Refraction-reflection hybrid near-to-eye display optical structure

Abstract

The invention discloses a catadioptric hybrid near-to-eye display optical structure. The catadioptric hybrid near-to-eye display optical structure is composed of a micro display screen module and a catadioptric diffraction light path module. The micro display screen module comprises a plurality of micron / nano-scale display chips and a micro-collimation structure and is embedded into the lens, and the light-emitting surface of the micro display screen module is back to human eyes, so that external observation is not influenced; the refraction-reflection-diffraction light path module comprises at least one transmission type diffraction element and one reflection type diffraction element, two times of refraction and reflection of light are achieved through the micro-nano optical structure design, and the field angle (FOV) can be enlarged or multiple viewpoints can be formed to expand the eye box. The structure slows down convergence focusing conflicts (VAC) through retina-like projection, ambient light efficiently penetrates through the middle parts of the lenses to realize an augmented reality (AR) function, and meanwhile, the structure has the characteristics of high integration level and light weight, and is suitable for near-to-eye display equipment such as intelligent glasses and helmets.

Description

Technical Field

[0001] This invention belongs to the fields of display technology and micro / nano structures, and specifically relates to an eye-tracking transparent near-eye display optical structure based on deflectable pixel light rays. Background Technology

[0002] Near-eye display, also known as head-mounted display or wearable display, creates virtual images within the field of view of one or both eyes. It uses a display device placed at a distance from the human eye's direct vision to render light field information, thereby reconstructing a virtual scene in front of the eyes. Near-eye displays include augmented reality (AR), virtual reality (VR), and mixed reality (MR). Virtual reality (VR) technology allows users to immerse themselves in virtual objects; augmented reality (AR) technology allows users to see virtual objects superimposed with information from the real world, greatly expanding the user's perceptual interface; near-eye display technology products are developing towards being lighter, thinner, and more portable, while the content rendered by near-eye displays is also required to be more comfortable, more realistic, and smoother.

[0003] Traditional near-eye display structures suffer from convergence-focus conflict (VAC), which can easily cause eye strain during prolonged viewing. They are also small in size, have small eye boxes, and large system volume, which affects the user experience.

[0004] Pico projection: A miniaturized projection technology that projects images or videos onto a screen or other surface using a high-brightness LED or laser light source. Pico projection devices are typically small, portable, and flexible, suitable for various environments and applications.

[0005] Traditional micro-projectors mainly rely on LEDs or lasers as light sources and use technologies such as DLP, LCoS, and LBS to achieve projection display. Since the light source and image source are generated by different devices, the structure has significant limitations. Summary of the Invention

[0006] To address the aforementioned technical problems in existing technologies, this invention proposes a catadioptric hybrid near-eye display optical structure. This structure utilizes a catadioptric diffraction optical path module to control light. After reflection and transmission within the system, the light can expand the field of view (FOV). Alternatively, through careful design of the transmission diffraction elements, multiple viewpoints can be formed on the plane of the human eye's pupil, creating a larger eyebox. The human eye can observe images at different viewpoints by rotating its head. Subsequently, the light directly synthesizes the image on the retina, mitigating convergence-focusing conflict (VAC) and creating a retinal-like projection effect.

[0007] To achieve the above objectives, the present invention provides a catadioptric hybrid near-eye display optical structure, comprising:

[0008] The microdisplay module comprises at least one microdisplay chip and a microcollimation structure array. The microdisplay chip is a micrometer-level pixel chip or a nanometer-level pixel chip, and the microcollimation structure is an array composed of microlenses, TIR lenses, metasurfaces, or photonic crystals. The microdisplay module is distributed around the frame or in part of the lens. The light-emitting surface of the microdisplay module faces away from the human eye and does not affect external observation. Chips in different areas can display the same or different images to achieve multi-viewpoint or brightness superposition functions.

[0009] The catadioptric diffraction optical path module consists of at least two diffractive optical elements, including a transmissive diffraction element close to the human eye and a reflective diffraction element far from the human eye. The elements include subwavelength gratings, photonic crystals, or metasurfaces, and are made of dielectric or metallic materials. The substrate of the transmissive diffraction element has a spherical, cylindrical, conical, or freeform surface curvature. Achromatic aberration, spherical aberration elimination, and field of view expansion are achieved by jointly controlling the substrate curvature and the diffraction structure.

[0010] The microdisplay chip is located between the transmissive and reflective diffraction elements and emits light away from the human eye. The light emitted from the microdisplay chip in the reflected light path is reflected by the reflective diffraction element and then converged by the transmissive diffraction element before entering the eye. Furthermore, the minimum unit period of the diffraction element satisfies the Schneider sampling theorem. The phase change ranges from 0 to 2π, the transmittance of transmissive elements is ≥50%, and the reflectivity of reflective elements is ≥30%.

[0011] In one specific embodiment, the catadioptric optical path module can perform temporal or spatial multiplexing of polarized light. Circularly polarized light is separated into left-handed and right-handed circularly polarized light after passing through the module, forming multi-viewpoint or 3D display functions.

[0012] In one specific embodiment, the feature is:

[0013] The light emitted by the microdisplay chip passes through a reflective diffraction element and then through a gap region where the microdisplay chip is deployed on the lens. When the microdisplay chip is deployed in the peripheral area of ​​the lens, the light emitted by the microdisplay chip is reflected and passes through the center to reach the surface of the transmissive diffraction element. When the microdisplay chip is deployed in the central area of ​​the lens, the light passes through all four sides to reach the surface of the transmissive diffraction element.

[0014] Alternatively, a light-absorbing device may be provided between the micro-display module and the catadioptric optical path module, wherein the type of the light-absorbing device includes a black matrix module.

[0015] In one specific embodiment, AR / VR mode switching is achieved by adjusting the reflectivity / transmittance of the diffraction element: the diffraction element filled with liquid crystal material controls the transmittance of ambient light through an electric field, with high transmittance indicating AR mode and low transmittance indicating VR mode; or the AR function is achieved by arranging the diffraction element around the lens, with the central area allowing ambient light to pass through.

[0016] In one specific embodiment, micro-nano structures are fabricated using femtosecond laser direct writing, electron beam etching, focused ion beam etching, nanoimprinting, or interference lithography. The integration of micro-displays and metasurfaces is achieved through layer transfer or two-photon polymerization 3D printing. Glass or highly transparent polymers are used as substrate materials, and the processing precision reaches the submicron level.

[0017] In one specific embodiment, the microdisplay chip includes: a micrometer-level pixel chip of Micro-LED, Micro-QLED, Micro-OLED, or Micro-PeLED, or a nanometer-level pixel chip of Nano-LED, Nano-QLED, Nano-OLED, or Nano-PeLED.

[0018] In one specific embodiment, the catadioptric diffraction optical element can achieve optical field modulation by changing the equivalent refractive index and thus altering the phase of the light rays, or it can achieve modulation by changing the polarization state or amplitude of the light rays. The minimum unit period of the catadioptric diffraction optical element needs to satisfy the Schneider sampling law, that is:

[0019]

[0020] Where U is the minimum period, λ is the operating wavelength, and NA is the numerical aperture;

[0021] Simultaneously, this structure needs to satisfy a phase change of 0-2π; when the diffraction element is transmissive, it needs to satisfy a light transmittance of over 50%; when the diffraction element is reflective, it needs to satisfy a light reflectance of over 30%; the phase accumulated during transmission must satisfy:

[0022]

[0023] Wherein, the equivalent refractive index of the medium is n, the working wavelength is λ, and the distance the electromagnetic wave travels in the medium is d.

[0024] In one specific embodiment, a transmission diffraction element can be used to focus a microdisplay image onto the center of the human eye's pupil or retina, and the phase formula for focusing includes, but is not limited to:

[0025] Spherical lens:

[0026] Cylindrical lens:

[0027] Conical lens:

[0028] Where x and y represent the coordinates. This represents the compensated phase, λ is the operating wavelength, and NA is the numerical aperture.

[0029] This transmission diffraction element can also be used to achieve achromatic functions, as shown in the following formula:

[0030]

[0031] In one specific embodiment, the light beam deflection effect is achieved by passing through both reflective and transmissive diffraction elements, which can be determined by, but is not limited to, the generalized Snell's law, as shown in the following formula:

[0032] Transmission type:

[0033] Reflective:

[0034] Where n represents the refractive index, n t n represents the refractive index of the medium at the transmission surface. r n represents the refractive index of the medium on the reflecting surface. i θ represents the refractive index of the medium at the incident surface. t θ represents the angle between the normal and the transmitted ray. r θ represents the angle between the normal and the reflected ray. i This represents the angle between the normal and the incident light. It is the phase gradient.

[0035] In one specific embodiment, the catadioptric diffraction optical path module is replaced by a dual reflection optical path module. The dual reflection optical path module consists of at least two diffractive optical elements. The microdisplay chip emits light towards the human eye, which is reflected by the first reflective diffraction optical path module close to the human eye. The light then falls onto the second reflective focusing diffraction optical path module far from the human eye and is then reflected and focused onto the human eye.

[0036] Compared with existing technologies, this invention has the following significant advantages: 1) By using a catadioptric diffraction optical path module to control light, the light can expand the field of view (FOV) after reflection and transmission in the system. Alternatively, through careful design of the transmission diffraction element, multiple viewpoints can be formed on the plane of the human eye's pupil, forming a larger eyebox. The human eye can observe images at different viewpoints by rotating its head. Subsequently, the light directly synthesizes the image on the retina, reducing convergence-focusing conflict (VAC) and forming a retinal-like projection effect; 2) By using the phase design of the diffraction element, chromatic aberration and spherical aberration are eliminated, improving image quality; 3) At the same time, by deploying the catadioptric diffraction optical path module around the lens, ambient light can pass through the center of the lens efficiently and without distortion, achieving augmented reality (AR) functionality in conjunction with the display module; This system has high integration, is lightweight, and small in size, and conforms to the development trend of lightweight wearable electronic devices. It can be applied to near-eye display devices such as smart helmets and smart glasses. Attached Figure Description

[0037] Figure 1 This is a global view of Embodiment 1 of the present invention.

[0038] Figure 2 This is a schematic diagram of the augmented reality (AR) structure of Embodiment 1 of the present invention.

[0039] Figure 3 This is a schematic diagram of the virtual reality (VR) structure of Embodiment 2 of the present invention.

[0040] Figure 4 This is a schematic diagram of partial light rays in Embodiment 2 of the present invention.

[0041] Figure 5 This is a schematic diagram of the augmented reality (AR) multi-view structure of Embodiment 3 of the present invention.

[0042] Figure 6 This is a schematic diagram of the achromatic structure for virtual reality (VR) in Embodiment 4 of the present invention.

[0043] Explanation of the reference numerals in the attached figures:

[0044] 101: Reflection diffraction element, 102: Transmission diffraction element, 103: Microdisplay chip, 104: Light emitted by microdisplay chip, 105: Light reflected by diffraction element, 106: External natural light, 107: Human eye structure, 108: Independent sub-image, 109: Eyeglass frame;

[0045] 201: Reflective diffraction element; 202: Focusing transmission diffraction element; 203: Microdisplay chip; 204: Light emitted by the microdisplay chip; 205: Diffraction element reflects and focuses light; 207: Human eye structure; 2041: Green light emitted by the microdisplay chip; 2042: Red light emitted by the microdisplay chip; 2043: Blue light emitted by the microdisplay chip; 2051: Green light deflected by the diffraction element; 2052: Red light deflected by the diffraction element; 2053: Blue light deflected by the diffraction element. Detailed Implementation

[0046] The embodiments of this patent are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this patent, and should not be construed as limiting this patent.

[0047] Example 1

[0048] In a first embodiment of the present invention, a catadioptric hybrid near-eye display optical structure is provided, comprising:

[0049] The microdisplay module comprises at least one microdisplay chip and a microcollimation structure array. The microdisplay chip is a micrometer-level pixel chip or a nanometer-level pixel chip, and the microcollimation structure is an array composed of microlenses, TIR lenses, metasurfaces, or photonic crystals. The microdisplay module is distributed around the frame or in part of the lens. The light-emitting surface of the microdisplay module faces away from the human eye and does not affect external observation. Chips in different areas can display the same or different images to achieve multi-viewpoint or brightness superposition functions.

[0050] The catadioptric diffraction optical path module consists of at least two diffractive optical elements, including a transmissive diffraction element close to the human eye and a reflective diffraction element far from the human eye. The elements include subwavelength gratings, photonic crystals, or metasurfaces, and are made of dielectric or metallic materials. The substrate of the transmissive diffraction element has a spherical, cylindrical, conical, or freeform surface curvature. Achromatic aberration, spherical aberration elimination, and field of view expansion are achieved by jointly controlling the substrate curvature and the diffraction structure.

[0051] The microdisplay chip is located between the transmissive and reflective diffraction elements and emits light away from the human eye. The light emitted from the microdisplay chip in the reflected light path is reflected by the reflective diffraction element and then converged by the transmissive diffraction element before entering the eye. Furthermore, the minimum unit period of the diffraction element satisfies the Schneider sampling theorem. The phase change ranges from 0 to 2π, the transmittance of transmissive elements is ≥50%, and the reflectivity of reflective elements is ≥30%.

[0052] In this embodiment, the catadioptric optical path module can perform temporal or spatial multiplexing of polarized light. Circularly polarized light is separated into left-handed and right-handed circularly polarized light after passing through the module, forming multi-viewpoint or 3D display functions.

[0053] It is worth mentioning that the light emitted by the microdisplay chip returns after passing through the reflective diffraction element and can pass directly through the gaps in the microdisplay chip deployment, but this will generate some crosstalk. Therefore, the light emitted by the microdisplay chip passes through the reflective diffraction element and then through the gap area where the microdisplay chip is deployed on the lens. Specifically, when the microdisplay chip is deployed in the peripheral area of ​​the lens, the reflected light can pass through the center to the surface of the transmissive diffraction element; when the microdisplay chip is deployed in the central area of ​​the lens, the light passes through the surrounding area to the surface of the transmissive diffraction element. Based on this, by spatially staggering the light rays, the crosstalk will be greatly reduced, as shown in the attached figure. Figure 2 As shown; in addition, an appropriate light-absorbing device, including but not limited to a black matrix module, can be set between the display module and the catadioptric optical path module to absorb stray light and reduce crosstalk between light rays.

[0054] Therefore, the following two methods can be used to reduce crosstalk between light rays:

[0055] 1) The light emitted by the microdisplay chip passes through the reflective diffraction element and then through the gap area where the microdisplay chip is deployed on the lens; wherein, when the microdisplay chip is deployed in the surrounding area of ​​the lens, the light emitted by the microdisplay chip can pass through the middle after reflection and arrive at the surface of the transmissive diffraction element; when the microdisplay chip is deployed in the central area of ​​the lens, the light passes through from all sides and arrives at the surface of the transmissive diffraction element;

[0056] 2) Or a light-absorbing device disposed between the micro-display module and the catadioptric optical path module, wherein the type of the light-absorbing device includes a black matrix module.

[0057] In this embodiment, AR / VR mode switching is achieved by adjusting the reflectivity / transmittance of the diffraction element: the diffraction element filled with liquid crystal material controls the transmittance of ambient light through an electric field, with high transmittance indicating AR mode and low transmittance indicating VR mode; or the AR function is achieved by arranging the diffraction element around the lens, with the central area allowing ambient light to pass through.

[0058] Typically, by filling the structure with materials such as liquid crystals, the reflectivity and transmittance of the diffraction elements used in the structure can be adjusted. The transmittance of ambient light through reflective diffraction elements located away from the human eye can be controlled by an electric field. When the ambient light transmittance is high, augmented reality (AR) is achieved; when the ambient light transmittance is low, virtual reality (VR) functionality is achieved.

[0059] In addition, the reflectivity and transmittance of the diffraction elements used in the structure can be fixed, and the reflective and transmissive diffraction elements can be arranged around the lens in a spatial manner, leaving the central area for ambient light to pass through, so as to achieve the augmented reality effect.

[0060] Optionally, in practical applications, micro- and nanostructures are fabricated using femtosecond laser direct writing, electron beam etching, focused ion beam etching, nanoimprinting, or interference lithography. The integration of micro-displays and metasurfaces is achieved through layer transfer or two-photon polymerization 3D printing, using glass or highly transparent polymers as substrate materials, with processing precision reaching the submicron level.

[0061] The fabrication methods for the entire spectacle lens structure include, but are not limited to, micro / nano fabrication techniques such as femtosecond laser direct writing, electron beam etching, focused ion beam etching, nanoimprinting, and interference lithography. A microdisplay and a fabricated metasurface are integrated, achieving a tight bond between them through layer transfer technology or two-photon polymerization 3D printing. Then, an optically transparent material is used to encapsulate the structure within a transparent spectacle lens, ensuring structural stability and optical performance. The transparent substrate material of the spectacle lens is glass or a highly transparent polymer. The fabrication precision of the microdisplay and metasurface is sub-micron level to ensure optical performance. The metasurface is designed to achieve diffraction, focusing, or polarization control of light to optimize display effects.

[0062] In addition, optionally, the microdisplay chip includes: a micron-level pixel chip of Micro-LED, Micro-QLED, Micro-OLED, or Micro-PeLED, or a nano-level pixel chip of Nano-LED, Nano-QLED, Nano-OLED, or Nano-PeLED.

[0063] In this embodiment, the catadioptric diffraction optical element can achieve optical field modulation by changing the equivalent refractive index and thus altering the phase of the light rays, or it can achieve modulation by changing the polarization state or amplitude of the light rays. The minimum unit period of the catadioptric diffraction optical element needs to satisfy the Schneider sampling law, that is:

[0064]

[0065] Where U is the minimum period, λ is the operating wavelength, and NA is the numerical aperture;

[0066] Simultaneously, this structure needs to satisfy a phase change of 0-2π; when the diffraction element is transmissive, it needs to satisfy a light transmittance of over 50%; when the diffraction element is reflective, it needs to satisfy a light reflectance of over 30%; the phase accumulated during transmission must satisfy:

[0067]

[0068] Wherein, the equivalent refractive index of the medium is n, the working wavelength is λ, and the distance the electromagnetic wave travels in the medium is d.

[0069] It is worth mentioning that the aforementioned micro-nano optical elements can also be used to control the light field by adjusting the amplitude, phase, polarization state, etc. When the micro-nano optical element is a photonic crystal, the photonic crystal can be one-dimensional, two-dimensional, or three-dimensional. When the micro-nano optical element is a metasurface, the amplitude, phase, polarization, and other physical quantities of the light field can be freely controlled by designing the material, geometry, characteristic size, period, etc. of the antenna on the metasurface. The phase modulation methods include, but are not limited to, propagation phase, geometric phase, topological phase, and combinations of multiple phase modulations. When the micro-nano optical element is a subwavelength grating, the methods for adjusting the equivalent refractive index include, but are not limited to, changing the duty cycle and geometry in the subwavelength grating structure.

[0070] Furthermore, transmission diffraction elements can be used to focus images from microdisplays onto the center of the human eye's pupil or retina, and the phase formula for focusing includes, but is not limited to:

[0071] Spherical lens:

[0072] Cylindrical lens:

[0073] Conical lens:

[0074] Where x and y represent the coordinates. This represents the compensated phase, λ is the operating wavelength, and NA is the numerical aperture.

[0075] This transmission diffraction element can also be used to achieve achromatic functions, as shown in the following formula:

[0076]

[0077] Furthermore, the beam deflection effect achieved by light passing through reflective and transmissive diffraction elements can be determined by, but is not limited to, the generalized Snell's law, as shown in the following formula:

[0078] Transmission type:

[0079] Reflective:

[0080] Where n represents the refractive index, n t n represents the refractive index of the medium at the transmission surface. r n represents the refractive index of the medium on the reflecting surface. i θ represents the refractive index of the medium at the incident surface.t θ represents the angle between the normal and the transmitted ray. r θ represents the angle between the normal and the reflected ray. i This represents the angle between the normal and the incident light. It is the phase gradient.

[0081] In typical scenarios, by applying the generalized Snell's law, the deflection angle of light is increased through two refractions, thus expanding the field of view. The angle at which the light is deflected by the refraction-diffraction optical path module can be any angle that conforms to the generalized Snell's law. Alternatively, specific diffraction structures can be designed for different wavelengths in different regions. These different wavelengths of light have different deflection angles after passing through specific regions, and are finally focused by the human eye, achieving the function of achromatic aberration. Alternatively, the achromatic aberration function can be achieved by designing multi-layer diffraction structures, Fresnel ring structures, etc.

[0082] Example 2

[0083] The second embodiment of the present invention is basically the same as the first embodiment, except that the reflective diffraction optical path module is replaced by a dual reflection optical path module. The dual reflection optical path module is composed of at least two diffractive optical elements. The microdisplay chip emits light to the human eye, which is reflected by the first reflective diffraction optical path module close to the human eye. The light then falls on the second reflective focusing diffraction optical path module far from the human eye and is then reflected and focused onto the human eye.

[0084] Example 3

[0085] The third embodiment of the present invention is based on the first embodiment and is further illustrated with specific application scenarios.

[0086] like Figure 1 As shown, when the structure is used to realize AR function, the micro display module is composed of multiple 103 micro display chips; the catadioptric diffraction optical path module is composed of a reflection diffraction element 101 and a transmission diffraction element 102. The micro display chip 103 emits light 104, which is reflected by the reflection diffraction element 101 and transmitted by the transmission diffraction element 102 to form a catadioptric light 105 that converges to the human eye 107.

[0087] The optical structure described herein operates as follows: the light emitted from the reflective diffractor 101 is directed toward the edge of the lens, and then the light is collected by the transmission diffractors deployed around the lens and focused onto the human eye, leaving the middle part for the ambient light 106 to pass through.

[0088] like Figure 3As shown, when the structure is used to implement VR function, the micro display module is composed of multiple 203 micro display chips; the catadioptric diffraction optical path module is composed of a reflection diffraction element 201 and a transmission diffraction element 202. The micro display chip 203 emits light 204, which is reflected by the reflection diffraction element 201 and transmitted by the transmission diffraction element 202, forming a catadioptric light 205 that converges at multiple focal points to the human eye 107.

[0089] The optical structure described herein operates as follows: the light emitted from the reflective diffractor 201 is directed toward the center of the lens, and then the light is collected by the transmission focusing diffractor 202 deployed on the rear lens and focused onto the human eye. The transmission focusing element 202 can be designed in sections to form multiple viewpoints in front of the human eye.

[0090] like Figure 5 As shown, when the structure is used to realize AR function and to realize multiple viewpoints, the micro display module is composed of multiple 103 micro display chips; the catadioptric diffraction optical path module is composed of a reflection diffraction element 101 and a transmission diffraction element 102. The micro display chip 103 emits light 104. At this time, each display module 103 displays an independent image 108. The catadioptric light 105 formed after reflection by the reflection diffraction element 101 and transmission by the transmission diffraction element 102 presents multiple independent sub-image sources 108 in front of the human eye.

[0091] The specific working state of the optical structure described herein is as follows: the light emitted after passing through the reflection diffraction element 101 is directed towards the edge of the lens, and then the light is collected and deflected to various angles in front of the eyes by the transmission diffraction elements deployed around the lens. This can be either one-dimensional pupil expansion or two-dimensional pupil expansion, leaving the middle part for ambient light 106 to pass through.

[0092] like Figure 6 As shown, when the structure is designed to achieve VR functionality and color difference ablation, the microdisplay module is composed of multiple 203 microdisplay chips. At this time, the microdisplay modules 203 at different positions emit green light 2041, red light 2042, and blue light 2043. The reflective diffraction optical path module is composed of a reflective diffraction element 201 and a transmission diffraction element 202. The microdisplay chip 203 emits RGB light, which, after being reflected by the reflective diffraction element 201 and transmitted by the transmission diffraction element 202, forms green light 2051, red light 2052, and blue light 2053, which then converge at the human eye 207.

[0093] The optical structure described herein operates as follows: the light emitted from the reflective diffractor 201 is directed toward the center of the lens, and then the light is collected by the transmission diffractor 202 deployed on the rear lens and then deflected and focused onto the human eye. The transmission focusing element 202 can be designed in sections, and specific high-efficiency diffraction structures can be designed according to different wavelengths, so that the RGB three-color light converges at the same position, achieving regional achromatic aberration.

[0094] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A hybrid catadioptric near-eye display optical structure, characterized in that, include: The microdisplay module comprises at least one microdisplay chip and a microcollimation structure array. The microdisplay chip is a micrometer-level pixel chip or a nanometer-level pixel chip, and the microcollimation structure is an array composed of microlenses, TIR lenses, metasurfaces, or photonic crystals. The microdisplay module is distributed around the frame or in part of the lens. The light-emitting surface of the microdisplay module faces away from the human eye and does not affect external observation. Chips in different areas can display the same or different images to achieve multi-viewpoint or brightness superposition functions. The catadioptric diffraction optical path module consists of at least two diffractive optical elements, including a transmissive diffraction element close to the human eye and a reflective diffraction element far from the human eye. The elements include subwavelength gratings, photonic crystals, or metasurfaces, and are made of dielectric or metallic materials. The substrate of the transmissive diffraction element has a spherical, cylindrical, conical, or freeform surface curvature. Achromatic aberration, spherical aberration elimination, and field of view expansion are achieved by jointly controlling the substrate curvature and the diffraction structure. The microdisplay chip is located between the transmissive and reflective diffraction elements and emits light away from the human eye. The light emitted from the microdisplay chip in the reflected light path is reflected by the reflective diffraction element and then converged by the transmissive diffraction element before entering the eye. Furthermore, the minimum unit period of the diffraction element satisfies the Schneider sampling theorem. The phase change ranges from 0 to 2π, the transmittance of transmissive elements is ≥50%, and the reflectivity of reflective elements is ≥30%.

2. The structure according to claim 1, characterized in that, The catadioptric diffraction optical path module can perform time or space multiplexing of polarized light. Circularly polarized light is separated into left-handed and right-handed circularly polarized light after passing through the module, forming multi-viewpoint or 3D display functions.

3. The structure according to claim 1, characterized in that: The light emitted by the microdisplay chip passes through a reflective diffraction element and then through a gap region where the microdisplay chip is deployed on the lens. When the microdisplay chip is deployed in the peripheral area of ​​the lens, the light emitted by the microdisplay chip is reflected and passes through the center to reach the surface of the transmissive diffraction element. When the microdisplay chip is deployed in the central area of ​​the lens, the light passes through all four sides to reach the surface of the transmissive diffraction element. Alternatively, a light-absorbing device may be provided between the micro-display module and the catadioptric optical path module, wherein the type of the light-absorbing device includes a black matrix module.

4. The structure according to claim 1, characterized in that, AR / VR mode switching is achieved by adjusting the reflectivity / transmittance of diffractive elements: the diffractive elements filled with liquid crystal material control the transmittance of ambient light through an electric field, with high transmittance indicating AR mode and low transmittance indicating VR mode; or by arranging diffractive elements around the lens, allowing ambient light to pass through the central area to achieve AR function.

5. The structure according to claim 1, characterized in that, Micro- and nanostructures are fabricated using femtosecond laser direct writing, electron beam etching, focused ion beam etching, nanoimprinting, or interference lithography. The integration of micro-displays and metasurfaces is achieved through layer transfer or two-photon polymerization 3D printing. Glass or highly transparent polymers are used as substrate materials, and the processing precision reaches the sub-micron level.

6. The structure according to claim 1, characterized in that, The microdisplay chip includes: micron-level pixel chips of Micro-LED, Micro-QLED, Micro-OLED, and Micro-PeLED, or nanon-level pixel chips of Nano-LED, Nano-QLED, Nano-OLED, and Nano-PeLED.

7. The near-eye display optical structure according to claims 1 and 4, characterized in that, The catadioptric diffractive optical element can achieve optical field manipulation by changing the equivalent refractive index and thus altering the phase of the light rays, or by changing the polarization state or amplitude of the light rays. The minimum unit period of the catadioptric diffractive optical element must satisfy the Schneider sampling law, i.e.: Where U is the minimum period, λ is the operating wavelength, and NA is the numerical aperture; Simultaneously, this structure needs to satisfy a phase change of 0-2π; when the diffraction element is transmissive, it needs to satisfy a light transmittance of over 50%; when the diffraction element is reflective, it needs to satisfy a light reflectance of over 30%; the phase accumulated during transmission must satisfy: Wherein, the equivalent refractive index of the medium is n, the working wavelength is λ, and the distance the electromagnetic wave travels in the medium is d.

8. The near-eye display optical structure with a catadioptric hybrid design according to claim 1, characterized in that, Transmission diffraction elements can be used to focus images from microdisplays onto the center of the human eye's pupil or retina, and the phase formula for focusing includes, but is not limited to: Spherical lens: Cylindrical lens: Conical lens: Where x and y represent the coordinates. This represents the compensated phase, λ is the operating wavelength, and NA is the numerical aperture. This transmission diffraction element can also be used to achieve achromatic functions, as shown in the following formula:

9. The near-eye display optical structure of the catadioptric hybrid type according to claim 1, characterized in that, The deflection of light beams by reflecting and transmitting diffraction elements can be determined using, but is not limited to, the generalized Snell's law, as shown in the following formula: Transmission type: Reflective: Where n represents the refractive index, n t n represents the refractive index of the medium at the transmission surface. r n represents the refractive index of the medium on the reflecting surface. i θ represents the refractive index of the medium at the incident surface. t θ represents the angle between the normal and the transmitted ray. r θ represents the angle between the normal and the reflected ray. i This represents the angle between the normal and the incident light. It is the phase gradient.

10. The near-eye display optical structure of the catadioptric hybrid type according to claim 1, characterized in that, The catadioptric diffraction optical path module is replaced by a dual reflection optical path module. The dual reflection optical path module consists of at least two diffractive optical elements. The microdisplay chip emits light towards the human eye, which is reflected by the first reflection diffraction optical path module close to the human eye. The light then falls on the second reflection focusing diffraction optical path module far from the human eye and is then reflected and focused onto the human eye.

Images