Computer Optics

534-541

Authors: Akimov A. A., Guzairov S. A., Ivakhnik V. V

The influence of feedback for both signal and object waves on the amplitude reflection coefficient of a four-wave radiation converter on thermal nonlinearity has been considered. The dependences of the reflection coefficient of a four-wave converter on the parameters of a ring-type resonator, which provides the feedback, and the pump intensity have been obtained and analyzed. It was shown that the use of a ring-type resonator allows one to increase the reflection coefficient of a four-wave radiation converter on thermal nonlinearity by several times.

550-556

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

We study an optical “angular tractor” effect, at which the energy flow in the cross-section of a rotationally symmetric vortex laser beam with the positive/negative topological charge and left-/right-handed circular polarization rotates in different directions (clockwise and counterclockwise) at different distances from the beam center. This effect is shown to take place both for paraxial vortex beams and in the focus of an aplanatic system focusing a nonparaxial optical vortex. Dielectric microparticles placed in a third-order circularly polarized Bessel beam are experimentally demonstrated to move in the opposite directions (clockwise and counterclockwise).

568-573

Authors: Mingazov A. A., Bykov D. A., Doskolovich L. L. , Kazanskiy N. L

The problem of calculation of the light field eikonal defined on a certain surface from the condition of generating a prescribed irradiance distribution on another surface is formulated as a Monge-Kantorovich mass transportation problem. We show that the cost function in this mass transportation problem corresponds to the distance between a point on the initial surface (on which the eikonal function is defined) and a point on the target surface, where the prescribed irradiance distribution is to be generated. An analytical expression for the gradient of a “cost functional” describing the mass transportation problem is derived. It enables using gradient descent methods for the calculation of the eikonal function.

588-605

Authors: Kharitonov S. I., Volotovsky S. G., Khonina S. N

In this paper, explicit expressions for the momentum and angular momentum from the Noether's theorem (ab initio) are obtained. These expressions contain squared modules of the coefficients of a guided mode expansion, weighted by the phase singularity orders present. The expressions obtained are useful for quantizing the electromagnetic field in a waveguide.

614-619

Authors: Perminov N. S., Petrovnin K. V., Gerasimov K. I., Kirillov R. S., Latypov R. R., Sherstyukov O. N., Moiseev S. A

We study spectral properties of a cascaded multiresonator microwave quantum memory integrated into a waveguide-resonator system. On the basis of experimental data, we reconstruct the internal parameters of the circuit under study, give estimates of quantum efficiency, and show the possibility of achieving optimal conditions for its realization.

627-636

Authors: Batomunkuev Yu. Ts., Dianova A. A., Maganakova T. V

The paper presents and discusses the results of calculations of the radii of transverse fifth-, seventh- and ninth-order spherical aberrations in a multi-order on-axis HOE (holographic optical element), recorded using two divergent spherical waves. As examples, focusing transmission and reflection on-axis HOEs with relative apertures close to 1:1 in given infrared spectral ranges are considered. Analytical expressions are presented for calculating the minimum distance from the HOE to a polychromatic point source and to its image. We study in which way these distances change with increasing operating wavelength in the spectral range of interest. Examples of two different transmission HOEs with identical chromatic aberrations are presented in the atmospheric infrared windows in the ranges of 2.15–2.50 μm and 4.3–5.0 μm. It is pointed out that on the basis of these two HOEs, a dual-band holographic lens with working spectral ranges of 2.15–2.50 μm and 4.3–5.0 μm can be developed.

657-666

Authors: Hodashinsky I. A., Kostyuchenko E. Yu., Sarin K. S., Anfilofiev A. E., Bardamova M. B., Samsonov S. S., Filimonenko I. V

Dynamic signature verification is one of the most fast, intuitive, and cost effective tools for user authentication. Dynamic signature recognition uses multiple characteristics in the analysis of an individual’s handwriting. Dynamic characteristics include the velocity, acceleration, timing, pressure, and direction of the signature strokes, all analyzed in the x, y, and z directions. In this paper, the constant term and the first seven harmonics of the Fourier series expansion of the signature were used as features. The authentication systems development includes the following stages: preprocessing, feature selection, classification. Binary metaheuristic algorithms and deterministic algorithms are used to select attributes. The classification was carried out using a fuzzy classifier. The fuzzy classifiers parameters were tuned using continuous metaheuristic algorithms. The efficiency of the authentication system was verified on the author's database. The database contains 280 original variants of the signature of one author and 1281 variants of counterfeit signatures of seven authors. To assess the statistical significance of differences in the accuracy and error rates of the fuzzy classifiers formed by metaheuristic algorithms, the Mann-Whitney (-Wilcoxon) U-test to compare medians and the Kruskal-Wallis test were used.

679-687

Authors: Maksimov A. I., Gashnikov M. V

Algorithms of interpolation of multidimensional signals for differential compression are investigated. We propose an approach for constructing adaptive interpolators based on the automatic selection of an interpolating function at each point of the signal. The selection is made with the use of attributes calculated from the point’s local neighborhood. An adaptive multidimensional interpolator is developed with this approach. It automatically selects an interpolating function at each point of the signal, providing improved contour interpolation accuracy. The choice is made by a decision rule based on a local characteristic of distinctness and direction of the contour. The proposed interpolator is implemented for a three-dimensional case. The interpolator switches between six interpolating functions: an averaging function and functions that take into account contours of five directions. An experimental study of the proposed algorithm is carried out on threedimensional hyper spectral remote sensing data. The proposed interpolator allows increasing the efficiency of differential compression.

695-703

Authors: Efremova O. A., Kunakov Yu. N., Pavlov S. V., Sultanov A. Kh

We address a problem of the joint processing of digital maps of the earth surface and satellite imagery of flooded areas as part of the software intended to help authorities to respond to emergency situations. The problem of mapping flooded areas is solved based on the use of satellite images and GIS technologies. This paper describes an algorithm for mapping areas submerged by flooded rivers based on radar satellite images and analysis of characteristic relief features, allowing one to improve the accuracy of the image geolocation with a small number of reference points. The experimental studies demonstrate that using the algorithm proposed, the alignment accuracy of the river water surface obtained from a satellite image and from a digital topographic map has increased by 40%.

712-721

Authors: Shirokanev A. S., Kirsh D. V., Ilyasova N. Yu., Kupriyanov A. V

Diabetic retinopathy is one of the most frequent complications of diabetes, which leads to severe consequences, including rapid and irreversible vision loss. The laser coagulation procedure to treat diabetic retinopathy consists in applying a series of microburns to the fundus to deal with macular edema. The existing hardware/software packages are primarily based on the use of a predetermined pattern for coagulate arrangement. However, due to the complex form of edema and vascular system, this approach leads to an uneven arrangement. To solve the problem, we propose a new approach based on the application of sphere packing algorithms (circle packing in two-dimensional images) in the specified area of interest. Since one of the main requirements for the laser coagulation procedure is that it should have the minimum duration, a problem of the computational complexity of the developed algorithms arises. This requirement is completely ignored by the existing approaches, therefore the development of new high-performance coagulate arrangement algorithms is highly relevant. In the paper, we propose seven new algorithms for coagulate arrangement and provide a detailed analysis of key characteristics of the algorithms. The characteristics considered have made it possible to extract information relating to the algorithm properties. Regularity is determined by the median, asymmetry and the kurtosis; determinism is determined by the variance and the mean.