CN112986987A - Three-dimensional microwave imaging system based on optical information processing - Google Patents
Three-dimensional microwave imaging system based on optical information processing Download PDFInfo
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- 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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- G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
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Abstract
The invention provides a novel three-dimensional microwave imaging system based on optical information processing. The invention realizes the range gating by the time aperture formed by delay lines with different lengths in the receiving array, and realizes the sampling of the spatial frequency of a plane space target image with a specific distance by the space aperture formed by the distributed antenna array, and finally realizes the three-dimensional microwave imaging of the detection target. In the present invention: microwave signals radiated and scattered from a detection target enter a microwave receiving antenna and are up-converted into optical signals by a microwave photon receiver, the optical carrier microwave signals finally enter an optical fiber micro-lens array, interference fringes are finally formed on a near-infrared CCD detector and are detected, the detection signals enter a high-speed signal processing module to be processed by an image inversion algorithm, and images are finally output. The system realizes three-dimensional imaging in a non-scanning mode, greatly improves the detection efficiency, and can be applied to microwave three-dimensional imaging and microwave radiation source positioning of targets.
Description
Technical Field
The invention mainly relates to a three-dimensional microwave imaging system based on optical information processing, which respectively realizes distance gating through time apertures formed by delay lines with different lengths, realizes sampling of the spatial frequency of a space target image of a specific distance plane through a spatial aperture formed by a distributed antenna array, and finally obtains three-dimensional microwave imaging of a detection target by utilizing an inversion algorithm.
Background art: microwave three-dimensional imaging and microwave optical information processing
The microwave is electromagnetic wave with frequency of 300 MHz-300 GHz and corresponding wavelength of 1 m-1 mm. Compared with radio waves, microwaves have the characteristics of high frequency, wide frequency band, large information capacity, short wavelength, penetration of an ionized layer, good directivity and the like, are widely applied, and have great significance in the aspects of communication, radar, guidance, remote sensing technology, radio astronomy, clinical medicine and wave spectroscopy.
Microwave imaging refers to an imaging means using microwaves as information carriers, and the principle is to irradiate the object to be measured with microwaves of the object itself or use microwaves to irradiate the object to be measured, and then reconstruct the shape or the (complex) dielectric constant distribution of the object through the measurement value of the scattered field outside the object. The microwave imaging has the characteristics of safety, low cost, capability of imaging temperature theoretically and the like. Microwave imaging goes through a single-antenna mechanical scanning mode to the existing aperture synthesis mode, and the performance of an imaging system is greatly improved through continuous development and perfection, but the performance of the imaging system is still not enough to meet the development requirements of the modern society.
For microwave imaging systems, synthetic aperture technology is an effective method to achieve high spatial imaging resolution. The technology utilizes a plurality of small-aperture antennas with small volume and light weight to be arranged into a sparse aperture array according to the shapes and the sizes of carriers and the rules of minimum redundant spatial frequency coverage, optimal imaging quality and the like, and reconstructs an image of an observed target by combining complex cross-correlation operation and discrete Fourier transform operation of every two antenna signals.
The theory and method for reconstructing target images of the passive synthetic aperture imaging system researched internationally still adopt the traditional microwave synthetic aperture imaging theory and method. Target radiation received by the antenna is mixed with a local oscillator through a mixer to generate a difference frequency signal, the signal is subjected to pairwise complex cross-correlation operation in a correlator after passing through an amplifier, and then is subjected to discrete Fourier inverse transformation through a signal processor to reconstruct an image of the target and display the image on a display.
For applications such as modern remote sensing, military reconnaissance and anti-terrorism, the traditional imaging theory and method have several disadvantages: (1) the system is complex and costly. (2) Real-time imaging is difficult to achieve. (3) Is easy to be interfered by electromagnetic wave, and has heavy weight and large volume. Although the traditional down-conversion imaging method has realized high-resolution synthetic aperture imaging, the traditional down-conversion imaging method still has the technical bottlenecks of complex microwave signal processing system, high cost, high possibility of being subjected to electromagnetic interference, large data volume needing to be processed and the like, so that real-time imaging is difficult to realize, and the whole system has the defects of overlarge volume, overweight and the like.
With the explosion development of optical and microwave technologies such as semiconductor lasers, high-speed photoelectric modulators, detectors, integrated optics, fiber optics and microwave antennas, microwave monolithic integrated circuits and the like, a new cross-domain combining the advantages of microwave and optical subjects appears, and a new subject, namely microwave photonics, is formed. Researchers begin to turn their eyes to microwave photonics, and use photonics technology to overcome the shortcomings of the traditional technology has achieved primary results in the military field. Photonics methods generally have the advantages of light weight, small size, fast speed, high bandwidth, electromagnetic interference resistance, good real-time performance, and the like.
The optical information processing adopted in recent years to realize the real-time imaging of the millimeter wave array provides a new approach for us, namely a microwave synthetic aperture photon imaging system: the idea is to combine the passive and optical synthetic aperture to form a high resolution real-time imaging system, and the combining point of the synthetic aperture and the optical synthetic aperture is achieved by electro-optical modulation. Firstly, an intermediate frequency amplified signal (carrying amplitude and phase information from a target) output by a heterodyne receiver modulates a light wave transmitted in an optical fiber through an electro-optical modulator, namely, the amplitude and phase information with the target is carried to the light wave transmitted in the optical fiber through the electro-optical modulator; the optical fiber array is a scaled array of a passive synthetic aperture antenna array, because light transmitted by each optical fiber in the optical fiber array is both light (coherent light) from the same laser and carries the amplitude and phase of target information detected by each antenna. Therefore, according to the passive optical synthetic aperture imaging theory, a detector array (such as a CCD) arranged on the imaging focal plane of the optical system can obtain the image of the target in real time.
The photonics technology has the advantages of large bandwidth and anti-electromagnetic interference, the data rate of transmission and processing in the optical domain is far beyond that of the electronics technology, and the teams led by the teaching of Kelvin and the teaching of Pather in the united states have been dedicated to the research of the airborne/satellite-borne synthetic aperture up-conversion imaging method since 2002, and have obtained a great deal of research results. For the purpose of realizing passive millimeter wave real-time imaging, Phase Sensitive corporation of the united states, combined with the university of telawa, develops a large number of technologies for processing millimeter wave imaging by adopting photonics technology. Their research work dates back to 2004 for the earliest time, when professor DW Prather at the university of talawa has just developed a preliminary research study for passive millimeter wave photonics real-time imaging. Subsequently, under the joint funding of multiple departments such as DARPA, air force and naval, 35GHz photonics imaging systems and 94GHz photonics imaging systems have been completed to date. In particular, a 220-unit passive 77GHz photonics real-time imaging system has been realized in recent years, and a real-time millimeter wave radiation image with 35 frames/second and good imaging quality is obtained. Meanwhile, the whole imaging system up-converts the millimeter wave radiation signal to an optical band at the beginning of an antenna receiving section, adopts optical fiber to transmit the signal and adopts a method of space light real-time direct interference imaging, thereby greatly reducing the volume, weight and power consumption of the passive millimeter wave imaging system. At present, the project group develops the development work of millimeter wave radiation real-time imaging systems with higher frequencies such as 95GHz under the subsequent subsidization of DARPA.
On the basis of the work, the invention realizes the distance gating by the time aperture formed by the delay lines with different lengths in the receiving array, and realizes the sampling of the space frequency of the space target image of the specific distance plane by the space aperture formed by the distributed antenna array, and finally realizes the three-dimensional microwave imaging of the detection target. The system realizes three-dimensional imaging in a non-scanning mode, greatly improves the detection efficiency, and can be applied to microwave three-dimensional imaging and microwave radiation source positioning of targets.
Disclosure of Invention
The invention provides a novel three-dimensional microwave imaging system based on optical information processing. The invention realizes the range gating by the time aperture formed by delay lines with different lengths in the receiving array, and realizes the sampling of the spatial frequency of a plane space target image with a specific distance by the space aperture formed by the distributed antenna array, and finally realizes the three-dimensional microwave imaging of the detection target. In the present invention: microwave signals radiated and scattered from a detection target enter a microwave array antenna, are up-converted to an optical frequency band by a microwave photon receiver to form optical carrier microwave signals, the optical carrier microwave signals pass through optical fiber transmission and real-time phase error correction control, enter a micro lens array after passing through optical fiber delay lines with different lengths to be collimated and expanded, finally form interference fringes on a near-infrared CCD detector, and finally enter a signal processing module to be processed by an image inversion algorithm and finally output an image. The system realizes three-dimensional imaging in a non-scanning mode, greatly improves the detection efficiency, and can be applied to microwave three-dimensional imaging and microwave radiation source positioning of targets.
The invention is mainly based on an optical information processing method, respectively samples the frequency domain and the space-frequency domain of a microwave signal radiated by a detection target through a sparse time aperture array and a sparse space aperture array, and then obtains three-dimensional microwave imaging through an inversion algorithm, and specifically adopts the following technical scheme:
the invention provides a novel three-dimensional microwave imaging system based on optical information processing, which is shown in figure 1 and is characterized in that: the three-dimensional microwave imaging system based on optical information processing comprises a receiving antenna array subsystem, a microwave optical fiber transmission subsystem, an optical fiber delay line array subsystem, an optical fiber array phase error control subsystem, an optical fiber array spatial interference and detection subsystem and a system control and data processing subsystem; the subsystems work in a coordinated manner: the receiving antenna array subsystem is responsible for receiving microwave signals scattered or radiated from the detected target; the microwave optical fiber transmission subsystem up-converts the microwave signals received by the receiving antenna array subsystem to optical frequency to form optical carrier microwave signals and transmits the optical carrier microwave signals in optical fibers; the optical fiber array phase error control subsystem realizes real-time phase error calculation and compensation of the optical carrier microwave signals transmitted in the microwave optical fiber transmission subsystem; the optical fiber delay line array subsystem delays the optical carrier microwave signals of each channel transmitted in the microwave optical fiber transmission subsystem by different optical fiber lengths; the fiber array space interference detection subsystem processes the delayed light-carried microwave signal output by the fiber delay line array subsystem to obtain interference fringes of the delayed light-carried microwave signal in space on an infrared CCD (charge coupled device) camera; the system control and data processing subsystem processes the interference fringes obtained by the infrared CCD camera through a data acquisition and image inversion algorithm, and finally realizes the three-dimensional microwave imaging of the detection target.
In the present invention, the various parts of the system are described as follows:
1. the receiving antenna array subsystem is a microwave array antenna consisting of N microwave antennas and is responsible for receiving microwave signals scattered or radiated from a detected target; the frequency range of the microwave array antenna can be selected from the range of 1-300 GHz according to application requirements; the bandwidth range of the microwave array antenna is also set according to the specific application requirements.
2. The microwave optical fiber transmission subsystem consists of a laser, an optical fiber beam splitter and N microwave photon receivers; light beams output by the laser are averagely divided into N +1 optical fiber channels through the optical fiber beam splitter for transmission; wherein, 1 optical fiber channel is used as a reference optical channel, and the rest N optical fiber channels directly enter the microwave photon receiver; the microwave photon receiver forms an optical carrier microwave signal after microwave signals output by the receiving antenna array subsystem are subjected to microwave amplification filtering and electro-optical modulation; the optical carrier microwave signal is transmitted in an optical fiber.
3. The optical fiber delay line array subsystem consists of N paths of optical fiber delay lines with different lengths, and different phase delays are realized for the same frequency components in the optical carrier microwave signals in different channels; meanwhile, in the same optical fiber delay line channel, different frequency components in the optical carrier microwave signal can generate different phase delays after passing through the same optical fiber delay line; the specific length of the N-path delay line is comprehensively designed and optimized according to the wavelength of light waves in the optical fiber and the frequency and bandwidth of received microwave signals scattered or radiated by the detected target.
4. The optical fiber array space interference detection subsystem consists of a micro-lens collimation and beam expansion array, a beam splitter prism, a narrow linewidth optical filter, a Fourier lens and a near infrared CCD detector; the micro-lens collimation beam expanding array collimates and expands the delayed light-carried microwave signals output by the optical fiber delay line array subsystem, when the delayed light-carried microwave signals pass through the beam splitter prism, part of light wave energy is reflected and then serves as input signals of the optical fiber array phase error control subsystem, and the rest of light wave energy is transmitted by the beam splitter prism and then enters the narrow-linewidth light filter to output single-side-band light-carried microwave signals; and finally, the single-side band optical carrier microwave signals of each channel are coherent on the surface of the near-infrared CCD detector after passing through the Fourier lens to form interference fringes, and the interference fringes are converted into electric signals by the near-infrared CCD detector and output.
5. The optical fiber array phase error control subsystem consists of an optical fiber collimation and beam expansion module, an optical filter, a focusing lens, an array detector, a phase correction processor, a phase modulation driving module and an optical fiber phase modulator; reference beams in 1 reference light channel output by the microwave optical fiber transmission subsystem are collimated and expanded by the optical fiber collimating and expanding module, and interfere with part of light-carried microwave signals reflected by a light splitting prism in the optical fiber array spatial interference detection subsystem on a focal plane of the focusing lens after passing through the optical filter, an interference result is converted into an electric signal by the array detector and is output to the phase correction processor, the phase correction processor calculates the size of a phase error needing to be corrected in real time by using a phase correction algorithm, converts the electric signal into the electric signal and inputs the electric signal to the phase modulation driving module, and finally drives each optical fiber phase modulator, so that real-time phase correction control is realized.
6. The system control and data processing subsystem consists of an image data acquisition card, a system state control module and a high-speed signal processing module; the image data acquisition card converts the electric signal output by the near-infrared CCD detector into a digital image signal, inputs the digital image signal into the high-speed signal processing module, and finally obtains a three-dimensional microwave imaging result of a detected target after the processing of an image inversion processing algorithm; the system state control module monitors the working state of the optical fiber array phase error control subsystem in real time, controls the data acquisition card to acquire data according to the frame rate of the near-infrared CCD detector, controls the high-speed signal processing module to receive digital image data output by the image data acquisition card, and controls the high-speed signal processing module to finally output three-dimensional microwave imaging data.
7. In the microwave optical fiber transmission subsystem, a microwave photon receiver consists of a multi-stage microwave low-noise amplifier, a filter and a high-speed electro-optic phase modulator; the multistage microwave low-noise amplifier amplifies the received microwave signals, and the amplified microwave signals enter a filter to filter signals outside the working bandwidth range of the system; the high-speed electro-optic phase modulator converts the amplified and filtered microwave signal into light wave frequency to finally obtain the optical carrier microwave signal.
8. In the optical fiber array spatial interference detection subsystem, the micro-lens collimation and beam expansion array is a scaling array of a receiving antenna array, and the positions of all units are in one-to-one correspondence; the beam splitting prism can enable the light beams entering the beam splitting prism to achieve partial reflection and partial transmission according to a specific ratio; the passband range of the narrow linewidth optical filter is located in one of two first-stage sidebands of the optical carrier microwave signal, and the output of the narrow linewidth optical filter is a single-sideband optical carrier microwave signal.
9. In the optical fiber array phase error control subsystem, the optical filter plate enables light waves with the same wavelength as the reference light beam to pass through in partial light wave signals reflected by the beam splitter prism, and the rest parts of the light waves cannot pass through; on the focal plane of the focusing lens, the light beams of a single channel only interfere with the reference light beam, and the light beams of different channels are not superposed in space and do not interfere with each other; the correction algorithm comprises a random gradient descent algorithm, a genetic algorithm, a heterodyne method, a hill climbing method and a perturbation method.
10. In the system control and data processing subsystem, the digital image signal is an interference fringe image signal on the surface of the near-infrared CCD detector; the image inversion processing algorithm adopts an image inversion processing algorithm based on deep learning.
The invention has the main characteristics that: the invention realizes three-dimensional imaging in a non-scanning mode, realizes distance gating through time apertures formed by delay lines with different lengths respectively, realizes sampling of spatial frequency of a space target image of a specific distance plane through a space aperture formed by a distributed antenna array, and finally obtains three-dimensional microwave imaging reconstruction of a detected target by using an inversion algorithm based on deep learning.
The invention has the benefits and application prospects that: the method can be applied to 3D microwave remote sensing and measurement and radiation source positioning, and the purpose of microwave three-dimensional imaging is realized.
Drawings
FIG. 1 is a three-dimensional microwave imaging system based on optical information processing according to the present invention
FIG. 2 is a diagram of a microwave photon receiver
FIG. 3 is a beam propagation pattern of a beam splitter prism
FIG. 4 is a schematic diagram of interference between a reference beam and an optical carrier microwave signal
FIG. 5 is a schematic diagram of the spectral distribution of an optical carrier microwave signal
Detailed Description
As shown in fig. 1, a three-dimensional microwave imaging system based on optical information processing.
The embodiment of the invention adopts a spiral antenna array consisting of 11 antennas on a single arm and 55 antennas on 5 spiral arms, and in the arrangement, the specific position of each antenna is obtained by optimization according to the principle of optimal spatial frequency coverage. In the embodiment, considering the transmission characteristics of the radiation signal in the atmosphere and the current shelf product condition of the microwave device, the radiation signal is taken as 40GHz as the center frequency of the antenna, and the bandwidth of the antenna is taken as 20GHz, and the receiving antenna array subsystem in the embodiment of the invention is established as follows: the microwave array antenna 1 employs a 30GHz to 50GHz receiving antenna ARH-2220-02 of WiseWave technologies inc.
The microwave photon receiver 2 is composed as shown in fig. 2, wherein a pre-low noise amplifier (LAN) adopts ALN-33144020-01 of WiseWave technologies inc, a following filter is specially designed to have a passband range of 30-50 GHz, a difference loss less than 2dB, and an out-of-band rejection above 30 dB. In order to realize the modulation of the signal with the center frequency of 40GHz, the electro-optical modulator 4 in the embodiment adopts ｃA Mach-40066-40-P-A-A electro-optical phase modulator of COVEGA Corporation, the maximum modulator of the electro-optical phase modulator reaches 40Gb/s, and the working bandwidth of the electro-optical phase modulator reaches 20 GHz.
Referring to FIG. 1, the beam entering the microwave photon receiver 2 is generated by a Koheras Adjustik E15 ultra narrow linewidth DFB semiconductor laser 3 with 3dB linewidth less than 1KHz and a center wavelength of 1536.61 nm. The output of the laser 3 is polarization maintaining light, which enters a standard polarization maintaining fiber beam splitter of 1 × 64 via a polarization maintaining fiber, and the light beam output by the laser is uniformly split into 64 beams by the fiber beam splitter 4 for output. And selecting 1 beam as reference light, entering a fiber collimation beam expander in a customized design, and selecting the other 55 beams to respectively enter a high-speed electro-optical modulator in the microwave photon receiver 2. The broadband microwave signal amplified by the LNA and filtered directly enters a radio frequency incident port of the electro-optical modulator to respectively perform phase modulation on light beams incident to the high-speed electro-optical modulator.
The light beam output after modulation by each electro-optical modulator is an optical carrier microwave signal, and the spectrum distribution diagram 5 of the signal is shown. The optical carrier microwave signals respectively pass through the corresponding optical fiber delay lines 5, the length of the corresponding optical fiber delay lines of each channel is an equal difference array with the difference of 5mm, light beams output by the optical fiber delay lines pass through an optical fiber phase modulator 6 for phase error correction, the light beams are output to form an optical fiber array at the tail end of the optical fiber, and the distribution position of the array on a space plane is an equal ratio reduction array distributed by the microwave array antenna. The topological structure of the array is the same as that of the antenna array, the scaling factor of the array needs to consider the frequency of light waves and modulation signals, the diameter ratio of collimated light beams to the aperture ratio of the antenna, the optimal value of the array scaling factor is 1, the original antenna array and the optical fiber array have the same spatial resolution at the moment, and the ratio of an image obtained on the second near-infrared CCD camera 19 behind the original antenna array to an image obtained by direct imaging of a real aperture is 1: 1.
the light beam output by the optical fiber array has a certain divergence angle, and is collimated by the SUSS FC-Q-250 type micro lens collimation and beam expansion array 7 corresponding to MicroOpitcis to obtain plane wave output. Before focusing on the focal plane of the fourier lens 11, the imaging beam is split into two beams using a splitting prism 9, as shown in fig. 3: one for phase error correction control applications; and the other beam is used for imaging, and after passing through a narrow-linewidth optical filter 10 and a Fourier lens 11 for focusing imaging, the beams interfere in space and are finally focused to a focal plane.
A near-infrared CCD detector 12 is placed at the focal position of the lens, an image data acquisition card 16 converts an electric signal output by the near-infrared CCD detector into a digital image signal, the digital image signal is input into a high-speed signal processing module 19, and a three-dimensional microwave imaging result of a detected target is finally obtained after the digital image signal is processed by an image inversion processing algorithm; the system state control module 20 monitors the working state of the phase correction processor 17 in the fiber array phase error control subsystem in real time, controls the data acquisition card to acquire data according to the frame rate of the near-infrared CCD detector, controls the high-speed signal processing module to receive digital image data output by the image data acquisition card, and controls the high-speed signal processing module to finally output three-dimensional microwave imaging data.
The working principle of the fiber array phase error control subsystem is shown in fig. 4, and the process is as follows: reference beams in 1 reference light channel output by the optical fiber beam splitter 4 are collimated and expanded by the optical fiber collimating and expanding module 8, are filtered by the optical filter 13 with part of optical carrier microwave signals reflected by the beam splitter prism 9, and interfere on the focal plane of the focusing lens 14, an interference result is converted into an electric signal by the array detector 15 and is output to the phase correction processor 17, the phase correction processor 17 calculates the size of a phase error needing to be corrected in real time by using a carrier interference phase correction algorithm, converts the electric signal into the electric signal and inputs the electric signal into the phase modulation driving module 18, and finally drives each optical fiber phase modulator 6, so that real-time phase correction control is realized.
Claims (11)
1. A novel three-dimensional microwave imaging system based on optical information processing is characterized in that: the three-dimensional microwave imaging system based on optical information processing comprises a receiving antenna array subsystem, a microwave optical fiber transmission subsystem, an optical fiber delay line array subsystem, an optical fiber array phase error control subsystem, an optical fiber array spatial interference and detection subsystem and a system control and data processing subsystem; the subsystems work in a coordinated manner: the receiving antenna array subsystem is responsible for receiving microwave signals scattered or radiated from the detected target; the microwave optical fiber transmission subsystem up-converts the microwave signals received by the receiving antenna array subsystem to optical frequency to form optical carrier microwave signals and transmits the optical carrier microwave signals in optical fibers; the optical fiber array phase error control subsystem realizes real-time phase error calculation and compensation of the optical carrier microwave signals transmitted in the microwave optical fiber transmission subsystem; the optical fiber delay line array subsystem delays the optical carrier microwave signals of each channel transmitted in the microwave optical fiber transmission subsystem by different optical fiber lengths; the fiber array space interference detection subsystem processes the delayed light-carried microwave signal output by the fiber delay line array subsystem to obtain interference fringes of the delayed light-carried microwave signal in space on an infrared CCD (charge coupled device) camera; the system control and data processing subsystem processes the interference fringes obtained by the infrared CCD camera through a data acquisition and image inversion algorithm, and finally realizes the three-dimensional microwave imaging of the detection target.
2. The three-dimensional microwave imaging system based on optical information processing according to claim 1, wherein the receiving antenna array subsystem is a microwave array antenna composed of N microwave antennas and is responsible for receiving scattered or radiated microwave signals from the detected target; the frequency range of the microwave array antenna can be selected from the range of 1-300 GHz according to application requirements; the bandwidth range of the microwave array antenna is also set according to the specific application requirements.
3. The three-dimensional microwave imaging system based on optical information processing according to claim 1, wherein the microwave optical fiber transmission subsystem is composed of a laser, a fiber beam splitter and N microwave photon receivers; light beams output by the laser are averagely divided into N +1 optical fiber channels through the optical fiber beam splitter for transmission; wherein, 1 optical fiber channel is used as a reference optical channel, and the rest N optical fiber channels directly enter the microwave photon receiver; the microwave photon receiver forms an optical carrier microwave signal after microwave signals output by the receiving antenna array subsystem are subjected to microwave amplification filtering and electro-optical modulation; the optical carrier microwave signal is transmitted in an optical fiber.
4. The three-dimensional microwave imaging system based on optical information processing according to claim 1 or 3, wherein the fiber delay line array subsystem is composed of N fiber delay lines with different lengths, and different phase delays are realized for the same frequency components in the optical microwave signals in different channels; meanwhile, in the same optical fiber delay line channel, different frequency components in the optical carrier microwave signal can generate different phase delays after passing through the same optical fiber delay line; the specific length of the N-path delay line is comprehensively designed and optimized according to the wavelength of light waves in the optical fiber and the frequency and bandwidth of received microwave signals scattered or radiated by the detected target.
5. The three-dimensional microwave imaging system based on optical information processing according to claim 1 or 4, wherein the optical fiber array spatial interference detection subsystem is composed of a micro-lens collimation and beam expansion array, a beam splitter prism, a narrow linewidth optical filter, a Fourier lens and a near infrared CCD detector; the micro-lens collimation beam expanding array collimates and expands the delayed light-carried microwave signals output by the optical fiber delay line array subsystem, when the delayed light-carried microwave signals pass through the beam splitter prism, part of light wave energy is reflected and then serves as input signals of the optical fiber array phase error control subsystem, and the rest of light wave energy is transmitted by the beam splitter prism and then enters the narrow-linewidth light filter to output single-side-band light-carried microwave signals; and finally, the single-side band optical carrier microwave signals of each channel are coherent on the surface of the near-infrared CCD detector after passing through the Fourier lens to form interference fringes, and the interference fringes are converted into electric signals by the near-infrared CCD detector and output.
6. The optical information processing-based three-dimensional microwave imaging system of claim 1, 3 or 5, wherein the optical fiber array phase error control subsystem is composed of an optical fiber collimation beam expanding module, an optical filter, a focusing lens, an array detector, a phase correction processor, a phase modulation driving module and an optical fiber phase modulator; reference beams in 1 reference light channel output by the microwave optical fiber transmission subsystem are collimated and expanded by the optical fiber collimating and expanding module, and interfere with part of light-carried microwave signals reflected by a light splitting prism in the optical fiber array spatial interference detection subsystem on a focal plane of the focusing lens after passing through the optical filter, an interference result is converted into an electric signal by the array detector and is output to the phase correction processor, the phase correction processor calculates the size of a phase error needing to be corrected in real time by using a phase correction algorithm, converts the electric signal into the electric signal and inputs the electric signal to the phase modulation driving module, and finally drives each optical fiber phase modulator, so that real-time phase correction control is realized.
7. The optical information processing-based three-dimensional microwave imaging system according to claim 1 or 5, wherein the system control and data processing subsystem is composed of an image data acquisition card, a system state control module and a high-speed signal processing module; the image data acquisition card converts the electric signal output by the near-infrared CCD detector into a digital image signal, inputs the digital image signal into the high-speed signal processing module, and finally obtains a three-dimensional microwave imaging result of a detected target after the processing of an image inversion processing algorithm; the system state control module monitors the working state of the optical fiber array phase error control subsystem in real time, controls the data acquisition card to acquire data according to the frame rate of the near-infrared CCD detector, controls the high-speed signal processing module to receive digital image data output by the image data acquisition card, and controls the high-speed signal processing module to finally output three-dimensional microwave imaging data.
8. The optical information processing-based three-dimensional microwave imaging system of claim 3, wherein in the microwave fiber transmission subsystem, the microwave photon receiver is composed of a multi-stage microwave low-noise amplifier, a filter and a high-speed electro-optical phase modulator; the multistage microwave low-noise amplifier amplifies the received microwave signals, and the amplified microwave signals enter a filter to filter signals outside the working bandwidth range of the system; the high-speed electro-optic phase modulator converts the amplified and filtered microwave signal into light wave frequency to finally obtain the optical carrier microwave signal.
9. The optical information processing-based three-dimensional microwave imaging system according to claim 1, 2 or 5, wherein in the optical fiber array spatial interference detection subsystem, the microlens collimation and beam expansion array is a scaled array of a receiving antenna array, and each unit position corresponds to one unit; the beam splitting prism can enable the light beams entering the beam splitting prism to achieve partial reflection and partial transmission according to a specific ratio; the passband range of the narrow linewidth optical filter is located in one of two first-stage sidebands of the optical carrier microwave signal, and the output of the narrow linewidth optical filter is a single-sideband optical carrier microwave signal.
10. The optical information processing-based three-dimensional microwave imaging system of claim 6, wherein in the optical fiber array phase error control subsystem, the optical filter is configured to allow a part of the optical wave signals reflected by the beam splitter prism to pass light waves having the same wavelength as the reference beam, while the rest of the optical wave signals cannot pass the reference beam; on the focal plane of the focusing lens, the light beams of a single channel only interfere with the reference light beam, and the light beams of different channels are not superposed in space and do not interfere with each other; the correction algorithm comprises a random gradient descent algorithm, a genetic algorithm, a heterodyne method, a hill climbing method and a perturbation method.
11. The optical information processing-based three-dimensional microwave imaging system of claim 7, wherein in the system control and data processing subsystem, the digital image signal is an interference fringe image signal of the surface of a near-infrared CCD detector; the image inversion processing algorithm adopts an image inversion processing algorithm based on deep learning.
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| CN115144856A (en) * | 2022-09-05 | 2022-10-04 | 中国人民解放军国防科技大学 | Method and device for inverting space target parabolic antenna parameters of polarized radar |
| CN117092133A (en) * | 2023-10-16 | 2023-11-21 | 成都市汇智讯新能源科技有限公司 | Detection system and detection method based on energy storage plate |
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| CN115144856A (en) * | 2022-09-05 | 2022-10-04 | 中国人民解放军国防科技大学 | Method and device for inverting space target parabolic antenna parameters of polarized radar |
| CN117092133A (en) * | 2023-10-16 | 2023-11-21 | 成都市汇智讯新能源科技有限公司 | Detection system and detection method based on energy storage plate |
| CN117092133B (en) * | 2023-10-16 | 2024-01-09 | 成都市汇智讯新能源科技有限公司 | Detection system and detection method based on energy storage plate |
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