Display optical system and display device

Abstract

The utility model discloses a display optical system and a display device, relates to the technical field of display, and can improve the display definition. The display optical system comprises: a light source for emitting display light; the first grating is arranged on the light-emitting side of the light source; the optical waveguide structure is arranged on the side, away from the light source, of the first grating, the side, close to the first grating, of the optical waveguide structure comprises a light-in area and a light-out area, the light-in area and the light-out area are not overlapped, and the orthographic projection of the first grating on the optical waveguide structure covers the light-in area; the second grating and the first grating are arranged on the same side of the optical waveguide structure; the orthographic projection of the second grating on the optical waveguide structure covers a light emitting area; the second grating is located between the first optical lens and the optical waveguide structure, the orthographic projection of the second grating on the optical waveguide structure falls into the orthographic projection of the first optical lens on the optical waveguide structure, the first optical lens comprises a first nano-structure layer and a first substrate, and the first nano-structure layer is arranged on the side, away from the second grating, of the first substrate.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a display optical system and display device. Background Technology

[0002] Augmented Reality (AR) technology is a technique that cleverly integrates virtual information with the real world. It simulates computer-generated text, images, 3D models, music, videos, and other virtual information and applies them to the real world. The two types of information complement each other, thus "enhancing" the real world. However, existing AR display technologies, in order to improve the quality of the image, need to display the virtual image at infinity. This makes it unclear to the human eye and easily causes visual fatigue. Summary of the Invention

[0003] This application provides a display optical system and display device that can improve display clarity.

[0004] A first aspect of this application provides a display optical system, comprising:

[0005] A light source, used to emit display light;

[0006] A first grating is disposed on the light-emitting side of the light source;

[0007] An optical waveguide structure is disposed on the side of the first grating away from the light source. The side of the optical waveguide structure close to the first grating includes an incident light region and an exit light region. The incident light region and the exit light region do not overlap. The orthographic projection of the first grating onto the optical waveguide structure covers the incident light region.

[0008] The second grating and the first grating are disposed on the same side of the optical waveguide structure. The orthographic projection of the second grating on the optical waveguide structure covers the light-emitting area. The first grating and the second grating are spaced apart by a preset distance.

[0009] A first optical lens, and a second grating located between the first optical lens and the optical waveguide structure, wherein the orthographic projection of the second grating on the optical waveguide structure falls within the orthographic projection of the first optical lens on the optical waveguide structure;

[0010] The first optical lens includes a first nanostructure layer and a first substrate, wherein the first nanostructure layer is disposed on the side of the first substrate away from the second grating.

[0011] In some embodiments, the first optical lens includes a plurality of the nanounit structures and a plurality of the first substrates;

[0012] The nanounit structure is configured one-to-one with the first substrate; or...

[0013] The first optical lens includes a plurality of the nanounit structures and a first substrate;

[0014] A plurality of the nanounit structures are disposed on the first substrate.

[0015] In some embodiments, the first nanostructure layer includes a plurality of nanocylinders with different radii, the different radii of which correspond to different phases and different amplitudes of the light field emitted from the optical waveguide structure.

[0016] In some embodiments, the first nanostructure layer comprises an array of multiple nanocubes and / or nanocubes arranged in an array.

[0017] In some embodiments, the size of the first optical lens in a first direction is greater than or equal to the size of the second grating in the first direction, wherein the first direction is the direction from the incident light region to the exit light region.

[0018] In some embodiments, the display optical system is characterized by further comprising:

[0019] The second optical lens is located on the side of the optical waveguide structure opposite to the first optical lens, and the orthographic projection of the second optical lens on the optical waveguide structure overlaps with the orthographic projection of the first optical lens on the optical waveguide structure.

[0020] In some embodiments, the display optical system is characterized by further comprising:

[0021] A collimating lens group is located between the light source and the first grating, wherein the collimating lens group includes at least one collimating lens;

[0022] The third optical lens is located between the collimating lens group and the light source, and the orthographic projection of the first grating on the optical waveguide structure falls within the orthographic projection of the third optical lens on the optical waveguide structure;

[0023] And / or,

[0024] The third optical lens includes the nanocylinder; and / or,

[0025] The second optical lens comprises a nanocylinder.

[0026] In some embodiments, the third optical lens has a smaller dimension in a first direction than the first optical lens in the first direction, where the first direction is the direction from the incident light region to the exit light region;

[0027] The orthographic projection of the third optical lens onto the optical waveguide structure does not overlap with the orthographic projection of the first optical lens onto the optical waveguide structure.

[0028] In some embodiments, the radius of the nanocylinders ranges from 40 nm to 140 nm; and / or,

[0029] The height of the nanocylinders ranges from 400 nm to 900 nm.

[0030] In some embodiments, the display optical system is characterized by,

[0031] The first grating includes a surface-embossed diffraction grating or a volume holographic diffraction grating; and / or,

[0032] The second grating includes a surface relief diffraction grating or a volume holographic diffraction grating;

[0033] And / or,

[0034] The tilt angle of the surface-embossed diffraction grating ranges from 30° to 45°; and / or,

[0035] The height range of the surface relief diffraction grating is 300 nm to 500 nm.

[0036] In some embodiments, the first grating comprises an array of micro / nano structures; and / or,

[0037] The second grating includes a micro / nano structure array, wherein the dimensions of the first grating in the second direction are the same as the dimensions of the second grating in the second direction, wherein the second direction is perpendicular to the first direction.

[0038] In some embodiments, the projected area of ​​the second grating on the optical waveguide structure is larger than the projected area of ​​the first grating on the optical waveguide structure; and / or,

[0039] The preset distance between the first grating and the second grating is in the range of 20mm to 30mm.

[0040] A second aspect of this application provides a display device, comprising:

[0041] The display optical system is as described in the first aspect.

[0042] The display optical system provided in this application embodiment features a first grating on one side of the light-incident area of ​​an optical waveguide structure, a second grating on the light-exit area, a light source positioned corresponding to the light-incident area, and the human eye located in the light-exit area. The first grating couples the display light emitted from the light source into the optical waveguide structure, where it undergoes total internal reflection and exits from the light-exit area. The second grating couples the total internal reflection-reflected display light out of the optical waveguide structure. By placing a first optical lens in the light-exit area of ​​the optical waveguide structure facing the human eye, and by employing multiple subwavelength micro-nano structures, the optical system can be integrated into a thinner and lighter form factor, resulting in a smaller overall product size. Simultaneously, it modulates the amplitude, phase, and polarization of the display light emitted from the second grating, focusing the display light onto the retina of the human eye for a clearer display. Attached Figure Description

[0043] Figure 1 A schematic structural diagram of a display optical system provided in an embodiment of this application;

[0044] Figure 2 A schematic structural diagram of a nanostructure provided in this application embodiment;

[0045] Figure 3 A schematic spectral diagram of a nanostructure provided for an embodiment of this application;

[0046] Figure 4 A schematic structural diagram of another display optical system provided in the embodiments of this application;

[0047] Figure 5 An optical simulation diagram provided for an embodiment of this application;

[0048] Figure 6 A schematic structural diagram of another display optical system provided in the embodiments of this application;

[0049] Figure 7 A schematic structural diagram of another display optical system provided in the embodiments of this application;

[0050] Figure 8 A schematic structural diagram of a display device provided in an embodiment of this application;

[0051] Figure 9 A schematic simulation diagram of a display device provided for an embodiment of this application;

[0052] Figure 10 This is a schematic structural diagram of a display device provided in an embodiment of this application. Detailed Implementation

[0053] To better understand the technical solutions provided in the embodiments of this specification, the technical solutions of the embodiments of this specification will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this specification and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this specification, rather than limitations on the technical solutions of this specification. In the absence of conflict, the embodiments of this specification and the technical features in the embodiments can be combined with each other.

[0054] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The term "two or more" includes two or more cases.

[0055] Augmented reality (AR) technology is a technique that cleverly integrates virtual information with the real world. It simulates computer-generated text, images, 3D models, music, videos, and other virtual information, and then applies them to the real world. The two types of information complement each other, thereby "enhancing" the real world. However, existing AR display technologies, in order to improve the quality of the display, need to display the virtual image at infinity. This makes it unclear to the human eye when actually viewing it and is very likely to cause visual fatigue.

[0056] In view of this, embodiments of this application provide a display optical system that can improve display clarity.

[0057] A first aspect of this application provides a display optical system. Figure 1 This is a schematic structural diagram of a display optical system provided in an embodiment of this application. Figure 1As shown, the display optical system includes a light source 100, a first grating 200, an optical waveguide structure 300, a second grating 400, and a first optical lens 500. The light source 100 may include a display screen, and the display light emitted from the light source 100 can form image information. The first grating 200 is located on the light-emitting side of the light source 100. The first grating 200 couples the display light emitted from the light source 100 into the optical waveguide structure 300, which can be used for total internal reflection transmission of the display light. The optical waveguide structure 300 is disposed on the side of the first grating 200 away from the light source 100. The side of the optical waveguide structure 300 closest to the first grating 200 includes an incident light region 310 and an exit light region 320. The incident light region 310 and the exit light region 320 are located on opposite sides of the optical waveguide structure 300, and the incident light region 310 and the exit light region 320 do not overlap. The first grating 200 is located in the light-incident region 310 of the optical waveguide structure 300, and the second grating 400 is located in the light-outceasing region 320 of the optical waveguide structure 300. The orthographic projection of the first grating 200 onto the optical waveguide structure 300 covers the light-incident region 310, and the orthographic projection of the second grating 400 onto the optical waveguide structure 300 covers the light-outceasing region 320. The first grating 200 can periodically spatially modulate the amplitude and phase of the display light, dividing the display light into diffracted light of various orders, so that the display light exits the optical waveguide structure 300 at a certain diffraction angle. Similarly, the second grating 400 can periodically spatially modulate the display light exiting the optical waveguide structure 300 again, so that the light after total internal reflection enters the first optical lens 500 at a certain diffraction angle. The first optical lens 500 is located in the light-outceasing region 320 of the optical waveguide structure 300, and is positioned closer to the human eye 600. The second grating 400 is disposed between the first optical lens 500 and the optical waveguide structure 300, and the first optical lens 500 and the second grating 400 can be fitted together without gaps. The first optical lens 500 may include a superlens, which may be a negative lens. The negative lens can modulate the phase and amplitude of the light field of the display light coupled out of the second grating 400, so that the backward extension of the display light converges on the retina of the human eye 600, making the display image clearer when the human eye 600 views it.

[0058] For example, the first optical lens includes a first nanostructure layer and a first substrate. The first nanostructure layer is disposed on the side of the first substrate away from the second grating. The first substrate and the second grating are bonded together without gaps. The first nanostructure layer includes multiple micro-nano structures, all of which are on the subwavelength scale. These micro-nano structures are lightweight, small in size, have high transmittance, and are easy to integrate. By using multiple subwavelength micro-nano structures, the optical system can be integrated into a thinner and lighter form factor, resulting in a smaller product. Simultaneously, it modulates the amplitude, phase, and polarization of the display light emitted from the second grating, focusing the display light onto the retina of the human eye, thus achieving a clearer display image.

[0059] For example, a superlens utilizes the principle of light diffraction and intricate microstructure design. By precisely controlling the size, morphology, and periodicity of subwavelength micro / nano structures, the diffraction angle and phase difference can be controlled to achieve the focusing function of a lens, enabling panchromatic focusing of light within the visible light spectrum. Furthermore, superlenses possess focusing capabilities exceeding the diffraction limit, enabling high-resolution imaging.

[0060] For example, display optical systems can be applied to AR products such as AR glasses, AR helmets, and AR screens. In AR glasses or other eyewear applications, the display light source can be positioned on the temples of the AR glasses, and the first grating, waveguide structure, second grating, and first optical lens constitute the AR lens. In AR helmet applications, the display light source can be positioned on both sides of the helmet visor, and the first grating, waveguide structure, second grating, and first optical lens constitute the helmet visor. In AR screen applications, the display light source can be positioned directly in front of the screen, and the first grating, waveguide structure, second grating, and first optical lens constitute the screen. By applying display optical systems to different AR products, a clear display image can be provided to the user.

[0061] Traditional display systems typically use geometric lenses, which control the refraction and focusing of light by optimizing parameters such as the curvature, surface shape, and materials of the lenses. Their imaging performance is limited by the constraints of processing size and surface shape, which can easily lead to virtual images being displayed at infinity. This makes the images unclear to the human eye and can easily cause visual fatigue.

[0062] The display optical system provided in this application embodiment features a first grating on one side of the light-incident area of ​​an optical waveguide structure, a second grating on the light-exit area, a light source positioned corresponding to the light-incident area, and the human eye located in the light-exit area. The first grating couples the display light emitted from the light source into the optical waveguide structure, where it undergoes total internal reflection and exits from the light-exit area. The second grating couples the total internal reflection-reflected display light out of the optical waveguide structure. By placing a first optical lens in the light-exit area of ​​the optical waveguide structure facing the human eye, and by employing multiple subwavelength micro-nano structures, the optical system can be integrated into a thinner and lighter form factor, resulting in a smaller overall product size. Simultaneously, it modulates the amplitude, phase, and polarization of the display light emitted from the second grating, focusing the display light onto the retina of the human eye for a clearer display.

[0063] For example, the first grating and the second grating can be seamlessly attached to the light-incident region 310 and the light-outcident region 320 of the optical waveguide structure, respectively, and the first optical lens is seamlessly attached to the second grating, so that the thickness of the integrated optical system is in the micrometer range and the focal length of the optical system is also in the micrometer range, making the entire optical system product small in size and light in weight.

[0064] In some examples, reference Figure 1 The size of the first optical lens 500 in the first direction X is greater than or equal to the size of the second grating 400 in the first direction X, where the first direction X is the direction from the light-incident region 310 to the light-outceasing region 320. The orthographic projection of the second grating 400 onto the optical waveguide structure covers the light-outceasing region 320 of the optical waveguide structure. By setting the size of the first optical lens 500 in the first direction X to be greater than or equal to the size of the second grating 400 in the first direction X, the orthographic projection of the first optical lens 500 onto the optical waveguide structure 300 covers the light-outceasing region 320 of the optical waveguide structure, which can prevent leakage of display light emitted from the optical waveguide structure, thereby improving the light extraction efficiency of the display optical system.

[0065] In some embodiments, the first optical lens includes a first substrate and a plurality of nanostructure units, wherein the plurality of nanostructure units may be disposed on the first substrate.

[0066] In some examples, the first optical lens includes multiple nanostructure units and multiple first substrates. The multiple nanostructure units can also be disposed on multiple first substrates, where one first substrate may have one nanostructure unit, or multiple nanostructure units may be disposed on each first substrate. By disposing of multiple nanostructure units, individual modulation of different display light rays can be achieved, allowing the display light rays to be more precisely focused onto the retina of the human eye.

[0067] Figure 2A schematic structural diagram of a nanostructure provided for embodiments of this application. Exemplary examples include... Figure 2 As shown, the first nanostructure layer includes multiple nanocylinders 520 with different radii. These nanocylinders 520 are disposed on the first substrate 510. The different radii of the nanocylinders 520 correspond to different phases and amplitudes of the light emitted from the optical waveguide structure 300. An array of multiple nanocylinders 520 with different radii is arranged on the first substrate 510 to form a first optical lens 500 with a circular connecting plane. The display light emitted from the optical waveguide structure 300, after passing through the nanocylinders 520 with different radii, can obtain light fields with different phases and amplitudes. It can also pass through nanocylinders 520 with different heights to obtain light fields with different phases and amplitudes, thus focusing the display light onto the retina of the human eye 600, enabling the human eye to view a clear display image.

[0068] Figure 3 A schematic spectral diagram of a nanostructure provided for embodiments of this application. Exemplary, such as... Figures 2 to 3 As shown, the first optical lens is composed of a 520-array arrangement of nanocylinders of different radii. Figure 3 The horizontal axis, radius (nm), represents the radius of the nanocylinder 520, while the vertical axis represents the amplitude and phase distribution of the emitted light field. The emitted light field is the light field after the light passes through the first optical lens 500. The radius *r* and height *h* of the nanocylinder 520 can be sequentially scanned using the finite-difference time-domain (FDTD) method. The radius *r* ranges from 40 nm to 140 nm, and the height *h* ranges from 400 nm to 900 nm. This yields an emitted light field amplitude of 1 for all values, with the phase covering integer multiples of 2π. Specifically, curve K1 represents the emitted light field amplitude of 1 when the radius of the nanocylinder 520 is between 40 nm and 140 nm. Curve K2 represents the emitted light field phase covering integer multiples of 2π when the radius of the nanocylinder 520 is between 40 nm and 140 nm. Then, the phase information is calculated using the above formula, and the dimensions of the nanocylinder 520 are determined based on this phase information. The nanocylinders 520 are then arranged in an array to obtain a superlens with a circular connecting plane, thus realizing the function of a negative lens.

[0069] In some examples, the radius r of the nanocylinder 520 can be 50nm, 80nm, 100nm, or 130nm, and the amplitude of the emitted light field after passing through the first optical lens is 1, with the phase covering integer multiples of 2π. The height h of the nanocylinder 520 can be 500nm, 600nm, 700nm, or 800nm, and the amplitude of the emitted light field after passing through the first optical lens is 1, with the phase covering integer multiples of 2π. By adjusting the height h of the nanocylinder 520, the optical path of the display light passing through the nanocylinder 520 can be changed, thereby achieving modulation of the phase and amplitude of the emitted light field.

[0070] This application embodiment achieves modulation of the phase and amplitude of the display light emitted from the optical waveguide structure by adjusting the radius r or the height of the nanocylinder 520, and thus achieves high transmittance of the display light, thereby realizing a clear and bright image display.

[0071] For example, the phase distribution formula of the emitted light field after the light rays pass through the first optical lens 500 is as follows:

[0072]

[0073] Where φ1(x,y) represents the phase coordinates of the emitted light field at different positions after the light ray passes through the first optical lens 500. λ in The wavelength of the light emitted from the optical waveguide structure is defined by f1, which represents the focal length of the first optical lens. Multiple nanocylinders 520 are arranged in an array to form a circular first optical lens 500. The maximum diameter of the array of nanocylinders 520 is the diameter of the circular first optical lens 500. Here, r1 represents the radial coordinate position of the nanocylinders 520 within the first optical lens 500 (i.e., the radius coordinate position of the nanocylinders 520), x represents the abscissa position of the nanocylinders 520 within the first optical lens 500 (i.e., the abscissa position of the nanocylinders 520 with the center of the circular first optical lens 500 as the origin), and y represents the ordinate position of the nanocylinders 520 within the circular first optical lens 500 (i.e., the ordinate position of the nanocylinders 520 with the center of the circular first optical lens 500 as the origin). By adjusting the radius or height of the nanocylinders 520, the phase and amplitude of the light field emitted from the optical waveguide structure 300 can be modulated to achieve a clear image display.

[0074] For example, the phase data of the first optical lens focusing can be calculated by setting the focal length f1 of the first optical lens and the radius r of the nanocylinder. When the first optical lens is a superlens and the focal length f1 is -4m, the first optical lens can image the image at infinity emitted through the optical waveguide structure onto a distance of 4m from the human eye, making the image clearer.

[0075] In some examples, the first nanostructure layer may include an array of multiple nanocubes or multiple nanocubes arranged in an array. By adjusting the length, width, and height of the cuboids and cubes, the phase and amplitude of the emitted light field can be modulated.

[0076] Figure 4 This is a schematic structural diagram of another display optical system provided in an embodiment of this application. An example is shown below. Figure 4As shown, the display optical system also includes a second optical lens 700, located on the side of the optical waveguide structure 300 opposite to the first optical lens 500. The first optical lens 500 is a negative lens, which diverges the light beam. The second optical lens 700 may include a positive lens, which converges the light beam. The orthographic projection of the second optical lens 700 onto the optical waveguide structure 300 overlaps with the orthographic projection of the first optical lens 500 onto the optical waveguide structure 300. This overlap can be complete or partial. Both the second and first optical lenses converge light, and the converging and diverging effects of the positive and negative lenses cancel each other out. By using the second optical lens 700, the first optical lens 500 can be corrected or compensated for, preventing the influence of ambient light on the imaging and improving the user experience.

[0077] For example, the second optical lens 700 and the first optical lens 500 are the same type of superlens. The radius and height ranges of the second optical lens 700 are the same as those of the first optical lens 500. The second optical lens 700 includes a second nanostructure layer and a second substrate. The second nanostructure layer is disposed on the side of the second substrate near the optical waveguide structure 300, and the second nanostructure layer may include nanocylinders 520.

[0078] For example, the phase distribution formula of the emitted light field after the light rays pass through the second optical lens 700 is as follows:

[0079]

[0080] in, This represents the phase coordinates of different positions in the emitted light field after ambient light or display light passes through the second optical lens 700. λ inThe wavelength of the light emitted from the optical waveguide structure 300 is represented by f2, and the focal length of the second optical lens 700 is represented by f2. Multiple nanocylinders 520 are arranged in an array to form a circular second optical lens 700. The maximum diameter of the array of nanocylinders 520 is the diameter of the circular second optical lens 700. r2 represents the radial coordinate position of the nanocylinders 520 within the circular second optical lens 700, i.e., the radius coordinate position of the nanocylinders 520. x represents the abscissa position of the nanocylinders 520 within the second optical lens 700, i.e., the abscissa position of the nanocylinders 520 with the center of the circular second optical lens 700 as the origin. y represents the ordinate position of the nanocylinders 520 within the circular second optical lens 700, i.e., the ordinate position of the nanocylinders 520 with the center of the circular second optical lens 700 as the origin. The phase and amplitude of the emitted light field from the optical waveguide structure 300 can be modulated by adjusting the radius or height of the nanocylinder 520, thereby achieving a clear image display.

[0081] Schematic illustration: FDTD scanning shows that the display light emitted from the optical waveguide structure 300, after passing through nanocylinders 520 with a radius ranging from 40nm to 140nm and a height ranging from 400nm to 900nm, exhibits an amplitude of 1 and a phase covering integer multiples of 2π. The nanocylinders 520 are then arranged in an array to form a second optical lens 700 with a circular connecting plane, thus achieving the function of a positive lens.

[0082] Figure 5 An optical simulation diagram provided for an embodiment of this application. For example, as shown... Figure 5 As shown, the horizontal and vertical axes characterize the size of the focused spot S of the second optical lens 700. The horizontal dimension of the spot ranges from -2μm to 2μm, and the vertical dimension of the spot S ranges from 10μm to 15μm. The smaller the horizontal and vertical dimensions of the spot S, the better the focusing effect of the spot, and the better the correction or compensation effect of the second optical lens 700 on the first optical lens 500.

[0083] For example, refer to Figure 4The refractive power of the first optical lens 500 and the second optical lens 700 can be designed based on a human eye's myopia of 600 diopters, where the refractive power is the reciprocal of the image distance. Both the first optical lens 500 and the second optical lens 700 can be superlenses, with the first optical lens 500 being a negative lens and the second optical lens 700 a positive lens. If the absolute values ​​of the refractive powers of the first optical lens 500 and the second optical lens 700 are equal, the effects of the positive and negative lenses cancel each other out, and will not affect the imaging of the external environment. If the absolute value of the refractive power of the first optical lens 500 is greater than that of the second optical lens 700, myopia can be corrected. If the absolute value of the refractive power of the first optical lens 500 is less than that of the second optical lens 700, hyperopia can be corrected. This allows for adjustments based on the user's myopia or hyperopia, ensuring both clear image display and a form similar to myopia or hyperopia glasses. This meets the viewing needs of different users and enhances the user experience.

[0084] The superlens provided in this application embodiment can calculate the phase distribution of the superlens based on the actual required focal length, and then set the radius of the nanocylinder 520 that can adjust this phase distribution accordingly, thereby realizing lenses with different focal lengths and different diopter designs to achieve system diversity of optical display systems.

[0085] Figure 6 This is a schematic structural diagram of another display optical system provided in an embodiment of this application. For example... Figure 6 As shown, the display optical system also includes a collimating lens group 800, located between the light source 100 and the first grating. The collimating lens group 800 includes at least one collimating lens. The light source 100 includes a display screen for providing image information. The collimating lens group 800 can collimate the display light emitted from the display screen into parallel light. The first grating 200 couples the parallel light into the optical waveguide structure 300. After total internal reflection within the optical waveguide structure 300, the second grating 400 couples the parallel light out and transmits it to the first optical lens 500. The first optical lens 500 is a negative lens that can diverge the parallel light rays, with its backward extension forming the focal point. This focal point is located at a comfortable viewing distance for the human eye 600. The focal point can be located on the retina of the human eye 600 or at a distance where the human eye 600 can clearly observe it. The collimating lens group 800 can include a single collimating lens, or it can include a combination of multiple collimating lenses to achieve different collimation effects.

[0086] Figure 7 This is a schematic structural diagram of another display optical system provided in an embodiment of this application. (See diagram below.) Figure 7As shown, exemplarily, the display optical system also includes a third optical lens 900, located between the first grating 200 and the light source 100. The orthographic projection of the first grating 200 onto the optical waveguide structure 300 falls within the orthographic projection of the third optical lens 900 onto the optical waveguide structure 300. The third optical lens 900 can replace the collimating lens group 800. The third optical lens 900 is used to focus the display light emitted from the light source 100 onto the first grating 200. The first grating 200 periodically modulates the light emitted from the third optical lens 900, causing the display light to exit onto the optical waveguide structure 300 at a certain diffraction angle. The third optical lens 900, the first optical lens 500, and the second optical lens 700 can all be the same type of superlens. By setting one or more superlenses in the optical system, panchromatic focusing of light within the visible light spectrum is achieved. Using the same type of superlens to achieve the focusing function ensures that the human eye 600 can see a clear display image while making the optical display system thinner and lighter.

[0087] In some examples, the third optical lens 900 includes a third nanostructure layer and a third substrate. The third nanostructure layer is located on the side of the third substrate closer to the collimating lens group, and may include nanocylinders 520. The nanocylinders of the first optical lens 500 are positioned towards the human eye 600, the nanocylinders 520 of the second optical lens 700 are positioned towards the optical waveguide structure 300, and the nanocylinders 520 of the third optical lens 900 are positioned towards the first grating. The first optical lens 500 is a negative lens, and the second optical lens 700 and the third optical lens 900 are positive lenses. The light source 100 is positioned on the focal plane of the third optical lens 900. The third optical lens 900 can collimate the light emitted from the light source 100 to accurately direct the light emitted from the light source onto the first grating, thereby improving the clarity and light emission efficiency of the displayed image.

[0088] In some embodiments, the size of the third optical lens 900 in the first direction X is smaller than that of the first optical lens 500 in the first direction X. The orthographic projection of the third optical lens 900 on the optical waveguide structure 300 does not overlap with the orthographic projection of the first optical lens 500 on the optical waveguide structure 300. The third optical lens 900 is located in the light-incident region 310 of the optical waveguide structure 300. After focusing the light emitted from the light source 100 onto the first grating 200, the light is coupled into the optical waveguide structure 300 via the first grating 200. The first optical lens 500 is located in the light-outceasing region 320 of the optical waveguide structure 300. The display light that undergoes total internal reflection within the optical waveguide structure 300 is coupled out via the second grating 400 and transmitted to the first optical lens 500. The first optical lens 500 modulates the phase and amplitude of the light field of the display light coupled out of the second grating 400 to focus the display light onto the retina of the human eye 600, so that the human eye 600 can observe a clear display image.

[0089] For example, the size of the third optical lens 900 in the first direction X can be greater than or equal to the size of the light source 100 in the first direction X, where the size can be the width dimension in the first direction X. The third optical lens 900 can focus all the light emitted from the light source 100 onto the first grating, preventing light leakage and improving the light extraction efficiency of the light source 100. Since the size of the third optical lens 900 in the first direction X is larger than the size of the first grating in the first direction X, display light from multiple directions can be coupled into the optical waveguide structure 300 via the first grating 200, improving the utilization rate of the display light.

[0090] In some embodiments, the first grating 200 includes a surface-embossed diffraction grating or a holographic diffraction grating, and the second grating 400 includes a surface-embossed diffraction grating or a holographic diffraction grating. A surface-embossed diffraction grating can be a grating with periodic etched lines or grooves formed on the surface of glass or other optical materials. A holographic diffraction grating is a grating fabricated using holographic photography. The first grating 200 can periodically spatially modulate the amplitude or phase of the display light emitted from the light source 100, or simultaneously periodically spatially modulate the amplitude or phase of the display light emitted from the light source 100, dividing the display light into diffracted light of various orders, which exit the optical waveguide structure 300 at a certain diffraction angle. Similarly, the second grating 400 can periodically spatially modulate the amplitude or phase of the display light after total internal reflection through the optical waveguide structure 300, or simultaneously periodically spatially modulate the amplitude or phase of the display light, dividing the display light into diffracted light of various orders, which then exit to the first optical lens 500 at a certain diffraction angle.

[0091] For example, the relationship between the diffraction order (m), diffraction wavelength (λ), incident angle (α), diffraction angle (β), and grating constant (d) of the grating is: mλ=d(sinα±sinβ), where m can take values ​​of 0, ±1, ±2, etc., and the corresponding spectra are called the zero-order spectrum, first-order spectrum, second-order spectrum, etc. By optimizing the height, tilt angle, and duty cycle of the first grating 200 or the second grating 400, or the refractive index of the material, the diffraction efficiency of the -1st order can be made higher, reaching 90% or more, thereby improving the diffraction efficiency of the first grating 200 and the second grating 400, and thus improving the light extraction efficiency of the display optical system.

[0092] Figure 8 This is a schematic structural diagram of a display device provided in an embodiment of this application. Figure 9 This is a schematic simulation diagram of a display device provided for an embodiment of this application. For example, as shown... Figure 8As shown, the first grating 200 is a surface-relief diffraction grating. 'a' represents the orthographic projection width of the relief structure 410 onto the waveguide structure 300, 'd' represents the spacing between two adjacent relief structures 410, the ratio of 'a' to 'b' is the duty cycle, 'b' represents the period of the surface-relief diffraction grating (ranging from 400 nm to 500 nm), and 'H' represents the height of the surface-relief diffraction grating (ranging from 300 nm to 500 nm). 'n1' represents the refractive index of the waveguide structure 300, 'n3' is the refractive index of the relief structure 410, and 'n2' is the air refractive index. The order n3 > n2 > n1 ensures that more light rays are coupled into the waveguide structure 300. The material of the surface-relief diffraction grating is TiO2, and the tilt angle 'θ' ranges from 30° to 45°. Optimization simulations were performed using FDTD (Finite-Difference Time-Domain) software, and the results are as follows: Figure 9 As shown, the horizontal axis represents the duty cycle of the surface-embossed diffraction grating, and the vertical axis represents its diffraction efficiency. Curve K3 shows that when the duty cycle of the surface-embossed diffraction grating is 0.5, the -1st order diffraction efficiency is the highest, reaching 90%. Curve K4 shows that when the duty cycle of the surface-embossed diffraction grating is 0.5, the 0th order diffraction efficiency is the lowest, approaching 0. Curve K5 shows that when the duty cycle of the surface-embossed diffraction grating is 0.5, the 1st order diffraction efficiency is the lowest, approaching 0.

[0093] In some examples, the first grating 200 is circular, and the second grating 400 is square. The diameter of the second grating is larger than the side length of the square first grating, and the projected area of ​​the second grating on the optical waveguide structure is larger than the projected area of ​​the first grating on the same structure. The diameter of the first grating 200 can be 2.5 mm or 3 mm. The side length of the second grating 400 can be 22 mm or 24 mm.

[0094] In some examples, the first grating is square, and the second grating is circular. The diameter of the second grating is larger than the side length of the square first grating, and the projected area of ​​the second grating on the optical waveguide structure is larger than the projected area of ​​the first grating on the same structure. The side length of the first grating can be 2.5 mm or 3 mm. The diameter of the second grating can be 22 mm or 24 mm.

[0095] In some examples, the preset distance between the first grating 200 and the second grating 400 ranges from 20mm to 30mm. Illustratively, the preset distance between the first grating 200 and the second grating 400 is 23mm, 25mm, or 28mm.

[0096] For example, the orthographic projection of the light source 100 onto the optical waveguide structure 300 falls within the orthographic projection of the first grating 200 onto the optical waveguide structure 300, and the orthographic projection of the second grating onto the optical waveguide structure 300 falls within the orthographic projection of the first optical lens onto the optical waveguide structure 300. The orthographic projection area of ​​the second grating 400 onto the optical waveguide structure 300 is larger than the orthographic projection area of ​​the first grating 200 onto the optical waveguide structure 300. The size of the first grating is matched to the size of the light source to couple all the display light emitted from the light source into the optical waveguide structure 300. The size of the second grating 400 is matched to the size of the first optical lens 500 to converge all the display light emitted from the optical waveguide structure 300 to the human eye, preventing light leakage and improving the brightness of the display screen. Setting a preset distance between the first grating 200 and the second grating 400 allows light to transmit within the preset distance, reducing light loss and improving the brightness of the display screen.

[0097] For example, the optical waveguide structure 300 is made of glass, and the thickness of the optical waveguide structure 300 in the second direction ranges from 2.5mm to 3.5mm. The thickness of the optical waveguide structure can be set according to the actual display requirements. The optical waveguide structure 300 plays the role of total internal reflection and light refraction to achieve different display effects.

[0098] In some examples, the first grating 200 may include a micro / nano structure array, the second grating 400 may include a micro / nano structure array, and the first optical lens 500, the second optical lens 700, and the third optical lens 900 may all include micro / nano structures. Since the size of the micro / nano structures is at the nanometer scale, their weight is negligible compared to the combined lenses. The amplitude of the micro / nano structures is approximately 1, and their transmittance is close to 100%. In contrast, the transmittance of a single geometric lens is around 99.5%, and the more lenses there are, the lower the transmittance.

[0099] In some examples, the dimensions of the first grating 200 in the second direction Y are the same as those of the second grating 400 in the second direction Y, where the dimension can be the thickness dimension in the second direction Y. The second direction Y is perpendicular to the first direction X. By setting the dimensions of the first and second gratings to be the same, product consistency can be improved and processing difficulty reduced.

[0100] For example, the thickness of the first optical lens 500 in the second direction Y is the same as the thickness of the second optical lens 700 in the second direction Y, and the thickness of the second optical lens 700 in the second direction Y is the same as the thickness of the third optical lens 900 in the second direction Y. By adjusting the thickness dimensions of the three optical lenses, the consistency of product processing is improved and the processing difficulty is reduced.

[0101] The display optical system provided in this application embodiment, through the arrangement of a first optical lens, a second optical lens, a third optical lens, a first grating, and a second grating, enables display light from infinity to be focused at a comfortable viewing position for the human eye, thereby improving viewing comfort and expanding the application scenarios of AR products. The first optical lens, second optical lens, third optical lens, first grating, and second grating can all be directly attached to the waveguide sheet, making the optical system thinner and lighter.

[0102] A second aspect of this application provides a display device. Figure 10 This is a schematic structural diagram of a display device provided in an embodiment of this application. For example,... Figure 10 As shown, the display device 2000 includes a display optical system 1000 as described in the first aspect.

[0103] For example, the display device may include AR glasses, AR helmets or other head-mounted display products, as well as AR screens, AR partitions, AR signs, AR navigation maps or other products that can be displayed in AR.

[0104] The display optical system provided in this application embodiment features a first grating on one side of the light-incident region of an optical waveguide structure, a second grating on the light-exit region, a light source positioned corresponding to the light-incident region, and the human eye located in the light-exit region. The first grating couples the display light emitted from the light source into the optical waveguide structure, where it undergoes total internal reflection and exits from the light-exit region. The second grating couples the total internal reflection-reflected display light out of the optical waveguide structure. By placing a first optical lens in the light-exit region of the optical waveguide structure facing the human eye, the phase and amplitude of the light field emitted from the optical waveguide structure are modulated. This allows for focusing a virtual image at infinity onto the retina of the human eye, regardless of manufacturing size limitations, resulting in a clearer display and reducing eye strain.

[0105] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0106] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

[0107] Although preferred embodiments have been described in this specification, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this specification.

[0108] Obviously, those skilled in the art can make various modifications and variations to this specification without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims and their equivalents, this specification is also intended to include such modifications and variations.

Claims

1. A display optical system, characterized in that, include: A light source, used to emit display light; A first grating is disposed on the light-emitting side of the light source; An optical waveguide structure is disposed on the side of the first grating away from the light source. The side of the optical waveguide structure close to the first grating includes an incident light region and an exit light region. The incident light region and the exit light region do not overlap. The orthographic projection of the first grating onto the optical waveguide structure covers the incident light region. The second grating and the first grating are disposed on the same side of the optical waveguide structure. The orthographic projection of the second grating on the optical waveguide structure covers the light-emitting area. The first grating and the second grating are spaced apart by a preset distance. A first optical lens, and a second grating located between the first optical lens and the optical waveguide structure, wherein the orthographic projection of the second grating on the optical waveguide structure falls within the orthographic projection of the first optical lens on the optical waveguide structure; The first optical lens includes a first nanostructure layer and a first substrate, wherein the first nanostructure layer is disposed on the side of the first substrate away from the second grating.

2. The display optical system according to claim 1, characterized in that, The first optical lens includes multiple nanounit structures and multiple first substrates; The nanounit structure is configured one-to-one with the first substrate; or... The first optical lens includes a plurality of the nanounit structures and a first substrate; A plurality of the nanounit structures are disposed on the first substrate.

3. The display optical system according to claim 1, characterized in that, The first nanostructure layer includes multiple nanocylinders with different radii, and the different radii of the nanocylinders correspond to different phases and different amplitudes of the light field emitted from the optical waveguide structure.

4. The display optical system according to claim 3, characterized in that, The first nanostructure layer comprises an array of multiple nanocubes and / or nanocubes.

5. The display optical system according to claim 1, characterized in that, The size of the first optical lens in the first direction is greater than or equal to the size of the second grating in the first direction, wherein the first direction is the direction from the light-incident region to the light-outceasing region.

6. The display optical system according to any one of claims 1 to 5, characterized in that, Also includes: The second optical lens is located on the side of the optical waveguide structure opposite to the first optical lens, and the orthographic projection of the second optical lens on the optical waveguide structure overlaps with the orthographic projection of the first optical lens on the optical waveguide structure.

7. The display optical system according to claim 6, characterized in that, Also includes: A collimating lens group is located between the light source and the first grating, wherein the collimating lens group includes at least one collimating lens; The third optical lens is located between the collimating lens group and the light source, and the orthographic projection of the first grating on the optical waveguide structure falls within the orthographic projection of the third optical lens on the optical waveguide structure; And / or, The third optical lens comprises a nanocylinder; and / or, The second optical lens comprises a nanocylinder.

8. The display optical system according to claim 7, characterized in that, The third optical lens has a smaller size in the first direction than the first optical lens in the first direction, where the first direction is the direction from the light-incident region to the light-outceasing region. The orthographic projection of the third optical lens onto the optical waveguide structure does not overlap with the orthographic projection of the first optical lens onto the optical waveguide structure.

9. The display optical system according to claim 7, characterized in that, The radius of the nanocylinders ranges from 40 nm to 140 nm; and / or, The height of the nanocylinders ranges from 400 nm to 900 nm.

10. The display optical system according to any one of claims 1 to 5, characterized in that, The first grating includes a surface-embossed diffraction grating or a volume holographic diffraction grating; and / or, The second grating includes a surface relief diffraction grating or a volume holographic diffraction grating; And / or, The tilt angle of the surface-embossed diffraction grating ranges from 30° to 45°; and / or, The height range of the surface relief diffraction grating is 300 nm to 500 nm.

11. The display optical system according to claim 10, characterized in that, The first grating includes an array of micro / nano structures; and / or, The second grating includes a micro / nano structure array, wherein the dimensions of the first grating in the second direction are the same as the dimensions of the second grating in the second direction, wherein the second direction is perpendicular to the first direction.

12. The display optical system according to claim 10, characterized in that, The projected area of ​​the second grating on the optical waveguide structure is larger than the projected area of ​​the first grating on the optical waveguide structure; and / or, The preset distance between the first grating and the second grating is in the range of 20mm to 30mm.

13. A display device, characterized in that, include: The display optical system as described in any one of claims 1 to 12.

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