Computer Optics

5-12

Authors: Kotlyar V.V., Kovalev A.A.

We obtain general analytic expressions for the angular momentum density of a vectorial circularly polarized paraxial optical vortex. It is shown that for any vortex field with the rotational symmetry and circular polarization, an effect of the “angular tractor” takes place, which means that the flow of light energy rotates around the optical axis clockwise or counter-clockwise at different radii in the beam cross section. It is also shown that on the circles of these radii in the beam cross section, the axial component of the angular momentum density of the vortex light field changes its sign. Thus, microparticles trapped in the vortex beam at different radii will rotate either clockwise or counterclockwise.

22-27

Authors: Bezus E.A., Bykov D.A., Doskolovich L.L.

We consider the derivation of a dispersion relation of Bloch surface waves supported by interfaces between a semi-infinite one-dimensional photonic crystal and a homogeneous medium. From the derived dispersion relation, we obtain an explicit analytical expression that defines the relationship between the propagation constant and the thickness of the upper layer of the photonic crystal.

38-43

Authors: Greisukh G.I., Danilov V.A., Antonov A.I., Stepanov S.A., Usievich B.A.

Spectral and angular dependences of the diffraction efficiency of two-layer single-relief sawtooth microstructures are analyzed. The microstructures are assembled from optical plastics and new brands of special optical glass. This makes it easy to replicate elements with diffraction microrelief by precision casting or stamping. Wide possibilities of weakening the dependence of the diffraction efficiency of such microstructures on the wavelength and the angle of incidence of radiation on the element are demonstrated.

54-59

Authors: Usanov D.A., Skripal A.V., Astakhov E.I., Kostuchenko I.S., Dobdin S.Yu.

The capabilities of the method of current-modulated laser wavelength are shown to be extended by using harmonic modulation. Advantages of the sawtooth modulation method associated with using the frequency measurements of the interference signal as an information parameter have been researched. Advantages of the harmonic-type modulation based on the use of measurement results for spectral component amplitudes of the interference signal for distance determination have also been investigated. A comparative analysis of methods for absolute distance measurements at the existing capabilities of semiconductor laser wavelength modulation has demonstrated the benefits of the harmonic modulation of laser diode current for distances under 30 cm, showing the sawtooth current modulation to work better for distances greater than 50 cm.

67-71

Authors: Volkov O.A., Demin A.V., Konstantinov K.V.

Principles of constructing an optical sensor for measuring a meteorological visibility range are considered. A new relationship for the visibility range determination is obtained. An optical scheme of the meteorological visibility range sensor is described and characteristics of the new sensor are presented.

84-95

Authors: Labunets V.G., Kokh E.V., Ostheimer E.

We present a new theoretical framework for multichannel image processing using commutative hypercomplex algebras. Hypercomplex algebras generalize the algebras of complex numbers. The main goal of the work is to show that hypercomplex algebras can be used to solve problems of multichannel (color, multicolor, and hyperspectral) image processing in a natural and effective manner. In this work, we suppose that the animal brain operates with hypercomplex numbers when processing multichannel retinal images. In our approach, each multichannel pixel is considered not as an K–D vector, but as an K–D hypercomplex number, where K is the number of different optical channels. The aim of this part is to present algebraic models of subjective perceptual color, multicolor and multichannel spaces.

105-112

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

In this work, we research the applicability of generative adversarial neural networks for generating training samples for a traffic sign classification task. We consider generative neural networks trained using the Wasserstein metric. As a baseline method for comparison, we take image generation based on traffic sign icons. Experimental evaluation of the classifiers based on convolutional neural networks is conducted on real data, two types of synthetic data, and a combination of real and synthetic data. The experiments show that modern generative neural networks are capable of generating realistic training samples for traffic sign classification that outperform methods for generating images with icons, but are still slightly worse than real images for classifier training.

118-127

Authors: Mitekin V.A., Fedoseev V.A.

The paper proposes two information hiding algorithms for multimedia based on Quantization Index Modulation (QIM): IM-QIM and SIM-QIM. They are designed to prevent a statistical attack which is able to restore a secret key using the correlation between key bits and multimedia data samples. To obtain the required security, we use a correlation immune embedding function, which guarantees statistical independence between the watermarked data and the key. The proposed algorithms are described for the case of spatial embedding in images but the algorithms can also be used to hide information in any multimedia data source in spatio-temporal and spectral domains. The results of the experimental investigation have confirmed that the algorithms developed provide the required security against a statistical attack and also have shown that the algorithms do not introduce additional distortions compared with the conventional QIM method. However, the experiments have also shown that the new algorithms are less robust against additive noise and JPEG compression.

141-148

Authors: Blokhinov Y.B., Gorbachev V.A., Rakutin Y.O., Nikitin D.A.

We propose a novel effective algorithm for real-time semantic segmentation of images that has the best accuracy in its class. Based on a comparative analysis of preliminary segmentation methods, methods for calculating attributes from image segments, as well as various algorithms of machine learning, the most effective methods in terms of their accuracy and performance are identified. Based on the research results, a modular near real-time algorithm of semantic segmentation is constructed. Training and testing is performed on the ISPRS Vaihingen collection of aerial photos of the visible and IR ranges, to which a pixel map of the terrain heights is attached. An original method for obtaining a normalized nDSM for the original DSM is proposed.

159-166

Authors: Khorin P.A., Ilyasova N.Yu., Paringer R.A.

The study was devoted to the analysis of wavefront aberrations under changes of the cornea surface curvature in the human eye. The analysis was based on the representation of aberrations of the front and rear corneal surfaces as superposition of Zernike functions. Weight coefficients of the Zernike polynomials were the object of this study. The data under analysis were obtained in a number of clinical trials in the Branchevski’s eуе clinic. The most informative weight coefficients were analyzed from the point of view of classification of patients by particular diagnosis. A comparison of the classification results was carried out using thirty front and rear corneal features, as well as the most informative features. The features were ranked by the informativity criterion for solving a specific classification task. While doing analysis, the informativity was evaluated on the basis of values of a separability criterion. An additional estimation of informativeness was carried out by calculating the classification error by a K-means method. As a result of the analysis, basic Zernike functions that are most informative for particular eye pathologies were identified.

791-795

Authors: O. Korotkova

The polarization properties of the recently introduced three-dimensional electromagnetic Gaussian Schell-model sources [Opt. Lett. 42, 1792 (2017)] are examined. Both cases of uniform and non-uniform polarization are considered. The three-dimensional polarization states are characterized via the eigenvalues of a 3×3 source polarization matrix and, more specifically, via the indices of polarimetric purity. We show that the considered sources exhibit a variety of polarization states throughout their volumes conveniently controlled by several physically accessible source parameters.

803-811

Authors: A.B. Sotsky, A.V. Shilov, L.I. Sotskaya

Relations are obtained that make it possible to compute the field of the wide-band terahertz pulse in capillary waveguides with a hollow core and a metalized cladding. From the standpoints of maximization of the pulse energy transfer coefficient and time-domain spectroscopy of air, two types of waveguides are investigated: hollow waveguides with a metalized cladding and dielectric-lined waveguides whose hollow core is separated from the metal by a dielectric layer. It is shown that the efficiency of the waveguides of the second type is higher due to their quasi-single-mode operation.

820-830

Authors: D.G. Denisov

A dynamic interferometry method for controlling nano-scale local deviations of optical surfaces from a prescribed profile is developed, theoretically substantiated, and experimentally verified on the basis of an algorithm for calculating an objective function, defined as the spectral density of a one-dimensional correlation function. Theoretical and experimental approaches to determining the root-mean-square error when finding local deviations of the optical surfaces for the element diameters ranging from 100 mm to 1,000 mm are presented, while taking into account the non-excluded systematic and random error components in determining the objective function.

837-841

Authors: V.D. Paranin, S.V. Karpeev, O.G. Babaev

A method for the investigation of birefringence of mechanically free parabolic gradient-index lenses based on the astigmatic transformation of a zero-order Bessel beam has been experimentally verified. Special features of the alignment of the optical setup are described and practical recommendations for selecting the setup components are given. By the example of a quarter-wave lens, we show experimentally that the optical path difference can be reliably measured within a 0.05λ0 accuracy. A significant difference between the birefringence properties of the gradient-index lenses in their central and edge regions is confirmed.

848-855

Authors: S.P. Murzin, G. Liedl

A use of laser technology it is progressive in the welding of dissimilar materials. Pulsed laser welding of an aluminum alloy AK4 and a titanium alloy VT5-1 was performed. Processing conditions were determined, the realization of which during melting of materials in the heat-affected zone makes it possible to obtain a homogeneous structure without voids and shells, potentially producing sufficiently sound welded joints. To create the required power density distribution across the laser beam, it was found expedient to use diffractive optical elements. Aluminum and copper were welded by continuous laser beam. It is determined that laser action with its well-defined and precise localized heat input makes it possible to significantly reduce the growth of intermetallic compound layers.

864-868

Authors: K.M. Bulatov, Y.V. Mantrova, A.A. Bykov, M.I. Gaponov, P.V. Zinin, A.S. Machikhin, I.A. Troyan, V.I. Batshev, I.B. Kutuza

In this paper, we demonstrate that combining a laser heating (LH) system with a tandem acousto-optical tunable filter (TAOTF) allows us to measure the temperature distribution (TD) across a laser-heated microscopic specimen. Spectral image processing is based on one-dimensional (1D) non-linear least squares fitting of the Planck radiation function. It is applied for determining the temperature T at each point (x, y) of the specimen surface. It is shown that spectral image processing using the 1D non-linear least squares fitting allows measurement of the TD of the laser-heated microscopic specimen with higher precision and stability than those of the conventional linear least-squares fitting of the Wien approximation of Planck’s law.

875-887

Authors: A.V. Nikonorov, M.V. Petrov, S.A. Bibikov, V.V. Kutikova, A.A. Morozov, N.L. Kazanskiy

In recent years, several pioneering works were dedicated to imaging systems based on simple diffractive structures like Fresnel lenses or phase zone plates. Such systems are much lighter and cheaper than classical refractive optical systems. However, the quality of images obtained by diffractive optics suffers from stronger distortions of various types. In this paper, we show that a combination of the high-precision lens design with post-capture computational reconstruction allows one to attain a much higher image quality. The proposed reconstruction procedure uses a sequence of color correction, deconvolution, and a feedforward deep learning neural network. An improvement both in lens manufacturing and in image processing may contribute to the emergence of ultra-lightweight imaging systems varying from cameras for nano- and picosatellites to surveillance systems.

897-904

Authors: N.A. Smelkina, R.N. Kosarev, A.V. Nikonorov, I.M. Bairikov, K.N. Ryabov, A.V. Avdeev, N.L. Kazanskiy

We propose a method of statistical shape modeling applied to reconstructing anatomical structures with deformations. This method is promising for modeling deformed body parts that have a certain normal shape. The method of statistical shape modeling allows one to reconstruct a deformed object using information about the normal shape of the body part and its undeformed fragment, while taking into account peculiar individual features and the variability relative to the average shape.

913-919

Authors: Y.D. Vybornova, V.V. Sergeev

In this paper, we propose a new digital watermarking method for protecting of vector data in geographic information systems. The method is based on a combination of two novel approaches. Firstly, the watermark information is embedded into the polygon map objects by cyclically shifting the list of vertices of each polygon. Secondly, instead of a bit vector, a raster image superimposed on the map is considered as a watermark. The major advantage of this method is that it does not distort the map by altering the coordinate values. A simple example demonstrates the method efficiency, as well as the robustness of the embedded watermark against geometric transformations usually performed when working with map data: translation, scaling, rotation and cropping.

931-937

Authors: I.V. Borisova, V.N. Legkiy, S.A. Kravets

In this paper, a problem of automatic target tracking in complex natural backgrounds is considered. Target detection is performed in each frame of a video sequence by the elementwise comparison with a reference image. The proposed method is based on the representation of every pixel as the orientation of the luminance gradient in the vicinity. The vicinities are divided into classes depending on their orientation. In addition to the classes of anisotropic vicinities, a class of vicinities with an isotropic structure is introduced. The classes are numbered and the number of the vicinity class is used as a feature of the point of interest. Thus, the original gray-scale image is transformed to a pseudo-image in which the detection procedure is carried out. The encoded image is then scanned using a reference image. The elementwise comparison of the reference image with the current fragment is performed in a feature space. As a result, a comparison matrix is formed, each element of which is the number of matching elements of the reference image and the current image fragment. The position of the reference image is determined by the maximum value of the comparison matrix. A special rule of reference image overwriting, the so-called dynamic proximity measure, is used to achieve stable tracking. The testing results have shown that with our approach the object tracking is more stable in comparison with the use of normalized correlation.

950-956

Authors: T.V. Yakovleva

The paper presents a new technique for the accurate measurement of the phase difference between two quasi-harmonic optical signals through analyzing and processing their envelope values obeying the Rice statistical distribution. With this technique, the envelope values of three signals are measured: two initial quasi-harmonic signals for which the phase difference is measured and a third signal formed as superposition of the first two. The phase shift under measurement is calculated from simple geometrical considerations as the angle of a triangle formed by the amplitude values of the reconstructed undistorted signals. The fundamental distinction of the proposed technique consists in the fact that the phase characteristics are derived from the amplitude measurements alone, thus significantly mitigating the requirements imposed on the equipment and simplifying the practical implementation of the method. It is proposed that the undistorted amplitudes should be estimated using methods of the Rician data analysis. The paper provides a strict mathematical analysis of the problem and computer simulation results. The ability to conduct accurate phase shift measurements based on the proposed method is useful for a wide range of applied tasks solved in numerous ranging and communication systems.

963-972

Authors: A.V. Vorobev, G.R. Vorobeva

We present and describe a method to conduct correlation and amplitude-frequency analysis of the observational data of geomagnetic variations and space weather that is based on the combined use of a concept of single information space, models and methods of wavelet and Fourier analysis, and geo-information technologies. The method includes formalized elements of mathematical and methodological support for conducting amplitude-frequency and correlation analysis of the observations of geomagnetic variations and space weather and is verified by means of a prototype in-house platform-independent web-oriented geoinformation system GEOMAGNET (https:// www.geomagnet.ru). The proposed method is verified using data obtained from the magnetic observatories of the INTERMAGNET network and space weather data from the artificial Earth satellite ACE. Results of the observation, automated correlation and amplitude-frequency analysis of signals that provide information on the geomagnetic field and space weather variations at specified time intervals both on the Earth's surface and in near-Earth space are discussed and evaluated.

599-608

Authors: A.V. Dyshlyuk, O.B. Vitrik, Yu.N. Kulchin

In this paper, we present a numerical study of surface plasmon resonance (SPR) excitation in a bent single-mode optical fiber with metallized cladding. It is shown that with a suitable combination of the bending radius and metal film thickness, surface plasmon waves can be excited in the film as a result of coupling between the fundamental and surface plasmon modes via whispering gallery modes (WGM) supported by the bent fiber cladding. The coupling brings about a dip in the transmission spectrum at the resonant wavelength which is strongly dependent on the ambient refractive index, thus, making it possible to build an SPR- refractometer based on a single-mode fiber without breaking the structural integrity of the fiber or using any additional elements. The refractometric sensitivity of ~12 µm/RIU are demonstrated.

617-625

Authors: A.V. Ustinov

This work deals with a detailed theoretical study of Hermite-Gauss beams with embedded vortical phase passing through a lens. Special attention is given to the location of vortical phase singularities in the focal plane. Sufficient conditions for the intensity null in the focal plane centre are found. The theoretical analysis is confirmed by numerical calculations.

636-644

Authors: N.S. Zakharov , S.V. Kholod

Results of the numerical calculation of the envelope and frequency profile of a pulse propagating in a dispersive medium, exemplified by the propagation of a femtosecond pulse in the plasma, are presented. The explanation for the appearance of modulation in the odd orders of approximation of the theory of dispersion and for the extinction of modulation in the even orders is given. Taking into account the fourth-order term of the approximate dispersion theory is shown to be sufficient in the majority of cases when calculating the ultrashort pulse propagation.

655-660

Authors: A.G. Nalimov

Using the numerical solution of differential Maxwell’s equations, we show that a binary microlens with unit numerical aperture (NA = 1) manufactured in a thin-film amorphous silicon focuses the laser light into a near-surface subwavelength optical focal spot. The microlens contains sectored subwavelength diffraction gratings operating as half-wave plates. The incident light is a linearly polarized plane wave. The micrometalens is numerically shown to operate with near-same efficiency with the number of sectored grating varying from 3 to 16. It is shown that a 16-sector micrometalens generates a focal spot of size at the full-width at half-maximum intensity of FWHMx = 0.435λ and FWHMy = 0.457λ along the Cartesian axes, where λ is the incident wavelength. A 4-sector microlens is numerically shown to focus light into a focal spot of size FWHMx = 0.428λ and FWHMy = 0.46λ.

670-679

Authors: A.A. Dyachenko, V.P. Ryabukho

Regular features in generating coloured interference patterns from single-layer thin objects in polychromatic optical microscopy are considered. Expressions for the intensity distribution of the image interference fields are obtained with due account for the spectral properties of radiation. The proposed algorithm for computer-aided calculation and generation of coloured interference patterns in white light depending on the optical thickness of the layered object is based on a RGB colour model. Numerically simulated interference patterns are presented and changes in their colour and structure under varying parameters of the microscope optical scheme and object optical properties are discussed. We show that it is possible to determine the optical thickness of the object layer through the numerical comparison of interference colours obtained in the natural and numerical experiments.

687-693

Authors: A.G. Glushchenko, E.P. Glushchenko, E.S. Ustinova

The paper considers peculiar features of the Doppler effect that occurs when fundamental and higher-order modes reflect at a movable dielectric layer in multimode waveguides. Relationships for calculating frequencies of different modes of waves that reflect at and pass through the dielectric layer are derived. It is established that with increasing order of the mode, its frequency gets less dependent on the layer motion rate for the reflected waves, at the same time showing a stronger dependence for the transmitted waves. The interaction of waves with the inhomogeneous movable layer leads to the excitation of higher-order modes of the reflected and passed waves, so that each mode corresponds to a different frequency shift (multi-frequency Doppler effect).

701-711

Authors: A.V. Kokoshkin, V.A. Korotkov, K.V. Korotkov, E.P. Novichikhin

This work shows the possibility of estimating errors of super-resolution imaging based on the use of several frames. The possibility of identifying areas with large interpolation errors is shown, based only on the interpolation method and interpolated data used. The possibility of determining the necessary number of frames used for imaging from the interpolation error estimate is demonstrated. In this paper, we present both the results of interpolation of the generated test frames, the method of correlation subpixel detection of frame shifts relative to 1 frame, and the estimates of the resulting interpolation errors. It is shown that before measurements, the number of frames necessary to achieve the required level of interpolation errors can not be predicted. The proposed method allows the error value to be controlled during the measurement. It is shown that the estimation of errors of the super resolution method based on test images is not very promising, since the error value depends both on the image itself and on a set of subpixel offsets of low-resolution frames. We discuss the entire procedure of obtaining the results of the work, starting from the test image generation and ending with the conclusions.

719-725

Authors: E.A. Terekhin

This paper explores the potentialities of discriminant analysis for the identification of abandoned agricultural lands using their reflectance spectrum properties. A method of automated detection of fallow lands is proposed. Using experimental data received from the agricultural lands of the Belgorod Region, we propose equations that allow an agrarian land to be classified as an arable or fallow land in an automated mode. The accuracy of fallow land recognition is 71%. It is found that seasonal normalized difference vegetation index (NDVI) values computed from MODIS data in the period of late September - early October are most informative in terms of abandoned agricultural land identification. It is shown that the use of the minimal NDVI values is much more efficient for the identification of fallow land when compared with the mean NDVI values.

732-742

Authors: M.Yu. Nikitin, V.S. Konushin, A.S. Konushin

This paper addresses a problem of video-based face recognition. We propose a new neural network model that uses an input set of facial images of a person to produce a compact, fixeddimension descriptor. Our model is composed of two modules. The feature embedding module maps each image onto a feature vector, while the face quality assessment module estimates the utility of each facial image. These feature vectors are weighted based on their utility estimations, resulting in the image set feature representation. During visual analysis we found that our model learns to use more information from high-quality face images and less information from blurred or occluded images. The experiments on YouTube Faces and Janus Benchmark A (IJB-A) datasets show that the proposed feature aggregation method based on face quality assessment consistently outperforms naïve aggregation methods.

756-764

Authors: A.S. Yumaganov, V.V. Myasnikov

The work is devoted to solving a problem of searching for similar code sequences in executable binary files. The proposed method involves partitioning the processor instructions into functional groups, forming a given function’s primary description by commands position in its body, followed by generating the function’s intermediate description through its comparison with the functions from a "base" library. With the dimensionality of the resulting vector reduced in this way, the resulting final description is then used to perform the search. Results of the experimental study demonstrate the operability of the proposed method. The efficiency of the proposed method is compared against existing methods of searching for similar code sequences. We also provide recommendations on the choice of parameters of the developed method.

775-785

Authors: D.A. Savelyev

The article gives a summary of major events of the 3rd International Conference and the Youth School on Information Technologies and Nanotechnology (ITNT-2017), which was held in Samara on April 25-27, 2017. Main research topics covered at ITNT-2017 are also briefly reviewed.

476-483

Authors: V.A. Saleev, A.V. Shipilova

We study optical properties of lowest-energy carbon allotropes in the infrared, visible and ultraviolet spectral ranges in the general gradient approximation of the density functional theory. In our calculations we use an all-electron approach as well as a pseudo-potential approximation. In the infrared range, complex dielectric functions, infrared and Raman spectra have been calculated using a CRYSTAL14 program. Electronic properties and energy-dependent dielectric functions in the visible and ultraviolet spectral ranges are calculated using a VASP program. We describe with good accuracy the experimentally known optical properties of a cubic diamond crystal. Using the obtained set of relevant calculation parameters, we predict the optical constants, dielectric functions and Raman spectra of the lowest-energy hypothetical carbon allotropes and lonsdaleite.

489-493

Authors: V.A. Burdin, A.V. Bourdine

Modern telecommunication networks approach the capacity crunch, which is associated with the so-called nonlinear Shannon limit. So, the passage to fiber optic links with few-mode optical fibers is considered as an alternative solution of the described problem concerned with high nonlinearity of conventional commercial single-mode optical fibers. Presently, various designs of few-mode optical fibers have been known, with the recently published works presenting experimental results demonstrating their potentialities for long-haul fiber optic links. A lot of models of long-haul fiber optic links with few-mode optical fibers have been developed based on which features of a few-mode optical fiber transport network were numerically simulated. This work presents the results of simulation of a 6000-km long-haul fiber optic link with a two-mode optical fiber and 100-km-per-span Erbium doped fiber optic amplifiers system under 100 Gbps DP-DQPSK data transmission. We studied the use of particular linearly polarized modes and optical vortices for signal transmission. The computation results were compared with the simulation of the same fiber optic link with a single-mode optical fiber under the identical conditions.

499-503

Authors: A. Rogozhin, M. Bruk, E. Zhikharev, F. Sidorov

A wide range of structures for nanophotonics and optoelectronics can be formed by dry e-beam etching of the resist (DEBER). High resist sensitivity due to chain depolymerization reaction provides efficient etching with high throughput of the method. The structures obtained by the DEBER in this research are well-rounded diffraction gratings, binary gratings and staircase profiles. The major disadvantage of DEBER is poor lateral resolution, which may be caused by different physical mechanisms. Four groups of possible mechanisms leading to the resolution limitation are determined and the influence of some mechanisms is estimated.

510-514

Authors: A.V. Gavrilov, V.S. Pavelyev

A transverse mode converter based on a binary microrelief implemented directly on the end-face of a few-mode fiber was numerically investigated. The results of numerical simulation demonstrated the converter to form LP-11 and LP-21 modes with high efficiency, providing a more-than 92 % mode purity. Transformations of modes excited by a fiber microbending were also numerically investigated. The excited beams were shown to save their mode purity even in a strong bending as the arising parasitical modes were mostly unguided by the fiber. The resulting beam power and mode content were also demonstrated to depend on the beam and bending mutual orientation for beams with strong rotational symmetry.

521-527

Authors: I.S. Zaqout

Hair occlusion in dermoscopy images affects the diagnostic operation of the skin lesion. Segmentation and classification of skin lesions are two major steps of the diagnostic operation required by dermatologists. We propose a new algorithm for hair removal in dermoscopy images that includes two main stages: hair detection and inpainting. In hair detection, a morphological bottom-hat operation is implemented on Y-channel image of YIQ color space followed by a binarization operation. In inpainting, the repaired Y-channel is partitioned into 256 non-overlapped blocks and for each block, white pixels are replaced by locating the highest peak, using a histogram function and a morphological close operation. The proposed algorithm reports a true positive rate (sensitivity) of 97.36 %, a false positive rate (fall-out) of 4.25 %, and a true negative rate (specificity) of 95.75 %. The diagnostic accuracy achieved is recorded at a high level of 95.78 %.

535-544

Authors: A.V. Gorevoy, A.S. Machikhin

Modern videoendoscopes are capable of performing precise three-dimensional (3D) measurements of hard-to-reach elements. An attachable prism-based stereo adapter allows one to register images from two different viewpoints using a single sensor and apply stereoscopic methods. The key condition for achieving high measurement accuracy is the optimal choice of a mathematical model for calibration and 3D reconstruction procedures. In this paper, the conventional pinhole camera models with polynomial distortion approximation were analyzed and compared to the ray tracing model based on the vector form of Snell’s law. We, first, conducted a series of experiments using an industrial videoendoscope and utilized the criteria based on the measurement error of a segment length to evaluate the mathematical models considered. The experimental results confirmed a theoretical conclusion that the ray tracing model outperforms the pinhole models in a wide range of working distances. The results may be useful for the development of new stereoscopic measurement tools and algorithms for remote visual inspection in industrial and medical applications.

552-558

Authors: M.S. Boori, K. Choudhary, R.A. Paringer, M. Evers

The central dry zone of Myanmar is the most water stressed and also one of the most food insecure regions in the country. In the Dry Zone, the total population is 10.1 million people in 54 townships, in which approximately 43 % of people live below the poverty line and 40 – 50 % of the rural population is landless. Agriculture is the most important economic sector in Myanmar as it is essential for the national food security and a major source of livelihood of the people. In this region the adverse effects of climate change such as a late or early onset of the monsoon season, longer dry spells, erratic rainfall, increasing temperatures, heavy rains, stronger typhoons, extreme spatial-temporal variability of rainfall, high intensities, limited rainfall events in the growing season, heat stress, drought, flooding, sea water intrusion, land degradation, desertification, deforestation, and other natural disasters are believed to be major constraints to food security. Theses extreme climatic events are likely to increase in frequency and magnitude, leading to serious drought periods and extreme floods. Food insecurity is an important thing that must be reviewed because it affects the lives of many people. For food vulnerability, we use the following indicators: slope, precipitation, vegetation, soil, erosion, land degradation and harvest failure in ArcGIS software. The erosion is influenced by rainfall and slope, while land degradation is directly related to vegetation, drainage and soil. In the meantime, the harvest failure can be generated by rainfall and flood potential zones. The results show that around 45 % of the area studied comes under a very high erosion danger level, 70 % are in the average harvest failure zone, 59 % are in the intermediate land degradation area, and overall around 45 % of the studied area comes under the insecure food vulnerability zone. Our analysis shows that an increase in the alluvial farming by 1745.33 km2 since 1988 has helped reduce the insecure food vulnerability. The food vulnerability map is also relevant to increased population and low income areas. This paper is helpful for identifying the areas of food needs in central dry zone of Myanmar.

564-572

Authors: E.V. Myasnikov

Unsupervised segmentation of hyperspectral satellite images is a challenging task due to the nature of such images. In this paper, we address this task using the following three-step procedure. First, we reduce the dimensionality of the hyperspectral images. Then, we apply one of classical segmentation algorithms (segmentation via clustering, region growing, or watershed transform). Finally, to overcome the problem of over-segmentation, we use a region merging procedure based on priority queues. To find the parameters of the algorithms and to compare the segmentation approaches, we use known measures of the segmentation quality (global consistency error and rand index) and well-known hyperspectral images.

577-580

Authors: V.A. Tkachenko, A.S. Tsipotan, A.S. Aleksandrovsky, V.V. Slabko

This study considered a process of quantum dots' self-assembly into nanostructure arrays with predefined geometry, which proceeds in the external resonant laser field. We considered the simplest case of assembling a stable structure of two particles. The problem was solved numerically using a three-dimensional model of Brownian dynamics. The idea of the method is that the attraction of the dots occurs due to the interaction of resonantly induced dipole moments, with the dots being then captured by the Van der Waals force. Finally, a three-dimensional model was considered; the average nanoparticle aggregation time as a function of the laser radiation wavelength was calculated; the probability of such structures' being formed was estimated for the calculated average aggregation time and for the laser pulse duration used in the experiment. The wavelength of the maximum probability was found to be shifted from the single particle resonance wavelength of 525 nm to the red area of 535 nm, which is in qualitative agreement with the redshift of the resonance wavelength of interacting particles.

585-587

Authors: N.S. Kravtsova, R.A. Paringer, A.V. Kupriyanov

This paper proposes a parallel implementation of the image informative segments extraction method. The images are segmented in the spatial spectrum domain. The median energy in each selected segment is viewed upon as an area. For purposes of time savings, a parallel implementation of the algorithm for calculating the areas is developed. The developed approach to the parallel algorithm implementation is tested on a high performance multicore computing system. The experiments have shown that the parallel implementation of the method allows us to obtain a three-fold speedup, which is a good result.

592

Authors: S.S. Stafeev

Inclusion of the journal Computer Optics in the Emerging Sources Citation Index database is described in this editorial.

299-314

Authors: S.S. Stafeev, A.G. Nalimov, L. O'Faolain, M.V. Kotlyar

Components of thin microoptics with nanostructured surface for polarization and phase control are investigated. These components include transmitting or reflecting subwavelength diffraction gratings that have space-variant direction and filling factor, but near-uniform period and depth of the relief, whose features can vary in size from dozens to hundreds of nanometers for the visible wavelength range. The sectoral diffractive polarizers with a small number of sectors, which transform linear polarization into radial or azimuthal polarization, and subwavelength binary microlenses for tight focusing of laser light are investigated in detail. Examples of specific micropolarizers and metalenses manufactured in amorphous silicon films are given.

322-329

Authors: E.A. Kadomina, E.A. Bezus, L.L. Doskolovich

A diffraction structure for generating high-frequency interference patterns of evanescent electromagnetic waves based on the interference of “volume” modes of dielectric photonic crystals at Fabry-Perot resonances is discussed. For the prediction of the angular locations of the Fabry-Perot resonances, a simple approach for the description of diffraction of a plane electromagnetic wave by a finite photonic crystal is proposed, which is based on the representation of the field inside the photonic crystal in the form of superposition of two counterpropagating “volume” modes of the photonic crystal. The results obtained may find an application in the design of new near-field interference lithography devices.

338-347

Authors: S.N. Khonina, S.G. Volotovsky, A.V. Ustinov, S.I. Kharitonov

The work is devoted to the theoretical and numerical investigation of the focusing properties of a harmonic lens with due regard for the refractive index dispersion. It is shown that the harmonic lens has hybrid refractive-diffractive properties, which are expressed not only in the appearance of additional local foci, but also in the displacement of the main focus even for aliquot wavelengths. The latter effect arises precisely because of the dispersion of the refractive index of the lens material.

356-362

Authors: A.G. Nalimov, S.S. Stafeev, E.S. Kozlova, V.V. Kotlyar, L. O'Faolain, M.V. Kotlyar

We study in which way the parameters of a focal spot generated by a chromium zone plate 15-µm in diameter synthesized by sputtering on a glass substrate and having a focal length equal to the incident wavelength of λ = 532 nm depend on the microrelief height. It is shown numerically that an optimal microrelief height of the zone plate is 70 nm. With these parameters, the minimal size of the focal spot is achieved. Using a scanning near field optical microscope the said zone plate is shown to focus a linearly polarized Gaussian beam into an elliptical focal spot having the full-width at half-maximum of FWHMx = 0.42λ and FWHMy = 0.64λ along the Cartesian axes.

369-376

Authors: A.V. Kalenskii, A.A. Zvekov, D.R. Nurmuhametov, O.N. Bulgakova

The main features of the photothermal mirror signals arising under the continuous wave excitation were analyzed in terms of a model that takes account of thermal, mechanical, and diffraction effects. Formulae to describe the initial slope and stationary value of the signal were derived and compared with the numerical simulation results. We suggested an approach to processing the thermal mirror signals based on exploiting the initial slope and stationary value. The method was verified using numerical simulation and experimental results. We compared the method performance with the conventional approach using thermal mirror signals excited in the luminescent glasses. It was shown that the developed technique has an essentially lower computational cost, while offering a comparable level of accuracy.

385-390

Authors: S.A. Matyunin, O.G. Babaev

At present, in polarization-based optical fiber sensors the optical fiber is used both as a sensitive element (SE) and as fiber-optic communication lines (FOCL) for transmission of an optical signal. In such sensors, the polarization axes of the optical radiation source (ORS) and SE need to be aligned. However, FOCL elements located between the ORS and SE introduce their own polarization distortions due to the anisotropy of the optical properties of the fiber resulting from bending deformations of a random nature. This leads to a decrease in the accuracy and repeatability of the polarization sensor (PS) measurements. The proposed method of polarization correction consists in depolarization (transformation into circular polarization) of optical radiation by placing coils with an optical fiber between the ORS and SE, and certain parameters: the diameter of the coil, the number of turns and the angle of rotation of the coil relative to the plane of polarization of the ORS. This method allows one to exclude from the optical setup expensive optical elements (for example, quarter-wave plates) and simplify the design of the sensor / measuring device. In the course of experimental studies it was found that in this way it is possible to reduce the polarization distortion from the initial 17 dB to 1.6 dB.

399-405

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

The modeling of the illuminance distribution in the detection plane of an optical scheme composed of an objective and an Offner spectrometer is conducted. We calculate the illuminance distribution in the detection plane of the hyperspectrometer in the geometric optics approximation. The calculations use models of the atmospheric brightness, earth's surface irradiance, and the spectral transmission of the atmosphere.

412-421

Authors: O.O. Evsutin, A.A. Shelupanov, R.V. Meshcheryakov, D.O. Bondarenko

In the paper, we consider a particular direction of digital steganography — information embedding into the compressed JPEG images. A scheme of information embedding based on procedures of DCT-coefficients replacement is introduced. Variants of the scheme algorithmic implementation are offered and investigated. A genetic algorithm is used for the improvement of the embedding quality. The main result of the investigation is a steganographic algorithm of information embedding into the compressed JPEG images. This algorithm utilizes an unstable region of embedding at the level of one block of DCT-coefficients. The choice of an optimum region of embedding is performed by the genetic algorithm.

431-440

Authors: A.A. Afanasyev, A.V. Zamyatin

We consider most widely used practical methods for land cover change detection based on remote data sensing. Based on these methods, approaches to constructing hybrid methods are proposed. Results of the experimental study of the proposed methods in the presence of noise of various types and intensities are discussed. Based on the results of the experiments, hybrid methods that allow one to achieve a better quality in automatic change detection when compared to the known methods are determined.

453-460

Authors: A.S. Shirokanev, D.V. Kirsh, A.V. Kupriyanov

In the analysis of a crystalline substance, the problem of crystal lattice parameter identification is of a great interest. However, the existing methods for solving this problem, such as the Bravais cell parameters estimation method and Wigner-Seitz cell volume estimation method, do not provide the required level of accuracy. Aiming to address the problem of low identification accuracy, the paper proposes an algorithm for crystal lattice parameter identification based on the gradient steepest descent method. The study of the feasibility of the structure parameter identification is carried out using a large set of distorted lattices. The results obtained show a significant increase in the identification accuracy in comparison with the above-mentioned parameter identification methods.