HUD image generation device based on translation reconstruction metasurface

Abstract

The invention discloses an HUD image generation device based on a translation reconstruction metasurface, and belongs to the field of image display. Common pattern information is pre-stored in the metasurface, and an existing windshield can be utilized to transmit an image to a driver. The image generation unit of the HUD image generation device is composed of the two metasurfaces, the high transmittance and the high diffraction efficiency of the metasurfaces effectively improve the light energy utilization rate, and the HUD image generation device has the advantages of being high in lumen, low in cost, small in size and the like. The problems that an existing head-up display system is large in size, high in cost and limited in lumen are solved, the head-up display system is suitable for various scenes, and a new solution is brought to the technical field of head-up display.

Description

Technical Field

[0001] The present invention relates to a HUD image generating device based on a translation reconstruction metasurface and a design method, and more specifically, to the fields of micro-nano optics and head-up display technology. Background Art

[0002] In the field of smart cockpits, the HUD head-up display system is a system that can project important information such as vehicle speed, fuel consumption, tire pressure, navigation data, and central control entertainment information onto a display medium in front of the driver. Thanks to the on-board HUD, the driver does not need to frequently shift his sight from the road to the instrument or central control screen, which effectively improves driving safety. As the core component of HUD, PGU (Picture Generation Unit) not only directly determines the imaging quality of HUD, but also significantly affects its productization cost. At present, the industry-recognized PGU technology paths mainly include four types: TFT-LCD (thin-film transistor liquid crystal display), DLP (digital light processing), LBS laser scanning (Laser Beam Scanning) and LCOS (silicon-based liquid crystal). In the cost structure of AR-HUD, PGU has the highest value share, which can reach 30% to 50% of the whole machine BOM. However, the large installation volume and high cost of HUD are still the pain points commonly faced by the industry.

[0003] Based on this, a new solution is to replace the image generation unit PGU with a translation reconstruction metasurface, and pre-store the commonly used pattern information in the metasurface. The metasurface is composed of a sub-wavelength-sized dielectric nanorod array, which has 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 greatly improves the energy utilization efficiency, has the advantage of high brightness, and has a compressed volume, which is conducive to assembling the HUD system into different models of vehicles. Summary of the invention

[0004] The purpose of the present invention is to provide a HUD image generation device based on a translation reconstruction metasurface. The method can use the relative translation position as a new holographic multiplexing dimension based on the translation reconstruction metasurface holographic projection technology to change the pattern in the center of the field of view by translation.

[0005] The technical solution of the present invention is a HUD image generating device based on a translational reconstruction metasurface, the device comprising: a circuit system, a mechanical drive system, an image generating unit, and an optical emitting device;

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

[0007] The metasurface A and metasurface B are light-transmitting materials, both of which include a substrate and a nanorod array located on the substrate; metasurface A is fixed, and metasurface B moves through a mechanical driving component, and the laser emitted by the optical generating device passes through metasurface A and metasurface B in turn to form an output image, and the formed image is projected in front of the windshield after passing through a small hole.

[0008] Furthermore, the substrates of the supersurface A and the supersurface 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 the supersurface A and the supersurface B is:

[0010] Step 1: According to the image P, the GS algorithm based on the Rayleigh-Sommerfeld formula is used to obtain the phase distribution of the outgoing wave of the metasurface B.

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

[0012] Assume that 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 is t 1 is a constant, x, y represent the coordinate system where plane B is located;

[0013] Step 3: Give the output wave phase distribution of the metasurface B a tilt factor θ, Subtract the incident wave phase distribution of metasurface B to obtain the phase distribution of metasurface B φ B , calculate the complex amplitude UB of the metasurface B as:

[0014]

[0015] in, represents the complex amplitude of the outgoing wave of the metasurface B obtained by the GS algorithm based on the Rayleigh-Sommerfeld formula for a single image, UB i represents the complex amplitude of the incident wave on metasurface B, k 0 represents the wave vector of light in vacuum, θ p represents the elevation angle, represents the azimuth, x B ,y B represents the plane B coordinate system, and n represents the total number of images to be displayed;

[0016] By s x and y The change of can realize any angle deflection in the hemisphere, and the elevation angle θ and azimuth angle in the deflection angle It is expressed as:

[0017]

[0018] in:

[0019]

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

[0021] Using the Rayleigh-Sommerfeld diffraction formula, The transmission phase distribution function of metasurface A on plane A with a distance d from plane B is inverted for the initial condition.

[0022]

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

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

[0025] Furthermore, the specific method of step 5 is: using dielectric nanorods with high co-polarization linear polarization transmittance, and determining the side length parameters of the dielectric nanorods at various positions in the metasurface 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 time domain finite difference method.

[0027] Beneficial effects:

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

[0029] 2. The present invention discloses a HUD image generating device and design method based on a translational reconstruction metasurface, which has 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 has a compressed volume, which is conducive to assembling the HUD system into different models of vehicles.

[0030] 3. The present invention discloses a HUD image generating device and design method based on a translational reconstruction metasurface, which pre-stores traffic sign patterns in the metasurface and establishes a relationship between the beam deflection angle and the translation variable based on the generalized Snell's law. 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A structural block diagram of a display system provided in Example 1 of the present invention

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

[0033] Figure 3 A schematic diagram of the structure of an image generating unit of a display device provided in Embodiment 1 of the present invention;

[0034] Figure 4 A top view of an image generating unit of a display device provided in Embodiment 1 of the present invention;

[0035] Figure 5 A side view of an image generating unit of a 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 provided by the direct calculation method of Example 1 of the present invention;

[0037] Figure 7 Phase distribution diagram of metasurfaces A and B provided in Example 1 of the present invention.

[0038] Figure 8This is a schematic diagram of the image switching function provided by Embodiment 1 of the present invention. DETAILED DESCRIPTION

[0039] In order to better illustrate the purpose and advantages of the present invention, the invention is further described below with reference to the accompanying drawings and examples.

[0040] Example 1

[0041] The HUD image generation unit based on the translational reconstruction metasurface uses the relative translation 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 driving system; the optical emitting device includes: a visible light laser, which is responsible for emitting the laser; the image generating unit includes: two metasurfaces A and B stacked at a preset distance, and the metasurface B can move in the XOY plane; the circuit system includes: an emission control module and a driving control module; the mechanical driving 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 figure shows a schematic diagram of the structure of the display system and the image generation unit provided in Example 1 of the present invention, comprising a windshield (1), an image generation unit (2), and a visible light laser (3). The visible light laser (3) emits a beam of laser light, 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 see the image generated by the image generation unit (2) through the windshield (1).

[0044] In a further embodiment, the image generating unit (2) is formed by stacking a metasurface A (4) and a metasurface B (5), the two are spaced 200 μm apart, and the metasurface B (5) can move in the XOY plane, and the central wavelength of the visible light laser (3) is 0.488 μm.

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

[0046] like Figure 4-5 , which are a top view and a side view of the image generating 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 a plurality of 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 translational 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 outgoing wave of the metasurface B constituting the image generation unit of the image generation device. Ρ∈{1,2,3,4,5,6,7,8,9}, Ρ represents different pictures;

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

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

[0052] Here the command

[0053] Step 3: Give the output wave phase distribution of the metasurface B a tilt factor θ, Subtracting the incident wave phase distribution of metasurface B can obtain the phase distribution of metasurface B, and the complex amplitude of metasurface B is:

[0054]

[0055] Here the command

[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 the metasurface A by using the Rayleigh-Sommerfeld formula is as follows:

[0058] With the help of the Rayleigh-Sommerfeld diffraction formula, The transmission phase distribution function of metasurface A with a distance d from metasurface B is inverted for the initial condition.

[0059]

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

[0061] Through a series of simulations based on rigorous coupled wave analysis and time-domain finite-difference 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 to 0.8μm, the period in the x and y directions was fixed to 0.2μm, and the operating wavelength was set to 0.488μm. Then, under this condition, the side length of the titanium dioxide nanorod antenna was scanned in the range of 50μm to 150μm with a step size of 0.0002μm. The phase covered 0~2π and the transmission coefficient was above 0.94. Figure 6 shown.

[0063] Figure 7 Phase distribution diagram of metasurfaces A and B provided in Example 1 of the present invention.

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

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

[0066] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above 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 in the scope of protection of the present invention.

Claims

1. A HUD image generating device based on a translation 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, and the image generation unit includes a metasurface A and a metasurface B; the emission control module outputs a control signal to an optical emission device, and the optical emission device outputs a laser to the image generation unit; the emission control module outputs a drive control signal to a drive control module, and the drive control module outputs a drive signal to a mechanical drive component, and the mechanical drive component drives the metasurface B to move; The metasurface A and metasurface B are light-transmitting materials, both of which include a substrate and a nanorod array located on the substrate; metasurface A is fixed, and metasurface B moves through a mechanical driving component, and the laser emitted by the optical generating device passes through metasurface A and metasurface B in turn to form an output image, and the formed image is projected in front of the windshield after passing through a small hole.

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

3. A HUD image generating device based on a translational reconstruction metasurface as claimed in claim 1, characterized in that: The method for determining the nanorod array patterns of the super surface A and the super surface B is: Step 1: Obtain the phase distribution of the outgoing wave of the metasurface B according to the image P using the GS algorithm based on the Rayleigh-Sommerfeld formula Step 2: Based on the characteristics of the in-plane translational freedom and the beam deflection freedom being the same and the generalized Snell's law, establish the x-direction translation variable s x , y-direction translation variable s y With the beam deflection angle θ, The functional relationship of the incident wave phase distribution function of the metasurface B is derived Assume that 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 is t1 is a constant, x, y represent the coordinate system where plane B is located; Step 3: Give the output wave phase distribution of the metasurface B a tilt factor θ, Subtract the incident wave phase distribution of metasurface B to obtain the phase distribution of metasurface B φ B , calculate the complex amplitude UB of the metasurface B as: in, represents the complex amplitude of the outgoing wave of the metasurface B obtained by the GS algorithm based on the Rayleigh-Sommerfeld formula for a single image, UB i represents the complex amplitude of the incident wave on the metasurface B, k0 represents the wave vector of light in vacuum, θ p represents the elevation angle, represents the azimuth, x B ,y B represents the plane B coordinate system, and n represents the total number of images to be displayed; By s x and y The change of can realize any angle deflection in the hemisphere; the elevation angle θ and azimuth angle in the deflection angle It is expressed as: in: Step 4: After obtaining the incident wave phase distribution function of metasurface B, calculate the phase distribution of metasurface A using the Rayleigh-Sommerfeld formula. With the help of the Rayleigh-Sommerfeld diffraction formula, The transmission phase distribution function of metasurface A on plane A with a distance d from plane B is inverted for the initial condition. in, represents the complex amplitude of the metasurface A, represents the complex amplitude of the incident wave on metasurface B, x A ,y A represents the coordinate system on plane A, d represents the distance between metasurfaces A and B in the propagation direction of light; Step 5: Encode the complex amplitude obtained in step 3 and step 4 through the dielectric nanorods, and calculate the corresponding phase distribution of the metasurface using the following formula:

4. A HUD image generating device based on a translational reconstruction metasurface as claimed in claim 3, characterized in that: The specific method of step 5 is: using dielectric nanorods with high co-polarization linear polarization transmittance, and determining the side length parameters of the dielectric nanorods at various positions in the metasurface according to the spatial phase distribution of the target light field.

Images