304 results about "Interferometric phase" patented technology

A multi-channel imaging system is calibrated by measuring the geometric distortion in each sub-image, generating corresponding correction factors, and applying such factors to correct subsequent image data. In addition, intensity transfer-function arrays are measured at each pixel, and further used to correct for system and detector nonlinearities and nonuniformity between images. The procedure is repeated over a range of wavelengths to produce a complete set of correction coefficients and transfer functions. When the system is used for interferometric phase measurements, multiple measurements are preferably taken and a random phase offset in the reference path length is introduced at each measurement. The multiple phase data so derived are then averaged to reduce phase-dependent systematic measurement errors.

Structure profiles from optical interferometric data can be identified by obtaining a plurality of broadband interferometric optical profiles of a structure as a function of structure depth in an axial direction. Each of the plurality of interferometric optical profiles include a reference signal propagated through a reference path and a sample signal reflected from a sample reflector in the axial direction. An axial position corresponding to at least a portion of the structure is selected. Phase variations of the plurality of interferometric optical profiles are determined at the selected axial position. A physical displacement of the structure is identified based on the phase variations at the selected axial position.

The invention relates to a device for measuring a frequency scanning absolute distance based on a femtosecond optical frequency comb and a method for measuring the absolute distance based on the device. The device comprises: a tunable laser (1), a polarization maintaining fiber system (2), a double-frequency heterodyne interferometer (3) and a system for measuring a laser frequency and an interferometric phase (4); the tunable laser (1) is used for generating single-frequency, single-line polarization laser, and an output laser frequency can be controlled by the working voltage and current ofthe tunable laser; the polarization maintaining fiber system (2) is used for coupling space laser with a polarization maintaining fiber in an unreflected way, and dividing the space laser into three paths of optical signals with equal optical intensity, and keeping an output laser polarization direction the same as an input laser polarization direction; the double-frequency heterodyne interferometer (3) is used for converting single-frequency laser into double-frequency orthogonal polarization laser, and converting distance information to be measured into phase information of a laser beat signal; and the system for measuring the laser frequency and the interferometric phase (4) is used for precisely measuring and locking and inputting the frequency of the laser, and measuring a phase different between the two paths of alternating current signals.

The invention discloses a multi-source monitoring technology fusion-based ground subsidence integrated monitoring method. The method comprises laying benchmarks and GPS monitoring points in a ground subsidence focal monitoring area, laying a CR-GPS-benchmark integrated point in a ground stable region, in the same time sequence, acquiring GPS data, ground meteorological data, MODIS data, SAR images and leveling data, calculating GPS data through the combination of synchronous observation data from surrounding CGPS stations and IGS stations and ground meteorological data, calculating atmospheric delay phase information through the combination of GPS data, ground meteorological data and MODIS data, extracting stable PS point and PS point deformation information in an initial differential interferometric phase map, building a ground subsidence vertical deformation field through deformation formation corresponding to the PS points, GPS points, benchmarks and integrated points, constructing a spatial data field through fusion of a horizontal deformation field and a vertical deformation field and acquiring ground subsidence three-dimensional deformation field information having high temporal-spatial resolution. The method can acquire ground three-dimensional deformation information with a large range, a high precision and high temporal-spatial resolution.

Apparatus for splitting, imaging, and measuring wavefronts with a reference wavefront and an object wavefront. A wavefront-combining element receives and combines into a combined wavefront an object wavefront from an object and a reference wavefront. A wavefront-splitting element splits the combined wavefront into a plurality of sub-wavefronts in such a way that each of the sub-wavefronts is substantially contiguous with at least one other sub-wavefront. The wavefront-splitting element may shift the relative phase between the reference wavefront and the object wavefront of the sub-wavefronts to yield a respective plurality of phase-shifted sub-wavefronts. The wavefront-splitting element may then interfering the reference and object wavefronts of the phase-shifted sub-wavefronts to yield a respective plurality of phase-shifted interferograms. An imaging element receives and images the phase-shifted interferograms. A computer connected to the imaging element measures various parameters of the objects based on the phase-shifted interferograms. Examples of measurements include flow parameters such as the concentrations of selected gaseous species, temperature distributions, particle and droplet distributions, density, and so on. In addition to flow parameters, the displacement (e.g., the vibration) and the profile of an object may be measured.

The invention relates to optical coherent tomography method and the device, relating to the technical field of optical measurement and medical detecting instrument. The invention includes the following steps: (1) let the light beam to be measured generate reflected light and transmitted light which radiates to a detecting target object; the reflected light of the detecting target object returns from the original path and combines with the reflected light into one light beam which is then divided into two light beams; one of the light beam returns from the original path and the other is retained for a set light journey and then returns from the original path; the two returning light beams combine and generate interference and then enter a photodetector and generate relative electrical signals; (2) move the light beam irradiated to the detecting target object in all directions to scan the detecting target object; the adjustable light delaying element does one delaying operation each time the light beam is moved to a point; (3)repeat the operation to let the interferometric phase of the measured light correspond to different sections of the target object; (4)treat the interferometric photoelectric signals and send the treatment result to a computer for graphical analysis and display. The invention has the advantages that the device is convenient to move and small in size and the data is easy to process.

The invention discloses a PS-DInSAR ground surface deformation measurement parameter estimation method based on an optimal solution space search method. The method comprises the first step of obtaining a difference interferometric phase image sequence, the second step of extracting permanent scatterer points from the difference interferometric phase image sequence and constructing a Delaunay triangular network, the third step of calculating the second-order difference phases of each pair of adjacent PS points in a kth difference interferometric phase image, the fourth step of establishing an objective function to be optimized, the fifth step of searching for the objective function in a two-dimensional solution space, the sixth step of conducting local optimization on the objective function through the Levenberg-Marquardt algorithm, and the seventh step of solving the ground surface deformation quantity and an elevation error. According to the PS-DInSAR ground surface deformation measurement parameter estimation method based on the optimal solution space search method, signal sampling is not involved, so that the influence of all interference images on nonuniformity of time and space base lines is avoided, a high-precision result can still be obtained without priori knowledge, and a new thought and path are provided for ground surface deformation measurement.

The invention provides an interferometric system and method for quadrature detection of optical characteristics of a sample. The system includes a Mach-Zehnder interferometer providing a variable optical delay between light collected from the sample and reference light. The Mach-Zehnder interferometer has an output M×N coupler with N≧3 output ports. Two differential detectors, each having two input ports coupled to a different two of the N output ports of the M×N coupler, produce first and second electrical signals having an interferometric phase shift. A processor is provided for computing real and imaginary parts of a complex refractive index of the sample from the first and second electrical signals by using complex deconvolution.

The embodiment of the invention discloses a mine geological disaster dynamic identification and monitoring method based on multi-source remote sensing data. An optical remote sensing technology, an unmanned aerial vehicle airborne laser radar technology, an artificial corner reflector technology and a satellite-borne synthetic aperture radar technology are fused; an airborne laser radar can effectively remove ground vegetation; an accurate deformation profile and a ground fracture steep ridge distribution condition are obtained; archived high-precision optical image data are utilized to comprehensively analyze and describe a deformation development history, high-resolution remote sensing image change detection and feature recognition are utilized to search disaster signs, the airborne laser radar is introduced to acquire high-precision dem data, and topographic effect influence in InSAR data processing is effectively removed; an artificial corner reflector array is arranged, the numberof coherent points in a key area is increased, the coherent point distribution is optimized, and the interference phase unwrapping effect is improved; a traditional time sequence InSAR data processing technology is optimized, and a high-precision time sequence deformation curve is obtained by using CR-InSAR.

Techniques described herein are generally related to non-interferometric phase measurements of an optical signal. The various described techniques may be applied to methods, systems, devices or combinations thereof. Some methods for determining phase data of the optical signal may include transmitting the optical signal through a first optical element and obtaining first intensity data at a first focal plane of the first optical element by an optical sensor. Example methods may also include transmitting the optical signal through a second optical element. The second optical element may include a phase transformation mask. Example methods may further include obtaining a second intensity data at a second focal plane of the second optical element by the optical sensor and determining the phase data for the optical signal based on the first intensity data and the second intensity data.

The invention discloses an adaptive high-precision phase estimation method for an interferometric SAR, comprising the following steps of: structuring optimum weight vectors in combination with a Wiener filter theory, performing an eigen decomposition on an optimum covariance matrix composed of the optimum weight vectors to obtain a signal subspace and a noise subspace, adequately utilizing a corresponding pixel pair and the coherent information of the neighboring pixels thereof to structure a space spectrum function according to the orthogonality of the signal subspace and the noise subspace in a MUSIC (multiple signal classification) algorithm, and precisely estimating the interferometric phase between the corresponding pixels via a spectral peak searching. The optimum weight is obtained by only a Wiener filter without the need to determine a registration error and the direction thereof, thereby solving the problem of large computational burden in the traditional InSAR (interferometric synthetic aperture radar) interferometric phase estimation. The adaptive high-precision phase estimation method for the interferometric SAR disclosed by the invention is adaptive to the field of accurate surface parameter inversion of InSAR complex scene and the like.

The invention discloses an InSAR (Interferometric Synthetic Aperture Radar) block adjustment interferometric parameter calibration and control point densification method. The method comprises the following steps of: (1) acquiring untwisting results of all interferometric figures; (2) resolving orbital parameters, baseline parameters and interferometric phase offsets by adopting a block adjustment method according to the acquired interference figure untwisting results by utilizing homonymic connecting points in an image overlay region and ground control points within an image coverage range and encrypting the control points used for interferometric processing; and (3) reconstructing a DEM (Dynamic Effect Model) and manufacturing an orthophotomap. In the method, the block adjustment method is used for carrying out the interferometric parameter calibration of large-area multi-set InSAR data, which can effectively reduce the quantity of the ground control points required by the interferometric parameter calibration of the large-area multi-set InSAR data, improve the property of the interferometric parameter calibration, reduce the difference of inversion elevations at overedging parts of different interferometric data, improve the whole consistency and continuity of acquiring the DEM and the orthophotomap and encrypt out a large quantity of ground control points used for the interferometric processing.

A method for determining equivalence of elevation estimation precisions of satellite-borne multi-frequency and multi-baseline InSARs (interferometric synthetic aperture radars) comprises the following four steps: 1, giving an interferometric phase probability density function; 2, acquiring a maximum likelihood function of the multi-frequency and multi-baseline InSAR elevation estimation; 3, computing a CRLB (Cramer Rao lower bound) of the multi-frequency and multi-baseline InSAR elevation estimation; and 4, analyzing the equivalence of the elevation estimation precisions of the multi-frequency InSAR and the multi-baseline InSAR. Based on the interferometric phase probability density function, the CRLB of the multi-frequency and multi-baseline InSAR elevation estimation is computed to obtain the equivalence of the multi-frequency InSAR and the multi-baseline InSAR in an aspect of improving the elevation estimation precisions and provide an equivalent condition; the method provides a theoretic basis for design of a multi-frequency InSAR system or a multi-baseline InSAR system and the general analysis and provides a theoretic support for acquiring global and high-precision DEM (digital elevation model); and the method has a relatively high practical value and wide application prospect in the signal processing field.

The invention relates to a dam settlement monitoring method based on high-score image and lifting / lowering orbit InSAR, comprising the following steps: A. dam position information extract: obtaining the high-definition image data of the dam by satellite to obtain the precise geographic position and range of the target dam surface; B. PS-InSAR deformation rate acquisition: using N SAR images acquired by satellite in the same area, selecting one SAR image as a main image, and generating a differential interferometric phase map by using DEM and orbital data to obtain DEM error and deformation rate; C. settlement rate calculation of the fused lifting / lowering orbit: according to the reflection characteristics of different regions of the dam and the geometrical distortion region, fusing the deformation monitoring method of the lifting / lowering orbit InSAR with different visual directions to obtain high-precision settlement information; and D. dam settlement information extract; performing spatial superposition operation on the obtained fused high-precision deformation field and the dam data extracted from the high-score image to obtain the settlement deformation information on the dam surface, thereby realizing the settlement monitoring of the dam.

The invention discloses an onboard InSAR data processing method based on a BP algorithm and a time-varying baseline, and belongs to the field of radar imaging and InSAR signal processing. According to the onboard InSAR data processing method based on the BP algorithm and the time-varying baseline, the BP imaging algorithm is used for obtaining complex image data of double antennas, an interferometric phase representing the landform elevation is obtained through phase difference processing, phase filtering processing and phase unwrapping processing, and an accurate digital landform elevation is obtained through an elevation inversion method of the time-varying baseline. According to the BP imaging algorithm, an imaging area is divided into grids, and coherent accumulation in the azimuth direction is carried out on data obtained through pulse compression processing in the distance direction pulse by pulse to obtain high-accuracy complex image data according to motion tracks of phase centers of the antennas. According to the elevation inversion method of the time-varying baseline, parameters of the time-varying baseline change along the imaging grids in the azimuth direction point by point, namely, the parameters of the time-varying baseline change along the slow time, and the parameters of the time-varying baseline are determined by the space positions, at each moment, of the phase centers of the two antennas, and comprise the length of the time-varying baseline and the dip angle of the time-varying baseline.

The invention discloses an onboard SAL imaging method adopting along-track interference to inhibit the platform vibration. The method comprises the steps: pre-processing an echo signal, dividing a slow time subaperture and imaging the subaperture; processing an image of the subaperture by means of the interference, extracting an interferometric phase, and estimating the instantaneous speed of a platform in vibration; calculating a phase error caused by the vibration, and performing coarse compensation on the phase error; processing the phase-compensated data by means of PGA (Programmable Gain Amplifier) treatment to obtain a final imaging result. Based on an along-track multi-detector observing structure, the onboard SAL vibration inhibition and imaging method can effectively inhibit influences caused by the platform vibration, and realizes the high-resolution imaging of an onboard SAL azimuth.

The invention discloses an InSAR (interferometric synthetic aperture radar) imaging and altitude estimation method by iterative curved surface prediction. According to the InSAR imaging and altitude estimation method, raw echoed data of an InSAR are projected to a terrain altitude curved surface obtained from each iterative estimation to perform projection imaging by the aid of a back projection imaging algorithm so as to obtain an interferometric phase under the terrain altitude curved surface, high-altitude terrain inversion is performed by the aid of the interferometric phase, the terrain altitude curved surface is subjected to altitude compensation and multi-time iteration approximation, and the obtained terrain altitude curved surface is subjected to projection imaging and successive iteration approximation to estimate an actual terrain altitude, so that InSAR data imaging and altitude estimation integration is achieved, InSAR imaging and altitude estimation precision is improved, geometric distortion caused by terrain altitude variation is corrected, in other words, terrain geometric distortion is reduced, and a final InSAR imaging result and a final terrain altitude are obtained.

The invention discloses a high-resolution roll angle measuring method and device based on a heterodyne interferometric phase method. The device comprises a transverse Zeeman double-frequency laser and a beam splitter prism in an emergent light path of the transverse Zeeman double-frequency laser, and a first polarization analyzer and a first photoelectric receiver are arranged in a reflection light path of the beam splitter prism. A half-wave plate is arranged in a transmission light path of the beam splitter prism and is located in the middle of a plane mirror array, a phase delay sheet and a right-angle reflecting prism are arranged in a final emergent light path of the half-wave plate, and a second polarization analyzer and a second photoelectric receiver are arranged in a reflection light path of the right-angle reflecting prism. The first photoelectric receiver and the second photoelectric receiver are connected with a phase meter, and the output end of the phase meter is connected with an industrial personal computer. The superposition performance of acting on the polarized light is utilized when the half-wave plate and the plane mirror array are matched to be used, the half-wave plate is mounted in the plane mirror array and is used in common with the phase delay sheet, and roll angle measuring resolution is further improved.

The invention relates to a PS-InSAR technology-based historical settlement risk assessment method for surrounding environments along the subways. The method comprises the steps of employing N SAR images as input, registering all SAR images into a same mesh through an image registration method; selecting SAR images which are relatively small in time baseline and space baseline to generate an interferogram and removing an interferometric phase caused by topographic relief through a two-pass method; selecting candidate PS points (PSC) from the images, and compensating an error phase caused by an atmospheric change and an error phase caused by inaccurate orbit data by using information of the PSCs; and carrying out point-to-point analysis on all pixel points in the images by using the compensated phase information, identifying PS points again, and estimating deformation information and elevation error information thereof.

The invention discloses a multi-baseline and multi-band InSAR phase unwrapping method based on Chinese remainder theorem, which comprises the following steps: 1. respectively obtaining N multi-baseline InSAR interferograms, the ratio of any two baselines after registration of which is a rational number, and N multi-band InSAR interferograms; 2. calculating phase difference of adjacent pixels; 3. constructing a modulus ratio according to a wavelength ratio, thus constructing an integral cycle number ni and a residue number fi; 4. establishing congruence equations about a fuzzy number of fuzzy phase differential; 5. calculating p; 6. calculating the fuzzy number ki; 7. calculating interferometric phase differential after unwrapping, and 8. calculating the unwrapping phase Phiui of any pixel element in the interferograms. The method makes full use of the existing InSAR data, gives full play to the advantages of low processing difficulty and high processing accuracy of the technology of obtaining DEM through the multi-baseline and multi-band InSAR, effectively solves the problem of phase unwrapping of aliasing interference fringes in under-sampled situations in undulating terrain areas and improves the solvability and accuracy of the phase unwrapping.

Provided is a broadband synthetic aperture radar sub-band interferometric data processing method. The broadband synthetic aperture radar sub-band interferometric data processing method comprises the steps of (1) carrying out self-adaptive precise registration on main images and auxiliary images and resampling the auxiliary images, (2) optimizing sub-band frequency spectrum positions and broadband, (3) carrying out band-pass filtering on the main images and the auxiliary images, (4) generating sub-band interferograms and sub-band difference interferograms, (5) carrying out phase compensation on a reference plane and a DEM, and (6) carrying out stack processing on the sub-band difference interferograms. According to the broadband synthetic aperture radar sub-band interferometric data processing method, absolute radar interferometric phases can be obtained without phase unwrapping under most conditions, digital terrain maps or earth surface deformation maps can be directly obtained through transformation, and error diffusion caused by phase unwrapping mistakes can be eliminated. The broadband synthetic aperture radar sub-band interferometric data processing method is especially suitable for digital topographic mapping in high mapping regions, monitoring on landslides with large deformation velocity and monitoring on mine collapse.

A target detection method based on ATI-SAR image amplitude and phase information fusion includes the following steps: correcting the amplitude offset and phase deviation of a dual-channel ATI-SAR image using a coarse-to-fine image registration technology; carrying out compound interferometric treatment on the dual-channel image to extract the interference amplitude and phase components, and acquiring interferometric phase components characterizing the target-sea surface relative radial motion in an interferometric phase domain through sea clutter equivalent interferometric phase estimation and cancellation based on automatic indexing and domain decomposition; and establishing an interferometric amplitude and phase 'modulus' related criterion, and detecting a target using an adaptive threshold algorithm in an MIMP feature domain. Fine registration of a dual-channel image can be realized under the condition of low precision of parameters such as platform speed and baseline length. Through full consideration and removal of interference caused by random fluctuation movement of background clutter, a universal MIMP criterion is established. The target-clutter contrast is enhanced by making effective use of interferometric amplitude and phase information. The ability to detect multiple targets or weak targets in a complex scene is improved.

The invention discloses an interferometric phase microscopy one-step imaging system and method based on two-step phase shift, and adopts the technical scheme that based on a typical Mach-Zehnder interference light path, lateral displacement beam splitting mirrors are adopted to perform light splitting on sample light and reference light respectively, a wave plate is utilized as a phase shifter, and two interference figures can be acquired at the same time through single exposure, and phase imaging can be realized quickly through corresponding phase recovery operation, and a spatial form structure of a phase body is further deconstructed. The interferometric phase microscopy one-step imaging system and method are suitable for all interferometric phase microscopy imaging systems, such as traditional coaxial interference, off-axis interference and slight off-axis interference, and have high practical value and wide application prospect in the aspect of phase microscopy, particularly in the field of application and identification of biological cell morphology.

The invention discloses an interference SAR data imaging and elevation estimation method. On the basis of the back-projection imaging theory, by adopting the corresponding relation between interferometric phase and terrain elevation in the interference SAR back-projection algorithm imaging process, and by using the principle that the minimum interferometric phase is obtained when the imaging space terrain elevation is the real terrain elevation, the terrain elevation corresponding to the minimum interferometric phase is found by the steepest descent method, and interference SAR data is projected to the optimal imaging space terrain elevation which is estimated and obtained by the steepest descent method, for the purpose of imaging. In this way, synchronous processing of interference SAR echo data imaging and elevation estimation is realized. Compared with the prior art, the invention reduces interference SAR image distortion effect which may be caused due to terrain elevation fluctuation, and improves the interference SAR imaging image quality and the terrain elevation estimation precision under the condition of fluctuating terrain elevation.

The present invention discloses a method for fusion unwrapping of spaceborne InSAR long and short baselines. The method comprises: employing a spaceborne InSAR system interference processing flow to respectively perform inversion of digital elevation models (DEM) of a long baseline and a short baseline; employing three-dimensional coordinates of ground points corresponding to each pixel point in the images of the long baseline and the short baseline, combining data such as satellite parameters, offset and the like, calculating a vertical baseline and an effective baseline respectively corresponding to the images of the long baseline and the short baseline, selecting an appropriate reference ground, and calculating the long baseline interferometric phase and the short baseline interferometric phase corresponding to the reference plane; and finally, taking correlation coefficients, reference plane phases, baselines and the like obtained before as auxiliary data, employing a maximum likelihood method, and performing fusion processing of the long baseline phase data and the short baseline phase data so as to obtain a long baselined unwrapping phase with higher precision. The method for fusion and unwrapping of the spaceborne InSAR long and short baselines is used in the multi-baseline interference processing, the maximum likelihood method is employed to fuse the long and short baseline unwrapping phases to obtain high-quality DEM; and the method for fusion and unwrapping of the spaceborne InSAR long and short baselines can be also used for fusion processing of data such as interferometric phase and elevation, etc.

The invention discloses a radar synthetic phase unwrapping method based on a branch-cut method and surface fitting. According to the main idea, the method comprises: conjugated multiplication of image data of an SAR image after image registration and image data of the SAR image after image registration is carried out to obtain an interferometric phase diagram and then obtain a pseudo association coefficient of the interferometric phase diagram; a pseudo association coefficient threshold value of the interferometric phase diagram is set to obtain a first quality area diagram and a second quality area diagram, and phase unwrapping is carried out on the first quality area diagram by using a branch-cut method to obtain an unwrapping phase of the first quality area diagram; fitting of the unwrapping phase of the interferometric phase diagram is carried out by using a polynomial surface fitting method to obtain a coefficient column vector of a polynomial fitting function of the interferometric phase diagram and an unwrapping phase curve surface with an error of the interferometric phase diagram; and the unwrapping phase curve surface with an error of the interferometric phase diagram is optimized by using a genetic algorithm, thereby obtaining an optimized unwrapping phase curve surface of the interferometric phase diagram. Therefore, the final unwrapping phase of the interferometric phase diagram is obtained.

The invention discloses a preprocessing and adaptive genetic simulated annealing algorithm-based phase unwrapping method. The method includes the following steps that: adjacent dipole pair residues within a distance threshold value R are pre-processed; the residues are optimized and combined through adopting an adaptive genetic simulated annealing algorithm; and each pair of combined positive and negative residues are connected together through branch-cut lines in an interferometric phase image, and the branch-cut lines are bypassed through using a flood-fill method, so that phase unwrapping can be performed. According to the preprocessing and adaptive genetic simulated annealing algorithm-based phase unwrapping method of the invention, a part of dipole pair residues are pre-processed through a pre-processing method of the variable distance threshold value R, so that the lengths of the branch-cut lines can be formed; the residues are optimized and combined through the adaptive genetic simulated annealing algorithm, so that the total length of the branch-cut lines can be formed, and closed regions are few, and total computation time is little; and since the set branch-cut lines are short, accumulative errors around the branch-cut lines can be decreased when unwrapping is performed, and therefore, unwrapping accuracy can be improved, and the number of unwrappable islands can be decreased.

The invention discloses an atmospheric phase screen extraction method based on ground-based SAR (synthetic aperture radar) interference. Atmospheric phase is extracted according to a ground-based radar differential interferometric phase model on basis of a least squares fitting linear deformation and time-space filtering method. The ground-based radar differential interferometric phase model has a full consideration of the ground-based radar imaging mechanism and the differential interference theory so as to extract an atmospheric phase screen. A PS (permanent scatterer) point selection method of three levels, amplitude dispersion index, correlation index and phase stability, is provided, the atmospheric phase screen of radar data of each scene is finally obtained by means of Kriging interpolation, and accurate extraction of the phase generated under atmospheric interference has an important role on improving radar interferometric precision. Correctness of the method is verified by measured dam data, and the method is of certain actual application value and universality.