Computer Optics

173-183

Authors: L.L. Doskolovich, A.A. Mingazov, E.V. Byzov, D.A. Bykov, E.A. Bezus

We develop a method for calculating the eikonal function (or the phase function) of the light field, ensuring the formation of a prescribed irradiance distribution in the geometrical optics approximation. In the proposed method, the problem being solved is formulated in a semi-discrete form as a problem of the maximization of a concave function. For finding the solution to the latter problem, a gradient method is used, with analytical expressions obtained for the gradient. Using the developed method, we calculate an eikonal function that provides the formation of a “discontinuous” hexagram-shaped irradiance distribution. We demonstrate that the use of the solution obtained in the framework of the geometrical optics as an initial approximation in iterative Fourier transform algorithms allows one to calculate diffractive optical elements having a quasi-regular microrelief.

189-195

Authors: A.G. Nalimov, V.V. Kotlyar

In this work, using the Rayleigh-Sommerfeld integral and the Berry formula, the topological charge (TC) of a Gaussian optical vortex with an initial fractional TC is calculated. It is shown that for different fractional parts of the TС, the beam contains a different number of screw dislocations, which determine the TС of the entire beam. With a small fractional part of the TС, the beam consists of the main optical vortex centered on the optical axis with the TС equal to the nearest integer (let be n), and two edge dislocations located on the vertical axis (above and below the center). With an increase in the fractional part of the initial TC, a "dipole" is formed from the upper edge dislocation, consisting of two vortices with TC+1 and –1. With a further increase in the fractional part, the additional vortex with TC+1 is displaced to the center of the beam, and the vortex with TC–1 is displaced to the periphery. With a further increase in the fractional part of the TC, another "dipole" is formed from the lower edge dislocation, in which, on the contrary, the vortex with TC–1 is displaced to the optical axis (to the center of the beam), and the vortex with TC+1 is displaced to the beam periphery. When the fractional part of the TC becomes equal to 1/2, the "lower" vortex with TC–1, which was displaced to the center of the beam, begins to shift to the periphery, and the "upper" vortex with TC+1 moves closer and closer to the center of the beam and merges with the main vortex when the fractional part approaches 1. Such dynamics of additional vortices with upper TC+1 and lower TC–1 determine the whole TC the beam have (n or n+1) for different values of the fractional part from the segment [n, n+1].

204-213

Authors: S.A. Shoydin, A.L. Pazoev, A.F. Smyk, A.V. Shurygin

The manuscript presents experimental results on the recording and restoration of 3D holographic frames suitable for transmitting 3D holographic images with the frame rate required for TV images and the resolution of the Full HD standard and higher. The method is based on the previously proposed technology for recording and transmitting a depth map and surface texture of the holographic object over the communication channel and digital synthesis of the hologram at the receiving end of the communication channel. The obtained result reduces the frequency band required for the transmission of 3D holographic information, similar to SSB technology, since the carrier spatial frequency of the hologram in this method is not transmitted through the communication channel, but is synthesized in the hologram already at its receiving end. Experimental results of hologram synthesis at the receiving end of the communication channel in DotMatrix technology are presented. The method considered in this manuscript is convenient for multiplexing 3D images, transferring them from one part of the electromagnetic spectrum to another, as well as for creating hyperspectral images. The work implements the technology of a holographic phototelegraph, which, when using high-speed dynamic holographic monitors, can solve the problems of creating 3D TV and augmented reality.

219-223

Authors: G.I. Greisukh, I.A. Levin, S.V. Kazin

Requirements for the optical tract of a capsule medical endoscopic system with a frontal location of the object under research are summarized. It is shown that the optical layout of a microlens built from easy-to-fabricate modern plastics not only allows satisfying generalized requirements, but also opens up the possibility of obtaining a significantly higher-quality image in simple-design lenses compared with well-known analogs. This is confirmed by the presented results of calculating a microlens with a relative aperture of 1: 2.4 and an angular field of view of 2*(omega)=170°, which forms an image with a diameter of 2.7 mm with a resolution of at least 188 mm-1, and a contrast of 0.5.

232-238

Authors: D.A. Marakasov, A.L. Afanasiev, V.A. Banakh, A.P. Rostov, V.V. Kuskov

The article presents an optical method for assessing the transverse wind, based on the analysis of turbulent distortions of the image of a diffuse target illuminated by a laser beam. The proposed correlation algorithm for processing video images allows one to assess in real time the crosswind speed using one receiving lens when the target is illuminated in the visible or infrared range. An experimental check of the method on the atmospheric path has been carried out. The optical estimates of the integral wind are compared with the data of independent local measurements of six ultrasonic anemometers located along the sensing path.

246-251

Authors: K.A. Halavataya, K.V. Kozadaev, V.S. Sadau

Videoendoscopic and tomographic research are the two leading medical imaging solutions for detecting, classifying and characterizing a wide array of pathologies and conditions. However, source information from these types of research is very different, making it hard to cross-correlate them. The paper proposes a novel algorithm for combining results of based on 3D surface reconstruction methods. This approach allows to align separate parts of two input 3D surfaces: surface obtained by applying bundle adjustment-based 3D surface reconstruction algorithm to the endoscopic video sequence, and surface reconstructed directly from separate tomographic cross-section slice projections with regular density. Proposed alignment method is based on using local feature extractor and descriptor algorithms by applying them to the source surface normal maps. This alignment allows both surfaces to be equalized and normalized relative to each other. Results show that such an adjustment allows to reduce noise, correct reconstruction artifacts and errors, increase representative quality of the resulting model and establish correctness of the reconstruction for hyperparameter tuning.

271-279

Authors: T.J. Liang, W.G. Pan, H. Bao, F. Pan

In recent years, vision-based object detection has made great progress across different fields. For instance, in the field of automobile manufacturing, welding detection is a key step of weld inspection in wheel production. The automatic detection and positioning of welded parts on wheels can improve the efficiency of wheel hub production. At present, there are few deep learning based methods to detect vehicle wheel welds. In this paper, a method based on YOLO v4 algorithm is proposed to detect vehicle wheel welds. The main contributions of the proposed method are the use of k-means to optimize anchor box size, a Distance-IoU loss to optimize the loss function of YOLO v4, and non-maximum suppression using Distance-IoU to eliminate redundant candidate bounding boxes. These steps improve detection accuracy. The experiments show that the improved methods can achieve high accuracy in vehicle wheel weld detection (4.92 % points higher than the baseline model with respect to AP75 and 2.75 % points higher with respect to AP50). We also evaluated the proposed method on the public KITTI dataset. The detection results show the improved method’s effectiveness.

298-307

Authors: W. Soewondo, S.O. Haji, M. Eftekharian, H.A. Marhoon, A.E. Dorofeev, A.T. Jalil, M.A. Jawad, A.H. Jabbar

Breast cancer is one of the most dreaded diseases that affects women worldwide and has led to many deaths. Early detection of breast masses prolongs life expectancy in women and hence the development of an automated system for breast masses supports radiologists for accurate diagnosis. In fact, providing an optimal approach with the highest speed and more accuracy is an approach provided by computer-aided design techniques to determine the exact area of breast tumors to use a decision support management system as an assistant to physicians. This study proposes an optimal approach to noise reduction in mammographic images and to identify salt and pepper, Gaussian, Poisson and impact noises to determine the exact mass detection operation after these noise reduction. It therefore offers a method for noise reduction operations called Quantum Inverse MFT Filtering and a method for precision mass segmentation called the Optimal Social Spider Algorithm (SSA) in mammographic images. The hybrid approach called QIMFT-SSA is evaluated in terms of criteria compared to previous methods such as peak Signal-to-Noise Ratio (PSNR) and Mean-Squared Error (MSE) in noise reduction and accuracy of detection for mass area recognition. The proposed method presents more performance of noise reduction and segmentation in comparison to state-of-arts methods. supported the work.

317-325

Authors: А.A. Mikhaylichenko, Y.М. Demyanenko

In this paper, we investigate the effect of squeeze-and-excitation blocks on improving the classification quality of osteoarthritis using convolutional neural networks of the ResNet and DenseNet families. We show that the use of these blocks improves the quality of osteoarthritis classification according to the Kellgren-Lawrence scale by 1–3 % without a significant modifi-cation of the model structure. We also demonstrate that combining the 0 and 1 classes of the Kellgren-Lawrence scale into one class allows one to increase the accuracy of osteoarthritis grading by 12.74 %, without losing significant information about the disease. The best final ac-curacy attained was 84.66 % when using an ensemble of three convolutional networks with the DenseNet-121 architecture using squeeze-and-excitation blocks, which significantly exceeds the performance of the existing state-of-the-art. The obtained results can be used both for a prelimi-nary automatic diagnosis and as an auxiliary tool.

335-344

Authors: O.A. Basova, S.A. Gladilin, A.S. Grigoryev, D.P. Nikolaev

In this paper, we examine the applicability limits of different methods of compensation of the individual properties of self-emitting displays with significant non-uniformity of chromaticity and maximum brightness. The aim of the compensation is to minimize the perceived image non-uniformity. Compensation of the displayed image non-uniformity is based on minimizing the perceived distance between the target (ideally displayed) and the simulated image displayed by the calibrated screen. The S-CIELAB model of the human visual system properties is used to estimate the perceived distance between two images. In this work, we compare the efficiency of the channel-wise and linear (with channel mixing) compensation models depending on the models of variation in the characteristics of display elements (subpixels). It was found that even for a display with uniform chromatic subpixels characteristics, the linear model with channel mixing is superior in terms of compensation accuracy.

5-15

Authors: A.V. Volyar, E.G. Abramochkin, Y.E. Akimova, M.V. Bretsko

Using an asymptotic approach and an experiment supported by computer simulation, we analyzed processes of restoring structural stability and transitions to new stable states of spiral vortex beams subject to perturbations by curly apertures. Using a tetragonal beam as an example, we considered three perturbation scenarios: 1) asymmetric perturbation, when an opaque screen covers the caustic only on one side of the square, 2) symmetric perturbation, when the curly aperture covers the entire beam except for a narrow caustic region, and 3) symmetric perturbation, when the curly aperture screens only a narrow region of the caustic without affecting the rest of the beam. At the same time, the asymptotic calculation was carried out for all types of polygonal beams. It was shown that if the curly aperture did not destroy the caustic region of the spiral beam, it was able to self-heal in the far diffraction zone. If the perturbation even locally destroyed a part of the caustics, then the perturbed beam passed into a new stable state through chains of creation and annihilation of optical vortices (dislocation reactions).

22-29

Authors: E.G. Anufriyev

Nowadays, due to the lack of available radio frequency spectrum, there is a need for the development of technologies that would make it possible to use this spectrum more efficiently. One such technology involves the use of radio waves with orbital angular momentum (OAM). This paper proposes a new quantitative method for determining the number of single states of a beam carrying OAM based on an analysis of the S21 system parameters. This allows the receiver to be tuned to receive beams with a specific OAM state. The radio waves carrying OAM have a frequency of 80 GHz. In this work, a pyramidal horn was used as a transmitting antenna, with a spiral phase plate used to twist the emitted radio wave. An array of receiving antennas was in the form of dipoles. Limitations of this method were investigated. This work is a computer experiment.

39-47

Authors: S.A. Degtyarev, D.A. Savelyev

This article proposes a new type of subwavelength axicons for creating and focusing second-order vector cylindrical beams. It is also shown that using the proposed subwavelength axicons, it is possible to create focal spots with an energy backflow. The Comsol Multiphysics software is used to simulate the operation of subwavelength axicons with different twist angles. The dependence of the obtained intensity distributions on the angle of twist of the axicon spiral is investigated.

56-64

Authors: A.A. Rastorguev, S.I. Kharitonov, N.L. Kazanskiy

We propose a method for calculating the point scattering function (PSF) of an Offner imaging hyperspectrometer with a diffraction grating in the approximation of scalar diffraction theory. The method consistently takes into account limitations and diffraction of a light beam by elements of the hyperspectrometer system in accordance with the physics of image formation. The PSF of the Offner imaging hyperspectrometer is numerically simulated at various beam parameters and wavelengths. The simulation results are verified using analytical relationships, a geometrical optics approach, as well as a comparison with the related works of other researchers.

71-82

Authors: P.V. Karnaushkin, M.S. Sklyarenko

The work is devoted to a technique of pre-alignment of a lensed fiber and a channel waveguide of a photonic integrated circuit using computer vision methods. The design and main units of a machine vision system with illumination of the adjusted objects in reflected light are described. The technique includes detection of the spatial position of the end face of the photonic integrated circuit, fixed at an angle of 90 ± 1° to the horizontal axis of the frame, detection of the coordinates of the end face of the lensed fiber, and the subsequent correction of the position of the lensed fiber using a manipulator system. We propose a method of searching and selecting a single line corresponding to the end face of a photonic integrated circuit using a Hough transform; methods for grouping discontinuous contours of the lensed fiber and true contour determination. These methods are based on a priori knowledge of the lens geometry. Also, we describe options for suppressing noise and overcoming various defects in images. It has been shown experimentally that the error of angle determination of a lensed fiber depends on the distance between the lens and the end face of the photonic integrated circuit. The presented technique makes it possible to determine the longitudinal and angular displacements between the fiber lens and the end face of the photonic integrated circuit with errors less than 4 μm and 0.05°, respectively.

90-96

Authors: I.V. Bychkov, G.M. Ruzhnikov, R.K. Fedorov, A.K. Popova, Y.V. Avramenko

The paper considers a problem of classifying Sentinel-2 multispectral satellite images for environmental monitoring of the Baikal Natural Territory (BNT). The specificity of the BNT required the creation of a new set of 12 classes, which takes into account current problems. The set was formed in such a way that the areas corresponding to these classes completely covered the BNT. A training dataset was formed using a web interface based on Sentinel-2 satellite images. The classification of satellite images was carried out using Random Forest algorithms and the ResNet50 neural network. The accuracy of the calculations showed that the classification results can be used to solve actual problems of the Baikal natural territory, in particular, to analyze changes in the forestland, assess the impact of climate change on the landscape, analyze the dynamics of development activities, create farmland inventory, etc.

103-112

Authors: A.Y. Bavrina, V.A. Fedoseev

The article proposes a new semi-fragile watermarking system with the ability of tamper localization and recovery after distortions, adapted for the HGI image compression method. The system uses a hierarchical image structure when embedding and replaces the stage of post-interpolation residuals quantization with a special quantizer based on quantization index modulation. As a result, the protected image becomes resistant to HGI compression with an adjustable quality parameter. The proposed watermarking system allows an image to be restored after distortions with an acceptable quality. In this case, the authentication part and the recovery part operate at different hierarchical levels. The developed watermark system, compatible with the HGI compression method, may be used to protect remote sensing images and medical images from malicious distortion.

121-129

Authors: S.V. Sai

The article proposes a method for assessing photorealistic image quality based on a comparison of the detail coefficients in the original and distorted images. An algorithm for identifying fine structures of the original image uses operations of active pixels segmentation, which include point objects, thin lines and texture fragments. The number of active pixels is estimated by the value of a fine detail factor (FDF), which is determined by the ratio of active pixels to the total number of image pixels. The same algorithm is used to calculate the FDF of the distorted image and, further, the image quality deterioration is estimated by comparing the obtained values. Special features of the method include the fact that the identification of small structures and the segmentation of active pixels are performed in the normalized system N-CIELAB. The algorithm also takes into account the influence of false microstructures on the results of the restored image estimating. Features of the construction of neural networks SRCNN in the tasks of a qualitative increase in the image resolution with the restoration of fine structures are considered. Results of the analysis of the quality of enlarged images by the traditional metrics PSNR and SSIM, as well as by the proposed method are also presented.

139-159

Authors: N.A. Andriyanov, V.E. Dementiev, A.G. Tashlinskiy

The relevance of the tasks of detecting and recognizing objects in images and their sequences has only increased over the years. Over the past few decades, a huge number of approaches and methods for detecting both anomalies, that is, image areas whose characteristics differ from the predicted ones, and objects of interest, about the properties of which there is a priori information, up to the library of standards, have been proposed. In this work, an attempt is made to systematically analyze trends in the development of approaches and detection methods, reasons behind these developments, as well as metrics designed to assess the quality and reliability of object detection. Detection techniques based on mathematical models of images are considered. At the same time, special attention is paid to the approaches based on models of random fields and likelihood ratios. The development of convolutional neural networks intended for solving the recognition problems is analyzed, including a number of pre-trained architectures that provide high efficiency in solving this problem. Rather than using mathematical models, such architectures are trained using libraries of real images. Among the characteristics of the detection quality assessment, probabilities of errors of the first and second kind, precision and recall of detection, intersection by union, and interpolated average precision are considered. The paper also presents typical tests that are used to compare various neural network algorithms.

789-799

Authors: A.V. Volyar, Ya.E. Akimova

We investigated conditions for the violation of the structural stability of a spiral beam subject to sector perturbations. Based on the method of computer simulation and measurement of mode spectra, we have shown that a spiral vortex beam has a characteristic caustic surface, the intersection of which sharply changes the shape of the Poynting vector streamlines and the total topological charge of the beam. Sector beam perturbation does not almost change the streamline structure up to scale and rotation. We found that perturbation of the beam causes a change in the direction of circulation of streamlines in the region of perturbation, which is caused by the appearance of vortices with negative topological charges. Their contribution to the total energy flow is fractions of a percent. However, such perturbations do not cause changing the OAM in the beam, despite an increase in the number of vortex modes. Nevertheless, the perturbed beam remains only conditionally structurally stable due to the presence of a small fraction of optical currents with opposite circulations.

809-817

Authors: A.A. Kovalev, V.V. Kotlyar, D.S. Kalinkina, A.G. Nalimov

We discuss paraxial light beams composed of decentered Gaussian beams, with their phase selected in a special way so that their superposition is invariant as it propagates in free space, retaining its cross-section shape. By solving a system of five nonlinear equations, a superposition is constructed that forms an invariant off-axis elliptic Gaussian beam. An expression is obtained for the orbital angular momentum of this beam. It is shown that it consists of two components. The first of them is equal to the moment relative to the center of the beam and increases with increasing ellipticity. The second one quadratically depends on the distance from the center of mass to the optical axis (an analogue of Steiner's theorem). It is shown that the orientation of the ellipse in the transverse plane does not affect the normalized orbital angular momentum.

828-838

Authors: M.S. Gubaev, S.A. Degtyarev, Y.S. Strelkov, S.G. Volotovskiy, N.A. Ivliev, S.N. Khonina

We propose to use a refractive conical axicon for generating azimutally polarized beams. We investigate polarization states of optical rays passing through an interface between optical media, and also polarization transformation with a refractive axicon. We develop a software for raytracing which correctly processes polarization states of the rays and visualizes ellipses of polarization. The polarization state is described in the Jones notation and based on the energy conservation law. We derive and implement formulas for calculating the Jones vector in different bases, as well as trans-ferring the Jones vector from one basis to another. Algorithms for displaying polarization ellipses on one plane for beams that are not plane-parallel have been developed. Ray paths in a three-dimensional axicon are calculated and shown with due regard for polarization.

848-852

Authors: Y.E. Geints, O.V. Minin, I.V. Minin

We propose and discuss main properties of a new concept of an all-optical dielectric two-channel wavelength-selective switch based on the photonic hook effect. A prototype of such a de-vice based on dielectric microstructures with broken symmetry of both geometric shape and optical properties without the use of micromechanical devices or nonlinear materials is considered. Due to the unique property of the photonic hook to change its curvature depending on the wavelength of illuminating light, this switch is a promising candidate for the implementation of optical switching in modern optoelectronics and miniature devices "on a chip". Based on numerical FDTD simulations, it is shown that the optical isolation of switched channels for a switch with linear dimensions of about (6 * "lambda")3 based on a Janus particle can reach about 18-20 dB in the wavelength range of 1.5 – 1.9 microns.

860-864

Authors: M.S. Komlenok, O.S. Kudryavtsev, D.G. Pasternak, I.I. Vlasov, V.I. Konov

A possibility of laser printing of single diamond nanoparticles with luminescent SiV centers is demonstrated. To provide the transfer, a target consisting of a transparent sapphire plate and an absorbing thin titanium film (600 nm thick) coated with nanoparticles was irradiated with a KrF excimer laser ("lambda"=248 nm, "tau"=20 ns). Optimal values of the laser fluence have been determined and a technique for applying labels for the targeted transfer of nanoparticles has been developed. Luminescence mapping of the donor and the receiving substrates confirmed the transfer of diamond nanoparticles with SiV centers.

873-878

Authors: R.A. Paringer, A.V. Mukhin, A.V. Kupriyanov

The paper is about the development of an approach which able to create rules for distinguish-ing between specified objects of hyperspectral data using a small number of observations. Such an approach would contribute to the development of methods and algorithms for the operational analysis of hyperspectral data. These methods can be used for hyperspectral data preprocessing and labeling. Implementation of the proposed approach are using a technology that harnesses both discriminative criteria and the general formulas of spectral indexes. In implementing the proposed technology, the index was defined with normalized difference formula. The Informativeness was estimated using separability criteria of discriminative analysis. The results show that the implemented algorithm can recognize areas of hyperspectral data with different vegetation. The index formed by the algorithm is similar to Normalized Difference Vegetation Index (NDVI). The proposed technology is the generalization of the approach of forming recognition rules using a small number of features. It has been shown that technology can form informative indexes in specified tasks of hyperspectral data analysis.

887-896

Authors: N. Firsov, V. Podlipnov, N. Ivliev, P. Nikolaev, S. Mashkov, P. Ishkin, R. Skidanov, A. Nikonorov

In this paper, we propose an approach to the classification of high-resolution hyperspectral images in the applied problem of identification of vegetation types. A modified spectral-spatial convolutional neural network with compensation for illumination variations is used as a classifier. For generating a training dataset, an algorithm based on an adaptive vegetation index is proposed. The effectiveness of the proposed approach is shown on the basis of survey data of agricultural lands obtained from a compact hyperspectral camera developed in-house.

907-916

Authors: I.A. Kanaeva, Yu.A. Ivanova, V.G. Spitsyn

We discuss a range of problems relating to road pavement defects detection and modern approaches to their solution. The presented comparison of publicly available datasets allows one to make a conclusion that the problem of segmentation of road pavement defects in driver wide-view road images is difficult and poorly investigated. To solve this problem, we have developed algorithms for generating a synthetic dataset for cracks and potholes distress based on computer graphics methods and deep convolutional generative adversarial networks. A comparison of the accuracy of road distress segmentation was performed by training a fully convolutional neural network U-Net on real and combined datasets.

926-933

Authors: I.V. Zenkov, A.V. Lapko, V.A. Lapko, E.V. Kiryushina, V.N. Vokin, A.V. Bakhtina

We study in which way a priori information on the independence of random variables affects the approximation accuracy of a nonparametric estimate of the Rosenblatt–Parzen probability density. A new technique for generating sets of independent components of a multidimensional random variable is proposed. The methodology is based on testing the hypotheses of the independence of combinations of the multidimensional random variable components using a two-alternative nonparametric kernel algorithm for pattern recognition corresponding to the maximum likelihood criterion. Classes correspond to the domains of definition of the probability densities of sets of independent and dependent components of the multidimensional random variable. Nonparametric statistics of the kernel type are used to estimate the probability densities. The choice of the bandwidths of the kernel estimates of the probability densities is made from the condition of the minimum root-mean-square criterion. The sequential procedure for generating a set of independent components begins with the analysis of paired combinations of components of a multidimensional random variable. For each pair of components, the probability of an error in recognizing classes corresponding to the assumptions of independence and dependence of the considered components is estimated. A pair of components with the maximum difference between these errors is determined. If the errors obtained do not differ significantly, then there are no independent components in the considered multivariate random variable. If there is a significant difference in the probability estimates of class recognition errors, a pair of independent components is established. These components are included in a three-component set of a multidimensional random variable. The analysis of their combinations is carried out in the same way, following the above-described procedure. The process of generating the set of independent components is stopped when no reliable difference occurs any more between the probabilities of errors in recognizing situations belonging to the accepted classes. In this case, the previous set of independent components is the desired result. In contrast to the traditional methodology based on the Pearson criterion, the proposed approach allows us to bypass a problem of the decomposition of the range of values of random variables into multidimensional intervals. The method of generating a set of independent components of a multidimensional random variable is illustrated by the results of the analysis of spectral features of remote sensing data of forest tracts using space imagery from the Landsat-8 satellite.

643-653

Authors: V.V. Kotlyar, A.G. Nalimov, S.S. Stafeev, A.A. Kovalev

It is theoretically and numerically shown that when tightly focusing an n-th order vector light field that has the central V-point (at which the linear polarization direction is undetermined), the polarization singularity index n, and a "flower"-shaped intensity pattern with 2(n-1) lobes it forms a transverse intensity distribution with 2(n-1) local maxima. At the same time, a vector light field with the polarization singularity index -n, which has the form of a "web" with 2(n+1) cells generates at the sharp focus a transverse intensity distribution with 2(n+1) local maxima. In the focal spot, either 2(n-1) or 2(n+1) V-point polarization singularities with alternating indices +1 or -1 are formed at the intensity zero.

661-666

Authors: E.A. Bibikova, N.D. Kundikova, A.A. Shulginov, N. Al-Wassiti

The spin angular momentum and the extrinsic orbital angular momentum of light are associated with the polarization of light and the light propagation trajectory, respectively. Those momenta are interdependent not only in an inhomogeneous or anisotropic medium but even in free space. This interaction is called the spin-orbit interaction of light. The effects of the spin-orbit interaction of light manifest themselves in a small transverse shift of the beam field longitudinal component from the beam propagation axis in the waist region under the circular polarization sign change. They can be observed both for Gaussian beams and for structured beams. The effects of the spin-orbit interaction of light should be taken into account when nanophotonics devices are created, but the detailed investigation of the effect had not been performed yet due to the low intensity noise image of the beam waist. Precise measurements of the focal waist centerline are needed to determine the transverse shift of the beam field longitudinal component of the asymmetric converging beam's waist under the circular polarization sign change. We propose methods for determining the transverse and longitudinal positions of the beam waist. Computer image processing methods made it possible to obtain the value of the beam waist's transverse position with an accuracy of 0.1 mkm. These methods will allow further testing of the shifts' theoretical predictions, the values of which are the order of 1 mkm. The results obtained can also be used for laser processing of materials by polarized light and precise positioning of the beam's focal spot at a surface.

673-677

Authors: V.S. Pavelyev, K.N. Tukmakov, A.S. Reshetnikov, V.V. Gerasimov, N.D. Osintseva, B.A. Knyazev

Experimental results of the investigation of self-healing properties of terahertz Bessel beams with orbital angular momentum (OAM) with topological charges of l=3 and l=4 in free space after passing through a dispersive medium are presented.

685-691

Authors: S.S. Stafeev, V.D. Zaicev

It is shown theoretically and numerically that circularly and linearly polarized incident beams produce at the tight focus identical circularly symmetric distributions of an on-axis energy flux. It is also shown that the on-axis energy fluxes from radially and azimuthally polarized optical vortices with unit topological charge are equal to each other. An optical vortex with azimuthal polarization is found to generate the minimum focal spot measured for the intensity (all other parameters being equal). Slightly larger (by a fraction of a percent) is the spot size calculated for the energy flux for the circularly and linearly polarized light. The spot size in terms of intensity is of importance in light-matter interaction, whereas the spot size in terms of energy flux affects the resolution in optical microscopy.

702-712

Authors: D.V. Tropin, A.M. Ershov, D.P. Nikolaev, V.V. Arlazarov

The demand for on-device document recognition systems increases in conjunction with the emergence of more strict privacy and security requirements. In such systems, there is no data transfer from the end device to a third-party information processing servers. The response time is vital to the user experience of on-device document recognition. Combined with the unavailability of discrete GPUs, powerful CPUs, or a large RAM capacity on consumer-grade end devices such as smartphones, the time limitations put significant constraints on the computational complexity of the applied algorithms for on-device execution. In this work, we consider document location in an image without prior knowledge of the document content or its internal structure. In accordance with the published works, at least 5 systems offer solutions for on-device document location. All these systems use a location method which can be considered Hough-based. The precision of such systems seems to be lower than that of the state-of-the-art solutions which were not designed to account for the limited computational resources. We propose an advanced Hough-based method. In contrast with other approaches, it accounts for the geometric invariants of the central projection model and combines both edge and color features for document boundary detection. The proposed method allowed for the second best result for SmartDoc dataset in terms of precision, surpassed by U-net like neural network. When evaluated on a more challenging MIDV-500 dataset, the proposed algorithm guaranteed the best precision compared to published methods. Our method retained the applicability to on-device computations.

721-727

Authors: A.D. Fida, A.V. Gaidel, N.S. Demin, N.Yu. Ilyasova, E.A. Zamytskiy

We discuss approaches to combining multimodal multidimensional images, namely, three-dimensional optical coherence tomography (OCT) data and two-dimensional color images of the fundus. Registration of these two modalities can help to adjust the position of the obtained OCT images on the retina. Some existing approaches to matching fundus images are based on finding key points that are considered invariant to affine transformations and are common to the two images. However, errors in the identification of such points can lead to registration errors. There are also methods for iterative adjustment of conversion parameters, but they are based on some manual settings. In this paper, we propose a method based on a full or partial search of possible combinations of the OCT image transformation to find the best approximation of the true transformation. The best approximation is determined using a measure of comparison of preprocessed image pixels. Further, the obtained transformations are compared with the available true transformations to assess the quality of the algorithm. The structure of the work includes: pre-processing of OCT and fundus images with the extraction of blood vessels, random search or grid search over possible transformation parameters (shift, rotation and scaling), and evaluation of the quality of the algorithm.

736-748

Authors: A.S. Konushin, B.V. Faizov, V.I. Shakhuro

Traffic sign recognition is a well-researched problem in computer vision. However, the state of the art methods works only for frequent sign classes, which are well represented in training datasets. We consider the task of rare traffic sign detection and classification. We aim to solve that problem by using synthetic training data. Such training data is obtained by embedding synthetic images of signs in the real photos. We propose three methods for making synthetic signs consistent with a scene in appearance. These methods are based on modern generative adversarial network (GAN) architectures. Our proposed methods allow realistic embedding of rare traffic sign classes that are absent in the training set. We adapt a variational autoencoder for sampling plausible locations of new traffic signs in images. We demonstrate that using a mixture of our synthetic data with real data improves the accuracy of both classifier and detector.

756-766

Authors: Yu.V. Vizilter, O.V. Vygolov, S.Yu. Zheltov

We introduce attribute and relational representations of mosaic image models with directed relationships between regions. Attribute representations of asymmetric relational models based on stacking, ranking and integral descriptions are considered. We propose some morphological shape similarity measures based on relational models. We show that using the same oriented relational model, various morphological operators can be constructed, in particular, of Serra- or Pyt’ev type. Some constructive methods for the design of such morphological operators in an attribute and relational domains are proposed. From this consideration we also extract a new morophlogical scheme for two-stage mutual adaptive image-and-shape joint filtering: at the first step, the shape is simplified (projected) with regard to the image to be projected, and at the second step, the image is simplified (projected) with regard to the simplified (projected) shape.

773-778

Authors: A.S. Mokeev, V.M. Yamshchikov

We discuss features of the calculation of a Fraunhofer integral by traditional quadrature numerical integration methods and a special collocation Levin method when calculating the diffraction of a plane electromagnetic wave by a rectangular aperture. For the quadrature numerical integration methods, a criterion for the assessment of the integration step is derived depending on the screen size and required calculation accuracy. Advantages of the use of the special collocation Levin method in comparison with the traditional quadrature numerical integration methods are shown.

475-481

Authors: Editorial

Вы держите в руках или просматриваете на сайте 100-й выпуск журнала «Компьютерная оптика». Начав издаваться 34 года назад, с 1987 года, журнал прошёл плодотворный путь в своём становлении как ведущее международное научное издание, привлекающее внимание не только отечественных специалистов, но и ученых со всех уголков планеты. Из научного сборника с периодичностью 1 – 2 выпуска в год издание в 2007 году выросло до регулярного журнала с 4-мя, а начиная с 2016 года – 6-ю номерами в год, в которых ежегодно публикуется более 120 статей.

490-496

Authors: V.V. Kotlyar

In optical data transmission with using vortex laser beams, data can be encoded by the topo-logical charge, which is theoretically unlimited. However, the topological charge of a single sepa-rate vortex is limited by possibilities of its generating. Therefore, in this work, we analyze light beams with an unbounded (countable) set of optical vortices. The summary topological charge of such beams is infinite. Phase singularities (isolated intensity nulls) in such beams typically have a unit topological charge and reside equidistantly (or not equidistantly) on a straight line in the beam cross section. Such beams are form-invariant and, on propagation in space, change only in scale and rotate. Orbital angular momentum of such multivortex beams is finite, since only a finite number of optical vortices fall into the area, where the Gaussian beam has a notable intensity. Other phase singularities are located in the periphery (and at the infinity), where the intensity is almost zero.

506-511

Authors: V.V. Kotlyar, A.A. Kovalev, D.S. Kalinkina, E.S. Kozlova

In this paper, we consider a new type of Bessel beams having Fourier-invariance property and, therefore, called Fourier-Bessel beams. In contrast to the known Bessel beams, these beams have weak side lobes. Analytical expressions for the complex amplitude of the proposed field in the initial plane of the source and in the far field region have been obtained. It is shown that the proposed Fourier-Bessel beams have a finite energy, although they do not have a Gaussian envelope. Their complex amplitude is proportional to a fractional-order Bessel function (an odd integer divided by 6) in the initial plane and in the Fraunhofer zone. The Fourier-Bessel modes have a smaller internal dark spot compared to the Laguerre-Gauss modes with a zero radial index. The proposed beams can be generated with a spatial light modulator and may find uses in telecommunications, interferometry, and the capture of metal microparticles.

520-524

Authors: S.S. Stafeev

We have shown that a reverse energy flow (negative projection of the Poynting vector onto the optical axis) at the sharp focus of an optical vortex with topological charge 2 and left-hand circular polarization arises because the axial spin flow has a negative projection onto the optical axis and is greater in magnitude than positive projection onto the optical axis of the orbital energy flow (canonical energy flow). Also, using the Richards-Wolf formulas, it is shown that when focusing a left-handed circularly polarized light, in the region of the on-axis reverse energy flow, the light is right-handed circularly polarized.

534-540

Authors: J.D. Arango, Y.A. Vélez, V.H. Aristizabal, F.J. Vélez, J.A. Gómez, J.C. Quijano, J. Herrera-Ramirez

The response of fiber specklegram sensors (FSSs) is given as function of variations in the intensity distribution of the modal interference pattern or speckle pattern induced by external disturbances. In the present work, the behavior of a FSS sensing scheme under thermal perturbations is studied by means of computational simulations of the speckle patterns. These simulations are generated by applying the finite element method (FEM) to the modal interference in optical fibers as a function of the thermal disturbance and the length of the sensing zone. A correlation analysis is performed on the images generated in the simulations to evaluate the dependence between the changes in the speckle pattern grains and the intensity of the applied disturbance. The numerical simulation shows how the building characteristic of the length of sensing zone, combined with image processing, can be manipulated to control the metrological performance of the sensors.

551-561

Authors: A.V. Pavlov

The article is dedicated to the search for a biologically motivated mechanism of the cognitive phenomenon of violation of the classical formula of total probability for the disjunction of incompatible events, which is considered by a number of researchers as a quantum-like phenomenon. A classical mechanism implemented by the 6f Fourier holography scheme of the resonant architecture that does not require reference to quantum mechanics either in its physical nature or at the level of formalism is demonstrated. In the analysis, the decision-making is interpreted as a choice of alternatives by using the non-cooperative game "Prisoner's Dilemma". The approach to the task is based on the search for a mechanism for forming a conditional estimate under a condition that contradicts the rule of monotonous decision logic. It is demonstrated that this estimate, in contrast to the unconditional and conditional one with a non-contradictory condition, is formed by logic with exception. The ring architecture of the holographic setup corresponds to the biologically inspired neural network concept of the excitation ring and implements cognitive dissonance on logic with exception. Conditions and ranges of violation of the classical formula of total probability in relation to the correlation radius of the reference image recorded in a hologram storing the monotone logic inference rule are analytically determined. The analytical model is confirmed by a quantitative coincidence of the results of numerical modeling with the published results of natural experiments.

575-579

Authors: D.A. Gavrilov

The paper investigates the applicability of the convolutional neural network "U-Net" to a problem of segmentation of aircraft images. The neural network image segmentation method is based on the "Carvana" implementation with the "U-Net" architecture. For orientation recognition, a neural network built in the Keras open neural network library based on the pretrained VGG16 neural network is used. The approach considered allows the image segmentation to be conducted. The results of the experiments have shown the possibility of a fairly accurate selection of the object of interest. The resulting binary masks make it possible to visually classify the aircraft in the image.

589-599

Authors: I.A. Kudinov, M.B. Nikiforov, I.S. Kholopov

We derive analytical expressions for calculating the number of elementary computational operations required to generate several personal regions of interest in a panoramic computer-vision distributed-aperture system using two alternative strategies: strategy 1 involves acquisition of a complete panoramic frame, followed by the selection of personal regions of interest, while with strategy 2 the region of interest is directly formed for each user. The parameters of analytical expressions include the number of cameras in the distributed system, the number of users, and the resolution of panorama and user frames. The formulas obtained for the given parameters make it possible to determine a strategy that would be optimal in terms of a criterion of the minimum number of elementary computational operations for generating multiple personal regions of interest. The region of interest is generated using only a priori information about the internal and external camera parameters, obtained as a result of their photogrammetric calibration with a universal test object, and does not take into account information about scene correspondences at the boundaries of intersecting fields of view.

608-614

Authors: A.V. Uzhinskiy, G.A. Ososkov, P.V. Goncharov, A.V. Nechaevskiy, A.A. Smetanin

Triplet loss function is one of the options that can significantly improve the accuracy of the One-shot Learning tasks. Starting from 2015, many projects use Siamese networks and this kind of loss for face recognition and object classification. In our research, we focused on two tasks related to vegetation. The first one is plant disease detection on 25 classes of five crops (grape, cotton, wheat, cucumbers, and corn). This task is motivated because harvest losses due to diseases is a serious problem for both large farming structures and rural families. The second task is the identification of moss species (5 classes). Mosses are natural bioaccumulators of pollutants; therefore, they are used in environmental monitoring programs. The identification of moss species is an important step in the sample preprocessing. In both tasks, we used self-collected image databases. We tried several deep learning architectures and approaches. Our Siamese network architecture with a triplet loss function and MobileNetV2 as a base network showed the most impressive results in both above-mentioned tasks. The average accuracy for plant disease detection amounted to over 97.8% and 97.6% for moss species classification.

627-637

Authors: V.V. Syuzev, E.V. Smirnova, A.V. Proletarsky

The article discusses two approaches to modeling signals and processes: the method of filter construction and the trigonometric method. It is shown that the later approach is more promising, since an increase in the signal/process representation dimension mathematically means adding a term to the basis function formula, which gives access to fast simulation algorithms. Examples of algorithms for multidimensional simulation of random processes using two methods are given and a software system that implements these algorithms is described. The results provided by the software system will allow you to predict characteristics of engineering projects (accuracy and speed of modeling algorithms). Due to the high relevance of and need for fundamental research of methods and algorithms for digital transformation of the component base, the digitalization of all aspects of activity, including the synthesis of new materials, the development of new methods for designing micro- and nano-systems, the article aims to expand the scope of the spectral method of simulating multidimensional processes using original algorithmic complexes.