314 results about "Self-focusing" patented technology

The invention discloses a space-variant self-focusing imaging method for a missile-borne synthetic aperture radar sea surface moving target. The method comprises the following steps: acquiring a radar fundamental frequency echo signal; performing range pulse pressure and range migration correction on the radar fundamental frequency echo signal to obtain a correction signal, and further obtaining a coarse focusing radar image; extracting a single defocusing target image in the coarse focusing radar image, and inverting the single defocusing target image to an echo data domain to obtain data of single target energy; performing correction to obtain data after correction of the residual range walk; selecting a part of distance units from the data after the residual range walk is corrected, performing Doppler frequency modulation rate estimation on the selected part of distance units by adopting fractional Fourier transform, fitting the estimated Doppler frequency modulation rate by adopting a space-variant phase error model, and constructing a space-variant phase error compensation function of the target; and compensating the data after the correction of the residual range walk, and imaging. According to the invention, the refocusing effect of the moving ship target can be improved.

The invention discloses an SAR image fine focusing method based on fractional Fourier transform. Relates to the field of radar remote sensing technology application, in particular to the technical field of SAR image focusing processing. The technical problem that a motion compensation method based on inertial navigation data and a self-focusing method based on phase errors, which are commonly used in SAR image motion compensation methods, cannot meet the requirements of fine and rapid focusing is solved. The method comprises the following steps: S1, carrying out distance direction partitioning on a defocused SAR image to obtain a plurality of distance blocks; s2, calculating fractional Fourier transform of a strong point target in each distance block; s3, calculating a kurtosis characteristic of a fractional order Fourier transform result; s4, the maximum value of the kurtosis features is searched in a one-dimensional mode, and the optimal rotation order of each distance block is obtained; and S5, performing fractional Fourier transform on the SAR image based on the optimal rotation order of each distance block to obtain a focused SAR image.

The invention discloses a subaperture self-focusing CSAR imaging method combined with topographic relief error compensation, which comprises the following steps of: reading digital elevation model data of an observation scene, supplementing height direction information for grid points of an imaging area, and eliminating height direction errors; an echo signal acquired by the CSAR is converted into a frequency domain, multiplied by a reference signal and converted into a time domain signal, and range pulse compression is completed; segmenting the full-circumference aperture into a plurality of non-overlapped sub-apertures, and imaging the sub-aperture data by using a backward projection algorithm to obtain a sub-aperture image; a self-focusing algorithm based on an image sharpest criterion is adopted to process each sub-aperture image to carry out motion error compensation, phase errors are estimated, and iteration estimation is carried out for multiple times; and performing accumulation processing on the sub-aperture images after the self-focusing processing to obtain a high-precision full-aperture CSAR image. Compared with the prior art, the precision and quality of CSAR imaging can be improved by combining topographic relief error compensation and sub-aperture self-focusing processing.

The invention provides a self-focusing type wafer three-dimensional shape precision detection device and method. The self-focusing type wafer three-dimensional shape precision detection device comprises a super-radiation light-emitting diode, an optical fiber coupler, a microscopic reference arm provided with a reference arm microscope objective, a self-focal length wafer scanning platform of a microscopic scanning platform, a near-infrared reflection type spectrograph and an upper computer. During detection, near-infrared broadband light radiated by the diode is coupled into the optical fiber coupler and then is divided into detection light and reference light; moving the wafer to be detected to the focal point of the detection light; the detection light is focused on a to-be-detected wafer sample to form measurement light carrying sample surface information, then the measurement light is backscattered by the sample surface and interferes with the reference light at the optical fiber coupler, a formed interference light signal is captured by the near-infrared reflection type spectrometer and then is transmitted into the upper computer, the wafer sample is moved at the focus of the detection light, and the measurement light is transmitted to the lower computer. Performing X-axis and Y-axis scanning to obtain three-dimensional shape data of the wafer; according to the invention, the high-precision nondestructive detection of the three-dimensional shape of the chip can be realized under the condition that the chip sample is not damaged.

The invention discloses a light path system based on a gas-filled hollow-core optical fiber, and the system comprises a spectrum broadening device which comprises a first gas extraction chamber, a gas inlet chamber and a second gas extraction chamber, the first gas extraction chamber and the second gas extraction chamber are located at the two ends of the gas inlet chamber respectively, and the first gas extraction chamber and the gas inlet chamber are separated through a first sealing part; the second air exhaust chamber and the air inlet chamber are separated through a second sealing piece; the spectrum broadening device is internally provided with a hollow-core optical fiber and is provided with at least one through hole penetrating through the pipe wall of the hollow-core optical fiber, the two ends of the hollow-core optical fiber penetrate through the first sealing piece and the second sealing piece respectively so that the two ends of the hollow-core optical fiber can be communicated with the first air suction chamber and the second air suction chamber respectively, and the through hole is located in the air inlet chamber. The two ends of the hollow-core optical fiber are subjected to air exhaust, so that the ionization rate and the self-focusing effect generated when the laser is output after the spectrum of the inflated hollow-core optical fiber is broadened can be remarkably reduced, the requirement for improving the power input of the laser is met, and a light path system can bear higher laser monopulse energy compression.

An apparatus and method for radiation measurement are used to determine clearance of a rotating gas turbine component. The apparatus includes a probe body on a stationary component outward of the rotating component and a pair of sensor assemblies coupled to the probe body. Each sensor assembly includes a plurality of prisms coupled to the probe body Each prism of the plurality of prisms has a distinct angular orientation to direct radiation from the focusing lens to the rotating component surface off-axis with respect to an axis of the respective radiation source of the pair of radiation sources and with less directional variation than radiation from the respective radiation source.

The invention relates to the field of electromagnetic calculation, in particular to a petal-shaped Bessel light-based distance measurement method in hypersonic plasma turbulence, which comprises the following steps of: simulating plasma sheath turbulence by establishing a multi-layer random phase screen, calculating diffraction transmission of petal-shaped Bessel light after the petal-shaped Bessel light passes through the turbulence, and capturing intensity distribution of reflected light beams; the rotation angle is determined based on the correlation with the ideal intensity distribution, and high-precision distance measurement is realized by using the linear relation between the rotation angle and the propagation distance. The petal-shaped Bessel light is formed by superposing two Bessel mode light beams with different orbital angular momentum orders, has a spatial structure strongly related to the propagation distance, and can keep higher stability and anti-interference capability in a turbulent environment. By combining the self-focusing and approximately non-diffraction characteristics of the Bessel beam, the target detection and distance measurement precision in hypersonic plasma turbulence is remarkably improved, and reliable technical support is provided for communication and target detection of hypersonic aircrafts.

The invention discloses an achromatic self-focusing spinning terahertz emitter and a preparation method, and particularly relates to the field of spinning terahertz emitting equipment, and the achromatic self-focusing spinning terahertz emitter comprises a glass substrate, a spinning terahertz thin film and a magnet pair, wherein the spin terahertz film is formed by alternately arranging a ferromagnetic material and two heavy metal non-magnetic materials with the same spin Hall angle and opposite directions on the ferromagnetic material. According to the achromatic self-focusing spin terahertz emitter, the spin terahertz Fresnel zone plate is constructed by specially arranging two heavy metal non-magnetic materials with the spin Hall angles equal in size and opposite in direction, so that generated spin terahertz waves of more than two frequency bands are converged to the same point, the terahertz generation efficiency is high, and the terahertz wave generation efficiency is high. And meanwhile, the integration level of the spinning terahertz emitter is improved.

The invention discloses a path and focal nucleus variable high-intensity self-focusing ultrasonic transducer, and relates to the technical field of ultrasonic treatment, the path and focal nucleus variable high-intensity self-focusing ultrasonic transducer comprises an upper seat device and a sliding device, the upper seat device comprises multiple sets of focusing units, and the multiple sets of focusing units define a paraboloid structure along the same axis; the sliding device is arranged along the central axis of the paraboloid structure and can reciprocate along the central axis, when the sliding device moves into the paraboloid structure, the focusing unit slides outwards along the paraboloid to be unfolded, and when the sliding device moves away from the paraboloid structure, the focusing unit slides inwards along the paraboloid to be folded; according to the invention, by adjusting the unfolding or folding of the focusing unit, the dynamic adjustment of the size and shape of the focal nucleus is realized to adapt to tumors with different sizes and shapes, and the problems that the focal nucleus of the traditional ultrasonic transducer cannot be adjusted and the treatment adaptability is poor are solved.

A telescopic varifocal self-rotating OCT (optical coherence tomography) scanning probe belongs to the technical field of industrial surface imaging and comprises a casing large sleeve, a casing small sleeve, a probe and a miniature hollow motor. The shell large sleeve is an outermost layer straight sleeve, and the transparent short sleeve is adhered to the tail end of the shell large sleeve. The small sleeve is arranged in the large sleeve of the shell, the probe is arranged in the small sleeve, and the small sleeve is adhered to the motor sleeve; the probe comprises an optical fiber, a capillary glass tube, a self-focusing lens and a plano-convex lens which are sequentially arranged along the optical fiber in the direction from light incidence to a to-be-detected sample, and the probe part is bonded through optical cement. The tail end of the right side of the micro hollow motor is bonded with the reflecting prism, and the tail end of the left side of the micro hollow motor leads out a wire. According to the invention, the rotation of the hollow shaft of the micro hollow motor is controlled to drive the reflecting prism adhered to the tail end of the hollow shaft to rotate, so that the light path is changed, the drop point of the focused light beam is adjusted, the rapid circumferential scanning of various hole cavities is realized, and the imaging quality, the measurement capability and the measurement efficiency are improved.

The invention discloses an atmospheric transmission vortex light topological charge detection method based on light intensity distribution. The method comprises the following steps: firstly, generating a vortex light beam with a self-focusing characteristic, simulating an atmospheric turbulence environment by adopting a multi-phase screen method, calculating a transmission process of the light beam under an atmospheric turbulence condition by adopting a step-by-step Fourier method, and obtaining a light intensity distribution image at a focusing point; self-adaptive cutting and normalization preprocessing based on the mass center are carried out on the light intensity distribution image; and constructing a ResNet18 deep learning model containing eight residual blocks, and training by using the constructed data set to realize automatic identification of the topological charge number.

The invention discloses a self-focusing three-dimensional annular photoelectric gas sensor probe and a sensor device, comprising a three-dimensional annular concave reflection ring, which is characterized in that a section of concave circular ring containing a central cross section is cut by taking the central cross section of a hollow sphere as a centrosymmetric plane reference, and the reflection ring is fixed on a base; the base is provided with two light beam inlet and outlet through holes, and the two light beam inlet and outlet through holes are respectively provided with a plane mirror forming a 45-degree angle with the central section; a laser and a detector are arranged below the two through holes respectively, and the optical axes of the laser and the detector are both perpendicular to the central section. According to the invention, a laser light source of a light cone-shaped light beam with a very small divergence angle is adopted, and the focusing characteristic of a three-dimensional annular concave mirror is utilized, so that the light beam which is reflected for multiple times is converged on light of a detector, and a self-focusing reflection system in which the light source and the detector are focuses mutually is formed. The difficulty of adjusting the light path is reduced; and the overall design reduces the complexity of the production process, improves the production yield and is beneficial to large-scale production.

The invention relates to a THz-SAR moving target high-resolution imaging method, device and equipment, and the method comprises the steps: constructing a target echo model, representing the model as a distance image sequence in a matrix form based on a compressed sensing theory, constructing a distance image sequence model, constructing an azimuth phase error matrix through employing a maximized image contrast criterion, and carrying out the high-resolution imaging of a THz-SAR moving target. Constructing a target function according to the target range profile matrix, the background range profile matrix and a to-be-solved moving target image, introducing an imaging model and an auxiliary variable to restrain the target function, and converting the to-be-optimized target function into a plurality of sub-problems for iterative solution by adopting an alternating direction multiplier method; and expanding the moving target into a moving target self-focusing imaging network based on robust principal component analysis, preprocessing a target echo signal obtained by actual measurement, and inputting the preprocessed target echo signal into the network to obtain an SAR high-resolution imaging result of the moving target. By adopting the method, high-precision SAR imaging can be carried out on the moving target under the condition of high error sensitivity.

The invention provides an SAR (Synthetic Aperture Radar) self-focusing method for multi-stage sub-aperture segmentation, and relates to the technical field of radar signal processing. The method comprises the following steps: preprocessing original SAR echo data to obtain a coarse focusing SAR image; secondly, for a coarse focusing SAR image, reducing the image resolution by dividing frequency domain sub-apertures, and reducing the sensitivity of the image to a motion error; then, a focusing algorithm based on a model or a phase gradient is adopted in each stage of sub-aperture, and the image quality of each stage of sub-aperture with a good focusing effect is obtained; and finally realizing global focusing of the SAR image through step-by-step sub-aperture focusing. Compared with direct division of a plurality of sub-apertures, the method greatly improves the focusing effect of the SAR image while improving the efficiency, and is effectively verified in simulation, actual airborne flight and satellite-borne data.

The invention belongs to the technical field of laser vibration measurement, and provides a self-focusing laser Doppler vibration measurement method and system capable of resisting self-vibration of an optical fiber, and the method comprises the steps: adding a compensation light path which is used for sensing and generating reference light which is equal to an interference signal in amplitude and is opposite to the interference signal in real time in a Doppler vibration measurement light path, and taking the minimum mean square error as a self-adaptive matching criterion; interference phases obtained by synchronous demodulation of the compensation light path and the main light path are subjected to adaptive matching and cancellation in amplitude and phase dimensions, residual errors of vibration of the vibration measurement system and other environmental interferences are suppressed below noise of the vibration measurement system, and the purpose of balancing and weakening optical fiber vibration interferences in an instrument is achieved. The influence of the vibration factor of the instrument is reduced, and the interference influence is accurately eliminated through amplitude and phase matching by a demodulation algorithm corresponding to a compensation light path; meanwhile, by dynamically observing and updating the return light intensity threshold, low-frequency disturbance is resisted, and accurate automatic focusing is achieved.

The invention discloses a method for generating a multi-focus circular beam based on an all-dielectric metasurface, and the method specifically comprises the following steps: 1, constructing the all-dielectric metasurface which is composed of a plurality of arranged super atoms; the super atom comprises a square SiO2 substrate, and a rectangular Si nanorod is arranged on the SiO2 substrate; and 2, irradiating the all-dielectric metasurface by using left-hand circularly polarized light as incident light, and modulating the incident light by using a geometric phase and a propagation phase, so that emergent light of the all-dielectric metasurface forms a right-hand circularly polarized multi-focus circular light beam. According to the invention, the circularly symmetrical light beams with a plurality of self-focusing focuses can be efficiently and flexibly generated, and the number and the focal depth of the focuses can be adjusted as required.

The invention belongs to the technical field of radar signal processing, discloses a plasma sheath multi-order dispersion effect error compensation method, system, equipment, medium and program product based on two-step self-focusing processing, and aims to solve the problem of plasma sheath multi-order dispersion effect error influence of radar in the hypersonic flight vehicle imaging detection process. Obtaining a strong scattering point target in the image through strong point target search, and constructing a dispersion effect error compensation image matrix; based on a maximum contrast self-focusing processing principle and an image focusing theory, iteratively processing and compensating second-order and third-order phase errors of a dispersion effect; outputting an image after the multi-order dispersion effect error compensation, and realizing the accurate compensation of the multi-order dispersion effect error of the target wrapped by the plasma sheath; systems, devices, media for implementing the method, program products including computer programs implementing the method; the method has the characteristics of high dispersion effect error compensation precision, high compensation efficiency, strong adaptability and simple compensation processing steps.

The invention provides a circularly symmetric Airy beam wavefront phase modulation method based on a multi-focal-length lens. The method comprises the following steps: determining beam parameters of a CAB; calculating the self-focusing focal length d of the CAB; shielding all other light rings except the nth light ring, and solving the diffraction integral of the single light ring so as to obtain a focal length dn; the modulation focal length fn is reasonably estimated according to the difference value between the self-focusing focal length d and the single halo focal length dn, and the modulation focal length fn of each stage of halo is finely adjusted based on the obtained modulation focal length fn of each stage of halo, so that the optimal modulation effect is realized. On the premise that CAB initial light intensity distribution is not changed, higher energy concentration and better focusing characteristics are achieved, and the focusing precision of light beams is improved.

The coaxial collimator comprises a ceramic sleeve and an optical fiber assembly inserted into the ceramic sleeve, a center insertion hole is formed in the center of the ceramic sleeve in the length direction of the ceramic sleeve in a penetrating mode, the optical fiber assembly is inserted into the center insertion hole, and the inner surface of the center insertion hole is of a smooth structure. According to the scheme, the collimator adopts the self-focusing optical fiber as the collimating lens and is matched with the ceramic ferrule, so that the extremely small size is realized, and the collimator can be applied to the interior of a miniature optical device, such as a miniature probe and the like. The optical-mechanical coaxiality of the collimator is realized through a mechanical precision mode, the structure is simple, a complicated calibration process is not needed, the production efficiency is improved, and the labor cost is reduced at the same time.

The invention belongs to the technical field of optical measurement, and discloses an implementation device and method of a single-photon spectrograph, and the device comprises a spectral wavelength scanning module which is used for collecting a wide-spectrum optical signal, carrying out the wave division processing, and calculating the photon counting change rate between adjacent wavelengths; wavelength stepping is dynamically adjusted according to the photon counting change rate, self-adaptive scanning of spectrum change is achieved, and a single-spectrum optical signal is output; the self-focusing detection module is used for converting the single-spectrum optical signal into a photon event through a preset array channel; in a preset time window, calculating the variance and the Shannon entropy of each photon event, and constructing a local uncertainty index; performing spectral domain self-focusing and resampling according to the local uncertainty index to obtain photon counting data; high-precision, high-stability and high-efficiency spectrum light signal detection and visual analysis are realized.

The invention discloses an SAR image self-focusing distortion correction method and device, and belongs to the technical field of synthetic aperture radars. The method comprises the following steps: carrying out distance blocking and orientation sub-aperture division on a defocused SAR image, selecting a sample, and carrying out orientation decompression to a phase historical domain; performing azimuth dechirp processing on the sub-aperture data in each distance sub-block, and estimating a phase error through a standard PGA algorithm; after splicing sub-aperture phase errors and removing an overall linear phase, performing phase compensation and azimuth compression to obtain a focused image; and for azimuth distortion caused by residual linear phase of the compensated image, extracting a phase error linear term coefficient through a sliding window, deducing an azimuth shift distance in combination with Fourier transform time shift characteristics, and finally performing shift correction by adopting sinc interpolation. According to the method, the image focusing quality is improved, and meanwhile, the ground feature continuity and the image resolution are kept.

The invention discloses a nonlinear cascade laser amplifier based on a single crystal optical fiber, which relates to the technical field of laser and comprises a seed source, a pre-chirp management module, a single crystal optical fiber cascade module and a pulse compression module which are arranged along an optical path, a pumping source is further arranged between the pre-chirp management module and the single crystal optical fiber cascade module, and the pumping source emits pumping light to a light path between the pre-chirp management module and the single crystal optical fiber cascade module; the single-crystal optical fiber cascade module comprises a plurality of cylindrical single-crystal optical fibers which are connected in series. The nonlinear phase shift and the self-focusing length in the amplification process are regulated and controlled through mixed cascade of different types of single crystal optical fibers, so that few-period pulse amplification generation with high average / peak power is realized.

This invention discloses a phase compensation method for ship targets using ISAR based on block phase gradient autofocus. The steps include: pulse compression; range cell migration correction; range-oriented block segmentation; block phase compensation; calculation of the offset between adjacent image blocks; and image block alignment and stitching. This invention performs range-oriented block segmentation of the target echo, overcoming the shortcomings of existing technologies that ignore the spatial variation of rotational phase error, leading to defocusing in ship imaging, thus improving the accuracy of phase compensation and achieving good image focusing effect. Because this invention uses a phase gradient autofocus algorithm to compensate for the phase error within each block, and then uses a cross-correlation method to align and stitch the images of each block region, it overcomes the shortcomings of parameter estimation methods, such as complexity, time consumption, and poor real-time performance, and has the advantages of simple implementation, high efficiency, and strong real-time performance.

The invention discloses a block self-focusing ISAR (inverse synthetic aperture radar) imaging method and system based on an FPGA (field programmable gate array), and the method comprises the steps: obtaining ISAR echo data, and sequentially carrying out the preprocessing and global self-focusing processing, thereby obtaining a global self-focusing correction matrix; dividing the global self-focusing correction matrix into a plurality of sub-matrix blocks in a sliding window partitioning manner; performing minimum entropy self-focusing processing on each sub-matrix block to generate an optimized sub-matrix block; performing fast Fourier transform on the optimized sub-matrix blocks in the azimuth direction to generate two-dimensional image data; determining an offset according to an overlapping region of the adjacent sub-matrix blocks, performing cyclic shift processing on the two-dimensional image data corresponding to the current optimized sub-matrix block in the azimuth direction based on the offset, and aligning the two-dimensional image data corresponding to the previous adjacent optimized sub-matrix block; and outputting the aligned corrected two-dimensional image data as an ISAR imaging result. According to the invention, the azimuth focusing performance is improved, and the overall imaging quality is obviously improved.

The invention relates to the technical field of ultrafast laser, in particular to an ultraviolet laser damage inhibition method and device for a fused quartz optical element, and the method comprises the steps: obtaining oxy-18 modified DKDP crystals with oxy-18 isotope abundance higher than natural abundance; preparing the oxy-18 modified DKDP crystal into a wave plate matched with a preset ultraviolet laser wavelength; in an ultraviolet laser light path of a laser inertial confinement fusion device, a wave plate is arranged between a linear polarization state output end of ultraviolet laser and a fused quartz optical element; and enabling ultraviolet laser to sequentially pass through the linear polarization state output end and the wave plate to form circularly polarized light, and irradiating the circularly polarized light to the fused quartz optical element. The invention aims to realize the small-scale self-focusing effect of actively inhibiting fused quartz and solve the technical problem that a traditional material cannot be used as a large-aperture wave plate due to over-high transverse stimulated Raman scattering.

The invention discloses an SAR (Synthetic Aperture Radar) image self-focusing method and system based on error coefficient optimization. The method comprises the following steps: training a feature extraction module by using a defocused SAR image sample to establish a mapping relation between a defocused SAR image and a polynomial error coefficient; for a to-be-processed defocused SAR image # imgabs0 #, the defocused SAR image # imgabs1 # passes through a trained feature extraction module to obtain a polynomial error coefficient, the polynomial of a phase error vector is converted into an error matrix # imgabs2 #, the defocused SAR image # imgabs3 # is subjected to azimuth fast Fourier transform # imgabs4 # and then multiplied by the error matrix # imgabs5 #, and the defocused SAR image # imgabs3 # is obtained. And performing inverse fast Fourier transform # imgabs6 # on a result obtained by multiplication in the azimuth direction to obtain a focused SAR image # imgabs7 #. The SAR self-focusing method is small in manual intervention, high in calculation efficiency and better in interpretability, and the quality and effect of SAR image self-focusing are improved.

A device and method for solving the problem of the collimation of an output beam of an LD / LED for illumination, the device comprising an LD / LED, which is configured to output ultraviolet light or blue light; a lens group, which comprises a total internal reflection spherical lens and a GRIN lens and is configured to collimate an output beam of the LD / LED; and a spot analyzer, which is configured to analyze spots of the beam output by the LD / LED by means of the lens group. The present invention further relates to the method for solving the problem of the collimation of an output beam of an LD / LED for illumination. By using the device and method for solving the problem of the collimation of an output beam of an LD / LED for illumination, a total internal reflection spherical lens and a GRIN lens are added into the device; and by means of adjusting the heights of and the working distance between the total internal reflection spherical lens and the GRIN lens, the collimation of an output beam of an LD / LED is realized. A beam is collimated and shaped by means of the device, thus reducing the output light loss of the LD / LED, and improving the lighting effect and thermal stability of an LD / LED illumination light source. The device has a compact structure, rapidly and easily collimates and shapes the beam, and has a good collimation effect.

The present invention relates to the technical field of three-phase flow detection, and provides a fluorescent fiber optic probe device for three-phase flow detection, comprising: a packaging shell; a sapphire probe disposed within the packaging shell; a connected small-diameter self-focusing lens and a large-diameter self-focusing lens located above the sapphire probe; an integrated fiber bundle structure divided into a transmitting fiber and a receiving fiber within a main cavity; a laser transmitting module connected to the transmitting fiber; a collimating lens located above the receiving fiber; a trapezoidal waveguide structure located above the collimating lens; a first optical focusing assembly and a second optical focusing assembly disposed side by side above the trapezoidal waveguide structure, with a reflective volume holographic grating disposed below the first optical focusing assembly; a first photoelectric conversion module and a second photoelectric conversion module; and a main control module. The device of the present invention can effectively avoid optical power attenuation caused by optical fiber splitting and filters, thereby ensuring optical signal transmission efficiency and detection accuracy.

The invention discloses a handheld high-resolution millimeter-wave synthetic aperture radar imaging method. The method comprises the following steps: mixing signals acquired by a handheld high-resolution millimeter-wave radar to obtain intermediate-frequency signals; performing fast Fourier transform processing and residual video phase removal on the intermediate frequency signal; calculating the frequency response corresponding to the distance between the phase center of the radar antenna and the pixel point through linear interpolation; obtaining a preliminary result according to backward projection imaging; calculating position error estimation according to a minimum entropy self-focusing algorithm; and track correction is carried out according to the position error estimation, and then backward projection imaging is carried out again. The minimum entropy self-focusing backward projection algorithm provided by the invention takes image entropy minimization as an optimization target, compensates the position error of the phase center of the radar antenna through a coordinate descent method, does not need to depend on an external sensor, and effectively improves the imaging definition, thereby achieving compact and efficient imaging. The invention discloses a light and independent handheld high-resolution millimeter wave synthetic aperture radar system.

The invention provides a circumferential synthetic aperture sonar imaging motion compensation method based on a corner reflector, and the method comprises the steps: S1, carrying out the projection imaging of echo data after matched filtering, and determining the height of the corner reflector through an image variance; s2, according to the height of the corner reflector, the focusing position of the corner reflector is determined through the preliminary imaging result; s3, the distance between the corner reflector and the sonar is calculated according to the echo data when echoes are received each time; and S4, correcting the position of the sonar according to the focusing position of the corner reflector determined in the step S2 and the distance determined in the step S3, and performing projection imaging according to a new sonar position and echo data. According to the method, the corner reflector is used as an imaging reference target, the image quality of circumferential synthetic aperture imaging is improved, and the method is of great significance in reducing the calculation time of a self-focusing algorithm, improving the target imaging quality and the like.