49 results about "Near field imaging" patented technology

The invention provides a synthetic aperture radiometer error correction method and system, terminal equipment and a medium, and the method comprises the steps: obtaining an original brightness temperature image of a target near-field imaging scene, and obtaining a corresponding initial near-field visibility function; inputting the initial near-field visibility function into a pre-constructed near-field error compensation network model, extracting frequency domain feature information, and compensating a near-field error to obtain a new near-field visibility function; calculating an error between the new near field visibility function and the target far field visibility function, and if the error is less than or equal to a preset error threshold, performing Fourier transform inversion on the new near field visibility function to obtain a corrected reconstructed brightness temperature image; otherwise, constructing a loss function according to the error, carrying out the back propagation of the near-field error compensation network model, obtaining a trained near-field error compensation network model, and obtaining a corrected reconstructed brightness temperature image based on the trained near-field error compensation network model. The near-field error can be corrected, and the quality of the reconstructed brightness temperature image is improved.

The invention belongs to the technical field of near-field imaging, and particularly relates to a microwave and millimeter wave near-field subsurface microscopic imaging device and method based on signal interference, and the device comprises a vector network analyzer, a signal separation device, a phase adjustment device, a semi-steel coaxial line, a displacement platform, and an industrial control computer. The vector network analyzer comprises a signal separation unit, a frequency synthesis source, a first receiver and a second receiver, wherein the frequency synthesis source, the first receiver and the second receiver are respectively connected with the signal separation unit and used for generating microwave and millimeter wave test signals. The signal separation device is respectively connected with the vector network analyzer, the phase adjusting device and the semi-steel coaxial line, and the displacement table is connected with the vector network analyzer through the industrial personal computer; the tail end of the semi-steel coaxial line, which is far away from the signal separation device, is provided with a conical needle tip-shaped near-field probe; and the needle tip of the near-field probe is vertical to the surface of a to-be-detected sample arranged on the displacement table.

The invention relates to the technical field of millimeter wave near-field imaging, in particular to a near-field imaging method for a sparse MIMO array cylindrical scanning SAR system, and the method comprises the steps: dividing a complete comprehensive array of the SAR system into a plurality of sub-arrays, selecting local echo data corresponding to the plurality of sub-arrays from complete echo data, and calculating the local echo data of each first-stage sub-array in (u, v, v); according to the method, a uniform sampling grid with a uniform sampling rate in an (x, y, z) coordinate system is obtained, the uniform sampling grid is converted into a first-level non-uniform sampling grid in the (x, y, z) coordinate system, a first-level sub-image is reconstructed in the first-level non-uniform sampling grid based on local echo data, and a pairwise coherent superposition process is iteratively executed; and obtaining a three-dimensional imaging result of the target linear sparse MIMO array cylindrical scanning SAR system. According to the invention, the calculation complexity of imaging can be effectively reduced, and accurate and efficient near-field three-dimensional imaging of an arbitrary linear sparse MIMO array cylindrical scanning SAR system is realized.

To provide a method of near-field radar image reconstruction from radar data.SOLUTION: The method includes: receiving radar data corresponding to an image; and segmenting the image into multiple sub-images. Each sub-image includes a section of the image. The method further includes, for each sub-image, generating shifted data, by multiplying the radar data by a shifting term. The shifting term accounts for a distance between a center of the image and a center of the sub-image. The center of the sub-image is corrected for a curvature of a wavefront of a radar pulse. The method further includes: generating reduced data by filtering and downsampling the shifted data, such that a total amount of the shifted data is reduced; and reconstructing the sub-image, by back-projecting the reduced data. Performing the shifting by using the shifting term reduces distortion in the reconstructed sub-image.SELECTED DRAWING: Figure 2

The invention discloses a multi-mode nanometer measurement system and method based on terahertz scattering type scanning near-field optical microscopy and multi-frequency electrostatic force microscopy, and belongs to the technical field of near-field imaging, the measurement system comprises an AFM main body, a terahertz source, an optical path system, a terahertz detector, a multi-frequency signal generator and two phase-locked amplifiers; terahertz waves emitted by the terahertz source reach the terahertz detector through the optical path system, and near-field optical signals are obtained. The AFM comprises a metal coating probe; the multi-frequency signal generator generates sinusoidal signals with frequencies of omega1 and omega2; a sample is placed on the scanner, and the cantilever beam is controlled to vibrate at the frequency omega 1; an alternating voltage with the frequency of omega 2 is applied to a metal coating probe arranged at the top end of the cantilever beam; laser emitted by the laser is reflected to the light spot position detector through the cantilever beam, and morphology and electrostatic force signals are obtained through the two lock-in amplifiers respectively. According to the invention, a morphology signal, an optical signal and an electrostatic force signal can be synchronously obtained through single scanning.

The present invention discloses a tunable pump terahertz broadband near-field imaging and spectroscopy device and its usage method, which relates to the field of terahertz near-field microscopes. The device includes: a first fiber laser oscillator, a second fiber laser oscillator, an optical fiber beam splitter, a first delay line, a second delay line, a third delay line, a fourth delay line, a transmitting antenna, a first parabolic mirror, a second parabolic mirror, an atomic force microscope, a receiving antenna, a processor, a synchronous phase-locked loop, a first energy adjustment module, a second energy adjustment module, a first reflector and a second reflector; the present invention realizes the advantages of high pump light energy and tunable pump wavelength in a terahertz near-field microscope.

This invention relates to the field of RCS testing technology, specifically to an image-domain-based near-field anomalous scattering filtering method. The method first obtains a raw near-field image by near-field imaging of the acquired near-field swept data. Second, based on set anomalous scattering judgment conditions, the anomalous scattering centers are identified and extracted. Then, using a point target as a reference object, the scattering field distribution in the determined filtering area is simulated and reconstructed to generate a new near-field image. Finally, it is determined whether the new near-field image meets the anomalous scattering judgment conditions. If not, a filtered near-field image is generated. By identifying and removing scattering centers that do not belong to the test target from the two-dimensional image generated by the near-field imaging, near-field clutter suppression and higher-precision radar cross section testing are achieved.

The invention relates to the technical field of near-field imaging, in particular to a papillary thyroid carcinoma identification method based on terahertz imaging. According to the technical scheme, the method comprises the following steps that two sets of sections at the same position of the thyroid tissue of a patient are obtained, one set is stained sections, and the other set is unstained sections; and comparing the two groups of slices through an optical microscope, observing the position corresponding relation of the two groups of slices, and selecting an observation area based on cell morphological characteristics. According to the invention, synchronous acquisition of tissue apparent morphology and internal structure under nanoscale resolution is realized through the terahertz near-field imaging system, automatic analysis of an undyed thyroid section can be completed within 30 minutes by combining multi-modal feature fusion and a target detection algorithm, objective positioning and diagnosis scores of a cancerous region are directly output, and the accuracy and accuracy of diagnosis of the cancerous region are improved. And rapid, lossless and quantitative papillary thyroid carcinoma identification is realized.

Various embodiments described herein provide for multi-projector (i.e., two or more) imaging devices that utilize an integrated illuminator-sight optic. Embodiments of the present disclosure minimize misalignment of non-repairable components to improve overall accuracy associated with operation of the device. Additionally, the integrated illuminator-sight optic enables embodiments disclosed herein to be disposed in a significantly smaller form factor than conventional multi-projector imaging devices. An exemplary device includes: a near field imaging lens and a far field imaging lens; an integrated illuminator-sight optic positioned between the near field imaging lens and the far field imaging lens; a near field illuminator source and a far field illuminator source positioned for projection via the integrated illuminator-sight optic; a near field imaging sensor associated with the near field imaging lens; a far field imaging sensor associated with the far field imaging lens; and a device chassis for aligning the various components for operation.

An s-SNOM subsurface defect fine imaging method and system based on polarization laser scattering guidance belong to the technical field of optical nondestructive testing, and are realized based on a laser, a polarizer, a polarization modulator, a sample to be tested, an optical splitter array, an analyzer array and a detector which are sequentially arranged along the laser propagation direction, and the sample to be tested comprises subsurface defects. Firstly, a to-be-detected sample is subjected to polarization scattering rapid detection to obtain polarization scattering data; secondly, performing quantitative analysis and risk assessment on the non-uniformity of the subsurface structure to obtain a region of interest; thirdly, performing region-of-interest extraction and detection task scheduling on the high-risk region; and finally, performing high-resolution near-field scanning imaging on the region of interest. On the basis of keeping the advantage of s-SNOM high-resolution imaging, cross-scale cooperation between polarization scattering information and near-field imaging can be realized by introducing a rapid and effective prior guiding mechanism, and efficiency and precision are both considered in large-area sample detection.

The invention specifically relates to a rapid three-dimensional near-field imaging method based on a millimeter wave MIMO antenna array system, and the method comprises the steps: selecting a scene center as a reference point in a first stage, and carrying out the conversion from multiple stations to a single station; then, a coarse imaging result of the whole scene is generated by applying 3D-RMA; in the second stage, the imaging scene is divided into blocks, and fine imaging results of all target positions are obtained by applying a 2D-RMA slicing algorithm with fast calculation for several times. The invention aims to solve the problems that the storage burden of high-dimensional data is reduced, the imaging quality is ensured, the calculation complexity is greatly reduced, the approximate error of a reference point is eliminated, the problem of near-field defocusing caused by far-field hypothesis failure is solved, and the near-field three-dimensional real-time focusing imaging is realized.

The invention belongs to the technical field of near-field imaging, and particularly relates to a near-field imaging device and method based on a vector network analyzer. The vector network analyzer host is used for outputting a radio frequency local oscillator signal and a radio frequency test signal and receiving an intermediate frequency test signal; the millimeter wave terahertz spread spectrum module is used for frequency multiplication and signal separation of radio frequency test signals; frequency multiplication is carried out on the radio frequency local oscillation signal, and the frequency multiplication radio frequency local oscillation signal and a near-field signal are mixed and then output; an antenna, a quasi-light path and a near-field scanning control module; and the control machine is respectively connected with the vector network analyzer host and the near-field scanning control module. According to the millimeter wave terahertz near-field imaging device based on the vector network analyzer, generation and demodulation processing of millimeter wave terahertz test signals can be realized at the same time through the vector network analyzer host, and the size and the weight of a millimeter wave terahertz near-field imaging test system are reduced; and the integration level of the millimeter wave terahertz near-field imaging test system is improved.

This invention discloses a controller capable of switching terahertz wave circular dichroism (CD) and linear dichroism (LD). The controller comprises a dielectric layer embedded in a U-shaped silicon rod, a dielectric layer embedded in a metal open square ring, a dielectric layer, and a base layer. The interaction between the top composite structure and the dielectric layer generates strong circular dichroism (CD). The controller can also achieve switching between CD and LD by varying the conductivity of the photosensitive silicon pump light. The controller has a simple structure and can achieve dual-polarization dichroism. It has broad application prospects in fields such as polarization detection and near-field imaging.

The invention discloses a sparse near-field SAR (Synthetic Aperture Radar) imaging method based on multi-constraint index high-order total variation, which belongs to the technical field of radar imaging and comprises the following steps: S1, sampling a scene and preprocessing scene echo data; s2, calculating an NFCS approximate observation operator; s3, constructing a mixed sparse near-field SAR imaging model; s4, initializing parameters of the mixed sparse near-field SAR imaging model and an NFCS approximate observation operator; s5, updating the mixed sparse near-field SAR imaging model, and completing near-field SAR mixed constraint sparse imaging; and S6, performing imaging output. According to the method provided by the invention, target scattering intensity amplitude information can be accurately reconstructed, underestimation of L1 regularization on target scattering point intensity is avoided, speckle noise can be suppressed, artifacts can be avoided, difference between target sparsity and target scattering intensity is considered, and complex scene imaging performance is improved.

The invention discloses a thyroid cancer near-field imaging quality improvement method, belongs to the technical field of terahertz biological imaging, and mainly solves the problems of small test signals, imaging scratches and insufficient definition of thyroid cancer in a near-field imaging test. The method mainly comprises the following steps: S110, scanning a sample without adjustment to observe a near-field imaging effect; s120, carrying out stylus marking operation, and then carrying out secondary scanning; s130, adjusting an integral proportion and a differential gain parameter, and carrying out three times of scanning; and S140, changing the integral time in the lock-in amplifier, and carrying out near-field imaging scanning test on the thyroid cancer sample for four times. The method has the advantages that the near-field imaging quality of the thyroid cancer sample can be effectively improved, and the operation is simple and easy to operate.

The application provides a wave band splicing terahertz near field imaging system and method based on a frequency selective surface, which comprises a terahertz spread spectrum module, a first combination module, a parabolic mirror and a near field probe.The terahertz spread spectrum module is used for generating a terahertz signal and receiving a reflection signal of a near field terahertz signal of a sample to be measured.The first combination module is used for combining the terahertz signal generated by the terahertz spread spectrum module and converging to the parabolic mirror.The parabolic mirror is used for collecting the terahertz signal incident on the frequency selective surface and converging to the tip of the near field probe.The near field probe is used for modulating the terahertz signal by exciting the terahertz signal in the vertical direction to obtain the near field terahertz signal and reflecting the near field terahertz signal to the terahertz spread spectrum module.The reflection signal of the near field terahertz signal is the same as the light path of the incident terahertz signal.The application can realize terahertz near field imaging test in a wide band range by using the multi-wave band splicing terahertz near field imaging test technology based on the frequency selective surface.

The invention relates to a high-repetition-frequency strong-field terahertz coupled near-field imaging system, which belongs to the technical field of terahertz time-domain spectroscopy, solves the problems of low terahertz source power and low monopulse energy in a near-field probe scanning system in the prior art, and comprises a femtosecond laser light source (1) for providing femtosecond pumping laser; the non-polarized beam splitting sheet (3) divides the pump laser provided by the femtosecond laser light source (1) into two beams, the two beams are respectively provided for a light path of the pump laser and a light path of the probe light, and one beam of pump laser is converted into terahertz radiation through the light path of the pump laser; and the sample scanning module comprises a terahertz near-field probe (20) and is used for receiving terahertz radiation to carry out terahertz scanning and imaging on the surface of the sample.

The application relates to the technical field of fast near-field imaging, in particular to a quadrilateral MIMO array fast near-field imaging method based on a GPU, which comprises the following steps: a host end issues control instructions and parameters to a high-speed signal processing board carrying an FPGA, an FPGA drives a frequency synthesizer module to generate a local oscillation signal and distributes the local oscillation signal to a quadrilateral MIMO array; the FPGA controls T / R radio frequency front-end devices, sequentially completes scanning operation of multichannel transmission and reception in a time division multiplexing mode, an ADC samples and converts collected echo signals into digital signals, and then the digital signals are transmitted to a GPU; a parallel imaging architecture is constructed in the GPU, and the whole imaging task is decomposed into several independent sub-imaging tasks; after the current sub-imaging task is completed, the current sub-image is superimposed with the last sub-image, until all the sub-imaging tasks are completed, three-dimensional imaging results of the whole imaging area are obtained, and the three-dimensional imaging results are returned to the host end for display.

The application relates to the technical field of millimeter wave near-field imaging, in particular to a near-field imaging method of a sparse MIMO array cylindrical scanning SAR system, wherein the method comprises the following steps: dividing a complete comprehensive array of the SAR system into multiple sub-arrays, selecting local echo data corresponding to the multiple sub-arrays from complete echo data, calculating a uniform sampling grid with a unified sampling rate of each primary sub-array in a (u, v, n) coordinate system, and converting the uniform sampling grid into a primary non-uniform sampling grid in an (x, y, z) coordinate system, reconstructing a primary sub-image in the primary non-uniform sampling grid based on the local echo data, and iteratively performing a two-by-two coherent superposition process to obtain a three-dimensional imaging result of the target linear sparse MIMO array cylindrical scanning SAR system. The application can effectively reduce the calculation complexity of imaging, and realizes accurate and efficient near-field three-dimensional imaging of an arbitrary linear sparse MIMO array cylindrical scanning SAR system.

A probe useful for introducing therapeutic materials between the neural sheath and contained neurovascular tissue provides a near field imaging device permitting final positioning of the probe to be conducted with submillimeter accuracy and a vacuum channel allowing the probe to be attached to the neural sheath to withdraw it and provide a defect through which therapeutic agents can be introduced.

Apparatuses, systems, and methods for providing a one sensor near far solution to minimize field of view mismatch and aiming offsets are provided. For example, an indicia reader utilizing dual optics may include an engine comprising a near field imaging optic and a far field imaging optic that split an imaging sensor array and a aimer; wherein the near field imaging optic, the far field imaging optic, and the aimer are configured in a triangular arrangement to minimize the field of mismatch and aiming offsets. In some embodiments, the far field imaging optic may be configured to utilize a two or more prisms to provide a periscope configuration.

The invention provides a living body detection technical method and system based on multi-channel MIMO radar near-field three-dimensional Doppler imaging and a storage medium. The system collects multiple frames of echoes and performs near-field imaging, constructs a cross-frame time sequence for the same pixel position and performs time direction FFT to obtain a pixel-level Doppler spectrum; and determining a living body area and outputting an alarm by taking the zero frequency point amplitude of the Doppler spectrum and the joint relationship between the maximum value and the mean value in the frequency band after the zero frequency point is removed as a criterion. According to the scheme, the motility replaces the shape to serve as the main criterion, parallel processing is combined with the MIMO virtual aperture and the assembly line, high resolution, low false alarm and real-time alarm are achieved, and the method is suitable for scenes such as security check, post check and logistics.

The invention discloses a vehicle-mounted SAR (Synthetic Aperture Radar) real-time imaging method based on an improved distance Doppler algorithm, and relates to a close-range and large-squint-angle imaging algorithm in a vehicle-mounted scene. The method comprises the following steps: dividing a full aperture into sub-apertures; compensating a residual video phase term; doppler frequency shift items caused by fast time are eliminated; carrying out high-order Taylor expansion on the distance and azimuth coupling terms of the signal, constructing a distance migration filter based on the second term of Taylor expansion to carry out distance migration correction, and constructing a secondary distance compression filter based on the third term and higher-order terms of Taylor expansion to carry out secondary distance compression; azimuth compression processing is carried out after distance dimension focusing, and two-dimensional focusing is completed; and after all the sub-apertures are focused, splicing the sub-aperture images to obtain a full-aperture image. According to the invention, high-order Taylor expansion is carried out on the distance and azimuth coupling term, so that the coupling term is accurately compensated, and high-precision near-field imaging can be completed while the advantage of the classical RDA imaging speed is kept.

The invention relates to a distributed sparse MIMO array structure design method suitable for near-field imaging, and the method comprises the steps: obtaining an initial value of each particle and an initial structure of a sparse MIMO array based on the distribution characteristics of the sparse MIMO array and at least one to-be-optimized variable with the size determined, combining a Voronoi diagram method with effective weight distribution of a space-variant frequency spectrum to propose a novel optimization function, calculating the fitness of each particle, and determining the position and the global optimal fitness; calculating an initial temperature and a global optimal position of an annealing algorithm; and updating the speed and the fitness, carrying out annealing operation until an iteration termination condition is met, and generating an optimized single-module distributed sparse MIMO array. Therefore, the problems that in related technologies, an MIMO array design method has obvious grating lobes in near-field SAR imaging, and SAR image performance is reduced due to limitation of optimization of an objective function are solved.

The invention discloses a low-vibration near-field imaging system, and belongs to the technical field of near-field imaging, the system comprises a first support frame, a working spring, a second support frame and a shifter, the upper end of the second support frame is hung on the first support frame through the working spring, the second support frame is provided with a tray, and the tray is connected with a probe module for detecting a sample. The staggered design of the natural vibration frequency of the working spring and the vibration frequency of the cold table is combined with the composite vibration reduction structure of the double supporting frames, an efficient heat conduction path is constructed in cooperation with the heat conduction copper strip, and the vibration amplitude is reduced from the hundred nanometers to the micron level to the nanometer level; according to the imaging system, the reliability of the superconductive Josephson probe microscope during detection of a nano structure and surface waves is improved, the nano-scale high resolution of the superconductive Josephson probe is fully exerted, and the problem of vibration interference of a refrigerator in low-temperature microscopic imaging is successfully solved.

This invention relates to the field of millimeter-wave near-field imaging technology, and particularly to a handheld SAR three-dimensional fast near-field imaging method based on local spectral compression, comprising: acquiring raw echo data, dividing the complete synthetic array into 2 M‑1 1. Calculate a first-order subarray; for each first-order subarray, compute a uniform sampling grid with a uniform sampling rate in the (u,v,n) coordinate system, and convert it into a first-order non-uniform sampling grid in the (x,y,z) coordinate system; then, in the first-order non-uniform sampling grid, pair 2... M‑1 Reconstructing the first-order subarrays yields 2 M‑1 One first-level sub-image; for 2 M‑1 Each first-level sub-image is coherently superimposed pairwise to obtain at least two second-level sub-images. It is then determined whether these sub-images meet preset conditions. If not, the pairwise coherent superposition process is iteratively executed until the preset conditions are met, yielding the 3D reconstruction result. This solves the problems of low imaging quality and excessive computational complexity inherent in traditional imaging methods.

The application relates to a high-repetition-frequency strong-field terahertz coupling near-field imaging system, and belongs to the technical field of terahertz time-domain spectroscopy. The system solves the problem of low terahertz source power and single-pulse energy in a near-field probe scanning system in the prior art, and comprises a femtosecond laser light source (1) for providing femtosecond pump laser; a non-polarized beam splitter (3) for splitting the pump laser provided by the femtosecond laser light source (1) into two beams, which are respectively provided to the light path of the pump laser and the light path of detection light, and converting one of the pump lasers into terahertz radiation through the light path of the pump laser; and a sample scanning module comprising a terahertz near-field probe (20) for receiving the terahertz radiation to perform terahertz scanning and imaging on a sample surface.

A device comprising an image sensor for capturing a stream of asynchronous data representing per-pixel changes in radiance within a scene over an acquisition cycle and processing circuitry communicatively coupled to at least one light source positioned to illuminate at least an area of the scene, the processing circuitry configured to modulate output of the at least one light source over the acquisition cycle.

The invention relates to the technical field of millimeter wave imaging, in particular to a near-field imaging clutter suppression method and device based on comparative learning, and the method comprises the steps: collecting the complete echo data of a target body in a plurality of planes parallel to a radar array plane, so as to obtain the imaging results of the target body in the plurality of planes, determining a three-dimensional imaging result of the target body and layered imaging data of the target body at different distances; inputting a hierarchical maximum projection result of the hierarchical imaging data into a pre-trained near-field imaging clutter suppression network based on comparative learning to output a category-independent activation graph of the foreground; and respectively executing clutter suppression processing on each layer of the layered imaging data based on a mask matrix generated by the category-independent activation graph so as to suppress clutter data in the layered imaging data and reserve effective target data. According to the invention, foreground signals and complex background clutters can be effectively distinguished, accurate separation of the foreground and the background is realized, and the expressive force and practicability of imaging are enhanced.

This invention discloses a sparse near-field SAR imaging method based on high-order total variation with multiple constraint exponents, belonging to the field of radar imaging technology. The method includes the following steps: S1, sampling the scene and preprocessing the scene echo data; S2, calculating the NFCS approximate observation operator; S3, constructing a hybrid sparse near-field SAR imaging model; S4, initializing the parameters of the hybrid sparse near-field SAR imaging model and the NFCS approximate observation operator; S5, updating the hybrid sparse near-field SAR imaging model to complete hybrid constraint sparse near-field SAR imaging; and S6, outputting the imaging results. The method proposed in this invention can accurately reconstruct the target scattering intensity amplitude information, avoiding the underestimation of target scattering point intensity by L1 regularization, while also suppressing speckle noise and avoiding artifacts. It takes into account both the sparsity of the target and the differences in target scattering intensity, improving the imaging performance of complex scenes.