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169 results about "Physical optics" patented technology

In physics, physical optics, or wave optics, is the branch of optics that studies interference, diffraction, polarization, and other phenomena for which the ray approximation of geometric optics is not valid. This usage tends not to include effects such as quantum noise in optical communication, which is studied in the sub-branch of coherence theory.

Electromagnetic scattering simulation method based on parallel moment method and physical optics mixing

The invention discloses an electromagnetic scattering simulation method based on parallel moment method and physical optics mixing to mainly solve the problem that when electrically large models are processed in the prior art, the simulation efficiency of electromagnetic scattering and the precision are low. The electromagnetic scattering simulation method comprises the steps that a rough surface power spectrum and rough surface parameters are input, and a rough surface is simulated based on the Monte Carlo method; geometric modeling is carried out on a radar target through 3dsMax software, and the subdivided radar target is output; a combined model is formed by combining the rough surface and the radar target, the rough surface is divided into a physical optics area, and the radar target is divided into a parallel moment method area; induced currents on the rough surface and induced currents on the surface of the radar target are obtained; a far scattered field of the combined model is calculated based on the induced currents on the surface of the combined model, a radar cross section of the combined model is obtained, and simulation between the rough surface and the combined electromagnetic scattering of the radar target is achieved. According to the electromagnetic scattering simulation method, the memory consumption is little, the simulation efficiency is high, and the electromagnetic scattering simulation method can be used in the study on the rough surface and the radar target combined electromagnetic scattering character in the field of national defense and the civil using.
Owner:XIDIAN UNIV

Invisible apparatus and design based on geometrical optics

InactiveCN101299079AAchieve optical invisibilitySimple structureBundled fibre light guidePhysical opticsImage transfer
The present invention provides a concealing device which is based on geometric optics and a design thereof, and relates to the field of optical concealing technique. According to the principle of physical optics, the light beams are converged with a convex lens. The cross-sectional area of the light beam is changed. The incidence light at the front of the object can be converged through the convex lens and transferred to the backside of the object through an image transferring channel, and is changed to the former incidence ray through radiation. The effect of concealing the visible light is obtained. The core of the device is that the concealing device is composed of at least one group of object group 1 which can be permeated with light and focus the light, a light beam transmission component 2 which is provided between the focusing object group 1 and a concealing area 3. The device is designed with an imaging formula of the convex lens to obtain the effect of optical concealing the visible light. The concealing state of the device is sustained without exterior power. The exterior exposed part of the device is fewer. Compared with the optical physical concealing device, the concealing device according to the invention has the characteristics of simple structure, easy manufacture, low cost and wide application area.
Owner:上海市第二中学

Rapid calculation method for electromagnetic scattering of ultra-high-speed target in thin atmosphere

ActiveCN107942309AEnabling Electromagnetic Scattering CalculationsWave based measurement systemsPhysical opticsStream flow
The invention discloses a rapid calculation method for electromagnetic scattering of an ultra-high-speed target in a thin atmosphere. The rapid calculation method comprises the steps of: plasma equivalent layered medium model modeling, which is implemented by analyzing streaming flow field data f a hypersonic speed target by utilizing an isotimic-surface extraction algorithm, and establishing a plasma equivalent layered medium model; ray tracing and field intensity tracing in layered media, wherein the tracking is implemented by simulating the propagation process of electromagnetic waves in the layered media by utilizing rays, performing field intensity tracing along propagation paths of the rays, and acquiring electric field information of the rays at intersection points in the layered media; and modeling of a far-region scattering field for a layered media coated target, wherein the modeling is implemented by modeling electromagnetic scattering features of a multilayer-medium-coatedtarget by adopting an shooting and bouncing ray method in the case of high-frequency electromagnetic wave incidence, calculating scattering contributions of emergent rays in the direction of a radar receiver by utilizing a physical optics method for the emergent rays, and acquiring a total scattering field and RCS information. The rapid calculation method has the advantage of expanding the range of applicability.
Owner:SHANGHAI RADIO EQUIP RES INST

SBR and PO technology-based strong scattering center calculation method

The invention belongs to the signal characteristic control technical field and relates to an SBR and PO technology-based strong scattering center calculation method. The calculation method comprises the following steps that: hotspot calculation is performed through ray tracing and physical optics; a distribution diagram which can indicate the radar cross section (RCS) contribution of each surface element of a target surface is obtained; and strong scattering parts can be located through comparing hotspot diagrams. Compared with a low-frequency method, and according to the SBR and PO technology-based strong scattering center calculation method, SBR and PO methods are adopted to calculate target hotspots, and therefore, high efficiency can be realized; hotspot contribution is attached to the surface of a 3D model, and therefore, the strong scattering contribution parts can be analyzed intuitively. The SBR and PO technology-based strong scattering center calculation method of the invention can trace separated two-times and three-times strong coupling structures. Strong multiple-times scattering which is generated through the coupling of separated parts on a target is usually difficult to discover, while, hidden strong scattering structures can be found out through the hotspot diagrams.
Owner:中国航天科工集团第二研究院二〇七所

Method for calculating near-field radar echo characteristics of moving object based on beam decomposition and local irradiation

InactiveCN103777186ASolve the major technical problems of near-field radar echoRadio wave reradiation/reflectionFrequency spectrumRadar equation
The invention discloses a method for calculating near-field radar echo characteristics of a moving object based on beam decomposition and local irradiation. The method comprises the steps of determining a coordinate system of radar or a detector, a coordinate system of the moving object and transformation relation between the coordinate systems; determining a relative speed coordinate system of the detector and the object, thereby acquiring a miss distance; providing radar beam description so as to decompose an incident beam, carrying out surface element subdivision on the object, determining the local irradiation area, and judging surface element shielding; meeting a far-field condition by a sub-beam irradiation surface element, and superimposing by using a physical optics method to acquire a backward radar cross section; and acquiring a time series of the power of near-field radar echoes by using a radar equation and the corresponding spectral characteristics. A far-field calculation method is expanded to near-field calculation by using the characteristic that beam decomposition and physical optics are similar to each other locally, and the time series of the power of the near-field radar echoes and the corresponding spectral characteristics. According to the method disclosed by the invention, the far-field calculation method is expanded to the near-field calculation by using the characteristic that the beam decomposition and the physical optics are similar to each other locally, and the time series of the power of the near-field echoes and the corresponding frequency spectrum are calculated by the radar equation.
Owner:XIDIAN UNIV

Wind turbine fan radar echo signal Doppler spectrum solving method

The invention discloses a wind turbine fan radar echo signal Doppler spectrum solving method. The wind turbine fan radar echo signal Doppler spectrum solving method comprises the following steps: first, determining a rotating angle interval for calculating a blade static RCS by utilizing the 'Nyquist sampling theorem' according to the derived equivalence relation between blade dynamic radar cross section fluctuation frequency and blade radar echo signal Doppler frequency; then, respectively calculating the RCS of a wind turbine blade at various sampling angles by utilizing a mixed algorithm consisting of a physical optics method and an equivalent electromagnetic current method, so that a blade dynamic RCS is obtained based on a 'quasi-static method'; finally, performing discrete short time Fourier transform on the obtained blade dynamic RCS, and solving to obtain the Doppler spectrum of the blade dynamic RCS, namely, the Doppler spectrum of the blade radar echo signal. According to the wind turbine fan radar echo signal Doppler spectrum solving method, a new method and a new way can be provided for effectively identifying a wind turbine target by a radar station, and theoretical basis can also be provided for the aspects, such as electromagnetic scattering reduction of a wind power plant, and wind power plant clutter extraction and inhabitation of the radar station.
Owner:CHINA THREE GORGES UNIV

Visual tracing scattering analysis method of inhomogeneous medium

The invention discloses an efficient calculation method of a radar scattering cross section of an inhomogeneous medium wrapped target. The method comprises the following steps: firstly equalizing the inhomogeneous medium into a layered homogeneous medium according to electromagnetic parameters; setting up a lighting model and selecting a three-dimensional viewpoint in an OpenGL (open graphics library) and inputting the three parts of information into a graph hardware processor; accomplishing the automatic shielding of a three-dimensional target by using the graph hardware processor; outputting a real-time target image and visible pixel information displayed on a computer screen after the automatic shielding, wherein the visible pixel information includes brightness values (R,G,B) and three-dimensional coordinates (x,y,z) of pixels; displaying medium interfaces at which rays arrive layer by layer in the OpenGL according to the direction of incident electromagnetic waves; extracting the brightness and the coordinate information of the pixels; determining the reflection and refraction of the rays by combination of the electromagnetic parameters at two sides of the interface, so as to trace the direction of the rays and determine the incidence direction of incidence electromagnetic waves of the pixels of the target when the rays arrives at a target body; in a loss medium, synchronously calculating the attenuation of each ray on a transmission journey; and finally, calculating the radar scattering cross section of the inhomogeneous medium wrapped target according to integrals of a physical optical field and a boundary diffraction field. The method has the advantages that a novel method for calculating radar scattering characteristics of the inhomogeneous medium based on graphic display is provided, so that the defects that in a traditional calculation method, a large-sized medium cannot be calculated, and control in manual mode is difficulty are overcome.
Owner:SHANGHAI INST OF ELECTROMECHANICAL ENG

Method for obtaining radar scattering area

The invention discloses a method for obtaining a radar scattering area. The method is used for resolving the technical problem that an existing method for obtaining the radar scattering area is low in speed. According to the technical scheme, firstly, a radar scattering model is set up, a firing line is used for simulating an attack direction, association attributes of components are defined, and related data of firing line meshes and the like of the components are obtained; secondly, a projected coordinate system is set up, the data are converted into the projected coordinate system, and RCS calculation is carried out on the related data; at last, real parts and imaginary parts are respectively accumulated to obtain the radar scattering area. Due to the fact that the radar scattering area is obtained by means of a physical optical method and a planar firing line method, the planar meshes are laid on a quadrilateral finite element projected model, 1-N firing lines are produced randomly in units of the planar meshes, and surfaces of the components are scanned through the 1-N firing lines to obtain geometric description data of the radar scattering area. Step sizes of the meshes are regulated according to different precision requirements, radar scattering areas of different precisions are obtained, and the speed for obtaining the radar scattering area is increased.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Time domain physical optics algorithm based on CPU (Central Processing Unit) and GPU (Graphics Processing Unit) hybrid asynchronous parallel way

The invention discloses a time domain physical optics algorithm based on a CPU (Central Processing Unit) and GPU (Graphics Processing Unit) hybrid asynchronous parallel way. The time domain physical optics algorithm comprises the following steps: 1, performing modeling through 3Dmax, and performing subdivision through triangular surface elements, wherein a derived model is in an OBJ format; 2, synchronously reading usable information such as vertex coordinates and a vertex quantity of the triangular surface elements in a model file (1), vertex numbers and a surface element quantity of the surface elements in the model file (2) and an incident electric field (3) respectively on three threads in an MPI parallel way; 3, accelerating the whole process in parallel through OpenMP; 4, transmitting data such as a Gaussian node array and a triangular surface element array into a GPU, accelerating a Gaussian integral value operation by the GPU to obtain a scattered field, and transmitting the scattered field into a CPU; and 5, transforming a scattered field time domain into a frequency domain through a Fourier transform, and dividing the frequency domain by an incident electric field frequency domain to obtain an RCS (Radar Cross Section) array. Through adoption of the time domain physical optics algorithm, time is saved greatly when a transient scattering calculation amount of an electrically large object is large.
Owner:XIDIAN UNIV

Method for calculating radar scattering cross section of metal cylindrical calibration body

The invention provides a method for calculating a radar scattering cross section of a metal cylindrical calibration body, which comprises the following steps of: pre-setting the size of the metal cylindrical calibration body; calculating a first total scattering electric field of the pre-set metal cylindrical calibration body by adopting MoM numerical value analysis; obtaining a first physical optical scattering component of the pre-set metal cylindrical calibration body by utilizing a PO formula; calculating a first surface wave scattering component of the pre-set metal cylindrical calibration body according to the first total scattering electric field and the first physical optical scattering component, and carrying out normalization processing of the first surface wave scattering component to obtain a first normalized surface wave scattering component; modelling the first normalized surface wave scattering component by adopting a CE model to obtain corresponding functions of the first normalized surface wave scattering component and frequency; obtaining a second physical optical scattering component of the metal cylindrical calibration body to be calculated by utilizing the PO formula; and calculating to obtain a second total scattering electric field of the metal cylindrical calibration body to be calculated by utilizing the shrinkage ratio principle according to the corresponding functions and the second physical optical scattering component.
Owner:BEIHANG UNIV

Method for detecting micro lens fixed focus based on grating shear interference detection system

The invention relates to a method for detecting micro lens fixed focus based on a grating shear interference detection system. The method belongs to the technical field of optical detection. The method achieves fixed focus measurement of a micro lens by use of fringes generated by zero-grade and first-grade diffraction light interference of Ronchi grating: when a parallel light passes through the Ronchi grating, zero-grade and first-grade diffraction light spots are generated due to a diffraction effect of the grating; according to a phase change in front of a diffraction light wave, when the grating is arranged on a micro lens focal plane, interference fringes in a light spot overlapping region can be avoided; when the grating is arranged at an out-of-focus position, the light spot overlapping region generates the interference fringes due to phase difference; defocusing amount of the grating can be calculated by a fringe periodic change at different defocusing positions, and thus the fixed focus measurement of the micro lens can be achieved. According to a physical optical theory, the method analyzes the relation between grating defocusing amount and a fringe cycle quantitatively, calculates the defocusing amount twice through difference of fringe cycles when the grating defocuses twice before and after focusing, thereby achieving fixed focus of the micro lens and array elements.
Owner:INST OF OPTICS & ELECTRONICS - CHINESE ACAD OF SCI

Method for analyzing and quantitatively estimating influence of wind farm on weather radar based rainfall

The invention provides a method for analyzing and quantitatively estimating influence of a wind farm on weather radar based rainfall. The method comprises the following steps: the relative distance between the wind farm and the radar is calculated on the basis of longitude and latitude position information of the radar and the wind farm and compared with a line-of-sight distance of the radar; echo signal intensity of wind turbines is calculated and compared with sensitivity of a radar receiver; the irradiation range of radar beams is calculated by means of terrain height of an area where the wind farm and the radar are located and in combination with parameters such as radar elevation, beam width and the like; the length of the wind turbine in the radar irradiation range is calculated, RCS of the wind turbine is calculated with an analytical model based on a physical optics method, and then radar reflectivity is obtained; influence of a wind turbine model and a wind turbine distribution mode on the radar reflectivity is analyzed; the rainfall of the wind farm area is calculated according to the relation between the radar reflectivity and the rainfall. The method is completed with the analytical model based on the physical optics method and has the advantages of high calculation speed, relatively simple processing steps and the like.
Owner:CIVIL AVIATION UNIV OF CHINA

Method of measuring influence of radome on antenna array direction-finding performance

The invention discloses a method of measuring the influence of a radome on the antenna array direction-finding performance. The method comprises the steps of determining various parameters in an antenna array, including antenna coordinates, antenna equivalent aperture data and radome geometry and the like; calculating the amplitude and phase of an electric field generated by each antenna at a far region outside the radome by using a physical optics method; calculating the insertion phase delay of an arbitrary antenna unit in the antenna array; calculating the phase error, that is the difference of the insertion phase delay between two antennas; and calculating an average value of the phase errors of any two antennas in the antenna array system, and finally calculating the difference between the phase error of the two antennas and the average value, that is the phase inconsistency of the radome, for measuring the influence of the radome on the antenna array electrical performance. Compared with the prior art, the invention has the advantages of requiring no knowledge of the working pattern or radiation characteristics of the antenna array in the radome, reducing the complexity and amount of calculation, facilitating requirements of special systems and so forth.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

Rough surface and multi-target composite scattering simulation method based on iterative physical optics

The invention belongs to the technical field of radar electromagnetic simulation, and discloses a rough surface and multi-target composite scattering simulation method based on iterative physical optics. The method comprises the following steps: inputting a rough surface power spectral density function and a roughness parameter, obtaining a rough surface geometric contour by the Monte Carlo method; using the simulation software FEKO to geometrically model the targets; adding the geometric models of the targets to the rough surface model to generate a composite model; using the physical opticsmethod to calculate the surface induced electromagnetic current directly scattered by the rough surface and each target; calculating the surface-induced electromagnetic current between the rough surface and the targets and between the targets according to the iterative strategy and Huygens principle; obtaining a far-field total scattering field of the composite model by the Huygens principle; andobtaining a two-station radar scattering coefficient of the composite model based on the total scattering field and the incident field of the composite model. The rough surface and multi-target composite scattering simulation method based on iterative physical optics has the advantages such as low memory requirement, high simulation efficiency and strong versatility of the simulation method.
Owner:XIDIAN UNIV

Dust removal device of physical optical experimental instrument

The invention discloses a dust removal device of a physical optical experimental instrument, and relates to the technical field of dust removal devices. A clapboard is fixedly connected to the bottomof an inner cavity of a dust removal box, a supporting plate is fixedly connected between the right side of the clapboard and the inner wall of the dust removal box, and two supporting bases are fixedly connected with the top of the supporting plate; a first rotating shaft penetrates through the space between the two supporting bases, the two ends of the first rotating shaft are fixedly connectedwith rotating blocks, a first bump is fixedly connected to the surface of each rotating block, swing rods are rotatably connected with the portions, located below the rotating blocks, of the surfacesof the supporting bases through rotating shafts, and one end of each swing rod is slidingly connected with the corresponding first bump through a second sliding groove. According to the dust removal device of the physical optical experimental instrument, sliding blocks can be controlled to swing left and right by utilizing the sliding connection between second bumps on the surfaces of the slidingblocks and the swing rods through the first sliding grooves, the sliding blocks drive a bristle brush plate, and dust particles falling on an inclined plate can be pushed to a filter plate.
Owner:杨曙铭

Method for rapidly extracting electrical property parameter of metal truss-type radome

The invention discloses a method for rapidly extracting the electrical property parameter of a metal truss-type radome. The method includes: building geometric models of the antenna equivalent aperture, the metal truss and the medium skin firstly; then calculating the magnetic field of the metal truss surface through the formula of Stratton-Chu and the induced current of the metal truss light area through the physical optical method; calculating the incident electric field and the magnetic field of any point on the medium skin inner surface through the formula of the Stratton-Chu and the transmission coefficient of the point, obtaining the electric field and the magnetic field of the skin outer surface according to the incident electric field and the magnetic field, and calculating the equivalent current and magnetic current of the outer surface; and respectively calculating the induced current of the metal truss and the far field of the induction electromagnetic current on the medium skin outer surface in the observing direction, calculating the gain pattern and obtaining the electrical property parameter of the metal truss-type radome. Compare with the prior art, the method for rapidly extracting the electric property parameter of the metal truss-type radome has the advantages of being high in precision and calculating speed.
Owner:NANJING UNIV OF SCI & TECH
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