118 results about "Phase gradient" patented technology

The invention discloses a phase residual error-based shallow defect detection method and device and a storage medium, which are used for improving the detection precision of shallow defects. Obtaining a reflection fringe pattern of the display screen to be detected; performing phase recovery on the reflection fringe pattern to generate first phase recovery data; calculating and generating a first phase gradient amplitude diagram according to the first phase recovery data; constructing a local average background gradient at each pixel according to the first phase gradient magnitude image; generating a first gradient residual image according to the first local average background gradient image and the first phase gradient magnitude image; performing visual contrast enhancement processing on the first gradient residual image; self-adaptive threshold judgment is carried out on the first anomaly enhancement graph, and a first structure defect mask graph is generated; performing feature fusion on the first phase gradient amplitude image, the first anomaly enhancement image and the first structure defect mask image; and inputting the first feature fusion image into a target shallow layer defect identification model for shallow layer defect detection, and generating a shallow layer defect detection result.

The invention provides an OTFS radar communication integrated signal processing method and system based on time-frequency-space domain joint optimization. According to the method, pilot symbol positions and densities are configured in an OTFS time-frequency grid according to channel time-varying characteristics and bandwidths, and a Doppler index range is set to optimize channel information acquisition; deploying a controllable reflecting surface, constructing a phase modulation matrix based on a target position and communication channel parameters, dynamically adjusting a phase gradient direction, and separating energy of a target echo and a communication signal; within a set Doppler index range, calculating frequency offset estimation, correcting a time domain sampling point of a received signal, and generating a phase correction vector; and positioning a spatial aliasing main interference area, and inhibiting symbol interference and spatial aliasing caused by a high-speed target through frequency domain beam forming weighting and phase rotation compensation in combination with a phase correction vector and a sub-Doppler parameter in the area. According to the invention, time-frequency-space domain cooperative efficient processing of OTFS radar communication integrated signals is realized.

The invention relates to the technical field of detection, in particular to a complex shell detection method and system based on structured light scanning. The method comprises the following steps: calculating a wrapped phase value and a phase modulation amplitude of each pixel point under each frequency, calculating discrete probability distribution containing candidate stripe series and a corresponding probability for each pixel point based on a multi-frequency wrapped phase difference, generating an initial pixel confidence map, and constructing an energy function; the penalty weight of the smooth item is determined according to the phase modulation amplitude and the wrapped phase gradient local variance, obtaining an initial fringe order distribution diagram, updating discrete probability distribution by using an initial pixel confidence map, re-minimizing an energy function to obtain a corrected fringe order distribution diagram, and reconstructing a final three-dimensional shape. And iteratively optimizing a projector principal point and a radial distortion coefficient in system calibration parameters. According to the scheme, the geometric details of the surface can be reserved, and the processing effect and the measurement precision of the complex curved surface and the high-curvature area are improved.

The invention relates to the technical field of geological disaster monitoring, and discloses a large-gradient deformation area phase optimization method and device, a medium and equipment, and the method comprises the steps: obtaining SAR data of a to-be-monitored area, and processing the SAR data to generate a differential interference image set; phase gradients of the differential interference image set in multiple directions are calculated to obtain a direction gradient image set, time sequence stacking and multi-direction fusion are carried out to obtain a phase gradient rate diagram, and a binary boundary diagram is determined through threshold segmentation; traversing the differential interferogram by using a sliding window, and performing structural consistency screening on neighborhood pixels in the window according to the binary boundary diagram to obtain a candidate pixel set; and performing amplitude consistency check, determining a homogeneous pixel set homogeneous with the central pixel, constructing a complex covariance matrix, and decomposing characteristic values to obtain an optimized phase of the central pixel. According to the method, the monitoring stability and precision are enhanced, the reliability and interpretability of a point selection result are improved, and an accurate phase reconstruction method is provided for a large-gradient deformation region.

The invention relates to a 5G communication antenna electromagnetic compatibility enhancement method, device and equipment, and belongs to the technical field of wireless communication networks, and the method comprises the steps: collecting frequency band-space electromagnetic intensity data in real time through a distributed sensor network, and constructing a three-dimensional mapping model in combination with base station beam parameters and polarization information; interference frequency band coordinates are screened based on the model, a phase gradient compensation value is calculated by using a polarization mismatch degree, an antenna array is driven to reconstruct a radiation pattern, and polarization orthogonal nulling is formed in an interference area; the port standing-wave ratio is synchronously monitored, closed-loop optimization is triggered, the antenna weight and the polarization direction are dynamically adjusted until indexes converge, and the problems of insufficient dynamic interference suppression precision, polarization mismatch compensation lag and the like in the prior art are solved.

The invention discloses a broadband wide-angle scanning array antenna based on a metasurface lens, belongs to the technical field of phased-array antennas, solves the problem of how to improve the scanning range and gain of the phased-array antennae, and is characterized in that the metasurface lens with phase gradient is loaded above the phased-array antenna on the basis of not changing the structure of the original phased-array antenna. The beam scanning range of the phased-array antenna is expanded, and the performance such as gain is improved; according to the invention, an original phased-array antenna does not need to be modified and redesigned, additional active devices do not need to be added, new components do not need to be introduced into an original system, the system cost is effectively reduced, the system size is reduced, and the antenna is suitable for scenes, such as unmanned aerial vehicles and low-altitude aircrafts, which have strict requirements on the size and the weight.

The invention relates to the technical field of defect detection, and discloses an insulating sleeve defect detection method and device based on electromagnetic induction, and the method comprises the steps: employing a main detection coil to excite a composite insulating sleeve to generate an electromagnetic field, and employing an auxiliary compensation coil to receive a mixed induction signal; performing interface reflection component extraction on the mixed induction signal, and calculating a dielectric parameter value of the composite insulating sleeve; calculating an interface compensation parameter of the auxiliary compensation coil based on the dielectric parameter value; generating a compensation magnetic field opposite to an interface reflection phase by using an auxiliary compensation coil according to an interface compensation parameter, and receiving a compensated detection signal by using a main detection coil and performing phase gradient analysis to obtain a position coordinate and a size parameter of an internal defect of the composite insulating sleeve; according to the invention, hardware-level separation of electromagnetic excitation and interface compensation is realized, active inhibition of interface reflection is carried out from a signal source, and automation and intelligentization of defect detection of the composite insulating sleeve are further realized.

The invention provides a composite material defect intelligent quantitative detection method based on multi-sensor phase signals, which comprises the following steps: calculating a phase gradient field according to continuous phase distribution, extracting a gradient peak region to indicate a wave reflection position, and fusing background interference correction to obtain defect boundary indication; if the phase gradient peak value exceeds a preset threshold value, gradient field features are analyzed through a convolutional neural network, defect phase change and background interference components are separated, and defect offset is judged; acquiring an offset mode through simulation comparison of the defect offset and the propagation path, classifying defect types corresponding to the offset mode by applying a support vector machine, and determining a type identification result; constructing a mapping function according to the type identification result and the offset, and associating phase change to geometric parameters, such as dimension depth orientation, to obtain a quantization parameter set; and verifying the matching degree with a phase gradient field through a quantization parameter set, and iteratively adjusting a mapping function to strengthen a stability relationship, so as to obtain a quantization model of defect parameters and phase changes.

The invention relates to a radio frequency coil design method for transmitting array space coding imaging, and belongs to the technical field of magnetic resonance imaging. Aiming at the problems of low single-dimensional coding efficiency, strong coupling interference among coils and nonlinear phase gradient in the traditional TRASE technology, axial and radial coding coils are designed based on a target field method and a magnetic dipole method, two-dimensional radio frequency phase coding is realized through reverse current solenoid decoupling combination, and excitation and signal receiving are realized in combination with a saddle-shaped coil. According to the technical scheme, by optimizing the coil structure and the decoupling design, multi-dimensional efficient coding, high-precision phase gradient, strong anti-interference and light system weight are achieved, and the method is suitable for portable and dynamic monitoring scenes of low-field magnetic resonance.

The invention discloses a phased array radar dimension reduction four-channel main lobe and side lobe interference resisting method, and relates to the technical field of signal processing, and the method comprises the steps: generating a virtual phase gradient field through dynamic topology regulation and control by employing the non-reciprocal electromagnetic characteristics of a magnetic monopole metamaterial, and executing the non-Abel quantum interference operation, multiple paths of virtual channel signals and quantum vacuum field component composite signals are generated; constructing interlayer entanglement parameters based on the multi-path virtual channel signals and the quantum vacuum field component composite signal, and reserving quantum superposition state characteristics with interference correlation through guidance of the interlayer entanglement parameters to generate a dimension reduction tensor; a curvature response geodesic projection operator is constructed in the hyperbolic Riemann space according to the dimensionality reduction tensor, main lobe strong interference and side lobe dispersion interference are separated through a local interference rejection field, and an interference component set is generated; according to the method, the inter-layer entanglement parameter is constructed and the dimension reduction tensor with the interference correlation maintaining capability is generated, so that synchronous identification and suppression of main lobe and side lobe interference are realized.

The invention relates to an on-chip dynamic control device for the wavefront of a terahertz metasurface transmission wave or surface wave, and belongs to the technical field of electromagnetic wave wavefront control devices. Since the traditional phase gradient metasurface fails to dynamically control the wavefront of a transmission wave or surface wave, the present invention combines an integrated photosensitive material metasurface with a spatially coded light source to realize on-chip dynamic control of the wavefront of a terahertz transmission wave or surface wave. The device deposits a dielectric layer on a metal reflective bottom plate, and the top layer of the dielectric layer is divided into two regions: an excitation region and an intrinsic region. The excitation region is composed of a metal ring array with multiple openings uniformly distributed and photosensitive materials deposited at the openings. By controlling the intensity of the pump light source irradiating the photosensitive material, a 2-bit coding unit is formed. The excitation region is constructed according to a preset coding sequence. When a circularly polarized wave is incident on the surface of the excitation region, a transmission wave or surface wave can be generated. By changing the coding sequence, the phase of the transmission wave or surface wave is reconstructed, and the wavefront of the transmission wave or surface wave is dynamically controlled, thereby realizing an on-chip dynamic control device for the wavefront of a transmission wave or surface wave.

The invention discloses a harmonic generation and beam control method and system based on an amplitude-phase regulation metasurface array. The method comprises the following steps of: constructing an amplitude-phase regulation and control metasurface array by adopting a digital control multi-channel radio frequency chip; based on a Fourier series and far field superposition model, calculating a time-varying amplitude phase sequence of harmonic waves and a phase gradient of beam pointing; the sequence is converted into a control signal through an FPGA, and each channel is modulated in real time; after an array receives a dot frequency signal, a target harmonic wave beam with a preset characteristic is radiated to a specified direction through periodic amplitude-phase modulation and space phase gradient processing. The system comprises an amplitude-phase regulation metasurface array construction module, a harmonic wave and beam control model construction module, a digital control signal generation loading module and a target harmonic wave generation radiation module, and is used for realizing the harmonic wave generation and beam control method. Accurate generation of any order of harmonic waves and flexible deflection of wave beams are achieved, the system integration degree, the regulation and control precision and the real-time performance are improved, and the application field is wide.

The invention relates to the technical field of medical instrument volume detection, and discloses a medical instrument internal volume detection system. A continuous wave and a pulse modulation signal are simultaneously transmitted through an annular phased array microwave antenna array, three-dimensional dielectric constant distribution is reconstructed by adopting a compressed sensing algorithm, and Doppler time-frequency domain characteristics are extracted through short-time Fourier transform; and inputting the phase gradient field and Doppler velocity field features into a convolutional neural network to generate a four-dimensional space-time volume evolution model, separating a macroscopic volume trend and a microcosmic pulsation component by adopting an adaptive Kalman filtering algorithm, and predicting an abnormal hemodynamic event through a long-short-term memory network. The technical problem of real-time precise detection of the multi-dimensional volume parameters of the blood circulation medical instrument under the complex pulsating flow condition is solved, and accurate evaluation of the instantaneous volume value, the pulsation amount and the pulsating frequency spectrum and early warning of abnormal events are achieved.

According to the electromagnetic stealth metasurface design method universal for any frequency band, the pattern area of the metasurface unit is divided into the grids, each grid can be pasted or not pasted, and therefore ever-changing paster patterns can be formed, the combinations are optimized through the particle swarm optimization, and the expected electromagnetic scattering characteristic is achieved. The design method comprises the two steps of metasurface unit optimization design, metasurface modeling and simulation verification. The metasurface unit optimization design is an automatic optimization design process following a particle swarm algorithm, m different metasurface units can be obtained, and the m different metasurface units present specific phase gradients on a center frequency and a neighborhood frequency band; the metasurface can be formed by selecting the metasurface units from the m different metasurface units. The invention aims to provide an electromagnetic stealth metasurface design method universal for any frequency band. According to the method, the metasurface unit combination meeting the requirement can be fully automatically generated only by giving the target frequency band and setting a small number of parameters according to the rule, and the requirement for human intervention is reduced to the maximum extent.

The invention discloses a PMD three-dimensional measurement method of a self-adaptive fringe projection mode. The method comprises the following steps: firstly, based on the surface topography characteristics of a measured mirror surface element, acquiring phase gradient distribution of the measured mirror surface element under a camera visual angle; secondly, according to the phase gradient distribution, self-adaptively modulating the local period of the projected fringes, so that the structured light fringes formed on the imaging surface of the camera after being reflected by the measured surface are integrally kept uniform and have moderate sparsity; projection is carried out by using the adaptive fringe pattern, a fringe image modulated by a measured surface is collected, and a corresponding relation between camera pixels and projection pixels is established; and finally, reconstructing the three-dimensional shape of the measured mirror surface element through ray tracing. According to the method, the local density of the stripes on the projection screen is adaptively adjusted according to the angle transformation characteristic of the reflected light of the measured surface, so that the measured structured light stripes in the visual angle of the camera are uniformly distributed and are properly sparse, and the PMD measurement precision is maximized under the condition that the morphology analysis integrity is ensured.

The invention discloses a self-adaptive phase gradient self-focusing imaging method suitable for a strip SAR (Synthetic Aperture Radar), and belongs to the technical field of synthetic aperture radar signal processing. In order to solve the problems that a traditional phase gradient self-focusing PGA algorithm is difficult to be directly applied to a strip SAR due to multi-point interference and phase error space-variant characteristics, and the processing flow of the traditional phase gradient self-focusing PGA algorithm is not matched with that of a conventional RD imaging algorithm and the like, the invention provides a novel imaging compensation method. The method comprises the following steps: firstly, sequentially carrying out range-direction and azimuth-direction dechirp processing on SAR echo data, and carrying out Fourier transform to obtain a preliminary complex image, thereby fundamentally solving the application premise problem of a PGA algorithm; then, detecting and positioning strong scattering points in the complex image, and carrying out self-adaptive partitioning on the image according to the spatial distribution characteristics of the strong scattering points so as to effectively isolate mutual interference among different targets; then, independently applying a PGA algorithm to each sub-block, and accurately estimating and compensating a phase error introduced by non-ideal motion of the platform through an iteration mode; and finally, synthesizing the compensated sub-blocks into an SAR image which is clearly focused. According to the method, the estimation precision of the phase error is remarkably improved, and high-quality self-focusing imaging of the strip SAR data can be realized.

The invention provides a broadband achromatic super lens based on a cross structure double-layer medium. The lens is composed of three layers of structures which are a dielectric layer, a cross-structure alpha-Si array layer and a cross-structure TiO2 array layer from bottom to top in sequence. The double-layer medium shows an approximately linear smooth phase gradient, completely covers a 2pi phase interval, and effectively reduces the aspect ratio to 4: 1. The phase modulation capability of the cross-structured double-layer dielectric arrays with different sizes is obtained through scanning, and the optimal matching of actual phase and theoretical phase contours is carried out, so that the super lens can realize an achromatic function in a target wave band. In addition, the antenna also has the advantages of polarization insensitivity, broadband operation, easy integration and the like. Therefore, a new device design thought is provided for a wide-spectrum imaging and virtual reality / augmented reality optical display system.

The invention relates to the technical field of electric energy distribution and signal energy distribution control, and discloses a product quality detection method based on machine vision, which comprises the following steps: acquiring signal energy distribution data representing product surface energy density, and mapping the signal energy distribution data to a complex frequency domain space to analyze a multi-scale phase component; constructing a local structure tensor by using a phase gradient, determining a background texture direction consistency index, establishing a phase feedback compensation mechanism, and adjusting a phase consistency weighting coefficient; according to the method, the problem of phase dispersion caused by non-uniform reflection is solved, the energy signal-to-noise ratio of the weak features is improved by dynamically adjusting the gain loop and energy distribution, and the signal-to-noise ratio of the weak features is improved. And precise quality identification under a high-reflection working condition 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 relates to a dual-polarization 2bit transmission type metasurface unit working in a Ka wave band, which can realize four-state phase regulation and control of horizontal polarization and vertical polarization on a specified frequency band. And an implementation scheme with a better system integration advantage is provided for the high-frequency multi-polarization reconfigurable antenna system. The unit is composed of two groups of linearly polarized 2bit reconfigurable units which are orthogonally arranged, and each unit is composed of a pair of active receiving antennas at the bottom and a pair of active transmitting antennas at the top; a pair of PIN diodes are respectively integrated in a receiving antenna and a transmitting antenna, and four discrete phase states are realized through combination of switch states, so that 2-bit phase regulation and control are completed. The invention has the following advantages: 1, low transmission amplitude loss and precise phase gradient characteristic are shown in the dual-polarization Ka wave band, and high-precision wave beam regulation and control can be realized; 2, due to the fact that dual-line polarization adopts a synchronous regulation and control mode, the unit can complete phase control only through two feeder lines, and compared with an independent polarization control scheme, the complexity of a feed and bias network is remarkably reduced, so that interference of a bias circuit on electromagnetic radiation characteristics is effectively reduced; and 3, the emergent wave beam of the transmission type metasurface is located on the same side with the transmission type metasurface, so that the shielding of the feed source can be reduced, the interference of a reflection path is avoided, the aperture efficiency is improved, and the sidelobe is reduced.

The invention belongs to the technical field of acoustic lenses, and discloses a high-frequency vortex sound field lens which comprises a stainless steel sheet substrate, the center area of the substrate is a solid area, and a periodic spiral line hollow structure is formed on the periphery of the solid area through laser processing; the area where the spiral line hollow structure is located allows sound waves to pass without shielding, and the solid area blocks sound wave propagation. The ultra-short pulse laser micromachining technology is adopted, the spiral line hollowed-out structure with the screw pitch, the line width and the spiral angle strictly matched with the high-frequency sound wave wavelength can be accurately etched in the surface of the stainless steel sheet, the spiral phase gradient is accurately constructed through the acoustic impedance difference of hollowed-out area conduction-solid area blocking, and the spiral phase gradient is accurately measured. The problem of phase error amplification under high frequency is effectively suppressed, the orbital angular momentum transfer efficiency is improved to 90% or above, and stable generation of a high-frequency vortex sound field is successfully realized.

This invention provides a method for correcting the localization errors caused by field inhomogeneity and obtaining position information of a wireless marker in an MRI scanner. In one embodiment, said method comprises the steps of: a) Providing said wireless marker in said workspace; b) Performing a pulse sequence with said MRI scanner, comprising: i) Exciting all spins inside said workspace; ii) Applying a pre-phasing gradient along a frequency encoding; iii) Applying dephasing gradients in two directions orthogonal to said frequency encoding direction; and iv) Applying two readout gradients with same amplitude and opposite polarities along said frequency encoding direction to form a first and a second gradient echo; c) Acquiring a first and a second MR signal using an array of RF receiver coils by sampling said first and second gradient echoes respectively; and d) Reconstructing tracking signals from said first and second MR signals and calculating said position information.

The invention discloses an under-sampling interference fringe wrapped phase demodulation method, and relates to the technical field of optical detection, the invention relates to an under-sampling interference fringe pattern wrapped phase demodulation method, according to an original to-be-demodulated wrapped phase, the phase gradient distribution of the original to-be-demodulated wrapped phase in x and y directions is calculated: gradx, grady; according to the method, the characteristic that phase data to be demodulated are continuous and derivable is utilized, and the method of mode Zernike polynomial fitting and residual least square fitting is combined to complete demodulation of the under-sampled fringe pattern wrapped phase data. According to the method, the problem that the dynamic range is limited in the interference measurement process can be solved without changing the hardware conditions of the interferometer, such as changing the wavelength of a light source or increasing the resolution of a detector, and particularly, the method has a good application effect on large deviation errors caused by the edge effect of the surface of an optical element in the initial stage of optical processing.

The invention provides an InSAR orbit phase fine modeling method combining a frequency domain and a space domain, and the method comprises the steps: 1, obtaining a synthetic aperture radar image data set of a target region, carrying out the preprocessing, and carrying out the pairwise interference, and obtaining an initial interferogram; 2, a flat ground winding phase and a terrain winding phase in the interferogram are reserved, and an orbit phase influenced by a baseline is obtained; thirdly, the azimuth fringe frequency and the distance fringe frequency of the interferogram are obtained through Fourier transform and linear frequency modulation transform, and the azimuth phase gradient and the distance phase gradient are calculated; fourthly, an orbit fine phase model is established according to the phase gradient and the space polynomial model; according to the method, the track accurate phase model combining the frequency domain and the space domain is established, linear and non-linear track phases caused by inaccurate base lines are removed at the same time under the condition that InSAR interference diagram unwrapping is not needed, and the precision of track phase error removal is improved.

The application relates to a radio frequency coil design method for transmit array spatial encoding imaging, and belongs to the technical field of magnetic resonance imaging. In view of the problems of low single-dimension coding efficiency, strong coupling interference between coils and nonlinear phase gradient of a traditional TRASE technology, axial and radial coding coils are designed based on a target field method and a magnetic dipole method, two-dimensional radio frequency phase coding is realized through reverse current solenoid decoupling combination, and excitation and signal receiving are realized in combination with a saddle coil. Through optimization of the coil structure and decoupling design, the technical scheme achieves multi-dimensional efficient coding, high-precision phase gradient, strong anti-interference and system light weight, and is suitable for the portability and dynamic monitoring scene of low-field magnetic resonance.

The invention relates to a terahertz video SAR (Synthetic Aperture Radar) fine imaging method, device and equipment and a medium. The method comprises the following steps of: approximating a distance difference into a linear function related to the speed of a platform, correcting range walk through a keystone method, considering the influence of the vertical distance from scattering points of different distance units to an air route on imaging quality in secondary phase error compensation, constructing a corresponding secondary phase error function, and meanwhile, calculating the imaging quality under the minimum entropy criterion. According to the method, secondary phase errors in radar signals are accurately compensated, after phase gradient self-focusing, the image is still affected by speckles, at the moment, an anisotropic extended filtering method is adopted, the influence of the speckles is restrained, and a fine terahertz video SAR image can be obtained through the method.

The invention discloses a preemption and perception cross spoofing attack detection method based on systematic residual check. The method comprises the following steps: acquiring a damaged signal subjected to a PSCS attack; performing discrete Fourier transform on the damaged signal to obtain a plurality of resource elements, and extracting a phase gradient and an amplitude deviation for each resource element; defining a non-attack state constraint function and an attack state constraint function by using the phase gradient and the amplitude deviation corresponding to each resource element, so as to express the construction of test statistics as a minimum and maximum optimization problem; a minimum and maximum optimization problem is converted into a semi-definite programming problem through a kernel tensor completion technology, and test statistics are obtained by solving the semi-definite programming problem; based on the test statistics, calculating a detection threshold according to a false alarm probability; and calculating the current test statistic of the to-be-detected signal in the current time slot, and if the current test statistic is greater than the detection threshold, judging that the PSCS attack exists, thereby realizing the effective seizing and sensing cross spoofing attack detection method.

The invention provides an optical imaging image spot two-dimensional position measurement precision limit optimization method, device and equipment, relates to the technical field of optical imaging precision measurement, and aims to realize optical imaging image spot two-dimensional position measurement precision limit analysis of a small-size PSF system. The method comprises the steps of performing approximation of phase gradient distribution of a PSF in a pixel space according to an energy concentration distribution characteristic of an imaging image spot of a small-size point spread function (PSF) optical system, and obtaining a gradient distribution approximation result of the PSF; according to the gradient distribution approximation result of the PSF, estimating the two-dimensional position measurement precision limit of the imaging image spot of the small-size PSF optical system on the image detector; and calculating an implementation condition that the two-dimensional position measurement precision limit meets the minimum value, and calculating analytic estimation of the two-dimensional position measurement optimal precision limit according to the implementation condition and the two-dimensional position measurement precision limit.

The invention discloses a spectrograph high-precision wavelength calibration method based on optical filter hardware interception, and the method comprises the steps: placing an optical filter in an interference light path, limiting the spectrum range in a hardware manner, and enabling a camera to directly collect an interference spectrum signal with a sharp boundary; extracting wave crest and wave trough positions of the interference spectrum signal, calculating a local half cycle and fitting to obtain a half cycle change curve; calculating a phase gradient to obtain a wavenumber gradient; solving a relative function of wave numbers through an integral accumulation mode; establishing a mapping relation between a pixel coordinate and a wavelength by combining cut-off wavelength information of the optical filter, and completing wavelength calibration of the spectrograph; performing interpolation resampling on the interference spectrum signal based on a calibration result; and Fourier transform is carried out on the re-sampled interference spectrum signal to obtain depth information. According to the invention, the problem that the existing calibration method depends on an expensive light source, and is insufficient in precision or high in complexity can be solved.

This disclosure provides a method for generating an image of an object using an MRI system, the method comprising providing a readout-coded imaging shearing (SIREN) gradient pulse in a phase gradient signal waveform. The phase gradient signal waveform is applied to the phase gradient coil of the MRI system. The application of the SIREN gradient pulse provides the object's SIREN k-space, which has SIREN k-space lines with shear angles. MR image spatial data from this SIREN k-space is then obtained by applying reconstruction techniques. Finally, the image of the object is generated by transforming the SIREN MR image spatial data into regular image spatial data based on the shear angle using a decoding algorithm.