The paper describes the implementation of a fiber-optic single-channel vibration sensor built on the basis of two fiber Bragg gratings, a broadband source, a photodetector and a sound card of a computer used as an ADC
Keywords: vibration, fiber optic sensor, fiber Bragg grating, Fourier transform
The complexity and high cost of multiplexing optical fiber sensors is still the main limitation for the widespread introduction of sensory systems, both distributed and quasi-distributed, and point-like. The article proposes a new multiplexing method that takes advantage of both broadband and two-frequency radio-photon multiplexing systems. The simplest broadband radiator is taken from the first, but a complicated and expensive system of spectrometry is not used to determine the central wavelength of fiber Bragg gratings. From the second, a recording system is used at the beat frequency between two components, but an expensive system for generating two- and polyharmonic probing systems is not used. The multiplexing parameter is determined by the frequency of separation between the transparency windows of a fiber Bragg grating, for example, with two phase π-shifts, which differs by a certain value for each of the sensors. The mechanism of modeling of gratings of the specified type is given, in principle the possibility of multiplexing of various number of sensors is shown. When using sensor networks built on the basis of passive optical, the number of multiplexed sensors can reach 256, with all sensors having the same Bragg wave of the wave, and can be combined into tree, bus and other topologies.
Keywords: fiber Bragg grating, phase inhomogeneity, fiber optic sensor, multiplexing, transparency window, frequency difference between transparency windows, beat frequency
The present article is devoted to development and a research of the distributed fiber systems of aero acoustic control of parameters of an air-gas stream on a cut of a nozzle of turbomachines. The main emphasis is placed on development and to a research of the distributed fiber systems on the basis of control methods the using multiplexed fiber-optical sensors of control of parameters of an air-gas stream on a cut of a nozzle of the turbomachines using advantages of optical methods of information transfer and the device for his realization. The principles of creation of the complex systems of aero acoustic cartography complemented with methods and measuring instruments of gasdynamic parameters of a stream in a flowing part and on a cut of a nozzle of the turbomachines directed to increase in informational content and level of algorithmization of nondestructive control of a condition of working shovels and providing data acquisition in the conditions of parametrical and structural uncertainty of an air-gas stream as on controlled internal sections of a flowing part, and on output section on a turbomachine cut are defined. Problems of placement of points of control and restoration of spatial distribution of the field of measurements in discrete set of points separately are considered. Restoration of the acoustic field of turbomachines is implemented according to measurements at the exit of WATERS, only using statistical approach. Restoration of the field is presented in the form of continuous functions of spatial coordinates by results of measurement in discrete set of points in the presence of aprioristic information on properties of the measured fields. Statistical approaches for determination of coordinates of sensors and an error of restoration on the example of one model problem of control of the field of the radiation created by the continuous exclusive radiator are used. Results of calculations show that existence of correlation between coefficients of decomposition of the field of radiation on functions, leads to reduction, necessary for achievement of the set accuracy of restoration of number of sensors.
Keywords: distributed fiber systems, аero acoustic control, acoustic field, process simulation, recovery
A variant of the solution of the problem of characterization of a resonant Fano contour in optical biosensors of refractometric type based on ring fiber Bragg gratings with pi-shift is presented. The use of biosensors of this type makes it possible to increase the sensitivity of detecting changes in the refractive index of the medium under investigation to the level (1-2) x10-9 RIU. These sensitivity values are achieved due to the formation in the lattice of a high-quality Fano resonance with a loop width at half-height equal to 1-5 pm. However, the possibility of obtaining a significant gain in metrological characteristics on the one hand, poses the problem of characterizing such narrow-band resonances on the other, since the existing optical spectrum analyzers do not have the appropriate resolution. To solve this problem, we propose a radio-photon method of three-frequency probing of a high-band and an asymmetric Fano contour by symmetric amplitude-modulated radiation with side-amplitude components unbalanced in amplitude. In contrast to the previously used for solving similar problems of two-frequency symmetric sounding with equal amplitudes of side components and a suppressed carrier, we have uniquely determined the central frequency, the maximum amplitude and Q of the Fano circuits, as well as the possibility of greatly simplifying the technique of collecting information on their parameters. The article consists of two parts, which consistently reflect the posing of modeling problems and discussing its results with confirmation of the results of physical experiments.
Keywords: optical biosensor, refractometry, Bragg fiber grating, phase pi-shift, Bragg annular fiber grating with phase pi-shift, Fano resonance, refractive index change, sensitivity, resolving power, radiophoton measurement methods, two-frequency symmetric balance
An overview of the basic schemes, characteristics, and directions of development of microwave photonics systems is presented in this paper in terms of requirements defining the parameters of external amplitude-phase modulation of laser radiation as a key process for the formation of radio frequency signals in the optical range for systems with polarization multiplexing of polyharmonic signals.
Keywords: microwave photonics; external amplitude and phase modulation, optical generation of radio frequency signals; generation of poly-harmonic optical signals with microwave frequency components
The article presents the results of simulation of the microstrip microwave structure of the ring configuration, which, by analogy with the fiber-optic prototype, embodies the principle of Fano resonance formation. This type of resonance is characterized by the asymmetry of the shape and has a narrower resonance than the classical Gaussian and Lorentzian forms.
Keywords: Ring resonator, Bragg reflection, Fano resonance, phase shift
Paper deals with the analysis and synthesis of geographically distributed systems for storage of hazardous substances from the environmental safety position. Particular attention is paid to the information layer to ensure environmental safety (ES) of these systems, which operates on the results of the processing of regulatory documents, environmental monitoring data, analytical reports, etc. Its operation is based on a system of specialized automated workplaces (AWP), each of which generates a plurality of projections and calculations in order to provide ES, using information on three levels of detail: the physical, technological and logical. The structures of mathematical, informationtion, software and hardware provision of AWP are discussed. It is shown that the proposed AWP structure can be used in the design of the various systems for storage of hazardous substances and is aimed to provide ES in their operation.
Keywords: geographically distributed storage systems, hazardous materials, environmental security, information maintenance, environmental specialists, workstation
From the standpoint of environmental safety paper deals with the analysis and synthesis of geographically distributed systems for storage of hazardous substances. The main attention is paid to the technical maintenance of ecological safety of these systems which is determined by the layer of tool control system (TCS) in ecological situation monitoring channels, storage of hazardous substances and protection parameters of perimeter storage. Operation of TCS relies on the use of fiber-optic sensors based on fiber Bragg gratings in each of said channels and their methods of polyharmonic probing. Defined principles of joint measurement of temperature and pressure as the main storage options, optical absorption measurements of gas concentrations using remote multicomponent fiber optic infrared analyzer for monitoring the environmental situation are discussed. The information about the construction of storage areas perimeter security systems sensors are given. It is shown that the proposed TCS structure can be used in the design of the various systems of hazardous substances storage and is aimed at addressing issues of environmental safety in their operation.
Keywords: geographically distributed storage systems, hazardous materials, environmental security, technical support, fiber Bragg grating, measurement of temperature and pressure, multi-fiber optical infrared gas analyzer
The principles of intelligent node of electroengine - brush are discussed. Into the brush an optical fiber sensor of wear and temperature on the basis of serial low reflection fiber Bragg gratings (FBG) is embedded. In contrast to existing, developed sensors are complexed and are able to simultaneously measure the temperature of the shift of the central wavelength of laser radiation reflected by the FBG, the amount of wear by means of registration the change in the length of the FBG arrays. Analysis of the signal reflected from the FBG allows you to define the parameters of the engine speed, temperature changes - the state of brush-collector unit. At a resolution of the interrogator in the wavelength about 2 ps the temperature sensor has resolution 0,2 ° C. Measurement error values of wear sensor, determined by the stability of the amplitude parameters of laser radiation, are near tenth part of micrometer.
Keywords: friction, complexed fiber optic sensor, fiber Bragg grating, wear, temperature,electroengine, smart brush, rotation speed