Liquid crystal optical phased array imaging system and design method thereof

Abstract

The application 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 light splitting prism, a liquid crystal spatial light modulator, a superlens and a computer, and is suitable for a visible light waveband; non-mechanical beam deflection is realized through the liquid crystal spatial light modulator, angle amplification and dispersion compensation functions are realized in combination with the superlens, the problems of large volume and short service life of traditional mechanical beam deflection technology are solved, and the imaging aliasing problem caused by the small angle range of the existing liquid crystal optical phased array and dispersion is solved; the superlens adopts a three-layer nano structure unit stacking design, the upper layer is a dispersion compensation structure, and the lower layer is an angle amplification structure; through phase modulation, large-angle imaging and efficient utilization of the spectrum are realized; the application has the advantages of compact structure, small volume, low cost, high stability and the like, and is suitable for fields such as laser radar, space optical communication and infrared tracking.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystal optical phased array technology, and relates to a liquid crystal optical phased array imaging system and its design method. Background Technology

[0002] Traditional imaging techniques utilize lenses or lens groups to form an optical system, enabling the imaging of the observed scene. Early long-distance optical imaging methods primarily involved optical telescopes, whose angular resolution was limited by the diffraction limit. As the telescope aperture increases, its angular resolution improves; however, as the detection distance increases, its spatial resolution decreases. Therefore, high-resolution, real-aperture imaging of distant targets requires large-aperture telescopes. Traditional imaging techniques offer advantages such as simple structure and excellent image quality, but also suffer from drawbacks such as increased lens thickness with aperture size, high cost of non-visible lenses, the need for precision assembly, and low manufacturing efficiency. As telescope apertures become increasingly larger, the overall system becomes more complex, undoubtedly increasing the manufacturing difficulty and cost.

[0003] To collect information about objects from all directions, a single imaging system is insufficient, while multiple systems would require more space and incur higher costs. Therefore, scanning methods have been developed to achieve a wider imaging range; this beam angle scanning method is also known as beam deflection technology. Beam deflection technology refers to controlling the precise dynamic pointing of a beam within a specific spatial domain. It offers advantages such as agility and precision, and has wide applications in fields such as lidar, space optical communication, and biomedicine. Beam deflection is a crucial technical step in achieving target search, aiming, tracking, acquisition, and imaging. Traditional beam deflection technology primarily relies on mechanical rotating devices to change the direction of the optical axis to control beam pointing. While mechanical beam control schemes have matured through long-term research and development, they suffer from large system size and weight, short lifespan, and high inertia, making it difficult to meet the miniaturization, flexibility, and high efficiency requirements of scanning imaging applications. Non-mechanical beam deflection, on the other hand, does not require mechanical force to drive a large mirror system, thus eliminating mechanical inertia and wear. It offers significant advantages in achieving agile, rapid orientation, random scanning, and miniaturized system integration.

[0004] Optical phased arrays are the mainstream solution for non-mechanical beam control technology, and their core principle is basically similar to that of microwave phased arrays. Based on the principle of light phase modulation, they achieve spatially varying near-field phase distribution by controlling thousands of independent phase-shifting units, and coherently reshape the beam in the far field, thus achieving 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, offering advantages such as small size, light weight, and low power consumption. These advantages have spurred extensive research into optical phased array technology, including electro-optic crystals, optical waveguides, nanophotonic integration, multiple quantum wells, microelectromechanical systems (MEMS), and liquid crystal optical phased arrays.

[0005] Liquid crystal phased arrays (LCDs) are a crucial solution in non-mechanical beam pointing technology. An LCD uses liquid crystal as the phase modulation material, combined with an electronically programmable electrode array, forming a phase-controlled modulation device. Each electrode and the liquid crystal in its controlled region constitute a controllable unit. Applying different driving voltages to each controllable unit causes varying degrees of deflection of the liquid crystal molecules' pointing vectors, thus affecting the effective refractive index of the liquid crystal molecules. This achieves phase modulation of the beam emitted by the device, altering the beam's exit direction and generating far-field interference in a specified direction, thereby achieving beam deflection. LCDs offer advantages such as compact structure, small size, light weight, and low driving voltage. They not only improve the resolution of laser beam pointing and precise spatial scanning angles but also provide accurate, stable, and rapidly variable beam deflection and beam shaping. They have significant research and application value in fields such as lidar, space optical communication, and infrared tracking.

[0006] From the perspective of system optical path design, liquid crystal optical phased arrays are classified into on-chip phased arrays and spatial optical phased arrays. On-chip optical phased arrays integrate liquid crystal material into an in-plane silicon photonic channel, using it as a phase-shifting medium to modulate the on-chip laser. Due to its complex device design and high manufacturing cost, it can only realize small-area functional devices and is currently mostly used in augmented reality / virtual reality (AR / VR) fields. Spatial optical phased arrays are further divided into reflective and transmissive liquid crystal optical phased arrays. Reflective liquid crystal optical phased arrays often use silicon substrate integration, achieving pixel-level resolution and fast beam switching time, but the system optical path construction is more complex, and the deflection angle is smaller, which cannot meet the angle requirements of laser communication. They are often used in vector beam generation and holographic displays. Transmissive liquid crystal optical phased arrays encapsulate liquid crystal material between a transparent substrate and a transparent conductive film, spatially modulating the transmitted wavefront of the laser to cause deflection. Transmissive liquid crystal optical phased arrays can be adapted to laser systems using a pluggable structure and are currently an effective means of beam pointing in laser communication systems.

[0007] The existing literature, "Research on Liquid Crystal Optical Phased Array Devices and Wavelength Control Methods," by Wu Liang of the University of Electronic Science and Technology of China, studies the phased access characteristics of liquid crystal optical phased arrays from the perspective of their application in laser phased communication. It elaborates on the phased access mechanism and phase modulation process of liquid crystal optical phased arrays, revealing the issues of the receiving angle, control angle, and arrival angle, as well as the angular relationships among them. The angle transformation range of the liquid crystal optical phased array in this paper is relatively small, only ±1.2°. This system uses a single-wavelength laser as the light source for illumination and then collects the reflected light, falling under the category of active detection. The system is complex and requires high stability of the light source; simultaneously, the single wavelength results in significant light transmission loss, thus limiting the amount of light energy that can be collected. Chapter 4 of the paper "Research on Key Technologies of Liquid Crystal Optical Phased Arrays" by Xiao Feng of the University of Electronic Science and Technology of China proposes an angle magnification method for liquid crystal optical phased arrays based on an inverted telescope. A coarse-fine scan cascaded structure based on this method is designed to achieve quasi-continuous scanning of the liquid crystal optical phased array over a large angle range, achieving an angle magnification of 3.5 times. However, this work employs a spatial lens and two liquid crystal optical phased arrays. The use of the spatial lens increases the system's instability, and the second liquid crystal optical phased array increases the system's cost and complexity. Summary of the Invention

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

[0009] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0010] This invention provides a liquid crystal optical phased array imaging system for the visible light band, comprising: a camera, a lens, a beam splitter, a liquid crystal spatial light modulator, a superlens, and a computer; the camera, the liquid crystal spatial light modulator, and the computer are connected by cables; the camera is used to acquire image information and display it on the computer; the lens is disposed 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 onto the target surface of the camera; the beam splitter is disposed between the liquid crystal spatial light modulator and the superlens; the horizontal optical axis of the beam splitter is coaxial with the optical axes of the liquid crystal spatial light modulator and the superlens, and the vertical optical axis of the beam splitter is coaxial with the optical axis of the lens.

[0011] Furthermore, the white light emitted from a point on the object under test passes through a superlens, which amplifies the angle and compensates for dispersion. The light transmitted through the superlens is then transmitted through a beam splitter and reaches the liquid crystal spatial light modulator. The light reflected back from the liquid crystal spatial light modulator is deflected by 90° by the beam splitter and reaches the lens. The camera acquires image information and displays it on the computer. The computer changes the applied voltage signal to change the phase difference between the liquid crystal cells of the liquid crystal spatial light modulator, thereby changing the angle of the emitted beam.

[0012] Furthermore, the method for achieving angle magnification using a superlens is as follows: a single wavelength of light emitted from a point on the object under test is incident on the superlens at an angle θ1 degrees, and the light output from the superlens is incident on the beam splitter at an angle θ1 / N, where N is the magnification.

[0013] Furthermore, the method for achieving dispersion compensation using a superlens is as follows: White light emitted from a point on the object under test is incident on the superlens at an angle of θ2 degrees. The angle of the outgoing light from the superlens is centered on θ2, forming an angle range [θ2 / N-δθ, θ2 / N+δθ], where δθ is the angle difference between the longest wavelength monochromatic light and the shortest wavelength monochromatic light in the white light. After passing through a beam splitter, the light is incident on a liquid crystal spatial light modulator. While the liquid crystal spatial light modulator deflects the angle of the incident light, the dispersion inside the liquid crystal spatial light modulator is canceled out, and the outgoing angle of each wavelength of outgoing light remains consistent. Then, after passing through a beam splitter and a lens, the light is converged to the same position on the camera target surface for imaging.

[0014] Furthermore, the superlens is a three-layer stacked nanostructure unit structure, with the top layer being a dispersion compensation structure and the bottom two layers being angle magnification structures; the dispersion compensation structure is formed by arranging multiple nanostructure units on a silicon dioxide layer; the angle magnification structure includes a convex lens layer and a concave lens layer, both of which are formed by arranging multiple nanostructure units on a silicon dioxide layer.

[0015] Furthermore, the design method of the superlens is as follows:

[0016] Step 1: Scan the effective refractive index n corresponding to different nanostructure units using FDTD optical simulation software. eff Establish the phase and effective refractive index n of the nanostructure unit. eff The mapping relationship database between them;

[0017] The mapping relationship between the phase and effective refractive index of the aforementioned nanostructure unit is as follows:

[0018] (1)

[0019] in, Let n be the phase of the nanostructure unit at each position of the superlens, λ be the wavelength of the incident light, and n be the phase of the nanostructure unit at each position of the superlens. eff The effective refractive index of each nanostructure unit, h is the height of each nanostructure unit;

[0020] Step 2: Select nanostructure units from the database according to formula (4) and arrange them at the corresponding positions of the superlens to offset the phase distribution introduced by the superlens and achieve the purpose of phase difference compensation.

[0021] (4)

[0022] in, Let be the phase distribution of light at each wavelength after phase difference compensation as a function of coordinate position x, and b be the phase difference adjustment constant.

[0023] Step 3: The wavefront phase distributions of the convex and concave lens layers in the superlens's angle magnification structure are as follows:

[0024] (5)

[0025] (6)

[0026] Where f1 and f2 are the focal lengths of the convex lens layer and the concave lens layer, respectively. and Phase correction values ​​for the wavefront phase distribution of the convex and concave lens layers;

[0027] Adjust the focal lengths f1 and f2 according to formulas (5) and (6) so that 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 the corresponding positions of the superlens to complete the design of the angle magnification structure.

[0028] Furthermore, the camera is a CCD camera, with a single-frame acquisition time greater than the response time of the liquid crystal spatial light modulator, and the target surface covers the imaging field of view.

[0029] Furthermore, the beam splitter is a depolarizing beam splitter.

[0030] Furthermore, the liquid crystal spatial light modulator is a reflective phase modulation device.

[0031] Furthermore, the superlens is fabricated using CMOS technology and is either transmissive or reflective.

[0032] The beneficial effects of this invention are as follows:

[0033] 1) A liquid crystal spatial light modulator is used as an optical phased array, and scanning of the detection direction is achieved through voltage control, avoiding mechanical scanning and realizing imaging in different directions;

[0034] 2) No laser is needed as a light source; natural light can be used, simplifying the system and reducing costs.

[0035] 3) The use of superlenses expands the imaging field of view, compensates for dispersion, and prevents image aliasing on the camera when imaging with natural light, thus improving the utilization of the spectrum.

[0036] 4) The angle magnification function is achieved through a superlens, eliminating the need for a spatial lens group, simplifying the system, and improving system stability;

[0037] 5) By using a superlens to achieve dispersion compensation, multiple wavelengths of natural light are fully utilized, improving the spectral utilization of the system and increasing the energy detected by the camera, thereby improving the signal-to-noise ratio. Attached Figure Description

[0038] Figure 1 This is a structural diagram of the liquid crystal optical phased array imaging system according to an embodiment of the present invention;

[0039] Figure 2 This is a structural diagram of the superlens according to an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram illustrating the principle of angle magnification using a superlens according to an embodiment of the present invention;

[0041] Figure 4 This is a schematic diagram illustrating the dispersion compensation principle of the superlens according to an embodiment of the present invention.

[0042] Figure 5 These are schematic diagrams of different nanostructure units in embodiments of the present invention;

[0043] Figure 6 This is a phase distribution diagram of red, green and blue light at different wavelengths as a function of coordinates before passing through the nanostructure unit in an embodiment of the present invention;

[0044] Figure 7 This is a distribution diagram of the phase distribution of each wavelength of light after phase difference compensation for red, green and blue light in an embodiment of the present invention as a function of position x;

[0045] Figure 8 This is a phase distribution diagram of red, green, and blue light at different wavelengths as a function of coordinates after passing through a nanostructure unit in an embodiment of the present invention.

[0046] Figure 9 It is an existing technology based on lens group angle magnification device. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of 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 only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0049] Example 1

[0050] like Figure 1 As shown, the liquid crystal optical phased array imaging system with angular magnification and dispersion compensation function in this embodiment consists of a camera 10, a lens 11, a beam splitter 12, a liquid crystal spatial light modulator 13, a superlens 14, and a computer 15, and operates in the visible light band. The dashed 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 commands 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.

[0051] The camera 10 is a CCD camera, with a single frame acquisition time greater 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 acquire image information and display it on the computer 15. Light within the field of view of the lens 11 can be focused onto the target surface of the camera 10, while light outside the field of view will not be detected.

[0052] The lens 11 is a convex lens and is positioned 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 12 onto the target surface of the camera 10.

[0053] The beam splitter 12 is a depolarizing beam splitter 13, which is disposed between the liquid crystal spatial light modulator 13 and the superlens 14. The horizontal optical axis of the beam splitter 12 is coaxial with the optical axes of the liquid crystal spatial light modulator 13 and the superlens 14, and the vertical optical axis of the beam splitter 12 is coaxial with the optical axis of the lens 11. The light transmitted from the superlens 14 is transmitted through the beam splitter 12 and reaches the liquid crystal spatial light modulator 13. The light reflected back from the liquid crystal spatial light modulator 13 is deflected by 90° through the beam splitter 12 and reaches the lens 11.

[0054] The liquid crystal spatial light modulator 13 is a reflective phase modulation device that receives incident light from the beam splitter 12 and reflects it back to the beam splitter 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 its beam emission.

[0055] like Figure 2 As shown, the superlens 14 is a three-layer stacked nanostructure unit structure, with the top layer being a dispersion compensation structure 141 and the bottom two layers being angle magnification structures 142. The dispersion compensation structure 141 is formed by arranging multiple nanostructure units 1411 on a silicon dioxide layer. The angle magnification structure 142 includes a convex lens layer and a concave lens layer, both of which are also formed by arranging multiple nanostructure units 1411 on a silicon dioxide layer.

[0056] 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, so that light of different wavelengths incident at the same angle has the same exit angle; the angle amplification layer 142 is used to transmit large-angle incident light to a small-angle exit angle to meet the field of view of the camera 10, so as to the beam splitter 12.

[0057] Preferably, the superlens 14 is fabricated using CMOS technology. The superlens 14 can be either transmissive or reflective, and is a passive device. The magnification of the angle change is a constant value, and a tuning structure can be added to make the magnification adjustable.

[0058] The principles behind the angle magnification and dispersion compensation functions are as follows:

[0059] A single wavelength of light emitted from a point on the object under test is incident on a superlens at an angle θ1 degrees. The light output from the superlens is incident on a beam splitter at an angle θ1 / N, where N is the magnification. Figure 3 As shown. White light emitted from a point on the object under test is incident on the superlens at an angle θ2 degrees. The angle of the light emitted from the superlens is centered at θ2, forming an angle range [θ2 / N-δθ, θ2 / N+δθ], where δθ is the angle difference between the longest and shortest wavelength monochromatic light in the white light. After passing through a beam splitter, the light is incident on a liquid crystal spatial light modulator. While deflecting the incident light angle, the dispersion within the liquid crystal spatial light modulator is canceled out, ensuring that the emission angle of each wavelength of the emitted light remains consistent. The light is then converged to the same position on the camera target surface by the beam splitter and lens for imaging, as shown. Figure 4 As shown.

[0060] The design method for a superlens is as follows:

[0061] 1. Establish a database of mapping relationships between the phase and effective refractive index of nanostructure units.

[0062] The effective refractive index n corresponding to different nanostructure units was scanned using FDTD (Finite-Difference Time-Domain) optical simulation software. eff Establish the phase and effective refractive index n of the nanostructure unit. eff A database of mapping relationships between them.

[0063] like Figure 5 The diagram shows three different nanostructure units. These nanostructure units are randomly generated and are not limited to these three; they can be random arrangements and combinations of various structures.

[0064] The mapping relationship between the phase of the nanostructure unit and the effective refractive index is as follows:

[0065] (1)

[0066] in, Let n be the phase of the nanostructure unit at each position of the superlens, λ be the wavelength of the incident light, and n be the phase of the nanostructure unit at each position of the superlens. eff Let be the effective refractive index of each nanostructure unit, and h be the height of each nanostructure unit.

[0067] 2. Design of dispersion compensation structure

[0068] The formula for calculating the exit angle of incident light after passing through a superlens is as follows:

[0069] (2)

[0070] According to formula (2), at a certain exit angle θ, the phase distribution of light of different wavelengths before passing through the nanostructure unit of the superlens varies with the incident position coordinates as follows:

[0071] (3)

[0072] Where θ is the exit angle of the incident light after passing through the superlens. The phase distribution is introduced by the superlens, and x is the coordinate of the incident position of the incident light.

[0073] From formula (3), it can be seen that at a certain exit angle θ, for light of a single wavelength, the phase distribution introduced by the superlens is... It has a linear relationship with the incident position coordinate x of the incident light.

[0074] For example, the typical wavelengths of red, green, and blue light are 450nm, 532nm, and 633nm, respectively. Their phase distributions can be obtained from formula (3). A linear relationship graph between the incident position coordinate x and the incident light, as shown below. Figure 6 As shown. From Figure 6 As can be seen, the phase difference between light of different wavelengths changes with 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 light of different wavelengths a constant value.

[0075] like Figure 7 The figure shows the linear variation of the phase of light of different wavelengths after phase difference compensation with the incident position coordinate x. Taking green light as an example, Figure 6 The linear slope is assumed to be k. G ,but Figure 7 The slope of the linear curve is -k G The graph shows the phase of light of different wavelengths after phase difference compensation as a function of the incident position coordinate x. Figure 8 As shown, the phase difference between light of different wavelengths is a constant value at this time.

[0076] Therefore, as can be seen from formula (3), the phase of the arranged nanostructure units needs to satisfy formula (4). According to formula (4), nanostructure units are selected from the database and arranged at the corresponding positions of the superlens to offset the phase distribution introduced by the superlens and achieve the purpose of phase difference compensation.

[0077] (4)

[0078] in, Let be the phase distribution of light at each wavelength after phase difference compensation as a function of coordinate position x, and b be the phase difference adjustment constant.

[0079] 3. Design an angle-enlarged structure

[0080] like Figure 9 As shown, traditional methods use angle magnification devices based on lens groups for angle magnification. The lens group consists of convex and concave lenses. The lens group is large and easily damaged, which is not conducive to the integration and miniaturization of the imaging system.

[0081] Since angle magnification requires the focusing function of lenses, and both convex and concave lenses have focal points, this invention can replace traditional lens groups with superlenses. The focal lengths of the convex and concave lenses are f1 and f2, respectively, and the magnification is N = -f1 / f2; therefore, it is necessary to design a two-layer superlens structure that has the functions of a convex lens and a concave lens, and combine the two layer by layer to produce the angle magnification function.

[0082] The phase control principle of the superlens structure differs from that of traditional lens groups. The superlens controls the light wave through abrupt phase shifts in subwavelength micro / nano units, thereby controlling the beam direction. The wavefront phase distributions of the convex and concave lens layers in the angle magnification structure of the superlens are as follows:

[0083] (5)

[0084] (6)

[0085] Where f1 and f2 are the focal lengths of the convex lens layer and the concave lens layer, respectively. and Phase correction values ​​for the wavefront phase distribution of the convex and concave lens layers.

[0086] Adjust the focal lengths f1 and f2 according to formulas (5) and (6) so that the focal positions of the convex lens layer and the concave lens layer coincide, thus realizing the angle magnification function. Then, select nanostructure units from the database and arrange them at the corresponding positions of the superlens to complete the design of the angle magnification structure.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to 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, The application relates to a camera, a lens, a light-splitting prism, a liquid crystal spatial light modulator, a superlens and a computer. The camera is connected with the liquid crystal spatial light modulator and the computer through a cable, the camera is used for collecting image information and displaying on the computer, the lens is arranged in front of a lens of the camera, an optical axis of the camera is coaxial with an optical axis of the lens, the lens is used for converging light transmitted from the light-splitting prism to a target surface of the camera, the light-splitting prism is arranged between the liquid crystal spatial light modulator and the superlens, a horizontal optical axis of the light-splitting prism is coaxial with optical axes of the liquid crystal spatial light modulator and the superlens, and a vertical optical axis of the light-splitting prism is coaxial with the optical axis of the lens. The superlens is a three-layer nano-structure unit stacking structure, the uppermost layer is a dispersion compensation structure, and the lower two layers are angle amplification structures. The dispersion compensation structure is formed by arranging a plurality of nano-structure units on a silicon dioxide layer; the angle amplification structure comprises a convex lens layer and a concave lens layer, and the convex lens layer and the concave lens layer are both formed by arranging a plurality of nano-structure units on a silicon dioxide layer. The method for realizing the dispersion compensation function of the superlens is as follows: white light emitted by a certain point of a measured object is incident on the superlens at an angle of theta2, the angle of the light emitted by the superlens is centered on theta2, and an angle range of [theta2 / N-delta theta, theta2 / N+delta theta] is formed, wherein N is a magnification, and delta theta is an angle difference between monochromatic light of the longest wavelength and monochromatic light of the shortest wavelength in the white light; the light is irradiated on the liquid crystal spatial light modulator through the light-splitting prism, the dispersion in the liquid crystal spatial light modulator is offset while the angle of the incident light is deflected, the exit angle of the light of each wavelength remains consistent, and the light is converged on the same position on the target surface of the camera through the light-splitting prism and the lens to form an image. The white light emitted by the certain point of the measured object passes through the superlens, the angle amplification and the dispersion compensation functions are realized through the superlens, the light transmitted by the superlens passes through the light-splitting prism and reaches the liquid crystal spatial light modulator, the light reflected by the liquid crystal spatial light modulator passes through the light-splitting prism and reaches the lens, the camera collects image information and displays on the computer, the phase difference between the liquid crystal units of the liquid crystal spatial light modulator is changed by changing the voltage signal applied through the computer, so that the angle of the light beam emitted is changed.

2. The liquid crystal optical phased array imaging system of claim 1, wherein, The method for realizing the angle amplification function of the superlens is as follows: light of a single wavelength emitted by a certain point of a measured object is incident on the superlens at an angle of theta1, and the light output by the superlens is irradiated on the light-splitting prism at an angle of theta1 / N.

3. The liquid crystal optical phased array imaging system of claim 1, wherein, The design method of the superlens is as follows:

4. The liquid crystal optical phased array imaging system of claim 1, wherein, The mapping relationship between the nano-structure unit phase and the effective refractive index is as follows: Step 1, scanning the effective refractive index n corresponding to different nanostructure units by FDTD optical simulation software eff , establishing the mapping relationship database between the phase of nanostructure unit and the effective refractive index n eff . Step 2: according to formula (4), the nano-structure units are arranged at corresponding positions of the superlens from a database, so as to offset the phase distribution introduced by the superlens, and the purpose of phase difference compensation is achieved. （1） wherein, is the phase of the nanostructure unit at each position of the superlens, λ is the wavelength of the incident light, n eff is the effective refractive index of each nanostructure unit, h is the height of each nanostructure unit; The wavefront phase distribution of the convex lens layer and the concave lens layer in the angle amplification structure of the superlens is respectively as follows: （4） wherein, b is a phase difference adjustment constant, and θ is an exit angle of the incident light after passing through the superlens. According to formula (5) and (6), the focal lengths f1 and f2 are adjusted, the focal point positions of the convex lens layer and the concave lens layer are overlapped, then the nano-structure units are arranged at corresponding positions of the superlens from a database, and the design of the angle amplification structure is completed. （5） （6） wherein f1 and f2 are focal lengths of the convex lens layer and the concave lens layer, respectively, and a phase correction value of a wavefront phase distribution of the convex lens layer and the concave lens layer. ​ 5. The liquid crystal optical phased array imaging system of claim 1, wherein, 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.

6. The liquid crystal optical phased array imaging system of claim 1, wherein, The light splitting prism is a depolarization light splitting prism.

7. The liquid crystal optical phased array imaging system of claim 1, wherein, The liquid crystal spatial light modulator is a reflective phase modulation type device.

8. The liquid crystal optical phased array imaging system of claim 1, wherein, The super lens is processed by using a CMOS process, and the super lens is a transmission type or a reflection type.

Images