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Optical fiber sensors for measurement strain and vibration
Mikel, Břetislav ; Helán, R. ; Buchta, Zdeněk ; Holík, M. ; Jelínek, Michal ; Číp, Ondřej
We present optical fiber sensors to measurement strain and vibration. The sensors are based on fiber Bragg gratings (FBG). We prepared construction of strain sensors with respect to its implementation on the outer surface of concrete structures and with compensation of potential temperature drifts. These sensors are projected with look forward to maximal elongation and strength which can be applied to the sensor. Each sensor contains two optical fibers with FBGs. One FBG is glued into the sensor in points of fixation which are in the line with mounting holes. This FBG is prestressed to half of measurement range, than the stretching and pressing can be measured simultaneously by one FBG. The second FBG is placed inside the sensor without fixation to measure temperature drifts. The sensor can be used to structure health monitoring.
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Optical fiber sensors for nuclear power plants
Mikel, Břetislav
We present new optical fiber sensors based on fiber Bragg gratings to measurement length, pressure, tension, temperature and vibration (angle). We present our first measurement from our primary application in the nuclear power plant. We measured containment shape deformation in the nuclear power plant Temelin, Czech Republic. We realized complete control system including special sensors and the unique method of placing sensors to containment. The results are presented.
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Optical fiber senzors to measurement length, pressure, tension, temperature and vibration
Mikel, Břetislav
We present new optical fiber sensors based on fiber Bragg gratings to measurement length, pressure, tension, temperature and vibration. We developed systems to monitoring several types of sensors. Measurement of length, tension, pressure and temperature is realized on the same principle of measurement spectral properties of sensors. We used optical filter based system to monitoring optical spectrum reflected from sensors in our system. Sensor with tilted fiber Bragg grating in tapered optical fiber we used to monitoring vibration. This ghost mode reflected from tilted fiber Bragg grating is recoupled into the fiber core in tapered prat of fiber. The measurement system can measure only optical power.
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Fiber gratings to nuclear power plant Temelin and theirs calibration by laser interferometer
Mikel, Břetislav
We present application of the optical fiber sensors to measurement the shape deformation of the containment of the nuclear power station Temelin. The presented method can be used to measure any concrete buildings. To prepare optical fiber sensors we developed method of measurement of fiber Bragg gratings (FBG) stretching by laser interferometer. We are oriented to research, development and to methodology of the production and application of FBGs. The elongation of FBGs can calculated from frequency drift of the Bragg resonance wavelength and from the change of the grating period during stretching.
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