Computer Optics

727-735

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

A two-parameter family of astigmatic elliptical Gaussian (AEG) optical vortices is found, which are free space modes up to scale and rotation. We calculate the total normalized orbital angular momentum of AEG vortices, which can be integer, fractional and zero, and which is equal to the algebraic sum of two terms corresponding to the contribution of the vortex and astigmatic components of the light field. In any transverse plane, such a beam has an isolated n-fold degenerate intensity null on the optical axis (an optical vortex) embedded into an elliptical Gaussian beam. In addition to the quadratic elliptical phase, the beam has a phase of a cylindrical lens rotated by an angle of 45 degrees relative to the principal axes of the Gaussian beam intensity ellipse.

744-750

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

Using Richards-Wolf formulae it is shown that a tightly focused azimuthally-radially polarized m-th order laser beam with an arbitrary apodization function produces a reverse energy flow in the focal plane (m=2). If m=3, the reverse energy flow on the axis is equal to zero, increasing in the axis vicinity as the square of the distance to the axis. The azimuthally-radially polarized beam of the m-th order is an example of a polarization vortex. Previously, the reverse energy flow in the focus was obtained only for circularly polarized vortex beams with the topological charge m. Using the FDTD method and the Richards-Wolf formulae, we show numerically that in the focus of a zone plate such laser beams produce regions where the Poynting vector is opposite to the direction of the beam propagation.

758-763

Authors: Nesterenko D.V., Kolesnikova M.D., Lyubarskaya A.V

In this work, technologies of analog optical computing for image edge detection using flat interfaces between dielectrics are studied both theoretically and experimentally. The feasibility of analog differentiation and edge detection by using the Brewster effect for polarized light sources is demonstrated. The efficiency of the analog image processing is investigated using a variety of amplitude and phase masks.

772-778

Authors: Doskolovich L.L., Andreeva K.V., Bykov D.A

Design of an axisymmetric refracting optical element to transform an incident beam into an output beam with the prescribed illuminance distribution and prescribed wavefront is considered. The wavefront of the output beam is represented by the eikonal function defined in some plane behind the optical element. The computation of the optical element surface is reduced to the solution of two explicit ordinary differential equations of the first order. As examples, we consider the design of two optical elements to transform a spherical beam from a point Lambert light source into a beam with the uniform illuminance and plane wavefront and a beam with the complex wavefront to focus into an on-axis line.

786-799

Authors: Vinogradova I.L., Meshkov I.K., Grakhova E.P., Sultanov A.Kh., Bagmanov V.Kh., Voronkova A.V., Gizatulin A.R

Design principles are proposed for a secure subterahertz RoF segment providing independent optical modulation by radiochannel frequency characteristics and a phased antenna array beamsteering parameter. A design scheme of the RoF segment for the W-range is proposed. The results obtained include co-transmission of two modes (one of which is polarized), radio channel frequency properties control, orbital angular momentum signal shaping, co-transmission of a modulated optical signal and a polarized signal and orbital angular momentum signal. Simulation is carried out for signals with a given spin-orbit state based on a Hamiltonian approach. Results of a phase-amplitude filter calculation are presented.

807-815

Authors: Panyaev I.S., Sannikov D.G

Guiding properties of an optical waveguide based on a layered metamaterial formed by layers of iron-yttrium garnet and aluminum-yttrium garnet, magnetized to saturation are considered. Dispersion equations for the waveguide TE and TM modes in the structure were obtained using the approximation of an effective medium and solving the boundary problem (electromagnetic method), and also by means of a 4×4 matrix method. Dispersion spectra of the propagation constant dependence on the cyclic frequency ω(β) for different types of structures are found, localization coefficients of the orthogonal modes in the guiding layer are also derived and their comparative analysis is carried out. The advantages of the approximate electromagnetic method are shown in comparison with the exact 4x4 matrix method. The results of the work can find an application in developing new integrated optical devices for optical signal processing based on layered metamaterials.

822-828

Authors: Dmitriev E.A., Myasnikov V.V

The paper presents an analysis of various approaches to constructing descriptions for the gradient fields of digital images. The analyzed approaches are based on the well-known methods for data dimensionality reduction, such as Principal (PCA) and Independent (ICA) Component Analysis, Linear Discriminant Analysis (LDA). We apply these methods not to the original image, represented as a twodimensional field of brightness (a halftone image), but to its secondary representation in the form of a two-dimensional gradient field, that is, a complex-valued image. In this case, approaches based on using both the entire gradient field and only its phase component are considered. In addition, two independent ways of forming the final description of the original object are considered: using expansion coefficients of the gradient field in a derived basis and using an original authors' design that is called model-oriented descriptors. With the latter, the number of real coefficients used in the description of the original object can be halved. The studies are conducted via solving a face recognition problem. The effectiveness of the analyzed methods is demonstrated by applying them to images from Extended Yale Face Database B. The comparison is made using a nearest neighbor's classifier.

838-845

Authors: Thang P.C., Kopylov A.V

We consider here image denoising procedures, based on computationally effective tree-serial parametric dynamic programming procedures, different representations of an image lattice by the set of acyclic graphs and non-convex regularization of a new type which allows to flexibly set a priori preferences. Experimental results in image denoising, as well as comparison with related methods, are provided. A new extended version of multi quadratic dynamic programming procedures for image denoising, proposed here, shows an improved accuracy for images of a different type.

855-863

Authors: Belov A.M., Denisova A.Y

In the article we propose a spatial and spectral super-resolution algorithm for a set of multichannel images obtained by various Earth remote sensing detectors. We regard the result of the algorithm as a model of an ideal data source, which has a better accuracy of the observed terrain representation than each of the input images having lower spatial and spectral resolution. The proposed algorithm utilizes a method of gradient descent and applies a refined model of image observation, including both spectral and spatial down-sampling and up-sampling. The article describes an experimental study of the proposed algorithm and a comparison of the quality of its work with bilinear interpolation of low-resolution images. The practical application of the proposed algorithm consists in the joint processing of remote sensing data of various levels, which makes it possible to erase the boundaries that arise from the design differences of imaging sensors.

877-884

Authors: Podlipnov V.V., Shchedrin V.N., Babichev A.N., Vasilyev S.M., Blank V.A

The possibility of humidity determination based on the use of spectral distributions in the wavelength range of up to 1 µm is analyzed. We discuss the use of an imaging hyperspectrometer for precision farming. A field experiment to determine the soil moisture index under the vegetation cover is described. A procedure of precise calibration of the hyperspectrometer based on the use of a tunable laser is described. We show the possibility of the practical determination of humidity based on the use of spectra in the wavelength range of up to 1 µm.

898-903

Authors: Ruchay A.N., Dorofeev K.A., Kolpakov V.I

In this paper, we estimate the accuracy of 3D object reconstruction using multiple Kinect sensors. First, we discuss the calibration of multiple Kinect sensors, and provide an analysis of the accuracy and resolution of the depth data. Next, the precision of coordinate mapping between sensors data for registration of depth and color images is evaluated. We test a proposed system for 3D object reconstruction with four Kinect V2 sensors and present reconstruction accuracy results. Experiments and computer simulation are carried out using Matlab and Kinect V2.

912-920

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

Autonomous vehicle development is one of many trends that will affect future transport demands and planning needs. Autonomous vehicles management as a part of an intelligent transportation system could significantly reduce traffic jams and decrease the overall travel time. In this work, we investigate a route reservation architecture to manage road traffic within an urban area. The routing architecture decomposes road segments into time and spatial slots for every vehicle, it makes the reservation of appropriate slots on the road segments in the selected route. This approach allows one to predict the traffic in the road network and find the shortest path more precisely. We propose that a rerouting procedure should be utilized to improve the quality of the routing approach. We consider several speed-density relations to estimate the vehicle speed based on a road segment reservation state. The experimental study of the routing architecture is conducted using microscopic traffic simulation in SUMO package.