Design method of air imaging device based on equivalent negative refraction flat structure

Abstract

The application discloses a kind of air imaging device design methods based on equivalent negative refraction flat structure, comprising: establishing single layer mirror array simulation model;Determine the period of mirror array in single layer mirror array simulation model, the depth-width ratio of mirror, mirror reflecting material, mirror reflecting material thickness, mirror coating thickness;According to single layer mirror array simulation model, establish double equivalent negative refraction parallel flat structure.The mirror array structure parameters and material of the application are determined by simulation calculation, so as to improve the design and preparation efficiency, reduce development cycle, reduce cost.

Description

Technical Field

[0001] This invention belongs to the field of air imaging technology, and in particular relates to a design method for an air imaging device based on an equivalent negative refractive plate structure. Background Technology

[0002] Negative refraction, an electrodynamic phenomenon where the refracted and incident rays lie on the same side of the normal, can be achieved using materials with both negative permittivity and negative permeability. Only artificially constructed materials possess negative refractive index properties. However, traditional negative refractive materials are limited by high manufacturing costs, slow research progress, small achievable negative refraction angles, and remain in the laboratory stage, hindering large-scale application. For air imaging applications, negative refractive index materials can be designed as an equivalent negative refractive plate structure. Generally, the characteristic dimensions of this structure are much larger than the wavelength of visible light, allowing imaging to be achieved using an array of orthogonal mirrors. This technology utilizes the principle of light field reconstruction, using the equivalent negative refractive index plate structure to cause incident light to oscillate, reflect, and refract multiple times within the microstructure, refocusing it in the air to form an image. Based on this equivalent negative refractive index plate structure, an interactive air imaging system can be developed. This technology provides contactless, naked-eye 3D hollow display and interaction technology, projecting multi-channel environmental information into the air, shortening decision-making time, and improving information flow speed and operational efficiency.

[0003] Developed by Japan's Asukanet, the ASKA3D glass imaging panel projects an identical image of an object into the air as light from the image or object passes through a specially structured glass plate. Meanwhile, China's Dongchao Technology Co., Ltd. has commercialized its interactive holographic aerial imaging technology. Both companies' aerial imaging technologies are based on an equivalent negative refraction structure. This technology can be applied to various aspects of life, including airport and high-speed rail information displays, hospital registration machines, and contactless elevator floating buttons.

[0004] However, the existing technology reduces the light intensity of air imaging due to the multiple oscillations, reflections, and refractions of light within the microstructure, which affects the size, resolution, and imaging effect of the image. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a design method for an air imaging device based on an equivalent negative refractive plate structure. The method determines the structural parameters and materials of the reflector array of the air imaging device through simulation calculation, thereby improving design and fabrication efficiency, reducing development cycle, and lowering cost.

[0006] The objective of this invention is achieved through the following technical solution: a design method for an air imaging device based on an equivalent negative refractive plate structure, comprising: establishing a simulation model of a single-layer mirror array; determining the period of the mirror array, the aspect ratio of the mirror, the mirror material, the mirror thickness, and the mirror coating thickness in the simulation model of the single-layer mirror array; and establishing a double-layer equivalent negative refractive parallel plate structure based on the simulation model of the single-layer mirror array.

[0007] In the above-mentioned design method for an air imaging device based on an equivalent negative refractive plate structure, the simulation model of the single-layer reflector array is a periodic structure, and a single periodic structure is a cuboid structure. The upper and lower surface properties of the cuboid structure are set as reflective materials, while the other surfaces are all transmissive.

[0008] In the above design method for air imaging devices based on an equivalent negative refractive plate structure, the period of the mirror array needs to be much larger than the wavelength and much smaller than the overall length of the air imaging device.

[0009] In the above design method for an air imaging device based on an equivalent negative refractive plate structure, the period of the mirror array is 0.1 mm to 1 mm, and the thickness of the substrate is 500 μm.

[0010] In the above-mentioned design method for air imaging devices based on an equivalent negative refractive plate structure, the aspect ratio of the reflector is obtained by the ratio of the received power of the receiving surface of the single-layer reflector array simulation model to the incident power of the incident surface of the single-layer reflector array simulation model.

[0011] In the above design method for an air imaging device based on an equivalent negative refractive plate structure, the aspect ratio of the reflector is 2:1.

[0012] In the above design method for air imaging devices based on an equivalent negative refractive plate structure, the reflector material is aluminum.

[0013] In the above design method for an air imaging device based on an equivalent negative refractive plate structure, the thickness of the reflective material of the mirror is 30 nm.

[0014] In the above design method for an air imaging device based on an equivalent negative refractive plate structure, the coating thickness of the reflector is 30 nm.

[0015] In the above-mentioned design method for an air imaging device based on an equivalent negative refraction parallel plate structure, a double-layer equivalent negative refraction parallel plate structure is established by using two single-layer mirror array simulation models. The light source is a point light source, and the signal emitted by the light source can be decomposed into two orthogonal signals. The two mirror array structures in the double-layer equivalent negative refraction parallel plate structure process each signal separately. When the x-axis distance and y-axis distance between the light source and the air imaging device are equal, and the efficiency reaches its maximum, the aspect ratio of the two-layer parallel plate structure is equal to the aspect ratio of the single-layer parallel plate structure when the simulation efficiency is at its maximum.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) This invention establishes a device simulation model of a single-layer reflector array and proposes a design method to optimize the period p of the reflector array and the height h of the reflector. The optimization objective is to maximize the ratio of the received power on the virtual plane (receiving surface) on the right side of the device to the incident power on the left side of the device (incident surface). Through optimized design, preferred equivalent negative refractive plate structure parameters and suitable reflective materials are obtained, providing a technical basis for device fabrication.

[0018] (2) This invention proposes a design method for constructing an equivalent negative refraction plate structure using an orthogonal reflector array. The upper and lower reflector arrays are identical, and the reflective strips in the upper layer are at 90° to those in the lower layer, forming a two-layer orthogonal mirror structure with periodically arranged reflective strips. Both sides of the reflective strips are coated with an optimized metal film, allowing the incoming light to undergo total internal reflection after passing through the two-layer periodic structure, resulting in an equivalent negative refraction effect and producing an air image. This device is a non-sequential optical system, and it is proposed to use LightTools 8.4.0 for simulation design, and to determine the thickness of the reflective material of the reflector through FDTD simulation.

[0019] (3) The present invention establishes a device simulation model of a double-layer reflector array. Through simulation calculation, the equivalent negative refraction structure imaging size and the smallest resolvable feature size can be predicted. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0021] Figure 1 This is a flowchart illustrating the design process of the equivalent negative refractive plate structure of the present invention.

[0022] Figure 2 This is a schematic diagram of the optical path of the single-layer reflector array of the present invention;

[0023] Figure 3 This is a schematic diagram of the equivalent negative refraction parallel plate optical path of the present invention;

[0024] Figure 4(a) shows the magnitude of the received power of the virtual plane (image plane) on the right side of the single-layer reflector device of the present invention;

[0025] Figure 4(b) shows the magnitude of the incident power on the left side of the single-layer reflector device according to the present invention; Figure 5 This invention analyzes the effect of aspect ratio of single-layer mirror arrays with different period sizes on device efficiency.

[0026] Figure 6(a) is a schematic diagram of the calculated transmittance of Al with a thickness of 10 nm according to the present invention.

[0027] Figure 6(b) is a schematic diagram of the calculated reflectance curve of Al with a thickness of 10 nm according to the present invention;

[0028] Figure 6(c) is a schematic diagram of the calculated transmittance curve of Al with a thickness of 20 nm according to the present invention;

[0029] Figure 6(d) is a schematic diagram of the calculated reflectance curve of Al with a thickness of 20 nm according to the present invention;

[0030] Figure 6(e) is a schematic diagram of the calculated transmittance curve of Al with a thickness of 30 nm according to the present invention;

[0031] Figure 6(f) is a schematic diagram of the calculated reflectance curve of Al with a thickness of 30 nm according to the present invention;

[0032] Figure 6(g) is a schematic diagram of the calculated transmittance curve of Al with a thickness of 50 nm according to the present invention;

[0033] Figure 6(h) is a schematic diagram of the calculated reflectance curve of Al with a thickness of 50 nm according to the present invention;

[0034] Figure 7 This is a schematic diagram of the distance curve between the designed light source S and the device in this invention;

[0035] Figure 8(a) is a schematic diagram of the power curve of the receiving end of the device designed in this invention;

[0036] Figure 8(b) is a schematic diagram of the efficiency curve of the receiving end of the device designed in this invention;

[0037] Figure 9(a) is a schematic diagram of the simulation of the single-layer equivalent negative refraction parallel plate structure of the present invention;

[0038] Figure 9(b) is a schematic diagram of the energy distribution of the receiving surface in the simulation of the single-layer equivalent negative refractive parallel plate structure of the present invention;

[0039] Figure 10(a) is a structural diagram of the three-dimensional simulation of the equivalent negative refractive plate structure of the present invention;

[0040] Figure 10(b) shows the scatter distribution of light rays on the receiving surface of the three-dimensional simulation of the equivalent negative refractive plate structure of the present invention;

[0041] Figure 11 This is a simulated scatter plot of light rays on the receiving surface after adjusting the structural parameters of the present invention.

[0042] Figure 12 This is a scatter plot of light rays on the receiving surface in the simulation of the finite area light source of the present invention. Detailed Implementation

[0043] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0044] To improve the resolution and imaging effect of air imaging by designing an air imaging device based on an equivalent negative refractive index (ERI) plate structure, this application discloses a design method for an air imaging device based on an ERI plate structure. By establishing a theoretical model and simulation algorithm for air imaging using an ERI plate structure, the imaging effects of a single-layer mirror array structure point source, an ERI plate structure point source, and an ERI plate structure finite-area source are analyzed. This demonstrates that a luminous object can form an image of the same size in the air after passing through the device, and establishes the minimum resolvable feature size of this image structure. The design method of this application also allows for the selection of optimized mirror array structure parameters, metal reflective film materials, and thicknesses to further improve the air imaging effect. The design process is as follows: Figure 1 As shown.

[0045] The design method for an air imaging device based on an equivalent negative refractive plate structure includes:

[0046] Establish a simulation model of a single-layer mirror array;

[0047] Determine the period of the mirror array, the aspect ratio of the mirrors, the mirror material, the thickness of the mirror reflective material, and the thickness of the mirror coating in the simulation model of a single-layer mirror array;

[0048] A double-layer equivalent negative refraction parallel plate structure was established based on a simulation model of a single-layer mirror array.

[0049] The simulation model of the single-layer reflector array is a periodic structure. Each periodic structure is a cuboid structure. The top and bottom surfaces of the cuboid structure are set to reflective material, while the other surfaces are transmissive.

[0050] The period of the mirror array needs to be much larger than the wavelength but much smaller than the overall length of the air imaging device. The period of the mirror array is 0.1 mm to 1 mm, and the substrate thickness is 500 μm.

[0051] An air imaging device is designed as a double-layered equivalent negative refractive parallel plate structure. When an external light signal enters the equivalent negative refractive glass, the two layers of mirrors in the equivalent negative refractive plate structure reflect two orthogonal signals respectively, achieving air imaging through an array of orthogonal mirrors. The proposed design method first establishes a single-layered mirror array with a periodic structure. A line light source and a receiver are placed at equidistant positions on both sides of the device, with a metal reflector placed between the light source and receiver to block stray light for simulation calculations. Based on the optimization objective of the impact on device performance, the periodic structural parameters are designed, and the influence relationship between mirror material and thickness, and the emission wavelength of the light source on light efficiency is established. The optimal structural parameters are determined through simulation calculations of the single-layered mirror array, and then a double-layered equivalent negative refractive parallel plate structure is established for simulation and optimization.

[0052] The period p of the mirror array in the equivalent negative refractive plate structure needs to be much larger than the wavelength and much smaller than the overall length of the device. Furthermore, since this device is a non-sequential optical system, lightTools is used for simulation. A single-layer reflective array is created to determine the optimal structural parameters.

[0053] The period p of the mirror array is selected to be between 0.1 mm and 1 mm. The thickness of the substrate is much smaller than the wavelength, and is set to 500 μm.

[0054] The device structure and characteristic parameters are designed based on the optimization objective of its impact on device performance. The optimization objective is the ratio λ of the power received on the virtual plane (receiving surface) on the right side of the device to the power incident on the left side of the device (incident surface). The larger λ is, the higher the efficiency.

[0055] The periodic structure depth and width of the mirror array are designed based on the optimization objective λ that affects device performance. The efficiency λ varies with the depth-to-width ratio, and the efficiency is optimal when the depth-to-width ratio is 2:1.

[0056] The optimization objective λ of the influence of the optical properties of the mirror material on the device performance was evaluated. Simulations and analyses were conducted on three different metal materials: silver, aluminum, and copper, and aluminum (Al) was selected as the mirror material.

[0057] The reflective properties and absorption of mirror metal materials vary for different wavelengths of light. By optimizing the target λ that affects the device performance, the relationship between the emission wavelength of the light source and the efficiency is established.

[0058] In the simulation, the incident light wavelength is 400nm to 700nm (visible light band). The FDTD method is used to simulate the transmittance and reflectance of Al material with different thicknesses of the mirror, and the thickness of the mirror material is determined to be 30nm.

[0059] The optimal structural parameters were determined through simulation calculations using a single-layer mirror array. Then, a double-layer equivalent negative refraction parallel plate structure was established for simulation and optimization. The signal emitted by the luminous object / light source can be decomposed into two orthogonal signals, and the two-layer mirror array structure processes each signal separately. When the distances Dx and Dy between the light source S and the device are equal, and the efficiency is at its highest, the aspect ratio of the two-layer parallel plate structure is equal to the aspect ratio of the single-layer parallel plate structure when the simulation efficiency is at its maximum.

[0060] The imaging performance of the device is related to the period and height of the flat-panel mirror. When the size is much larger than the wavelength, the smaller the feature size (period and height), the better the imaging resolution.

[0061] First, a theoretical model of a single-layer mirror array structure is established.

[0062] I. Theoretical Model Establishment

[0063] Single-layer mirror array structure such as Figure 2 As shown.

[0064] Model assumptions:

[0065] 1. The substrate thickness and the height of the metal mirror are negligible relative to the propagation distance;

[0066] 2. The structural feature size is much larger than the wavelength, so the diffraction effect is negligible;

[0067] 3. The refractive index of the filling layer is equal to that of the substrate.

[0068] A line light source emits light rays that reach the i-th and (i+1)-th metal mirrors, with the emitted light rays making an angle α with the z-axis. z,i ,α z,i+1 When light rays are incident on a device, they are refracted. According to Snell's law, the relationship between the angle of refraction and the angle of incidence is as follows:

[0069] n0sin(α z,i ) = n t sin(α zt,i )

[0070] n0sin(α z,i+1 ) = n tsin(α zt,i+1 )

[0071] When light passes through a metal mirror, the angle of incidence of the light is:

[0072] β zt,i =|90°-α zt,i |

[0073] β zt,i+1 =|90°-α zt,i+1 |

[0074] According to the law of reflection, the angle of reflection is equal in magnitude and opposite in direction to the angle of incidence.

[0075] β' zt,i =β zt,i

[0076] β' zt,i+1 =β zt,i+1

[0077] The reflected ray exits the device, and the angle between the ray exiting the device and the air and the z-axis is:

[0078] γ zt,i =|90°-β' zt,i |

[0079] γ zt,i =|90°-β' zt,i |

[0080] Angle of refraction on the air side:

[0081] n0sin(γ z,i ) = n t sin(γ zt,i )

[0082] n0sin(γ z,i+1 ) = n t sin(γ zt,i+1 )

[0083] Solving the above equations simultaneously, we get:

[0084] γ z,i+1 =α z,i+1

[0085] γ z,i =α z,i

[0086] That is, the angles of incidence and refraction of the two light rays when they enter the device are equal. The height of the metal mirror is negligible relative to the propagation distance, and the z-coordinates of the two light rays when they reach the mirror are equal. According to geometric relationships, ΔABC and ΔDEF in the diagram are congruent, further leading to Lo = Li. Similarly, for light rays incident on other mirrors of the device, γ... z,1 =α zt,1 ,λ z,2 =α zt,2 ,...,γ z,n =α zt,n The light rays incident on each of the metal mirrors of the device converge at a single point, and the image distance is equal to the object distance.

[0087] For a double-layered orthogonal mirror array, such as Figure 3 As shown, the luminous object is decomposed into two light signals. The incident surfaces of the two light signals are perpendicular to the plane containing the orthogonal mirror array. When the light enters the orthogonal mirror array, the first layer of the mirror array reflects the light signal whose incident surface is perpendicular to the mirror surface, and the reflection angle is equal to the incident angle. Similarly, the second layer of the mirror array reflects the light signal whose incident surface is perpendicular to the mirror surface of the second layer of the mirror array. Therefore, the two layers of mirror array can reflect light rays of any aperture angle, and the light rays emitted by the object form a real image of the same size and upright after passing through the orthogonal mirror array.

[0088] II. Establishment of Simulation Model for Single-Layer Mirror Array

[0089] The above analysis shows that the two layers of metal mirrors in the equivalent negative refraction plate structure reflect two orthogonal signals respectively. Therefore, the parameters of the two mirror layers have no effect on the signal light orthogonal to them. Thus, a single-layer mirror array is first established to determine the optimal structural parameters, and then a double-layer equivalent negative refraction parallel plate structure is established for simulation and optimization.

[0090] Considering that the characteristic size of the equivalent negative refractive plate structure is much larger than the wavelength of visible light, and that the light rays do not have a fixed order when incident on each array of mirrors, this device is a non-sequential optical system. Therefore, LightTools 8.4.0 is used for simulation. Ray tracing in LightTools is non-linear; it only has a starting point and direction, without a predetermined order in which the light rays pass through surfaces in space. The starting point of the light ray can be located anywhere in space, and it propagates according to the laws of propagation in the optical elements it passes through until the propagation stops (the light ray cannot reach the optical surface in the model, encounters an absorber, etc.).

[0091] Based on the principles of X-ray optics, in an equivalent negative refractive parallel plate structure, the period of the mirror should be much greater than the wavelength and much smaller than the object distance. Therefore, the period p is chosen to be between 0.1 mm and 1 mm. The substrate thickness is much smaller than the wavelength, and is set to 500 μm.

[0092] The simulation model is configured as follows:

[0093] The simulated device is a single-layer mirror array, which is a periodic structure. Therefore, a periodic mirror array structure is created first, and then the array is formed. Each periodic structure is a cuboid. Since the thickness of the mirror material is negligible relative to the period, the top and bottom surfaces of the cuboid are directly set to reflective material, such as aluminum, during modeling. All other surfaces are transmissive, and losses due to reflection and refraction are considered.

[0094] The aforementioned cuboid was copied and repeatedly arranged in an array to form a single-layer mirror array. A receiver was added to the front surface of the device to monitor the power. Ray tracing was performed with as many ray tracing lines as possible, within the limits of computational resources. Rays emitted from the cylindrical light source partially reached the virtual plane on the right side of the device and converged. The height of the mirror array was h = 0.25 mm, the period p = 0.5 mm, the light source wavelength was 550 nm, and the mirror metal film material was aluminum. The power of the cylindrical light source was 1 W. The received power on the virtual plane (image plane) on the right side of the device was analyzed in relation to the incident power on the left side of the device. The results are shown in Figures 4(a) and 4(b): the incident power on the left side of the device was 0.06 W, and the light power reaching the virtual plane on the right side of the device was 0.01 W. Therefore, the computational efficiency... λ The figure is 16.7%. The next step is to try to optimize the device by changing the structural parameters to improve the optical power of the image plane.

[0095] III. Optimization of Structural Parameters for Single-Layer Mirror Array

[0096] 1. The impact of structural depth and width on device performance

[0097] First, the period p and the height h of the reflector array are optimized. In this design, different parameters p and h will be scanned. The period p needs to be much larger than the wavelength and much smaller than the overall length of the device. Therefore, the range of p is determined to be 0.125mm-1mm, and it is changed in 0.125mm increments. The height variation range is determined according to the aspect ratio. Considering the processing factors, the aspect ratio range is 1:2 to 4:1. The optimization goal is to maximize the ratio of the received power on the virtual plane (receiving surface) on the right side of the device to the incident power on the left side of the device (incident surface).

[0098] from Figure 5 The results show that efficiency varies with aspect ratio, and the efficiency is optimal at an aspect ratio of 2:1, reaching 49%.

[0099] 2. The relationship between mirror material and efficiency

[0100] In the visible light band, there are many materials used to make mirrors, such as silver and aluminum. This design focuses on the simulation and analysis of three different metal materials: silver, aluminum, and copper.

[0101] The simulation results are as follows:

[0102] aluminum 0.06 0.029 copper 0.06 0.026 silver 0.06 0.028

[0103] Metal materials have little impact on efficiency. Since copper has low reflectivity in the visible light band, the efficiency is lowest when copper is used for the mirror. The efficiency difference is not significant when the material is replaced with silver or aluminum. Considering that silver is easily oxidized in the air, the reflectivity will drop significantly, while aluminum is not easily oxidized and has the highest efficiency, aluminum is chosen as the metal mirror material.

[0104] 3. The effect of light source emission wavelength on efficiency

[0105] Metals have different reflectivities and absorption rates for different wavelengths of light. The following simulation analysis will examine the impact of different wavelengths (bands) of light sources on the efficiency of the device, with aluminum selected as the metal material.

[0106] The light source wavelengths were set to the visible light band at 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, and 700nm. The simulation results are shown in the table below.

[0107]

[0108] Aluminum has a high reflectivity to visible light, so the wavelength of the light source has little effect on the efficiency.

[0109] 4. Simulation of the reflectivity of aluminum (Al) with different thicknesses using the FDTD method.

[0110] We plan to coat two surfaces of a 2mm x 60mm reflective strip microstructure with Al reflective material. The simulated incident light wavelength is 400nm to 700nm. The transmittance and reflectance of Al with different thicknesses are simulated using the FDTD method, as follows:

[0111] The transmittance of 10nm thick Al is shown in Figure 6(a), and the reflectance is shown in Figure 6(b).

[0112] The transmittance of 20nm thick Al is shown in Figure 6(c), and the reflectance is shown in Figure 6(d).

[0113] The transmittance of 30nm thick Al is shown in Figure 6(e), and the reflectance is shown in Figure 6(f).

[0114] The transmittance of 50nm thick Al is shown in Figure 6(g), and the reflectance is shown in Figure 6(h).

[0115] When the Al thickness is 30nm, the broadband transmittance is less than 1%, which meets the requirements. As the coating thickness increases, the cost increases and the surface roughness increases, resulting in a decrease in device reflectivity. Therefore, the optimal coating thickness is 30nm.

[0116] IV. Establishment of Simulation Model for Double-Layer Mirror Array / Equivalent Negative Refraction Parallel Plate Structure

[0117] Using LightTools software, an equivalent negative refraction parallel plate structure was constructed for simulation. As shown in the theoretical analysis in the first part, the signal emitted by the luminous object / light source can be decomposed into two orthogonal signals, and the two-layer mirror array structure processes each signal separately. The direction of light propagation is perpendicular to the plane of the paper. When the distances Dx and Dy between the light source S and the device are equal, such as... Figure 7 As shown, when the efficiency reaches its maximum, the aspect ratio of the two-layer parallel plate structure is equal to the aspect ratio of the single-layer parallel plate structure when the simulation efficiency is at its maximum.

[0118] Therefore, software was first used to copy the single-layer reflector array and, after movement and rotation, establish an equivalent negative refraction parallel plate structure. The light source was replaced with a point source, ensuring that Dx = Dy. The simulation results are shown in Figures 8(a) and 8(b). After passing through the device, the point source converges to a single point on the receiving surface. Due to the absorption of the reflector and the fact that some light is not reflected when passing through the second layer device, the receiving power and efficiency are lower than those of the single-layer reflector array. Under the illumination of a 1W point source, the power reaching the left side of the equivalent negative refraction plate is 0.0464W, the received power is 0.0166W, and the efficiency is 35.8%.

[0119] V. Imaging Analysis of Finite-Area Light Sources Based on Equivalent Negative Refractive Plate Structure

[0120] First, we consider a simpler two-dimensional case to examine its imaging principle. As shown in Figure 9(a), the structure is a single-layer mirror array structure with infinite length in the y-direction. The mirror height h = 1 mm, thickness 100 nm, and array period p = 2 mm. A line source and a receiver are placed at equal distances on both sides of the device. A metal reflector is placed between the source and receiver to block stray light. In the simulation results, the light emitted from the line source forms a corresponding image at equidistant, opposite positions on the other side of the device after passing through the device. Figure 9(b) shows the energy distribution of the light emitted from the line source on the image plane after passing through the device. The energy is concentrated in an area 50 mm long and about 3 mm wide, indicating that the line source can form a corresponding image after passing through the device, and the object and image are of equal size.

[0121] Preliminary simulation results of the equivalent negative refractive plate structure (3D):

[0122] A model as shown in Figure 10(a) was created in LightTools. The device size was 50mm × 50mm × 4mm, and the characteristic parameters of the mirror array structure were the same as in step 1. The parameters of the left and right halves of the equivalent negative refractive plate structure were the same, and the right half was rotated 90° relative to the left half about the z-axis. A metal plate was placed below the device to block stray light. A point source and a receiver were placed at equal distances on both sides of the device. The light emitted by the point source converged at the receiver after passing through the device, and the image distance was equal to the object distance. In the scatter plot 10(b), it can be seen that the light emitted by the point source formed a diffuse spot of about 3mm*1.5mm on the image plane after passing through the device, indicating that the smallest resolvable feature size of the structure is currently 3mm horizontally and 1.5mm vertically.

[0123] The slot depth h and width d of the device are reduced to 0.25 mm and 0.25 mm respectively, while other parameters remain unchanged. The scatter distribution at the receiving end is as follows: Figure 11 As shown, the diffuse spot size is reduced to 0.3mm × 0.2mm, and further reduction of the feature size can further improve the resolution.

[0124] To simulate real-world usage, a finite-area light source with an area of ​​25mm × 25mm was used in the simulation. The scatter plot on the receiver is shown below. Figure 12 As shown, the light energy is distributed in an area of ​​approximately 25mm × 25mm, proving that the luminous object forms an image of the same size at equidistant positions after passing through the device.

[0125] This invention establishes a device simulation model of a single-layer mirror array and proposes a design method to optimize the period p of the mirror array and the height h of the mirrors. The optimization objective is to maximize the ratio of the received power on the virtual plane (receiving surface) on the right side of the device to the incident power on the left side of the device (incident surface). Through optimized design, preferred equivalent negative refractive plate structure parameters and suitable reflective materials are obtained, providing a technical foundation for device fabrication. This invention also proposes a design method for constructing an equivalent negative refractive plate structure using an orthogonal mirror array. The upper and lower layer mirror arrays are identical, and the reflective strips in the upper layer are at 90° to those in the lower layer, forming a two-layer orthogonal mirror structure with periodically arranged reflective strips. Both sides of the reflective strips are coated with an optimized metal film, allowing the incoming light to undergo total internal reflection after passing through the two periodic structures, resulting in an equivalent negative refractive effect and producing an aerial image. This device is a non-sequential optical system, and LightTools 8.4.0 is proposed for simulation design. This invention also establishes a device simulation model of a double-layer mirror array. Through simulation calculations, the image size of the equivalent negative refractive structure and the smallest resolvable feature size can be predicted.

[0126] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A design method for an air imaging device based on an equivalent negative refractive plate structure, characterized in that... include: Establish a simulation model of a single-layer mirror array; Determine the period of the mirror array, the aspect ratio of the mirror, the reflective material of the mirror, the thickness of the reflective material, and the coating thickness of the mirror in the simulation model of the single-layer mirror array. A double-layer equivalent negative refraction parallel plate structure is established based on the simulation model of a single-layer mirror array. The simulation model of the single-layer reflector array is a periodic structure, and a single periodic structure is a cuboid structure. The upper and lower surfaces of the cuboid structure are set to reflective material, while the other surfaces are transmissive. The period of the mirror array needs to be much larger than the wavelength and much smaller than the overall length of the air imaging device. The period of the mirror array is 0.1mm~1mm, and the thickness of the substrate is 500um; The aspect ratio of the mirror is obtained by comparing the received power at the receiving surface of the single-layer mirror array simulation model with the incident power at the incident surface of the single-layer mirror array simulation model. The aspect ratio of the reflector is 2:1; A double-layer equivalent negative refraction parallel plate structure is established by simulating two single-layer mirror arrays. The light source is a point source, and the signal emitted by the light source can be decomposed into two orthogonal signals. The two mirror arrays in the double-layer equivalent negative refraction parallel plate structure process each signal separately. When the x-axis distance between the light source and the air imaging device is equal to the y-axis distance, the efficiency reaches its maximum. The aspect ratio of the double-layer parallel plate structure is equal to the aspect ratio of the single-layer parallel plate structure when the simulation efficiency is maximized.

2. The design method for an air imaging device based on an equivalent negative refractive plate structure according to claim 1, characterized in that: The reflective material of the mirror is aluminum.

3. The design method for an air imaging device based on an equivalent negative refractive plate structure according to claim 1, characterized in that: The reflective material of the mirror is 30nm thick.

4. The design method for an air imaging device based on an equivalent negative refractive plate structure according to claim 1, characterized in that: The coating thickness of the reflector is 30nm.

Images