12 results about "Diffraction model" patented technology

The invention relates to a convolutional neural network hologram generation method based on unsupervised learning, and belongs to the field of artificial intelligence technology and computer-generated holography. Comprising the following steps: incorporating a physical diffraction model into an unsupervised learning convolutional neural network, firstly inputting a target image into the SCLSK-Net network, outputting a predicted phase by a coding part, introducing space and channel reconstruction convolution into the coding part of the network, reducing redundancy calculation, promoting learning of representative features, and then transmitting to a decoding part; a large-selectivity nuclear network is introduced in a decoding part, a space acceptance field is dynamically adjusted, ranging environments of various objects in different scenes are simulated, then transmission of a physical diffraction model is realized, and learning parameters can be automatically updated by reversely transmitting loss to an initial coding part; and through an attention mechanism and space channel reconstruction convolution, generation of a high-quality rapid computer-generated hologram is realized.

The application discloses an optical element subsurface defect detection method and system based on phase contrast digital holography, and belongs to the field of precision measurement technology; the system adopts annular Bessel beam Kohler illumination, utilizes polarization modulation technology and a specially-made polarization contrast ring to realize synchronous four-step phase shift high-speed quantitative phase measurement in a U-shaped light path; the method acquires complex amplitude through a polarization camera, compensates for resolution loss by using a self-supervision super-resolution reconstruction algorithm fused with a physical model; full-field and local inverse diffraction reconstruction is carried out based on angular spectrum diffraction theory, high-precision depth positioning is realized based on the diffraction light complex amplitude distribution characteristics as a focusing criterion; three-dimensional information representation of defects is realized in combination with an optical field scattering and diffraction model and a machine learning algorithm; the application can realize high-sensitivity, high-signal-to-noise ratio, real-time in-situ quantitative detection and three-dimensional reconstruction of submicron defects without significantly increasing the cost.

The invention discloses a phase difference method wavefront detection method combined with image sensor noise suppression, and the method comprises the steps: building an ideal light spot image of an image surface and a defocus position based on a phase difference method phase recovery system diffraction model; calculating a noise suppression factor of each defocus position according to the average noisy image of each defocus position and the image sensor parameters, and applying the noise suppression factor to the corresponding average noisy image to obtain a corrected noisy image of each defocus position; and finally, substituting the ideal light spot image at each out-of-focus position and the corrected noise-containing image into a target function, optimizing through a nonlinear algorithm, repeatedly updating the Zernike coefficient and recalculating the ideal image, and finally obtaining a restored wavefront phase. According to the invention, the wavefront detection precision can be significantly improved.

The invention discloses a method and a system for generating and executing an anti-interference flight strategy of a C2 link of an unmanned aerial vehicle, and particularly relates to the technical field of unmanned aerial vehicle communication. The method comprises the following steps: acquiring urban building material parameters and unmanned aerial vehicle flight parameters; based on the parameters, combining a free space path loss model, a Rice fading model and a blade peak diffraction model to construct an urban environment channel model; injecting same-frequency Wi-Fi interference and building reflection interference signals to calculate a signal to interference plus noise ratio; based on the signal to interference plus noise ratio, calculating the bit error rate and evaluating the anti-interference performance, and generating an anti-interference optimization scheme including frequency band switching and flight height adjustment; and controlling the unmanned aerial vehicle to execute the strategy. Aiming at the problems of Wi-Fi co-frequency interference, building shielding, glass curtain wall multipath reflection and the like in a complex urban environment, frequency band self-adaptive switching and flight height optimization are realized through multi-model joint simulation and dynamic strategy generation, the bit error rate is reduced, the anti-interference capability is improved, and the method has the advantages of being simple in structure and convenient to operate. And the communication reliability and the flight safety of the unmanned aerial vehicle in a complex urban environment are effectively guaranteed.

The application provides a deep diffraction field velocity modeling method and device, electronic equipment and storage medium, relates to the deep resource exploration field, and the method comprises the following steps: obtaining diffraction wave separation data, constructing a common diffraction point multi-aperture angle gather through angle migration based on an edge diffraction model and a scatterer physical model, and capturing the diffraction response in the multi-aperture; according to the angle gather, a correction relationship between the diffraction point dip angle and the migration velocity is established; then, according to the correction relationship, for each common diffraction point multi-aperture angle gather, the diffraction field velocity spectrum of each diffraction point is calculated based on the local similarity and the mixed weight of the difference boot-strap; the diffraction wave velocity value of the focused signal is picked up through human-computer interaction; and finally, the model is constructed through interpolation. The application can effectively capture the weak energy of deep diffraction bodies, improve the focusing quality of the velocity spectrum, construct a refined velocity model, and provide support for imaging of deep dry hot rock and other unconventional reservoirs.

The invention provides a single-frame non-time-sequence color holographic display system and method. The system comprises a red, green and blue three-color laser, a beam expanding and collimating system, a first polarizer, a spatial light modulator, a beam splitter and a band-limited filtering plane which are sequentially arranged along a light path, the spatial light modulator is connected with a computer and is used for loading a single phase type hologram generated through an iterative optimization algorithm; according to the iterative optimization algorithm, a phase hologram is generated based on a Fresnel diffraction model and a stochastic gradient descent method, laser emitted by a red-green-blue three-color laser is irradiated to a spatial light modulator through a beam splitter, modulated by the hologram in the spatial light modulator and then transmitted to a band-limited filtering plane, and a single-frame non-time-sequence color holographic image is reproduced. According to the invention, the wavefront information of the color object can be completely recorded and reproduced only by using one hologram without depending on high-refresh-rate equipment or complex synchronous control, so that the light path structure is effectively simplified, the cost is reduced, and the reproduction quality and stability of the image are improved at the same time.

A focus adjustment method for acquiring an image of a surface of interest of a sample by a holographic imager includes the steps of:placing the sample including at least one reference object having a known shape and described by characterising parameters having at least position parametersacquiring an image and determining the position of the reference object with respect to the acquisition plane, by applying a light diffraction model involving the spatial parameters of the reference object estimated by approximating the appearance of the reference object in the holographic image acquired, anddetermining the position of the surface of interest with respect to the acquisition plane from a position of the reference object and focus adjustment of the image acquisition.

Measuring overlay using a microscope based sensor with dark-field fringe-based imaging is described. The signal from the sensor is an intensity modulated fringe pattern (e.g., an interference pattern) as generated through the cross-interference of two diffraction orders from the metrology target. A metrology target comprises a first metrology mark in a first layer of a patterned substrate (e.g., a semiconductor wafer) and a second metrology mark in a second layer. Parameters associated with the fringes of the intensity modulated fringe pattern are determined, and used to make robust overlay determinations that are compensated for in plane vibrations of the patterned substrate. Advantageously, overlay values for metrology targets are determined based on the parameters, using a multi-parameter optimization based inference of the overlay values for multiple metrology targets together with the parameters related to the diffraction model and the sensor disturbances.

The invention discloses a resolution improvement limit derivation method. The method comprises the following steps: converting an echo signal into an echo signal matrix expression under a geometric diffraction model; echo vector probability distribution is obtained under the condition that preset noise is Gaussian complex noise, and an echo likelihood function is obtained according to the echo vector probability distribution; calculating a Fisher information matrix of the scattering center parameter; obtaining CRLB of the scattering center parameters according to the Fisher information matrix of the scattering center parameters; obtaining the minimum distance between the two scattering centers according to the pole phase difference of the two scattering centers under the pole model; obtaining the phase difference of two poles in the first sub-band and the phase difference of two poles in the double sub-bands according to the minimum distance between the two scattering centers; and obtaining a resolution improvement limit according to the phase difference minimum value of the two poles in the first sub-band and the phase difference minimum value of the two poles in the double sub-bands. The invention solves the problem that the existing resolution improvement limit is only suitable for a point scattering center and has a narrow application range.

The application discloses a double-sided achromatic superlens based on phase load balancing and a design method, and belongs to the technical field of micro-nano optics and computational imaging. The superlens comprises a transparent low-refractive substrate, a first structure layer located on the incident surface of the substrate and a second structure layer located on the emitting surface of the substrate; the first structure layer is a non-periodic phase type Fresnel zone plate, which is used for providing a basic focusing phase and pre-bending incident parallel light to the inside of the substrate; the second structure layer is an isotropic cylindrical nano column arranged in a square lattice, which is used for providing a residual focusing phase and a wide-band chromatic aberration compensation phase. Through the double-sided phase distribution balancing logic, the light deflection pressure is shared together, combined with the full-path scalar diffraction model, super-atom response calculation and end-to-end deep learning optimization, the bottleneck of low-refractive material in high-NA achromatic application is completely solved, and the micro-nano processing technology of large area and low cost is compatible.

The application discloses a design method of dihedral angle error of a single corner reflector, and the method comprises the following steps: calculating the variation range of a speed difference angle according to the orbital elements of a ranging target; constructing a far-field diffraction model based on the dihedral angle error compensation speed difference effect; inputting the parameters of the corner reflector and the ranging laser and the variation range of the speed difference angle into the far-field diffraction model as input conditions; performing far-field diffraction simulation on the corner reflector with dihedral angle error in the Fraunhofer formula in the far-field diffraction model to obtain corresponding far-field energy distribution; and calculating the optimal dihedral angle error of the corner reflector according to the far-field energy distribution. The design method of the dihedral angle error has strong universality and can be applied to various laser ranging scenes.

The invention relates to a hologram intelligent compression and reconstruction system and method, and belongs to the field of hologram processing. Comprising the step of realizing high-efficiency compression and high-quality reconstruction of holographic data through three core technologies of dynamic range segmentation, perception weight optimization and adaptive quantization when a CCD records a hologram. The method comprises the following steps: firstly, segmenting a hologram into a high dynamic range (HDR) region and a low dynamic range (LDR) region by adopting a local feature analysis technology and combining a dynamic threshold value; secondly, enhancing high-frequency information retention by using a frequency sensitive weight; and iteratively optimizing parameters through a code rate control module, implementing nonlinear quantization on an HDR region, and implementing linear quantization on an LDR region. In the reconstruction stage, a Fresnel diffraction model is adopted for physical reduction, and a holographic reproductive image is obtained. According to the method, a high compression ratio is achieved in airspace compression, and meanwhile high quality of a reconstructed image of the compressed hologram is guaranteed.