Optoelectronics, Instrumentation and Data Processing (v.54, #4)

An algorithm is proposed to estimate the node coordinates of deformed lattices of quasiperiodic textures with subpixel accuracy. The algorithm consists of two steps. In the first step, the frequency and initial phase vectors of a polyharmonic brightness function model are calculated from the characteristics of spectral outliers of image fragments. The obtained estimates are used to determine the coordinates of the nodes of the local lattice. In the second step, the local lattices are combined into a global lattice for the entire image of the quasi-periodic texture. Using high-accuracy estimates of model parameters from small image fragments ensures stable operation of the algorithm for significant deformations of the lattice and sub-pixel accuracy in estimating the coordinates of its nodes. Results of computer simulation and processing of real halftone images of quasiperiodic textures are given demonstrating the effectiveness of the proposed algorithm.
Keywords: subpixel accuracy of estimation; quasiperiodic texture; node coordinates of deformed lattice; polyharmonic model; spectral outliers

The errors of estimates of the size, depth, and magnetization of a local source of a simply shaped magnetic anomaly are studied by means of a comprehensive analysis of magnetic survey performed at different altitudes. Numerical simulations show that the values of magnetic induction induced by the presence of a magnetic source measured at different altitudes provide a more accurate estimate of some parameters of this source than the measurements performed at one altitude.
Keywords: magnetic anomaly; inverse problems of magnetic survey; UAV

Compression of Geometric Data with the Use of Perturbation Functions by S. I. Vyatkin; B. S. Dolgovesov (334-339).
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.
Keywords: perturbation functions; theoretic multiple operations; compression of geometric data

Selective Segmentation of the Shallow Electrical Profiling Data by A. G. Zlobina; I. V. Zhurbin; O. M. Nemtsova (340-347).
A method for selective segmentation that correctly recovers the boundaries of objects in the plan and estimates the depth range is proposed. This method requires that the electrical exploration data are processed: shallow electrical profiling and vector images of the main directions of changes in the resistance of the medium. An object boundary is estimated on the basis of a fuzzy clustering algorithm (fuzzy c-means), adapted for analyzing multispacing electrical profiling. The depth range of an object in soil is estimated on the basis of applying a scalar product function to vector images of the main directions, adjacent in depth. The effectiveness of this method is confirmed by computer simulation and an example of data processing of the field experiment on an archeological site, which is a medieval fortified settlement.
Keywords: electrical profiling; computer simulation; fuzzy c-means; vector images of the main directions; selective segmentation methods; object boundary; depth range

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.
Keywords: space-time processing; multiposition system; radiometers; radio images; mutual orientation; trajectory processing

Amplitude-Hyperbolic Method of Passive Location of a Radiation Source by Yu. G. Bulychev; I. G. Nasenkov; A. V. Yachmenev (355-360).
A new method for ranging and locating a radiation source is proposed for a two-position system that detects an amplitude and difference of instances at which a wave arrives at a receiving position. Equations that make it possible to study the procedural error and accuracy characteristics of the method for various observation conditions and the results of a computational experiment are presented. Recommendations on applying this method are given.
Keywords: goniometric energy method; energy method; amplitude-hyperbolic method; two-position amplitude-hyperbolic system; wave amplitude; wave time delay

Speech Signal Segmentation into Vocalized and Unvocalized Segments on the Basis of Simultaneous Masking by A. A. Konev; R. V. Meshcheryakov; E. Yu. Kostyuchenko (361-366).
This paper touches upon a model of simultaneous acoustic masking, which detects speech signal components perceived by a human’s auditory system. A simultaneous masking algorithm on the basis of this model is proposed. It is shown that, after simultaneous masking, a signal becomes a binary structure that reflects the harmonic structure of a vocalized sequence. It is experimentally proven that this structure can be used to detect key speech segments (from the standpoint of perception by an auditory system). This structure serves as a basis for an algorithm of high-quality segmentation of a speech signal into vocalized and unvocalized segments, which does not require learning before use. The joint use of the algorithms for simultaneous masking and speech signal segmentation is tested, and their performance is evaluated.
Keywords: speech signal; simultaneous masking; speech signal segmentation; vocalized and unvocalized segments

This paper proposes and theoretically justifies a method for quick contactless measurement of specific electric constant and dielectric and magnetic constants of materials by means of pulse probing of a controlled surface. An electromagnetic pulse reflected from a controlled object carries information in its spectral composition on measured parameters that can be determined according to the proposed technique.
Keywords: electromagnetic parameters; pulse probing; spectral composition; quick control

A tunable (in terms of the angle of convergence of intersecting light beams) two-beam interferometer with fixed mirrors and a fixed photosensitive element is considered. The photosensitive element is based on a symmetric beam-splitter unit where tuning of the interference pattern period is ensured by only one type of motion: interferometer rotation with respect to the motionless source of the collimated light beam. It is demonstrated that the period can be controlled in this way for convergence angles from 30 to 180° for beams with diameters of 10% or more of the beam-splitter unit length. In this region, the greatest width of the range of convergence angle tuning can exceed 40°, and the admissible beam diameter approaches 40% of the beam-splitter unit length. Comparisons with a similar interferometer based on a beam-splitter cube are performed, and possible areas of application of the considered interferometer are determined.
Keywords: two-beam interferometer; symmetric beam-splitter unit; fixed mirrors; fixed photosensitive element; rotational tuning of the convergence angle; holographic diffraction grating

Compact Amplitude Electro-Optic Modulator Based on Chromophore-Containing Polyimides by S. L. Mikerin; A. I. Plekhanov; A. E. Simanchuk; A. V. Yakimanskii; A. A. Martynenkov; N. A. Valisheva (385-389).
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.
Keywords: electro-optic polymers; microwave photonics; electro-optic modulator; Mach–Zehnder interferometer

Method of Calibration of a Laser-Based Galvanometric Scanning System with Submicron Resolution by V. P. Bessmeltsev; N. V. Goloshevsky; V. V. Kasterov; Ya. A. Kipriyanov; K. K. Smirnov (390-396).
A method used for calibration of scanning modules on the basis of galvanometric deflectors is considered. The method is based on an iterative two-step algorithm of processing of the profilometry map of the test writing of the calibrated module. It is demonstrated that high accuracy and robustness of determining the coordinates of the reference points of the test writing can be obtained by means of finding the approximate positions of such points and identifying the fragment in the vicinity of these points at the first step and searching for the exact values of the coordinates by the correlation method at the second step. The use of this method and a simple algorithm of piecewise-planar interpolation offers a possibility of laser beam positioning with a relative error of 10−5 from the writing field.
Keywords: laser micromachining; galvanometric deflectors; complementary scanning systems; cross-correlation method

Optoelectronic System for Studying Nanodisplacements of Moving MEMS Elements by E. G. Kostsov; A. I. Skurlatov; A. M. Shcherbachenko (397-404).
An experimental structure of an optoelectronic system for contactless measurements of micro- and nanodisplacements of moving MEMS elements is considered. The system is based on a heterodyne interferometer with a frequency-stabilized He–Ne laser and an acousto-optical modulator of laser radiation. A resolution of less than 1 nm in terms of the moving element displacement is reached in experiments by applying voltage pulses with amplitudes up to 1 V on the MEMS structure; moreover, the displacement amplitude is found to be a linear function of the control voltage with sensitivity of 100–200 nm/V. No hysteresis is observed on the curve plotted in the coordinates of the element location and control voltage.
Keywords: acousto-optical modulator of laser radiation; moving MEMS element

The photo extraction of rubidium atoms from the bulk of a photonic crystal has been investigated. It has been found that in the case of irradiation of the crystal in the stop band where the desorbing light does not penetrate deeply, the separation of atoms occurs practically from its surface, so that the density of desorbed atoms in the cell decreases only exponentially. In the case of irradiation of the crystal outside the stop band, the bulk of the crystal is irradiated almost completely. In this connection, the exponential decrease in the density of atoms in the cell is replaced by its relatively slow reduction of diffusion nature. The bulk diffusion coefficient of rubidium atoms in the photonic crystal was measured to be 2 · 10−8 cm2/s.
Keywords: collision of atoms with surface; adsorption time; diffusion; diffusion coefficient of atoms in photonic crystal

Channels with and without memory are compared using the simplest Gaussian noise distribution model. It is shown that both channels have similar dependences of the capacity on the average signal power. At the same time, the optimal input alphabet for the channel with memory changes. The applicability of the model with nonlinear memory to the QPSK communication line with a periodic dispersion compensation is demonstrated numerically.
Keywords: optical fiber communication lines; capacity; nonlinear noise; channel with memory; Shannon limit

The formation and dynamics of excitations in an atomic or molecular nano chain of a helical shape are studied. The dipole-dipole interaction between the circular polarizations of the optical transitions of neighboring molecules is taken into account. The derived Bloch equations are solved in a continuum approximation using the Frenet–Serret coordinate system. Solutions are obtained that describe the formation of stable localized structures (solitons) due to the curvature of the chain, which can have a critical influence on the luminescent properties of the chiral medium.
Keywords: nanomaterials; helical structures; excitons; solitons