+
VORTEX BEAMS IN TURBULENT MEDIA: REVIEW
стр.605-624
Soifer V.A., Korotkova O., Khonina S.N., Shchepakina E.A.
The review covers publications concerned with propagation of laser beams through turbulent media described by the Kolmogorov theory and generalizations thereof to describe signal transmission in optical communications and detection systems. In this case, the turbulent medium is interpreted as an optical channel with random parameters. Various optical signals considered include partially coherent beams, non-uniformly polarized vector beams, as well as specifically configured spatial laser beams. Special attention is given to vortex laser beams. The latter are shown to have a number of remarkable properties that give them an advantage over conventional Gaussian beams.
Загружаем данные из библиотечной системы...
Ключевые слова
+
INTERFEROMETRIC TESTING OF STEEP CYLINDRICAL SURFACES WITH ON-AXIS CGHS
стр.625-628
Poleshchuk A.G., Nasyrov R.K., Asfour J.M.
We present a new approach for testing cylindrical optical surfaces using a -test. We suggest using a Computer Generated Hologram (CGH) in combination with a Transmission Sphere. It is shown that in such an optical layout the period of the diffractive structure is larger than in the case of a conventional scheme using a collimated beam. Therefore, this kind of hologram enables the test of cylinder surfaces with higher numerical apertures.
Загружаем данные из библиотечной системы...
Ключевые слова
+
TIGHT FOCUSING OF LASER LIGHT USING A SURFACE PLASMON POLARITON IN A SILVER NANO-STRIP AND NANO-RING ON SILICA GLASS
стр.629-634
Kozlova E.S., Kotlyar V.V.
In this work a solitary surface plasmon-polariton was obtained by using a frequency-dependent finite difference time-domain method for the TM- and radially polarized light at 532 nm, which was propagated through silver nano-elements (a nano-strip and a nano-ring), placed in an aqueous medium. The device's height and width were equal to 20 nm and 215 nm respectively. The intensity of surface plasmon-polariton was four times higher than that of the incident radiation. The full width at half maximum of the nanojet was 138 nm and 158 nm for the case of using a nano-strip and a nano-ring respectively. The results can be used to design devices that allow capturing and moving particles in water or other biofluids.
Загружаем данные из библиотечной системы...
Ключевые слова
+
SCATTERING OF LIGHT FROM HOLLOW AND SEMI-HOLLOW 3D SCATTERERS WITH ELLIPSOIDAL, CYLINDRICAL AND CARTESIAN SYMMETRIES
стр.635-641
Scattering potentials of hollow particles with ellipsoid-, cylinder- and parallelepiped-like shapes and adjustable edge sharpness are introduced as a difference of two 3D multi-Gaussian functions with suitable parameters. The far-zone intensity distributions generated on weak scattering from such potentials are shown to depend on the scatterer’s boundary thickness, edge softness as well as on its size relative to the wavelength. Possible extension to potentials formed by nested shells of the same or different types and potentials with semi-hollow center is outlined.
Загружаем данные из библиотечной системы...
Ключевые слова
+
TIGHTLY FOCUSED LASER LIGHT WITH AZIMUTHAL POLARIZATION AND SINGULAR PHASE
стр.642-648
Kotlyar V.V., Nalimov A.G.
Using simplified Richards-Wolf formulas we show that laser light with azimuthal polarization and singular phase can produce a smaller focal spot than that from a laser beam with radial polarization, other conditions remaining the same. It is numerically shown that when focusing an azimuthally polarized laser beam with phase singularity using a zone plate a 1.3 times smaller focal spot can be attained than when an aplanatic lens is used. A spiral phase plate can be replaced with a phase step with a π-phase shift. In this case the subwavelength focal spot from a laser beam with azimuthal polarization, which is formed near the zone plate surface, loses circular symmetry, while becoming smaller and acquiring an elliptical form with radiuses of 0.273λ and 0.314λ (NA = 1).
Загружаем данные из библиотечной системы...
Ключевые слова
+
MASTER EQUATION AVERAGED OVER STOCHASTIC PROCESS REALIZATIONS FOR THE DESCRIPTION OF A THREE-LEVEL ATOM RELAXATION
стр.649-653
Mikhailov V.A., Troshkin N.V.
The relaxation of a three-level atom interacting with a photon heat bath and an external stochastic field is investigated. For the reduced density matrix, a master equation averaged over stochastic process realizations is derived. An exact solution is obtained and the radiation line shapes are calculated.
Загружаем данные из библиотечной системы...
Ключевые слова
+
HIGH PERFORMANCE 2D SIMULATIONS FOR THE PROBLEM OF OPTICAL BREAKDOWN
стр.654-658
Methods of numerical simulation of two-dimensional short laser pulse nonlinear dynamics are discussed. In this work parallel processing methods for modern CPU (central processing units) architectures supporting non-uniform memory access are considered. The method of adaptive mesh subdivision is proposed to reduce non-uniform load of each CPU during processing of nonlinearity. The results of the tests performed on the Intel Nehalem based a workstation with eight cores are presented.
Загружаем данные из библиотечной системы...
Ключевые слова
+
SIMULATION OF FORMING PROCESSES WITH LOCAL HEATING OF DUAL PHASE STEELS WITH USE OF LASER BEAM SHAPING SYSTEMS
стр.659-667
Bielak R., Bammer F., Otto A., Stiglbrunner Ch.F., Colasse C., Murzin S.P.
Features of laser-assisted warm forming of dual phase steel DP1000 are determined. Simulation of forming processes with local heating is performed. In the simulation procedure, the forming parameters of three dimensional forming were adapted to keep them within tolerable limits even in critical areas as well as identifying the localization and type of critical stresses. The capabilities of Abaqus were extended by use of the Python language to independently evaluate selected element strains, the position of deformed elements within the forming limit diagram and user-defined failure criteria. The simulation led to an adapted forming process permitting a significantly increased bulge forming depth by local laser heating of the forming zones. The developed simulation model shows a satisfactory conformity with experiments, performed using a fibre-coupled laser with a wavelength of 1070 nm and a maximum output power of 1500 W, and a servo bending press TRUMPF TruBend 7018. The required distribution of the laser beam energy can be obtained by using diffractive optical elements. The use of the model for technological operations opens up possibilities not only for the solution of the presented specific objective of laser assisted warm forming, but also for others applications.
Загружаем данные из библиотечной системы...
Ключевые слова
+
DESIGN, SIMULATION, AND FABRICATION OF SILICON-ON-INSULATOR MEMS VIBRATORY DECOUPLED GYROSCOPE
стр.668-673
Verma P., Pavelyev V.S., Volodkin B.O., Tukmakov K.N., Reshetnikov A.S., Andreeva T.V., Fomchenkov S.A., Khonina S.N.
This paper reports the design and fabrication of a 2-degree-of-freedom (DOF) decoupled vibratory gyroscope based on a silicon-on-insulator (SOI) MEMS process. The 2-DOF capacitive comb structure is deliberately designed to have a decoupled drive and sense mode oscillation to prevent the unstable operation due to mechanical coupling, resulting in a low zero rate out-put drift. It is well known that the closer are the drive and sense resonances, the higher is the angular rate resolution of the gyroscope. Generally, this is achieved by using symmetric suspensions, but it results in a reduced bandwidth. The proposed design has been configured to achieve a bandwidth of about 150 Hz, while ensuring the decoupled operation of the drive and sense modes. An analytical method has been employed to study the steady state response of the 2-DOF structure. FEM analysis has been carried out in CoventorWare® MEMS Design software and the simulation results show that the drive resonance occurs at 21.48 kHz and sense resonance at 21.63 kHz, which are in close agreement with the theoretical results. The structure is designed with a 15 µm thick device layer. Fabrication of the design is proposed using a two mask process based on Deep reactive-ion etching (DRIE) and sacrificial wet release etching on a SOI wafer. DRIE etching with an aspect ratio of 1:5 has been successfully carried out as desired and the results have been presented.
Загружаем данные из библиотечной системы...
Ключевые слова
+
MODELLING OF MULTILAYER DIELECTRIC FILTERS BASED ON TIO2 / SIO2 AND TIO2 / MGF2 FOR FLUORESCENCE MICROSCOPY IMAGING
стр.674-678
Butt M.A., Fomchenkov S.A., Ullah A., Habib M., Ali R.Z.
We report a design for creating multilayer dielectric optical filters based on TiO2 and SiO2/MgF2 alternating layers. We have selected Titanium dioxide (TiO2) for high refractive index (2.5), Silicon dioxide (SiO2) and Magnesium fluoride (MgF2) as a low refractive index layer (1.45 and 1.37) respectively. Miniaturized visible spectrometers are useful for quick and mobile characterization of biological samples. Such devices can be fabricated by using Fabry-Perot (FP) filters consisting of two highly reflecting mirrors with a central cavity in between. Distributed Bragg Re-flectors (DBRs) consisting of alternating high and low refractive index material pairs are the most commonly used mirrors in FP filters, due to their high reflectivity. However, DBRs have high re-flectivity for a selected range of wavelengths known as the stopband of the DBR. This range is usually much smaller than the sensitivity range of the spectrometer. Therefore, bandpass filters are required to restrict the wavelength outside the stopband of the FP DBRs. The proposed filter shows high quality with an average transmission of 97 % within the passbands and the transmission outside the passband is around 3 %. Special attention has been given to keep the thickness of the filters within the economic limits. It can be suggested that these filters are exceptionally promising for florescence imaging and narrow-band imaging endoscopy.
Загружаем данные из библиотечной системы...
Ключевые слова
+
ALGORITHM FOR CALCULATION OF THE POWER DENSITY DISTRIBUTION OF THE LASER BEAM TO CREATE A DESIRED THERMAL EFFECT ON TECHNOLOGICAL OBJECTS
стр.679-684
Murzin S.P., Bielak R., Liedl G.
Based on the use of methods for solving the inverse problem of heat conduction, we developed an algorithm for calculating the power density distribution of the laser beam to create a desired thermal effect on technological objects. It was shown that the redistribution of power density of moving distributed surface heat sources can adjust the temperature distribution in the treated zone. The results of thermal processes calculation show the ability of the developed algorithm to create a more uniform temperature field across the width of the heat affected zone. Equalization of maximum temperature values is achieved in the center and on the periphery of the heat affected zone with an increase in the width of the regions, where required temperature is reached. The application of diffractive optical elements gives an opportunity to obtain the required properties of treated materials in the heat affected zone. The research performed has enabled parameters of the temperature field in chrome-nickel-molybdenum steel to be adjusted for laser heat treatment. In addition to achieving uniform temperature conditions across the width of the heat affected zone, the proposed approach allows the increase of the width of the isotherms of the temperature fields; this provides an opportunity to process a larger area per unit time at the same laser beam power.
Загружаем данные из библиотечной системы...
Ключевые слова
+
TUNABLE DIFFRACTION GRATING WITH TRANSPARENT INDIUM-TIN OXIDE ELECTRODES ON A LITHIUM NIOBATE X-CUT CRYSTAL
стр.685-688
Paranin V.D., Karpeev S.V., Tukmakov K.N., Volodkin B.O.
A tunable diffraction grating based on an electrooptic X-cut lithium niobate crystal has been manufactured and experimentally analyzed. The period of electrodes is 290 μm, the electrode width is 117.5 μm, and the thickness of an electrode is 150 - 160 nm. The electrodes are made of a transparent conducting indium-tin oxide that serves as an antireflection coating with the aim of increasing the optical transmission. In order to prevent crystal polarization switching and electrical breakdown an optimized electrode topology with end ellipticity 1:1 and increased interelectrode gap is used. The optical diagram of the tunable grating with alternating electrode potentials for various gap voltages is analyzed. The intensity of the zero order of diffraction is shown to decrease by 40 % at a voltage of 800 V. At the same time, the origination of new diffraction orders at angles ± λ / (2 d ) is noted. The measurement of the forward-bias and reverse-bias regions of the modulation characteristic reveals the absence of hysteresis, which confirms the correctness of the electrode topology design.
Загружаем данные из библиотечной системы...
Ключевые слова
+
HYPERSPECTRAL REMOTE SENSING DATA COMPRESSION AND PROTECTION
стр.689-712
Gashnikov M.V., Glumov N.I., Kuznetsov A.V., Mitekin V.A., Myasnikov V.V., Sergeyev V.V.
In this paper, we consider methods for hyperspectral image processing, required in systems of image formation, storage, and transmission and aimed at solving problems of data compression and protection. A modification of the digital image compression method based on a hierarchical grid interpolation is proposed. Methods of active (on the basis of digital watermarking) and passive (on the basis of artificial image distortion detection) data protection against unauthorized dissemination are developed and investigated.
Загружаем данные из библиотечной системы...
Ключевые слова
+
DEVELOPMENT OF AN ALGORITHM FOR AUTOMATIC CONSTRUCTION OF A COMPUTATIONAL PROCEDURE OF LOCAL IMAGE PROCESSING, BASED ON THE HIERARCHICAL REGRESSION
стр.713-720
Kopenkov V.N., Myasnikov V.V.
In this paper, we propose an algorithm for the automatic construction (design) of a computational procedure for non-linear local processing of digital signals/images. The aim of this research is to work out an image processing algorithm with a predetermined computational complexity and achieve the best quality of processing on the existing data set, while avoiding a problem of retraining or doing with less training. To achieve this aim we use a local discrete wavelet transform for a preliminary image analysis and the hierarchical regression to construct a local image processing procedure on the basis of a training dataset. Moreover, we work out a method to decide whether the training process should be completed or continued. This method is based on the functional of full cross-validation control, which allows us to construct the processing procedure with a predetermined computational complexity and veracity, and with the best quality.
Загружаем данные из библиотечной системы...
Ключевые слова
+
THE HYBRID CPU/GPU IMPLEMENTATION OF THE COMPUTATIONAL PROCEDURE FOR DIGITAL TERRAIN MODELS GENERATION FROM SATELLITE IMAGES
стр.721-728
Fursov V.A., Goshin Ye.V., Kotov A.P.
In this paper a procedure of building a digital terrain model (DTM) from the satellite images is researched. The procedure is based on the authors' previously developed algorithms of fast image matching for building disparity maps implemented on GPUs (Graphics Processing Units). In this paper we propose a computational procedure for constructing a DTM from the satellite stereo images. Experimental studies have shown that while this procedure constructs a DTM that may be less accurate than the one achieved with the use of the ENVI software, it offers a significantly shorter time of processing.
Загружаем данные из библиотечной системы...
Ключевые слова
+
FACE PHOTO RETRIEVAL BASED ON SKETCHES
стр.729-739
Kukharev G.A., Shchegoleva N.L.
The paper deals with the problem of the automatic retrieval of face photos using sketch drawings based on the witness description. We propose new methods for the generation of a sketch population from the initial one to improve the performance of sketch-based photo image retrieval systems. The method based on the computation of an average sketch from the generated population has been applied to increase the index of similarity in sketch-photo pairs. It is shown that such sketches are more similar to the original photographic images and their use leads to good results. Results of the experiments on CUHK Face Sketch and CUHK Face Sketch FERET databases and open access databases of photo-sketches pairs are discussed.
Загружаем данные из библиотечной системы...
Ключевые слова
+
FACE RECOGNITION BASED ON THE PROXIMITY MEASURE CLUSTERING
стр.740-745
Nemirovskiy V.B., Stoyanov A.K., Goremykina D.S.
In this paper problems of featureless face recognition are considered. The recognition is based on clustering the proximity measures between the distributions of brightness clusters cardinality for segmented images. As a proximity measure three types of distances are used in this work: the Euclidean, cosine and Kullback-Leibler distances. Image segmentation and proximity measure clustering are carried out by means of a software model of the recurrent neural network. Results of the experimental studies of the proposed approach are presented.
Загружаем данные из библиотечной системы...
Ключевые слова
+
AUTOMATIC TARGET RECOGNITION ALGORITHM FOR LOW-COUNT TERAHERTZ IMAGES
стр.746-751
The paper presents the results of developing an algorithm for automatic target recognition in broadband (0.1-10) terahertz images. Due to the physical properties of terahertz radiation and associated hardware, such images have low contrast, low signal-to-noise ratio and low resolution - i.e. all the characteristics of a low-count images. Therefore, standard recognition algorithms designed for conventional images work poorly or are not suitable at all for the problem considered. We have developed a fundamentally different approach based on clustering 2D point clouds in accordance with a set of predefined patterns. As a result, we reduce the problem of target recognition to the problem of maximizing the image data likelihood with respect to the classes of model objects up to the size and position. The resulting recognition algorithm has a structure close to that of the well-known EM algorithm; its formal scheme is at the end of the paper.
Загружаем данные из библиотечной системы...
Ключевые слова
+
VULNERABILITY ANALYSIS ON HYDERABAD CITY, INDIA
стр.752-758
Boori M.S., Choudhary K., Kupriyanov A.V.
City vulnerability is an assessment of priorities for implementation in a city. Thus, it is imperative to determine vulnerable regions in the city to identify priority areas that may require immediate intervention. Several methods used for national, international and local level vulnerability assessment are based on remote sensing and GIS technology. This paper aims to determine the vulnerability of Hyderabad city using a geospatial based vulnerability index for sustainable development of the city. We use an urbanization and vulnerability concept for the development of city policy measures. We assessed the city vulnerability using a conceptual diagram composed of exposure, sensitivity and adaptive capacity. For Exposure, we considered the elevation (contour), watershed, waterway, roads, railways and airport thematic layers. For Sensitivity, the built-up area, industry, manages (?) system such as farmland and land use/cover map from GIS data were used. To examine the adaptive capacity, we addressed the natural vegetation layer, economic points and infrastructure. Results show that the center and northern part of the city are highly and extremely vulnerable due to industry and high socio-economic activities when compared with the southern part of the city. We divided the whole city into 5 types of vulnerability: Resilient 2.24 %, at risk 13.20 %, vulnerable 46.15 %, highly vulnerable 7.26 % and extremely vulnerable 31.15 %, in terms of the city area percentage. The vegetation area (50.51 %) has the maximum vulnerable area and the vulnerable class covers the maximum area (46.15 %) of the city. All this information is very indispensable and can be used to address management issues, such as resource prioritization and optimization.
Загружаем данные из библиотечной системы...
Ключевые слова
+
ERRATUM: DYNAMIC ANALYSIS OF OPTICAL CELL TRAPPING IN THE RAY OPTICS REGIME
стр.759-760
Klykov S.S., Fedosov I.V., Tuchin V.V.
In this additional part of the original paper [1], revised calculations and corrected equations are presented. Also some conclusions from the original paper are revised and discussed briefly.
Загружаем данные из библиотечной системы...
Ключевые слова
