2d / 3d switchable stereoscopic display device based on binary nanograting

Abstract

The application relates to a 2D / 3D switchable stereoscopic display device based on a binary nanometer grating, which comprises a polarization-controllable light source, a light collimator, a pixel array light modulator and a binary nanometer grating phase modulation plate; light emitted from the polarization-controllable light source is collimated through the light collimator, the collimated light emitted from the light collimator passes through the pixel array light modulator and enters the binary nanometer grating phase modulation plate; when TM light is turned on and TE light is turned off, the binary nanometer grating does not produce deflection to the TM light, the pixel array light modulator provides a plane image, and 2D display is realized; when TE light is turned on and TM light is turned off, the binary nanometer grating produces light deflection to the TE light, the phase of the TE light is controlled through the period, height and depth-width ratio of the binary nanometer grating, and then the deflection angle and convergence position of the light are controlled, and 3D display is realized. The device has a simple structure, a wide field of view angle of naked-eye 3D display, high brightness and simple and fast switching.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photoelectric display, and in particular to a 2D / 3D switchable stereoscopic display device based on binary nanometer grating. BACKGROUND

[0002] Parallax stereoscopic display is a widely used three-dimensional display technology, which makes the left and right views displayed by the display to be observed by the left and right eyes of the audience respectively, and uses the binocular vision fusion to generate stereoscopic perception. Parallax stereoscopic display is divided into two categories: one category requires special glasses (or other devices) to obtain stereoscopic perception. The other category is naked-eye self-parallax stereoscopic display. Naked-eye display is often considered to be a more promising category of parallax stereoscopic display due to its high degree of freedom. However, naked-eye display has the problem of visual fatigue, which is often considered to be caused by the vergence accommodation conflict. Increasing the number of view points is often considered to be an important method to solve this problem.

[0003] Common 2D / 3D switchable displays use liquid crystal shutters or liquid crystal lenses to achieve view point control. However, the slow response speed of liquid crystal devices has actually made it difficult to adapt to new display devices.

[0004] 3D display based on binary nanometer grating has the advantages of strong integration and good light field control capability, and can well solve the important contradiction of visual fatigue. However, the current 3D stereoscopic display technology based on binary nanometer grating cannot realize the important function of 2D / 3D switchability.

[0005] In view of the above problems, the present application proposes a 2D / 3D switchable stereoscopic display device based on binary nanometer grating according to the sensitivity of binary nanometer grating to the polarization state of incident light. SUMMARY

[0006] The present application aims to provide a 2D / 3D switchable stereoscopic display device based on binary nanometer grating, which has a simple device structure, wide field of view angle, high brightness, and simple and fast switching.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: a 2D / 3D switchable stereoscopic display device based on binary nanometer grating, comprising:

[0008] A polarization controllable light source, including a switchable TE light source and a TM light source;

[0009] A light collimator;

[0010] A pixel array light modulator for adjusting the brightness and color of incident light to provide a 2D display image;

[0011] A binary nanometer grating phase modulation plate is used to regulate the angle of pixel light;

[0012] The light source emitted from the polarization controllable light source is collimated by the light collimator, and the collimated light emitted from the light collimator enters the binary nanometer grating phase modulation plate through the pixel array light modulator; when the TM light is turned on and the TE light is turned off, the binary nanometer grating does not produce deflection to the TM light, the pixel array light modulator provides a plane image, and 2D display is realized; when the TE light is turned on and the TM light is turned off, the binary nanometer grating produces light deflection to the TE light, the phase of the TE light is regulated through the period, height and aspect ratio of the binary nanometer grating, and then the deflection angle and convergence position of the light are regulated, and 3D display is realized; the number of view points of the light field display is determined by the period structure of the binary nanometer grating phase modulation plate.

[0013] Further, in the polarization controllable light source, the TE light is a transverse electric wave, which has a magnetic field component but no electric field component in the propagation direction, and the TM light is a transverse magnetic wave, which has an electric field component but no magnetic field component in the propagation direction, and the two can be freely and quickly switched.

[0014] Further, the light collimator is a prism grating, a micro-nano structure grating light collimator or a super-structured surface light collimator.

[0015] Further, the pixel array light modulator is a transmissive light modulator or a reflective light modulator.

[0016] Further, the deflection angle of each pixel light of the binary nanometer grating is determined by d x sin θ b =m x λ , m=0, ±1, ±2, …, θ b is the deflection angle, d is the period length of the binary nanometer grating, m is the diffraction order, and λ is the wavelength of the light; the binary nanometer grating in each period length includes n sub-periods, n is a natural number not equal to 0, the length of each sub-period is d / n, the sub-period grating duty cycle is a, and 0.1≤a≤0.9; the diffraction efficiency is regulated by regulating the material refractive index, grating height, grating width and sub-period grating duty cycle of the binary nanometer grating.

[0017] Further, the material of the binary nanometer grating is a transparent dielectric material, and the refractive index is 1.2-3.8; the aspect ratio is smaller by changing the refractive index of the dielectric material.

[0018] Further, in the binary nanometer grating, grating directions are arranged according to light converging directions, when TE light is incident, the electric field component direction is perpendicular to the grating direction, the grating structure parameters are adjusted, the angle of a certain diffraction order is just equal to the required deflection angle of the pixel light, and the light diffraction efficiency of the diffraction order is maximum, so that 3D display is realized; when TM light is incident, the electric field component direction is parallel to the grating direction, and the 0-order light diffraction efficiency of 0-degree deflection angle is maximum, so that 2D display is realized.

[0019] Further, the binary nanometer grating phase modulation plate is placed above the pixel array light modulator, a single pixel point of the pixel array light modulator corresponds to a different period binary nanometer grating diffraction unit, the main diffraction order efficiency is 20%-80%, the light deflection angle is 0-60°, and the naked eye 3D display visual angle range is 0-120°.

[0020] Compared with the prior art, the present application has the following beneficial effects: compared with the traditional 2D / 3D switchable device, the present application introduces a binary blazed binary nanometer grating, the main diffraction order has high efficiency and large angle adjustability, and can realize the naked eye 3D display effect with large angle and high brightness. And only by switching the polarization state, the 2D and 3D display can be quickly switched, which is simple and fast. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a structure schematic diagram of the 2D / 3D switchable stereoscopic display device based on the binary nanometer grating of the embodiment of the present application.

[0022] Figure 2 It is a structure schematic diagram of the polarization controllable light source in the embodiment of the present application.

[0023] Figure 3 It is a structure schematic diagram of the five-period binary nanometer grating in the embodiment of the present application.

[0024] Figure 4 It is a simulation result diagram of the influence of grating height on diffraction efficiency in the embodiment of the present application.

[0025] Figure 5 It is a simulation result diagram of the influence of grating material on grating height selection and diffraction efficiency in the embodiment of the present application.

[0026] Figure 6 It is a diffraction effect diagram of the binary nanometer grating under different polarization states in the embodiment of the present application.

[0027] Figure 7 It is a different deflection effect diagram of different polarization state light after being modulated by the binary nanometer grating in the embodiment of the present application.

[0028] Figure 8A 3D display principle diagram under four-viewpoint conditions in an embodiment of the present application.

[0029] Figure 9 A 2D display principle diagram under four-viewpoint conditions in an embodiment of the present application.

[0030] Figure 10 A horizontal and vertical multi-viewpoint diagram under 3D display effect in an embodiment of the present application.

[0031] Figure 11 A vertical sectional view of a 2D / 3D switchable stereoscopic display device based on binary nanometer grating in an embodiment of the present application. DETAILED DESCRIPTION

[0032] The present application will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] It should be noted that the following detailed description is merely exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0034] It is also to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0035] As Figure 1As shown, this embodiment provides a 2D / 3D switchable stereoscopic display device based on a binary nanograting. The device includes at least a polarization-controllable light source 100, a light collimator 101, a pixel array light modulator 102, and a binary nanograting phase modulation plate 103. The polarization-controllable light source 100 includes switchable TE and TM light sources. Polarized light emitted from the polarization-controllable light source 100 is collimated by the light collimator 101. The collimated light emitted from the light collimator is then passed through the pixel array light modulator 102. The brightness and color of the emitted light are adjusted relative to the incident light. The incident light modulator 102 provides a planar view. The binary nanograting phase modulation plate 103 produces different deflection effects for light with different polarization states. When the TM light is on and the TE light is off, i.e., when the incident light is TM light, the binary nanograting does not deflect the TM light, and the pixel array light modulator 102 provides a planar image, achieving 2D display. When the TE light is on and the TM light is off, i.e., when the incident light is TE light, the binary nanograting deflects the TE light, and the pixel array light modulator 102 provides multiple parallax images. By controlling the phase of the TE light rays through the period, height, and aspect ratio of the binary nanograting, the deflection angle and convergence position of the light rays are controlled, thereby achieving 3D display. The number of viewpoints in the light field display is determined by the periodic structure of the binary nanograting phase modulation plate.

[0036] In the polarization-controllable light source 100, TE light is a transverse electric wave with a magnetic field component but no electric field component in the propagation direction, while TM light is a transverse magnetic wave with an electric field component but no magnetic field component in the propagation direction. The two can be switched freely and quickly. Figure 2 This is one structure of the polarization-controllable light source described in this embodiment. For example... Figure 2 As shown, the polarization-controllable light source consists of the following modules: a light-emitting diode (LED) 1001, an artificial polarizer 1002, and a backlight panel 1003. The LED 1001 provides an unpolarized light source for illuminating the passive light-emitting display device. The artificial polarizer 1002 converts incident natural light into linearly polarized light, and the rotation angle of the artificial polarizer can be adjusted to change the polarization direction of the linearly polarized light, thus achieving the emission of TE and TM light respectively. Generally, for two mutually perpendicular linearly polarized lights, the polarization state can be converted simply by rotating the artificial polarizer by 90°. The backlight panel 1003 and dimming dots 10031 are used to convert the emitted light from the LED 1001, after being polarized by the artificial polarizer, into uniformly emitted polarized light.

[0037] A light collimator collimates incident light. Prism gratings, micro / nano structure grating light collimators, and metasurface light collimators can all achieve the collimation function. Prism gratings have a simple structure, while micro / nano structure grating collimators and metasurface light collimators have the unique advantage of being easy to integrate and realizing ultra-thin display devices.

[0038] The pixel array light modulator comprises a display panel, a driving circuit, a control system and the like. The pixel array light modulator comprises a plurality of unit pixels, the unit pixels are uniformly distributed on the pixel array light modulator, and each unit pixel comprises a plurality of sub-pixels, and the light rays passing through the display panel carry image information. The pixel array light modulator can be a transmissive light modulator or a reflective light modulator

[0039] The binary nanometer grating phase modulation plate 103 is located above the pixel array light modulator 102, and the light rays emitted from the modulator pass through the binary nanometer grating phase modulation plate 103, are converged to a specific view point or directly emitted, so that 2D and 3D different visual effects can be realized.

[0040] The binary nanometer grating is a phase grating type capable of separating the central maximum diffracted by a single grooved surface and the zero-order main maximum of interference between grooved surfaces. Due to its zero-order light splitting and easy-to-meet step shortage characteristics, the diffraction efficiency is very high; according to the calculation of the binary optical element theory, when the number of steps in one period of the grating is 8, the diffraction efficiency can reach 95% in the +1 order of diffraction.

[0041] The structural parameters of the binary nanometer grating include a period length (d), a sub-period length, a grating height, a grating width and a refractive index of a grating material, which are determined by the deflection angle of each pixel light ray required by 3D display.

[0042] In order to further illustrate the binary nanometer grating, taking a five-period binary nanometer grating as an example, the structure thereof is shown in Figure 3 Figure Three Two five-period binary nanometer gratings 1021, the left side of the binary three-period binary nanometer grating model, for the left single five-period binary nanometer grating 1021, the single nanometer column represents its tangent plane, and in an ideal case, the length thereof is infinite, and the width and height are design sizes. For the single five-period binary nanometer grating, 1 in the figure is the 0th sub-period, the length thereof is d*(1 / 5); 2 is the first sub-period, the length thereof is d*(1 / 5); 3 is the second sub-period, the length thereof is d*(1 / 5); 4 is the third sub-period, the length thereof is d*(1 / 5); and 5 is the fourth sub-period, the length thereof is d*(1 / 5). The width of the grating needs to be calculated through the duty cycle thereof in the sub-period; and the formula is as follows:

[0043]

[0044] Wherein m is the corresponding sub-period number (from 0 to M-1), M is the number of sub-periods, and n is the refractive index of the grating medium.

[0045] ​For the medium material selection of silicon dioxide (refractive index is 1.5) five period binary nanometer grating, the grating duty cycle is 0 in the 0th sub-period, the grating duty cycle is 0.2125 in the first sub-period, the grating duty cycle is 0.4499 in the second sub-period, the grating duty cycle is 0.71225 in the third sub-period, and the grating duty cycle is 1 in the fourth sub-period.

[0046] Obviously, for any one binary M period binary nanometer grating, the period length is d, after the medium material is fixed, the duty cycle f of each grating in the sub-period is unchanged under the condition that the period number M is unchanged, so for any one binary M period binary nanometer grating, the duty cycle f of the grating in the sub-period is unchanged. (m) (m) After confirmation, the width of any one grating can be obtained as f (m) *d*(1 / M).

[0047] Under the condition that the incident wavelength is constant, the blazed angle of the binary nanometer grating is determined by the period of the binary nanometer grating. The blazed angle is according to the grating equation of the main maximum of multi-slit interference:

[0048] d×sin θ b =m× λ , m=0 ±1, ±2…

[0049] Where θb is the mth order diffraction angle, d is the period, m is the diffraction order, and λ is the incident light wavelength.

[0050] Taking a five-period binary nanometer grating as an example, under the deviation angle of 0~10°, the large period is 28.649um when the deviation angle is 1°; the large period is 14.327um when the deviation angle is 2°; the large period is 9.554um when the deviation angle is 3°; the large period is 7.168um when the deviation angle is 4°; the large period is 5.740um when the deviation angle is 5°; the large period is 4.7834um when the deviation angle is 6°; the large period is 4.1028um when the deviation angle is 7°; the large period is 3.5926um when the deviation angle is 8°; the large period is 3.196um when the deviation angle is 9°; the large period is 2.879um when the deviation angle is 10°. Different deviation angles correspond to different large periods, and the length of the sub-period is also determined. Different period binary nanometer grating structures can be set at different positions to make the light deviate towards the corresponding position and converge to form a view point.

[0051] After the length of the large period and the sub-period is determined, the height H of the binary nanometer grating can be adjusted through simulation to obtain a higher blazed angle diffraction efficiency. For a five-period binary nanometer grating under the condition of 10° modulation, the simulation result of the grating height H is as follows​Figure 4 As shown, it can be observed that, after determining the periodic parameter, the effect of the grating height on the diffraction efficiency at the blaze angle is periodic, with the highest diffraction efficiency reaching over 50%. The grating height H that achieves the highest diffraction efficiency at the blaze angle can be determined using simulation software.

[0052] In fact, as can be seen from the previously mentioned duty cycle of the binary nanograting sub-period, the refractive index of the medium does have a certain influence on the duty cycle of the binary nanograting sub-period. At the same time, the refractive index of the medium also affects the grating height and diffraction efficiency, as shown in the simulation results. Figure 5 As shown, 1024 represents the effect of the medium's refractive index on the height of the binary nanograting under the highest efficiency condition. It can be seen that as the medium's refractive index increases, the height of the binary nanograting decreases under the highest efficiency condition. 1025 represents the effect of the medium's refractive index on the highest diffraction rate. Obviously, for the medium's refractive index in the range of 1.5 to 2, the proposed binary nanograting achieves a maximum diffraction efficiency of about 50%, which meets the expected target.

[0053] To achieve 2D / 3D switchable light field display, this paper proposes a binary nanograting that exhibits different modulation effects on TE and TM light, with different diffraction efficiencies such as... Figure 6 As shown, for TE1023 incident light, the well-designed binary nanograting can achieve the desired blaze angle exit, while the efficiency of other diffraction orders is very low. For TM1022 incident light, however, it can be observed that this structure has no modulation effect on the light; the highest diffraction order is 0, meaning it propagates along the incident direction, while the efficiency of other diffraction orders is very low. It is precisely this sensitivity to polarized light, along with the excellent diffraction effect of the binary nanograting itself, that allows it to be applied to 2D and 3D switchable displays.

[0054] It must be noted that for the proposed binary nanograting, the polarization direction of the polarized light and the direction of the grating slits are subject to strict requirements, such as... Figure 7 As shown, under TE light incident conditions, the electric field direction of the binary nanograting is strictly parallel to the grating slit direction, and the blaze angle is... Figure 7 On the plane shown, under TM light incident conditions, the electric field direction of the binary nanograting is strictly perpendicular to the grating slit direction, while the exit direction remains unchanged. Therefore, it is essential to ensure that the geometric relationship between the electric field and the slit is perpendicular or parallel; that is, the orientation of the grating arrangement in the binary nanograting array is fixed. This reduces the difficulty of grating fabrication and arrangement. After determining the dielectric material and the number of sub-periods, it is only necessary to change the period of the grating array, the corresponding grating width, and the height to achieve a wide range of efficient angle modulation in the direction, resulting in a wide-viewing-angle 3D display effect.

[0055] The structure of the binary nanometer grating phase modulation plate corresponds to the structure of the pixel array light modulator, that is, each sub-pixel of the pixel array light modulator has a corresponding binary nanometer grating structure in the binary nanometer grating phase modulation plate. Different positions of the sub-pixels can be flexibly adjusted by adjusting the period, height and other parameter conditions of the binary nanometer grating to adjust the light, so that the sub-pixels at different positions converge to the designed view point under the condition that the incident light is TE light.

[0056] In order to more clearly show the working principle of the proposed 2D, 3D switchable light field display under 3D display, a four-viewpoint 3D light field display is taken as an example for illustration, as shown in Figure 8 As shown in the figure, A1, A2, A3, A4, B1, B2, B3, B4, C1, C2, C3, C4, D1, D2, D3, D4 sixteen small squares are arranged horizontally, A1, B1, C1, D1 are a unit pixel, and so on. There are a total of 4 unit pixels 1022 in the figure, and each unit pixel has 4 sub-pixels. The sixteen pixels are taken as an example to illustrate how naked eye 3D is achieved. It can be seen that each phase modulation plate unit pixel contains 4 sub-pixels, and each phase modulation plate sub-pixel corresponds to a sub-pixel of the pixel array light modulator. Under the condition of TE light incidence, it can be seen that the light incident to the upper left corner sub-pixel unit A1, A2, A3, A4 of each unit pixel converges to the same designed view point, and B1, B2, B3, B4 also converges to another view point, C1, C2, C3, C4 converges to a third view point, and D1, D2, D3, D4 converges to a fourth view point. When naked eye 3D display is performed, the images output to each view point after passing through the pixel array light modulator are different, so that parallax is formed, giving a three-dimensional display effect. It can be found that for the same position sub-pixels of each unit pixel, the spatial angle of deflection is different with the change of position, so that different periods of each sub-pixel of each binary nanometer grating phase modulation plate are designed to realize different deflection effects.

[0057] Similarly, the working principle under 2D display needs to be explained, and the specific case is as shown in Figure 9As shown, the figure contains sixteen small squares A1, A2, A3, A4, B1, B2, B3, B4, C1, C2, C3, C4, D1, D2, D3, D4, A1, B1, C1, D1 is a body pixel, and so on, and the figure has a total of four body pixels 1022, each body pixel has four sub-pixels, and sixteen pixels are taken as an example to illustrate how 2D display is achieved. It can be seen that each phase modulation version body pixel contains four sub-pixels, and each phase modulation plate sub-pixel and the sub-pixel of the pixel array light modulator are one-to-one corresponding. Under the TM light incidence condition, it can be seen that the light incident to the first pixel unit A1, A2, A3, A4 of each body pixel does not produce converging effect, and B1, B2, B3, B4 also does not produce converging effect, C1, C2, C3, C4 does not produce converging effect, and D1, D2, D3, D4 also keeps collimated light emission. When 2D display is achieved, the output after the pixel array light modulator is a planar view, and the binary nanometer grating phase modulator does not modulate the TM light, the light is collimated and emitted, and the information obtained by the human eyes is the same, that is, 2D display is achieved.

[0058] For the 2D, 3D switchable stereoscopic display device proposed in the present application, super multi-view multi-direction 3D display can be achieved, such as Figure 10 As shown, the number of view points in the horizontal direction is set to 4, and if there are n rows of pixels in the vertical direction, the total number of view points is 4*n, and so on, if the number of view points in the horizontal direction is a, the total number of view points is a*n.

[0059] The present application provides preferred embodiments, but should not be considered to be limited to the embodiments set forth herein. In the figures, the thickness of the layers and regions is enlarged for clarity, but should not be considered to strictly reflect the proportional relationship of the geometric dimensions as a schematic diagram.

[0060] The following is a specific embodiment of the present application:

[0061] Embodiment one

[0062] In this embodiment, the polarization switchable light source 100 is based on a side-in light guide plate structure, the light collimator 101 is a super surface light collimator, the pixel array light modulator 102 is selected to be a transmission type, and the binary nanometer grating phase modulation plate 103 is selected to be a five-period binary nanometer grating array based on fluorophosphor glass medium material (refractive index 1.43).

[0063] Reference Figure 11 A 2D / 3D switchable stereoscopic display device based on a binary nanometer grating, the specific structure is as follows:

[0064] The polarization switchable light source 100 is based on a side-in light guide plate structure, and the TE light source 10011 and the TM light source 10010 are respectively arranged on the left and right sides of the light guide plate 1003, and the light guide plate bottom is a light adjusting dot 10031.

[0065] The polarization switchable light source 100 is based on a side-in light guide plate structure, and the TE light source 10011 and the TM light source 10010 are respectively arranged on the left and right sides of the light guide plate 1003, and the light guide plate bottom is a light adjusting dot 10031.

[0066] The polarization switchable light source 100 is based on a side-in light guide plate structure, and the TE light source 10011 and the TM light source 10010 are respectively arranged on the left and right sides of the light guide plate 1003, and the light guide plate bottom is a light adjusting dot 10031.

[0067] The polarization switchable light source 100 is based on a side-in light guide plate structure, and the TE light source 10011 and the TM light source 10010 are respectively arranged on the left and right sides of the light guide plate 1003, and the light guide plate bottom is a light adjusting dot 10031.

[0068] The polarization switchable light source 100 is based on a side-in light guide plate structure, and the TE light source 10011 and the TM light source 10010 are respectively arranged on the left and right sides of the light guide plate 1003, and the light guide plate bottom is a light adjusting dot 10031.

[0069] For the five-period binary nanometer grating array, if modulation is to be performed in the range of 1°~ 60°, the large period corresponding to the blaze is 28.649um at 1°, and the large period is 0.585um at 60°. The modulation points corresponding to different positions have a large period between 0.585um and 28.649um, which can be calculated according to the grating equation of multi-slit interference maximum.

[0070] For the five-period binary nanometer grating array, the second sub-period duty ratio is 0.0425, the third sub-period duty ratio is 0.08998, the fourth sub-period duty ratio is 0.14248, and the fifth sub-period duty ratio is 0.2000.

[0071] For the five-period binary nanometer grating array, the height is 1.64um at a modulation angle of 1°, and the height is 0.3um at a modulation angle of 60°. The height decreases as the modulation angle increases.

[0072] Example two

[0073] In this embodiment, the polarization switchable light source 100 is based on a side-in light guide plate structure, the light collimator 101 is a micro-nano surface light collimator, the pixel array light modulator 102 is a transmission type, and the binary nanometer grating phase modulation board 103 is a four-period binary nanometer grating array based on a crown glass K6 medium material (refractive index 1.5).

[0074] Reference Figure 11 A 2D / 3D switchable stereoscopic display device based on a binary nanometer grating, the specific structure is as follows:

[0075] The polarization switchable light source 100 is based on a side-in light guide plate structure, and the TE light source 10011 and the TM light source 10010 are respectively arranged on the left and right sides of the light guide plate 1003, and the light guide plate bottom is a light adjusting dot 10031.

[0076] The polarization switchable light source 100 is placed above the micro-nano surface light collimator 101, and there is a certain interval between the super-structure surface light collimator 101 and the polarization switchable light source 100.

[0077] The micro-nano surface light collimator 101 is placed above the transmission type pixel array light modulator 102. The pixel array light modulator 102 and the micro-nano surface light collimator 101 are integrated into one device.

[0078] The binary nano-grating phase modulation plate is arranged above the pixel array light modulator 102. The binary nano-grating is a four-period binary nano-grating array based on fluorophosphor glass medium material (refractive index 1.5).

[0079] The four-period binary nano-grating array has the following parameters:

[0080] For the four-period binary nano-grating array, if modulation is to be performed in the range of 1°-60°, the blaze corresponds to a large period of 28um at 1°, and the blaze corresponds to a large period of 0.564um at 60°. The modulation points corresponding to different positions have a large period between 0.585um and 28.649um, which can be calculated according to the grating equation of the main maximum of multi-slit interference.

[0081] For the above four-period binary nano-grating array, the second sub-period duty cycle is 0.0722, the third sub-period duty cycle is 0.1556, and the fourth sub-period duty cycle is 0.2500.

[0082] For the above four-period binary nano-grating array, the height is 1.5um at a modulation angle of 1°, and the height is 0.3um at a modulation angle of 60°. The height decreases as the modulation angle increases.

[0083] Example Three

[0084] In this embodiment, the polarization switchable light source 100 is based on a side-in light guide plate structure, the light collimator 101 is a super-structure surface light collimator, the pixel array light modulator 102 is a transmission type, and the binary nano-grating phase modulation plate 103 is a binary three-period binary nano-grating array based on a heavy crown glass ZK6 medium material (refractive index 1.61).

[0085] Reference Figure 11 A 2D / 3D switchable stereoscopic display device based on a binary nano-grating has the following specific structure

[0086] The polarization switchable light source 100 is based on a side-entry light guide plate structure. On the left and right sides of the light guide plate 1003 are the TE light source 10011 and the TM light source 10010, respectively, and the bottom of the light guide plate has dimming dots 10031.

[0087] A metasurface collimator 101 is placed above the polarization switchable light source 100, and there is a certain gap between the metasurface collimator 101 and the polarization switchable light source 100.

[0088] A transmissive pixel array light modulator 102 is placed above the metasurface light collimator 101. The pixel array light modulator 102 and the metasurface light collimator 101 are integrated devices.

[0089] Above the pixel array light modulator 102 is a binary nanograting phase modulation plate. The binary nanograting is a four-period binary nanograting array based on the heavy crown glass ZK6 dielectric material (refractive index 1.61).

[0090] Parameters of a binary three-period binary nanograting array:

[0091] For a five-period binary nanograting array, if modulation is desired within the range of 1° to 60°, a large period of 26.8 μm is obtained at 1°, and a large period of 0.5469 μm is obtained at 60°. The large period for each modulation point is between 0.5469 and 26.8 μm, which can be calculated based on the grating equation of the principal maxima of multi-slit interference.

[0092] For the aforementioned five-period binary nanograting array, the duty cycle of the second sub-period is 0.1466, and the duty cycle of the third sub-period is 0.3333.

[0093] For the aforementioned five-period binary nanograting array, the height is 26.8 μm when the modulation angle is 1° and 0.65 μm when the modulation angle is 60°. The height decreases as the modulation angle increases.

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A 2D / 3D switchable stereoscopic display device based on a binary nanograting, characterized in that, include: Polarization-controllable light sources, including switchable TE light sources and TM light sources; Light collimator; A pixel array light modulator is used to adjust the brightness and color of incident light to provide a 2D display image; A binary nanograting phase modulation plate is used to control the angle of pixel light rays; The light emitted from the polarization-controllable light source is collimated by a light collimator. The collimated light then passes through a pixel array light modulator and enters a binary nanograting phase modulation plate. When the TM light is on and the TE light is off, the binary nanograting does not deflect the TM light, and the pixel array light modulator provides a planar image, achieving 2D display. When the TE light is on and the TM light is off, the binary nanograting deflects the TE light. By adjusting the period, height, and aspect ratio of the binary nanograting, the phase of the TE light is controlled, thereby controlling the deflection angle and convergence position of the light, achieving 3D display. The number of viewpoints in the light field display is determined by the periodic structure of the binary nanograting phase modulation plate. In the polarization controllable light source, TE light is a transverse electric wave with a magnetic field component but no electric field component in the propagation direction, while TM light is a transverse magnetic wave with an electric field component but no magnetic field component in the propagation direction. The two can be switched freely and quickly. The light collimator is a prism grating, a micro / nano structure grating light collimator, or a metasurface light collimator; The pixel array optical modulator is a transmissive optical modulator or a reflective optical modulator. The deflection angle of each pixel light in the binary nanograting is determined by d×sinθ. b =m×λ, where m = 0, ±1, ±2... determines θ b Let d be the deflection angle, m be the diffraction order, and λ be the wavelength of the light. Each period of the binary nanograting includes n sub-periods, where n is a natural number not equal to 0. The length of each sub-period is d / n, and the duty cycle of the sub-period grating is a, where 0.1≤a≤0.

9. The diffraction efficiency can be controlled by adjusting the refractive index of the binary nanograting material, the grating height, the grating width, and the duty cycle of the sub-period grating. The binary nanograting material is a transparent medium material with a refractive index of 1.2 to 3.

8. A smaller aspect ratio can be obtained by changing the refractive index of the medium material. In the binary nanograting, the grating direction is arranged according to the light convergence direction. When TE light is incident, the electric field component direction is perpendicular to the grating direction. By adjusting the grating structure parameters, the angle of a certain diffraction order is exactly equal to the required deflection angle of the pixel light, and the light diffraction efficiency of that diffraction order is maximized, thus realizing 3D display. When TM light is incident, the electric field component direction is parallel to the grating direction, and the 0th order light with a 0-degree deflection angle has the maximum diffraction efficiency, thus realizing 2D display. A binary nanograting phase modulation plate is placed above the pixel array light modulator. Each pixel of the pixel array light modulator corresponds to a binary nanograting diffraction unit with a different period. The efficiency of the main diffraction order is 20%-80%, the light deflection angle is 0-60°, and the viewing angle range of naked-eye 3D display is 0-120°.

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