Computer Optics

765-771

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

We have considered circularly polarized vectorial Hankel beams. These beams are a generalization of the spherical wave with embedded optical vortex. Explicit analytical expressions have been derived for all six components of the electric and magnetic vectors of the electromagnetic field. These expressions are an exact solution of Maxwell's equations. We have shown the difference in free space propagation for Hankel beams with left and right circular polarization. For the far field, we also obtained expressions for the components of the Umov-Poynting vector and angular momentum

781-792

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

It It is shown both theoretically and experimentally that if a cylindrical lens is placed into a laser beam, having an optical vortex with integer topological charge n and on-axis intensity null, then at the double focal distance behind the lens, the n-fold degenerate intensity null is split into n isolated intensity nulls. These intensity nulls lie on a straight line in the transverse plane at an angle of + 45 or – 45 degrees to the axis of the cylindrical lens, depending on the vortex helicity direction (i.e. sign of the topological charge). Experiments show that such a method can be used to determine higher-order topological charges up to n = 100.

802-809

Authors: D.S. Lushnikov, A.Y. Zherdev, V.V. Markin, S.B. Odinokov, A.V. Smirnov

In this paper, dependencies of the angular and spectral selectivity on the incidence angle of the reference beam in a scheme for obtaining reflection and transmission holograms are obtained and analyzed. It is shown that for obtaining color holographic stereograms a scheme for obtaining transmission holograms is more suitable. While the angular selectivity of reflection and transmission color holograms is the same, the spectral selectivity of the reflection hologram is much higher at all wavelengths of recording. A method and equipment for one-step digital recording of color full-parallax holographic stereograms with rasterless image are developed. Samples of color fullparallax security holographic stereograms with a “flip-flop” effect in the image were obtained. The quality of the reconstructed image verifies high spectral selectivity for this type of holograms.

818-829

Authors: A.G. Poleshchuk, V.P. Korolkov, R.K. Nasyrov, V.N. Khomutov, A.S. Konchenko

Development of dedicated methods for nondestructive testing of microstructured optical elements is a prerequisite for the wide-scale manufacturing of diffractive, micro-optical and conformal elements. A variety of approaches to the characterization of diverse types of microstructured optical elements were developed at the laboratory of Diffractive Optics at IAE SB RAS. These methods are intended to test wavefront errors, etch depth and diffraction efficiency during and after the manufacturing of elements with binary and multi-level surface profile. The review of the developed techniques and measuring circuits given in the work takes into account specific features of the elements' parameters and application areas. Testing results for the manufactured elements are discussed.

837-843

Authors: N.A. Ivliev, V.A. Kolpakov, S.V. Krichevskiy

We present a method for determining the concentration of organic contaminants on the silica surface by using lateral force maps and surface topology images obtained with scanning probe microscopy. In this study, we optimized the scanning frequency to increase the contrast of images and facilitate interpretation of the data btained. We also proved experimentally that the sensitivity of the method reaches 10−11 g/cm2 .

850-854

Authors: D.S. Mikhailova

In a number of situations, the resolution of modern spectrometers may be not high enough. This communication describes the use of an auxiliary interferometer together with a diffraction spectrometer, thus enabling its resolution and sensitivity to be enhanced during spectroscopy of adsorbed molecular layers. In this way, the industrial device is turned into a combined diffractioninterference monochromator. Numerical calculations and experiments show that the resolution of the combined diffraction spectrometer can be enhanced by an order of magnitude. In addition, the described device is a tunable multi-beam interferometer, allowing scanning through the spectrum. Scanning is done by turning the multi-beam interferometer. The article provides experimental data on adjusting the interferometer by tilting it with respect to incident radiation. Provision is made for the adjustment of the device by using a piezo plate. The increased sensitivity of the combined device allows it to be used as a spectrum analyzer of adsorbed substances. The design of the attachment provides an easy-to-install fitting for the input of the substance under test.

863-870

Authors: M.A. Zavyalova

An experimental laser system for studying the processes of micro– and nanostructure direct formation in a silica glass by picosecond laser pulses is described. A method of ablation monitoring based on the Shack-Hartmann wavefront sensor is proposed. Ablation craters on the surface of the silica glass varying in depth from 23 ± 4 to 144 ± 18 nm with good edge quality with the power density varying from 0.57 × 1012 to 31 × 1012 W/cm2, respectively, are synthesized. Higher-intensity modes of laser processing lead to the formation of cracks and chips on the surface of the material, with lower-intensity processing leading to the appearance of melting edges. The obtained structures are characterized using an atomic force microscope. The ablation rate of the silica glass is established.

878-886

Authors: V.A. Fursov

A problem of the restoration of defocused images is considered. For this purpose, we construct an FIR-filter by identifying the model from a special class of parameters with use of test images. The model of impulse response is defined in a class of univariate functions, which approximate the required frequency response in the radial direction. Samples of the twodimensional impulse response are defined by discretization and the subsequent sample normalization. The approximation function class is defined so as to amplify low and suppress high spectrum frequencies. Important advantages of the method are high-quality image restoration and fast identification of filter's model due to the fact that the approximating function is determined by a small number of unknown parameters. In this article realization examples are given. These examples show the possibility of achieving the higher-quality restoration in comparison with the Wiener filter from the open-source image processing library OpenCV.

895-903

Authors: A.V. Umnov, A.S. Krylov

In this paper we suggest an algorithm for ringing suppression based on a sparse representation method. As one of its steps, the suggested method includes image deblurring based on the Wiener-Hunt deconvolution algorithm. The ringing suppression algorithm uses the signals' mutual coherence and sparsities analysis when dealing with the ringing effect based on the sparse representation method. We also analyze the mutual coherence and sparsities for blurred images and images with white Gaussian noise.

911-918

Authors: A.V. Akimov , A.A. Sirota

The paper describes mathematical models and algorithms of warping grid functions with discrete parameters. For images, three warping models, applied to the generation of extra training data to build face recognition algorithms, are examined: the one based on harmonic functions, the one based on offsetting user-specified control point coordinates, and the one based on the computation of the optical flow between entropy-filtered images. For the training sets, both initial and those synthetically generated using the above three models, learning of face detection algorithms based on the ViolaJones framework was performed and corresponding detection rates were compared. It is shown that this approach is applicable for synthetic data generation when training image recognition algorithms for recognition of objects characterized by inherent structure.

929-938

Authors: N.S. Vorobiova, V.V. Sergeyev, A.V.Chernov

The paper deals with the development of information technology for early crop identification in the region of interest by using satellite images. With the early identification being performed in the first half of the growing season, it is characterized by the lack of ground-based and space-based data to configure recognition algorithms. The proposed technology allows one to generate a training dataset by using information from the past years and then use it for crop recognition for the current year. The technology consists of two stages. At the first stage, models of time series, crops and agroseasons are built using data from the past years. At the second stage, data of the current year are processed. First, a suitable model of agro-season, which is close to the development of crops in the current year, is selected by using a tiny set of control fields with known crops. Next, a training dataset is generated based on the characteristics of the agro-season model and the recognition of crops in the current season is performed. The paper assesses the quality of recognition offered by the proposed information technology and the possibility of its application in a particular region. Data collected for the years 2011 -2015 in the Samara Region are used for the experimental research.

947-957

Authors: A.A. Morozov, O.S. Sushkova

Object-oriented logical means for a real-time analysis of video were developed. The software includes a translator of the Actor Prolog object-oriented logic language to Java, an open source Java library that contains built-in classes of Actor Prolog, and a programming environment of the Actor Prolog language. An example of using the software for intelligent video monitoring of abnormal behavior in people is considered. Object-oriented means of the Actor Prolog language make it possible to divide a logic program into several parallel processes corresponding to various stages of the video processing. The translation of logic programs to Java provides reliability, portability, and openness of the intelligent video surveillance programs.

968-971

Authors: R.V. Skidanov, V.A. Blank

We considered the feasibility of using a dual-range diffraction grating on the convex mirror in an imaging hyperspectrometer based on the Offner scheme. We conducted modeling in Zemax software. It is shown that the use of a dual-range grating allows one to use the hyperspectrometer based on the Offner scheme in two spectral ranges: the visible and mid-infrared.