CN114994667A - Rapid imaging method of semi-holographic array - Google Patents

Rapid imaging method of semi-holographic array Download PDF

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CN114994667A
CN114994667A CN202210572821.7A CN202210572821A CN114994667A CN 114994667 A CN114994667 A CN 114994667A CN 202210572821 A CN202210572821 A CN 202210572821A CN 114994667 A CN114994667 A CN 114994667A
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array
imaging
scanning
weighting
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张继龙
张继康
王栋
姚广锋
杨洲
赵春秋
俞智雯
张梓青
张鑫
张艺恒
张云生
宋雨花
俞晓琳
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Suzhou Weimo Electronic Information Technology Co ltd
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    • 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
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    • 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
    • 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
    • G01S13/9021—SAR image post-processing techniques
    • 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
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    • 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
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
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    • G01S15/8906—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
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    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/88—Sonar systems specially adapted for specific applications
    • G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
    • G01S15/8906—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
    • G01S15/8977—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques using special techniques for image reconstruction, e.g. FFT, geometrical transformations, spatial deconvolution, time deconvolution
    • 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
    • G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
    • G01S15/88—Sonar systems specially adapted for specific applications
    • G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
    • G01S15/8906—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
    • G01S15/8997—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques using synthetic aperture techniques
    • 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
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
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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
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
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    • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
    • G01S17/90—Lidar systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques
    • 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
    • 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
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/4802—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • 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
    • G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
    • G01S7/539—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section

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Abstract

The invention relates to the technical fields of optical imaging, microwave imaging, radar detection, sonar, ultrasonic imaging, target detection based on media such as sound, light, electricity, magnetism and the like, imaging identification and wireless communication, in particular to a quick imaging method of a semi-holographic array and application thereof in the fields. The method comprises the steps of determining two mutually different scanning attribute parameter values of a semi-holographic array, sequentially carrying out focusing phase weighting, scanning phase weighting and amplitude weighting on array signals according to the two mutually different scanning attribute parameter values, carrying out imaging processing by adopting a high-efficiency parallel algorithm, and carrying out coordinate inversion on an image field. The method is suitable for the quick imaging of the semi-holographic array with the mixed array attribute, has the advantages of small operand, low hardware cost, quick imaging speed and the like, and can be compatible with the imaging of far and near different distances.

Description

Rapid imaging method of semi-holographic array
Technical Field
The invention relates to the technical fields of optical imaging, microwave imaging, radar detection, sonar, ultrasonic imaging, target detection based on media such as sound, light, electricity, magnetism and the like, imaging identification and wireless communication, in particular to a quick imaging method of a semi-holographic array and application thereof in the fields.
Background
In some semi-holographic array systems, the horizontal direction (or vertical direction) of the array simultaneously receives and transmits signals, and the other direction sequentially transmits and receives signals, and in this case, the two-dimensional array adopts different scanning systems in different directions, which is different from a conventional array system in which all the cells simultaneously receive and transmit signals, and is different from a holographic array system in which all the cells sequentially receive and transmit signals. For example, when a one-dimensional linear array that simultaneously transmits and receives signals is used to perform planar scanning imaging, the semi-holographic array is formed. In a semi-holographic array system, a traditional digital beam synthesis technology and an existing holographic imaging technology cannot be used, but the hardware cost of the semi-holographic array system is relatively low, and the imaging time can be greatly shortened, so that the semi-holographic array system has high system response speed and has great economic value in practical application.
The present inventors have developed a series of related fast imaging techniques, such as an array fast imaging method and applications thereof (chinese patent application No. 2021111811772), a digital holography fast imaging method (chinese patent application No. 202111123894X), a fast imaging method suitable for passive imaging and active imaging (chinese patent application No. 202111123446X), and the like.
It should be noted that in the above "fast imaging method suitable for passive imaging and active imaging", we provide a fast imaging method compatible with multiple technical systems such as active, passive, holographic, etc., where phi F Weighting coefficients for focus phase:
Figure BDA0003660919430000011
wherein R is a target slant range, eta is an array attribute parameter, and eta is 1 for a passive imaging system, a semi-active imaging system and a conventional phased array system; for an active holographic imaging system, let η be 2.
However, in the above-mentioned patent application, only 1 array property parameter η is involved, giving a fast imaging implementation of a two-dimensional array with a single array property. However, when the two-dimensional array has different array attributes in different directions, the above-mentioned fast imaging method cannot achieve effective imaging.
Therefore, for the semi-holographic array system, developing an imaging method with good compatibility and excellent imaging effect has great application value and urgent practical significance.
Disclosure of Invention
In order to solve the above problems, we have conducted intensive system research on a semi-holographic imaging system and have obtained a new feasible fast imaging method.
The semi-holographic imaging system has two different array attribute parameters eta x And η y When the array units in a certain dimension direction simultaneously transmit and receive signals, the corresponding array attribute parameter value is 1, and when the array units in the other dimension direction sequentially transmit and receive signals, the corresponding array attribute parameter value is 2.
FIG. 1 illustrates a semi-holographic imaging system, establishing a coordinate system of the semi-holographic imaging system, wherein: p is the target, Q is the image of the target, the array is located on a plane with z equal to 0, and X denotes the transmit-receive antenna element.
For a propagation phase shift phi of the target to the array element 1 Equivalent lens phase shift phi L And propagation phase shift phi of array elements to the imaging plane 2 The decomposition is performed according to the variables x and y, obtaining the component associated with the array direction:
Figure BDA0003660919430000021
wherein the content of the first and second substances,
Figure BDA0003660919430000022
is wave number, lambda is wavelength, U is object distance, i.e. distance from the target to the array plane, V is image distance, i.e. distance from the image plane to the array plane, and F is lens focal length; (ζ, ξ) are target coordinates, (x, y) are array element coordinates, and (δ, σ) are image point coordinates.
In order to facilitate separation in two dimensions of the array, the following formula is used for imaging processing:
Figure BDA0003660919430000031
wherein the content of the first and second substances,
Figure BDA0003660919430000032
in order to be the image field distribution,
Figure BDA0003660919430000033
for the target scatter signal, j is the imaginary unit and e is the Euler constant.
The formula is simplified and finished to obtain:
Figure BDA0003660919430000034
wherein the content of the first and second substances,
Figure BDA0003660919430000035
Figure BDA0003660919430000036
when the imaging condition is satisfied have
Figure BDA0003660919430000037
At this time there is phi x ＝0、φ y Substituting 0, simplifying the formula:
Figure BDA0003660919430000038
studies have shown that the larger the wavefront scale, the closer the double integration result on the right side of the above equation is to the morphology of Dirac function (Dirac), and the following approximately linear relationship exists between the obtained image and the source field:
Figure BDA0003660919430000039
the above equation shows that the semi-holographic imaging system now achieves near linear imaging of the target.
For an actual discrete array system, assuming that a target signal received by an array is E, the following processing needs to be performed on the signal received by the array during imaging:
Figure BDA00036609194300000310
wherein the content of the first and second substances,
Figure BDA00036609194300000311
for the target signal received by the array unit, A mn And (3) obtaining an amplitude weighting coefficient of the array units, wherein M is the number of the array units in the x direction, and N is the number of the array units in the y direction by expanding and sorting the above formula:
Figure BDA0003660919430000041
wherein the content of the first and second substances,
Figure BDA0003660919430000042
Figure BDA0003660919430000043
when the condition is satisfied
Figure BDA0003660919430000044
x m ＝x 0 +mΔ x 、y n ＝y 0 +nΔ y Sometimes:
Figure BDA0003660919430000045
wherein m and n are respectively the serial numbers of the array unit in the x direction and the y direction, (x) 0 ，y 0 ) Is the coordinates of the starting cell of the array,
Figure BDA0003660919430000046
Δ x 、Δ y the array unit pitches in the x direction and the y direction are respectively.
The right coefficient of the above formula satisfies
Figure BDA0003660919430000047
The spatial fluctuation characteristic of an image field is reflected, and the influence on imaging is basically avoided and can be ignored. The summation operation can be quickly solved by two-dimensional inverse fast fourier transform, and then the image field calculation formula is:
Figure BDA0003660919430000048
wherein the content of the first and second substances,
Figure BDA0003660919430000049
for the finally obtained spectral domain image, the IFFT represents a two-dimensional inverse fast fourier transform.
Based on the above knowledge, the invention provides a fast imaging method of a semi-holographic array, which is based on the lens imaging principle, and obtains the image field distribution corresponding to the target by weighting the amplitude and the phase of a unit signal and adopting an efficient parallel algorithm according to the target signal received by an antenna array.
Specifically, the method for rapidly imaging the semi-holographic array comprises the following steps:
the method comprises the following steps: determining two mutually different scanning attribute parameter values of the semi-holographic array;
step two: carrying out focusing phase weighting on the array signals according to the two mutually different scanning attribute parameter values;
step three: carrying out scanning phase weighting on the array signals according to the two mutually different scanning attribute parameter values;
step four: amplitude weighting the array signals;
step five: performing rapid imaging processing on the array signals by adopting an efficient parallel algorithm;
step six: and performing coordinate inversion on the image field according to the two different scanning attribute parameter values.
Further, the determining two mutually different scanning attribute parameter values of the semi-holographic array in the first step of the fast imaging method of the present invention includes:
in a semi-holographic array system, the scanning attribute parameters eta of the array in different directions x 、η y The values of (A) are different;
if the array unit in a certain direction of the array simultaneously transmits and receives the target signal, the scanning attribute parameter eta of the direction is selected x Or η y Has a value of 1;
if the array units in a certain direction of the array sequentially transmit and receive target signals, selecting a scanning attribute parameter eta of the direction x Or η y The value of (2).
Further, in the second step of the fast imaging method of the present invention, the focusing phase weighting is performed on the array signal according to the two mutually different scan attribute parameter values, and the calculation formula is as follows:
Figure BDA0003660919430000051
wherein s is 1 For focusing the phase-weighted array signal, s 0 Is the array echo signal, e is the Euler constant, j is the imaginary unit,
Figure BDA0003660919430000052
for the focus phase weights in the x-direction of the array,
Figure BDA0003660919430000053
a focus phase weight for the y direction of the array;
wherein the focusing phase weighted value of the x direction of the array
Figure BDA0003660919430000054
The calculation method of (2) is as follows:
Figure BDA0003660919430000055
focusing phase weights for y-direction of array
Figure BDA0003660919430000056
The calculation method of (2) is as follows:
Figure BDA0003660919430000057
wherein R is the target slant distance, namely the distance from the target to the center of the array,
Figure BDA0003660919430000058
is the wavenumber, λ is the wavelength, and (x, y) is the coordinates of the array element.
Further, in the third step of the fast imaging method of the present invention, the scanning phase weighting is performed on the array signal according to the two mutually different scanning attribute parameter values, and the central view direction of the imaging system is adjusted by the scanning phase weighting, and the calculation formula is as follows:
Figure BDA0003660919430000059
wherein s is 2 For scanning the phase-weighted array signal,
Figure BDA0003660919430000061
for the scan phase weights in the x-direction of the array,
Figure BDA0003660919430000062
a scanning phase weighted value in the y direction of the array;
wherein the x-direction scan phase weighting value of the array
Figure BDA0003660919430000063
The calculation method of (2) is as follows:
Figure BDA0003660919430000064
scanning phase weighting values for y-direction of array
Figure BDA0003660919430000065
The calculation method of (2) is as follows:
Figure BDA0003660919430000066
wherein (theta) ζ ，θ ξ ) The sign sin represents a sine function for the angular coordinate corresponding to the central viewing direction of the imaging system.
Furthermore, in the fourth step of the fast imaging method of the present invention, amplitude weighting is performed on the array signal to reduce imaging noise floor, and the calculation formula is as follows:
s 3 ＝s 2 A；
wherein s is 3 The array signal after amplitude weighting is carried out, and A is an amplitude weighting coefficient;
methods of amplitude weighting include, but are not limited to, uniform distribution, cosine weighting, hamming window, Taylor distribution, chebyshev distribution, and hybrid weighting methods.
Furthermore, the fast imaging method of the invention adopts the efficient parallel algorithm in the fifth step to carry out fast imaging processing on the array signals, and the calculation formula is as follows:
Figure BDA0003660919430000067
wherein Q is t Spectral domain images, omega, obtained for fast imaging processing δ 、ω σ As spectral coordinates, symbols
Figure BDA0003660919430000068
Representing efficient parallel algorithm functions;
the efficient parallel algorithm includes, but is not limited to, two or three dimensional FFT, IFFT, non-uniform FFT, sparse FFT methods;
the spectrum coordinate omega corresponding to the fast imaging result δ 、ω σ The value range is as follows: omega δ ∈[0,2π]、ω σ ∈[0,2π]After fftshift operation, the value of ω is calculated δ 、ω σ The value range is transformed into: omega δ ∈[-π,π]、ω σ ∈[-π,π]The image at this time is an image conforming to the actual distribution:
Q(ω δ ,ω σ )＝fftshift[Q t (ω δ ,ω σ )]。
further, the performing coordinate inversion on the image field according to the two mutually different scan attribute parameter values in the sixth step of the rapid imaging method of the present invention includes:
carrying out coordinate calculation on an image field obtained by the efficient parallel algorithm, and carrying out coordinate inversion on the image field to obtain the distribution condition of a real target; wherein:
for the IFFT-type efficient parallel algorithm, the calculation formula of the angular coordinate of the image field scanning is as follows:
Figure BDA0003660919430000071
for the FFT-like efficient parallel algorithm, the calculation formula of the image field scanning angle coordinate is as follows:
Figure BDA0003660919430000072
wherein, theta δ 、θ σ Angular field scan coordinates, Δ, in the x-and y-directions, respectively x 、Δ y Cell spacing, symbol sin, in the x-and y-directions of the array cell, respectively -1 Representing an arcsine function;
the rectangular coordinate calculation formula of the image field is as follows:
Figure BDA0003660919430000073
wherein, δ and σ are rectangular coordinates of the image field in the x direction and the y direction respectively, the symbol tan represents a tangent function, and V is the distance from the imaging plane to the plane where the array is located;
the coordinate inversion calculation formula of the real target is as follows:
Figure BDA0003660919430000074
furthermore, the fast imaging method of the invention sets the array unit spacing
Figure BDA0003660919430000075
To avoid imaging aliasing;
and when the actual spacing of the array units does not meet the conditions, processing the data by adopting an interpolation method to ensure that the imaging non-aliasing condition is met.
In addition, the invention also provides a fast imaging method of the semi-holographic array, which is used for remote imaging and comprises the following steps:
the calculation formula suitable for the remote imaging is as follows:
Figure BDA0003660919430000081
and calculating an image field by adopting the efficient parallel algorithm, and obtaining the target distribution condition in a wide visual angle range through one-time operation.
In addition, the invention also relates to the application of the rapid imaging method in the fields of optical imaging, microwave imaging, radar detection, sonar, ultrasonic imaging, target detection based on sound, light, electricity and magnetism, imaging identification and wireless communication.
In conclusion, the method solves the imaging problem of the semi-holographic array with the mixed array attribute, has good application prospect, and can be widely applied to the field of target detection and wireless communication taking sound, light, electricity, magnetism and the like as media. When the detection medium is electromagnetic wave, the technology is suitable for microwave imaging, radar detection, wireless communication, synthetic aperture radar and inverse synthetic aperture radar; when the detection medium is sound wave and ultrasonic wave, the technology is suitable for sonar, ultrasonic imaging and synthetic aperture sonar; when the detection medium is light, the present techniques are applicable to optical imaging, synthetic aperture optical imaging, and the like.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the following drawings are only some embodiments described in the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without inventive labor.
Fig. 1 is a schematic diagram of an imaging system coordinate system of the rapid imaging method of the present invention.
Fig. 2 is a method flow diagram of the rapid imaging method of the present invention.
FIG. 3 is a diagram of the results of a semi-holographic imaging using the fast imaging method of the present invention, wherein: the left image is a target model, and the right image is a semi-holographic imaging result of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments and corresponding drawings. It is to be understood that the embodiments described are merely illustrative of some, but not all, of the present invention and that the invention may be embodied or carried out in various other specific forms, and that various modifications and changes in the details of the specification may be made without departing from the spirit of the invention.
Also, it should be understood that the scope of the invention is not limited to the particular embodiments described below; it is also to be understood that the terminology used in the examples is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention.
Example 1: a method for fast imaging of a semi-holographic array (see fig. 1-2), the method comprising the steps of:
the method comprises the following steps: determining two mutually different scanning attribute parameter values of the semi-holographic array;
in a semi-holographic array system, the scan attribute parameters η of the array in different directions x 、η y The values of (A) are different;
if the array unit in a certain direction of the array simultaneously transmits and receives the target signal, the scanning attribute parameter eta of the direction is selected x Or η y The value of (b) is 1;
if the array units in a certain direction of the array sequentially transmit and receive target signals, selecting a scanning attribute parameter eta of the direction x Or η y The value of (2).
Step two: and carrying out focusing phase weighting on the array signals according to the two mutually different scanning attribute parameter values, wherein the calculation formula is as follows:
Figure BDA0003660919430000091
wherein s is 1 For focusing the phase-weighted array signal, s 0 Is the array echo signal, e is the Euler constant, j is the imaginary unit,
Figure BDA0003660919430000092
for the focus phase weights in the x-direction of the array,
Figure BDA0003660919430000093
a focusing phase weighted value for the y direction of the array;
wherein the focusing phase weighted value of the x direction of the array
Figure BDA0003660919430000094
The calculation method of (2) is as follows:
Figure BDA0003660919430000095
focusing phase weighting for y-direction of array
Figure BDA0003660919430000101
The calculation method of (2) is as follows:
Figure BDA0003660919430000102
wherein R is the target slant distance, namely the distance from the target to the center of the array,
Figure BDA0003660919430000103
is the wavenumber, λ is the wavelength, and (x, y) is the coordinates of the array element.
Step three: scanning phase weighting is carried out on the array signals according to the two mutually different scanning attribute parameter values, the central view angle direction of the imaging system is adjusted through the scanning phase weighting, and the calculation formula is as follows:
Figure BDA0003660919430000104
wherein s is 2 For scanning the phase-weighted array signal,
Figure BDA0003660919430000105
for the scan phase weights in the x-direction of the array,
Figure BDA0003660919430000106
a scanning phase weighted value in the y direction of the array;
wherein the x-direction scan phase weighting value of the array
Figure BDA0003660919430000107
The calculation method of (2) is as follows:
Figure BDA0003660919430000108
scanning phase weighting values for y-direction of array
Figure BDA0003660919430000109
The calculation method of (2) is as follows:
Figure BDA00036609194300001010
wherein (theta) ζ ，θ ξ ) The sign sin represents a sine function for the angular coordinate corresponding to the central viewing direction of the imaging system.
Step four: and amplitude weighting the array signals to reduce imaging background noise, wherein the calculation formula is as follows:
s 3 ＝s 2 A；
wherein s is 3 The array signal after amplitude weighting is carried out, and A is an amplitude weighting coefficient;
methods of amplitude weighting include, but are not limited to, uniform distribution, cosine weighting, hamming window, Taylor distribution, chebyshev distribution, and hybrid weighting methods.
Step five: the method adopts an efficient parallel algorithm to carry out rapid imaging processing on array signals, and the calculation formula is as follows:
Figure BDA00036609194300001011
wherein Q is t Spectral domain images, omega, obtained for rapid imaging processing δ 、ω σ As spectral coordinates, symbols
Figure BDA00036609194300001012
Representing efficient parallel algorithm functions;
the efficient parallel algorithm includes, but is not limited to, two-dimensional or three-dimensional FFT, IFFT, non-uniform FFT, sparse FFT methods;
the spectrum coordinate omega corresponding to the fast imaging result δ 、ω σ The value range is as follows: omega δ ∈[0,2π]、ω σ ∈[0,2π]After fftshift operation, the value of ω is calculated δ 、ω σ The value range is transformed into: omega δ ∈[-π,π]、ω σ ∈[-π,π]The image at this time is an image conforming to the actual distribution:
Q(ω δ ,ω σ )＝fftshift[Q t (ω δ ,ω σ )]。
step six: performing coordinate inversion on the image field according to the two different scanning attribute parameter values, including performing coordinate calculation on the image field obtained by the efficient parallel algorithm, and performing coordinate inversion on the image field to obtain the distribution condition of the real target; wherein:
for the efficient parallel algorithm of the IFFT class, the calculation formula of the angular coordinate of the image field scanning is as follows:
Figure BDA0003660919430000111
for the FFT-like efficient parallel algorithm, the calculation formula of the image field scanning angle coordinate is as follows:
Figure BDA0003660919430000112
wherein, theta δ 、θ σ Angular field scan coordinates, Δ, in the x-and y-directions, respectively x 、Δ y Cell pitch, symbol sin, in x-and y-directions of the array cell, respectively -1 Representing an arcsine function;
the rectangular coordinate calculation formula of the image field is as follows:
Figure BDA0003660919430000113
wherein, δ and σ are respectively the rectangular coordinates of the image field in the x direction and the y direction, the symbol tan represents the tangent function, and V is the distance from the imaging plane to the plane where the array is located;
the coordinate inversion calculation formula of the real target is as follows:
Figure BDA0003660919430000114
in addition, in the method of the present inventionPitch of array cells
Figure BDA0003660919430000121
To avoid imaging aliasing;
and when the actual spacing of the array units does not meet the conditions, processing the data by adopting an interpolation method to ensure that the imaging non-aliasing condition is met.
Example 2: the method of the present invention (method of example 1) was used for the verification test of the imaging effect of the semi-holographic array
The test conditions are as follows: the targets are an ideal point target set in an F shape, and are located in the normal direction of the array, the distance between the point targets is 1m from the center of the array, and the distance between the point targets is 15 mm. The frequency of a detection signal is 10GHz, the distance between antenna units in the horizontal direction (x direction) is lambda/4, the distance between antenna units in the vertical direction (y direction) is lambda/2, the aperture of the array is 0.64m multiplied by 0.64m, a one-dimensional vertical linear array horizontal scanning imaging scene that the analog antenna units receive and transmit signals simultaneously is selected during imaging simulation, and eta is selected during imaging simulation x ＝2、η y See figure 3 for imaging results 1.
Example 3: a quick imaging method of a semi-holographic array is used for remote imaging, R is selected to be infinity, and a calculation formula suitable for the remote imaging is as follows:
Figure BDA0003660919430000122
(symbol)
Figure BDA0003660919430000123
and (3) representing an efficient parallel algorithm function, calculating an image field by adopting the efficient parallel algorithm in the embodiment 1, and obtaining the target distribution condition in a wide visual angle range through one-time operation.
The embodiments of the present invention are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The above description is only an example of the present invention, and is not intended to limit the present invention. Various modifications and changes may occur to those skilled in the art, and it is intended that the present invention cover such modifications, alterations, and substitutions as fall within the spirit and scope of the appended claims.

Claims (10)

1. A method for rapidly imaging a semi-holographic array, comprising the steps of:
the method comprises the following steps: determining two mutually different scanning attribute parameter values of the semi-holographic array;
step two: carrying out focusing phase weighting on the array signals according to the two mutually different scanning attribute parameter values;
step three: carrying out scanning phase weighting on the array signals according to the two mutually different scanning attribute parameter values;
step four: amplitude weighting the array signals;
step five: performing rapid imaging processing on the array signals by adopting an efficient parallel algorithm;
step six: and performing coordinate inversion on the image field according to the two different scanning attribute parameter values.
2. The fast imaging method according to claim 1, wherein said determining two mutually different values of scanning property parameters of the semi-holographic array in step one comprises:
in a semi-holographic array system, the scan attribute parameters η of the array in different directions x 、η y Are different in value;
if the array unit in a certain direction of the array simultaneously transmits and receives the target signal, the scanning attribute parameter eta of the direction is selected x Or η y Has a value of 1;
if the array units in a certain direction of the array sequentially transmit and receive target signals, selecting a scanning attribute parameter eta of the direction x Or η y The value of (2).
3. The fast imaging method according to claim 2, wherein the focusing phase weighting is performed on the array signals according to the two mutually different scan attribute parameter values in step two, and the calculation formula is:
Figure FDA0003660919420000011
wherein s is 1 For focusing the phase-weighted array signal, s 0 Is the array echo signal, e is the Euler constant, j is the imaginary unit,
Figure FDA0003660919420000012
for the focus phase weighting values in the x-direction of the array,
Figure FDA0003660919420000013
a focusing phase weighted value for the y direction of the array;
wherein the focusing phase weighted value of the x direction of the array
Figure FDA0003660919420000014
The calculation method of (2) is as follows:
Figure FDA0003660919420000021
focusing phase weights for y-direction of array
Figure FDA0003660919420000022
The calculation method of (2) is as follows:
Figure FDA0003660919420000023
wherein R is the target slant distance,
Figure FDA0003660919420000024
is wavenumber, λ is wavelength, and (x, y) is array elementAnd (4) coordinates.
4. The fast imaging method as claimed in claim 3, wherein the scanning phase weighting is performed on the array signals according to the two mutually different scanning attribute parameter values in step three by the following formula:
Figure FDA0003660919420000025
wherein s is 2 For scanning the phase-weighted array signal,
Figure FDA0003660919420000026
for the scan phase weights in the x-direction of the array,
Figure FDA0003660919420000027
a scanning phase weighted value in the y direction of the array;
wherein the x-direction scan phase weighting value of the array
Figure FDA0003660919420000028
The calculation method of (2) is as follows:
Figure FDA0003660919420000029
scanning phase weighting values for y-direction of array
Figure FDA00036609194200000210
The calculation method of (2) is as follows:
Figure FDA00036609194200000211
wherein (theta) ζ ，θ ξ ) The sign sin represents a sine function for the angular coordinate corresponding to the central viewing direction of the imaging system.
5. The fast imaging method of claim 4, wherein the amplitude weighting is performed on the array signals in step four, and is calculated by:
s 3 ＝s 2 A；
wherein s is 3 The array signal after amplitude weighting is carried out, and A is an amplitude weighting coefficient;
the amplitude weighting methods include uniform distribution, cosine weighting, hamming window, Taylor distribution, chebyshev distribution, and hybrid weighting methods.
6. The fast imaging method according to claim 5, wherein in step five, the fast imaging processing is performed on the array signals by using an efficient parallel algorithm, and the calculation formula is as follows:
Figure FDA0003660919420000031
wherein Q is a spectral domain image obtained by rapid imaging processing, omega δ 、ω σ As spectral coordinates, symbols
Figure FDA0003660919420000036
Representing efficient parallel algorithm functions;
the efficient parallel algorithm comprises FFT, IFFT, non-uniform FFT and sparse FFT methods.
7. The fast imaging method according to claim 6, wherein the coordinate inversion of the image field according to the two mutually different scan attribute parameter values in step six comprises:
carrying out coordinate calculation on an image field obtained by the efficient parallel algorithm, and carrying out coordinate inversion on the image field to obtain the distribution condition of a real target; wherein:
for the IFFT-type efficient parallel algorithm, the calculation formula of the angular coordinate of the image field scanning is as follows:
Figure FDA0003660919420000032
for the FFT-type efficient parallel algorithm, the calculation formula of the image field scanning angle coordinate is as follows:
Figure FDA0003660919420000033
wherein, theta δ 、θ σ Angular field scan coordinates, Δ, in the x-and y-directions, respectively x 、Δ y Cell pitch, symbol sin, in x-and y-directions of the array cell, respectively -1 Representing an arcsine function;
the rectangular coordinate calculation formula of the image field is as follows:
Figure FDA0003660919420000034
wherein δ and σ are rectangular coordinates of the image field in the x direction and the y direction respectively, the symbol tan represents a tangent function, and V is the distance from the imaging plane to the plane where the array is located.
8. The fast imaging method of claim 1, wherein the array element pitch is set
Figure FDA0003660919420000035
To avoid imaging aliasing;
and when the actual spacing of the array units does not meet the conditions, processing the data by adopting an interpolation method to ensure that the imaging non-aliasing condition is met.
9. A method of fast imaging of a semi-holographic array, for use in remote imaging, comprising:
the calculation formula suitable for the remote imaging is as follows:
Figure FDA0003660919420000041
the image field is calculated by adopting the efficient parallel algorithm according to claim 6, and the distribution condition of the targets in the wide visual angle range is obtained through one operation.
10. Use of the method of any one of claims 1-9 in the fields of optical imaging, microwave imaging, radar detection, sonar, ultrasound imaging, and acoustic, optical, electrical, magnetic based object detection, image recognition, wireless communications.
CN202210572821.7A 2022-05-25 2022-05-25 Rapid imaging method of semi-holographic array Pending CN114994667A (en)

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