Abstract The possibility of the fabrication of film axicons with large focal lengths is shown experimentally. The fabrication technology includes vacuum deposition of layers of chalcogenide glass of variable thickness, which varies linearly depending on the substrate radius. Axicons with focal lengths up to 15 m are obtained.

Abstract Molecular bands OH (306.1 nm), CH (430.18 nm), H\({}_{2}\)O (714–980 nm), C\({}_{2}\) (515.55 nm), NH (336 nm), NO (358.26 nm) have been identified (the most intense edges are shown in parentheses) in the plasma radiation spectra inside the low-emission combustion chamber of a gas turbine engine. This allows the ratio of their intensities to be used for controlling the working parameters of

Abstract The features of far field diffraction phenomena on cylindrical (metal) objects of small diameters (0.01–0.5 mm) are investigated taking into account their reflective properties within the framework of the Kirchhoff–Fresnel scalar theory of light diffraction. The calculations used a screen-type cylinder model (of zero thickness). The reflected far field component was calculated by the stationary

Abstract Basing on the structural lighting method, we develop a contactless system of the alignment control for weapon barrels. We propose and design a construction of a compact optical sound using a diffraction optical element to expose the barrel bore. We provide processing algorithms for images obtained under the scanning of the barrel bore; then, using these algorithms, we restore the 3\(D\)-shape

Abstract Silicon photonics is the most important technological platform for creating a variety of functional optical elements, including promising types of optical sensors. Moreover, in recent years, 20% of all publications on silicon photonics are devoted to the development of various versions of optical sensors. Their advantage steams from the combination of high technical parameters with the possibility

Abstract The new experimental data on the dynamics of diffraction efficiency (DE) of superimposed volume reflection holograms with a grating period of \({\sim}\)250 nm is obtained at their simultaneous recording in the photopolymer material BAYFOL HX TP. The character and parameters of their interaction are established when exposure of one hologram is delayed relative to the other one. It is revealed

Abstract The article considers the possibility of constructing laser Doppler velocity vector meters based on a bichromatic source of spatially combined Gaussian or Bessel beams, the two-wave single-channel Bragg acousto-optic modulator with a ratio of ultrasonic wave frequencies equal to the ratio of the wave numbers of diffracted laser beams. The spatial, chromatic, and frequency structure of the

Abstract The possibility of determining deformations of large-sized objects by structured illumination is considered. The method is based on projection of sinusoidal fringe patterns on the surface of the object under study. Using the step-by-step phase shift allows one to distinguish information about the phase distribution reflecting the surface relief. Comparison of phase distributions before and

Abstract A method and physical and technical design of the laser heterodyne tomography of scattering properties of thick photosensitive materials (media) in the reflection mode are proposed. The method is based on the acoustooptic scanning of a test reflection grating recorded in the medium and on the layer-by-layer collinear heterodyne analysis of the scattered field. The formulas for estimating the

Abstract The influence of spatial inhomogeneity of the photoelectric characteristics of a matrix photodetector (PDD) on the quality of detection of small-sized objects in the image formed by it is considered. It is shown that in the conditions of spatially inhomogeneous natural noise of the PDD, the traditionally applied two-point correction is not optimal for subsequent matched image filtering performed

Abstract A single-frequency all-fiber thulium doped laser with distributed feedback is presented. The fiber Bragg grating with a phase shift, which is the cavity of the laser, is written in a highly-doped 36-mm segment of the thulium-doped fiber. The highest power of the single-frequency generation on the wavelength of 1919 nm reaches up to 80 mW at the power of the pumping radiation of 1.1 W. The

Abstract A brief survey of present-day achievements in quantum informatics is presented. Advantages of quantum computers are shown by an example of simplest quantum algorithms. Application of ultracold atoms for the implementation of quantum processors is considered.

Abstract We propose a method to control the multi-element mirror system of the telescope of the space observatory ‘‘Millimetron’’ under its tuning taking place after the opening on the orbit. For the preliminary control of the location of reflector elements, the laser rangefinder is used; for the final control, the optical method of the Foucault knife is used. We compute the optical scheme of the control

Abstract The methods based on processing video data have shown their efficiency in many areas of agriculture and forestry. Nevertheless, they are not enough accurate for classification of barely discernible objects and types of plants, which can be provided only using hyperspectral sensors. However, such devices by now were expensive and difficult in operation and were used mostly on satellites and

Abstract Using the experimental setup for poling film samples with capability of continuous monitoring of generation signal of second harmonic, the conditions of effective orientation of chromophore molecules based on polyfluoro-substituted triaryl pyrazoline and dicyan-substituted isophoron in micron films of polycarbonate are determined. The second harmonic is excited with the pulse Nd:YAG laser

Abstract A method for vertical adjustment of displacement control of measuring beam flare spot for absolute laser ballistic gravimeters is described. This method is based on video registration of displacement trajectory of the measuring beam reflected from the corner reflector during the free fall of a body. The values and directions of the measuring beam angle relative to the vertical were determined

Abstract The paper describes a test workbench and its automation for studying a heat generator based on the Taylor–Couette flow between independently rotating multi-cylinder rotors. The technique of analyzing the spectra of pulsations of the drag force torque induced by the rotation of the heat generator rotors was used to study the flow structure. We present the techniques for recording the generated

Abstract A control algorithm based on the required differential equations of deviations is proposed to solve the problem of tracing the desired trajectory by target position. The flight path is planned on the basis of the author’s method of calculation of a flat trajectory consisting of oriented segments of straight lines connected by Euler spirals. The software and hardware complex of the automatic

Abstract Some results of the study of different circuits implementing the simultaneous mode locking and Q-switching of a resonator with the use of a spherical mirror and a travelling-wave acoustooptical modulator (SMAOM method) in a \(\textrm{Nd}:\textrm{YAG}\) laser are considered. The output time and energy characteristics are presented for a diode-pumped \(\textrm{Nd}:\textrm{YAG}\) laser with SMAOM

Abstract Delay in detecting the position and boundaries of the plasma confined by a tokamak increases plasma instability and decreases the accuracy of plasma control in tokamak. In this article, two techniques called ‘‘periodogram’’ and ‘‘cross-spectral analysis’’ are used to provide a quantitative approach for computing the time delay between data received by two diversity coils from one source (plasma

Abstract The possibility of forming a complex of spasers inside artificially created closed membranes (liposomes) is studied experimentally. The localization of the complexes inside liposomes is confirmed using a scanning confocal microscope. It is demonstrated that spasers retain their performance. The results show the liposome-encapsulated spasers can be effective theranostic agents.

Abstract One of the important problems of automatic threshold image segmentation by brightness are questions of the number of brightness classes and, as a consequence, the required number of thresholds. The solution to the problem of estimating the number of classes in an image is often based on representing its distribution as a mixture of distributions of brightness classes. It is known that this

Abstract Two algorithms for the determination of optical vortex coordinates are considered. In the first one, the vortex is found by branching of interference pattern fringes; in the second one, as a result of processing of the wavefront gradient distribution. It is shown that both algorithms allow one to record the coordinates with a high accuracy; in addition, it is possible to determine shifts of

Abstract The estimation of the scale parameter of the generalized Weibull probability density function by the criterion of the conditional risk minimum is considered and analyzed. Optimal estimates of the envelope intensity of the signals reflected from extended objects are obtained, provided that the intervals in the motion of these objects are independent random variables. These estimates are compared

Abstract The mathematical model for estimating a standard deviation of beat interference generated during photodetection of subcarrier signals with QPSK and M-QAM modulation formats is considered. The theory and the results of computer simulation are used to derive a formula for calculating the spectral distribution of beat interference depending on the number of signals and used modulation formats

Abstract The results of numerical studies of the effect of roundoff errors on the distribution of test statistics of statistical hypotheses are presented. The effect of the roundoff on the distribution of statistics of different goodness-of-fit and homogeneity tests is investigated. It is shown that, when the roundoff errors in the analyzed samples are comparable with the standard deviation of the

Abstract The article analyzes the method of pointing a high-spatial-resolution solar telescope with an angular field of view smaller than the angular size of the solar disk using an auxiliary guide telescope with the field of view covering the entire disk of the Sun and its surroundings. The requirements for the resolution of the telescope, pointing modes, and the structural diagram of the pointing

Abstract The paper develops a method for describing and estimating the state of a multidimensional dynamical object including the numerical-analytical representation of the general solution to the differential equation for the dynamical object and its measurable output, accounting for the domain of admissibility of time values and initial condition and of the uncertainty parameters in the right-hand

Abstract A brief review of works devoted to theoretical and experimental studies of structural and polarization transformations of laser beams in anisotropic crystals is presented. Generation of laser beams with a complex polarization-phase state is shown. It is demonstrated that adaptive tuning of structural and polarization-phase states can be carried out by relatively slow changes in the parameters

Abstract The possibility of using a digital micromirror device (DMD) for implementing the optical encryption with time integration in quasimonochromatic spatially incoherent light is considered. An experimental setup for optical registration of image to be encrypted on a digital camera is presented. Images containing text and graphic information are encrypted and successfully decrypted using inverse

Abstract Spectral diffraction lenses that have the same focusing distance for several specified wavelengths are proposed as a basis for a point light source with several specified wavelengths. A spectral diffraction lens designed to focus three wavelengths, 462, 608, and 952 nm (the wavelengths used to excite tubulin \(\beta\) fluorescence), is considered. For the production of spectral lenses, the

Abstract The results of the study of the influence that the object structure and its form of presentation have on the quality, resolution, and depth of field of images reconstructed using binary computer-generated hologram-projectors are presented. As a quality criterion for reconstructed image, the degree of correspondence of the reconstructed image to the object, estimated as the range of threshold

Abstract The current state of development and prospects of using metasurfaces in optics, in particular, in holography, is reviewed. Special attention is paid to the physics of the phase delay control of the meta-atom scattered radiation as well as to the transformation of the incident wavefront by the metasurface. A number of examples are presented to demonstrate the effectiveness of radiation focusing

Abstract Factors causing parasitic distortions of interferograms in control systems based on reference single-component high-aperture computer-generated holograms (CGHs), which are made on flat substrates and have a binary phase structure, are analyzed with respect to the problem of interferometric testing of spherical and aspherical surfaces with high angular apertures. The quality of such CGHs is

Abstract A method and an optical scheme for recording digital hyperspectral holograms in the light of an incoherent source are considered. The optical scheme includes an interferometer with a scanning mirror for generating reference waves. The set of complex amplitudes of the object field is calculated by Fourier transform of the interferograms in each pixel of the recording matrix. Experimental data

Abstract A multi-factor model of an optical encryption system with spatially incoherent illumination is proposed. This model takes into account the influence of the recording photosensor noise, changes in image resoltion during transmission through the optical system, spurious illumination, and noise from the synthesis of the encryption diffraction optical element on the quality of the decoded image

Abstract Binarization of digital holograms is used for storage and on-line transfer of registered information and for optical reconstruction of images using binary digital micromirror devices. The capabilities of binarization of optically registered holograms by iterative methods with application of the error diffusion method either at each step of varied binarization threshold or only at the final

Abstract A method and a device for measuring the main parameters of synthesized security holograms using the capabilities of micron resolution microscopy and diffractometry with a multi-angle illumination system are developed. The information surface map which contains data about the main parameters of holopixels, which make up the structure of a security hologram (diffraction grating period, their

Abstract Variants of implementing trackograms, one of the types of zero-order holograms, for the formation of protective features for non-expert verification of their authenticity are considered. The three-dimensional image in trackograms is formed by glares on the walls of toroidal surfaces-tracks that represent relief stripes with the recording material. Variations in the shape of tracks, their length

Abstract The application of two types of alternative action on gelatin in the layers of dichromated gelatin (DCG) was considered: structuring with the use of selective light tanning by the radiation of a He–Cd laser (\(\lambda=440\) nm) and destruction performed by exposure of layers to short-wave ultraviolet radiation (\(\lambda<270\) nm). The crucial role of UV exposure of samples in generating high-frequency

Abstract This paper presents the results of experimental studies and digital methods for recording of holograms using spatial light modulators. The use of holographic interference methods for measuring nanoscale irregularities is described for the case of a nanostep (70 nm in height and 30 \(\mu\)m in width). Examples are given of the method of increased sensitivity for nanostep measurements and the

The implementation of algorithms for comparative analysis of television image quality is considered. It is proposed to use the Xilinx Zynq-7000 platform, combining the advantages of FPGA and a general-purpose processor, to provide continuous on-line operation. An algorithm software architecture for comparing video signal quality by a full reference measurement method is proposed.

This paper first considers an approach based on the application of high-performance capacitive microstructures as anti-aliasing filters for low-frequency (sub-terahertz) measurements in terahertz time-domain spectroscopy. The approach was tested in measurements of the spectra of reference samples — bandpass filters with central frequencies of 156 and 376 GHz and a bandwidth of ∼12%. It is shown that

A swarm of moving objects coordinates the position of its individual objects in order to simultaneously solve a general problem set in a distributed manner. Planning the swarm operations comes across a problem of taking into account the possibility of operational regrouping of the swarm as the exact purpose of the swarm operation is not yet determined, or is a secret, or is set by a number of random

Specific features of spectral properties of volume reflection holograms are determined, namely, broadening of the spectral response (reflex) contour toward both the short-wave and long-wave spectral ranges in the case where the angle of incidence of the white-light probing beam differs from the direction of reference wave propagation in hologram recording. This effect is essentially different from

The possibility of the inference of neural networks on minifloats has been studied. Calculations using a float16 accumulator for intermediate computing were performed. Performance was tested on the GoogleNet, ResNet-50, and MobileNet-v2 convolutional neural network and the DeepSpeechv01 recurrent network. The experiments showed that the performance of these neural networks with 11-bit minifloats is

A new method is proposed for automatic classification of seismoacoustic emission sources in fiber optic monitoring systems based on the principles of optical reflectometry in a time domain using the time reconstruction of the interference signal phase. The novelty of this approach lies in the original principles of forming a space of classification features and the use of ensemble classifiers. This

An approach to filtration of hyperspectral images corrupted by the Gaussian additive noise is proposed. The approach is based on using the property of interchannel redundancy of such images. The developed algorithm of noise filtration allows maintaining the contour and brightness portraits of objects in individual components of the hyperspectral image, in contrast to algorithms of linear component-by-component

The principles of design of projectors of infrared (IR) scenes on the basis of micromirror technologies, which are the most promising devices for IR image generation, are analyzed. Several types of projectors based on these principles are considered from the viewpoint of functionality, noise minimization, and wavelength range in which these images are generated. Problems arising in design of IR scene

This paper presents a new integrated circuit designed for signal readout in a silicon microstrip detector in experimental observations of fast processes at a synchrotron radiation beam. The first variants of this circuit were used in a prototype detector based on a microstrip silicon sensor and were tested at an intense synchrotron radiation beam at the VEPP-4M storage ring in the Institute of Nuclear

Jet combustion of premixed propane-air mixtures is frequently encountered in various devices. In the present study, the flame is investigated by methods of the Hilbert optics. The diagnostic technique adapted to studying combustion products is based on visualization of phase perturbations induced in the probing light field by the examined medium with the use of polychromatic Hilbert and Foucault-Hilbert

Within the framework of geometric optics, this study analyzes the rotational tuning of the period of an interference pattern formed by converging light beams on a photodetector that is fixed relative to a mirrorless two-beam interferometer based on a beam-splitting cube. Equations are derived, whose solutions are the dependences of the tuning range on the base position of the initial light beam on

This paper deals with the fuzzy modeling of technological processes and objects for which it is impossible or difficult to develop adequate mathematical models using multidimensional interval-logic controllers. Proposed algorithms and the developed software are described. The results of calculations using fuzzy modeling methods showing high accuracy are presented.

The influence of a viewing device — a multifocal 3D display — on user’s visual perception and assessment of the depth and size of objects is analyzed. As an experiment model we used the Holway-Boring technique, which has proved that the constancy of size perception plays a decisive role in distance perception. A series of experiments has been performed showing that multifocal 3D displays provide fairly

A metal-dielectric narrow-band filter for a wavelength of 270 nm is designed within the framework of the conductive surface model to characterize the properties of thin metal films. It is demonstrated that inclusion of four thin molybdenum films into a multilayer dielectric structure ensures effective cut-off of the transmission at <1.5% in the visible range of the spectrum with the maximum transmittance

The existence of internal structural defects in gas insulated combinations (GIS) seriously affects the normal operation of equipment, and it needs an efficient and non-destructive detection method. This study is focused on the feasibility of X-ray digital imaging detection in GIS equipment monitoring. First, the digital imaging detection process is briefly introduced. Then, in order to obtain high-quality

In this paper, we consider two-signal and modified two-signal methods for measuring the S-parameters of passive two-ports and a method for adequately measuring the S-parameters of two-ports, such as transistors, developed on their basis. The methods are implemented using a coaxial simulator-analyzer of microwave amplifiers and oscillators in its measuring channels matched or mismatched with loads.

A control method and software structure for solving the problem of control of motion of a group of robots along a prescribed trajectory with preserving a chosen configuration under conditions of unsteady dynamic characteristics of individual robots is proposed.

Based on an analysis of differences between the experimentally measured temperature dependence of the current-voltage characteristic (I-V curve) of a laser diode bar (LDB) with AlGaAs/GaAs heterostructure and the dependence obtained in accordance with the well-known model of light-emitting diodes, assumptions were made about the sources of these differences. The agreement between the experimental and

In this paper, we propose a solution to the problem of designing a combined output control system for a nonlinear nonaffine plant with a delay in the control loop under a priori parametric uncertainty and external interference. Simulation results confirm the performance of the control system, and the resulting controller provides tracking of the plant to the reference signal.