Liquid crystal optical phased array imaging system and design method thereof

Abstract

The invention provides a liquid crystal optical phased array imaging system and a design method thereof, and belongs to the technical field of liquid crystal optical phased arrays. The system comprises a camera, a lens, a beam splitter prism, a liquid crystal spatial light modulator, a super lens and a computer, and is suitable for a visible light band. Non-mechanical light beam deflection is achieved through the liquid crystal spatial light modulator, angle amplification and dispersion compensation functions are achieved in combination with the super lens, and the problems that a traditional mechanical light beam deflection technology is large in size and short in service life are solved, and the problems that an existing liquid crystal optical phased array is small in angle range and imaging aliasing is caused by dispersion are solved; the superlens adopts a three-layer nanostructure unit stacking design, the upper layer is a dispersion compensation structure, the lower layer is an angle amplification structure, and large-angle imaging and efficient spectrum utilization are realized through phase modulation; the invention has the advantages of compact structure, small volume, low cost, high stability and the like, and is suitable for the fields of laser radar, space optical communication, infrared tracking and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid crystal optical phased arrays, and relates to a liquid crystal optical phased array imaging system and a design method thereof. Background Technique

[0002] Traditional imaging technology uses lenses or lens groups to form an optical system to achieve imaging of the observed scene. Early long-distance optical imaging means were mainly optical telescopes, and their angular resolution was limited by the diffraction limit. As the aperture of the telescope increases, its angular resolution will also be improved; as the detection distance increases, its spatial resolution decreases. Therefore, for high-resolution, real-aperture imaging of distant targets, a large-aperture telescope is required. Traditional imaging technology has the advantages of simple structure and excellent imaging quality, but at the same time, it also has disadvantages such as the increase in lens thickness with the increase in aperture size, expensive non-visible light lenses, the need for precise assembly, and low production efficiency. As the aperture of the telescope becomes larger and the overall becomes more complex, this undoubtedly increases the manufacturing difficulty and cost of the system.

[0003] In order to collect object information from all directions, it is difficult to achieve this with only one imaging system. Using multiple imaging systems will occupy more volume and cost more. Therefore, people have proposed a scanning method to achieve a larger imaging range. This method of beam angle scanning is also called beam deflection technology. Beam deflection technology refers to controlling the beam to perform precise dynamic pointing within a certain airspace, and has advantages such as flexibility and precision, and has a wide range of application backgrounds in many fields such as lidar, free-space optical communication, and biomedicine. Beam deflection is an important technical link for realizing target search, aiming, tracking, capture, and imaging. Traditional beam deflection technology mainly relies on mechanical rotating devices to change the direction of the optical axis to achieve beam pointing control. The mechanical beam control scheme has been very mature after long-term research and development, but its system has a large volume and weight, and at the same time, it also has many disadvantages such as short lifespan and large inertia, and it is difficult to meet the requirements of miniaturization, flexibility, and high efficiency of the scanning imaging application system. Non-mechanical beam deflection does not require applying mechanical force to drive a large mirror system, so there is no mechanical inertia and wear, and it has greater advantages in realizing agile rapid orientation, random scanning, and system miniaturization and integration.

[0004] Optical phased arrays are the mainstream solution for non-mechanical beam control technologies, and their core principle is basically similar to that of microwave phased arrays. Based on the principle of optical phase modulation, by controlling thousands of independent phase-shifting units, a spatially varying near-field phase distribution is achieved, and in the far field, the beam is reshaped in a coherent form, thus completing non-mechanical, fast, and high-precision beam pointing and scanning. Therefore, non-mechanical beam control systems based on optical phased arrays are more conducive to miniaturization and integration, and have the advantages of small size, light weight, and low power consumption. These advantages have prompted extensive research on optical phased array technologies, including electro-optic crystals, optical waveguides, nanophotonic integration, multiple quantum wells, microelectromechanical systems, and liquid crystal optical phased arrays, etc.

[0005] Liquid crystal optical phased arrays are one of the important solutions in non-mechanical beam pointing technologies. Liquid crystal phased arrays are phased modulation devices that use liquid crystals as the phase modulation material and are combined with an electrically controlled programmable electrode array. Each electrode and the liquid crystal in the area it controls form a controllable unit. When different driving voltages are applied to each controllable unit, the director of the liquid crystal molecules will deflect to different degrees, which in turn affects the effective refractive index of the liquid crystal molecules, achieving phase modulation of the light beam of the device, changing the outgoing direction of the light beam, and generating far-field interference in the specified direction to achieve beam deflection. It has the advantages of a compact structure, small size, light weight, and low driving voltage. It can not only improve the resolution of laser beam pointing and the accurate spatial scanning angle, but also provide precise, stable, fast, and agile beam deflection and beam shaping. It has important research and application value in fields such as lidar, free-space optical communication, and infrared tracking.

[0006] Classified from the perspective of system optical path design, liquid crystal optical phased arrays are divided into on-chip phased arrays and spatial light phased arrays. On-chip optical phased arrays integrate liquid crystal materials in in-plane silicon photon channels and use them as the phase-shifting region medium to modulate the in-chip laser. Due to its complex device design and high manufacturing cost, only small-area functional devices can be realized, and it is currently mostly used in the augmented reality / virtual reality (AR / VR) field. Spatial optical phased arrays are further divided into reflective and transmissive liquid crystal optical phased arrays. Reflective liquid crystal optical phased arrays often adopt a silicon substrate integration method, which can achieve pixel-level resolution and a relatively fast beam switching time, but the construction of the system optical path is relatively complex, and the deflection angle is small, which cannot meet the angle requirements of laser communication and is often used in fields such as vector beam generation and holographic display. Transmissive liquid crystal optical phased arrays encapsulate liquid crystal materials between a transparent substrate and a transparent conductive film to perform spatial phase modulation on the transmitted wavefront of the laser, causing it to deflect. Transmissive liquid crystal optical phased arrays can be adapted to the laser system with a plug-and-play structure and are an effective means for beam pointing devices in current laser communication systems.

[0007] In the fourth chapter of the prior art document "Research on Liquid Crystal Optical Phased Array Devices and Wave Control Methods", University of Electronic Science and Technology of China, Wu Liang: From the perspective of the application of liquid crystal optical phased arrays in laser phased communication, the phased access characteristics of liquid crystal optical phased arrays were studied. The phased access mechanism of liquid crystal optical phased arrays and the process of phase modulation were elaborated in detail. The receiving angle, control angle, and arrival angle in the phased access process and the angle relationship among the three were revealed. In the literature, the angle transformation range of the liquid crystal optical phased array is small, only ±1.2°. This system uses a single-wavelength laser as a light source for illumination and then collects the reflected light, belonging to the category of active detection. The system complexity is high and the light source stability is required to be highly stable; at the same time, the wavelength band is single, and the loss of light transmission back and forth is large, so the light energy that can be collected is less. In the fourth chapter of the document "Research on Key Technologies of Liquid Crystal Optical Phased Arrays", University of Electronic Science and Technology of China, Xiao Feng: An angle amplification method for liquid crystal optical phased arrays based on an inverted telescope was proposed, and a coarse-scanning - fine-scanning cascade structure based on this method was designed to achieve quasi-continuous scanning of liquid crystal optical phased arrays in a large angle range, and the angle amplification factor reached 3.5 times. However, this work uses a spatial lens and two liquid crystal optical phased arrays. The use of the spatial lens increases the instability of the system, and the second liquid crystal optical phased array increases the cost complexity of the system. Summary of the Invention

[0008] The technical solution of the present invention is used to solve the problems of large volume and short lifespan of traditional mechanical beam deflection technology, as well as small angle range and imaging aliasing caused by dispersion of existing liquid crystal optical phased arrays.

[0009] The present invention solves the above technical problems through the following technical solutions: The present invention provides a liquid crystal optical phased array imaging system for the visible light band, including: a camera, a lens, a beam splitter prism, a liquid crystal spatial light modulator, a metasurface lens, and a computer; the camera, the liquid crystal spatial light modulator, and the computer are connected by cables. The camera is used to collect image information and display it on the computer. The lens is arranged in front of the camera lens, and the optical axis of the camera is coaxial with the optical axis of the lens. The lens is used to converge the light transmitted from the beam splitter prism onto the target surface of the camera. The beam splitter prism is arranged between the liquid crystal spatial light modulator and the metasurface lens. The horizontal optical axis of the beam splitter prism is coaxial with the optical axes of the liquid crystal spatial light modulator and the metasurface lens, and the vertical optical axis of the beam splitter prism is coaxial with the optical axis of the lens.

[0010] Furthermore, the white light emitted from a certain point of the analyte passes through the metalens, and the metalens realizes the functions of angle magnification and dispersion compensation. The light transmitted by the metalens passes through the beam splitter prism and reaches the liquid crystal spatial light modulator. The light reflected by the liquid crystal spatial light modulator undergoes a 90° angular deflection through the beam splitter prism and reaches the lens. The camera captures the image information and displays it on the computer. By changing the applied voltage signal on the computer, the phase difference between the liquid crystal cells of the liquid crystal spatial light modulator is changed, thereby changing the angle of the light beam emitted therefrom.

[0011] Furthermore, the method for the metalens to realize the angle magnification function is as follows: The light of a single wavelength emitted from a certain point of the analyte is incident on the metalens at an angle of θ1 degrees, and the light output by the metalens irradiates the beam splitter prism at an angle of θ1 / N, where N is the magnification factor.

[0012] Furthermore, the method for the metalens to realize the dispersion compensation function is as follows: The white light emitted from a certain point of the analyte is incident on the metalens at an angle of θ2 degrees. The output light angle of the metalens is centered on θ2 and forms an angle range [θ2 / N - δθ, θ2 / N + δθ], where δθ is the angle difference between the monochromatic light with the longest wavelength and the monochromatic light with the shortest wavelength in the white light; it irradiates the liquid crystal spatial light modulator through the beam splitter prism. While the liquid crystal spatial light modulator deflects the incident light angle, the dispersion inside the liquid crystal spatial light modulator is canceled, and the output angles of the light of each wavelength are kept consistent. Then, it passes through the beam splitter prism and the lens and converges to the same position on the camera target surface for imaging.

[0013] Furthermore, the metalens is a stacked structure of three-layer nanostructure units. The top layer is the dispersion compensation structure, and the following two layers are the angle magnification structures; the dispersion compensation structure is formed by arranging multiple nanostructure units on the silica layer; the angle magnification structure includes: a convex lens layer and a concave lens layer, and both the convex lens layer and the concave lens layer are formed by arranging multiple nanostructure units on the silica layer.

[0014] Furthermore, the design method of the metalens is as follows: Step 1: Scan the effective refractive index n corresponding to different nanostructure units through the FDTD optical simulation software eff , and establish a mapping relationship database between the phase of the nanostructure unit and the effective refractive index n eff ; The mapping relationship between the phase of the nanostructure unit and the effective refractive index is as follows: (1) where is the phase of the nanostructure unit at each position of the metalens, λ is the wavelength of the incident light, and n effis the effective refractive index of each nanostructure unit, and h is the height of each nanostructure unit; Step 2: Select nanostructure units from the database according to formula (4) and arrange them at corresponding positions of the metalens to cancel out the phase distribution introduced by the metalens, achieving the purpose of phase difference compensation; (4) where is the distribution of the phase of light at each wavelength after phase difference compensation with respect to the coordinate position x, and b is the phase difference adjustment constant; Step 3: The wavefront phase distributions of the convex lens layer and the concave lens layer in the angular magnification structure of the metalens are as follows: (5) (6) where f1 and f2 are the focal lengths of the convex lens layer and the concave lens layer respectively, and are the phase correction values of the wavefront phase distributions of the convex lens layer and the concave lens layer; Adjust the focal lengths f1 and f2 according to formulas (5) and (6) so that when the focal positions of the convex lens layer and the concave lens layer coincide, then select nanostructure units from the database and arrange them at corresponding positions of the metalens to complete the design of the angular magnification structure.

[0015] Further, the camera is a CCD camera, the single-frame acquisition time is greater than the response time of the liquid crystal spatial light modulator, and the target surface covers the imaging field of view.

[0016] Further, the beam splitter prism is a depolarization beam splitter prism.

[0017] Further, the liquid crystal spatial light modulator is a reflective phase modulation type device.

[0018] Further, the metalens is fabricated using CMOS technology, and the metalens is transmissive or reflective.

[0019] The beneficial effects of the present invention are as follows: 1) Using a liquid crystal spatial light modulator as an optical phased array, the scanning of the detection direction is realized through voltage control, avoiding mechanical scanning and achieving imaging in different directions; 2) Without using a laser as a light source, natural light can be used as a light source, simplifying the system and reducing costs; 3) Using a metalens expands the imaging field of view, compensates for chromatic dispersion, and natural light imaging will not cause image aliasing on the camera, improving the spectral utilization rate; 4) Realizing the angular magnification function through the metalens, eliminating the spatial lens group, simplifying the system, and improving the system stability; 5) The dispersion compensation function is achieved through a metalens, making full use of multiple wavelengths of natural light, improving the spectral utilization rate of the system, enhancing the energy detected by the camera, and thus improving the signal-to-noise ratio. Description of the Drawings

[0020] Figure 1 is a structural diagram of the liquid crystal optical phased array imaging system according to an embodiment of the present invention; Figure 2 is a structural diagram of the metalens according to an embodiment of the present invention; Figure 3 is a schematic diagram of the angular magnification principle of the metalens according to an embodiment of the present invention; Figure 4 is a schematic diagram of the dispersion compensation principle of the metalens according to an embodiment of the present invention; Figure 5 is a schematic diagram of different nanostructure units according to an embodiment of the present invention; Figure 6 is a phase distribution diagram of red, green, and blue lights with different wavelengths varying with coordinates before passing through the nanostructure unit according to an embodiment of the present invention; Figure 7 is a distribution diagram of the phase of light of each wavelength varying with position x after the phase difference compensation of red, green, and blue lights according to an embodiment of the present invention; Figure 8 is a phase distribution diagram of red, green, and blue lights with different wavelengths varying with coordinates after passing through the nanostructure unit according to an embodiment of the present invention; Figure 9 is an angular magnification device based on a lens group in the prior art. Detailed Embodiments

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, rather than all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings of the specification and specific embodiments: Embodiment 1 As Figure 1As shown in the figure, the liquid crystal optical phased array imaging system with angular magnification and dispersion compensation function in this embodiment is composed of a camera 10, a lens 11, a beam splitter prism 12, a liquid crystal spatial light modulator 13, a meta-lens 14, and a computer 15, and acts in the visible light band; the dotted line in the figure is the optical axis, that is, the light propagation path, and the solid line is the cable, which is used for the connection between the camera 10, the liquid crystal spatial light modulator 13 and the computer 15. The computer 15 can send instructions to the camera 10 and the liquid crystal spatial light modulator 13 at the same time, and receive the image information collected by the camera 10.

[0023] The camera 10 is a CCD camera, and the single-frame acquisition time is longer than the response time of the liquid crystal spatial light modulator 13. The target surface covers the imaging field of view, and is used to collect image information and display it on the computer 15. The light within the field of view of the lens 11 can be converged onto the target surface of the camera 10, and the light outside the field of view will not be detected.

[0024] The lens 11 is a convex lens, which is arranged in front of the lens of the camera 10. The optical axis of the camera 10 is coaxial with the optical axis of the lens 11. The lens 11 is used to converge the light transmitted from the beam splitter prism 12 onto the target surface of the camera 10.

[0025] The beam splitter prism 12 is a depolarization-free beam splitter prism, which is arranged between the liquid crystal spatial light modulator 13 and the meta-lens 14. The horizontal optical axis of the beam splitter prism 12 is coaxial with the optical axes of the liquid crystal spatial light modulator 13 and the meta-lens 14, and the vertical optical axis of the beam splitter prism 12 is coaxial with the optical axis of the lens 11. The light transmitted from the meta-lens 14 passes through the beam splitter prism 12 and reaches the liquid crystal spatial light modulator 13. The light reflected back by the liquid crystal spatial light modulator 13 undergoes a 90° angular deflection through the beam splitter prism 12 and reaches the lens 11.

[0026] The liquid crystal spatial light modulator 13 is a reflective phase modulation type device, which receives the incident light from the beam splitter prism 12 and reflects it back to the beam splitter prism 12. By changing the applied voltage signal, the phase difference between the liquid crystal cells of the liquid crystal spatial light modulator 13 is changed, thereby changing the angle of the light beam emitted.

[0027] As Figure 2 As shown in the figure, the meta-lens 14 is a stacked structure of three-layer nano-structured units. The top layer is a dispersion compensation structure 141, and the following two layers are angular magnification structures 142; the dispersion compensation structure 141 is formed by arranging a plurality of nano-structured units 1411 on a silica layer; the angular magnification structure 142 includes: a convex lens layer and a concave lens layer, and both the convex lens layer and the concave lens layer are also formed by arranging a plurality of nano-structured units 1411 on a silica layer.

[0028] The dispersion compensation layer 141 is used to solve the problem that light of different wavelengths has different exit angles when transmitted in the liquid crystal spatial light modulator 13, and can make light of different wavelengths incident at the same angle have the same exit angle; the angle magnification layer 142 is used to make the large-angle incident light exit at a small angle that satisfies the field of view of the camera 10, so as to be transmitted to the beam splitting prism 12.

[0029] Preferably, the metalens 14 is fabricated using CMOS technology. The metalens 14 can be transmissive or reflective, is a passive device, and the angle change magnification is a fixed value. A tuning structure can be added to make the change magnification adjustable.

[0030] The principles of angle magnification and dispersion compensation are as follows: Light of a single wavelength emitted from a certain point of the object to be measured is incident on the metalens at an angle of θ1. The light output by the metalens is irradiated on the beam splitting prism at an angle of θ1 / N, where N is the magnification factor, as Figure 3 shown. White light emitted from a certain point of the object to be measured is incident on the metalens at an angle of θ2. The exit angle of the light output by the metalens is centered on θ2, forming an angle range [θ2 / N - δθ, θ2 / N + δθ], where δθ is the angle difference between the monochromatic light with the longest wavelength and the monochromatic light with the shortest wavelength in the white light; after being irradiated on the liquid crystal spatial light modulator through the beam splitting prism, while the liquid crystal spatial light modulator deflects the incident light angle, the dispersion inside the liquid crystal spatial light modulator is cancelled out, and the exit angles of the exit light of each wavelength remain the same. Then, it passes through the beam splitting prism and the lens and converges to the same position on the camera target surface for imaging, as Figure 4 shown.

[0031] The design method of the metalens is as follows: 1. Establish a mapping relationship database between the phase of the nanostructure unit and the effective refractive index.

[0032] By using the FDTD (Finite-Difference Time-Domain) optical simulation software to scan the effective refractive index n corresponding to different nanostructure units eff , establish a mapping relationship database between the phase of the nanostructure unit and the effective refractive index n eff .

[0033] As Figure 5 shown, there are three different nanostructure units. The nanostructure units are randomly generated and are not limited to these three, and can be random permutations and combinations of multiple structures.

[0034] The mapping relationship between the phase of the nanostructure unit and the effective refractive index is as follows: (1) Among them, is the phase of the nanostructure unit at each position of the metalens, λ is the wavelength of the incident light, and n eff is the effective refractive index of each nanostructure unit, and h is the height of each nanostructure unit.

[0035] 2. Design the dispersion compensation structure The calculation formula for the exit angle of the incident light after passing through the metalens is as follows: (2) According to formula (2), at a certain exit angle θ, the relationship between the phase distribution of light with different wavelengths before passing through the nanostructure unit of the metalens and the incident position coordinate is as follows: (3) where θ is the exit angle of the incident light after passing through the metalens, is the phase distribution introduced by the metalens, and x is the incident position coordinate of the incident light.

[0036] It can be seen from formula (3) that at a certain exit angle θ, for light of a single wavelength, the phase distribution introduced by the metalens has a linear relationship with the incident position coordinate x of the incident light.

[0037] For example, the typical wavelengths of red, green, and blue lights are 450 nm, 532 nm, and 633 nm respectively. From formula (3), the linear relationship diagram between their phase distributions and the incident position coordinate x of the incident light is as shown in Figure 6 . It can be seen from Figure 6 that the phase difference between lights of different wavelengths changes with the change of the incident position coordinate x. For example, the phase difference between green light and blue light increases with the increase of x and is not a constant value. Therefore, phase difference compensation is required to make the phase difference between lights of different wavelengths a constant value.

[0038] As shown in Figure 7 , it is the linear change diagram of the phases of lights of different wavelengths after phase difference compensation with respect to the incident position coordinate x. Taking green light as an example, Figure 6 the linear slope in G is assumed to be k Figure 7 then the linear slope in G is -k. The change diagram of the phases of lights of different wavelengths with respect to the incident position coordinate x after phase difference compensation is as shown in Figure 8 . At this time, the phase difference between lights of different wavelengths is a constant value.

[0039] Therefore, it can be seen from formula (3) that the phase of the arranged nanostructure units needs to satisfy formula (4). The nanostructure units are selected from the database according to formula (4) and arranged at the corresponding positions of the superlens, so as to cancel the phase distribution introduced by the superlens and achieve the purpose of phase difference compensation.

[0040] (4) wherein, is the distribution of the phase of light at each wavelength after phase difference compensation with respect to the coordinate position x, and b is the phase difference adjustment constant.

[0041] 3. Design the angular magnification structure As Figure 9 shown, the traditional method uses an angular magnification device based on a lens group for angular magnification. The lens group is composed of a convex lens and a concave lens. The lens group is large in volume and easily damaged, which is not conducive to the integration and miniaturization of the imaging system.

[0042] Since angular magnification requires the use of the lens focusing function and both the convex lens and the concave lens have focal points, the present invention can use a superlens to replace the traditional lens group. The focal lengths of the convex lens and the concave lens are f1 and f2 respectively, and the magnification factor is N = -f1 / f2; therefore, it is necessary to design two layers of superlens structures with the functions of a convex lens and a concave lens respectively, and combine them up and down to generate an angular magnification function.

[0043] The phase modulation principle of the superlens structure is different from that of the traditional lens group structure. The superlens controls light waves through the abrupt phase shift of sub-wavelength micro-nano units to achieve the control of the beam direction. The wavefront phase distributions of the convex lens layer and the concave lens layer in the angular magnification structure of the superlens are as follows: (5) (6) wherein, f1 and f2 are the focal lengths of the convex lens layer and the concave lens layer respectively, and are the phase correction values of the wavefront phase distributions of the convex lens layer and the concave lens layer.

[0044] According to formulas (5) and (6), the focal lengths f1 and f2 are adjusted so that when the focal point positions of the convex lens layer and the concave lens layer coincide, the angular magnification function can be achieved. At this time, the nanostructure units are selected from the database and arranged at the corresponding positions of the superlens to complete the design of the angular magnification structure.

[0045] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid crystal optical phased array imaging system for the visible light band, characterized in that, Including: a camera (10), a lens (11), a beam splitter prism (12), a liquid crystal spatial light modulator (13), a metalens (14), and a computer (15); the camera (10), the liquid crystal spatial light modulator (13), and the computer (15) are connected by cables. The camera (10) is used to collect image information and display it on the computer (15). The lens (11) is disposed in front of the lens of the camera (10), and the optical axis of the camera (10) is coaxial with the optical axis of the lens (11). The lens (11) is used to converge the light transmitted from the beam splitter prism (12) onto the target surface of the camera (10). The beam splitter prism (12) is disposed between the liquid crystal spatial light modulator (13) and the metalens (14). The horizontal optical axis of the beam splitter prism (12) is coaxial with the optical axes of the liquid crystal spatial light modulator (13) and the metalens (14), and the vertical optical axis of the beam splitter prism (12) is coaxial with the optical axis of the lens (11).

2. The liquid crystal optical phased array imaging system according to claim 1, wherein The white light emitted from a certain point of the object to be measured passes through the metalens (14). The metalens (14) realizes the functions of angle magnification and chromatic dispersion compensation. The light transmitted by the metalens (14) passes through the beam splitter prism (12) and reaches the liquid crystal spatial light modulator (13). The light reflected by the liquid crystal spatial light modulator (13) undergoes a 90° angular deflection through the beam splitter prism (12) and reaches the lens (11). The camera (10) collects image information and displays it on the computer (15). By changing the applied voltage signal through the computer (15), the phase difference between the liquid crystal cells of the liquid crystal spatial light modulator (13) is changed, thereby changing the angle of the light beam emitted therefrom.

3. The liquid crystal optical phased array imaging system according to claim 1, wherein The method for the metalens (14) to realize the angle magnification function is as follows: The light of a single wavelength emitted from a certain point of the object to be measured is incident on the metalens (14) at an angle of θ1 degrees, and the light output by the metalens (14) is incident on the beam splitter prism (12) at an angle of θ1 / N, where N is the magnification factor.

4. The liquid crystal optical phased array imaging system according to claim 1, wherein The method for the metalens (14) to realize the chromatic dispersion compensation function is as follows: The white light emitted from a certain point of the object to be measured is incident on the metalens at an angle of θ2 degrees. The output light angle of the metalens is centered on θ2, forming an angle range [θ2 / N - δθ, θ2 / N + δθ], where δθ is the angle difference between the monochromatic light with the longest wavelength and the monochromatic light with the shortest wavelength in the white light; after passing through the beam splitter prism and irradiating the liquid crystal spatial light modulator, while the liquid crystal spatial light modulator deflects the incident light angle, the chromatic dispersion inside the liquid crystal spatial light modulator is canceled, and the output light angle of each wavelength remains the same. Then, it passes through the beam splitter prism and the lens and converges at the same position on the target surface of the camera for imaging.

5. The liquid crystal optical phased array imaging system according to claim 1, characterized in that, The superlens (14) is a stacked structure of three-layer nanostructure units. The top layer is a dispersion compensation structure (141), and the following two layers are angular magnification structures (142); the dispersion compensation structure (141) is formed by arranging multiple nanostructure units (1411) on a silica layer; the angular magnification structure (142) includes: a convex lens layer and a concave lens layer, and both the convex lens layer and the concave lens layer are formed by arranging multiple nanostructure units (1411) on a silica layer.

6. The liquid crystal optical phased array imaging system according to claim 5, wherein The design method of the superlens (14) is as follows: Step 1. Scan the effective refractive index n corresponding to different nanostructure units through FDTD optical simulation software eff to establish a mapping relationship database between the phase of the nanostructure unit and the effective refractive index n eff ; The mapping relationship between the phase of the nanostructure unit and the effective refractive index is as follows: （1） wherein, is the phase of the nanostructure unit at each position of the metalens, λ is the wavelength of the incident light, and n eff is the effective refractive index of each nanostructure unit, and h is the height of each nanostructure unit; Step 2: Select nanostructure units from the database according to formula (4) and arrange them at corresponding positions of the superlens, so as to cancel the phase distribution introduced by the superlens and achieve the purpose of phase difference compensation; （4） Among them, is the distribution of the phase of light at each wavelength after phase difference compensation with respect to the coordinate position x, and b is the phase difference adjustment constant; Step 3: The wavefront phase distributions of the convex lens layer and the concave lens layer in the angular magnification structure (142) of the superlens are as follows: （5） （6） where f1 and f2 are the focal lengths of the convex lens layer and the concave lens layer respectively, and the phase correction values of the wavefront phase distributions of the convex lens layer and the concave lens layer; Adjust the focal lengths f1 and f2 according to formulas (5) and (6) so that when the focal positions of the convex lens layer and the concave lens layer coincide, then select nanostructure units from the database and arrange them at corresponding positions of the superlens to complete the design of the angular magnification structure.

7. The liquid crystal optical phased array imaging system according to claim 1, wherein The camera (10) is a CCD camera, the single-frame acquisition time is greater than the response time of the liquid crystal spatial light modulator (13), and the target surface covers the imaging field of view.

8. The liquid crystal optical phased array imaging system according to claim 1, wherein The beam splitting prism (12) is a depolarization-free beam splitting prism.

9. The liquid crystal optical phased array imaging system according to claim 1, wherein, The liquid crystal spatial light modulator (13) is a reflective phase modulation type device.

10. The liquid crystal optical phased array imaging system according to claim 1, wherein The superlens (14) is fabricated using CMOS technology and can be transmissive or reflective.

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