A HUD image generation device based on translational reconstruction metasurface

Abstract

This invention discloses a head-up display (HUD) image generating device based on a translational reconstruction metasurface, belonging to the field of image display. Commonly used pattern information is pre-stored in the metasurface, enabling the transmission of images to the driver using an existing windshield. The image generation unit of this HUD image generating device consists of two metasurfaces. The high transmittance and high diffraction efficiency of the metasurfaces effectively improve light energy utilization, offering advantages such as high lumen output, low cost, and small size. It overcomes the problems of large size, high cost, and limited lumen output in existing head-up display systems, making it suitable for various scenarios and providing a new solution in the field of head-up display technology.

Description

Technical Field

[0001] This invention relates to a HUD image generation device and design method based on a translational reconstruction metasurface, and more specifically, to the fields of micro-nano optics and head-up display technology. Background Technology

[0002] In the field of smart cockpits, HUD (Head-Up Display) systems are systems that project important information such as vehicle speed, fuel consumption, tire pressure, navigation data, and central infotainment information onto a display medium in front of the driver. Thanks to in-vehicle HUDs, drivers do not need to frequently shift their gaze from the road to the instrument panel or central screen, effectively improving driving safety. The PGU (Picture Generation Unit), as the core component of the HUD, not only directly determines the image quality but also significantly affects its productization cost. Currently, the industry-recognized PGU technology paths mainly include four types: TFT-LCD (Thin Film Transistor Liquid Crystal Display), DLP (Digital Light Processing), LBS (Laser Beam Scanning), and LCOS (Liquid Crystal on Silicon). In the cost structure of AR-HUDs, the PGU accounts for the highest value, reaching 30% to 50% of the total BOM (Bill of Materials). However, the large installation size and high cost of HUDs remain common pain points in the industry.

[0003] Based on this, a new solution is to replace the image generation unit (PGU) with a translation reconstruction metasurface, pre-storing commonly used pattern information within the metasurface. The metasurface is composed of a subwavelength array of dielectric nanorods, exhibiting high transmittance, high diffraction efficiency, and strong wavelength selectivity. It can perform high-resolution modulation of the amplitude and phase of the light field. The high diffraction efficiency significantly improves energy utilization efficiency, providing the advantage of high brightness, and its compact size facilitates the integration of HUD systems into different vehicle models. Summary of the Invention

[0004] The purpose of this invention is to provide a HUD image generation device based on a translational reconstruction metasurface. This method utilizes translational reconstruction metasurface holographic projection technology, taking the relative translational position as a new holographic multiplexing dimension, and changing the pattern at the center of the field of view through translation.

[0005] The technical solution of this invention is a HUD image generating device based on translational reconstruction metasurface, which includes: a circuit system, a mechanical drive system, an image generating unit, and an optical emission device;

[0006] The circuit system includes an emission control module and a drive control module. The image generation unit includes metasurface A and metasurface B. The emission control module outputs a control signal to the optical emission device, which outputs a laser to the image generation unit. The emission control module outputs a drive control signal to the drive control module, which outputs a drive signal to the mechanical drive component, which drives the metasurface B to move.

[0007] Metasurface A and metasurface B are light-transmitting materials, each consisting of a substrate and an array of nanorods on the substrate. Metasurface A is fixed, while metasurface B moves through a mechanically driven component. The laser emitted by the optical generator passes through metasurface A and metasurface B in sequence to form an outgoing image, which is then projected onto the front of the windshield after passing through a small hole.

[0008] Furthermore, the substrates of metasurface A and metasurface B are silicon dioxide, and the material of the nanorod array is titanium dioxide.

[0009] Furthermore, the method for determining the nanorod array patterns of metasurface A and metasurface B is as follows:

[0010] Step 1: Based on image P, use the GS algorithm based on the Rayleigh-Sommerfeld formula to obtain the phase distribution of the emitted wave from metasurface B.

[0011] Step 2: Based on the characteristic that the in-plane translational degree of freedom and the beam deflection degree of freedom are the same, and the generalized Snell's law, establish the x-direction translation variable s. x y-direction translation variable s y With beam deflection angle θ, The functional relationship is derived, and the incident wave phase distribution function of metasurface B is also derived.

[0012] Suppose there is a wavefront modulation plane with z = 0 in the xyz coordinate system, hereinafter referred to as plane B; the incident wave phase distribution function of the metasurface B. t1 is a constant, and x and y represent the coordinate system in which plane B lies;

[0013] Step 3: Assign a tilt factor θ to the phase distribution of the emitted wave from metasurface B. Subtracting the incident wave phase distribution from metasurface B yields the phase distribution φ of metasurface B. B The complex amplitude UB of metasurface B is calculated as follows:

[0014]

[0015] in, UB represents the complex amplitude of the outgoing wave from metasurface B obtained from a single image using the GS algorithm based on the Rayleigh-Sommerfeld formula. i Let θ represent the complex amplitude of the incident wave on metasurface B, k0 represent the wave vector of light in vacuum, and θ represent the complex amplitude of the incident wave on metasurface B. p Indicates the angle of elevation. Indicates azimuth, x B y B This represents the plane B coordinate system, and n represents the total number of images to be displayed.

[0016] via s x and s y The changes allow for deflection at any angle within the hemisphere, where the elevation angle θ and azimuth angle are included in the deflection angle. Represented as:

[0017]

[0018] in:

[0019]

[0020] Step 4: After obtaining the incident wave phase distribution function of metasurface B, the phase distribution of metasurface A is calculated using the Rayleigh-Sommerfeld formula.

[0021] Using the Rayleigh-Sommerfeld diffraction formula, To inverse the transmission phase distribution function of the metasurface A on plane A, which is a distance d from plane B, given the initial conditions.

[0022]

[0023] in, This represents the complex amplitude of metasurface A. This represents the complex amplitude of the incident wave on metasurface B. x A ,y A Let d represent the coordinate system on plane A, and let d represent the distance between metasurfaces A and B in the direction of light propagation.

[0024] Step 5: Encode the complex amplitudes obtained in steps 3 and 4 using dielectric nanorods, and calculate the phase distribution of the corresponding metasurface using the following formula.

[0025] Furthermore, the specific method of step 5 is as follows: using dielectric nanorods with high transmittance of co-polarized linear polarization, the side length parameters of the dielectric nanorods at each position in the metasurface are determined according to the spatial phase distribution of the target light field.

[0026] The shape and size of the nanorod antenna are determined by rigorous coupled-wave analysis or finite-difference time-domain method.

[0027] Beneficial effects:

[0028] 1. The present invention discloses a HUD image generation device and design method based on translational reconstruction metasurface, which can endow the translational reconstruction metasurface system with a large information capacity, utilize the relative translational position as a new holographic multiplexing dimension, and switch the pattern in the center of the field of view through translation.

[0029] 2. The HUD image generation device and design method based on translational reconstruction metasurface disclosed in this invention have great potential in the field of head-up display technology. The high diffraction efficiency greatly improves the energy utilization efficiency, has the advantage of high brightness, and compresses the volume, which is conducive to assembling the HUD system into different models of vehicles.

[0030] 3. The present invention discloses a HUD image generation device and design method based on translation reconstruction metasurface. Traffic sign patterns are pre-stored in the metasurface. According to the generalized Snell's law, the relationship between beam deflection angle and translation variable is established. By translating the metasurface B, the pattern in the center of the field of view can be freely switched, thereby improving the information reuse rate. Attached Figure Description

[0031] Figure 1 This is a structural block diagram of the display system provided in Embodiment 1 of the present invention.

[0032] Figure 2 This is a schematic diagram of the display system provided in Embodiment 1 of the present invention;

[0033] Figure 3 This is a schematic diagram of the structure of the image generation unit of the display device provided in Embodiment 1 of the present invention;

[0034] Figure 4 This is a top view of the image generation unit of the display device provided in Embodiment 1 of the present invention;

[0035] Figure 5 This is a side view of the image generation unit of the display device provided in Embodiment 1 of the present invention;

[0036] Figure 6 The relationship between the phase and transmission coefficient and the side length of the nanorod is provided by the direct calculation method in Embodiment 1 of the present invention.

[0037] Figure 7 The phase distribution diagrams of metasurfaces A and B provided in Example 1 of the present invention are shown.

[0038] Figure 8This is a schematic diagram of the image switching function provided in Embodiment 1 of the present invention. Detailed Implementation

[0039] To better illustrate the purpose and advantages of the present invention, the invention will be further described below in conjunction with the accompanying drawings and examples.

[0040] Example 1

[0041] The HUD image generation unit based on translational reconstruction metasurface utilizes the relative translational position as a new holographic multiplexing dimension to switch the pattern in the center of the field of view.

[0042] Figure 1 The structural block diagram of the display system includes: an optical emitting device, an image generating unit, a circuit system, and a mechanical drive system; the optical emitting device includes: a visible light laser, responsible for emitting laser light; the image generating unit includes: two metasurfaces A and B stacked at a preset distance, and metasurface B can move in the XOY plane; the circuit system includes: an emission control module and a drive control module; the mechanical drive system is responsible for mechanically driving the metasurface B of the image generating unit to switch the pattern in the center of the field of view.

[0043] like Figure 2-3 The diagram shows a schematic of the display system and an image generation unit provided in Embodiment 1 of the present invention, including a windshield (1), an image generation unit (2), and a visible light laser (3). The visible light laser (3) emits a laser beam, and the driver in the cockpit can reflect the imaging beam generated by the image generation unit (2) to the driver's eyes through the windshield (1), so that the driver can view the image generated by the image generation unit (2) through the windshield (1).

[0044] In a further embodiment, the image generation unit (2) is formed by stacking metasurface A (4) and metasurface B (5) with a spacing of 200 μm, and metasurface B (5) can move in the XOY plane, and the center wavelength of the visible light laser (3) is 0.488 μm.

[0045] In a further embodiment, according to the design, metasurface A (4) has a size of 450.2 μm × 450.2 μm and contains 2251 × 2251 pixels, and metasurface B (5) has a size of 60.2 μm × 60.2 μm and contains 301 × 301 pixels. Each pixel consists of a single titanium dioxide nanorod, and the substrate of metasurface A and metasurface B is silicon dioxide (13).

[0046] like Figure 4-5 The figures shown are a top view and a side view of the image generation unit of the display device provided in Embodiment 1 of the present invention.

[0047] In a further embodiment, the period q of the nanorods is 0.2 μm, and multiple titanium dioxide nanorods (6), (7), (8), (9), (10), (11), (12) with different side lengths are arranged in a two-dimensional array on a silicon dioxide substrate (13).

[0048] Design Method of HUD Image Generation Device Based on Translation Reconstruction Metasurface

[0049] Step 1: Use the GS (Gerchberg-Saxton) algorithm based on the Rayleigh-Sommerfeld formula to efficiently obtain the phase distribution of the emitted wave from the metasurface B of the image generation unit constituting the image generation device. Ρ∈{1,2,3,4,5,6,7,8,9}, where Ρ represents different pictures;

[0050] Step 2: Based on the characteristic that the in-plane translational degree of freedom and the beam deflection degree of freedom are the same, and the generalized Snell's law, establish the translation variable s. x s y With beam deflection angle θ, The functional relationship is derived, and the incident wave phase distribution function of metasurface B is also derived.

[0051] The incident wave phase distribution function of the metasurface B

[0052] This makes

[0053] Step 3: Assign a tilt factor θ to the phase distribution of the emitted wave from metasurface B. Subtracting the incident wave phase distribution from the metasurface B yields the phase distribution of the metasurface B, and the complex amplitude of the metasurface B is:

[0054]

[0055] This makes

[0056] Step 4: After obtaining the incident wave phase distribution function of metasurface B, the phase distribution of metasurface A can be calculated using the Rayleigh-Sommerfeld formula.

[0057] The specific calculation method for calculating the phase distribution of metasurface A using the Rayleigh-Sommerfeld formula is as follows:

[0058] Using the Rayleigh-Sommerfeld diffraction formula, To invert the transmission phase distribution function of metasurface A, which is at a distance d from metasurface B, based on the initial conditions.

[0059]

[0060] Step 5: Design the dielectric nanorods that make up metasurfaces A and B using rigorous coupled-wave analysis or finite-difference time-domain method.

[0061] Through a series of simulations based on rigorous coupled-wave analysis and finite-difference time-domain method, titanium dioxide nanorods were selected as the basic building blocks of metasurfaces A and B, and the phase distribution of metasurfaces A and B was encoded using the transmission phase modulation principle.

[0062] In the structural design, the height of the titanium dioxide nanorod antenna was fixed at 0.8 μm, the period in the x and y directions was fixed at 0.2 μm, and the operating wavelength was set to 0.488 μm. Under these conditions, the side length of the titanium dioxide nanorod antenna was scanned in steps of 0.0002 μm within a range of 50 μm to 150 μm, with a phase coverage of 0–2π and a transmission coefficient above 0.94. Figure 6 As shown.

[0063] Figure 7 The phase distribution diagrams of metasurfaces A and B provided in Example 1 of the present invention are shown.

[0064] Figure 8 This is a schematic diagram of the image switching function provided in Embodiment 1 of the present invention. When the metasurface B is translated 40μm up, down, left and right along the X and Y axes, the traffic signs "turn left", "go straight", "turn right", "keep left", "make a U-turn", "keep right", "go straight and turn left", "turn left and right", and "go straight and turn right" can be switched to the center of the field of vision in sequence.

[0065] In summary, this embodiment provides a HUD image generation device and design method based on translational reconstruction metasurface. It can utilize the relative translational position as a new multiplexing dimension to freely switch the projection in space to the center of the field of view, and can be applied to the field of head-up display technology.

[0066] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A HUD image generation device based on a translational reconstruction metasurface, the device comprising: Circuit system, mechanical drive system, image generation unit, optical emission device; The circuit system includes an emission control module and a drive control module. The image generation unit includes metasurface A and metasurface B. The emission control module outputs a control signal to the optical emission device, which outputs a laser to the image generation unit. The emission control module outputs a drive control signal to the drive control module, which outputs a drive signal to the mechanical drive component, which drives the metasurface B to move. The metasurfaces A and B are light-transmitting materials, each consisting of a substrate and an array of nanorods on the substrate. Metasurface A is fixed, while metasurface B moves through a mechanically driven component. The laser emitted by the optical generator passes through metasurfaces A and B in sequence to form an outgoing image, which is then projected onto the front of the windshield after passing through a small hole. The method for determining the nanorod array patterns of metasurface A and metasurface B is as follows: Step 1: Based on image P, obtain the phase distribution of the emitted wave from metasurface B using the GS algorithm based on the Rayleigh-Sommerfeld formula. Step 2: Based on the characteristic that the in-plane translational degree of freedom and the beam deflection degree of freedom are the same, and the generalized Snell's law, establish the x-direction translation variable s. x y-direction translation variable s y With beam deflection angle θ, The functional relationship is derived, and the incident wave phase distribution function of metasurface B is also derived. Suppose there is a wavefront modulation plane with z = 0 in the xyz coordinate system, hereinafter referred to as plane B; the incident wave phase distribution function of the metasurface B. t1 is a constant, and x and y represent the coordinate system in which plane B lies; Step 3: Assign a tilt factor θ to the phase distribution of the emitted wave from metasurface B. Subtracting the incident wave phase distribution from metasurface B yields the phase distribution φ of metasurface B. B The complex amplitude UB of metasurface B is calculated as follows: in, UB represents the complex amplitude of the outgoing wave from metasurface B obtained from a single image using the GS algorithm based on the Rayleigh-Sommerfeld formula. i Let θ represent the complex amplitude of the incident wave on metasurface B, k0 represent the wave vector of light in vacuum, and θ represent the complex amplitude of the incident wave on metasurface B. p Indicates the angle of elevation. Indicates azimuth, x B y B This represents the plane B coordinate system, and n represents the total number of images to be displayed. via s x and s y The changes allow for deflection at any angle within the hemisphere; the elevation angle θ and azimuth angle are part of the deflection angle. Represented as: in: Step 4: After obtaining the incident wave phase distribution function of metasurface B, the phase distribution of metasurface A is calculated using the Rayleigh-Sommerfeld formula. Using the Rayleigh-Sommerfeld diffraction formula, To inverse the transmission phase distribution function of the metasurface A on plane A, which is a distance d from plane B, given the initial conditions. in, This represents the complex amplitude of metasurface A. This represents the complex amplitude of the incident wave on metasurface B. x A ,y A Let d represent the coordinate system on plane A, and let d represent the distance between metasurfaces A and B in the direction of light propagation. Step 5: Encode the complex amplitudes obtained in steps 3 and 4 using dielectric nanorods, and calculate the phase distribution of the corresponding metasurface using the following formula.

2. The HUD image generating device based on a translational reconstruction metasurface as described in claim 1, characterized in that, The substrates of metasurfaces A and B are silicon dioxide, and the material of the nanorod array is titanium dioxide.

3. The HUD image generating device based on a translational reconstruction metasurface as described in claim 1, characterized in that, The specific method of step 5 is as follows: using dielectric nanorods with high transmittance of co-polarized linear polarization, the side length parameters of the dielectric nanorods at each position in the metasurface are determined according to the spatial phase distribution of the target light field.

Images