WO2018196245A1 - 一种近景微波成像方法及系统 - Google Patents

一种近景微波成像方法及系统 Download PDF

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WO2018196245A1
WO2018196245A1 PCT/CN2017/100397 CN2017100397W WO2018196245A1 WO 2018196245 A1 WO2018196245 A1 WO 2018196245A1 CN 2017100397 W CN2017100397 W CN 2017100397W WO 2018196245 A1 WO2018196245 A1 WO 2018196245A1
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echo signal
dimensional image
preset
target object
image data
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PCT/CN2017/100397
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English (en)
French (fr)
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祁春超
吴光胜
赵术开
肖千
王爱先
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华讯方舟科技有限公司
深圳市无牙太赫兹科技有限公司
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Priority to US16/607,577 priority Critical patent/US11561300B2/en
Publication of WO2018196245A1 publication Critical patent/WO2018196245A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/904—SAR modes
    • G01S13/9064—Inverse SAR [ISAR]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/887—Radar or analogous systems specially adapted for specific applications for detection of concealed objects, e.g. contraband or weapons
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N22/00—Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/04—Systems determining presence of a target
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • G01S7/411—Identification of targets based on measurements of radar reflectivity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/12—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation operating with electromagnetic waves

Definitions

  • the embodiments of the present invention belong to the field of near-field microwave imaging technology, and in particular, to a near-field microwave imaging method and system.
  • the close-range microwave imaging technology uses an array antenna to rotate around a specific rotating shaft to form a curved surface, and scans an object by actively transmitting electromagnetic waves in a microwave band, because it can penetrate the surface of the object and detect metal or non-metallic contraband hidden inside the object. Because of its small radiation dose and non-ionizing radiation, it is widely used in security inspection systems to perform human safety inspection tasks.
  • the near-field microwave imaging technology has a large amount of data processing and high imaging accuracy because of the curved scanning path, and is not easy to implement, and is difficult to widely use.
  • the embodiment of the invention provides a near-field microwave imaging method and system, which aims to solve the problem that the near-field microwave imaging technology is difficult to widely promote due to the curved scanning path, large data processing amount, high imaging precision requirement, and is not easy to implement. .
  • An embodiment of the present invention provides a near-field microwave imaging method, including:
  • Another aspect of the embodiments of the present invention further provides a close-range microwave imaging system, including:
  • the first echo signal processing module is configured to perform Fourier transform on the echo signal reflected by the target object obtained by rotating the array antenna around the preset rotation axis to obtain a first echo signal, where the first echo signal is obtained.
  • An echo signal is expressed in polar form;
  • the second echo signal processing module multiplies the first echo signal and the preset reference function to obtain a second echo signal
  • a third echo signal processing module converts the second echo signal into a rectangular coordinate form by a preset algorithm to obtain a third echo signal
  • the three-dimensional image data processing module performs three-dimensional Fourier transform on the third echo signal to obtain three-dimensional image data of the target object.
  • the echo signals reflected by the target object obtained by rotating the array antenna around the preset rotation axis in the frequency domain are subjected to Fourier transform, reference function multiplication, and coordinate conversion processing, and finally the echo signals can be polar coordinates.
  • the form is converted into a rectangular coordinate form, so that the three-dimensional image data of the target object can be quickly obtained, and the target object can be quickly imaged, the data processing amount is small, the imaging precision is high, and it is easy to implement, and is suitable for widespread use.
  • FIG. 1 is a schematic diagram of a cylindrical scanning system in a Cartesian coordinate system provided by an embodiment of the present invention
  • FIG. 2 is a flow chart of a close-range microwave imaging method according to an embodiment of the present invention.
  • FIG. 3 is a block diagram showing the flow of step S30 in FIG. 2 according to an embodiment of the present invention.
  • FIG. 4 is a flow chart of a close-range microwave imaging method according to another embodiment of the present invention.
  • FIG. 5 is a structural block diagram of a close-range microwave imaging system according to an embodiment of the present invention.
  • FIG. 6 is a structural block diagram of a third echo signal processing module of FIG. 5 according to an embodiment of the present invention.
  • FIG. 7 is a structural block diagram of a close-range microwave imaging system according to another embodiment of the present invention.
  • All embodiments of the present invention are implemented based on a near-field microwave imaging system consisting of an array antenna, a signal transceiving device, and a mechanical rotating device and signal processing device consisting of a linear array of predetermined number of antennas.
  • the signal processing device may employ a graphics processing unit (GPU).
  • GPU graphics processing unit
  • the mechanical rotating device controls the rotation of the array antenna, and the signal transceiving device transmits a signal through the array antenna during the rotation process and receives an echo signal reflected by the target object to be imaged, and the signal transceiving device sends the echo signal to the signal processing device for processing as an imaging result. Scanning imaging of each sample point on the target object is achieved.
  • the near-field microwave imaging system can be classified into a curved surface scanning system or a cylindrical scanning system according to the shape of the scanning surface formed by the equivalent phase position during the rotation of the array antenna.
  • the plurality of antennas form an array antenna in a Z-axis direction perpendicular to the horizontal plane, and the distance of the array antenna from the geometric central axis of the cylindrical scanning system (ie, the preset rotation axis) is R (ie, the rotation radius of the antenna array is R), the array After the antenna rotates around the geometric central axis (ie, 360°), it is equivalent to form a plurality of equivalent antenna positions of equal azimuth intervals and equal height intervals distributed on the cylinder surface, and the equivalent antenna position is called an antenna equivalent.
  • the phase center realizes three-dimensional imaging of the target object by acquiring echo signals reflected by the target object collected at the equivalent phase center positions of all equivalent antennas.
  • an embodiment of the present invention provides a short-range microwave imaging method, including:
  • Step S10 performing Fourier transform on the echo signal reflected by the target object obtained by rotating the array antenna around the preset rotation axis to obtain a first echo signal, and the first echo signal is in polar coordinates.
  • the array antenna of the cylindrical scanning system can be placed perpendicular to the horizontal plane, placed parallel to the horizontal plane or tilted, and can be selected according to actual needs; the Fourier transform can be selected by parallel fast Fourier transform, that is, At the same time, the echo signals collected at the equivalent phase center position of each equivalent antenna are processed to speed up the data processing.
  • the embodiment is implemented based on the cylindrical scanning system shown in FIG. 1, that is, the array antenna is placed perpendicular to the horizontal plane, the preset rotating shaft coincides with the Z axis in FIG. 1, and the preset rotating axis is the Z-axis direction.
  • the echo signal in step S10 includes reflected signals reflected by a plurality of sampling points on the target object acquired at the equivalent phase center positions of all equivalent antennas.
  • the polar representation of the echo signal is defined as:
  • ⁇ is the rotation angle of the array antenna rotating around the preset rotation axis
  • f is the frequency of the transmission signal of the array antenna
  • C is the speed of light
  • z is the echo signal
  • the acquisition height in the preset rotation axis ie, the echo signal is acquired at the equivalent phase center position of the equivalent antenna with the coordinate z).
  • the polar representation of the first echo signal is:
  • k z is the number of two-way waves corresponding to the equivalent antenna with the coordinate z on the preset rotation axis.
  • the values of the variables in the equations (1) and (2) are different, that is, signals corresponding to different equivalent antennas.
  • Step S20 Multiply the first echo signal and the preset reference function to obtain a second echo signal.
  • the first reference signal is multiplied by the preset reference function for phase compensation of the first echo signal.
  • the expression of the second echo signal is:
  • H(f) is an expression of the preset reference function
  • R is the radius of rotation of the array antenna around the preset axis of rotation (see R in Figure 1); the values of the variables in equation (3) represent different signals corresponding to different equivalent antennas.
  • Step S30 Converting the second echo signal into a rectangular coordinate form by a preset algorithm to obtain a third echo signal.
  • the second echo signal is represented in polar form, and the second echo signal is converted into a rectangular coordinate form, that is, the reflected signal collected at the equivalent phase center position of each equivalent antenna is corresponding to Each coordinate position on the imaging area in the Cartesian coordinate system shown in FIG.
  • the rectangular coordinate representation of the third echo signal is:
  • k x is the number of two-way waves corresponding to the equivalent antenna with the coordinate x in the X-axis direction
  • k y is the number of two-way waves corresponding to the antenna with the coordinate y in the Y-axis direction
  • Different means the signal corresponding to different equivalent antennas.
  • the preset algorithm may be an interpolation algorithm, for example, a nearest neighbor interpolation algorithm, a linear interpolation algorithm, a polar coordinate interpolation algorithm, or a spline interpolation method.
  • Step S40 performing a three-dimensional Fourier transform on the third echo signal to obtain three-dimensional image data of the target object.
  • the expression of the three-dimensional image data of the target object is:
  • x is the coordinate of the equivalent antenna in the X-axis direction
  • y is the coordinate of the equivalent antenna in the Y-axis direction
  • z is the coordinate of the equivalent antenna in the Z-axis direction.
  • step S40 the method further includes:
  • the three-dimensional image information in the three-dimensional image data is extracted to obtain a three-dimensional image of the target object.
  • the three-dimensional Cartesian coordinate system is the Cartesian coordinate system shown in FIG.
  • the echo signals of each sampling point on the target object correspond to the rectangular coordinate form.
  • a set of rectangular coordinate values in the represented three-dimensional image data so that the rectangular coordinate values corresponding to the sampling points in a certain two-dimensional region on the target object can be extracted from the three-dimensional image data according to actual needs, and the two-dimensional region can be obtained.
  • the two-dimensional image information in the same way, only needs to extract the rectangular coordinate values corresponding to the sampling points in a certain three-dimensional region on the target object, and the three-dimensional image information of the three-dimensional region can be obtained.
  • the echo signals reflected by the target object obtained by rotating the array antenna around the preset rotation axis in the frequency domain are subjected to Fourier transform, reference function multiplication, and coordinate conversion processing, and finally the echo signals can be formed by polar coordinates. It is converted into a rectangular coordinate form, so that the three-dimensional image data of the target object can be quickly obtained, and the target object can be quickly imaged, the data processing amount is small, the imaging precision is high, and it is easy to implement, and is suitable for widespread use.
  • step S30 in the embodiment corresponding to FIG. 2 specifically includes:
  • Step S31 Establish a grid having a preset size and a preset sampling interval, the grid being represented in Cartesian coordinates.
  • the expression of the grid is:
  • the values of the variables in the formula (6) are different, that is, the grids with different coordinates in the Cartesian coordinate system; the preset size refers to the area size of each grid, which can be set according to actual needs.
  • each grid as long as the maximum length and width greater than [-4 ⁇ f max / C, 4 ⁇ f max / C] to the range, i.e. in the (k x, k y) k x and k y are required to satisfy the following relationship formula:
  • f max is the maximum value of the frequency of the transmitted signal.
  • the preset sampling interval refers to the distance between two adjacent grids, that is, the linear distance between geometric center points of two adjacent grids, and two adjacent rows arranged along the X-axis direction.
  • the distance between the grids is set to ⁇ k x
  • the distance between two adjacent grids arranged along the X-axis direction is set to ⁇ k y
  • ⁇ k x and ⁇ k y are required to satisfy the following relationship:
  • X 0 is the radius of the imaging area.
  • the imaging area composed of all the meshes obtained by changing the parameters in the above grid expression in the case of satisfying the equations (7) and (8) is the radius in FIG. 1 .
  • Step S32 Calculate a rotation angle and a two-way beam of the mesh in a polar coordinate system to obtain a polar coordinate form of the mesh.
  • the polar form of the grid is expressed as:
  • ⁇ ' represents the rotation angle
  • k' represents the two-way wave number
  • ⁇ ' and k' are both calculated from the k x parameter and the k y parameter of the mesh
  • expressions of ⁇ ' and k' are:
  • Step S33 Obtain a Cartesian coordinate value of the grid whose polar coordinate value matches the polar coordinate value of the second echo signal by using a two-dimensional sinc interpolation method, as a Cartesian coordinate value of the second echo signal And obtaining a third echo signal expressed in the form of Cartesian coordinates of the second echo signal.
  • step S33 specifically refers to selecting a second echo signal having the same polar coordinate value and a mesh represented by a polar coordinate form, and obtaining a right angle of the second echo signal by obtaining a rectangular coordinate value of the mesh.
  • the coordinate value can be used to restore the rectangular coordinate form of the second echo signal according to the rectangular coordinate value, that is, the third echo signal is obtained to complete the conversion of the second echo signal from the polar coordinate form to the rectangular coordinate form.
  • step S33 specifically includes:
  • dk is the sampling interval of k and d ⁇ is the sampling interval of ⁇ .
  • the size of the interpolation point of the two-dimensional sinc interpolation method can be selected according to actual needs, for example, N ⁇ M interpolation points can be used, wherein the value of N ranges from 4 to 32, and an integer M The value ranges from 4 to 32 and N and M are integers.
  • a grid of polar coordinates is created and a rectangular coordinate form of the grid is calculated, and then the second echo signal is corresponding to a grid having the same polar coordinates by using a two-dimensional sinc interpolation method, and the grid can be
  • the Cartesian coordinate value obtains the Cartesian coordinate value of the second echo signal, thereby obtaining the third echo signal represented by the Cartesian coordinates of the second echo signal, and the coordinate conversion process is simple, and the coordinate conversion of the signal can be performed quickly.
  • the step in the embodiment corresponding to FIG. 2 "extracts two-dimensional image information in the three-dimensional image data to obtain a two-dimensional image of the target object", Specifically include:
  • Step S51 Filter the three-dimensional image data along a first orthogonal coordinate direction according to a preset filtering manner.
  • the preset filtering mode may specifically include median filtering or low-pass filtering
  • the first rectangular coordinate direction may be selected according to actual needs, for example, if the target object is to be obtained in two dimensions on the XY plane in FIG. 1 .
  • the first rectangular coordinate direction is the Z-axis direction; if the two-dimensional image of the target object on the XZ plane in FIG. 1 is obtained, the first rectangular coordinate direction is the Y-axis direction; if the target object is to be obtained, In the two-dimensional image on the ZY plane in 1 , the first orthogonal coordinate direction is the X-axis direction.
  • Step S52 Perform maximum value extraction on the filtered three-dimensional image data along the first orthogonal coordinate direction to obtain a maximum value in the first rectangular coordinate direction.
  • step S52 specifically refers to extracting the maximum value of the absolute value in the first rectangular coordinate direction of the three-dimensional image data, that is, extracting the absolute value of the three-dimensional image data
  • Step S53 acquiring a coordinate value of a second rectangular coordinate direction and a coordinate value of a third rectangular coordinate direction corresponding to the maximum value in the three-dimensional image data, as two-dimensional image information of the target object along a preset plane, Obtaining a two-dimensional image of the target object along the predetermined plane.
  • the first rectangular coordinate direction, the second rectangular coordinate direction, and the third rectangular coordinate direction is different and is one of the X-axis direction, the Y-axis direction, and the Z-axis direction in the Cartesian coordinate system shown in FIG. 1 .
  • the preset plane is an XY plane
  • the first orthogonal coordinate direction is a Z-axis direction
  • the second orthogonal coordinate direction and the third orthogonal coordinate direction are respectively one of an X-axis direction and a Y-axis direction.
  • z max represents the coordinate of the numerical value in which the absolute value in the Z-axis direction is the largest in the three-dimensional image data.
  • the preset plane is an XZ plane
  • the first orthogonal coordinate direction is a Y-axis direction
  • the second orthogonal coordinate direction and the third orthogonal coordinate direction are respectively one of an X-axis direction and a Z-axis direction.
  • y max represents the coordinate of the numerical value in which the absolute value in the Y-axis direction is the largest in the three-dimensional image data.
  • the first orthogonal coordinate direction is an X-axis direction
  • the second orthogonal coordinate direction and the third orthogonal coordinate direction are respectively one of a Y-axis direction and a Z-axis direction.
  • x max represents the coordinate of the numerical value in which the absolute value in the X-axis direction is the largest in the three-dimensional image data.
  • the step of “extracting the three-dimensional image information in the three-dimensional image data to obtain a three-dimensional image of the target object” in the embodiment corresponding to FIG. 2 may be implemented by simultaneously or sequentially obtaining a three-dimensional image. All the two-dimensional image information is realized, that is, the two-dimensional image information of the plurality of different two-dimensional images corresponding to the three-dimensional image is acquired simultaneously or sequentially through the above steps S51-53, and then all the two-dimensional image information is combined into three-dimensional image information. , to get a three-dimensional image of the target object.
  • the coordinate information corresponding to the two-dimensional image information of the target object is obtained by means of coordinate extraction, and the two-dimensional image of the target object can be quickly obtained, and the three-dimensional image of the target object can be quickly obtained according to the two-dimensional image of the target object.
  • an embodiment of the present invention provides a close-range microwave imaging system 100 for performing the method steps in the embodiment corresponding to FIG. 2, including:
  • the first echo signal processing module 10 is configured to perform Fourier transform on the echo signal reflected by the target object obtained by rotating the array antenna around the preset rotation axis to obtain a first echo signal, where the first echo signal is obtained.
  • the first echo signal is expressed in polar coordinates;
  • the second echo signal processing module 20 is configured to multiply the first echo signal and the preset reference function to obtain a second echo signal
  • the third echo signal processing module 30 is configured to convert the second echo signal into a rectangular coordinate form by using a preset algorithm to obtain a third echo signal;
  • the three-dimensional image data processing module 40 is configured to perform three-dimensional Fourier transform on the third echo signal to obtain three-dimensional image data of the target object.
  • the close-range microwave imaging system 100 further includes:
  • a two-dimensional image extraction module configured to extract two-dimensional image information along the preset plane in the three-dimensional image data, to obtain a two-dimensional image of the target object along the preset plane, where the preset plane includes three-dimensional rectangular coordinates The XY plane, XZ plane or ZY plane in the system;
  • the three-dimensional image extraction module is configured to extract three-dimensional image information in the three-dimensional image data to obtain a three-dimensional image of the target object.
  • the third echo signal processing module 30 of FIG. 5 includes a structure for performing the method steps in the embodiment corresponding to FIG. 3, including:
  • a grid establishing unit 31 configured to establish a grid having a preset size and a preset sampling interval, the grid being represented in Cartesian coordinates;
  • a mesh polar coordinate calculation unit 32 configured to calculate a rotation angle and a two-way beam of the mesh in a polar coordinate system, to obtain a polar coordinate form of the mesh;
  • a coordinate matching unit 33 configured to obtain a rectangular coordinate value of the grid that matches a polar coordinate value of the second echo signal by using a two-dimensional sinc interpolation method, as the second echo signal
  • the Cartesian coordinate value obtains a third echo signal expressed in the form of Cartesian coordinates of the second echo signal.
  • a grid of polar coordinates is created and a rectangular coordinate form of the grid is calculated, and then the second echo signal is corresponding to a grid having the same polar coordinates by using a two-dimensional sinc interpolation method, and the grid can be
  • the Cartesian coordinate value obtains the Cartesian coordinate value of the second echo signal, thereby obtaining the third echo signal represented by the Cartesian coordinates of the second echo signal, and the coordinate conversion process is simple, and the signal can be quickly applied. Perform coordinate conversion.
  • the two-dimensional image extraction module 50 in the embodiment corresponding to FIG. 5 includes a structure for performing the method steps in the embodiment corresponding to FIG. 4, including :
  • the first direction filtering unit 51 is configured to filter the three-dimensional image data along a first orthogonal coordinate direction according to a preset filtering manner
  • a first direction maximum value extracting unit 52 configured to perform maximum value extraction on the filtered three-dimensional image data along the first rectangular coordinate direction to obtain a maximum value in a first rectangular coordinate direction;
  • the two-dimensional image acquisition unit 53 is configured to acquire a coordinate value of a second rectangular coordinate direction and a coordinate value of a third rectangular coordinate direction corresponding to the maximum value in the three-dimensional image data, as the target object along a preset plane Two-dimensional image information to obtain a two-dimensional image of the target object along the predetermined plane.
  • the three-dimensional image extraction module in the embodiment corresponding to FIG. 5 includes a two-dimensional image extraction module for simultaneously or sequentially extracting a plurality of different two-dimensional images corresponding to the three-dimensional image by using the two-dimensional image extraction module.
  • the two-dimensional image information is then combined into all three-dimensional image information to obtain a three-dimensional image of the target object.
  • the echo signals reflected by the target object obtained by rotating the array antenna around the preset rotation axis in the frequency domain are subjected to Fourier transform, reference function multiplication, and coordinate conversion processing, and finally the echo signals can be formed by polar coordinates. It is converted into a rectangular coordinate form, so that the three-dimensional image data of the target object can be quickly obtained, and the target object can be quickly imaged, the data processing amount is small, the imaging precision is high, and it is easy to implement, and is suitable for widespread use.
  • the modules or units in all the embodiments of the present invention may be implemented by a general-purpose integrated circuit, such as a CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit).
  • a CPU Central Processing Unit
  • ASIC Application Specific Integrated Circuit
  • Modules or units in the apparatus of the embodiments of the present invention may be combined, divided, and deleted according to actual needs.
  • the storage medium may be a magnetic disk, an optical disk, or a read-only memory (ROM). Or random access memory (RAM), etc.

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Abstract

一种近景微波成像方法及系统，其中，近景微波成像方法包括：对阵列天线绕预设转轴旋转所获取的目标物体反射的回波信号作预设转轴向的傅里叶变换，得到第一回波信号，该第一回波信号以极坐标形式表示（S10）；对第一回波信号和预设参考函数进行乘运算，得到第二回波信号（S20）；通过预设算法将第二回波信号转换为直角坐标形式，得到第三回波信号（S30）；对第三回波信号作三维傅里叶变换，得到目标物体的三维图像数据（S40）。该方法可以快速的得到目标物体的三维图像数据，实现目标物体的快速成像，数据处理量小、成像精度高且易于实现。

Description

一种近景微波成像方法及系统 技术领域
本发明实施例属于近景微波成像技术领域，尤其涉及一种近景微波成像方法及系统。
背景技术
近景微波成像技术采用阵列天线绕特定转轴旋转形成曲面扫描面，以主动发射微波波段电磁波的方式对物体进行扫描成像，因其能够穿透物体表面而检测藏匿于物体内部的金属或非金属违禁品，且由于其具有辐射剂量小、属于非电离辐射等特点，广泛应用于安检系统，用于执行人体安全检查任务。
然而，近景微波成像技术由于扫描路径弯曲，数据处理量大，成像精度要求较高，而不易于实施，难以广泛推广使用。
发明内容
本发明实施例提供一种近景微波成像方法及系统，旨在解决近景微波成像技术中，由于扫描路径弯曲，数据处理量大，成像精度要求较高，而不易于实施，难以广泛推广使用的问题。
本发明实施例一方面提供一种近景微波成像方法，其包括：
对阵列天线绕预设转轴旋转所获取的目标物体反射的回波信号作预设转轴向的傅里叶变换，得到第一回波信号，所述第一回波信号以极坐标形式表示；
对所述第一回波信号和预设参考函数进行乘运算，得到第二回波信号；
通过预设算法将所述第二回波信号转换为直角坐标形式，得到第三回波信号；
对所述第三回波信号作三维傅里叶变换，得到所述目标物体的三维图像数据。
本发明实施例另一方面还提供一种近景微波成像系统，其包括：
第一回波信号处理模块，用于对阵列天线绕预设转轴旋转所获取的目标物体反射的回波信号作预设转轴向的傅里叶变换，得到第一回波信号，所述第一回波信号以极坐标形式表示；
第二回波信号处理模块，对所述第一回波信号和预设参考函数进行乘运算，得到第二回波信号；
第三回波信号处理模块，通过预设算法将所述第二回波信号转换为直角坐标形式，得到第三回波信号；
三维图像数据处理模块，对所述第三回波信号作三维傅里叶变换，得到所述目标物体的三维图像数据。
本发明实施例通过在频域对阵列天线绕预设转轴旋转所获取的目标物体反射的回波信号进行傅里叶变换、参考函数相乘和坐标转换处理，最终可以将回波信号由极坐标形式转换为直角坐标形式，从而可以快速的得到目标物体的三维图像数据，实现目标物体的快速成像，数据处理量小、成像精度高且易于实现，适于广泛推广使用。
附图说明
为了更清楚地说明本发明实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本发明的一个实施例提供的笛卡尔坐标系下的柱面扫描系统的示意图；
图2是本发明的一个实施例提供的近景微波成像方法的流程框图；
图3是本发明的一个实施例提供图2中步骤S30的流程框图；
图4是本发明的另一个实施例提供的近景微波成像方法的流程框图；
图5是本发明的一个实施例提供的近景微波成像系统的结构框图；
图6是本发明的一个实施例提供的图5中第三回波信号处理模块的结构框图；
图7是本发明的另一个实施例提供的近景微波成像系统的结构框图。
具体实施方式
为了使本技术领域的人员更好地理解本发明方案，下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚地描述，显然，所描述的实施例是本发明一部分的实施例，而不是全部的实施例。基于本发明中的实施例，本 领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都应当属于本发明保护的范围。
本发明的说明书和权利要求书及上述附图中的术语“包括”以及它们任何变形，意图在于覆盖不排他的包含。例如包含一系列步骤或单元的过程、方法或系统、产品或设备没有限定于已列出的步骤或模块，而是可选地还包括没有列出的步骤或模块，或可选地还包括对于这些过程、方法、产品或设备固有的其它步骤或模块。
本发明所有实施例基于近景微波成像系统实现，该系统由线性排列的预设个数的天线组成的阵列天线、信号收发设备和机械旋转设备和信号处理设备。
在具体应用中，信号处理设备可以采用图形处理器(Graphics Processing Unit，GPU)。
机械旋转设备控制阵列天线旋转，信号收发设备通过阵列天线在旋转过程中发射信号并接收待成像的目标物体反射的回波信号，信号收发设备将回波信号发送给信号处理设备处理为成像结果，实现对目标物体上各采样点的扫描成像。根据阵列天线旋转过程中的等效相位位置所形成的扫描面的形状，可以将近景微波成像系统分为弧面扫描系统或柱面扫描系统。
以下着重介绍柱面扫描系统的工作原理：
如图1所示，设定平行于水平面的X轴，设定与X轴正交且处于同一平面的Y轴，设定位于垂直于水平面的平面中Z轴，设定X轴、Y轴和Z轴相交于一点O，以O为原点建立包括X轴、Y轴和Z轴的笛卡尔坐标系X-Y-Z-O。
多个天线在垂直于水平面的Z轴方向上组成阵列天线，阵列天线距柱面扫描系统的几何中轴线(即预设转轴)的距离为R(即天线阵列的旋转半径为R)，该阵列天线绕几何中轴线旋转一周(即360°)后，等效形成在柱面上分布的等方位角间隔、等高度间隔的多个等效天线位置，该等效天线位置称为天线的等效相位中心，通过获取在所有等效天线的等效相位中心位置所采集到的由目标物体反射回来的回波信号来实现对目标物体的三维成像。
如图2所示，本发明的一个实施例提供的一种近距离微波成像方法，其包括：
步骤S10：对阵列天线绕预设转轴旋转所获取的目标物体反射的回波信号作预设转轴向的傅里叶变换，得到第一回波信号，所述第一回波信号以极坐标形式 表示。
在具体应用中，柱面扫描系统的阵列天线可以垂直于水平面放置、平行于水平面放置或者倾斜放置，具体可以根据实际需要进行选择；傅里叶变换具体可以选用并行快速傅里叶变换，即可以同时对在每个等效天线的等效相位中心位置处采集到的回波信号进行处理，以加快数据处理速度。
本实施例基于图1所示的柱面扫描系统实现，即阵列天线垂直于水平面放置，预设转轴与图1中的Z轴重合，预设转轴向即为Z轴方向。步骤S10中的回波信号包括在所有等效天线的等效相位中心位置所采集到的由目标物体上的多个采样点所反射回来的反射信号。
在一个实施例中，定义回波信号的极坐标表达形式为：
S0(θ,k,z)    (1)
其中，θ为阵列天线绕预设转轴旋转的旋转角度，k＝4πf/C为相对于预设转轴的双程波数，f为阵列天线的发射信号的频率，C为光速，z为回波信号在预设转轴向上的采集高度(即回波信号是在坐标为z的等效天线的等效相位中心位置采集到的)。
在一个实施例中，所述第一回波信号的极坐标表达形式为：
S1(θ,k,kz)    (2)
其中，kz为预设转轴向上坐标为z的等效天线所对应的双程波数。
在具体应用中，式(1)和式(2)中各变量的取值不同即代表与不同等效天线对应的信号。
步骤S20：对所述第一回波信号和预设参考函数进行乘运算，得到第二回波信号。
在具体应用中，采用预设参考函数与第一回波信号进行乘运算是为了对第一回波信号进行相位补偿。
在一个实施例中，所述第二回波信号的表达式为：
S2(θ,k,kz)＝S1(θ,k,kz)·H(f)    (3)
其中，H(f)为所述预设参考函数的表达式，
Figure PCTCN2017100397-appb-000001
R为 阵列天线绕预设转轴旋转的旋转半径(参见图1中的R)；式(3)中各变量的取值不同即代表与不同等效天线对应的信号。
步骤S30：通过预设算法将所述第二回波信号转换为直角坐标形式，得到第三回波信号。
在具体应用中，第二回波信号以极坐标形式表示，将第二回波信号转换为直角坐标形式即是将在每个等效天线的等效相位中心位置处采集到的反射信号对应到图1所示的笛卡尔坐标系中成像区域上的每个坐标位置。
在一个实施例中，所述第三回波信号的直角坐标表达形式为：
S3(kx,ky,kz)    (4)
其中，kx为X轴方向上坐标为x的等效天线对应的双程波数，ky为Y轴方向上坐标为y的天线对应的双程波数；式(4)中各变量的取值不同即代表与不同等效天线对应的信号。
在具体应用中，预设算法可以是插值算法，例如，最临近插值算法、线性插值算法、极坐标插值算法或样条插值法等。
步骤S40：对所述第三回波信号作三维傅里叶变换，得到所述目标物体的三维图像数据。
在一个实施例中，所述目标物体的三维图像数据的表达式为：
S4(x,y,z)    (5)
其中，x为等效天线在X轴方向上的坐标，y为等效天线在Y轴方向上的坐标，z为等效天线在Z轴方向上的坐标。
在一个实施例中，步骤S40之后还包括：
提取所述三维图像数据中沿预设平面的二维图像信息，得到所述目标物体沿所述预设平面的二维图像，所述预设平面包括三维直角坐标系中的X-Y平面、X-Z平面或Z-Y平面；
或者，提取所述三维图像数据中的三维图像信息，得到所述目标物体的三维图像。
在具体应用中，三维直角坐标系即为图1所示的笛卡尔坐标系。
在具体应用中，由于目标物体上各采样点的回波信号均对应由直角坐标形式 表示的三维图像数据中的一组直角坐标数值，因此可以根据实际需要从三维图像数据中提取目标物体上某一个二维区域中各采样点所对应的直角坐标数值，即可得到该二维区域的二维图像信息，同理，只需要提取目标物体上某个三维区域中各采样点所对应的直角坐标数值，即可得到该三维区域的三维图像信息。
本实施例通过在频域对阵列天线绕预设转轴旋转所获取的目标物体反射的回波信号进行傅里叶变换、参考函数相乘和坐标转换处理，最终可以将回波信号由极坐标形式转换为直角坐标形式，从而可以快速的得到目标物体的三维图像数据，实现目标物体的快速成像，数据处理量小、成像精度高且易于实现，适于广泛推广使用。
如图3所示，在本发明的一个实施例中，图2所对应的实施例中的步骤S30具体包括：
步骤S31：建立具有预设尺寸和预设采样间隔的网格，所述网格以直角坐标形式表示。
在一个实施例中，所述网格的表达式为：
(kx,ky)    (6)
在具体应用中，式(6)中的各变量的取值不同即代表在直角坐标系中坐标不同的网格；预设尺寸即是指每个网格的面积大小，可以根据实际需要进行设置，只要保证每个网格的最大长度和宽度均大于[-4πfmax/C,4πfmax/C]范围即可，即(kx,ky)中的kx和ky均需满足以下关系式：
Figure PCTCN2017100397-appb-000002
其中，fmax为发射信号的频率的最大值。
在具体应用中，预设采样间隔即是指相邻两个网格之间的距离，即相邻两个网格的几何中心点之间的直线距离，沿X轴方向排列的相邻两个网格之间的距离设定为Δkx、沿X轴方向排列的相邻两个网格之间的距离设定为Δky，Δkx和Δky都需满足以下关系式：
Figure PCTCN2017100397-appb-000003
其中，X0为成像区域的半径。
如图1所示，在具体应用中，在满足式(7)和(8)的情况下改变上述网格表达式中的参数所得到的所有网格所组成的成像区域即为图1中半径为X0的柱面成像区域。
步骤S32：计算所述网格在极坐标系中的旋转角度和双程波束，得到所述网格的极坐标形式。
在一个实施例中，所述网格的极坐标形式表示为：
(θ′,k′)    (9)
其中，θ′表示旋转角度，k′表示双程波数，θ′和k′均由所述网格的kx参数和ky参数计算得到，θ′和k′的表达式为：
Figure PCTCN2017100397-appb-000004
其中，j代表虚数，函数angle()代表对复数的相位角求解操作。
步骤S33：通过二维sinc插值法，获取极坐标数值与所述第二回波信号的极坐标数值相匹配的所述网格的直角坐标数值，作为所述第二回波信号的直角坐标数值，得到以所述第二回波信号的直角坐标形式表示的第三回波信号。
在具体应用中，步骤S33具体是指选取极坐标数值相同的第二回波信号和采用极坐标形式表示的网格，通过获取该网格的直角坐标数值即可得到第二回波信号的直角坐标数值，从而可以根据直角坐标数值还原第二回波信号的直角坐标形式，即得到第三回波信号，以完成第二回波信号从极坐标形式到直角坐标形式的转换。
在一个实施例中，步骤S33具体包括：
根据插值公式
Figure PCTCN2017100397-appb-000005
计 算得到第三回波信号S3(kx,ky,kz)；
其中，dk为k的采样间隔，dθ为θ的采样间隔。
在具体应用中，二维sinc插值法的插值点的大小可以根据实际需要进行选择，例如，可以采用N×M个插值点进行，其中，N的取值范围为4～32的一个整数、M的取值范围为4～32且N和M均为整数。
本实施例通过建立极坐标形式的网格并计算得到网格的直角坐标形式，然后采用二维sinc插值法将第二回波信号对应到与其极坐标相同的网格，即可通过网格的直角坐标数值得到第二回波信号的直角坐标数值，从而得到以第二回波信号的直角坐标形式表示的第三回波信号，坐标转换过程简单，可以快速的对信号进行坐标转换。
如图4所述，在本发明的一个实施例中，图2所对应的实施例中的步骤“提取所述三维图像数据中的二维图像信息，得到所述目标物体的二维图像”，具体包括：
步骤S51：根据预设滤波方式，沿第一直角坐标方向对所述三维图像数据进行滤波。
在具体应用中，预设滤波方式具体可以包括中值滤波或低通滤波，第一直角坐标方向可以根据实际需要进行选择，例如，若想要得到目标物体在图1中X-Y平面上的二维图像，则第一直角坐标方向为Z轴方向；若想要得到目标物体在图1中X-Z平面上的二维图像，则第一直角坐标方向为Y轴方向；若想要得到目标物体在图1中Z-Y平面上的二维图像，则第一直角坐标方向为X轴方向。
步骤S52：沿所述第一直角坐标方向对滤波后的所述三维图像数据进行最大值提取，得到第一直角坐标方向上的最大值。
在具体应用中，步骤S52具体是指对三维图像数据中第一直角坐标方向上绝对值最大的数值进行提取，即提取三维图像数据的绝对值|S4(x,y,z)|沿第一直角坐标方向的最大数值。
步骤S53：获取所述三维图像数据中所述最大值所对应的第二直角坐标方向的坐标值和第三直角坐标方向的坐标值，作为所述目标物体沿预设平面的二维图像信息，以得到所述目标物体沿所述预设平面的二维图像。
在具体应用中，第一直角坐标方向、第二直角坐标方向和第三直角坐标方向 各不相同且分别为图1所示的直角坐标系中的X轴方向、Y轴方向和Z轴方向中的一个。
在一个实施例中，若预设平面为X-Y平面，则所述第一直角坐标方向为Z轴方向，第二直角坐标方向和第三直角坐标方向分别为X轴方向和Y轴方向中的一个，所述二维图像的表达式为：
S5(x,y)＝S4(x,y,z＝zmax)    (11)
其中，zmax表示三维图像数据中Z轴方向上绝对值最大的数值的坐标。
在一个实施例中，若预设平面为X-Z平面，则所述第一直角坐标方向为Y轴方向，第二直角坐标方向和第三直角坐标方向分别为X轴方向和Z轴方向中的一个，所述二维图像的表达式为：
S6(x,z)＝S4(x,y＝ymax,z)    (12)
其中，ymax表示三维图像数据中Y轴方向上绝对值最大的数值的坐标。
在一个实施例中，若预设平面为Y-Z平面，则所述第一直角坐标方向为X轴方向，第二直角坐标方向和第三直角坐标方向分别为Y轴方向和Z轴方向中的一个，所述二维图像的表达式为：
S7(y,z)＝S4(x＝xmax,y,z)    (13)
其中，xmax表示三维图像数据中X轴方向上绝对值最大的数值的坐标。
在具体应用中，图2所对应的实施例中的步骤“提取所述三维图像数据中的三维图像信息，得到所述目标物体的三维图像”的实现方法可以通过同时或者依次得到三维图像所包括的所有二维图像信息实现，即通过上述的步骤S51～53同时或依次获取三维图像所对应的多个不同的二维图像的二维图像信息，然后将所有二维图像信息组合成三维图像信息，得到目标物体的三维图像。
本实施例通过坐标提取的方式获得目标物体的二维图像信息所对应的坐标信息，可以快速的获得目标物体的二维图像，进而可以根据目标物体的二维图像快速的获得目标物体的三维图像。
如图5所示，本发明的一个实施例提供一种近景微波成像系统100用于执行图2所对应的实施例中的方法步骤，其包括：
第一回波信号处理模块10，用于对阵列天线绕预设转轴旋转所获取的目标物体反射的回波信号作预设转轴向的傅里叶变换，得到第一回波信号，所述第一回波信号以极坐标形式表示；
第二回波信号处理模块20，用于对所述第一回波信号和预设参考函数进行乘运算，得到第二回波信号；
第三回波信号处理模块30，用于通过预设算法将所述第二回波信号转换为直角坐标形式，得到第三回波信号；
三维图像数据处理模块40，用于对所述第三回波信号作三维傅里叶变换，得到所述目标物体的三维图像数据。
在一个实施例中，近景微波成像系统100还包括：
二维图像提取模块，用于提取所述三维图像数据中沿预设平面的二维图像信息，得到所述目标物体沿所述预设平面的二维图像，所述预设平面包括三维直角坐标系中的X-Y平面、X-Z平面或Z-Y平面；
三维图像提取模块，用于提取所述三维图像数据中的三维图像信息，得到所述目标物体的三维图像。
如图6所示，在本发明的一个实施例中，图5中的第三回波信号处理模块30包括用于执行图3所对应的实施例中的方法步骤的结构，其包括：
网格建立单元31，用于建立具有预设尺寸和预设采样间隔的网格，所述网格以直角坐标形式表示；
网格极坐标计算单元32，用于计算所述网格在极坐标系中的旋转角度和双程波束，得到所述网格的极坐标形式；
坐标匹配单元33，用于通过二维sinc插值法，获取极坐标数值与所述第二回波信号的极坐标数值相匹配的所述网格的直角坐标数值，作为所述第二回波信号的直角坐标值，得到以所述第二回波信号的直角坐标形式表示的第三回波信号。
本实施例通过建立极坐标形式的网格并计算得到网格的直角坐标形式，然后采用二维sinc插值法将第二回波信号对应到与其极坐标相同的网格，即可通过网格的直角坐标数值得到第二回波信号的直角坐标数值，从而得到以第二回波信号的直角坐标形式表示的第三回波信号，坐标转换过程简单，可以快速的对信号 进行坐标转换。
如图7所示，在本发明的一个实施例中，图5所对应的实施例中的二维图像提取模块50包括用于执行图4所对应的实施例中的方法步骤的结构，其包括：
第一方向滤波单元51，用于根据预设滤波方式，沿第一直角坐标方向对所述三维图像数据进行滤波；
第一方向最大值提取单元52，用于沿所述第一直角坐标方向对滤波后的所述三维图像数据进行最大值提取，得到第一直角坐标方向上的最大值；
二维图像获取单元53，用于获取所述三维图像数据中所述最大值所对应的第二直角坐标方向的坐标值和第三直角坐标方向的坐标值，作为所述目标物体沿预设平面的二维图像信息，以得到所述目标物体沿所述预设平面的二维图像。
在一个实施例中，图5所对应的实施例中的三维图像提取模块包括二维图像提取模块，用于通过二维图像提取模块同时或依次提取三维图像所对应的多个不同的二维图像的二维图像信息，然后将所有二维图像信息组合成三维图像信息，得到目标物体的三维图像。
本实施例通过在频域对阵列天线绕预设转轴旋转所获取的目标物体反射的回波信号进行傅里叶变换、参考函数相乘和坐标转换处理，最终可以将回波信号由极坐标形式转换为直角坐标形式，从而可以快速的得到目标物体的三维图像数据，实现目标物体的快速成像，数据处理量小、成像精度高且易于实现，适于广泛推广使用。
本发明所有实施例中的模块或单元，可以通过通用集成电路，例如CPU(Central Processing Unit，中央处理器)，或通过ASIC(Application Specific Integrated Circuit，专用集成电路)来实现。
本发明实施例方法中的步骤可以根据实际需要进行顺序调整、合并和删减。
本发明实施例装置中的模块或单元可以根据实际需要进行合并、划分和删减。
本领域普通技术人员可以理解实现上述实施例方法中的全部或部分流程，是可以通过计算机程序来指令相关的硬件来完成，所述的程序可存储于一计算机可读取存储介质中，该程序在执行时，可包括如上述各方法的实施例的流程。其中，所述的存储介质可为磁碟、光盘、只读存储记忆体(Read-Only Memory，ROM) 或随机存储记忆体(Random Access Memory，RAM)等。
以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (10)

  1. 一种近景微波成像方法，其特征在于，所述近景微波成像方法包括：
    对阵列天线绕预设转轴旋转所获取的目标物体反射的回波信号作预设转轴向的傅里叶变换，得到第一回波信号，所述第一回波信号以极坐标形式表示；
    对所述第一回波信号和预设参考函数进行乘运算，得到第二回波信号；
    通过预设算法将所述第二回波信号转换为直角坐标形式，得到第三回波信号；
    对所述第三回波信号作三维傅里叶变换，得到所述目标物体的三维图像数据。
  2. 如权利要求1所述的近景微波成像方法，其特征在于，所述通过预设算法将所述第二回波信号转换为直角坐标形式，得到第三回波信号包括：
    建立具有预设尺寸和预设采样间隔的网格，所述网格以直角坐标形式表示；
    计算所述网格在极坐标系中的旋转角度和双程波束，得到所述网格的极坐标形式；
    通过二维sinc插值法，获取极坐标数值与所述第二回波信号的极坐标数值相匹配的所述网格的直角坐标数值，作为所述第二回波信号的直角坐标数值，得到以所述第二回波信号的直角坐标形式表示的第三回波信号。
  3. 如权利要求1所述的近景微波成像方法，其特征在于，所述近景微波成像方法还包括：
    提取所述三维图像数据中沿预设平面的二维图像信息，得到所述目标物体沿所述预设平面的二维图像，所述预设平面包括三维直角坐标系中的X-Y平面、X-Z平面或Z-Y平面。
  4. 如权利要求3所述的近景微波成像方法，其特征在于，所述提取所述三维图像数据中沿预设平面的二维图像信息，得到所述目标物体沿所述预设平面的二维图像，包括：
    根据预设滤波方式，沿第一直角坐标方向对所述三维图像数据进行滤波；
    沿所述第一直角坐标方向对滤波后的所述三维图像数据进行最大值提取，得到第一直角坐标方向上的最大值；
    获取所述三维图像数据中所述最大值所对应的第二直角坐标方向的坐标值 和第三直角坐标方向的坐标值，作为所述目标物体沿预设平面的二维图像信息，以得到所述目标物体沿所述预设平面的二维图像。
  5. 如权利要求1所述的近景微波成像方法，其特征在于，所述近景微波成像方法还包括：
    提取所述三维图像数据中的三维图像信息，得到所述目标物体的三维图像。
  6. 一种近景微波成像系统，其特征在于，所述近景微波成像系统包括：
    第一回波信号处理模块，用于对阵列天线绕预设转轴旋转所获取的目标物体反射的回波信号作预设转轴向的傅里叶变换，得到第一回波信号，所述第一回波信号以极坐标形式表示；
    第二回波信号处理模块，用于对所述第一回波信号和预设参考函数进行乘运算，得到第二回波信号；
    第三回波信号处理模块，用于通过预设算法将所述第二回波信号转换为直角坐标形式，得到第三回波信号；
    三维图像数据处理模块，用于对所述第三回波信号作三维傅里叶变换，得到所述目标物体的三维图像数据。
  7. 如权利要求6所述的近景微波成像系统，其特征在于，所述第三回波信号处理模块包括：
    网格建立单元，用于建立具有预设尺寸和预设采样间隔的网格，所述网格以直角坐标形式表示；
    网格极坐标计算单元，用于计算所述网格在极坐标系中的旋转角度和双程波束，得到所述网格的极坐标形式；
    坐标匹配单元，用于通过二维sinc插值法，获取极坐标数值与所述第二回波信号的极坐标数值相匹配的所述网格的直角坐标数值，作为所述第二回波信号的直角坐标值，得到以所述第二回波信号的直角坐标形式表示的第三回波信号。
  8. 如权利要求6所述的近景微波成像系统，其特征在于，所述近景微波成像系统还包括：
    二维图像提取模块，用于提取所述三维图像数据中沿预设平面的二维图像信息，得到所述目标物体沿所述预设平面的二维图像，所述预设平面包括三维直角坐标系中的X-Y平面、X-Z平面或Z-Y平面。
  9. 如权利要求8所述的近景微波成像系统，其特征在于，所述二维图像提取模块包括：
    第一方向滤波单元，用于根据预设滤波方式，沿第一直角坐标方向对所述三维图像数据进行滤波；
    第一方向最大值提取单元，用于沿所述第一直角坐标方向对滤波后的所述三维图像数据进行最大值提取，得到第一直角坐标方向上的最大值；
    二维图像获取单元，用于获取所述三维图像数据中所述最大值所对应的第二直角坐标方向的坐标值和第三直角坐标方向的坐标值，作为所述目标物体沿预设平面的二维图像信息，以得到所述目标物体沿所述预设平面的二维图像。
  10. 如权利要求6所述的近景微波成像系统，其特征在于，所述近景微波成像系统还包括：
    三维图像提取模块，用于提取所述三维图像数据中的三维图像信息，得到所述目标物体的三维图像。
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