Computer Optics

366-374

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

Topological charges (TC) of a superposition of two Laguerre-Gauss (LG) beams (0,m) and (0,n) symmetrically shifted from the optical axis are found in this work. It is shown that if m=n, then the TC of the superposition is equal to n. That is, two identical off-axis LG beams have the net TC as that of a single LG beam. If m

381-387

Authors: S.S. Stafeev, V.D. Zaitsev, V.V. Kotlyar

We consider sharp focusing of a linearly polarized light beam. Using the Richards-Wolf formalism, we show that before and after the focal plane there are cross-section regions in which the polarization is circular (elliptical). When passing through the focal plane, the direction of rotation of the polarization vector is reversed. If before the focus the light is left-hand circular polarized at a definite region of the beam cross-section, then exactly at the focus the polarization becomes linear at this cross-section region, before becoming right circular polarized after the focus at this region. This effect allows linearly polarized light to be used to rotate weakly absorbing dielectric microparticles around their center of mass.

395-405

Authors: I.M. Sizova, D.B. Stavrovskii

A theoretical investigation has been carried out of the evolution of a monochromatic laser beam profile after the beam exit from an apodizer. The optical scheme of the apodizer consists of a circular serrated aperture with a narrow opaque corrective ring and a spatial filter based on the Kepler telescope with a pinhole. Characteristic parameters of the apodizer have been found, which allows one to use the corrective ring for the improvement of the apodized beam profile quality and reduce the beam diffraction distortion at beam propagation over distances corresponding to the Fresnel numbers NF~5...2.

415-421

Authors: V.V. Podlipnov, D.A. Bykov, D.V. Nesterenko

CdTe thin films have been deposited by thermal evaporation on heated glass substrates. Structural properties of the CdTe thin films were studied by scanning electron microscopy and Raman spectroscopy. Optical properties were examined by ellipsometry and Fourier spectroscopy. We revealed the low absorption of the synthesized thin films in the infrared (IR) region. We investigated the sensing capability of metal / dielectric / dielectric structures based on a CdTe waveguide layer and gold thick film. The reflectivity spectra of the structures with the water, ethanol, and isopropanol as sensing media exhibit resonance line shapes. The positions of the resonances correspond to those of local maximal values of the solvents absorption. The obtained results can be used for developing the applications of optical resonances in the IR region.

429-435

Authors: A. Sheshkus, A. Chirvonaya, V.L. Arlazarov

In this paper, we study the problem of feature points description in the context of document analysis and template matching. Our study shows that specific training data is required for the task especially if we are to train a lightweight neural network that will be usable on devices with limited computational resources. In this paper, we construct and provide a dataset of photo and synthetically generated images and a method of training patches generation from it. We prove the effectiveness of this data by training a lightweight neural network and show how it performs in both general and documents patches matching. The training was done on the provided dataset in comparison with HPatches training dataset and for the testing, we solve HPatches testing framework tasks and template matching task on two publicly available datasets with various documents pictured on complex backgrounds: MIDV-500 and MIDV-2019.

455-464

Authors: A.V. Shonenkov, D.K. Karachev, M.Y. Novopoltsev, M.S. Potanin, D.V. Dimitrov, A.V. Chertok

We introduce two data augmentation techniques, which, used with a Resnet-BiLSTM-CTC network, significantly reduce Word Error Rate and Character Error Rate beyond best-reported results on handwriting text recognition tasks. We apply a novel augmentation that simulates strikethrough text (HandWritten Blots) and a handwritten text generation method based on printed text (StackMix), which proved to be very effective in handwriting text recognition tasks. StackMix uses weakly-supervised framework to get character boundaries. Because these data augmentation techniques are independent of the network used, they could also be applied to enhance the performance of other networks and approaches to handwriting text recognition. Extensive experiments on ten handwritten text datasets show that HandWritten Blots augmentation and StackMix significantly improve the quality of handwriting text recognition models.

473-478

Authors: V.A. Komarov, A.A. Pavlov

A problem of determining the fiber volume fraction in fiber-reinforced strands of fabric-based laminated composites is considered. As a source of information about the structure of the material, digital micrographs of the ground surface of the cross-sections of the composites are used. Methods and features of the analysis of raster microscopic images of heterogeneous material associated with variable pixel brightness and blurring of the "fiber-binder" boundaries are discussed. To make the image processing less labor-intensive and more objective, a special autoencoder is proposed and built. The study of the structure of a typical structural carbon fiber-reinforced plastic is illustrated by an end-to-end demonstration example. A significant acceleration of the image processing process using the convolutional autoencoder and a good agreement of the results with a careful manual analysis are shown.

483-491

Authors: S.V. Pavlov, A.V. Sokolova, O.I. Khristodulo

In this article, we consider an approach to integrating geoinformation technologies and digital image processing methods aimed at increasing the efficiency of computer technologies in controlling complex distributed systems (CDS) in emergency situations. The analysis is conducted using an example of the activity of oil pipeline transport enterprises, including pipelines, oil pumping stations, administrative, repair and emergency response units. The novelty of the proposed version of integration of geoinformation technologies and digital image processing consists in the application of a set-theoretic approach to a uniform formal description of various types of spatial data, digital images and their interrelationships necessary for constructing three-dimensional models of production facilities of CDS. This has allowed criteria, composition and structure of these 3D models to be defined using different levels of detail of the object models in order to reduce the computational load and speed up the 3D visualization of objects of CDS. These are necessary to support the decision-making when responding to certain types of emergency situations. The advantage of the proposed approach is that it increases the efficiency of decision-making support in countering some emergencies, which, among others, is achieved through the use of three-dimensional visualization of technological and operational (obtained in the event of an accident) information about the production facilities of the CDS, whereas the quality and fullness of the optimized 3D model directly affect the decisions made in response to the emergencies. The developed methods and algorithms have been practically implemented when building 3D geoinformation models.

506-512

Authors: B.S. Mandrikova

A method for analyzing data of complex structure based on combining a wavelet transform and neural networks Autoencoder is proposed. The method allows you to research the data structure, detect abnormal changes of various shapes and durations, and suppress noise. The efficiency of the method is shown on the example of data from a network of neutron monitor stations. Neutron monitor data determine the intensity of secondary cosmic rays and are one of the key factors in space weather. The numerical implementation of the method allows it to be applied on-line, which is of interest in problems of analyzing environmental data and detecting catastrophic events.