subsequent exposure, and both implementations will be obvious to those skilled in the art and should be considered as within the scope of the present disclosure.

In the embodiment shown in fig. 10, the fourth laser beam L32 is incident on the first photosensitive film/plate 1018 at an angle of inclination with respect to a cone beam after converging to the second point 1017. In actual operation, there may be a case where the inclination angle is large and it is difficult to implement. For ease of description and illustration, the parameter "included angle α" is introduced herein, and is defined as the angle between the principal ray direction of the cone beam formed by the fourth laser beam after converging to the second point outside the light-transmitting medium and the vertical axis of the first photosensitive film/plate, as shown in fig. 10.

When the included angle α is too large to be implemented, according to a preferred embodiment of the present disclosure, referring to fig. 11A, a wedge prism 111 may be added below the first photosensitive film/plate 1018 based on the scheme of fig. 10. The wedge prism 111 has a trapezoidal or similar longitudinal cross section, and the fourth laser beam L32 passes through the side surface S1113 and the bottom surface S1112 of the wedge prism 111 in this order and is incident on the first photosensitive film/plate 1018. Since the side surface S1113 of the wedge prism 111 is provided with a slope, the fourth laser beam L32 is refracted while passing through the surface, thereby allowing the fourth laser beam L32 to be incident at a relatively reduced angle α. On the other hand, the third laser beam L31 passes through the upper surface S1111 and the lower surface S1112 of the wedge prism 111 in sequence and then enters the first photosensitive film/photosensitive plate 1018, and both the upper surface S1111 and the lower surface S1112 are disposed parallel to the first photosensitive film/photosensitive plate 1018, so as to ensure that the optical path of the third laser beam L31 is not affected when passing through the wedge prism 111.

In accordance with a preferred embodiment of the present disclosure, when the first photosensitive film/plate 1018 is fabricated as a reflective volume hologram optical element (e.g., as shown in fig. 5 and 6), a wedge prism 112 may be added above the first photosensitive film/plate 1018, thereby reducing an angle α between the fourth laser beam L32 and a vertical axis of the first photosensitive film/plate 1018 when incident thereon. Here, more preferably, the wedge prism 112 may be provided with a triangular longitudinal section as shown in fig. 11B, in which the side surface S1122 is provided with a slope so that the fourth laser beam L32 is refracted while passing through the surface; and the lower surface S1121 is disposed in parallel with the first photosensitive film/plate 1018, thereby ensuring that the optical path of the third laser beam L31 is not affected. When the longitudinal section of the wedge prism is triangular, there are advantages such as easy processing to save cost and convenient practical operation, compared with the case where the longitudinal section is trapezoidal.

In other words, if the angle at which the fourth laser beam directly enters the first photosensitive film/photosensitive plate without using the wedge prism is α 1 (if the angle is large, the incident direction is too "flat" and is difficult to implement), it is only necessary to consider that the fourth laser beam enters the wedge prism at a reduced angle α 2 (the incident direction is "vertical" and is easy to implement), and the fourth laser beam can enter the first photosensitive film/photosensitive plate at the same angle α 1 after being refracted by the wedge prism.

According to a preferred embodiment of the present disclosure, the step S97 and the step S100 are performed simultaneously. That is, the first photosensitive film/plate 1018 and the second photosensitive film/plate 1022 are simultaneously exposed.

The first and second photosensitive films/

plates

1018, 1022 may be used in the optical assembly of the first aspect of the present disclosure after exposure to light for modulating one or more incident light beams of a particular wavelength. Those skilled in the art will readily understand that the wavelength of the laser emitted by the laser in step S92 may be the same as or similar to the corresponding wavelength in the display. Those skilled in the art will appreciate that wavelengths that differ by less than 20nm may be referred to as being similar. For example, the wavelength of the red laser 1003 in fig. 10 is the same as or similar to the first laser 301 in fig. 3A, the wavelength of the green laser 1002 in fig. 10 is the same as or similar to the second laser 302 in fig. 3A, and the wavelength of the blue laser 1001 in fig. 10 is the same as or similar to the third laser 303 in fig. 3A. It can be understood by those skilled in the art that when the display scheme of the present invention is implemented by using LCoS or DMD as the display device, the implemented color display is a time-sequential color display, the wavelength range of the red, green, blue LEDs or OLEDs used should be included in the wavelength range of the laser used in the exposure of the first photosensitive film/photosensitive plate 1018 and the second photosensitive film/photosensitive plate 1022, and due to the wavelength selectivity of the volume holographic optical element, the red, green, blue LEDs or OLEDs having a wide wavelength range can be displayed by the first photosensitive film/photosensitive plate 1018 and the second photosensitive film/photosensitive plate 1022, and only the light having the wavelength satisfying the bragg condition is diffracted, so that the color saturation of the displayed image is high. It can be understood by those skilled in the art that when the LCD is used as a display device to implement the display scheme of the present invention, the LCD is coated with color filters, and the displayed colors are displayed simultaneously, instead of a time-sequential color display scheme, light of red, green, and blue LEDs or OLEDs may be used for illumination after beam combining, and white LEDs or OLEDs may also be used for illumination, and the light after passing through the color filters carries color and intensity information of an image, and the bandwidth of light waves of each color is large, and a certain wavelength selection can still be performed by the implemented beam combiner during final imaging, so as to implement a color display effect with high saturation.

In addition, those skilled in the art will readily understand that the photosensitive film or plate after the interference exposure in steps S97 and S100 may need to undergo some subsequent processing. For example, for the photo-polymer material, it needs to go through the following processing steps of ultraviolet light curing, thermal curing, etc. The scope of the present disclosure is not limited to the subsequent processing steps.

The exposed first and second photosensitive films/

plates

1018 and 1022 may be used as the first and second beam combiners in the optical assembly according to the first aspect of the present disclosure, but the scope of the present disclosure is not limited thereto. The laser used for the exposure is, for example, a single longitudinal mode laser, and has strong coherence. When used in the optical assembly, the laser used as the display light source may be a multimode laser of low coherence, or an LED or OLED light source of corresponding wavelength, or a white LED or OLED.

It will be readily understood by those skilled in the art that when the first photosensitive film/plate 1018 and the second photosensitive film/plate 1022 are used in the optical assembly of the first aspect of the present disclosure, the light-transmissive medium in the optical assembly may be identical to the light-transmissive medium 1024 used in fabricating the first photosensitive film/plate 1018 and the second photosensitive film/plate 1022, and the point 1013, for example, corresponds to the entrance pupil of the optical assembly, so as to ensure that the light beams in the form of cones are incident on the second beam combiner after entering the light-transmissive medium, and can be diffraction-modulated and then converged to the exit pupil of the optical assembly. Alternatively, the transparent medium in the optical assembly may not be identical to the transparent medium 1024 used in fabricating the first photosensitive film/plate 1018 and the second photosensitive film/plate 1022, but may have at least partially the same optical and/or set parameters, so as to ensure that the illumination direction incident on the second beam combiner at different positions after the light cone-shaped light beam enters the transparent material is the same as or similar to the direction incident on the second photosensitive film/plate 1022 when fabricating the first photosensitive film/plate 1018 and the second photosensitive film/plate 1022, and the illumination direction can be diffraction-modulated and then converged to the exit pupil of the optical assembly. For this reason, the physical parameters of the light-transmitting medium used for recording and the physical parameters of the light-transmitting medium used for display may be different. For example, the optically transmissive medium in the optical assembly may be configured such that: the angle of the light beam incident on each point of the second beam combiner attached thereto is the same as the angle of the light beam propagating inside the light-transmitting medium 1024 and incident on the point of the second light-sensing film/plate 1022 when the first light-sensing film/plate 1018 and the second light-sensing film/plate 1022 are fabricated. This ensures that the light-transmitting medium and the first and second beam combiners in the optical assembly can modulate the incident light beam appropriately.

According to a preferred embodiment of the present disclosure, the photosensitive material on the first photosensitive film/plate 1018 and the second photosensitive film/plate 1022 is a full-color photosensitive material. Step S92 includes: a plurality of lasers are utilized to emit laser beams with different wavelengths, and the laser beams are emitted after being combined; steps S97 and S100 each include: and simultaneously performing interference exposure inside the photosensitive material corresponding to different wavelengths of the plurality of lasers. In this way, a full-color volume hologram optical element can be formed by one exposure.

According to an alternative embodiment of the present disclosure, the photosensitive material on the first and second photosensitive films/

plates

1018 and 1022 is a full-color photosensitive material. Step S92 includes: sequentially emitting laser beams with different wavelengths by using a plurality of lasers and emitting the laser beams; steps S97 and S100 each include: a plurality of interference exposures are successively performed inside the photosensitive material corresponding to different wavelengths of the plurality of lasers. For example, in the optical path diagram shown in fig. 10, a blue laser beam is first emitted by the blue laser 1001, and exposure is performed once in the photosensitive materials on the first photosensitive film/plate 1018 and the second photosensitive film/plate 1022; then, the green laser 1002 is caused to emit a green laser beam, and primary exposure is performed in the photosensitive material on the first photosensitive film/photosensitive plate 1018 and the second photosensitive film/photosensitive plate 1022; then, the red laser 1003 is caused to emit a red laser beam, and exposure is performed again in the photosensitive material on the first photosensitive film/photosensitive plate 1018 and the second photosensitive film/photosensitive plate 1022. After the three exposures, a full-color volume hologram optical element can be formed.

plates

1018 and 1022 is a monochromatic photosensitive material, such as sensitive only to red light. In this case, step S92 includes: emitting laser beams with the wavelength corresponding to the monochromatic photosensitive material by using a laser and emitting the laser beams; steps S97 and S100 each include: and carrying out interference exposure in the photosensitive material corresponding to the wavelength of the laser to obtain the volume holographic optical element corresponding to the wavelength. The volume hologram optical element thus formed is a monochromatic volume hologram optical element.

According to a preferred embodiment of the present disclosure, after one single-color volume holographic optical element is formed, the photosensitive film/plate that can expose light of different wavelengths may be replaced, and a plurality of volume holographic optical elements corresponding to the different wavelengths may be obtained through the aforementioned steps S92 to S100. For example, after the red volume hologram optical element is formed, the photosensitive film/plate sensitive to blue light is replaced, laser light is emitted from a blue laser and exposure is performed, a blue volume hologram optical element is formed, and then a green volume hologram optical element is formed. The monochromated holographic optical element formed in this way can be used alone or in a stack aligned and used as a beam combiner in the optical assembly of the first aspect of the disclosure.

In the optical path diagram shown in fig. 10, the volume hologram optical element finally formed is a combination of a transmissive first volume hologram optical element and a reflective second volume hologram optical element. The manufacturing method 90 of the present disclosure can also be used to form a combination of a transmissive first volume holographic optical element and a transmissive second volume holographic optical element (corresponding to fig. 4), a combination of a reflective first volume holographic optical element and a transmissive second volume holographic optical element (corresponding to fig. 5), a combination of a reflective first volume holographic optical element and a reflective second volume holographic optical element (corresponding to fig. 6), which are in principle communicated.

In addition, those skilled in the art can understand that a concave lens may be disposed between the beam generator and the first beam combiner in the manufacturing process, and the same concave lens is used in displaying, so that the field angle can be expanded in the case that the scanning angle of the MEMS galvanometer is small, and these changes are also within the protection scope of the present disclosure.

In addition, as can be understood by those skilled in the art, the second point 1017 of fig. 10 from which the fourth laser beam exits is not actually the same point as the point P in fig. 2 due to the presence of medium surface refraction, and the relationship is as follows: the second point 1017 is an equivalent point where the light converged to the point P is refracted at the surface of the first beam combiner and the free space; that is, the point P is the intersection point of the light emitted from the point 1017 and the refracted reverse extension line at the surface of the free space. In the above-described embodiments, the process of refraction between the first beam combiner and free space is not shown for simplicity of description and drawing.

In addition, it can be understood by those skilled in the art that the angle at which the light is coupled into the light-transmitting medium using the wedge prism in the above-described manufacturing process may satisfy the condition of total reflection occurring at one surface of the light-transmitting medium in contact with air or the condition of total reflection occurring at one surface of the light-transmitting medium in contact with air. In order to ensure that the second beam combiner has a certain size when the total reflection condition is satisfied, the thickness of the light-transmitting medium can be made smaller. In addition, when the total reflection condition is met, the light coupled into the light-transmitting medium can be incident on the second beam combiner after being subjected to total reflection for one time or a plurality of times on the surfaces of the light-transmitting medium and air, so that the requirement of a thinner light-transmitting medium can be met. It will be appreciated by those skilled in the art that when one or more total reflections are used to reach the second beam combiner, the second beam combiner may be fabricated by taking the total reflection into account. All of which are intended to be within the scope of the present disclosure.

The second aspect of the present disclosure also relates to a volume holographic optical element manufactured by the above method 90, wherein the first volume holographic optical element and the second volume holographic optical element are each independently a transmissive volume holographic optical element or a reflective volume holographic optical element.

The second aspect of the present disclosure also relates to an optical assembly comprising a first beam combiner and a second beam combiner manufactured by the above-described method 90, the remainder being the same as the optical assembly of the first aspect of the present disclosure.

The structure of the optical component of the second aspect of the present disclosure is shown in fig. 1 to 7, for example, and therefore any feature or combination of features of the optical component of the first aspect of the present disclosure can be used in the optical component of the second aspect of the present disclosure, and will not be described herein again.

A second aspect of the present disclosure also relates to a display system comprising an optical assembly as described above. The display system is, for example, a virtual reality display system or an augmented reality display system.

According to a preferred embodiment of the present disclosure, the display system further comprises an image generation unit configured to generate an image to be displayed, the image generation unit being coupled to the light beam generator, light beams of different directions in a group of light beams emitted by the light beam generator carrying wavelength information and/or brightness information of different pixels in the image.

According to yet another aspect of the present disclosure, the present disclosure also relates to an optical assembly and a display system as described above and the use of an optical assembly and a display system manufactured by a method as described above in near-eye displays.

It should be noted that the embodiments of the present disclosure can be realized by hardware, software, or a combination of software and hardware. The hardware portion may be implemented using dedicated logic; the software portions may be stored in a memory and executed by a suitable instruction execution system, such as a microprocessor or specially designed hardware. Those skilled in the art will appreciate that the apparatus and methods described above may be implemented using computer executable instructions and/or embodied in processor control code, such code being provided on a carrier medium such as a disk, CD-or DVD-ROM, programmable memory such as read only memory (firmware), or a data carrier such as an optical or electronic signal carrier, for example. The apparatus and its modules of the present disclosure may be implemented by hardware circuits such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., or by software executed by various types of processors, or by a combination of the above hardware circuits and software, such as firmware.

It should be noted that although in the above detailed description several modules or sub-modules of the apparatus are mentioned, this division is only not mandatory. Indeed, the features and functions of two or more of the modules described above may be implemented in one module, according to embodiments of the present disclosure. Conversely, the features and functions of one module described above may be further embodied as divided into a plurality of modules.

While the present disclosure has been described with reference to presently contemplated embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments. On the contrary, the disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. Although the present disclosure has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes in the embodiments and modifications can be made, and equivalents can be substituted for elements thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. An optical assembly, comprising:

2. The optical assembly of claim 1, wherein the set of beams of the light cone distribution forms an illumination area on the first beam combiner that is proportional to an illumination area on the second beam combiner.

3. The optical assembly of claim 1, wherein the first and second beam combiners do not overlap in a direction perpendicular to an optical axis direction,

the main direction of the light beam group of the light cone distribution is perpendicular to the first light beam combiner and the second light beam combiner.

4. The optical assembly of claim 3, wherein marginal rays of the set of rays of the cone of rays pass through the first beam combiner in extension without passing through the second beam combiner.

5. The optical assembly of claim 1, wherein the first beam combiner is configured such that all beams exiting therefrom propagate through the optically transmissive medium onto the second beam combiner.

6. The optical assembly of claim 1, wherein the optical assembly has an entrance pupil and an exit pupil, the apex of the cone of light being the entrance pupil, the point at which light beams from a group of light beams of the same cone of light distribution converge after exiting the second beam combiner being the exit pupil.

7. The optical assembly of any one of claims 1-6, wherein the beam generator comprises an image source and a micro-electromechanical system,

wherein the laser beam is a monochromatic or three-color laser beam.

8. The optical assembly of any one of claims 1-6, wherein the beam generator comprises:

9. The optical assembly of any one of claims 1-6, wherein the beam generator comprises:

10. The optical assembly of claim 7, wherein the MEMS comprises a MEMS galvanometer, the image source generates an image by scanning beamlets from different wavelength lasers carrying color information and/or brightness information of image pixels, the image source comprises a plurality of different wavelength lasers, a controller coupled to the plurality of different wavelength lasers and controlling the plurality of different wavelength lasers to emit laser beams, and a combiner, the laser beams of the plurality of different wavelength lasers are incident on the combiner and combined into near-parallel beamlets whose spatial propagation paths are coincident.

11. The optical assembly of claim 10, wherein the beam combiner comprises a lens group and optical thin film beam splitters respectively corresponding to the wavelengths of the plurality of lasers with different wavelengths, wherein the lens group is configured to adjust the divergence angle and/or the diameter of the laser beam emitted by the laser, and project the laser beam onto the corresponding optical thin film beam splitters to form the near-parallel beamlets with the spatially coincident propagation paths through reflection or transmission, wherein the lens group may comprise a liquid lens or a liquid crystal lens, and the equivalent focal length of the lens group can be adjusted through external voltage control, so as to control the divergence angle and/or the diameter of the laser beam emitted by the laser.

12. The optical assembly of claim 11, wherein the beam combiner further comprises a stop, a wave plate, a polarizer, an attenuator plate disposed between the lens group and the optical film splitter plate, the beam combiner further comprising a micro-motor coupled to the lens group, the micro-motor being capable of adjusting a relative position between lenses in the lens group to adjust a divergence angle and/or a diameter of the light beam exiting the lens group.

13. The optical assembly according to any one of claims 1-6, wherein light beams of different directions in the set of light beams carry color information and/or brightness information of different image pixels.

14. The optical assembly according to any one of claims 1-6, wherein the first beam combiner comprises a first diffractive optical element, the light cone distribution of the set of light beams is diffracted when being incident on different positions of the first diffractive optical element, the diffracted light changes its propagation direction and continues to propagate in the light-transmitting medium, and is incident on different positions of the second beam combiner;

15. The optical assembly of claim 14, wherein the first and second diffractive optical elements are independently volume holographic optical elements, the first and second diffractive optical elements being one of the following combinations:

16. The optical assembly of claim 15, wherein the volume holographic optical element comprises a single color volume holographic optical element that diffracts laser light of different wavelengths of the plurality of lasers.

17. The optical assembly of claim 15, wherein the volume holographic optical element comprises a plurality of monochromatic volume holographic optical elements aligned and stacked together, corresponding to the number of the plurality of lasers, each sheet of monochromatic volume holographic optical element diffracting only laser light of the corresponding wavelength and not the other wavelengths.

18. The optical assembly of claim 15, wherein the volume holographic optical element comprises a plurality of volume holographic optical elements that are precisely aligned and stacked together, the plurality of volume holographic optical elements being fewer in number than the plurality of lasers, at least one of the plurality of volume holographic optical elements diffracting at least two wavelengths of laser light of the plurality of lasers and not diffracting other wavelengths of laser light; the remaining volume hologram optical elements diffract the remaining laser light of one of the other wavelengths, but do not diffract the remaining laser light of the other wavelengths.

19. The optical assembly of claim 15, wherein the volume holographic optical element comprises a single monochromatic volume holographic optical element that diffracts laser light of only one wavelength.

20. The optical assembly of any one of claims 16-19, wherein the first and second diffractive optical elements are independently one selected from the group consisting of the single color volume holographic optical element, the plurality of single color volume holographic optical elements that are precisely aligned and stacked together and correspond to the number of lasers, the plurality of single color volume holographic optical elements that are precisely aligned and stacked together and are fewer in number than the number of lasers, the single color volume holographic optical element.

21. A display system comprising the optical assembly of any one of claims 1-20.

22. The display system of claim 21, wherein the display system is a virtual reality display system or an augmented reality display system.

23. The display system according to claim 21 or 22, further comprising an image generation unit configured to generate an image to be displayed, the image generation unit being coupled to the light beam generator, the light beams of different directions of the set of light beams emitted by the light beam generator carrying color information and/or brightness information of different pixels in the image.

24. A display system according to claim 21 or 22, comprising a left eye display unit and a right eye display unit, wherein the left eye display unit and the right eye display unit each comprise an optical assembly according to any one of claims 1-20.

25. Use of an optical assembly according to any one of claims 1-20 or a display system according to any one of claims 21-24 for near-eye display.

26. An image projection method of an optical system, comprising:

step S81: generating a light beam group with light cone distribution;

wherein the first surface is parallel to the second surface.

27. An image projection method according to claim 26, wherein the illumination area formed on the first beam combiner by the beam group of the light cone distribution is in equal proportion to the illumination area formed on the second beam combiner.

28. The image projection method of claim 26, wherein the optical system has an entrance pupil whose vertex is the exit pupil, and the point at which light beams from a group of light beams of the same light cone distribution converge after exiting the second beam combiner is the exit pupil.

29. The image projection method according to any of claims 26-28, wherein the beam generator comprises a laser light source and a micro-electro-mechanical system,

wherein the step S81 includes:

30. The image projection method according to any of claims 26-28, wherein said step S81 comprises:

31. The image projection method according to any of claims 26-28, wherein said step S81 comprises:

32. The image projection method according to any of claims 26 to 28, wherein the image projection method is implemented using an optical assembly according to any of claims 1 to 20 or a display system according to any of claims 21 to 24.