Showing papers in "Optoelectronics, Instrumentation and Data Processing in 2018"
TL;DR: In this paper, the authors consider recent achievements and prospects for the main directions of research and improvement of architectures, technologies, and materials used in laboratories to develop solar cells with the best conversion efficiency.
Abstract: Multi-junction solar cells based on III–V compounds are the most efficient converters of solar energy to electricity and are widely used in space solar arrays and terrestrial photovoltaic modules with sunlight concentrators. All modern high-efficiency III–V solar cells are based on the long-developed triple-junction III–V GaInP/GaInAs/Ge heterostructure and have an almost limiting efficiency for a given architecture — 30 and 41.6% for space and terrestrial concentrated radiations, respectively. Currently, an increase in efficiency is achieved by converting from the 3-junction to the more efficient 4-, 5-, and even 6-junction III–V architectures: growth technologies and methods of post-growth treatment of structures have been developed, new materials with optimal bandgaps have been designed, and crystallographic parameters have been improved. In this review, we consider recent achievements and prospects for the main directions of research and improvement of architectures, technologies, and materials used in laboratories to develop solar cells with the best conversion efficiency: 35.8% for space, 38.8% for terrestrial, and 46.1% for concentrated sunlight. It is supposed that by 2020, the efficiency will approach 40% for direct space radiation and 50% for concentrated terrestrial solar radiation. This review considers the architecture and technologies of solar cells with record-breaking efficiency for terrestrial and space applications. It should be noted that in terrestrial power plants, the use of III–V SCs is economically advantageous in systems with sunlight concentrators.
28 citations
TL;DR: Functional possibilities, architectural features, and user interface of the distributed web geographic information system of ecological monitoring of the city of Krasnoyarsk, which is being developed in service-oriented architecture, are discussed.
Abstract: This paper touches upon the experience of research and development of hardware and software for air pollution monitoring of industrial cities, carried out at the Institute of Computational Modeling of the Siberian Branch of the Russian Academy of Sciences. Functional possibilities, architectural features, and user interface of the distributed web geographic information system of ecological monitoring of the city of Krasnoyarsk, which is being developed in service-oriented architecture, are discussed. Data are collected from automated posts for observing the state of atmospheric air and services of aggregation and representation of information in the form of interactive graphs and thematic maps in the web interface. An original device is developed for measuring the pollution level of the atmosphere with fine dust (PM2.5), the data from which is fed in real time to the system via a cellular network. A system is formed for integral assessment of the pollution level of the atmosphere based on Air Quality Index (AQI) calculations.
22 citations
TL;DR: In this paper, a review of recent work in the field of formation of a 3D profile of optical elements with the use of direct laser writing at various wavelengths and photolithographic technologies on the basis of photomasks fabricated by means of laser writing is reviewed.
Abstract: Recent research in the field of formation of a 3D profile of optical elements with the use of direct laser writing at various wavelengths and photolithographic technologies on the basis of photomasks fabricated by means of laser writing is reviewed. Typical characteristics of the relief, as well as advantages and drawbacks of the above-mentioned methods are considered.
17 citations
TL;DR: The best results are obtained by using preprocessing of “raw” data before the procedures of pixel-wise spectral classification in spectral-spatial classification of hyperspectral data.
Abstract: Various methods of spectral-spatial classification of hyperspectral data are reviewed. Papers devoted to the most popular ways of using spatial information for increasing the accuracy of classification maps are considered. It is shown that the best results are obtained by using preprocessing of “raw” data before the procedures of pixel-wise spectral classification. Disadvantages, limits, and possible directions for developing existing methods are investigated and analyzed.
16 citations
TL;DR: It is shown that the accuracy of regime classification reaches 98% on the flame images of a gas burner and the results of the operation of the convolutional neural network and classification using different linear models are compared.
Abstract: A method for automatic determination of combustion regimes using flame images on the basis of a convolutional neural network on labeled data is under consideration. It is shown that the accuracy of regime classification reaches 98% on the flame images of a gas burner. The results of the operation of the convolutional neural network and classification using different linear models are compared.
13 citations
TL;DR: In this paper, the possibility of using computer-generated Fresnel holograms to determine phase aberrations of a wavefront is studied, and the results of computer simulation of the propagation of an elementary signal based on the Fresnel integral transform are presented.
Abstract: The possibility of using computer-generated Fresnel holograms to determine phase aberrations of a wavefront is studied. The results of computer simulation of the propagation of an elementary signal based on the Fresnel integral transform are presented. The principle of operation of a hologram for a wavefront sensor is discussed.
12 citations
TL;DR: In this paper, a nonparametric pattern recognition algorithm corresponding to the maximum likelihood criterion with additional decision functions is considered and the synthesis of the proposed algorithms is based on the analysis of the ratios of the estimates of the probability density distributions of random variables in classes and their functionals with input thresholds.
Abstract: Modifications of a nonparametric pattern recognition algorithm corresponding to the maximum likelihood criterion with additional decision functions are considered. The synthesis of the proposed algorithms is based on the analysis of the ratios of the estimates of the probability density distributions of random variables in classes and their functionals with input thresholds. The choice of the thresholds is determined by specific features of the classification problem. The results obtained are applied for assessing the states of forest tracts on the basis of remote sensing data.
12 citations
TL;DR: Test calculations based on model and real data are used to show the effectiveness of the proposed approach to recognizing objects from hyperspectral images.
Abstract: This paper describes a problem of thematic processing of hyperspectral aerospace images. A recommended technique is based on a decoding algorithm and makes it possible to construct an effective algorithm of multiclass classification based on combining standard algorithms of binary classification of various complexity. The reason for choosing the configuration of the classification algorithm is given. Test calculations based on model and real data are used to show the effectiveness of the proposed approach to recognizing objects from hyperspectral images.
11 citations
TL;DR: In this article, a deformable mirror control method for high and low spatial frequencies is described, and results of preliminary experiments aimed at developing algorithms for deformable mirrors control are reported.
Abstract: Control methods with the use of two deformable mirrors (correcting aberrations of high and low spatial frequencies, respectively) are briefly described. Results of preliminary experiments aimed at developing algorithms for deformable mirror control are reported.
9 citations
TL;DR: In this paper, a prototype of a key element of adaptive-optics systems is designed, a controlled flat mirror used to correct light beam tilts, and an algorithm for correcting atmospheric distortions of low-intensity light waves and real-time software are developed.
Abstract: A prototype of a key element of adaptive-optics systems — a controlled flat mirror used to correct light beam tilts — was designed. An algorithm for correcting atmospheric distortions of low-intensity light waves and real-time software were developed. In laboratory experiments, a value of 100 Hz was achieved for the bandwidth of a closed-loop system. The efficiency of the developed software was confirmed by daytime observations of stars.
8 citations
TL;DR: A method of lossless compression of geometric data based on perturbation functions is proposed and advantages of this approach over the known algorithms of transformation of three-dimensional models for fast transmission of information and its compact storage are demonstrated.
Abstract: This paper touches upon the problem of a compact polygonal description of objects. A method of lossless compression of geometric data based on perturbation functions is proposed. Advantages of this approach over the known algorithms of transformation of three-dimensional models for fast transmission of information and its compact storage are demonstrated.
TL;DR: It is shown that, by specifying the type of action and the transfer function of a smoothing chain, it is possible to determine the steady-state dynamic and fluctuation errors in a closed servo-system.
Abstract: This paper describes the synthesis of algorithms for estimating signal information parameters with noninertial nonlinear transformation of the input mixture of the signal and broadband non-Gaussian noise. There is also the analysis of algorithms optimal in the domain of small mismatch and quasioptimal algorithms, which are capable of operating in arbitrary mismatches between measured parameters and their estimates in the case of random signal/noise ratio at the gauge input. This work also presents the obtained basic estimated relations that help one determine the form of optimal amplitude characteristics of the nonlinear transformation unit, the quality of suppression of additive noise in a given unit with optimal and arbitrary amplitude characteristic, the steepness of the discrimination characteristic, and the value of the phase characteristic in the domain of small mismatches. It is shown that, by specifying the type of action and the transfer function of a smoothing chain, it is possible to determine the steady-state dynamic and fluctuation errors in a closed servo-system.
TL;DR: In this article, a new method of increasing the spatial resolution in digital holographic microscopy is considered, based on supplementing the initial hologram with results measured in the case of photodetector shifting in space by a value smaller than the resolution used.
Abstract: A new method of increasing the spatial resolution in digital holographic microscopy is considered The method is based on supplementing the initial hologram with results measured in the case of photodetector shifting in space by a value smaller than the resolution used In contrast to other known approaches, this method does not require a system of equations to be solved
TL;DR: In this article, the authors describe the development and investigation of compact waveguide electrooptic modulators using original synthesized chromophore-containing polyimides with covalently attached commercial DR-13 dye.
Abstract: This paper describes the development and investigation of compact waveguide electrooptic modulators using original synthesized chromophore-containing polyimides with covalently attached commercial DR-13 dye. Fully polymer planar electro-optic structures with phase-polarization and amplitude modulators in the form of a Mach–Zehnder interferometer were developed and implemented. The characteristics of the developed modulators at a wavelength of 1.3 μm were investigated, and a half-wave voltage of 24 V was achieved with a 1.3 cm length of the active part of the modulator.
TL;DR: In this article, a method of fabrication of thick resistive masks is described, which can be used for solving various engineering problems, e.g., for fabricating x-ray-absorbing topological patterns for LIGA masks, stamp microrelief, cast moulds, etc.
Abstract: A method of fabrication of thick (~100 μm and more) resistive masks is described. These masks can be used for solving various engineering problems, e.g., for fabricating x-ray-absorbing topological patterns for LIGA masks, stamp microrelief, cast moulds, etc. Specific features of the contact photolithography method, which is used to design and fabricate the research device, are described. A source of exposure radiation in this device is a light-emitting diode. A possibility of obtaining individual elements of the resistive mask (in particular, with the lateral size ~5 μm, height of ~70 μm, and aspect ratio of ~14) and also the titanium stamp microrelief (with the height up to ~40 μm) generated by means of reactive ion-beam etching through the resistive mask, is experimentally demonstrated.
TL;DR: In this article, the intensity of the line of antisymmetric vibrations of CH2 in the Raman spectrum of molecular layers of fatty acids and phospholipids is determined to a large extent by their interaction with electron excitation of the hydrocarbon chain.
Abstract: The intensity of the line of antisymmetric vibrations of CH2 in the Raman spectrum of molecular layers of fatty acids and phospholipids is sensitive both to the molecular order in the layer (lateral order) and to the conformational order of the hydrocarbon chain of the molecule. Though the intensity of this line is widely used as an indicator of order in molecular layers containing hydrocarbon tails, the nature of sensitivity of the line of antisymmetric vibrations to the order is still disputable. This issue has been experimentally studied, and it has been demonstrated that disordering leads to redistribution of vibrational modes and to changes in polarizability of antisymmetric vibrations. A hypothesis is proposed that the intensity of the line of the Raman scattering of antisymmetric vibrations of CH2 is determined to a large extent by their interaction with electron excitation of the hydrocarbon chain.
TL;DR: It is shown that simultaneous allowance for spatial and spectral features ensures highquality classification of similarly looking types of vegetation by merely using training sets with the maximum degree of the pixel distribution over the image.
Abstract: The efficiency of the methods of controlled spectral and spectral-spatial classification of vegetation types on the basis of hyperspectral pictures with different methods of training set formation is evaluated. The dependence of the classification accuracy on the number of spectral features is considered. It is shown that simultaneous allowance for spatial and spectral features ensures highquality classification of similarly looking types of vegetation by merely using training sets with the maximum degree of the pixel distribution over the image.
TL;DR: In this paper, a two-dimensional PC Y-junction power splitter based on the resonance effect with circular air holes etched on a hexagonal lattice with a period a is proposed.
Abstract: Nano-photonics is an emerging area of optical materials, which would take the optointegrated circuits towards progress. Photonic crystal (PC) based power splitters are useful constituents for the design of photonic integrated circuits (PICs). They are very important devices for connecting different building blocks on an integrated optical chip. In this paper, a two-dimensional PC Y-junction power splitter (21×15 μm) based on the resonance effect with circular air holes etched on a hexagonal lattice with a period a is proposed. The plane wave expansion (PWE) and finite difference time domain (FDTD) techniques are used for analyzing the structure. The simulation results show that the optimum resonance occurs when the radius of the defect hole is 0.3a, leading to the maximum and equal power distribution.
TL;DR: There is an approach proposed for the development of the Gradient scalable application for solving the problem of global optimization of multiextremal functions with account for a multistart method in the Orlando framework.
Abstract: This paper describes the urgent issue of providing scalability of computations in the solution of multiextremal problems arising in different fields of scientific studies, including image processing. There is an approach proposed for the development of the Gradient scalable application for solving the problem of global optimization of multiextremal functions with account for a multistart method in the Orlando framework. An additional step of computations is implemented in the problem solving scheme, which makes it possible to decompose the problem with account for the performance of computational resources and thereby minimize the time it takes to solve it as opposed to a classical multistart method. Special agents of the metamonitoring system for measuring the performance of resource with regard to the problem solved are developed.
TL;DR: In this article, the effect of polarity of the medium and micro-emulsion on nonlinear optical properties of saffron was studied by the Z-scan technique with a CW laser at the 532 nm wavelength.
Abstract: Molecules with strong two-photon absorption have applications in photodynamic therapy and photonic devices. The effect of polarity of the medium and microemulsion on nonlinear optical properties of saffron is studied by the Z-scan technique with a CW laser at the 532 nm wavelength. The values of the nonlinear refractive index and two-photon absorption of saffron are found to increase with a decrease in the medium polarity and with an increase in the droplet size in the microemulsion.
TL;DR: In this paper, the diffraction pattern of radiation reflected from the surface microrelief of the considered element or transmitted through it in the angular range of diffraction of the order of ±90° and 360° in terms of the azimuthal angle.
Abstract: Results of the development and testing of a device for detecting and analyzing the diffraction pattern of computer-generated holograms are reported. It is demonstrated that this device allows characterization of the diffraction pattern of radiation reflected from the surface microrelief of the considered element or transmitted through it in the angular range of diffraction of the order of ±90° and 360° in terms of the azimuthal angle. A possibility of determining the periods, duty cycle, and angular orientation of diffraction structures and also the diffraction efficiency of all diffraction orders of the examined element is described. The device is designed for real-time monitoring of the microrelief depth and shape of computer-generated holograms in the course of their fabrication.
TL;DR: In this paper, a non-contact sensor for measuring distance to liquid surfaces which provides signaling upon reaching a prescribed value is designed, and an overview of triangulation measurement systems is given.
Abstract: Metrological analysis of triangulation laser sensors for measuring distance to mirror surfaces was performed. Theoretical and experimental studies have established that the measurement range of distance depends on the angle of incidence of the laser beam, and the main factor that affects the measurement accuracy is the rotation of the sensor in the plane of incidence. A non-contact sensor for measuring distance to liquid surfaces which provides signaling upon reaching a prescribed value is designed. An overview of triangulation measurement systems is given.
TL;DR: In this article, the influence of dislocation filters based on low-temperature layers of GaAs and postgrowth annealing on the perfect GaAs/Si heterostructures is discussed.
Abstract: The influence of dislocation filters based on low-temperature layers (LT) of GaAs and postgrowth annealing on the perfection of GaAs/Si heterostructures is discussed. It is shown that LT-GaAs layers reduce the density of threading dislocations and surface roughness. Post-growth annealing at a temperature of 650 °C reduces the concentration of nonradiative recombination centers in GaAs/Si layers to a level close to the level in GaAs layers grown on a matched substrate.
TL;DR: In this paper, the spatial distribution of the local quantum efficiency over the area of photodiode-based IR focal plane arrays (IR FPA) was calculated by Monte-Carlo simulation.
Abstract: The results of calculation of the spatial distribution of the local quantum efficiency over the area of photodiode-based IR focal plane arrays (IR FPA) are presented. The diffusion of photogenerated charge carriers in the absorber layer of the array was calculated by Monte-Carlo simulation. Methods of reducing the amount of necessary calculations based on using the symmetry properties of the array are discussed. Requirements for the photoelectric and design parameters (absorber-layer thickness, chargecarrier diffusion length and optical absorption length in this layer, the ratio of the size of n–p junctions to the geometrical dimensions of the detector pixels) are formulated that ensure the threshold sensitivity and spatial resolution of IR FPAs.
TL;DR: In this article, the concept and methods of space-time processing of radio images of small objects in a multiposition radiometer system are described, which make it possible to increase the performance of this system.
Abstract: This paper describes the concept and methods of space-time processing of radio images of small objects in a multiposition radiometer system, which make it possible to increase the performance of this system. The spatial processing is carried out in each overlook cycle of scanning radiometers in order to determine the spatial coordinates of objects and mutual orientation of coordinate systems. The time processing is carried out in a sequence of overlook cycles of radiometers for determining the trajectory of the objects that change mutual positions.
TL;DR: In this article, a point-to-point 3D laser heterodyne microprobing is proposed to study internal phase inhomogeneities in transparent optical materials by point to point three-dimensional laser HetNets.
Abstract: A method for studying internal phase inhomogeneities in transparent optical materials by point-to-point three-dimensional laser heterodyne microprobing is proposed. The light microprobe in this case is a traveling micrograting formed in the zone of overlapping of two focused coherent light beams: reference and signal. The size of the microprobe in the x, y, z directions and the degree of influence of spherical aberration with a change in the microprobing depth are estimated. The capabilities of the method are illustrated by examples of detection and subsequent imaging of phase inhomogeneities in the volume of laser ceramics and its random layers.
TL;DR: Thematic processing of multispectral satellite images by software for object recognition, detection and mapping of lineaments and circular structures, as well as determination of spatial displacements of natural objects over time-different satellite images is described.
Abstract: This paper describes a PlanetaMonitoring software complex, developed jointly by the Scientific Research Center “Planeta” and the Institute of Computational Mathematics and Mathematical Geophysics of the Siberian Branch of the Russian Academy of Sciences, which implements the software for pre-processing and thematic processing of multispectral satellite images of optical, infrared, and microwave ranges. This work also touches upon the pre-processing of satellite data, particularly brightness and geometric transformations, geocoding, and compilation of survey installation. Thematic processing of multispectral satellite images by software for object recognition (without and with training), detection and mapping of lineaments and circular structures, as well as determination of spatial displacements of natural objects (ice fields, water masses, and cloud formations in the atmosphere) over time-different satellite images is described. This software is used to solve a number of applied problems of Earth remote sensing.
TL;DR: In this article, a mathematical model is developed for calculating the beating noise that occurs during photodetection of a single-band optical OFDM signal, which allows one to estimate the spectral distribution of the beating noises and the distortion of the OFDM subcarrier levels due to fiber dispersion.
Abstract: A mathematical model is developed for calculating the beating noise that occurs during photodetection of a single-band optical OFDM signal The model allows one to estimate the spectral distribution of the beating noise and the distortion of the OFDM signal subcarrier levels due to fiber dispersion The influence of the beating noise on orthogonal subcarrier channels, possible ways of increasing the system transmission capacity, and the method of noise compensation on the receiving side are investigated
TL;DR: In this article, an analytical expression for the pulse response is derived for the first time, and the response behavior is studied for various relationships of the objective and filter apertures.
Abstract: Characteristics of spatially non-invariant telecentric projection systems, which are widely used in practice, are considered within the framework of wave optics. In the class of the Fresnel functions, the pulse response of the system is precisely calculated for various values of the projection objective and filter apertures. It is found that the response consists of two components, which determine the invariant and non-invariant properties of the system, respectively. Based on the approximation of the Fresnel function by elementary functions proposed previously by the author, an analytical expression for the pulse response is derived for the first time, and the response behavior is studied for various relationships of the objective and filter apertures. The correctness of choosing the parameters of the known quasi-invariant optical systems is analyzed. Recommendations on choosing the filter aperture are given to improve their spatially invariant characteristics. In contrast to available optical and geometrical methods, the proposed approach allows one to obtain reliable information about the character of wave field transformations in the considered systems.
TL;DR: In this article, the authors studied the spectrum distortion of the D1-line of 85Rb in optical cells with an antirelaxation coating on the inner walls of the cell.
Abstract: Distortion of the spectrum of the D1-line of 85Rb in optical cells with an antirelaxation coating on the inner walls of the cell is studied. The spectrum shape is found to be significantly dependent on the velocity and direction of changes in the laser frequency. A physical explanation is provided for these features, which are confirmed by numerical simulations. The effect of the magnetic field on the spectrum shape is discussed.