48 results about "Snell's law" patented technology

The invention discloses a monocular and binocular cooperative localization and mapping method and device for underwater refraction compensation, and the method comprises the steps: extracting checkerboard angular points, compensating an underwater light path through employing a two-time vector correction model based on a Snell law, and precisely calibrating the internal and external parameters of a binocular camera. According to the method, an underwater real light path is effectively restored, and calibration errors caused by medium refraction are remarkably reduced. Then epipolar correction is performed on the corrected left and right images, so that the geometric consistency of stereo matching is ensured; and finally, monocular and binocular poses are fused, and seven-degree-of-freedom similarity transformation global alignment is applied, so that the problem of monocular scale uncertainty is effectively solved, and high-precision and high-robustness three-dimensional mapping is realized by means of binocular real scale introduction. Key links such as camera pre-calibration, refraction compensation, image correction, monocular tracking, binocular depth measurement, scale alignment and the like are connected in series to form an integrated process, so that the underwater vision positioning and mapping precision is improved.

The invention discloses an underwater target identification and positioning method based on fusion of a physical model and deep learning, and belongs to the technical field of computer vision, and the method comprises the steps: carrying out the transmissivity estimation and physical restoration of a collected underwater monocular image according to an underwater light propagation model, and carrying out the image correction; key feature points are extracted, and high-quality matching point pairs are screened in combination with the joint similarity; further deriving a basic matrix through the high-quality matching point pairs meeting the epipolar geometric constraint relation, solving an essential matrix, and obtaining relative attitude parameters between the cameras in combination with weighted re-projection-LM optimization; and finally, refraction correction triangulation is carried out according to the Snell's law, pixel-level fusion is carried out after scale normalization and space alignment are carried out on the refraction correction triangulation and dense depth output by the MiDaS, three-dimensional space coordinates of the target are inverted, and high-precision recognition and positioning of the underwater target are achieved. The system is light in structure, efficient in calculation, suitable for being integrated on various underwater autonomous or remote control robot platforms and used for tasks such as target recognition, tracking and positioning.

The invention discloses an extremely shallow water blue-green laser sounding dynamic refraction vision correction method, which belongs to the technical field of marine surveying and mapping and underwater detection, is used for laser refraction correction, and comprises the following steps: synchronously acquiring binocular images and inertial measurement unit attitude data, and generating a three-dimensional point cloud; according to a light spot area in the laser emission angle index point cloud, fitting a micro-tangent plane to obtain a water surface original normal vector; calculating a confidence coefficient weight according to the image texture definition, and iteratively calculating an optimal estimation normal vector based on the original normal vector and the weight; calculating a real incident angle according to the optimal estimation normal vector and the laser emitting direction; calculating the direction vector of the underwater refracted light according to the Snell's law; and calculating the underwater three-dimensional coordinates of the target point by combining the propagation distance of the laser in the air and the water and the emission origin coordinates. According to the method, the visual confidence is introduced, so that the problem of data failure when the traditional visual sounding encounters water surface reflection, glare or broken waves is solved, and the robustness under the complex sea condition is remarkably improved.

The invention belongs to the technical field of underwater vision measurement, and relates to an underwater binocular vision system refraction parameter self-calibration method, which comprises the following steps of: firstly, constructing a space equation containing a water body refractive index, a refraction interface normal vector, an interface distance and a light path coefficient based on a Snell law; constructing a generalized state vector including an environment parameter, a structure parameter and a path parameter; a system residual equation is established by using different-plane light intersection constraint of binocular vision, and nonlinear iterative least square solution is carried out by constructing a generalized Jacobian matrix so as to realize adaptive calibration of an underwater vision system; according to the method, on the premise that water body parameters do not need to be predicted and high-precision mechanical calibration is not needed, the water body refractive index and the system structure parameters are synchronously solved, self-adaptive calibration of the underwater vision system is achieved, and the three-dimensional measurement precision and robustness in the complex water environment are remarkably improved.

According to the indirect image encryption method based on the polarization multiplexing metasurface, the used phase gradient metasurface is composed of nanometer bricks with singular point characteristics and mirror image structures of the nanometer bricks, when left-hand circularly polarized light and right-hand circularly polarized light are incident, the corresponding structures of the nanometer bricks play a role respectively, two holograms are constructed in a far field, and polarization multiplexing is achieved; on the basis that two structures are arranged in the column direction to form a super unit, when x-ray polarized light is incident, light is subjected to non-abnormal reflection through the generalized Snell law, required RCP and LCP are filtered out, and emergent light is superposed to generate vector light; performing condition limitation on the azimuth angle of the vector light through a simulated annealing algorithm to obtain two encrypted patterns; the encrypted pattern needs to be obtained by analyzing the polarization of the emergent light to obtain a corresponding Stokes parameter and then constructing a decryption function related to the Stokes parameter for calculation and analysis; therefore, the metasurface for realizing polarization multiplexing and indirect encryption functions of incident light in different polarization states is constructed.

The invention discloses an underwater topographic measurement method. In order to solve the problems that in an existing physical model experiment, contact type measurement destroys the terrain, optical measurement is interfered by refraction, and acoustic equipment is high in cost, a measurement scheme integrating flight time correction and refraction geometric compensation is provided. According to the method, a depth camera is arranged to collect scoured terrain point cloud data in real time, Gaussian filtering denoising and outlier elimination are carried out in sequence, a double-medium light path correction model is constructed based on the Snell law, flight time errors caused by light velocity differences and axial and radial offsets caused by air-water interface refraction are calculated respectively, and the accuracy and the reliability of the two-medium light path correction model are improved. And finally, high-precision three-dimensional terrain coordinates are generated. According to the method, low-cost hardware of the depth camera is combined with algorithm compensation, errors caused by refraction and light velocity differences in underwater topographic survey are reduced, experimental results show that the average relative error is smaller than 3%, non-contact and high-precision real-time monitoring of the physical model scoured topography is achieved, and reliable technical support is provided for hydraulic structure safety assessment.

The present application relates to the technical field of optical aspheric surface, especially points to a kind of free curved surface characterization method based on CGH lens zero position compensation detection optical path, with the detection of free curved surface as the guide, based on zero position compensation detection principle, according to ray tracing method, Snell's law, diffraction principle and equal optical path principle, using the parameters required by interferometer incident wave front as plane wave, compensator as single CGH lens zero position compensation detection system indirectly characterizes free curved surface shape, by using XY polynomial and Zernike standard phase polynomial, the mathematical description of free curved surface is realized in design stage can determine its measurement scheme, and according to the characterization method self-defined a kind of aspheric surface type, called zero position free curved surface.The free curved surface characterization method improves the degree of freedom of free curved surface shape and the feasibility of zero position compensation method, reduces the detection difficulty of free curved surface shape, realizes the function of zero position free curved surface design can be detected.

The application discloses an IMU light path structure based on multiple super surfaces, and the light beam generated by a laser 1 is divided into three mutually perpendicular light beams after the action of a beam splitting super surface 3, and then is converted into circularly polarized light and linearly polarized light by a polarization conversion beam splitting super surface 4, and is used for pumping and detection of a nuclear magnetic resonance gyroscope 5 respectively. The beam splitting super surface 3 is composed of polarization-insensitive cylindrical nanorods, and the incident light is split and corresponding deflection is generated by combining the generalized Snell law. The polarization conversion beam splitting super surface 4 is composed of polarization-sensitive rectangular nanorods and polarization-insensitive cylindrical nanorods, the rectangular nanorods are used for converting linearly polarized light into circularly polarized light, and the cylindrical nanorods maintain the linear polarization characteristics and realize light beam splitting and direction adjustment. The application adopts a single laser configuration, realizes efficient light field regulation and control based on super surfaces, avoids the problem that a traditional IMU light path system depends on multiple lasers, reduces the system volume, complexity and energy consumption, improves the stability and integration, and is suitable for high-precision inertial navigation applications.

The application discloses a method for correcting the vision of laser refraction in extremely shallow water, and belongs to the technical field of marine surveying and mapping and underwater detection, and is used for laser refraction correction. The method comprises the following steps: synchronously collecting binocular images and inertial measurement unit attitude data, and generating three-dimensional point clouds; indexing a light spot area in the point clouds according to a laser emission angle, fitting a micro tangent plane, and obtaining an original normal vector of the water surface; calculating a confidence weight according to the image texture definition, and iteratively calculating an optimal estimated normal vector based on the original normal vector and the weight; calculating a real incident angle according to the optimal estimated normal vector and a laser emission direction; calculating a direction vector of underwater refracted light according to Snell's law; and combining the propagation distances of the laser in the air and in the water and the emission origin coordinates, and calculating three-dimensional coordinates of a target point on the water bottom. The application introduces visual confidence, solves the problem of data failure of traditional visual depth measurement when encountering water surface reflection, glare or broken waves, and significantly improves the robustness under complex sea conditions.

Disclosed in the present application are a Huygens-metasurface-based transparent transmission unit and a manufacturing method therefor, and a Huygens-metasurface-based transparent transmission array. The unit comprises intermediate dielectric layers, a first metal layer, and a second metal layer. The array comprises a plurality of Huygens-metasurface-based transparent transmission units that are arranged in a rectangular layout. The method comprises: on the basis of the generalized Snell's Law, determining the phase distribution of a Huygens metasurface unit, and adjusting parameters of a double-arc structure, so as to obtain double-arc structure parameters; on the basis of the structure parameters, manufacturing metal layers and performing etching to make the metal layers form on surfaces of PET layers; and positioning a target on each PET layer, and by means of an optically clear adhesive, bonding onto glass the PET layers with the metal layers, so as to manufacture a transparent transmission unit. The embodiments of the present application can achieve high transmittance of electromagnetic waves and achieve easy deployment on existing windows, and extend the wireless-signal reception range in specific areas. The Huygens-metasurface-based transparent transmission unit and the manufacturing method therefor, and the Huygens-metasurface-based transparent transmission array, as provided in the present application, can be widely applied in the technical field of electromagnetic metasurfaces.

The invention discloses an underwater binocular camera calibration method based on laser assistance, and the method comprises the steps: firstly constructing an underwater stereoscopic vision binocular refraction-removing imaging model according to the Snell's law, and correcting an underwater imaging error; secondly, acquiring a camera internal reference matrix by using a Zhang Zhengyou calibration method; then, a laser range finder is used for projecting laser to the calibration plate to form a light spot, the center pixel coordinate of the light spot is extracted through a gray gravity center method, the three-dimensional coordinate of the light spot is calculated in combination with laser ranging data, and the initial value of an external parameter matrix of the binocular camera is solved; and finally, introducing a Bayesian optimization algorithm, and optimizing the constraint equation by taking minimization of a three-dimensional coordinate calculation error as a target so as to obtain an exact solution of an external parameter matrix of the camera. Through organic combination of a deep learning technology and binocular stereo vision, the parameter calibration precision of the underwater binocular stereo vision camera is improved, a reliable technical guarantee is provided for subsequent underwater concrete structure defect quantification, and the fine monitoring requirement in a complex water environment is met.

The present application relates to the technical field of optical aspheric surface, especially refers to a kind of splicing aspheric surface characterization method based on CGH lens zero position compensation detection optical path, with the detection of aspheric surface as the guidance, based on zero position compensation detection principle, according to ray tracing method, Snell's law, diffraction principle and equal optical path principle, using the parameters required by the zero position compensation detection system of interferometer incident wave front as plane wave, compensator as single CGH lens and diffraction surface as binary optical surface 3 or binary optical surface 4 to characterize aspheric surface surface shape, and according to the aspheric surface type defined by the characterization method, it is called zero position splicing aspheric surface.According to the splicing aspheric surface characterization method, the measurement scheme can be determined in the design stage through the mathematical description of splicing aspheric surface, which avoids the influence of stray light and projection distortion of CGH detection, reduces the detection difficulty of splicing aspheric surface surface shape, and realizes the function of zero position splicing aspheric surface design.

The invention discloses an anti-interference directional antenna tracking method based on an acoustic beacon, and the method comprises the steps: 1, carrying out the multi-mode acoustic sensing, collecting the acoustic signals of a target region through an acoustic sensor array, and enabling the acoustic signals to comprise a coding signal transmitted by an active acoustic beacon and a feature noise signal generated by a target, establishing a sound wave-electromagnetic wave bimodal sensing network, and realizing data fusion by adopting extended Kalman filtering; 2, target identification and positioning: estimating the spatial position of a target object by adopting a corresponding positioning algorithm based on the type of the acoustic signal; step 3, adaptive beamforming is carried out, beamforming is carried out by adopting an improved generalized Snell law, and phase compensation provided by acoustic sensing is introduced; the invention relates to the technical field of sixth-generation mobile communication, and the technical scheme has excellent sensing performance and communication reliability in a complex environment, and is suitable for various 6G application scenes such as smart cities, security and protection monitoring, emergency rescue and the like.

The invention relates to the technical field of industrial control, and particularly discloses an intelligent visual measurement and control analysis system for a resin separation interface, which is characterized in that firstly, through image acquisition and HSV (hue, saturation, value) color space transformation, interface characteristics are accurately positioned in a complex illumination and window dirty environment by utilizing a hierarchical semantic segmentation technology; further, according to the scheme, a traditional linear perspective mapping model is abandoned, a light path refraction compensation mechanism based on the Snell law is constructed, interface pixel coordinates are converted into a sight incident angle, the nonlinear lateral displacement is calculated in combination with the window glass thickness and the refractive index, and therefore the real physical height for eliminating optical distortion is reconstructed. Based on the high-precision data, the system generates a control instruction through a PID strategy to drive a field valve, and precise closed-loop automatic control over the resin regeneration process is achieved.

The present invention proposes a method for inverting layered medium parameters using ground penetrating radar. This method can achieve accurate inversion of layered media with a small amount of computation and is applicable to multi-layer medium models. The present invention first implements the inversion of the first layer parameters using the traditional CMP method. Then, using this information, the propagation equations at different offsets are constructed based on the layered medium model. At the same time, Snell's law is used to represent the position of the refraction point at the layered interface, minimizing the error caused by the refraction effect at the layered location. The cost function for medium parameter inversion is established by combining the propagation equation with Snell's law. Then, in order to solve the problem of difficulty in deriving the cost function of multiple independent variables, an enumeration method is used to roughly optimize and obtain the initial value. A pattern search method is used for precise optimization and output of the ideal solution of the multi-layer parameters, achieving accurate inversion of the layered medium and providing accurate prior structure information for subsequent underground target imaging and identification detection.

A sound absorption device and method for an acousto-optic device that converts body waves into surface waves. The sound absorption device of the acousto-optic device mainly adopts a crystal similar to the acousto-optic crystal of the acousto-optic device, and the sound absorption crystal guides out and absorbs the sound energy in the acousto-optic crystal. The specific implementation method comprises the following steps: (1) calculating the sound velocity slowness curve of the acousto-optic interaction surface of the acousto-optic crystal and the sound absorption crystal; (2) using the Snell law of anisotropic crystals, calculating the phase velocity of the incident sound wave and the angle of the sound absorption surface when the reflected sound energy propagates along the interface at the sound absorption surface of the sound absorption crystal; (3) using the Snell law of anisotropic crystals, designing the angle of the connection surface between the sound absorption crystal and the acousto-optic crystal, so that the direction of the sound wave phase velocity in the sound absorption crystal is the design direction; (4) connecting the sound absorption crystal cut according to the design angle to the acousto-optic crystal, so that the ultrasonic energy is transmitted into the sound absorption crystal, and is converted from body waves to surface waves on the sound absorption surface and rapidly attenuated and absorbed, thereby improving the influence of the reflected sound field interference of the traditional sound absorption structure.

The invention relates to the technical field of hazardous article detection, and provides a small-size hazardous article terahertz wave band dielectric constant testing method and system, and the method comprises the steps: placing a to-be-tested material between two convex lenses, controlling a horn antenna of a spread spectrum module to emit an electromagnetic wave, and in any radiation angle, viewing the electromagnetic wave as a plane wave, acquiring an S parameter measured by the vector network analyzer, and performing conversion; obtaining the thickness of the to-be-measured material, and converting the thickness into equivalent thickness; obtaining an inversion dielectric constant through an inversion model; acquiring a radiation angle, an image distance and an object distance, converting an incident angle, and determining a conversion dielectric constant on the basis that the refraction angle and the incident angle meet the Snell law; the refraction angle enabling the difference between the inversion dielectric constant and the conversion dielectric constant to be minimum is searched, the dielectric constant under the corresponding radiation angle is obtained, the average dielectric constant is obtained through integration, and the method adapts to measurement of non-uniform samples and size-limited samples.

The invention discloses a three-dimensional reconstruction method for an underwater binocular system, and relates to the technical field of underwater optical three-dimensional measurement. The method comprises the following steps: receiving camera internal parameters and distortion coefficients calibrated by left and right cameras in the underwater binocular system in the air and relative external parameters between the two cameras; receiving plane equation parameters of a cabin mirror outer plane of the underwater binocular system in a left camera coordinate system and synchronous left and right image pairs of an object to be measured acquired by the underwater binocular system in an underwater environment, wherein the plane equation parameters comprise a normal vector n and a distance d from an original point to the plane; preprocessing the acquired left and right image pairs, and calculating a disparity map or a feature point corresponding relation by adopting a stereo matching algorithm; and a virtual image pre-calibration method is adopted to calibrate the initial error of the point cloud before and after correction, and the focusing parameter of the camera is adjusted. According to the method, cabin mirror interface parameters are accurately calibrated, strict light path tracking and the Snell law are combined, a physically accurate multi-refraction correction model is constructed, high-precision correction is carried out on the basis of traditional binocular reconstruction, and finally accurate three-dimensional coordinates of a real underwater object are obtained.

The invention provides an underwater sound tomography inversion precision and measurement distance improvement method and system based on a flexible sound energy reinforcing material, and the method comprises the steps: carrying out a simulation experiment in which parameters continuously change along with the position according to the Snell's law, and determining the sound velocity and thickness parameters of a to-be-prepared flexible sound energy reinforcing material through the relation between the refractive index and the sound velocity; the mass fraction of a matrix and a scatterer of the flexible sound energy reinforcing material is calculated, then the flexible sound energy reinforcing material is segmented based on parameter values and then prepared respectively, the flexible sound energy reinforcing material is obtained, finally, the temperature and the flow velocity are inversed through the transmission time difference of signals of the two hosts, and real-time temperature flow monitoring is achieved. The system can meet long-term real-time observation requirements of water flow of most estuaries and coastal areas, has the advantages of continuous monitoring, high energy utilization rate, high temporal-spatial resolution, wide coverage range, non-contact measurement, few required sites, high adaptability and the like, and provides technical support for hydrological monitoring engineering.

The invention belongs to the technical field of terahertz, and discloses a terahertz hologram rapid construction method based on a phase gradient metasurface and the phase gradient metasurface. According to the method, complex amplitude distribution is obtained according to target object information, phase distribution is calculated through fast Fourier transform, metasurface unit parameters are optimized through a genetic algorithm or a particle swarm optimization algorithm in combination with the generalized Snell law, and finally the terahertz hologram is generated through CS TMicrowave Studio electromagnetic simulation. The phase gradient metasurface is of a metal-medium composite structure, and the phase regulation and control range can be expanded through multi-layer design. The method has the advantages of rapidness, high efficiency, high-precision imaging, high universality, low-cost preparation, multifunctional application and the like, and can be widely applied to the fields of terahertz imaging, communication, security inspection, biomedical detection and the like.

an objective is to provide an optical element which has no discontinuous portion between adjacent lenses, and which suppresses a reduction of a light efficiency and also an occurrence of variability in light distribution due to diffusion, etc. An optical element capable of diffusing incident light to a predetermined diffusion range, and includes a transparent body including concavity-and-convexity on at least one surface. The diffusion range is defined as an internal side of a singular closed curved line on a predetermined plane. The concavity-and-convexity includes a plurality of crests and valleys without a periodicity. When it is defined that a wavelength of the light is λ, a refractive index of the transparent body is n1, and a refractive index of a medium around the transparent body is no, the concavity-and-convexity has no portion where a gradient of the concavity-and-convexity changes by 180 degrees within a range in which a width is λ / (n1−n0). A region of the concavity-and-convexity with the gradient causing the incident light to be emitted and outgo to a region outside the diffusion range by Snell's law is equal to or smaller than 5% of the entire region.

The invention provides a tracking method of a two-dimensional ray forward modeling seismic gather. The method comprises the steps of establishing mathematical physical models corresponding to incident and reflected rays; tracking from the emergent angle beta 0 of the surface ray to the underground, tracking downwards layer by layer according to the Snell's law of refraction, calculating the incident point of the incident ray and the incident stratum interface, and calculating the travel time of the incident ray in each layer; according to the reflection law, performing ray tracing on the earth surface layer by layer according to the Snell refraction law, calculating intersection points of reflected rays and each stratum interface, and calculating travel time of the reflected rays in each layer; tracking a normal ray and a pre-stack trace gather imaging ray of each layer corresponding to the common midpoint trace gather; and determining a common midpoint gather according to the earth surface incidence point, the stratum reflection point, the earth surface emergence point and the normal ray passing through the common midpoint, and determining a seismic pre-stack gather according to the imaging ray and the equal-offset incidence and reflection channels. A model which is more complex and closer to a real stratum is established, and deeper research is carried out on seismic wave speed forward modeling simulation.

The invention discloses an IMU (Inertial Measurement Unit) light path structure based on a metasurface, which is characterized in that a light beam generated by a laser 1 is divided into three mutually vertical light beams under the action of a beam splitting metasurface 3, and then is converted into circularly polarized light and linearly polarized light through a polarization conversion beam splitting metasurface 4, and the circularly polarized light and the linearly polarized light are respectively used for pumping and detecting a nuclear magnetic resonance gyroscope 6. The beam splitting metasurface 3 is composed of polarization-insensitive cylindrical nanorods, and incident light is split and generates corresponding deflection in combination with the generalized Snell law. The polarization conversion beam splitting metasurface 4 is composed of a polarization-sensitive rectangular nano-column and a polarization-insensitive cylindrical nano-column, the rectangular nano-column is used for converting linearly polarized light into circularly polarized light, and the cylindrical nano-column keeps the linear polarization characteristic and achieves beam splitting and direction adjustment. According to the invention, single laser configuration is adopted, efficient light field regulation and control are realized based on the metasurface, the problem that a traditional IMU light path system depends on a plurality of lasers is avoided, the system size, complexity and energy consumption are reduced, the stability and the integration degree are improved, and the system is suitable for high-precision inertial navigation application.

This invention discloses a metasurface and method for generating an orbital angular momentum vortex beam array. The metasurface includes a central region and N edge regions, which are symmetrically arranged along the central region. Each edge region comprises a unit structure with a gradually changing arrangement from the center to the edge. The edge regions deflect vertically incident linearly polarized light toward the central region. The deflection angle θ and the change in the unit structure size satisfy the generalized Snell's law. The method involves incident an expanded linearly polarized laser onto the metasurface, which, after transmission through the central region, is deflected and transformed into left-handed circularly polarized light (LCP) or right-handed circularly polarized light (RCP). The N edge regions, after transmission, generate a polarization angle θ toward the central region. The deflected beams interfere with the central beam to form a vortex beam array. The metasurface is composed of subwavelength structural units arranged periodically, with a size on the order of tens to hundreds of wavelengths, facilitating chip integration and producing a stable vortex array.

The application discloses an egg circle type scanning laser radar wave refraction correction error correction method, belongs to the technical field of airborne laser depth sounding, and is used for wave refraction correction of underwater terrain measurement of an airborne laser radar and comprises the following steps: filtering and processing sea surface point clouds by adopting a statistical outlier removal filtering method; extracting a sea surface slope normal vector corresponding to each point by adopting an optimized moving least square method; simplifying an egg circle type scanning laser radar measurement process to be carried out in a carrier coordinate system; constructing a refraction correction model by using Snell's law and a vector decomposition method; and obtaining corrected sea bottom point cloud coordinates. The application removes noise from sea surface point cloud data, fits the measured sea surface point cloud by using a moving least square method, adopts characteristic decomposition of a covariance matrix instead of polynomial fitting, and thus, the calculation is simple, polynomial fitting errors are avoided, the process is greatly simplified by using vector decomposition calculation, and there is only a single solution.

The invention discloses a geometric random underwater acoustic channel modeling method considering non-equal sound velocity. The method comprises the following steps: 1) constructing a shallow sea layered sound velocity profile; 2) multi-path propagation including a direct path, a sea surface reflection path and a seabed reflection path is considered; 3) calculating a propagation angle, a Doppler frequency shift, a propagation distance and a time delay parameter of a path between the receiving end and the transmitting end based on the layered sound velocity profile in combination with a geometric acoustic principle and a Snell law; and 4) establishing a channel impulse response and transmission function, calculating a time self-correlation function and a frequency correlation function at the same time, and performing analysis. According to the method, the non-equal sound velocity profile is introduced into the geometric random underwater acoustic channel model for the first time, the time-frequency fading characteristics of the channel under the equal sound velocity condition and the non-equal sound velocity condition are compared and analyzed, the physical authenticity and calculation precision of the model are improved, and reliable technical support is provided for design and performance evaluation of an underwater communication system.

The present invention discloses a free-form surface shaping device for controlling the light beam of a light source with a non-rotationally symmetric light intensity distribution. The present invention belongs to the field of non-imaging optical technology. The present invention sets the system optical path structure according to the lighting requirements, and flexibly controls the light source with a non-rotationally symmetric light intensity distribution by numerically trimming the free-form surface shape. The present invention mainly designs a free-form surface lens that meets the target lighting distribution based on Snell's law and the law of conservation of energy with the assistance of a computer. The present invention can control the non-rotationally symmetric light output distribution of the light source on the vertical axis and the inclined target surface, and can also simultaneously control the output light intensity and wavefront of the non-rotationally symmetric light source. The present invention can use only one free-form surface lens to shape the light output distribution of the light source into a target radiance distribution. The present invention has a simple structure; good shaping effect, high energy utilization rate; strong practicality, and a wide range of applications. The design of the present invention can ensure the continuity of the surface and is easy to process.

The application relates to the technical field of optical aspheric surfaces, in particular to an aspheric surface characterization method based on a zero-position compensation detection light path of a spherical single lens, which is oriented to aspheric surface detection, based on a zero-position compensation detection principle, according to a light ray tracing method, Snell's law and an equal optical path principle, and characterized by various parameters of a zero-position compensation detection system required by an interferometer incident wave front being a spherical wave and a compensator being a single lens, and according to an aspheric surface type defined by the characterization method, the aspheric surface type is called a zero-position aspheric surface. The aspheric surface characterization method can obtain detection-related data in the stage of designing an optical system, and can modulate and constrain characterization parameters of the zero-position aspheric surface according to imaging requirements, so as to balance factors such as system imaging quality, aspheric surface structure, compensator and detection light path rationality, and realize the function of aspheric surface design and detection.

Described herein are systems and methods for refraction correction of OCT images configured for intraoperative use, including: a deep-learning model configured to receive a plurality of OCT images; and an imaging device configured to generate the plurality OCT images during an intraoperative procedure; wherein the deep-learning model is configured to map, in real-time, the plurality of OCT images to a two-dimensional vector field over a spatial domain of the plurality of OCT images; wherein the mapping is configured for real-time correction of refraction errors on the plurality of OCT images by employing Snell's law to generate a plurality of refraction-corrected OCT images via the deep-learning model. Other examples are described including features of the deep-learning model uniquely configured for interoperative usage such as an OCT image processing speed of 20Hz-50Hz.

The invention relates to a nondestructive testing system and method for deep small crack defects of a wind power composite material blade. The method comprises the following steps: reasonably arranging a to-be-tested composite material wind power blade in a water tank and adjusting the position of an ultrasonic array probe; calibrating the ultrasonic imaging system according to related detection standards; ultrasonic imaging parameters are set in the main control computer, and remote focusing acoustic beam control is realized based on a time delay rule and a Snell law; and obtaining three-dimensional ultrasonic data in the blade in a multi-subaperture traversal scanning mode. Received signals are processed by combining a ray tracing model, time delay matrix construction and a non-linear coherence measurement algorithm, high-resolution imaging of deep tiny crack defects of the composite material blade is achieved, and noise interference caused by material anisotropy is effectively restrained. According to the method, nondestructive and high-resolution detection of the deep tiny cracks of the wind power composite material blade can be realized, and the method has important engineering application value and popularization significance.