The possibility of detection of methane using fiber-optical sensor with ZnO-SnO2-Fe2O3 photocatalyst was demonstrated. Photocatalytic composite sensor element was prepared by non-isothermal polymer-salt method from solutions of inorganic metal salts and polyvinylpyrrolidone. Optical detection is carrying out by Bragg diffraction grating of fiber-optical sensor at the temperature variations during photocatalytic methane oxidation.

Technique for the detection of gaseous hydrocarbons using a remotely interrogated fiber-optic sensor with the oxide photocatalyst was demonstrated. This specially developed ZnO–SnO2–Fe2O3 material can generate reactive oxygen species when exposed to light with wavelength λex = 405 nm. Volatile hydrocarbons vapors detection in air with volume concentration from 6 to 50

The effect of γ-irradiation on optical losses at a wavelength of 1.31 to 1.55 μm in multimode quartz fibers with a core doped with 20 mol % GeO2 is considered. Germanium oxygen-deficient centers in the core material are the main reason for the low radiation resistance of such optical fibers. The elimination of these defects in the MCVD preform technology reduces the radiation-induced attenuation in germanosilicate light guides to a level close to that of light guides with a pure quartz glass core. The increase in optical losses induced by radiation in the studied fibers is largely due to the contribution of Rayleigh scattering.

The paper discusses the problem of temperature drift compensation in a fiber-optic gyroscope, using a number of temperature sensors distributed along the gyroscope coil. An algorithm is proposed for processing the sensors’ data in the form of weighted sum of temperature values and its derivative. The results of the proposed algorithm comparison with an algorithm that uses averaged readings of sensors are presented. It is shown that the proposed algorithm increases the compensation accuracy up to 50%.

The central wavelength stability of the erbium-doped fiber source (EDFS) is one of the most significant parameters to provide the accurate operation of high-accuracy fiber-optic gyroscopes (FOGs). In this paper, the method of stabilization of the EDFS as a part of the FOG is presented. The main advantage of this method is the possibility of quick and simple matching of temperature-compensating spectral filters by changing the pump ratio without modifications of the optical scheme. It allows to obtain the world-class stability of the central wavelength of the EDFS as a component of spectral selectivity devices and provides the constant value of the optical power of the output light. The proposed method makes it possible to compensate the spectral characteristics of FOG, achieving the stability of output light central wavelength about 0.7 ppm/°C. Also, a method of real-time stabilization of the central wavelength of the output light (OL) with constant optical power is proposed. The temperature stability of the EDFS central wavelength as a component of the FOG was obtained at 0.32 ppm/°C.

Abstract The stability of the central wavelength of the erbium‐doped fibre source (EDFS) is one of the most important parameters to ensure the accurate operation of navigation systems based on high‐accuracy fibre optic gyroscopes (FOGs). Herein, the method of stabilisation of the EDFS as a part of the FOG is presented. The main advantage of this method is the possibility of quick and simple matching of temperature‐compensating spectral filters by changing the pump ratio without modifying the optic scheme. The EDFS optic scheme is based on the double‐pass bidirectional pumping configuration. This makes it possible to obtain the world‐class stability of the central wavelength of the EDFS as a component of different devices with the spectral selectivity and set the constant value of the optic power of the output light (OL). Also, this is the first study into the dependence of the temperature coefficient of the central wavelength on the pump ratio. The proposed method allows compensating the spectral characteristics of the FOG, achieving the OL central wavelength stability around 0.7 ppm/°C and the FOG scale factor stability around 0.73 ppm/°C.

The surface relief of blanks and silica glass fibers is studied by atomic force microscopy. The temperature change during free cooling is recorded using an infrared pyrometer. The results of the measurements of the roughness of the blank and fiber could indicate the effect of the cooling time of the quartz glass (QG) on the morphology of its surface.

Currently, the solution for the problem of temperature measurement of the gas phase of combustion products inside the combustion chambers of gas turbine engines is still in progress. Conventional thermocouples, which are the industry standard, are intrusive and provide spatially and temporally averaged data. In this work, a spectral system for the temperature measurement of gas flow inside the combustion chamber has been developed. The system is based on the method of multi-wave pyrometry of soot in the visible optical range and comprises a multispectral sensor-on-chip solution. Field tests on the gas turbine engine confirmed that the presented system allows measuring temperature in the range from 810 to 1120 degrees C with a measurement error of 3%. (C) 2019 Elsevier Ltd. All rights reserved.

This work presents the fluorescent method of meat bacterial contamination control based on the influence of E. coli metabolites on the fluorescence spectrum of meat surface. The experiment revealed that proposed method allows detecting bacterial contamination with concentrations above 106 CFU/cm2 on a beef surface.

In the fabrication of single-mode germanosilicate light guides, we studied how a reducing atmosphere in the high-temperature compression process of fiber preforms in a modified chemical vapor deposition process affects the photorefractive properties of the light guides. The results indicate an increase in photorefractivity and a decrease in the fiber drawing temperature with additional doping of the core of the light guide with fluorine. (C) 2017 Optical Society of America

It is established that silica optical fibers (SOF) strength increases twice as environment moisture decrease down to water vapors pressure of 10(-2) Pa. Further decrease of moisture doesn't influence their strength. Highly-stressed SOF fracture periods of up to 10(-3) sec have been found to be controlled by water vapor pressure. SOF treatment by HCl solution increases their strength by 7% and their static fatigue 10 times.

In this paper, we discuss how the drawing temperature of quartz light guides with germanosilicate cores and outer borosilicate cladding affects their strength and optical losses. The low-viscosity cladding of a light guide allows the drawing temperature to be decreased to 1950 degrees C, which, in turn, leads to increased strength and helps reduce excessive optical losses. (C) 2017 Optical Society of America

This paper discusses how hydrogen-isotope doping of a single-mode W-type fiber lightguide with fluorosilicate cladding affects its additional optical losses under bending of the fiber and γ irradiation. It is established that introducing stable OH− and OD− groups into the core of a lightguide fabricated by modified chemical vapor deposition reduces its optical losses when it is bent but does not increase the radiation–optical stability.

The properties of anisotropic single-mode fiber lightguides with an elliptical highly doped germanium core and elliptical fluorine-doped cladding have been investigated. When the difference of the refractive indices of the core and the cladding equals 0.033 and the ratio of the axes of the core is about 2, the birefringence is about 0.00037. The fabricated lightguides, despite the differential optical losses of the orthogonal modes to radiation leakage, are distinguished by a low level of polarization stability. The degree to which the radiation remains polarized in them (approximate to 0.003 m(-1)) is two orders of magnitude worse than in commercially produced lightguides. This is probably caused by local microstrain of the low-viscosity glass of the core. (C) 2014 Optical Society of America.

It is established that the strength of as-drawn silica fibers exhibits a 15% drop for about an hour after drawing. The nature of this phenomenon is related to a change in the content of moisture in a polymer coating of the fiber. Based on analysis of the observed phenomenon, it is recommended to modify the process of silica-fiber drawing.

The results of work on the stabilization of the wall thickness of quartz tubes by means of external vapor-phase deposition during high-temperature hydrolysis of silicon tetrachloride are presented. The technological parameters of deposition and sintering of a porous layer are determined. Defect-free layers of glass of thickness greater than 0.2 mm with the possibility of lowering the circumferential thickness variation of the tubes from 0.2 to 0.05 mm are obtained.

Diagnostics of a functional condition of an organism of athletes is based on methods of cardiological monitoring. Respiratory methods of diagnostics in sports medicine can become important addition in the prevention of development of cardiovascular diseases and need additional researches. In an assessment of a functional condition of athletes authors of article allocate a particular interest for remote methods of on-line diagnostics. In article possibilities of application of remote respiratory monitoring in functional diagnostics of athletes and the people which work is connected with raised loads of an organism are considered. Respiratory monitoring is applied to carry out microminiature accelerometers. The method of mobile cellular systems is offered for on-line monitoring.

This paper presents the results of recording Bragg gratings in a birefringent optical fiber having increased photosensitivity with a single 20-ns pulse from a KrF excimer laser. A description is given of a stand for recording fiber Bragg gratings by the phase-mask method and of experimentally produced Bragg gratings in a birefringent optical fiber with elliptical stress cladding, having an efficiency greater than 2% and a reflection spectrum about 0.1 nm wide at half-height.

This paper discusses how the damping at wavelength 1.55 mu m depends on various factors for anisotropic single-mode lightguides with boron germanosilicate elliptical cladding. It is shown that the refractive index of this cladding in the preform has a substantial effect on the optical losses of the lightguides. The thickness of the cladding that isolates the core from the boron-containing glass of the elliptical cladding is optimized. The optical losses to Rayleigh scattering are reduced by doping the core with small additives of moisture. For a lightguide with a glass-fiber diameter of 125 mu m in a two-layer polymeric coating, an optical loss level equal to 0.5 dB/km is achieved, with a polarization maintenance of 5 x 10(-6) m(-1). (C) 2012 Optical Society of America.