An augmented reality near-eye display system based on pixelated harmonic diffraction elements

Abstract

The present invention belongs to the field of display technology, and specifically provides an augmented reality near-eye display system based on a pixelated harmonic diffraction element, comprising a closely arranged color transparent display screen and a pixelated harmonic diffraction element, wherein the color transparent display screen is composed of a plurality of image pixels and is used to display a target image, and emits light containing target image information to be incident on the pixelated harmonic diffraction element; the pixelated harmonic diffraction element is generated by discretizing the harmonic diffraction element pixel by pixel, and is composed of a plurality of discrete structural pixels, and the structural pixels are aligned one by one with the image pixels on the color transparent display screen; each structural pixel on the pixelated harmonic diffraction element directionally diffracts the light emitted by the aligned image pixel on the color transparent display screen to the optical center of the lens of the human eye and finally reaches the retina, thereby forming a retinal projection color near-eye display effect, avoiding the complex projection optical path in the existing augmented reality near-eye display system, and having the advantages of simple structure, small size and light weight.

Description

Technical Field

[0001] The present invention belongs to the field of display technology, and in particular relates to an augmented reality near-eye display system based on a pixelated harmonic diffraction element. Background Art

[0002] Augmented reality near-eye displays (ARNs) are new interactive windows that integrate virtual digital information with real physical information. Due to their unique characteristics of virtual-reality fusion, three-dimensional immersion, and real-time interaction, they are widely used in military training, industrial manufacturing, surgical navigation, and other fields, and are expected to become the next generation of human-computer interaction display platforms. Optical modules are the core components of AR NEDs, and their performance is a key factor directly affecting imaging quality and interactive experience. The design of optical modules must take into account both the visual characteristics of the human eye and ergonomic requirements, comprehensively considering important indicators such as field of view, eye movement range, light efficiency, angular resolution, component transmittance, distortion, volume, and quality. From the current state of technological development, AR NED technologies mostly use a binocular parallax stereoscopic perspective display mode, integrating real scenes with virtual images through different types of optical modules (mainly free-form optical components / geometric waveguides / diffraction waveguides / holographic waveguides). However, for consumer applications, augmented reality near-eye display optical modules still face common limitations. For example, free-form surface designs trade off field of view against size, while optical waveguide structures enable thin and lightweight systems but suffer from a limited field of view. Furthermore, there are issues such as poor display quality, a narrow depth range, and visual fatigue caused by convergence and focusing conflicts. Therefore, overcoming these limitations through innovative optical architectures, innovative model designs, and the use of novel optical components will be crucial. A metasurface is an array of subwavelength electromagnetic control units arranged in a two-dimensional plane. It can arbitrarily manipulate the amplitude, phase, polarization, and frequency parameters of light waves. With its ultra-thin, planar, low-loss, and easy-to-integrate advantages, it is widely considered a next-generation optical component. Leveraging its powerful light field control capabilities and unique advantages of being thin, lightweight, and flat, metasurfaces offer new solutions to overcome the bottlenecks of existing near-eye display systems. Therefore, metasurface optical technology is expected to become a powerful platform for researching and improving augmented reality near-eye displays.

[0003] Researchers both domestically and internationally have explored and experimented with the application of metasurfaces in the field of augmented reality near-eye displays. For example, in 2017, C. Hong et al. from the University of Washington first proposed a design for an augmented reality near-eye display system based on a microdisplay and a metasurface. Compared to near-eye display systems based on free-form mirrors, this system boasts advantages such as a small size and a wide field of view. However, this system only responds to red light and cannot display color. Subsequently, in 2021, E. Bayati et al. from the same group at the University of Washington further improved on this design, proposing an achromatic augmented reality near-eye display system based on a composite metasurface. The metasurface closest to the eye achieves an achromatic phase distribution for reflecting light from the display, while the other metasurface is used to avoid distortion of the real light field information caused by the achromatic metasurface. This system offers advantages such as a large field of view, a small size, and achromatic aberration. However, the complex internal structure and extremely small feature sizes of the composite metasurface make its fabrication process complex and expensive. Furthermore, the two metasurfaces require precise alignment during fabrication, further increasing the complexity of the composite metasurface's fabrication. In addition, Chinese patent 201811187305.2 discloses an augmented reality near-eye display system based on an ultra-microstructure, wherein the ultra-microstructure has a semi-transparent and semi-reflective function, which is used to reflect the light emitted by the microdisplay and converge it to the pupil of the human eye, thereby achieving the effect of augmented reality near-eye display. However, the above three schemes all adopt a reflective optical system design, resulting in a large space between the microdisplay and the metasurface, which hinders the further reduction of the volume of the near-eye display system. In addition, Chinese patent 202210019355.X discloses a metasurface micro-nano near-eye display based on retinal display, including a transparent micro-display image source, a metasurface micro-nano focusing lens group and a metasurface micro-nano compensation lens group, which has the advantages of large field of view and small volume. The metasurface micro-nano focusing lens group focuses the light beam information emitted by the transparent micro-display image source at the optical center of the human eye lens and ultimately reaches the retina for imaging; the metasurface micro-nano compensation lens group can offset the focusing effect of the metasurface micro-nano focusing lens group, allowing light emitted by objects in the real external environment to enter the human eye normally without lens effect after passing through the metasurface micro-nano compensation lens group and the metasurface micro-nano focusing lens group; the pixels of the transparent micro-display image source are composed of three sub-pixels of red, green, and blue. The nanopillar array of a single pixel on the metasurface micro-nano focusing lens layer corresponds to a pixel of the transparent micro-display image source, thereby achieving achromatic color display. However, the structure of the metasurface micro-nano lens group is complex and delicate, and in order to precisely modulate the phase, the length, width, and rotation angle of the nanopillars of different pixels must be different, which makes the preparation of this structure extremely difficult and the processing cost expensive.Furthermore, this solution achieves achromatic aberration by using a nanopillar array within a single metasurface pixel to modulate the phase of light emitted by the red, green, and blue sub-pixels, thereby suppressing chromatic aberration. However, micro-display image sources composed of multiple sub-pixels often have low resolution, making high-resolution display difficult. Furthermore, this solution struggles to achieve good achromatic aberration for micro-display image sources with single-pixel, broad-spectrum emission, significantly limiting its practicality. Based on this, an augmented reality near-eye display system based on pixelated harmonic diffraction elements is proposed. Summary of the Invention

[0004] The present invention mainly provides an augmented reality near-eye display system based on pixelated harmonic diffraction elements, which overcomes the common problems of high processing difficulty and high processing cost of achromatic metasurface optical devices used in augmented reality near-eye display systems at this stage. It aims to provide a low-cost, easy-to-process achromatic metasurface optical device, which can be used in conjunction with a color transparent display to achieve a large field of view, small volume, and achromatic augmented reality color near-eye display effect.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is:

[0006] An augmented reality near-eye display system based on a pixelated harmonic diffraction element comprises a color transparent display screen and a pixelated harmonic diffraction element arranged closely together, wherein the pixelated harmonic diffraction element is close to the human eye and the color transparent display screen is close to the real object.

[0007] The color transparent display screen is composed of a plurality of image pixels and is used to display a target image. Light containing target image information is emitted and incident on the pixelated harmonic diffraction element.

[0008] The pixelated harmonic diffraction element is generated by discretizing the harmonic diffraction element pixel by pixel, and is composed of a plurality of discrete structural pixels, and the structural pixels are aligned one by one with the image pixels on the color transparent display screen;

[0009] Each structural pixel on the pixelated harmonic diffraction element diffracts the light emitted by the image pixel on the aligned color transparent display screen in a directionally directed manner to the optical center of the lens of the human eye and ultimately to the retina, thereby forming the effect of retinal projection color near-eye display.

[0010] A further improvement is that the size of the structured pixel is equal to the size of the image pixel on the color transparent display screen, and the spacing between adjacent structured pixels is equal to the spacing between adjacent image pixels on the color transparent display screen.

[0011] A further improvement is that the design steps of the pixelated harmonic diffraction element are as follows:

[0012] S1: Determination of harmonic diffraction conditions: Determine the design main wavelength λ based on the luminous spectrum of the color transparent display m Harmonic diffraction coefficient P m Then, the harmonic diffraction condition is determined according to the harmonic diffraction achromatic principle, that is, the harmonic diffraction wavelength λ h Harmonic diffraction order P h :

[0013] λ m P m =λ h P h

[0014] S2: Phase calculation of the harmonic diffraction element: Establish the coordinate system of the display plane and the observation plane, record the distance between the two planes as d, record any position on the display plane as A(x,y,0), record the position of the optical center of the human eye lens on the observation plane as B(0,0,d), and then calculate the phase distribution of the harmonic diffraction element. for:

[0015]

[0016] Where mod(·) represents the remainder operation;

[0017] S3: Continuous morphology acquisition of harmonic diffraction element: Select the material of the harmonic diffraction element and calculate the refractive index n of the material. m Calculate the maximum structural height h of the harmonic diffraction element max for:

[0018]

[0019] Therefore, the height distribution h(x,y,0) of the harmonic diffraction element can be obtained as:

[0020]

[0021] That is the continuous morphology of the harmonic diffraction element;

[0022] S4: Stepping of harmonic diffraction elements: Establish a mapping relationship between the number of quantitative steps in the height of the harmonic diffraction element structure and the diffraction efficiency. Consider factors such as diffraction efficiency and processing accuracy to determine the number of steps N. Then, quantize the height distribution h(x, y, 0) of the harmonic diffraction element to obtain the stepped height distribution of the harmonic diffraction element. for:

[0023]

[0024] This is the multi-step morphology of the harmonic diffraction element, where round(·) represents the rounding operation;

[0025] S5: Discrete pixelation of harmonic diffraction element: Discrete the designed harmonic diffraction element according to the pixel size and pixel pitch of the color transparent display screen. Specifically, the color transparent display screen is used as a binary mask BM(x,y,0), that is, the element value corresponding to the coordinate within the image pixel area is 1, and the element value corresponding to the coordinate outside the image pixel area is 0. Then, the stepped height distribution of the harmonic diffraction element is used. Multiplying by the binary mask BM(x,y,0) can get the height distribution of the pixelated harmonic diffraction element for:

[0026]

[0027] At this point, the overall design of the pixelated harmonic diffraction element is completed.

[0028] A further improvement is that the light corresponding to the designed main wavelength and the harmonic diffraction wavelength emitted by each image pixel will propagate in the same direction after harmonic diffraction by the aligned structural pixels, thereby achieving an achromatic display effect.

[0029] A further improvement is that the color transparent display screen and the pixelated harmonic diffraction element both have the function of transmitting light emitted by real objects, so that the light emitted by real objects can also enter the human eye and eventually reach the retina, thereby realizing the superposition and fusion of the real object image and the image displayed on the color transparent display screen on the retina, forming the effect of augmented reality color near-eye display.

[0030] A further improvement is that the color transparent display screen is any one of an organic light emitting diode display, a micron-scale organic light emitting diode display, a micron-scale inorganic light emitting diode display, and a nanometer-scale inorganic light emitting diode display.

[0031] A further improvement is that the material of the pixelated harmonic diffraction element is quartz glass or K9 glass.

[0032] A further improvement is that the minimum feature size of the microstructure on the pixelated harmonic diffraction element is greater than 300 nm.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The augmented reality near-eye display system of the present invention is composed of two components, a color transparent display screen and a pixelated harmonic diffraction element, which are closely connected. This avoids the complex projection optical path of existing augmented reality near-eye display systems and has a simple structure, small size and light weight.

[0035] 2. The augmented reality near-eye display system of the present invention looks similar to ordinary eyeglass lenses, and the pixelated harmonic diffraction element is close to the side of the human eye, which effectively reduces the exit pupil distance and expands the field of view of the near-eye display;

[0036] 3. Compared with retinal projection display methods based on laser scanning technology, the structural pixels on the pixelated harmonic diffraction element of the present invention are aligned one-to-one with the image pixels on the transparent display screen, so that the light emitted by each image pixel on the color transparent display screen is directionally diffracted to the optical center of the human eye lens and ultimately reaches the retina, thus forming a retinal projection display effect, avoiding the safety issues of laser focusing on the optical center of the lens and improving the safety of use;

[0037] 4. The pixelated harmonic diffraction element of the present invention can guide light corresponding to the designed main wavelength and the harmonic diffraction wavelength in the same direction into the optical center of the human eye lens and ultimately onto the retina, thereby achieving an achromatic display effect. This solves the problem that existing metasurface micro-nano near-eye displays cannot adapt to micro-display image sources with single-pixel wide-spectrum luminescence.

[0038] 5. Compared with other metasurface optical devices used in augmented reality near-eye display systems, the pixelated harmonic diffraction element in the present invention has a larger characteristic size and does not require expensive electron beam lithography technology during processing, which helps to reduce processing difficulty and cost.

[0039] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of an augmented reality near-eye display system based on a pixelated harmonic diffraction element proposed by the present invention;

[0041] Figure 2 A schematic diagram of alignment between structural pixels on the pixelated harmonic diffraction element of the present invention and image pixels on a color transparent display screen;

[0042] Figure 3 This is a design flow chart of the pixelated harmonic diffraction element of the present invention;

[0043] Figure 4 A diagram showing the positional relationship between the display plane and the observation plane of the present invention;

[0044] Figure 5 Schematic diagram of light propagation of light of different wavelengths after passing through the pixelated harmonic diffraction element of the present invention;

[0045] Figure 6 is the height distribution of the pixelated harmonic diffraction element in a specific embodiment of the present invention;

[0046] Figure 7 This is a partially enlarged three-dimensional distribution diagram of a 2mm×2mm area in the center of a pixelated harmonic diffraction element in a specific embodiment of the present invention.

[0047] Among them, 1 is a color transparent display screen; 101 is an image pixel; 2 is a pixelated harmonic diffraction element; 201 is a structural pixel. DETAILED DESCRIPTION

[0048] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in various forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0049] Reference Figure 1-7 The present invention proposes an augmented reality near-eye display system based on pixelated harmonic diffraction elements. Figure 1 As shown, it includes a color transparent display screen 1 and a pixelated harmonic diffraction element 2;

[0050] The color transparent display screen 1 is composed of a plurality of image pixels 101 and is used to display a target image. The light rays containing target image information are emitted and incident on the pixelated harmonic diffraction element 2 .

[0051] The pixelated harmonic diffraction element 2 is generated by discretizing the harmonic diffraction element pixel by pixel, and can be regarded as consisting of a plurality of discrete structural pixels 201. The structural pixels 201 are aligned one by one with the image pixels 101 on the color transparent display screen 1, as shown in FIG. Figure 2 As shown, the size of the structure pixel 201 is equal to the size of the image pixel 101 on the color transparent display screen 1 , and the spacing between adjacent structure pixels 201 is equal to the spacing between adjacent image pixels 101 on the color transparent display screen 1 .

[0052] The design process of pixelated harmonic diffraction element 2 is as follows: Figure 3 The specific steps are as follows:

[0053] S1: Determination of harmonic diffraction conditions: Determine the design main wavelength λ based on the luminous spectrum of the color transparent display 1 m Harmonic diffraction coefficient P m Then, the harmonic diffraction condition is determined according to the harmonic diffraction achromatic principle, that is, the harmonic diffraction wavelength λ h Harmonic diffraction order P h :

[0054] λ m P m =λ h P h

[0055] S2: Phase calculation of harmonic diffraction element: Establish the coordinate system of display plane and observation plane, such as Figure 4As shown, the distance between the two planes is recorded as d, any position on the display plane is recorded as A(x,y,0), and the position of the optical center of the human eye lens on the observation plane is recorded as B(0,0,d). Then the phase distribution of the harmonic diffraction element is calculated. for:

[0056]

[0057] Wherein, mod(·) represents the remainder operation.

[0058] S3: Continuous morphology acquisition of harmonic diffraction element: Select the material of the harmonic diffraction element and calculate the refractive index n of the material. m Calculate the maximum structural height h of the harmonic diffraction element max for:

[0059]

[0060] Therefore, the height distribution h(x,y,0) of the harmonic diffraction element can be obtained as:

[0061]

[0062] That is the continuous morphology of the harmonic diffraction element.

[0063] S4: Stepping of harmonic diffraction elements: Establish a mapping relationship between the number of quantitative steps in the height of the harmonic diffraction element structure and the diffraction efficiency. Consider factors such as diffraction efficiency and processing accuracy to determine the number of steps N. Then, quantize the height distribution h(x, y, 0) of the harmonic diffraction element to obtain the stepped height distribution of the harmonic diffraction element. for:

[0064]

[0065] This is the multi-step morphology of the harmonic diffraction element, where round(·) represents a rounding operation.

[0066] S5: Discrete pixelation of harmonic diffraction element: Discrete the designed harmonic diffraction element according to the pixel size and pixel pitch of the color transparent display screen 1. Specifically, the color transparent display screen 1 is used as a binary mask BM(x, y, 0), that is, the element value corresponding to the coordinate within the image pixel 101 area is 1, and the element value corresponding to the coordinate outside the image pixel 101 area is 0. Then, the step height distribution of the harmonic diffraction element is used. Multiplying by the binary mask BM(x,y,0) can get the height distribution of the pixelated harmonic diffraction element for:

[0067]

[0068] At this point, the overall design of the pixelated harmonic diffraction element 2 is completed.

[0069] In a preferred embodiment, each structural pixel 201 on the pixelated harmonic diffraction element 2 directionally diffracts the light emitted by the image pixel 101 on the aligned color transparent display screen 1 to the optical center of the lens of the human eye and ultimately reaches the retina, thereby forming a retinal projection color near-eye display effect.

[0070] In a preferred embodiment, the pixelated harmonic diffraction element 2 is placed closely to the color transparent display screen 1, wherein the pixelated harmonic diffraction element 2 is close to the human eye side, and the color transparent display screen 1 is away from the human eye side, that is, close to the real object side.

[0071] In a preferred embodiment, Figure 5 As shown, light emitted by each image pixel 101 at the designed primary wavelength and harmonic diffraction wavelength propagates in the same direction after harmonic diffraction by the aligned structure pixels 201, thereby achieving an achromatic display effect. Light emitted by different image pixels 101 on the color transparent display 1 is directionally diffracted by the aligned structure pixels 201 and ultimately forms a viewpoint at the optical center of the human eye's lens, creating a retinal projection near-eye display effect.

[0072] In a preferred embodiment, the color transparent display screen 1 and the pixelated harmonic diffraction element 2 both have the function of transmitting light emitted by real objects, so that the light emitted by real objects can also enter the human eye and eventually reach the retina, thereby realizing the superposition and fusion of the real object image and the image displayed on the color transparent display screen 1 on the retina, thereby forming the effect of augmented reality color near-eye display.

[0073] In the above technical solution, the color transparent display screen 1 is any one of an organic light-emitting diode display (OLED), a micron-level organic light-emitting diode display (Micro-OLED), a micron-level inorganic light-emitting diode display (Micro-LED), and a nano-level inorganic light-emitting diode display (Nano-LED).

[0074] In a preferred embodiment, the material of the pixelated harmonic diffraction element 2 is quartz glass or K9 glass.

[0075] In a preferred embodiment, the minimum feature size of the microstructure on the pixelated harmonic diffraction element 2 is greater than 300 nm.

[0076] Based on the above implementation, the color transparent display screen 1 in this embodiment is composed of 1136×640 image pixels 101, each of which is 36μm×36μm in size, with the horizontal and vertical spacing between adjacent image pixels 101 being 40μm. The pixelated harmonic diffraction element 2 is then composed of 1136×640 different structural pixels 201, each of which is also 36μm×36μm in size, with the horizontal and vertical spacing between adjacent structural pixels 201 also being 40μm. The luminous spectrum of the color transparent display screen 1 covers the red, green, and blue bands. The spectral range with a normalized transmittance greater than 0.5 is designated as the highlight band. Thus, the highlight bands of the red, green, and blue spectra are 608-650nm, 505-550nm, and 438-465nm, respectively. The design main wavelength of the pixelated harmonic diffraction element 2 is set to 525nm, and the harmonic diffraction coefficient is 6. According to the corresponding formula, it can be calculated that when the harmonic diffraction order is 5, the harmonic diffraction wavelength is 630nm; when the harmonic diffraction order is 7, the harmonic diffraction wavelength is 450nm, so that after the directional diffraction of the pixelated harmonic diffraction element 2, the fifth-order diffraction light with a wavelength of 630nm, the sixth-order diffraction light with a wavelength of 525nm, and the seventh-order diffraction light with a wavelength of 450nm will propagate in the same direction into the optical center of the lens of the human eye and eventually reach the retina, thereby achieving an achromatic color display effect. The material of the pixel grating array device 2 is K9 glass with a refractive index of 1.523. It is assumed that the human eye is located on the central axis of the color transparent display screen 1 and the observation distance from the color transparent display screen 1 is 25mm. According to the calculation formula of the maximum structural height of the harmonic diffraction element, the maximum structural height h of the harmonic diffraction element can be calculated. max The quantized step number N of the harmonic diffraction element structure height is set to 256. Figure 3 After the design process of the pixelated harmonic diffraction element 2 shown in FIG. 1 , the height distribution of the designed pixelated harmonic diffraction element 2 can be obtained as shown in FIG. Figure 6 As shown, the locally enlarged three-dimensional distribution diagram of the 2mm×2mm area in the center of the pixelated harmonic diffraction element 2 is shown as Figure 7 At this point, the overall design of the pixelated harmonic diffraction element 2 is completed.

[0077] A preferred manufacturing process for the pixelated harmonic diffraction element 2 in this embodiment is as follows: first, the glass substrate is rigorously cleaned, and then photoresist is coated on the substrate surface by spin coating to form a uniform photoresist layer. Then, a pixelated harmonic diffraction element pattern is produced using laser direct write photolithography technology to form a photoresist mask. Then, the pattern of the above-mentioned photoresist mask is transferred using ion beam etching technology. After the etching is completed, a pixelated harmonic diffraction element pattern is formed on the surface of the glass substrate, namely, an etched element. Finally, the remaining photoresist on the top of the etched element is removed and cleaned, thereby completing the production of the pixelated harmonic diffraction element 2.

[0078] Afterwards, the manufactured pixelated harmonic diffraction element 2 and the color transparent display screen 1 are integrated and adjusted under a microscope. When it is observed that the structural pixels 201 on the pixelated harmonic diffraction element 2 are aligned one by one with the image pixels 101 on the color transparent display screen 1, the positions of the color transparent display screen 1 and the pixelated harmonic diffraction element 2 are fixed, and then they are bonded and cured with glue, thereby forming an augmented reality color near-eye display system based on the color transparent display screen and the pixelated harmonic diffraction element.

[0079] Light emitted by each image pixel 101 on the color transparent display 1 is directionally diffracted by the corresponding structural pixel 201 on the pixelated harmonic diffraction element 2. Light corresponding to the designed main wavelength and the harmonic diffraction wavelength propagates in the same direction, enters the optical center of the human eye's lens, and ultimately reaches the retina, thereby achieving an achromatic retinal projection color near-eye display. Simultaneously, light emitted by a real object enters the human eye through the color transparent display 1 and the pixelated harmonic diffraction element 2, ultimately reaching the retina to form an image of the real object. The real object image on the retina is superimposed and fused with the image displayed on the color transparent display 1, ultimately achieving an augmented reality color near-eye display.

[0080] In this embodiment, the display size of the color transparent display screen 1 is 45.44 mm × 25.6 mm, the observation distance is 25 mm, and the horizontal, vertical and diagonal field of view angles are calculated to be 84.53°, 54.22° and 92.42°, respectively, which illustrates that the augmented reality near-eye display system based on pixelated harmonic diffraction elements proposed in the present invention has the advantage of a large field of view angle.

[0081] In summary, the present invention discloses an augmented reality near-eye display system based on a pixelated harmonic diffraction element. In the present invention, the augmented reality near-eye display system is composed of only two components, a color transparent display screen and a pixelated harmonic diffraction element, which are closely attached to each other. The appearance is similar to that of ordinary glasses lenses, avoiding the complex projection light path, and has the advantages of small size, light weight, and large field of view. At the same time, since the pixelated harmonic diffraction element has achromatic characteristics, the system can achieve the effect of augmented reality color near-eye display. In addition, compared with other metasurface optical devices used for augmented reality near-eye display systems, the pixelated harmonic diffraction element in the present invention is a low-cost, easy-to-process metasurface optical device, which does not require expensive electron beam lithography technology during processing, thereby effectively reducing the processing difficulty and processing cost.

[0082] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An augmented reality near-eye display system based on pixelated harmonic diffraction elements, characterized in that: It includes a color transparent display screen and a pixelated harmonic diffraction element that are closely arranged, wherein the pixelated harmonic diffraction element is close to the human eye side and the color transparent display screen is close to the real object side; The color transparent display screen is composed of a plurality of image pixels and is used to display a target image. Light containing target image information is emitted and incident on the pixelated harmonic diffraction element. The pixelated harmonic diffraction element is generated by discretizing the harmonic diffraction element pixel by pixel, and is composed of a plurality of discrete structural pixels, and the structural pixels are aligned one by one with the image pixels on the color transparent display screen; Each structural pixel on the pixelated harmonic diffraction element diffracts the light emitted by the image pixel on the aligned color transparent display screen in a directionally directed manner to the optical center of the lens of the human eye and ultimately to the retina, thereby forming the effect of retinal projection color near-eye display; The design steps of the pixelated harmonic diffraction element are as follows: S1: Determination of harmonic diffraction conditions: Determine the design main wavelength based on the luminous spectrum of the color transparent display Harmonic diffraction coefficient Then, the harmonic diffraction condition is determined according to the harmonic diffraction achromatic principle, that is, the harmonic diffraction wavelength Harmonious diffraction orders : ； S2: Phase calculation of the harmonic diffraction element: Establish the coordinate system of the display plane and the observation plane, and record the distance between the two planes as , any position on the display plane is recorded as , the position of the optical center of the human eye lens on the observation plane is recorded as , then calculate the phase distribution of the harmonic diffraction element for: ； in, Indicates the remainder operation; S3: Continuous morphology acquisition of harmonic diffraction element: Select the material of the harmonic diffraction element and calculate the refractive index of the material. Calculation of the maximum structural height of a harmonic diffraction element for: ； Thus, the height distribution of the harmonic diffraction element can be obtained for: ； That is the continuous morphology of the harmonic diffraction element; S4: Stepping of harmonic diffraction elements: Establishing a mapping relationship between the number of quantitative steps in the height of the harmonic diffraction element and the diffraction efficiency, and determining the number of steps by comprehensively considering the diffraction efficiency and processing accuracy factors. , and then the height distribution of the harmonic diffraction element Perform quantization processing to obtain the stepped height distribution of the harmonic diffraction element for: ； This is the multi-step morphology of the harmonic diffraction element, where Indicates rounding operation; S5: Discrete pixelation of harmonic diffraction elements: Discrete the designed harmonic diffraction elements according to the pixel size and pixel pitch of the color transparent display screen. Specifically, the color transparent display screen is used as a binary mask. , that is, the element value corresponding to the coordinate within the image pixel area is 1, and the element value corresponding to the coordinate outside the image pixel area is 0. Then, the stepped height distribution of the harmonic diffraction element is used. Multiply by the binary mask The height distribution of the pixelated harmonic diffraction element can be obtained for: ； At this point, the overall design of the pixelated harmonic diffraction element is completed.

2. The augmented reality near-eye display system based on pixelated harmonic diffraction element according to claim 1, characterized in that: The size of the structure pixel is equal to the size of the image pixel on the color transparent display screen, and the spacing between adjacent structure pixels is equal to the spacing between adjacent image pixels on the color transparent display screen.

3. The augmented reality near-eye display system based on pixelated harmonic diffraction element according to claim 1, characterized in that: The light corresponding to the designed main wavelength and the harmonic diffraction wavelength emitted by each image pixel will propagate in the same direction after harmonic diffraction by the aligned structural pixels, thereby achieving an achromatic display effect.

4. The augmented reality near-eye display system based on pixelated harmonic diffraction element according to claim 1, characterized in that: The color transparent display screen and pixelated harmonic diffraction element both have the function of transmitting light emitted by real objects, so that the light emitted by real objects can enter the human eye and eventually reach the retina, thereby realizing the superposition and fusion of the real object image and the image displayed on the color transparent display screen on the retina, forming the effect of augmented reality color near-eye display.

5. The augmented reality near-eye display system based on pixelated harmonic diffraction element according to claim 1, characterized in that: The color transparent display screen is any one of an organic light emitting diode display, a micron-level organic light emitting diode display, a micron-level inorganic light emitting diode display, and a nanometer-level inorganic light emitting diode display.

6. The augmented reality near-eye display system based on pixelated harmonic diffraction element according to claim 1, characterized in that: The material of the pixelated harmonic diffraction element is quartz glass or K9 glass.

7. The augmented reality near-eye display system based on pixelated harmonic diffraction element according to claim 1, characterized in that: The minimum characteristic size of the microstructure on the pixelated harmonic diffraction element is greater than 300 nm.

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