Computer Optics

135-140

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

It is shown numerically that using planar gradient microlenses, the coherent radiation can be focused in a narrow line of width λ/38 and length λ/5.5. The efficiency of focusing is 22%. A slitted photonic-crystal lens retains the properties of sharp focusing of light characteristic of a gradient lens. Substitution of the gradient lens by a photonic-crystal analogue synthesized in a silicon was found not to degrade the characteristics of the lens substantially. In this case, we observed a reduction of side lobes near the focal spot and a 30.2% increase of the focusing efficiency.

147-151

Authors: V.G.Volostnikov

An asymptotic behavior of orbital angular momentum (OAM) for the light field as superposition of Hermite-Gaussian modes is considered. An analytical formula for the OAM of such fields is obtained. For a three- and four mode superposition it was found that their OAM can be larger than the maximum index in the superposition while the structural stability of the light field is retained.

158-163

Authors: E.N. Vorontsov, N.N. Losevsky, D.V. Prokopova, E.V. Razueva, S.A Samagin

On the basis of optical properties of spiral beams, various light fields whose intensity pattern rotates during the field propagation have been investigated. A dependence between the parameters of the illuminating beam and the quality of the generated light fields is discussed. The light fields have been formed using a liquid-crystal spatial phase modulator HOLOEYE HEO-1080P. The results of the experiments are in good agreement with numerical simulations.

173-178

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

We study the possibility of creating a purely diffractive focusing doublet consisting of two components that are spaced apart. This doublet is able to focus light from three monochromatic sources with different wavelengths into the same focal spot. We analyze the characteristics of the designed doublet. Polychromatic focal distributions generated by the developed system are numerically calculated.

188-193

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

Ways and methods of modeling and calculating a holographic combiner for a virtual display are presented. On the one hand, they allow Denisyuk holograms with high diffraction efficiency independent of the field angle to be generated. On the other hand, they allow the advantages of the holographic combiner when compared with a multilayer dielectric mirror to be maximally realized. Optimization and search of the design parameters of elements of an optical setup for generating an aspherical wavefront for recording a Denisyuk hologram are based on ray tracing. These processes are greatly facilitated by the use of an intermediate model in the form of a thin transparency for phase delay. The phase delay of this transparency, the mirror geometry of the optical setup that forms the aspherical wavefront for recording the hologram, and the actual model of Denisyuk hologram in this article are described in the form adopted in the Zemax environment for surfaces such as Binary1, Extended polynomial and Optically Fabricated Hologram.

203-214

Authors: N.L. Kazanskiy, I.S. Stepanenko, A.I. Khaimovich, S.V. Kravchenko, E.V. Byzov, M.A. Moiseev

A technique for controlling and optimizing injection molding parameters by numerical simulation is proposed. Using this method for an optical element designed for roadway lighting, multilens molding quality criteria have been defined. Optimal parameters for lens manufacturing have been determined. Based on these parameters, a polycarbonate multilens has been made with an absolute tolerance equal to 0.01 mm.

225-231

Authors: M.V. Gashnikov

Parameterization of the nonlinear Greham predictor is performed for a digital image compression method based on the differential pulse code modulation. The predictor automatically selects different methods for calculating each pixel in the image based on the availability and intensity of that pixel contour. A fast learning procedure that optimizes the prediction parameters is performed before the actual compression. In the course of optimization, the minimum sum of absolute values of prediction errors is provided. For this purpose, a recursive procedure is used, whose computational complexity is independent of the image size. The estimation of the computational complexity of the proposed predictor is conducted. To study the predictors computational experiments are carried out on real images. A gain the proposed predictor offers in terms of the root mean square error when compared with the prototypes is demonstrated. In addition, a gain that the compression method based on the differential pulse code modulation with the proposed predictor has over the JPEG compression method in terms of the maximum error is demonstrated.

240-248

Authors: I.A. Bratchenko, M.V. Alonova, O.O. Myakinin, A.A. Moryatov, S.V. Kozlov, V.P. Zakharov

The paper presents the analysis of hyperspectral images for human skin cancer diagnosis. The hyperspectral imaging data contained backscattered spectra of normal skin and malignant skin tumors. The analysis of hyperspectral images provided the information about the shape and intensity of hemoglobin and melanin spectral lines for the differentiation of malignant pigmented skin neoplasms.

258-265

Authors: A.I. Efimov, A.I. Novikov

We propose a multistage algorithm for constructing a projective transformation based on arbitrary sets of keypoint pairs, with the sets containing more than four keypoint pairs. In the course of calculation of a homography matrix, unsuccessful keypoint pairs are detected and rejected. Experimental results on image superimposition using projective transformations for homogeneous and heterogeneous images are presented. Methods for assessing the quality of image superimposition, which include the local and integral estimates of the superimposition quality, are proposed.

275-283

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

A reliable shortest path problem in time-dependent stochastic networks is considered in this paper. We develop and research a method for reliable routing that uses actual and forecast information of traffic flow parameters. We compare the performance of the proposed algorithm with that of a well-known algorithm on a real traffic network in the city of Samara, Russia. On the basis of computing experiments it is shown that while being a bit more computationally challenging, the proposed method increases the possibility of successfully solving the shortest path problem in a time-dependent stochastic network.

294-300

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

A new public dataset of traffic sign images is presented. The dataset is intended for training and testing the algorithms of traffic sign recognition. We describe the dataset structure and guidelines for working with the dataset, comparing it with the previously published traffic sign datasets. The evaluation of modern detection and classification algorithms conducted using the proposed dataset has shown that existing methods of recognition of a wide class of traffic signs do not achieve the accuracy and completeness required for a number of applications.