A common aperture imaging system for optical imaging and radar detection

Abstract

The present invention relates to the field of space detection technology, and specifically provides a common aperture imaging system for optical imaging and radar detection, comprising a coaxial reflector group with a common aperture for light waves and microwaves, a radar feed, an optical imaging system, and a frequency-dividing and light-splitting element for separating the light waves and microwaves, wherein the coaxial reflector group is not only used to collect light waves, but also forms a microwave transceiver antenna with the radar feed, responsible for transmitting and receiving microwaves, and the light waves collected by the coaxial reflector group are reflected by the frequency-dividing and light-splitting element toward the optical imaging system for optical imaging, while the microwaves are transmitted through the frequency-dividing and light-splitting element and directed toward the radar feed for radar detection. The present invention not only realizes a common aperture design for optical imaging and radar detection, but also arranges the radar feed and the optical imaging system on the same side of the coaxial reflector group, thereby reducing system complexity. In addition, the use of a frequency-dividing and light-splitting method for transmitting microwave-reflected light waves solves the problem of reduced optical imaging quality caused by multi-order diffraction of the metal grid.

Description

Technical Field

[0001] The present invention belongs to the technical field of space detection, and in particular relates to a common aperture imaging system for optical imaging and radar detection. Background Art

[0002] Synthetic aperture radar (SAR) and optical remote sensing cameras each possess unique observational advantages, and their combination can significantly enhance observation capabilities. SAR is an active imaging device that operates in the microwave band. It is not restricted by lighting conditions and has the ability to observe at all times of the day. Microwaves have a longer wavelength and are highly capable of penetrating clouds and fog, allowing them to operate stably in rain, snow, fog, and other weather conditions. SAR can also obtain target altitude information and has certain ranging and speed measurement capabilities. However, SAR can only display the electromagnetic scattering characteristics of a target in a specific wavelength band. The resulting black-and-white images do not reflect true color, requiring professional interpretation, resulting in poor readability and impaired observation capabilities in complex electromagnetic environments.

[0003] In contrast, while optical remote sensing cameras have limited imaging capabilities in adverse weather and at night, they offer clear, colorful images that can restore the true color of the target, better meeting the visual needs of the human eye. Furthermore, the high resolution of optical cameras helps reveal detailed features of the target area, facilitating target identification and description. By integrating the all-weather capabilities of SAR with the color information of optical remote sensing, the overall performance of observation equipment is enhanced.

[0004] Some solutions have been proposed for the co-aperture design of optical remote sensing and radar, such as the Chinese invention patent with publication number CN104502909A, published on April 8, 2015, and entitled "An Optical and Millimeter-Wave Radar Co-aperture Composite Detection System." This patent proposes to implement the co-aperture composite detection function of optical and millimeter-wave radar based on a large-aperture photoelectric theodolite. However, this method is mainly used for range measurement, space target detection, and multi-modal co-aperture composite guidance, and cannot be applied to ground detection. In addition, the optical receiving system and millimeter-wave radar transceiver system of the proposed solution are located on both sides of the primary mirror, which increases the complexity of the system structure.

[0005] The publication number is CN112485793A, the publication date is March 12, 2021, and the invention name is "Optical and radar co-aperture composite imaging system and method". The Chinese invention patent proposes an optical and radar co-aperture composite imaging system for remote sensing satellites. The spectrometer and frequency division unit is a transparent wave reflection microwave spectrometer and frequency division device, and a micron-level metal grid is used to reflect microwaves. However, the metal grid has the effect of a two-dimensional diffraction grating in the infrared band, which will produce multi-order diffraction, which has a certain impact on the imaging quality of the optical system. Although certain technical means can be effectively suppressed, it cannot be eliminated. Summary of the Invention

[0006] In view of this, the present invention aims to provide a common aperture imaging system for optical imaging and radar detection, which adopts a Cassegrain structure to receive light waves and simultaneously serves as a radar transceiver antenna. The frequency selective surface technology and wide spectrum high reflective film technology are used to design the frequency division and optical splitting elements, and the optical splitting and frequency division method of transmitting microwaves and reflecting light waves is adopted to solve the problem of reduced optical imaging quality caused by multi-level diffraction of the metal grid in the traditional method of transmitting light waves and reflecting microwaves.

[0007] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0008] The present invention provides a common aperture imaging system for optical imaging and radar detection, comprising:

[0009] Coaxial reflector groups with common apertures for light waves and microwaves, frequency division and beam splitting elements, radar feed sources, and optical imaging systems;

[0010] The coaxial reflector group is used to collect light waves and microwaves and direct them to the frequency division and beam splitting elements;

[0011] The frequency-dividing and beam-splitting elements are used to separate light waves from microwaves during the echo imaging process. Microwaves are transmitted by the frequency-dividing and beam-splitting elements and directed toward the radar feed source; light waves are reflected by the frequency-dividing and beam-splitting elements and directed toward the optical imaging system.

[0012] Radar feed is used for microwave transmission, reception and imaging;

[0013] The optical imaging system is used for receiving light waves and forming images.

[0014] Preferably, the coaxial reflector group is a Cassegrain structure, including a primary mirror and a secondary mirror.

[0015] Preferably, the primary mirror, the secondary mirror and the radar feed constitute a transceiver antenna. When the radar feed transmits microwaves, the microwaves are transmitted by the frequency-division and light-division elements and directed toward the secondary mirror. The secondary mirror reflects the microwaves toward the primary mirror, which then emits the microwaves.

[0016] Preferably, the frequency-dividing and optical-splitting device uses a frequency-selective surface and a spectral reflective film to separate light waves and microwaves.

[0017] Preferably, the frequency-dividing and light-splitting element includes a dielectric reflective film for reflecting light waves and a frequency selective surface for transmitting microwaves.

[0018] Preferably, the dielectric reflective film is used to reflect light waves in the visible and infrared bands, and the material of the dielectric reflective film is metal fluoride or semiconductor material.

[0019] Preferably, the radar feed and the optical imaging system are arranged on the same side of the primary mirror.

[0020] Preferably, the optical imaging system includes an infrared imaging system and a visible light imaging system, and the light waves are split into infrared bands and visible light by a spectroscope, and the infrared bands are directed to the infrared imaging system, and the visible light is directed to the visible light imaging system.

[0021] Preferably, the frequency-division and light-splitting element further includes: a graphene control layer, and the microwave transmittance of the frequency-division and light-splitting element is changed by controlling the voltage applied to the graphene control layer.

[0022] Preferably, the graphene control layer includes a graphene layer, a gate dielectric layer and a top gate electrode, wherein the top gate electrode is used to provide a controllable voltage, and the voltage of the top gate electrode is applied to the graphene layer through the gate dielectric layer. When voltage is applied to the graphene layer, the surface conductivity of the graphene layer increases, and it is in an absorption state for microwaves, and the power of microwaves transmitted through the frequency division and light splitting element is reduced; when no voltage is applied to the graphene layer, the microwaves are completely transmitted through the frequency division and light splitting element.

[0023] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0024] The present invention adopts frequency selective surfaces (FSS) technology and wide-spectrum high-reflection film technology to achieve efficient separation of light waves and microwaves. Utilizing frequency selective surface technology, a miniaturized, multipole unit structure is adopted as the initial structure of the frequency selective surface, and auxiliary dielectric matching technology is used to optimize the macroscopic order to achieve efficient frequency division of light waves and microwaves. At the same time, through the continuous combination and iteration of reflective film systems in different bands, the reflection bandwidth is broadened, and the Ka-band transmittance of the frequency division and spectrometer elements is achieved to be higher than 90%, and the 450-900nm and medium-wave infrared reflectivity is higher than 95%. The above-mentioned microwave-transmitting and light-reflecting light wave splitting and frequency division method avoids the problem of optical imaging quality degradation caused by multi-order diffraction of the metal grid in the traditional light-transmitting and microwave-reflecting method, and effectively improves the clarity and resolution of optical imaging.

[0025] The optical imaging system and radar of the present invention share the primary mirror and the secondary mirror, and the optical imaging system and the radar are arranged on the same side of the primary mirror, which reduces the complexity and overall size of the system and can simultaneously achieve synchronous phase imaging of visible light, infrared light and radar.

[0026] In addition, the present invention innovatively designs a graphene control layer in the frequency division and spectrometer element. By controlling the applied voltage, the microwave channel of the frequency division and spectrometer element can be controlled to be closed and opened. The microwave channel is only opened when imaging is required, allowing microwaves to pass through the frequency division and spectrometer element. The microwaves are shielded at other times and are not allowed to pass through the frequency division and spectrometer element, thereby enhancing the stealth performance of the radar platform and preventing high-power microwaves from interfering with the onboard computing, communication, and power supply systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0028] Figure 1 2 is a schematic structural diagram of a common aperture imaging system for optical imaging and radar detection provided by an embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of the physical model structure of the frequency division and light splitting element provided according to an embodiment of the present invention;

[0030] Figure 3 2. A schematic diagram of a FSS structure model after dielectric matching according to an embodiment of the present invention;

[0031] Figure 4 is a schematic diagram of forming a multipole resonant FSS pattern according to an embodiment of the present invention;

[0032] Figure 5 1 is a schematic diagram of the physical model structure of a frequency-division and light-division component with microwave shielding function provided in accordance with an embodiment of the present invention;

[0033] Figure 6 is a schematic structural diagram of a graphene control layer provided according to an embodiment of the present invention;

[0034] Figure 7 is a structural block diagram of a radar transceiver system provided according to an embodiment of the present invention;

[0035] Figure 8 Schematic diagram of an off-focus feed array provided according to an embodiment of the present invention.

[0036] Reference numerals include:

[0037] Primary mirror 1, secondary mirror 2, frequency-dividing and beam-splitting element 3, radar feed 4, reflector 5, beam splitter 6, visible light imaging system 7, infrared imaging system 8;

[0038] Protective film 31 , dielectric reflective film 32 , frequency selective surface 33 , substrate 34 , dielectric anti-reflection film 35 , graphene control layer 36 , graphene layer 361 , gate dielectric layer 362 , top gate electrode 363 . DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention. Similar elements in different embodiments use associated similar element numbers. In the following embodiments, many detailed descriptions are intended to enable the present invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present invention are not shown or described in the specification. This is to avoid the core part of the present invention being overwhelmed by too much description. For those skilled in the art, it is not necessary to describe these related operations in detail. They can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0040] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various orders in the description and the drawings are only for the purpose of clearly describing a certain embodiment and are not intended to be a required order, unless otherwise specified that a certain order must be followed.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0042] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0043] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0044] See also Figure 1 In one embodiment of the present invention, a common aperture imaging system for optical imaging and radar detection is provided, which adopts a common aperture design for optical imaging and radar detection to achieve simultaneous imaging of visible light, infrared light and radar of the detection target. Specifically, the system includes: a coaxial reflector group, a frequency-dividing and beam-splitting element 3, an optical imaging system and a radar transceiver imaging system, wherein the imaging system of the embodiment of the present invention can achieve common aperture imaging of optics and radar, and the coaxial reflector group is a common aperture structure for light waves and microwaves. In an embodiment of the present invention, the coaxial reflector group adopts a Cassegrain structure, including a primary mirror 1 with a concave spherical reflective surface and a secondary mirror 2 with a convex spherical reflective surface. Both the primary mirror 1 and the secondary mirror 2 are made of silicon carbide material, and the primary mirror 1 adopts a back-opening triangular rib lightweight structure design, which significantly reduces the weight while ensuring structural strength. In addition, the main mirror 1 is connected to the structural parts by inlaid Invar bushings and titanium alloy flexible joints. This connection method not only enhances the supporting stability of the main mirror 1, but also has certain shock absorption and deformation adaptability, ensuring that the main mirror 1 can maintain a high-precision working state in a complex space-based environment.

[0045] As an optional embodiment, a shape memory alloy wire is embedded in the support structure of the secondary mirror 2. When the curvature of the secondary mirror 2 needs to be adjusted to optimize the focusing performance of light waves and microwaves, power is applied to cause the shape memory alloy wire to contract, causing the support structure of the secondary mirror to deform, thereby changing the curvature of the secondary mirror.

[0046] When receiving the light waves and microwaves reflected by the detection target, the collimated input light waves and microwaves are first directed to the primary mirror 1, which changes the propagation direction of the light waves and microwaves so that they are directed to the secondary mirror 2. After the secondary mirror 2 reflects the light waves and microwaves, the light waves and microwaves are directed to the frequency division and beam splitting element 3 in a parallel state.

[0047] Frequency-dividing and beam-splitting element 3 is used to separate light waves from microwaves during the echo imaging process. It reflects light waves and transmits microwaves. Frequency-dividing and beam-splitting element 3 is tilted at a 45-degree angle to facilitate separation of light waves and microwaves. After being transmitted by frequency-dividing and beam-splitting element 3, microwaves are directed toward radar feed 4 for subsequent radar detection and imaging. Light waves are reflected by frequency-dividing and beam-splitting element 3 and directed toward the optical imaging system, achieving optical imaging. In this embodiment of the present invention, frequency-dividing and beam-splitting element 3 is required to achieve a light-to-wave and frequency-dividing method by transmitting microwaves and reflecting light waves. Therefore, a frequency-selective surface (FSS) and a spectral reflective film are used to separate light waves from microwaves. The frequency-selective surface (FSS) is designed using frequency-selective surface technology combined with a multipole unit structure. The FSS structure is precisely analyzed and optimized using auxiliary dielectric matching technology to achieve efficient frequency separation. Furthermore, through the continuous combination and iteration of reflective film systems with different wavelength bands, the reflection bandwidth is broadened, and a reflective film with reflective properties for visible light and mid-wave infrared is designed to achieve efficient spectrometry.

[0048] Specifically, such as Figure 2 As shown, the frequency-dividing and light-splitting element 3 includes a protective film 31, a dielectric reflective film 32, a frequency selective surface 33, a substrate 34 and a dielectric anti-reflection film 35 in sequence, wherein the side surface provided with the protective film 31 is close to the primary mirror 1, and the side surface provided with the dielectric anti-reflection film 35 is away from the primary mirror 1. The protective film 31 is used to protect the dielectric reflective film 32, and it has no special optical effect on light waves and microwaves. The dielectric reflective film 32 is a multi-layer film structure. Since the optical imaging requirements are visible light imaging and infrared imaging, a film material suitable for high reflectivity of visible light and medium-wave infrared can be selected from metal fluorides or semiconductor materials. A variety of material layers with different refractive indices are stacked and designed, and the multi-band reflective film system is continuously optimized and iterated to broaden the reflection bandwidth and ensure high transmittance to microwaves. In this embodiment of the present invention, YbF3, which has a low refractive index for visible light and infrared light, ZnSe, which has a medium refractive index, and Ge, which has a high refractive index, are specifically used. The average refractive index of the YbF3 material is 1.37, the average refractive index of the ZnSe material is 2.46, and the average refractive index of the Ge material is 4. Testing has shown that the dielectric reflective film 32 has a reflectivity exceeding 95% for the 450-900nm band and mid-wave infrared, and a transmittance exceeding 90% for microwaves in the Ka band (microwaves with a frequency range of 26.5 to 40 GHz), effectively separating light waves from microwaves.

[0049] For the model parameter design of the frequency division and light splitting element 3, the embodiment of the present invention uses auxiliary dielectric matching technology to accurately analyze the frequency selective surface 33. Considering the "symmetry" principle of dielectric matching, the following is constructed: Figure 3 The frequency selective surface 33 after dielectric matching is shown, wherein z=0 represents the multipole electric resonance FSS pattern of the frequency selective surface 33, and and Represent the dielectric plates on both sides of the multipole electric resonant FSS pattern, where represents the thickness of the first dielectric plate, represents the dielectric constant of the first dielectric plate, represents the magnetic permeability of the first dielectric plate, The thickness of the second dielectric plate, represents the dielectric constant of the second dielectric plate, The magnetic permeability of the second dielectric plate is expressed as The relative magnetic permeability of the incident space and the exit space are expressed as express.

[0050] The electric and magnetic fields of the first and second dielectric plates are expanded into a series of infinite Floquet modes. The continuity boundary condition of the electromagnetic field at the dielectric interface can be used to establish electromagnetic field equations on both sides of the interface. By solving the equations, the transmitted electromagnetic field can be obtained, and then the frequency selective surface 33 can be obtained.

[0051] Microwave and Reflection occurs at both interfaces, so The free space and There will be incident waves and reflected waves in the first dielectric plate. The electric field of the incident wave and magnetic field They are:

[0052] ;

[0053] ;

[0054] Electric field of reflected wave and magnetic field They are:

[0055] ;

[0056] .

[0057] in, represents the incident wave, represents the reflected wave, Represents the pattern of electromagnetic waves, such as Indicates TE (Transverse Electric mode) mode, Indicates TM (Transverse Magnetic mode) mode, Indicates the range of the medium area, express Medium area, express Medium area, express Medium area, Indicates the range of the medium area The amplitude of the internal incident wave, Indicates the range of the medium area The amplitude of the internal reflection wave, Indicates along z The unit vector in the positive direction of the axis, The unit vector representing the polarization direction of the electric field, Indicates in the medium area The wave impedance of the internal electromagnetic wave, the subscript 00 represents the (0,0) order Floquet mode, Indicates in the medium area The propagation constant of the internal electromagnetic wave, represents the natural logarithm, Is an imaginary unit.

[0058] exist According to the electromagnetic field continuity boundary condition, we can get:

[0059] ;

[0060] .

[0061] Combining the above operations, we can get:

[0062] ;

[0063] .

[0064] Since the electric field of any order Floquet mode is continuous, The interface satisfies:

[0065] ;

[0066] in, Indicates that it is located medium area The Floquet electric field mode, Indicates that it is located medium area Floquet electric field pattern.

[0067] However, due to the existence of multipole electric resonance FSS pattern, At any level The magnetic field of the Floquet mode is discontinuous, so Media area and The Floquet magnetic field patterns in the dielectric region all satisfy:

[0068] ;

[0069] ;

[0070] in, Indicates the thickness of the dielectric area. hour, ;when hour, ,for ,when When The equivalent mode resistance of the Floquet mode in the input direction is When The equivalent mode resistance of the Floquet mode in the output direction is Indicates the (m,n)-order Floquet mode in the dielectric region The propagation constant within .

[0071] For the medium area The electromagnetic field inside is divided into two parts, one part comes from the interface The transmission field on the left and the interface on the other Therefore, For the interface, negative direction The electromagnetic field on is:

[0072] ;

[0073] ;

[0074] Among them, the parameters and is defined as follows:

[0075] ;

[0076] .

[0077] by For the interface, positive direction The electromagnetic field on is:

[0078] ;

[0079] .

[0080] We can further obtain:

[0081] ;

[0082] in, 、 and is the unknown coefficient, aperture It represents the non-pattern area on the multipole electric resonance FSS pattern where there is no metal and electromagnetic waves can pass through. Metal represents the metal area on the multipole electric resonance FSS pattern used to reflect electromagnetic waves and constitutes the boundary of FSS.

[0083] By using the basis function to expand the electric field at the aperture Ω, the expansion coefficient can be solved using the moment method, thereby further obtaining the unknown coefficient 、 and , we can get the electromagnetic field distribution in the dielectric region II, and solve the unknown coefficients as follows:

[0084] ;

[0085] ;

[0086] .

[0087] Assume that The electric and magnetic fields in free space are and ;use The electromagnetic field continuity boundary condition at can be obtained:

[0088] ;

[0089] .

[0090] The range of the dielectric region can be further obtained Amplitude of internal electromagnetic waves for:

[0091] .

[0092] This allows for free space to be designed The transmitted electromagnetic field, such as Figure 4 As shown, the multipole resonant FSS pattern forms a complex electromagnetic response through the combination of different resonant modes, thereby realizing electromagnetic wave control in a wide frequency band.

[0093] Based on the multipole resonance principle and the calculation of electromagnetic parameters through the auxiliary dielectric matching technology, a frequency selective surface 33 can be designed. The frequency division and light splitting element 3 prepared using the frequency selective surface 33 has an average passband transmittance increased to 99% after testing.

[0094] As an optional embodiment, a liquid crystal film is added between the frequency selective surface 33 and the dielectric reflective film 32, and transparent electrodes are placed on both sides of the liquid crystal film. By controlling the voltage between the electrodes, the alignment of the liquid crystal molecules is adjusted, thereby changing the transmittance of light and microwaves. To increase light reflectivity, a specific voltage is applied to align the liquid crystal molecules, enhancing light reflection. To increase microwave transmittance, a specific voltage is applied to disrupt the alignment of the liquid crystal molecules, reducing microwave scattering and reflection.

[0095] As an alternative embodiment, see Figure 5 The frequency-dividing and beam-splitting element 3 sequentially comprises a protective film 31, a dielectric reflective film 32, a plurality of film units alternately arranged by frequency-selective surfaces 33 and substrates 34, a graphene control layer 36, and a dielectric anti-reflection film 35. The graphene control layer 36 acts as a switch to control whether the frequency-dividing and beam-splitting element 3 allows microwaves to pass through. Figure 6The graphene control layer 36 includes a graphene layer 361, a gate dielectric layer 362 and a top gate electrode 363 in sequence, wherein the graphene layer 361 is a carrier conductive layer that controls microwave propagation by changing the surface conductivity in response to an applied voltage; the gate dielectric layer 362 serves as an insulating layer but allows electric field regulation, that is, when a certain control voltage is applied to the top gate electrode 363, the electric field will be transmitted to the graphene layer 361 through the gate dielectric layer 362, causing the surface conductivity of the graphene layer 361 to change; the top gate electrode 363 is used to provide a control voltage, and the preparation material of the top gate electrode 363 can be selected from indium tin oxide that is transparent to microwaves. When a voltage is applied to the top gate electrode 363, the control voltage is transmitted through the gate dielectric layer 362 to the graphene layer 361. At this point, the surface conductivity of the graphene layer 361 increases, and the graphene layer 361 absorbs microwaves. Microwaves incident on the frequency-dividing and beam-splitting element 3 are absorbed by the graphene layer 361, preventing them from passing through the frequency-dividing and beam-splitting element 3, and the microwave channel is closed. At this point, the radar feed 4 cannot transmit microwaves or receive microwave echoes, rendering the imaging system platform invisible. When microwaves need to be transmitted or received, no voltage is applied to the top gate electrode 363. At this point, the graphene layer 361 becomes transparent to microwaves, meaning microwaves can pass through it, and the microwave channel of the frequency-dividing and beam-splitting element 3 is open. Furthermore, the microwave absorptivity of the graphene layer 361 can be adjusted by controlling the voltage applied to the top gate electrode 363, so that some microwaves are absorbed while others pass through the frequency-dividing and beam-splitting element 3, thereby controlling the microwave power that passes through the frequency-dividing and beam-splitting element 3. In this embodiment of the present invention, the graphene control layer 36 can control the selective transmission of microwaves by the frequency-dividing and beam-splitting element 3, offering advantages such as fast control speed and low latency. The design of the graphene control layer 36 enables the frequency-dividing and beam-splitting element 3 to open the microwave channel only when microwave imaging is required, while shielding microwaves at other times. This enhances the stealth performance of the imaging system platform and prevents high-power microwaves from interfering with onboard computing, communication, and power systems.

[0096] The microwave is transmitted by the frequency division and light division element 3 and directed to the radar receiving imaging system, such as Figure 7As shown, the radar receiving and imaging system includes a transceiver antenna, a power amplifier unit, a central electronics unit, a data recording unit, a master control unit, and a power supply unit. The power supply unit provides power to all components in the radar transceiver imaging system. The master control unit controls the radar operating mode and coordinates the operation of each module. The central electronics unit is responsible for microwave parameter design and coordinates microwave transmission and reception. The data recording unit stores microwave data collected by the radar, including transmitted and received signals, target information, and other relevant system data. The power amplifier unit amplifies the power of the radar's transmitted signal, ensuring that the microwaves are effectively radiated into space and cover the required detection range. The transceiver antenna includes a primary mirror 1, a secondary mirror 2, and a radar feed 4. During microwave transmission, the radar feed 4 converts the high-frequency electrical signal from the power amplifier unit into a directionally propagating microwave signal. The microwaves then pass through the frequency-dividing and light-dividing element 3 and are directed toward the secondary mirror 2. The secondary mirror 2 reflects the microwaves toward the primary mirror 1, which then transmits the microwaves outward. When the radar feed source 4 receives microwave echoes, the collimated incident microwaves are reflected by the primary mirror 1 toward the secondary mirror 2, and then reflected by the secondary mirror 2 toward the frequency-dividing and beam-splitting element 3. After passing through the frequency-dividing and beam-splitting element 3, they are directed toward the radar feed source 4. Figure 8 As shown, the radar feed 4 is Arranged off-focus feed array.

[0097] The light wave is reflected by the frequency-dividing and spectroscopic element 3 and directed toward the optical imaging system. According to the imaging detection requirements, the optical imaging system includes a visible light imaging system 7 and an infrared imaging system 8. In order to realize the transmission of light waves and the separation of light waves and visible light, a reflector 5 and a spectroscope 6 are also provided in the optical path. Specifically, after the light wave is reflected by the frequency-dividing and spectroscopic element 3, it is first directed toward the reflector 5. The reflector 5 reflects the light wave toward the spectroscope 6. The spectroscope 6 is used to realize the separation of visible light and infrared bands. The spectroscope 6 can be designed to reflect visible light and transmit infrared bands, or it can be designed to transmit visible light and reflect infrared bands. In an embodiment of the present invention, the visible light in the light wave is reflected by the spectroscope 6 toward the visible light imaging system 7 to realize visible light imaging. The infrared band in the light wave is transmitted by the spectroscope 6 and directed toward the infrared imaging system 8 to realize infrared imaging. Since the imaging system of the embodiment of the present invention is mainly used for space-based large-field-of-view imaging, it has high requirements for the imaging target surface. The sensors of the visible light imaging system 7 and the infrared imaging system 8 are specifically composed of multiple splicable imaging detection chips, and visible light and infrared imaging of large-field-of-view targets are achieved through synchronous control.

[0098] The optical imaging and radar detection common aperture imaging system of the present invention not only realizes the arrangement of the radar feed source 4, the visible light imaging system 7 and the infrared imaging system 8 on the same side relative to the primary mirror 1, thereby reducing the space of the entire machine, but also realizes the separation of light waves and microwaves through frequency selective surface technology and wide-spectrum high-reflection film technology, realizes the design of transmitting microwaves and reflecting light waves, and solves the problem of reduced optical imaging quality caused by multi-order diffraction of the metal grid in the traditional transmission light wave and reflection microwave design scheme.

[0099] In short, the above description is only a preferred embodiment of this specification and is not intended to limit the scope of protection of this specification. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this specification shall be included in the scope of protection of this specification.

[0100] The systems, devices, modules, or units described in one or more of the above embodiments may be implemented by a computer chip or entity, or by a product having a certain function. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0101] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0102] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0103] The foregoing description of this specification describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different from that described in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order shown or the sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. An optical imaging and radar detection common aperture imaging system, characterized in that: include: Coaxial reflector groups with common apertures for light waves and microwaves, frequency division and beam splitting elements, radar feed sources, and optical imaging systems; The coaxial reflector group is used to collect light waves and microwaves and direct the light waves and microwaves toward the frequency division and light splitting element; The frequency-dividing and light-splitting element is used to separate light waves from microwaves during the echo imaging process. The microwaves are transmitted by the frequency-dividing and light-splitting element and directed toward the radar feed source; the light waves are reflected by the frequency-dividing and light-splitting element and directed toward the optical imaging system. The frequency-dividing and light-splitting element comprises: a graphene control layer, wherein the microwave transmittance of the frequency-dividing and light-splitting element is changed by controlling the voltage applied to the graphene control layer; the graphene control layer comprises a graphene layer, a gate dielectric layer, and a top gate electrode, wherein the top gate electrode is used to provide a controllable voltage, and the voltage of the top gate electrode is applied to the graphene layer through the gate dielectric layer. When a voltage is applied to the graphene layer, the surface conductivity of the graphene layer increases, and the graphene layer is in an absorbing state for microwaves, and the power of microwaves transmitted through the frequency-dividing and light-splitting element is reduced; when no voltage is applied to the graphene layer, microwaves are completely transmitted through the frequency-dividing and light-splitting element; The radar feed is used for microwave transmission, reception and imaging; The optical imaging system is used for receiving light waves and forming images.

2. The optical imaging and radar detection common aperture imaging system according to claim 1, characterized in that: The coaxial reflector group is a Cassegrain structure, including a primary mirror and a secondary mirror.

3. The optical imaging and radar detection common aperture imaging system according to claim 2, characterized in that: The primary mirror, the secondary mirror and the radar feed source constitute a transceiver antenna. When the radar feed source transmits microwaves, the microwaves are transmitted by the frequency-division and light-division elements and directed toward the secondary mirror. The secondary mirror reflects the microwaves toward the primary mirror, which then emits the microwaves.

4. The optical imaging and radar detection common aperture imaging system according to claim 1, characterized in that: The frequency-dividing and light-dividing device uses a frequency-selective surface and a spectrum-reflecting film to separate light waves and microwaves.

5. The optical imaging and radar detection common aperture imaging system according to claim 1, characterized in that: The frequency division and light splitting element includes a dielectric reflection film for reflecting light waves and a frequency selective surface for transmitting microwaves.

6. The optical imaging and radar detection common aperture imaging system according to claim 5, characterized in that: The dielectric reflective film is used to reflect light waves in the visible and infrared bands, and the material of the dielectric reflective film is metal fluoride or semiconductor material.

7. The optical imaging and radar detection common aperture imaging system according to claim 2, characterized in that: The radar feed and the optical imaging system are arranged on the same side of the primary mirror.

8. The optical imaging and radar detection common aperture imaging system according to claim 1, characterized in that: The optical imaging system includes an infrared imaging system and a visible light imaging system. The light wave is split into an infrared band and visible light by a spectroscope, and the infrared band is directed to the infrared imaging system, and the visible light is directed to the visible light imaging system.

Images