Optical Memory and Neural Networks最新文献

In this work, we investigated tight focusing characteristics of beams, which do not contain longitudinal component of intensity. The investigated beams have azimuthal or sector-azimuthal polarization and could contain vortex phase. It was numerically shown that beams with azimuthal and sector azimuthal polarization do not contain longitudinal component of intensity. Moreover, the helical phase added to the beams does not add longitudinal component to the electric field; however, it could be used for manipulation with longitudinal component of spin angular momentum in the tight focus. The possibility of generation of investigated beams was demonstrated using vector waveplates and spatial light modulator.

This article proposes an approach to the analysis of high-resolution hyperspectral images in the applied problem of analyzing the state of river waters. This method allows you to detect blooming or contamination of water by foreign substances. High-resolution hyperspectral images were obtained using a hyperspectrometer mounted on a small unmanned aerial vehicle. The difference between the spectra of river areas with different intensity of algal blooms is demonstrated. Samples of river water were taken, chemical analysis was carried out, which confirmed the different content of magnesium and calcium in all samples, corresponding to the intensity of algal blooms in the water. The effectiveness of using machine learning algorithms and the construction of index images for the classification of water areas with different intensity of algal blooms is shown.

An adaptive method for wavefront aberrations compensating has been developed based on the use of a spatial light modulator, the phase function of which is matched to a set of Zernike functions. It is proposed to use the second central moment of intensity of the focal image as a functional. A study of the second central moment was carried out for both individual wavefront aberrations and their superposition. It is shown that achieving the reference value of the second moment can serve as a sign of sufficient compensation for aberration.

The paper considers the squared Laguerre-Gaussian beams. Using the Fresnel integral, numerical modeling of the propagation of such beams in turbulent media is performed. The topological charges of the resulting fields are calculated. The behavior of squared Laguerre-Gaussian beams is compared with conventional Laguerre-Gaussian modes. Analysis of the obtained results showed that even for strong turbulence, the average deviation of the topological charge does not exceed 5%.

In this paper, we consider a method for estimating camera motion parameters from images acquired from this camera, which is based on the use of vector coplanarity estimation. It has been previously shown that the proposed approach can be effectively applied to three-dimensional scenes invariant to their depth. However, due to the criterion used, it is difficult to utilize the RANSAC method to ensure the robustness of the developed method. In this paper, an approach based on the minimum covariance determinant estimation method is proposed. The proposed approach allows us to select the most consistent observations and make an estimation based on these observations. An experimental study of the proposed approach on synthetic data has been carried out. It is shown that the proposed algorithm can provide a significant increase in the reliability of motion parameters determination even in conditions of a small number of corresponding points

The original features of low-temperature off-electrode plasma of a high-voltage gas discharge, the basis of its occurrence and self-sustainment are demonstrated. As part of a new approach to the formation of wide-format (diameter up to 200 mm) directed flows of low-temperature off-electrode plasma and a class of corresponding gas-discharge devices (free from the disadvantages characteristic of modern domestic and foreign analogues), complex electrode systems are considered. They make it possible to generate directed flows of such plasma at a discharge current in hundreds and thousands of milliamps and electrode voltages of 0.3–1 kV. Based on experimental testing of these electrode systems, methods for cleaning the surface, increasing the adhesive strength of thin metal films and spatially selective etching of semiconductor and dielectric materials in off-electrode plasma for micro- and nano-sized structuring of their surface have been proposed.

The aim of the work is differential diagnosis of retinal edema, study of deep learning methods and their application to image analysis. The application of convolutional neural networks to the task of semantic segmentation of retinal layers was investigated and its efficiency in selecting two selected layers (pigment epithelium and retina) was proved. A disease classifier based on intelligent analysis of the layers extracted by the neural network was implemented. A proof of its applicability for differential diagnosis of retinal edema was presented. The accuracy of disease prediction amounted to 90%.

The dynamics of the optical field in a resonator with cubic nonlinearity, delayed feedback and external injection is investigated. It is shown that the formation of square optical waves is possible in such a system. The mechanism of formation of such waves is found. Possible solutions in the form of square optical waves are numerically investigated. A diagram illustrating possible solutions is constructed.

This article is devoted to a new direction of modern singular optics—Erf-Gaussian (EG) beams that carry a fractional topological charge. It is shown that Erf-Gaussian beams were generated using an axicon and an anisotropic crystal, and the polarization characteristics of these beams with a fractional topological charge in the vicinity of the beam axis were experimentally studied. Theoretical calculations were confirmed and it was shown that Erf-Gaussian beams introduce changes into the original picture of the polarization distribution, and that the central spiral polarization umbilical splits into two polarization features of the “lemon” type. The method described in the article for generating and analyzing polarization singularity in Erf-Gaussian beams based on a fractional topological charge can be used in optical profilometry to analyze the polarization and phase properties of materials and surface roughness.

In this work, using the Richards-Wolf formalism, we assume the tight focusing of optical vortices with hybrid polarization, which combines the properties of azimuthal and circular polarizations. It is shown that these beams have a number of unique properties the intensity in such beams rotates with length from the focal spot, and the longitudinal component of the spin angular momentum has an asymmetric appearance.