Bionic wading color restoration system based on liquid crystal controlled superstructure surface

Abstract

The application discloses a kind of based on liquid crystal control's super-structured surface biomimetic wading color restoration system, comprising: liquid crystal polarized light control module, super-structured surface array, power module, polarization switch module, transparent display module and wading imaging module;Liquid crystal polarized light control module is used to adjust the polarization state of incident light to change the filtering ratio of different color light;Super-structured surface array is used to filter the incident light after passing through liquid crystal polarized light control module by its polarization sensitivity, and change the transmission spectrum of filter light;Power module is used to power supply for biomimetic wading color restoration system;Polarization switch module is used to control liquid crystal polarized light control module;Transparent display module is used to display underwater depth and distance in real time, and wading imaging module is used to underwater imaging according to the filter light of super-structured surface array.The application can improve underwater imaging quality and improve underwater color while ensuring real-time observation.

Description

Technical Field

[0001] This invention relates to the fields of biomimetic displays and near-eye displays, and in particular to a biomimetic water-resistant color reproduction system based on a metasurface with liquid crystal modulation. Background Technology

[0002] Underwater optical imaging offers advantages such as intuitive target detection, high imaging resolution, and rich information content. However, due to the absorption and scattering characteristics of the water medium, achieving clear real-time underwater observation is far from easy. Firstly, there's absorption: water molecules and various media in the water absorb light. Furthermore, water absorption exhibits distinct spectral characteristics; water molecules tend to absorb red light, while suspended particles primarily absorb green light. This leads to different types of color distortion in images acquired under varying aquatic environments. Another factor affecting imaging is scattering. Scattering also loses energy and shortens the imaging distance; light from the target object encountering dust will undergo forward scattering, causing the image to become blurry; ambient light encountering dust and then scattering into the lens is called backscattering, which has the greatest impact on imaging results and, in severe cases, may prevent image generation.

[0003] With the development of electronic information technology, people have placed higher demands on underwater optical imaging. Existing underwater vision technologies can improve underwater imaging quality through image processing. However, these technologies often rely on software-based image processing rather than optical optimization, making real-time observation difficult. Summary of the Invention

[0004] The applicant's research revealed that with the development and maturation of micro-nano fabrication technology, metasurfaces have become possible for manufacturing and application. Therefore, placing metasurfaces with wavefront and phase modulation capabilities in front of lenses can significantly reduce color distortion caused by water absorption and scattering. Skylight has a relatively stable polarization distribution. Based on Rayleigh scattering theory and using the Stokes vector and horizontal coordinate system, a simple model of skylight polarization distribution can be established. Therefore, observing the sky at a specific time and location can yield a stable light polarization distribution map, providing information on the polarization degree and polarization azimuth of the target. The microvilli in the compound eye structure of insects acquire polarization information from the sky through their structural asymmetry, enabling polarization navigation. Metasurfaces are similar to the microvilli in compound eyes; through their structural asymmetry and sensitivity to polarized light, they allow for adjustment of the color filter ratio by regulating the polarization of the incident light. The adjustment of polarization is achieved through the optical rotation properties of electro-liquid crystals; these properties allow for continuous adjustment of the incident light, thereby regulating the color filter ratio. Therefore, applying metasurface technology to underwater imaging can improve image quality.

[0005] In view of the aforementioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a biomimetic underwater color restoration system based on a metasurface controlled by liquid crystal, which aims to improve underwater imaging quality and enhance underwater color while ensuring real-time observation.

[0006] To achieve the above objectives, the present invention provides a biomimetic water-based color reproduction system based on a metasurface regulated by liquid crystal. The biomimetic water-based color reproduction system includes: a liquid crystal polarization light regulation module, a metasurface array, a power supply module, a polarization switch module, a transparent display module, and a water-based imaging module.

[0007] The liquid crystal polarization light control module is used to adjust the polarization state of the incident light in order to change the filtering ratio of different colors of light.

[0008] The metasurface array is used to filter incident light after passing through the liquid crystal polarization light modulation module by means of its polarization sensitivity, and to change the transmission spectrum of the filtered light; wherein, the number of micro-nano metasurface units in the metasurface array is M×N, where M and N are both natural numbers greater than or equal to 2.

[0009] The power module is used to supply power to the biomimetic water-based color reproduction system;

[0010] The polarization switch module is used to control the liquid crystal polarization light modulation module;

[0011] The transparent display module is used to display detection information in real time, including underwater depth and distance;

[0012] The water-based imaging module is used to perform underwater imaging based on the filtered light from the metasurface array.

[0013] The biomimetic wading color restoration system is configured as follows: in response to an underwater imaging signal, the liquid crystal polarization light control module performs polarization filtering on the natural light entering the biomimetic wading color restoration system to obtain initial incident polarized light; the liquid crystal polarization light control module adjusts the polarization state of the initial incident polarized light by controlling the deflection of the liquid crystal therein to change the filtering ratio of different colors of light to obtain adjusted polarized light; the metasurface array filters the adjusted polarized light to obtain the required polarized light; and the wading imaging module performs underwater imaging according to the required polarized light.

[0014] Optionally, the structure of the micro / nano metasurface unit is two intersecting rectangular nanoblocks in a cross shape, and a nanocylinder is nested at the intersection of the two rectangular nanoblocks; the liquid crystal polarization light control module continuously adjusts the polarization state of the light, thereby adjusting the filtering ratio of green light and blue light; the micro / nano metasurface unit filters blue light and green light respectively in mutually perpendicular polarization directions.

[0015] Optionally, the liquid crystal polarization light control module includes a polarizer, a light alignment layer, a liquid crystal molecule layer, and a transparent electrode; wherein the transparent electrode has two arrangement methods, one is distributed on the side of the liquid crystal molecule layer, and the other is distributed on the front of the liquid crystal molecule layer.

[0016] Optionally, the metasurface array comprises a substrate and a micro / nano grating array; the substrate is made of a material with a refractive index of 1-2; the micro / nano grating array is made of a material with a refractive index of 2-4; the micro / nano grating array is composed of multiple micro / nano grating units, each of which is a micro / nano metasurface unit, and the gaps between the arrays of micro / nano grating units are filled with a material whose refractive index is between that of the substrate material and the grating array; the structure of the micro / nano grating unit is two intersecting rectangular nanoblocks in a cross shape, and a nanocylinder is nested at the intersection of the two rectangular nanoblocks.

[0017] Optionally, the period of the micro / nano metasurface unit is 100nm-500nm, the length, width, and radius of the micro / nano metasurface unit are all 30nm-450nm, and the height of the micro / nano metasurface unit is 50nm-450nm.

[0018] Optionally, the process of obtaining the period, length, width, and height of the micro / nano metasurface unit includes:

[0019] The spectral response curves of materials corresponding to micro-nano metasurfaces with different lengths, widths, periods, and heights were simulated using the RCWA algorithm to construct the first dataset;

[0020] A GAN network architecture is constructed, and the relationship between the material structure and the spectral response curve of the micro-nano metasurface is learned using the first dataset to train and obtain the GAN network model.

[0021] Based on the spectrum of the target filtered light corresponding to the micro / nano metasurface unit, the period, length, width, and height of the micro / nano metasurface unit are obtained using the GAN network module.

[0022] Optionally, the optimization process for the period, length, width, and height of the micro / nano metasurface unit includes:

[0023] The average transmittance for wavelengths from 400 nm to 490 nm is calculated as blue light transmittance t1, with a standard deviation a1; the average transmittance for wavelengths from 491 nm to 570 nm is calculated as green light transmittance t2, with a standard deviation a2; and the average transmittance for wavelengths from 571 nm to 700 nm is calculated as red light transmittance t3, with a standard deviation a3. The standard deviation is used to describe the dispersion of transmittance measurements within the same set of wavelengths.

[0024] By using a gradient descent-based reinforcement learning algorithm, the errors of t1, t2, t3 and the required transmittance are reduced during the process of iteratively optimizing the length, width, period, and height of the micro-nano metasurface unit. At the same time, the standard deviations a1, a2, a3 are constrained to be at a low level, thereby increasing the smoothness of the optimized micro-nano metasurface unit.

[0025] Optionally, the transparent display module includes a transparent electrode, a transparent monochromatic LED, and a superlens.

[0026] Optionally, the metasurface array can be configured in the following ways: embedded in the frame of the biomimetic water-based color reproduction system, embedded in the lens of the biomimetic water-based color reproduction system, pasted onto the lens of the biomimetic water-based color reproduction system, or grown directly on the lens of the biomimetic water-based color reproduction system.

[0027] The beneficial effects of this invention are as follows: 1. Responding to underwater imaging signals, the liquid crystal polarization light control module performs polarization filtering on the natural light entering the biomimetic wading color restoration system to obtain initial incident polarized light; the liquid crystal polarization light control module adjusts the polarization state of the initial incident polarized light by controlling the deflection of the liquid crystal within it, thereby changing the filtering ratio of different colors of light to obtain adjusted polarized light; the metasurface array filters the adjusted polarized light to obtain the desired polarized light; the wading imaging module performs underwater imaging based on the desired polarized light. This invention combines the principle of insect polarization navigation, utilizing the polarization sensitivity of metasurfaces to light and the optical rotation characteristics of liquid crystals. By continuously adjusting the polarization state of the incident light through electro-controlled liquid crystals, the transmittance of different colors of light and the filtering of the desired color light by the metasurface are adjusted, solving the problem of image color distortion caused by the uneven absorption and color scattering of light by particles in water. 2. The structure of the micro / nano metasurface unit of this invention consists of two intersecting rectangular nanoblocks arranged in a cross shape, with a nanocylinder nested at the intersection of the two rectangular nanoblocks. The liquid crystal polarization control module continuously adjusts the polarization state of the light, thereby adjusting the filtering ratio of green and blue light. The micro / nano metasurface unit filters blue and green light respectively in mutually perpendicular polarization directions. Because different wavelengths of light have different attenuation rates in an underwater environment, red light has a longer wavelength and the weakest penetration ability, typically disappearing first at a depth of 3-4 meters underwater. Blue and green light, on the other hand, have shorter wavelengths and travel further in water. Due to the most severe attenuation of the red component, images acquired underwater contain very little red; while the information in the blue and green channels is relatively well preserved. This invention effectively adjusts the transmittance of blue and green light, increasing the brightness or saturation of the blue and green channels to compensate for the lack of red light in the underwater environment, thus more effectively improving image color distortion and enhancing color reproduction. 3. This invention uses a metasurface array to biomimic the compound eyes of insects, which can effectively filter the light of the desired color and further improve the problem of image color distortion.

[0028] In summary, this invention no longer relies solely on image processing technology, but rather utilizes the polarization sensitivity of metasurfaces and the optical rotation properties of liquid crystals to improve underwater imaging quality and enhance underwater color while ensuring real-time observation. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a biomimetic water-based color reproduction system based on a metasurface controlled by liquid crystal, provided in a specific embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the liquid crystal polarization light modulation module with transparent electrodes on the side and the metasurface array provided in a specific embodiment of the present invention;

[0031] Figure 3 yes Figure 2 A schematic diagram showing the deflection of liquid crystal molecules and the polarization state of light when no voltage is applied or the voltage is less than the threshold voltage;

[0032] Figure 4 yes Figure 2 A schematic diagram showing the deflection of liquid crystal molecules and the polarization state of light when an applied voltage is greater than or equal to the saturation voltage;

[0033] Figure 5 yes Figure 2 A schematic diagram showing the deflection of liquid crystal molecules and the polarization state of light when an applied voltage is greater than the threshold voltage;

[0034] Figure 6 This is a schematic diagram of the structure of the transparent electrode on the positive side of the liquid crystal polarization light control module and the metasurface array provided in a specific embodiment of the present invention;

[0035] Figure 7 yes Figure 6 A schematic diagram showing the deflection of liquid crystal molecules and the polarization state of light when no voltage is applied or the voltage is less than the threshold voltage;

[0036] Figure 8 yes Figure 6 A schematic diagram showing the deflection of liquid crystal molecules and the polarization state of light when an applied voltage is greater than or equal to the saturation voltage;

[0037] Figure 9 yes Figure 6 A schematic diagram showing the deflection of liquid crystal molecules and the polarization state of light when an applied voltage is greater than the threshold voltage;

[0038] Figure 10 This is a top view schematic diagram of a micro / nano metasurface unit specifically provided by the present invention. Detailed Implementation

[0039] This invention discloses a biomimetic water-based color reproduction system based on a metasurface controlled by liquid crystals. Those skilled in the art can refer to the content of this document and appropriately modify the technical details to achieve the desired result. It is particularly important to note that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0040] The applicant's research revealed that with the development and maturation of micro-nano fabrication technology, metasurfaces have become possible for manufacturing and application. Therefore, placing metasurfaces with wavefront and phase modulation capabilities in front of lenses can significantly reduce color distortion caused by water absorption and scattering. Skylight has a relatively stable polarization distribution. Based on Rayleigh scattering theory and using the Stokes vector and horizontal coordinate system, a simple model of skylight polarization distribution can be established. Therefore, observing the sky at a specific time and location can yield a stable light polarization distribution map, providing information on the polarization degree and polarization azimuth of the target. The microvilli in the compound eye structure of insects acquire polarization information from the sky through their structural asymmetry, enabling polarization navigation. Metasurfaces are similar to the microvilli in compound eyes; through their structural asymmetry and sensitivity to polarized light, they allow for adjustment of the color filter ratio by regulating the polarization of the incident light. The adjustment of polarization is achieved through the optical rotation properties of electro-liquid crystals; these properties allow for continuous adjustment of the incident light, thereby regulating the color filter ratio. Therefore, applying metasurface technology to underwater imaging can improve image quality.

[0041] Therefore, embodiments of the present invention provide a biomimetic water-resistant color reproduction system based on a metasurface controlled by liquid crystal, such as... Figure 1-10 As shown, the biomimetic water-based color reproduction system includes: a liquid crystal polarization light control module 1, a metasurface array 2, a power supply module 3, a polarization switch module 4, a transparent display module 5, and a water-based imaging module 6.

[0042] The liquid crystal polarization light control module 1 is used to adjust the polarization state of the incident light in order to change the filtering ratio of different colors of light.

[0043] Metasurface array 2 is used to filter incident light after passing through liquid crystal polarization light modulation module 1 by means of its polarization sensitivity, and to change the transmission spectrum of the filtered light; wherein, the number of micro-nano metasurface units 12 in metasurface array 2 is M×N, where M and N are both natural numbers greater than or equal to 2.

[0044] Power module 3 is used to power the biomimetic water-based color reproduction system;

[0045] The polarization switch module 4 is used to control the liquid crystal polarization light modulation module 1;

[0046] Transparent display module 5 is used to display detection information in real time, including underwater depth and distance;

[0047] The wading imaging module 6 is used to perform underwater imaging based on the filtered light from the metasurface array 2.

[0048] The biomimetic wading color restoration system is configured as follows: In response to an underwater imaging signal, the liquid crystal polarization light control module 1 performs polarization filtering on the natural light entering the biomimetic wading color restoration system to obtain initial incident polarized light; the liquid crystal polarization light control module 1 adjusts the polarization state of the initial incident polarized light by controlling the liquid crystal deflection therein to change the filtering ratio of different colors of light to obtain adjusted polarized light; the metasurface array 2 filters the adjusted polarized light to obtain the required polarized light; and the wading imaging module 6 performs underwater imaging according to the required polarized light.

[0049] It should be noted that the selective absorption of light by water and the scattering of light by suspended particles in the water are the main causes of underwater imaging distortion. This invention can adjust the color filter ratio by regulating the polarization of incident light through the optical rotation of liquid crystals and the polarization sensitivity of metasurfaces. This can partially compensate for the absorption and scattering of light by water, thereby improving the distortion of underwater images. The micro / nano metasurface filters visible light to different degrees through a mechanism similar to compound eye polarization navigation. By using electro-controlled liquid crystals to change the polarization state of the incident light, and due to the polarization sensitivity of the metasurface, the transmission spectrum is altered, achieving accurate color reproduction in water.

[0050] It is worth mentioning that the present invention is willing to obtain light with a shorter wavelength by filtering. Light with a shorter wavelength can travel a longer distance in water, which can make the image information relatively intact and effectively alleviate the problem of image distortion.

[0051] In this specific embodiment, the liquid crystal polarization light control module 1 adjusts the polarization state of the incident light by electrically controlling the deflection of the liquid crystal; the liquid crystal polarization light control module 1 continuously controls the deflection of the liquid crystal by controlling the magnitude of the voltage, thereby achieving the effect of continuously changing the polarization of the incident light.

[0052] In this specific embodiment, the structure of the micro-nano metasurface unit 12 is two intersecting rectangular nanoblocks 13 in a cross shape, and a nanocylinder 14 is nested at the intersection of the two rectangular nanoblocks 13; the liquid crystal polarization light control module 1 continuously adjusts the polarization state of the light, thereby adjusting the filtering ratio of green light and blue light; the micro-nano metasurface unit 12 filters blue light and green light respectively in mutually perpendicular polarization directions.

[0053] The design method of the micro-nano metasurface unit 12 is to design two nanoblocks respectively, and when they are stacked together, a cylindrical structure is nested in the middle, which can effectively reduce the change in spectral response caused by the stacking of two nanoblocks compared to a single nanoblock.

[0054] A top view of the micro / nano metasurface unit 12 can be seen as follows Figure 10 As shown.

[0055] It should be noted that water absorbs long-wavelength light such as red and orange light more strongly, while absorbing short-wavelength light such as blue and green light less strongly. This results in underwater images often appearing with a blue-green hue. Red light has a longer wavelength and the weakest penetrating power, typically disappearing first at a depth of 3-4 meters underwater. Blue and green light, on the other hand, have shorter wavelengths and travel farther in water. Because the red component attenuates the most, underwater images contain very little red; while the information in the blue and green channels is relatively well preserved. This invention effectively adjusts the transmittance of blue and green light, increasing the brightness or saturation of the blue and green channels to compensate for the lack of red light in the underwater environment. This can more effectively improve image color distortion and enhance color reproduction.

[0056] In this specific embodiment, such as Figure 2 and Figure 6 As shown, the liquid crystal polarization light control module 1 includes a polarizer 7, a light alignment layer 8, a liquid crystal molecular layer 9, and a transparent electrode 10; wherein, the transparent electrode 10 has two arrangement methods, one of which is distributed on the side of the liquid crystal molecular layer 9 (e.g., Figure 2 As shown), a type of distribution on the front side of the liquid crystal molecule layer 9 (e.g.) Figure 6 (As shown).

[0057] In this specific embodiment, the metasurface array 2 comprises a substrate 11 and a micro / nano grating array; the substrate 11 is made of a material with a refractive index of 1-2; the micro / nano grating array is made of a material with a refractive index of 2-4; the micro / nano grating array is composed of multiple micro / nano grating units, each of which is a micro / nano metasurface unit 12, and the gaps between the arrays of each micro / nano grating unit are filled with a material whose refractive index is between that of the substrate material and the grating array; the structure of the micro / nano grating unit is that two intersecting rectangular nanoblocks 13 form a cross shape, and a nanocylinder 14 is nested at the intersection of the two rectangular nanoblocks 13.

[0058] Furthermore, the substrate 11 can be made of silicon oxide. The micro / nano grating array can be made of hydrogenated amorphous silicon.

[0059] In this specific embodiment, the period of the micro / nano metasurface unit 12 is 100nm-500nm, the length, width, and radius of the micro / nano metasurface unit 12 are all 30nm-450nm, and the height of the micro / nano metasurface unit 12 is 50nm-450nm. The radius can be the radius of the nanocylinder 14.

[0060] In this specific embodiment, the process of obtaining the period, length, width, and height of the micro / nano metasurface unit 12 includes:

[0061] The spectral response curves of materials corresponding to micro-nano metasurfaces with different lengths, widths, periods, and heights were simulated using the RCWA algorithm to construct the first dataset;

[0062] A GAN network architecture was constructed, and the relationship between the material structure and the spectral response curve of the micro-nano metasurface was learned using the first dataset to train and obtain the GAN network model.

[0063] Based on the spectrum of the target filtered light corresponding to the micro-nano metasurface unit 12, the period, length, width, and height of the micro-nano metasurface unit 12 are obtained using a GAN network model.

[0064] It should be noted that by obtaining the relationship between the material structure and its spectral response curve of micro / nano metasurfaces through machine learning, the structure can be inferred from the required spectrum. Machine learning can better capture the relationship between material structure (shape and size) and spectral response curve. The RCWA algorithm, or Rigorous Coupled-Wave Analysis algorithm, is a numerical algorithm widely used to solve periodic electromagnetic field problems. The following is a detailed analysis of the RCWA algorithm. Based on Maxwell's equations and Floquet's theorem, the RCWA algorithm is used to simulate and analyze the interaction between electromagnetic waves and periodic optical structures. Its core idea is to decompose the electromagnetic field in the periodic structure into a series of spatial harmonics (Fourier series), and simulate the propagation and scattering of electromagnetic waves in the periodic structure by solving the coupled wave equations between these spatial harmonics. GAN networks, short for Generative Adversarial Networks, are powerful deep learning models that utilize two networks—a generator and a discriminator—for adversarial training.

[0065] In this specific embodiment, the optimization process for the period, length, width, and height of the micro / nano metasurface unit 12 includes:

[0066] The average transmittance of wavelengths from 400nm to 490nm is calculated as blue light transmittance t1, with standard deviation a1; the average transmittance of wavelengths from 491nm to 570nm is calculated as green light transmittance t2, with standard deviation a2; the average transmittance of wavelengths from 571nm to 700nm is calculated as red light transmittance t3, with standard deviation a3; where the standard deviation is used to describe the dispersion of transmittance measurements for the same set of wavelengths.

[0067] By using a gradient descent-based reinforcement learning algorithm, the errors of t1, t2, t3 and the required transmittance are reduced during the process of iteratively optimizing the length, width, period and height of the micro-nano metasurface unit 12. At the same time, the standard deviations a1, a2, a3 are constrained to be at a low level, thereby increasing the smoothness of the optimized micro-nano metasurface unit 12.

[0068] It should be noted that this embodiment further optimizes the preliminary structure of the obtained micro / nano metasurface unit 12 to achieve better results. Gradient descent reinforcement learning is a widely used optimization method within the reinforcement learning framework. By continuously adjusting the agent's behavioral policy parameters to minimize the loss function, it enables the agent to learn how to make decisions more effectively. This algorithm has wide applications in reinforcement learning, and combining it with appropriate optimization techniques can further improve training efficiency and performance.

[0069] In this specific embodiment, the transparent display module 5 includes a transparent electrode 10, a transparent monochromatic LED, and a superlens.

[0070] In this specific embodiment, the metasurface array 2 can be configured in the following ways: frame embedded in the biomimetic water-inspired color reproduction system, lens embedded in the biomimetic water-inspired color reproduction system, lens pasted onto the biomimetic water-inspired color reproduction system, or grown directly on the lens of the biomimetic water-inspired color reproduction system.

[0071] This invention achieves different color light filtering ratios by controlling the deflection of liquid crystal molecules.

[0072] In this specific embodiment, the transparent electrodes 10 are distributed on the side as follows: Figure 2 As shown, when no voltage is applied or the voltage is less than the threshold voltage, the deflection of liquid crystal molecules and the polarization state of light are as follows. Figure 3 As shown, Figure 3 In this process, the liquid crystal molecules rotate rather randomly.

[0073] With transparent electrodes 10 distributed on the side, when a voltage greater than or equal to the saturation voltage is applied, the deflection of the liquid crystal molecules and the polarization state of the light are as follows: Figure 4 As shown, Figure 4 In this system, all liquid crystal molecules are in a horizontal state.

[0074] Transparent electrodes 10 are distributed on the side. When a voltage greater than the threshold voltage is applied, the deflection of the liquid crystal molecules and the polarization state of the light are as follows: Figure 5 As shown, Figure 5 In this state, all liquid crystal molecules are in a state of uniform tilt angle deflection.

[0075] In another specific embodiment, the transparent electrodes 10 are distributed on the front side as shown. Figure 6As shown, when no voltage is applied or the voltage is less than the threshold voltage, the deflection of liquid crystal molecules and the polarization state of light are as follows. Figure 7 As shown, Figure 7 The liquid crystal molecules in the middle are deflected rather randomly.

[0076] With transparent electrodes 10 distributed on the front side, when a voltage greater than or equal to the saturation voltage is applied, the deflection of the liquid crystal molecules and the polarization state of light are as follows: Figure 8 As shown, Figure 8 In this system, all liquid crystal molecules are vertically deflected.

[0077] With transparent electrodes 10 distributed on the front side, when a voltage greater than the threshold voltage is applied, the deflection of the liquid crystal molecules and the polarization state of the light are as follows: Figure 9 As shown, Figure 9 In this state, all liquid crystal molecules are in a state of uniform tilt angle deflection.

[0078] In response to an underwater imaging signal, the liquid crystal polarization light control module 1 performs polarization filtering on the natural light entering the biomimetic wading color restoration system to obtain initial incident polarized light. The module then adjusts the polarization state of the initial incident polarized light by controlling the deflection of the liquid crystal within it, thereby changing the filtering ratio of different colors of light to obtain adjusted polarized light. The metasurface array 2 filters the adjusted polarized light to obtain the desired polarized light. The wading imaging module 6 performs underwater imaging based on the desired polarized light. This invention combines the principle of insect polarization navigation, utilizing the polarization sensitivity of metasurfaces to light and the optical rotation characteristics of liquid crystals. By continuously adjusting the polarization state of the incident light through electro-controlled liquid crystals, the transmittance of different colors of light and the filtering of the desired color light by the metasurface are adjusted, solving the problem of image color distortion caused by uneven absorption and color scattering of light by particles in water.

[0079] In this embodiment of the invention, the structure of the micro / nano metasurface unit 12 consists of two intersecting rectangular nanoblocks 13 arranged in a cross shape, with a nanocylinder 14 nested at the intersection of the two rectangular nanoblocks 13. The liquid crystal polarization control module 1 continuously adjusts the polarization state of the light, thereby adjusting the filtering ratio of green and blue light. The micro / nano metasurface unit 12 filters blue and green light respectively in mutually perpendicular polarization directions. Because different wavelengths of light have different attenuation rates in an underwater environment, red light has a longer wavelength and the weakest penetration ability, typically disappearing first at a depth of 3-4 meters underwater. Blue and green light have shorter wavelengths and travel further in water. Due to the most severe attenuation of the red component, the red component in underwater images is minimal; while the information in the blue and green channels is relatively well preserved. This embodiment of the invention effectively adjusts the transmittance of blue and green light, increasing the brightness or saturation of the blue and green channels to compensate for the lack of red light in the underwater environment, thus more effectively improving image color distortion and enhancing color reproduction.

[0080] The embodiments of the present invention utilize a metasurface array 2 to biomimeticize the compound eyes of insects, which can effectively filter the light of the desired color and further improve the problem of image color distortion.

[0081] In summary, the embodiments of the present invention no longer rely solely on image processing technology, but rather improve underwater imaging quality and enhance underwater color by utilizing the polarization sensitivity of metasurfaces and the optical rotation characteristics of liquid crystals, while ensuring real-time observation.

[0082] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0083] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0084] The above are merely preferred embodiments of the present invention and are 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 are included within the scope of protection of the present invention.

Claims

1. A biomimetic water-based color reproduction system based on a metasurface controlled by liquid crystal, characterized in that, The biomimetic water-based color reproduction system includes: a liquid crystal polarization light control module, a metasurface array, a power supply module, a polarization switch module, a transparent display module, and a water-based imaging module; The liquid crystal polarization light control module is used to adjust the polarization state of the incident light in order to change the filtering ratio of different colors of light. The metasurface array is used to filter incident light after passing through the liquid crystal polarization light modulation module by means of its polarization sensitivity, and to change the transmission spectrum of the filtered light; wherein, the number of micro-nano metasurface units in the metasurface array is M×N, where M and N are both natural numbers greater than or equal to 2. The power module is used to supply power to the biomimetic water-based color reproduction system; The polarization switch module is used to control the liquid crystal polarization light modulation module; The transparent display module is used to display detection information in real time, including underwater depth and distance; The water-based imaging module is used to perform underwater imaging based on the filtered light from the metasurface array. The biomimetic wading color restoration system is configured as follows: in response to an underwater imaging signal, the liquid crystal polarization light control module performs polarization filtering on the natural light entering the biomimetic wading color restoration system to obtain initial incident polarized light; the liquid crystal polarization light control module adjusts the polarization state of the initial incident polarized light by controlling the deflection of the liquid crystal therein to change the filtering ratio of different colors of light to obtain adjusted polarized light; the metasurface array filters the adjusted polarized light to obtain the desired polarized light; and the wading imaging module performs underwater imaging based on the desired polarized light. The metasurface array includes a substrate and a micro / nano grating array; the substrate is made of a material with a refractive index of 1-2; the micro / nano grating array is made of a material with a refractive index of 2-4; the micro / nano grating array is composed of multiple micro / nano grating units, each of which is a micro / nano metasurface unit, and the gaps between the arrays of micro / nano grating units are filled with a material whose refractive index is between that of the substrate material and the grating array; the structure of each micro / nano grating unit is two intersecting rectangular nanoblocks, which intersect to form a cross shape, and a nanocylinder is nested at the intersection of the two rectangular nanoblocks; The period of the micro-nano metasurface unit is 100nm-500nm, the length and width of the micro-nano metasurface unit are 30nm-450nm, the radius of the nanocylinder is 30nm-450nm, and the height of the micro-nano metasurface unit is 50nm-450nm.

2. The biomimetic water-based color reproduction system based on a liquid crystal-controlled metasurface according to claim 1, characterized in that, The liquid crystal polarization light control module continuously adjusts the polarization state of the light, thereby adjusting the filtering ratio of green and blue light; the micro-nano metasurface unit filters blue and green light respectively in mutually perpendicular polarization directions.

3. The biomimetic water-based color reproduction system based on a liquid crystal-controlled metasurface according to claim 1, characterized in that, The liquid crystal polarization light control module includes a polarizer, a light alignment layer, a liquid crystal molecule layer, and a transparent electrode; the transparent electrode has two arrangement methods: one is distributed on the side of the liquid crystal molecule layer, and the other is distributed on the front of the liquid crystal molecule layer.

4. The biomimetic water-based color reproduction system based on a metasurface controlled by liquid crystal as described in claim 1, characterized in that, The process of obtaining the period, length, width, and height of the micro / nano metasurface unit includes: The spectral response curves of materials corresponding to micro-nano metasurfaces with different lengths, widths, periods, and heights were simulated using the RCWA algorithm to construct the first dataset; A GAN network architecture is constructed, and the relationship between the material structure and the spectral response curve of the micro-nano metasurface is learned using the first dataset to train and obtain the GAN network model. Based on the spectrum of the target filtered light corresponding to the micro / nano metasurface unit, the period, length, width, and height of the micro / nano metasurface unit are obtained using the GAN network model.

5. The biomimetic water-based color reproduction system based on a metasurface controlled by liquid crystal as described in claim 1, characterized in that, The optimization process for the period, length, width, and height of the micro / nano metasurface unit includes: The average transmittance for wavelengths from 400 nm to 490 nm is calculated as blue light transmittance t1, with a standard deviation a1; the average transmittance for wavelengths from 491 nm to 570 nm is calculated as green light transmittance t2, with a standard deviation a2; and the average transmittance for wavelengths from 571 nm to 700 nm is calculated as red light transmittance t3, with a standard deviation a3. The standard deviation is used to describe the dispersion of transmittance measurements within the same set of wavelengths. By using a gradient descent-based reinforcement learning algorithm, the errors of t1, t2, t3 and the required transmittance are reduced during the process of iteratively optimizing the length, width, period, and height of the micro-nano metasurface unit. At the same time, the standard deviations a1, a2, a3 are constrained to be at a low level, thereby increasing the smoothness of the optimized micro-nano metasurface unit.

6. The biomimetic water-based color reproduction system based on a liquid crystal-controlled metasurface according to claim 1, characterized in that, The transparent display module includes a transparent electrode, a transparent monochrome LED, and a super lens.

7. The biomimetic water-based color reproduction system based on a liquid crystal-controlled metasurface according to claim 1, characterized in that, The metasurface array can be configured in various ways, including embedding a frame into the biomimetic water-based color reproduction system, embedding a lens into the biomimetic water-based color reproduction system, attaching a lens to the biomimetic water-based color reproduction system, or growing it directly on the lens of the biomimetic water-based color reproduction system.

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