Computer Optics

372-376

Authors: N.V. Golovastikov, D.A. Bykov, L.L. Doskolovich

The diffraction of a 2D optical beam upon a multilayer Bragg structure is considered. It is shown that phase-shifted Bragg grating can perform spatial integration in transmission of a 2D incident beam in the vicinity of the angular frequency associated with the excitation of a quasi-guided mode confined to the defect layer. The integration is fulfilled with an exponential weight function which fades away as the quality factor of the resonance increases. Beam propagation simulation results are in close agreement with provided theoretical description.

380-385

Authors: E.S. Kozlova, V.V. Kotlyar

Truncated ellipsoid which all parallel incident rays collects on it’s flat surface is designed. Simulation by (FD)2TD method of focusing of femtosecond pulse (duration 1.24 fs and the carrier wavelength λ = 532 nm) by a silica truncated microellipsoid with smaller cross-sectional diameter of 1.16 mm showed that the ellipsoid gives an elliptical focus spot with a smaller diameter FWHM = 0,38 λ. At the same time the pulse duration at the focus of a few percent smaller than the duration of the incoming pulse.

393-396

Authors: D.A. Kozlov , V.V. Kotlyar

In this paper we provide a numerically obtained result for analytical solution for the problem of monochromatic nonparaxial Gaussian beam diffraction by uniform dielectric cylinder, which yields a focal spot outside the cylinder with linear sizes twice less than the diffraction limit in the free space in case of cylinder radius comparable with the wavelength. Although the radius of cylinder is only two times larger than the wavelength, the produced intensity in focal spot is 48 times larger than the maximal intensity of incident Gaussian beam. Two percent deviation from the resonant radius (for a fixed wavelength) causes the focal spot increase in half, and the resulted intensity in focal spot drop to value of 12 times greater than the incident beam intensity. Obtained solution corresponds to the growth of the Bessel function of order 18 coefficient in E-field amplitude Bessel series expansion.

402-411

Authors: A.V. Ustinov, S.N. Khonina

In previous studies we shown on the basis of the geometrical-optical analysis that the fracxicon (generalized optical element of the parabolic lens and the linear axicon) formally produces an infinitely large value of the intensity on the optical axis. Within frame of the paraxial wave model this caustic effect was not found. In this paper, we consider plane wave diffraction on the fracxicon in nonparaxial wave model and we show that at high numerical aperture the fracxicon with an exponent close to 3/2, is actually analogue of the hyperbolic lens optimally focusing incident beam.

418-424

Authors: G.I. Greisukh, E.G. Ezhov, S.V. Kazin, Z.A. Sidyakina, S.A. Stepanov

Adverse impact of the diffraction orders on visually assess the quality of the image formed by refractive-diffractive optical system is investigated. It is shown that if the microstructure of diffractive lenses used in the optical system has a saw-tooth profile and brightness variations in the photographed scenes that are not extreme, the adverse diffraction orders practically not reduce of the system's frequency-contrast characteristic, and the halo does not have any significant negative impact for visual perception of the image.

435-442

Authors: S.V. Kravchenko, M.A. Moiseev, L.L. Doskolovich

New optimization method for design of refractive optical elements with two free-form surfaces is presented. Algorithm of design consists of two parts: generation of initial approximation and the further optimization of outer surface parameters from condition of producing prescribed illuminance distribution. As an example the optical element generating uniformly illuminated rectangular region with angular sizes 60° × 40° with extended 1x1 mm Lambertian light source is computed. The light efficacy of optical element is about 88,5% and the relative root-mean-square error of generated illuminance distribution is less than 8,5 %.

449-455

Authors: K.V. Borisova, M.A. Moiseev, L.L. Doskolovich, E.S. Andreev

A numerical-analytical approach is proposed for designing reflective surface producing prescribed irradiance distribution on the curve with specified shape. Method consists of two steps: computation of eikonal function on curve and reconstruction of the reflective surface using precomputed eikonal function. Reflective surface generating spiral line and module of backlight system for displays are designed. The simulation results demonstrate high-quality of the proposed method: light efficiency of backlight system is 86.5 % and uniformity of illuminance distribution is 93 %.

463-468

Authors: R.V. Skidanov, S.V. Ganchevskaya

Was considered the formation of Bessel beams by vortex axicons with different topological charges patterns. Presented the results of mathematical simulation and experiments.

476-481

Authors: V.G. Volostnikov, S.A. Kishkin, S.P. Kotova

The paper brings forward a theoretical study of the usability of the mathematical apparatus of spiral beams for problems of the contour images identification. The estimation of the approach offered is given in the light of its advantages and shortcomings, numerical simulation results are offered and the method applications aspects are analyzed in the context of actual practical tasks.

489-493

Authors: A.M. Belov, V.V. Myasnikov

The paper presents a method of atmospheric correction of spaceborne hyperspectral images. The method based on approximate solution of MODTRAN transmittance equation using simultaneous analysis of spaceborne and airborne hyperspectral images.

503-510

Authors: D.A. Zherdev, N.L. Kazanskiy, V.A. Fursov

In the work study the object recognition problem by the radar signatures of scattering reflected electromagnetic radiation. As template we use diagrams that made by computing the scattering field of 3d object models. The conjugation index with so-called support subspace that formed by attribute vectors of recognition class used in recognition as metric distance. Recognition quality in depending upon the dimension of support subspaces is studied. In work give comparison of result obtained by support vector machine and the compute correlation index with average class vector.

521-528

Authors: Y.Y. Ogorodnikov, R.T. Faizullin

The paper presents two heuristic methods of recognizing zero bits satisfiability problem. The first is based on the reduction of the satisfiability problem to an equivalent problem of minimizing a continuous smooth function by method of successive approximations, extended by changing the order of calculation of variables. Another way is to reduce to a system of linear algebraic equations with symmetric diagonally dominant matrix.

539-549

Authors: A.A. Agafonov, V.V. Myasnikov

A problem of traffic flow analysis and prediction in city transport network is considered in this paper. The proposed algorithm uses GPS / GLONASS data of public transport location as input. Projecting this information on a transport network graph, as well as using additional filtering, we estimate traffic flow parameters. These parameters are used for short-term (up to 1 hour) prediction of road conditions in the city transport network. There is proposed a new method which consists of several steps to construct prediction. First, the transport graph is divided into a number of subgraphs by a territorial basis. Second, we use a dimension reduction method based on principal components analysis to describe the spatio-temporal distribution of traffic flow condition in the subgraphs. Third, an elementary prediction for each of the subgraphs is formed using the potential functions method with the measure of the subgraphs descriptions closeness introduced by analogy with bilateral filtering and support vector machine. Fourth, the additional elementary prediction is calculated using the known scalar and vector Box–Jenkins time series prediction models. Fifth, we construct the result prediction for each of the subgraphs using an adaptive linear composition of elementary predictions. At last, the traffic flow parameters are calculated as a linear combination of predictions for subgraphs of the city transport network. We have also made experimental investigations of transport network in Samara to evaluate the prediction accuracy of the proposed algorithm. The advantages of the proposed solution in comparison with existing ones are provided.

555-563

Authors: A.V. Verichev, V.A. Fedoseev

The paper presents a digital watermarking scheme robust to geometric distortions of an image. The proposed scheme is based on Delaunay tessellation built on a set of feature points. Various feature points extraction methods are outlined and the best one for the watermarking scheme is chosen. Embedding and extracting algorithms are presented, emphasize being on the procedures of perceptual masking of the embedded watermark according to the human visual system. Numerical experiments are performed to demonstrate robustness of the proposed watermarking scheme to a wide range of geometric distortions.

574-579

Authors: D.G. Asatryan, V.V. Kurkchiyan, L.R. Kharatyan

In this paper, novel method for texture analysis and classification based on using image structural properties is proposed. It is known that the Human Visual System successfully perceives an image content by visualized collection of existing edges. In this paper, we propose to use the collection of gradient magnitudes as the characteristics of the structure of an image. Gradient magnitude is assumed to be a random variable with two-parameter Weibull distribution, and as a characteristic of the proximity of the two images we use a special measure of proximity of the parameter estimates of the corresponding distributions. Classification is made by method of comparison with the etalon using the database of the University of Heidelberg (Germany) which contains 10 texture classes. As an etalon is used the set of average values of the parameters estimates of the Weibull distribution, calculated by the magnitude gradients of training set of texture, and comparison is performed using the proposed proximity measure. The analysis revealed two virtually indistinguishable classes, and for the remaining eight classes it is shown that the classification error on the average is about 18%.