Oleg V. Kirichenko

Recovering physical fields with a two-dimensional fiber-optics measurement grid

A tomographic fiber-optics grid can be used to record two-dimensional field patterns. The structure of the grid is described, and a processing algorithm has been tested, which reduces the number of fiber lines required by a factor of 4. An experimental model has been tested successfully in the recovery of the two-dimensional transverse vibration pattern at the surface of a ships fuel tank.

Fiber optic measuring network for scalar and vector physical field investigation

The fiber optic measuring network for scalar and vector physical field investigation is studied. The special method of network signals processing which allows minimizing the number of measuring lines is suggested. It is shown that by choosing of measuring line construction and trajectory one can reconstruct the distributions of scalar field amplitudes or distributions of vector field Decarts components or distributions of square of vector field gradient.

Fiber optic sensors for vibration registration by means of interferometry and speckle interferometry methods

We describe the physical principles involved in constructing distributed and remote fiber-optic sensors for vibration and displacement registration on the basis of interferometry and speckle- interferometry methods. Experimental models of such sensors were made and tested. The results show a good coincidence with theoretical predictions.

Investigation of physical fields by using two dimensional fiber - optic measuring network

The possibility of the development of fiber-optics measurement network for reconstruction of 2D distributions of physical fields is shown. The structure of the network is developed and special algorithm of its signal processing allowing in four time to decrease the number of necessary fiber measurement lines is tested. Experimental model of the network is successfully used for reconstruction of intensity distribution of transversal vibrations of ship fuel tank surface.

Neural-like holographic information system for processing of optical signals

The main advantages of a neural networks are the flexibility of architecture and ability to training. It allows to perform data processing even when the processing procedure can not be present by the known function. The neural networks based on optical elements allow real time operation rather than electronic neural networks. We offered system, based on neural networks, capabling to solve a broad class of heterogeneous problems and adapting to input information flow. The system are based on neural networks of two types: (1) a single-pass network of perceptron type and (2) recognize network of Hopfield network type. The neural network of the type (1) is realized by holographic scheme and experimental checked when processing the signals fiber- optic measuring network.

Tomography methods of vector fields investigation

A problem of tomography reconstruction of vector physical fields by using the sets of contour integrals from a vector projection and from projection of a vector derivative with respect to direction is investigated. A necessity of using nonrectilinear measuring lines for tomography reconstruction of vector field parameters distribution is shown. If the measuring line output signal is proportional to integral from projection of a researched vector it is possible to use the measuring line in the form of a narrow loop and the decision of a problem can be received by use of integral theorems. If the measuring line output signal is proportional to integral from projection of a vector derivative with respect to direction (e.g. problem of deformed two-dimensional object), it is possible to use the measuring line of step form and potential component of a vector field can be reconstructed. The method can be widely applied to research distribution of an electromagnetic, deforming and other vector fields inside elements of technical and technological objects constructions and also can become a basis of systems of vector physical fields monitoring.

Method of single-fiber multimode interferometer speckle signal processing

A method of correlation processing of speckle-signals formed by multimode interferometer is theoretically and experimentally investigated. The method permits to transform modulation of a speckle-pattern to optical or electrical signal, which linear depends on correlation coefficient of reference and current speckle patterns. The functional dependence of correlation coefficient from value of lengthening of interferometer is studied. The results allow to perform quantitative measurements of lengthening value. Mathematical algorithm enabling to define a sign of lengthening is developed. A correlated change of local areas of speckle-patterns formed by multimode fiber is discovered. It is developed an analog computing system which can perform the correlation measurements in real time in wide bandwidth. Optical and electrical circuits are made on standard components, that makes the method suitable, for example, for industrial use.

Self-training neural network model for tomography data processing

In this paper we present self-training two-layer neural network model for tomography data processing. This model allows us to reconstruct physical field parameters distribution by use of tomography integral data.

New methods of multimode fiber interferometer signal processing

New methods of multimode fiber interferometers signal processing are suggested. For scheme of single fiber multimode interferometers with two excited modes, the method based on using of special fiber unit is developed. This unit provides the modes interaction and further sum optical field filtering. As a result the amplitude of output signal is modulated by external influence on interferometer. The stabilization of interferometer sensitivity is achieved by using additional special modulation of output signal. For scheme of single fiber multimode interferometers with excitation of wide mode spectrum, the signal of intermode interference is registered by photodiode matrix and then special electronic unit performs correlation processing. For elimination of temperature destabilization, the registered signal is adopted to multimode interferometers optical signal temperature changes. The achieved parameters for double mode scheme: temporary stability--0.6% per hour, sensitivity to interferometer length deviations--3,2 nm; for multimode scheme: temperature stability--(0.5%)/(K), temporary nonstability--0.2% per hour, sensitivity to interferometer length deviations--20 nm, dynamic range--35 dB.

Fiber-optic measurement grid for registration of the parameters of vibrational processes

We propose a design for a fiber-optic measurement grid for registration of the vibrational parameters of various structural elements. We consider the principle of operation and give an analysis of the output signal of the measurement grid, consisting of quasidistributed fiber-optic sensors of the integrating type. We also describe and experimentally study a model for a grid for registration of the vibrational intensity distribution for the surface of the test object.