A virtual reality near-eye display optical structure with local beam deflection

Abstract

The present application relates to a kind of local light beam deflection virtual reality near-eye display optical structure.The structure includes micro display panel, optical imaging lens and light beam deflection superstructure surface.The light beam deflection superstructure surface includes substrate layer and nanostructure unit periodically distributed on the substrate layer, which is divided into different regions according to pixel position and designed differently, forming different deflection angles.The present application can realize the independent regulation of deflection angle of each pixel position, with the characteristics of simple design and wide applicability, which can be applied to VR virtual reality display system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of virtual reality, in particular to a virtual reality near-eye display optical structure with local light beam deflection. BACKGROUND

[0002] The super surface is a kind of subwavelength structure, and is a kind of artificial material with special properties that traditional materials cannot realize, such as changing the propagation properties of light and other electromagnetic waves. By using the phase discontinuity to control the wave front of light waves, abnormal reflection and refraction of light waves, and even arbitrary control of light field polarization can be realized.

[0003] Virtual reality (VR) technology is a collection of widely used computer science and simulation technologies, which can compile, transmit and project the digital language stored in the computer so that the user can perceive. Correspondingly, the sensing device of the computer can also recognize and respond to the signals output by the user. In the traditional virtual reality display system, the solid angle corresponding to the pupil is small, only a small part of the display pixel angle spectrum. Therefore, only a small part of the light emitted from the edge pixel is captured by the observer, resulting in a large waste and greatly reducing the light efficiency.

[0004] Therefore, it is necessary to solve the problem of low light efficiency of edge pixels in the existing virtual reality display technology. SUMMARY

[0005] The present application aims to fill the gap in the prior art, and provides a virtual reality near-eye display optical structure with local light beam deflection, that is, a super surface structure and a design method for realizing pixel-by-pixel light beam deflection control in the visible light band. The designed structure can be used in virtual reality near-eye display devices.

[0006] To achieve the above-mentioned purpose, the technical scheme of the present application is: a virtual reality near-eye display optical structure with local light beam deflection, comprising a micro display panel, an optical imaging lens and a light beam deflection super surface; the light beam deflection super surface comprises a substrate layer and a plurality of nano structure units periodically distributed on the substrate layer, and the light beam deflection super surface is divided into different regions according to the pixel position and designed differently. The region division corresponds to the micro display panel pixel one by one, that is, different super surface structures are designed in different regions of the micro display panel, forming different deflection angles. In the virtual reality near-eye display optical structure, the direction of the outgoing light of each pixel is deflected and controlled, and finally the outgoing light normal direction of each pixel is deflected to point to the human eye direction.

[0007] In an embodiment of the present application, the design method of the light beam deflection superstructure surface comprises designing the periodic distribution of the nanostructure unit on the substrate layer, which is limited to the pixel position, i.e. the pixel position is different, and the periodic distribution is also different. The steps of determining the periodic distribution of the light beam deflection superstructure surface are as follows:

[0008] S1, constructing a nanostructure unit, scanning each geometric parameter of the nanostructure unit by using a method comprising a rigorous coupled wave analysis algorithm, obtaining the transmittance and phase distribution of light at a target incident wavelength under different geometric parameters of the nanostructure unit, and establishing a structure library;

[0009] S2, calculating according to the coordinate position of the pixel on the micro display panel to obtain the target angle value of the light beam deflection superstructure surface required to deflect the light;

[0010] S3, after determining the required deflection angle, calculating three target phase distributions under the red light wavelength, green light wavelength and blue light wavelength required by the display according to the custom;

[0011] S4, selecting the nanostructure unit satisfying the three target phase distributions from the structure library established in step S1 according to the target phase distribution of the corresponding wavelength, and arranging the position of the nanostructure unit in the space on the substrate layer to obtain the periodic distribution of the nanostructure unit on the substrate layer.

[0012] In an embodiment of the present application, the micro display panel comprises a planar screen of LCD, Micro-OLED, Micro-LED; the optical imaging lens comprises a lens combination in a spherical lens, an aspherical lens, a Fresnel lens and a Pancake optical scheme, and the thickness of the lens or the lens combination is as small as possible; the incident light comprises a plane wave and a spherical wave.

[0013] In an embodiment of the present application, the material of the substrate layer is a low refractive index transparent medium, including sapphire, K9 glass, fused quartz glass, and low refractive index materials of flexible organic transparent materials.

[0014] In an embodiment of the present application, the gap between the nanostructure units is air or a low refractive index transparent medium, and the nanostructure units are bonded by a high molecular organic matter; the low refractive index transparent medium comprises MgF2, MgO and SiO2, and the high molecular organic matter comprises SU8, PDMS and polyimide, and the thickness is about 0.1-2 μm.

[0015] In an embodiment of the present application, the preparation method of the nanostructure unit comprises femtosecond laser direct writing, electron beam etching, focused ion beam etching, nanoimprint, and micro-nano fabrication technology of interference lithography.

[0016] In an embodiment of the present application, the nanostructure unit is obtained by splicing the sub-nanostructure of each pixel using an array unit phase curve splicing technology or an electromagnetic coupling splicing technology.

[0017] In an embodiment of the present application, in the step S2, a rectangular coordinate system is first established, taking the normal direction of the micro display panel as the optical axis Z axis, and taking the direction perpendicular to the optical axis and the long axis or the short axis of the micro display panel as the Y axis, so that the coordinate position of the pixel on the micro display panel is (0, y screen ), and the required deflection angle is calculated as:

[0018]

[0019] wherein y screen is the longitudinal coordinate of the pixel on the micro display panel, x len and y len are the horizontal and vertical coordinates of the intersection point of the light and the lens, y screen and x len are known quantities, and y len is obtained from the similar triangle formula:

[0020]

[0021] wherein x image and y image are the horizontal and vertical coordinates of the virtual image point, x eye is the horizontal coordinate of the eye position and is a known quantity, and y image is obtained from the formula of the vertical axis magnification:

[0022]

[0023] wherein x image is obtained from the thin lens imaging formula:

[0024]

[0025] wherein f is the equivalent focal length of the optical imaging lens;

[0026] The above parameters are substituted into the formula of θ i to obtain the target angle value of the light beam deflection superstructure surface required to deflect the light.

[0027] In an embodiment of the present application, in the step S3, according to the required deflection angle adjustment effect, it can be known from the generalized Snell's law that:

[0028]

[0029] wherein λ i (i=R, G, B) is the target wavelength, the phase gradient corresponding to the corresponding target wavelength, θ i (i=R, G, B) is the design deflection angle of R, G and B, R represents red light, G represents green light, B represents blue light, and P is the period of the nanostructure unit; considering dense wavefront control, it is set to If the system has more than three primary colors of RGB, the calculation method refers to the above formula.

[0030] In an embodiment of the present application, in step S4, the nanostructure unit that meets the multiple target phase distributions is selected from the structure library, so that the light beam deflection superstructure surface meets the conditions of transmittance greater than 80% and phase coverage of 0-2pi in the entire wavelength range.

[0031] Compared with the prior art, the present application has the following beneficial effects: the present application adds an optical superstructure surface to the traditional virtual reality near-eye display system, and different superstructure surfaces can be designed according to different pixel positions, thereby realizing light beam deflection. The adaptability and reliability are strong, and the present application can be widely applied to various virtual reality use scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic diagram before and after light beam deflection realized in embodiment 1 of the present application.

[0033] Figure 2 is a front view of the nanostructure unit of the superstructure surface in embodiment 1 of the present application.

[0034] Figure 3 is a top view of the nanostructure unit of the superstructure surface in embodiment 1 of the present application.

[0035] Figure 4 is a schematic diagram of the working principle of the superstructure surface in embodiment 1 of the present application.

[0036] Figure 5 is a schematic diagram of the light beam deflection realized by the superstructure surface in embodiment 1 of the present application.

[0037] Figure 6 is a design flowchart of the superstructure surface in embodiment 1 of the present application. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and do not constitute a limitation on the present application.

[0039] The application provides a virtual reality near-eye display optical structure for local light beam deflection, comprising a micro display panel, an optical imaging lens and a light beam deflection superstructure surface; the light beam deflection superstructure surface comprises a substrate layer and nanostructure units periodically distributed on the substrate layer, and the light beam deflection superstructure surface is divided into different regions according to pixel positions and is designed differently, that is, different superstructure surfaces are designed in different regions of the micro display panel to form different deflection angles, so that the direction of the outgoing light of each pixel is deflected and regulated in the virtual reality near-eye display optical structure, and finally the outgoing light normal direction of each pixel is deflected to point to the human eye direction. The design method of the light beam deflection superstructure surface comprises designing the periodic distribution of the nanostructure units on the substrate layer, and the periodic distribution is limited by the pixel position, that is, the pixel position is different, and the periodic distribution is also different, and the steps for determining the periodic distribution of the light beam deflection superstructure surface are as follows:

[0040] S1, constructing a nanostructure unit, scanning each geometric parameter of the nanostructure unit by using a method comprising a rigorous coupled wave analysis algorithm, obtaining the transmittance and phase distribution of light of the nanostructure unit at a target incident wavelength under different geometric parameters, and establishing a structure library;

[0041] S2, calculating according to the coordinate position of the pixel on the micro display panel to obtain a target angle value at which the light beam deflection superstructure surface needs to deflect the light;

[0042] S3, after the required deflection angle is determined, the three target phase distributions under the red light wavelength, the green light wavelength and the blue light wavelength required by display are calculated;

[0043] S4, according to the target phase distribution of the corresponding wavelength, selecting the nanostructure units satisfying the three target phase distributions from the structure library established in step S1, and arranging the positions of the nanostructure units in the space on the substrate layer to obtain the periodic distribution of the nanostructure units on the substrate layer.

[0044] The following is a specific embodiment of the application.

[0045] Embodiment 1

[0046] A superstructure surface that can be used to realize local light beam deflection in a virtual reality near-eye display device, the realized light beam deflection is as shown in Figure 1 , the structure is as shown in Figure 2 and Figure 3 , which are the front view and top view of the nanostructure units of the superstructure surface in embodiment 1. Among them, P x is the period of the nanostructure units along the x-axis direction, P yThe period of the nanostructure unit along the y-axis direction is h, which is the height of the nanostructure unit; as can be seen from the figure, the super-structured surface includes a substrate layer 12 and a plurality of rectangular column nanostructure units 11 arranged periodically on the surface of the substrate layer. This structure increases the geometric parameter freedom degree and expands the phase distribution range at the target wavelength. According to the working waveband, the cylindrical structure selects titanium dioxide material with small absorption and high refractive index in the visible light waveband, and the substrate layer selects silicon dioxide material with low refractive index.

[0047] The multi-layer super-structured surface provided by the application can realize multiplexing of different wavelengths, such as Figure 4 As shown in the figure, it is a working principle schematic diagram of the super-structured surface in Example 1.

[0048] As shown in the figure, it is a working principle schematic diagram of the super-structured surface in Example 1. Figure 5 As shown in the figure, it is a schematic diagram of the super-structured surface realizing beam deflection in Example 1.

[0049] The distribution of each nanostructure unit in the multifunctional super-structured surface provided by the application is determined according to the following steps, so as to realize Figure 4 As shown in the figure, the flow is as shown in the figure, and the specific steps include: Figure 6

[0050] S1, determine the value range of the freedom degree of the nanostructure unit 11 in a single period, set the wavelength of the incident light, and scan each geometric parameter of the nanostructure unit 11 by using a rigorous coupled wave analysis algorithm, to obtain the transmittance and phase distribution of the light of the nanostructure unit 11 in a single period at the target incident wavelength under different geometric parameters, and establish a structure library.

[0051] S2, calculate according to the coordinate position of the pixel on the micro display panel to obtain the target angle value of the light beam deflection super-structured surface required to deflect the light;

[0052]

[0053] Wherein y screen is the longitudinal coordinate of the pixel on the micro display panel, x len , y len are the horizontal and vertical coordinates of the intersection point of the light and the lens. y screen , x len are known quantities. y len From the similar triangle formula:

[0054]

[0055] Wherein x image , y image are the horizontal and vertical coordinates of the virtual image point, x eye is the horizontal coordinate of the eye position and is a known quantity, and y image ​The formula of the vertical magnification is obtained as follows:

[0056]

[0057] wherein x image The formula of the thin lens imaging is obtained as follows:

[0058]

[0059] wherein f is the equivalent focal length of the optical imaging lens.

[0060] The above parameters are substituted into θ i The formula can be obtained as follows to calculate the target angle value of the light beam deflection super-structured surface required to deflect the light.

[0061] S3, after determining the required deflection angle, the three target phase distributions at the red light wavelength, the green light wavelength and the blue light wavelength are calculated according to the display required custom red light wavelength, green light wavelength and blue light wavelength;

[0062]

[0063] wherein λ i (i=R, G, B) is the target wavelength, is the phase gradient corresponding to the target wavelength, θ i (i=R, G, B) is the design deflection angle of R, G and B, R represents red light, G represents green light, B represents blue light, and P is the period of the nano-structured unit. Considering the dense wavefront control, it is generally set to If the system has more than three RGB primary colors, the calculation method can also be referred to as above.

[0064] S4, according to the target phase distribution of the wavelength, the nano-structured units satisfying the three target phase distributions are selected from the structure library established in S1, and the positions of the nano-structured units are arranged in the space on the substrate layer 12, to obtain the periodic distribution of the nano-structured units on the substrate layer 12.

[0065] The above is the preferred embodiment of the present application, any changes made according to the technical solutions of the present application, as long as the generated function does not exceed the scope of the technical solutions of the present application, belongs to the protection scope of the present application.

Claims

1. A virtual reality near-eye display optical structure with local beam deflection, characterized by, The optical structure comprises a micro display panel, an optical imaging lens, and a light beam deflection superstructure surface; the light beam deflection superstructure surface comprises a substrate layer and nanostructure units periodically distributed on the substrate layer, and is divided into different regions according to pixel positions and is designed differently; the region division corresponds to the pixels of the micro display panel one by one, that is, different superstructure surfaces are designed in different regions of the micro display panel to form different deflection angles, the direction of the outgoing light of each pixel is deflected and regulated in the virtual reality near-eye display optical structure, and finally the outgoing light normal direction of each pixel is deflected to point to the human eye direction; the design method of the light beam deflection superstructure surface comprises designing the periodic distribution of the nanostructure units on the substrate layer, and the periodic distribution is limited by the pixel positions, that is, the pixel positions are different, and the periodic distribution is also different; the steps of determining the periodic distribution of the light beam deflection superstructure surface are as follows: S1, constructing a nanostructure unit, scanning each geometric parameter of the nanostructure unit by using a method comprising a rigorous coupled wave analysis algorithm, obtaining the transmittance and phase distribution of light of the nanostructure unit at a target incident wavelength under different geometric parameters, and establishing a structure library; S2, calculating according to the coordinate positions of the pixels on the micro display panel to obtain a target angle value at which the light beam deflection superstructure surface needs to deflect light; S3, after the required deflection angle is determined, the three target phase distributions under the red light wavelength, the green light wavelength and the blue light wavelength required by the display are calculated; S4, according to the target phase distribution of the corresponding wavelength, selecting the nanostructure units satisfying the three target phase distributions from the structure library established in step S1, and arranging the positions of the nanostructure units in the space on the substrate layer to obtain the periodic distribution of the nanostructure units on the substrate layer; In step S2, a rectangular coordinate system is first established, taking the normal direction of the micro display panel as the optical axis Z-axis, and taking the rectangular long axis or short axis direction of the micro display panel as the Y-axis, perpendicular to the optical axis. The coordinate position of the pixel on the micro display panel is (0, y screen ), and the required deflection angle is calculated as: where y screen is the vertical coordinate of a pixel on the microdisplay panel, x len , y len are the horizontal and vertical coordinates of the intersection of the light ray and the lens, y screen , x len are known quantities, and y len is given by the similarity triangle formula: where x image , y image are the horizontal and vertical coordinates of the virtual image point, x eye is the horizontal coordinate of the eye position and y image is a known quantity, and the vertical coordinate of the eye position is given by the formula: where x image From the thin-lens imaging formula, we have: Wherein f is the equivalent focal length of the optical imaging lens; The above parameters are substituted into θ i The calculation formula can obtain the target angle value of the light beam deflection super-holographic surface required for the light deflection.

2. A virtual reality near-eye display optical structure of partial beam deflection according to claim 1, characterized in that, The micro display panel comprises a plane screen of LCD, Micro-OLED, and Micro-LED; the optical imaging lens comprises a combination of spherical lenses, aspherical lenses, Fresnel lenses, and Pancake optical solutions; the incident light comprises plane waves and spherical waves.

3. A virtual reality near-eye display optical structure of partial beam deflection according to claim 1, characterized in that, The material of the substrate layer is a low-refractive transparent medium, and the low-refractive transparent medium comprises sapphire, K9 glass, fused quartz glass, and flexible organic transparent material.

4. A virtual reality near-eye display optical structure of partial beam deflection according to claim 1, characterized in that, The gap between the nanostructure units is air or low-refractive transparent medium, and the nanostructure units are bonded by high-molecular organic matter; the low-refractive transparent medium comprises MgF2, MgO, and SiO2, and the high-molecular organic matter comprises SU8, PDMS, and polyimide, and the thickness is 0.1-2 μm.

5. A virtual reality near-eye display optical structure of partial beam deflection according to claim 1, wherein, The preparation method of the nanostructure units comprises micro-nano fabrication technologies such as femtosecond laser direct writing, electron beam etching, focused ion beam etching, nanoimprinting, and interference lithography.

6. A virtual reality near-eye display optical structure of partial beam deflection according to claim 1, wherein, The nanostructure units are obtained by array unit phase curve splicing technology or electromagnetic coupling splicing technology.

7. A virtual reality near-eye display optical structure of partial beam deflection according to claim 1, wherein, In the step S3, according to the required deflection angle regulation effect, it can be known from the generalized Snell law that: wherein λ i (i = R, G, B) is a phase gradient corresponding to the corresponding target wavelength, θ i (i = R, G, B) is a phase gradient corresponding to the corresponding target wavelength, θ i (i = R, G, B) is a design deflection angle of R, G, and B, R represents red light, G represents green light, B represents blue light, and P is a period of the nanostructure unit; considering dense wavefront control, it is set to If the system has more than three RGB primary colors, the calculation method refers to the above formula.

8. A virtual reality near-eye display optical structure of partial beam deflection according to claim 1, characterized in that, In the step S4, the nanostructure units satisfying the multiple target phase distribution are selected from the structure library, so that the light beam deflection super-structured surface corresponds to the condition that the transmittance is greater than 80% and the phase coverage is 0-2π in the entire wavelength range.

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