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1

Rotation and twist measurement using tilted fibre Bragg gratings

Kisała P., Skorupski K., Cięszczyk S., Panas P., Klimek J.

Metrology and Measurement Systems

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2018

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Vol. 25, nr 3

429--440

EN

The paper presents a method of measuring the angle of rotation and twist using a tilted fibre Bragg grating (TFBG) periodic structure with a tilt angle of 6°, written into a single-mode optical fibre. It has been shown that the rotation of the sensor by 180° causes a change in the transmission coefficient from 0.5 to 0.84 at a wavelength of 1541.2 nm. As a result of measurements it was determined that the highest sensitivity can be obtained for angles from 30° to 70° in relation to the basic orientation. The change in the transmission spectrum occurs for cladding modes that change their intensity with the change in the polarization of light propagating through the grating. The same structure can also be used to measure the twist angle. The possibility of obtaining a TFBG twist by 200° over a length of 10 mm has been proved. This makes it possible to monitor both the angle of rotation and the twist of an optical fibre with the fabricated TFBG.

2

Power modulated temperature sensor with inscribed fibre Bragg gratings

Mądry M., Markowski K., Jędrzejewski K., Bereś-Pawlik E.

Opto-Electronics Review

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2016

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Vol. 24, No. 4

183--190

EN

The Fibre Bragg Grating (FBG) based temperature optical sensor has been designed and demonstrated. FBGs have been modelled and fabricated so as to convert the Bragg wavelength shift into the intensity domain. The main experimental setup consists of a filtering FBG and two scanning FBGs, respectively, left and right scanning FBG, whereby scanning FBGs are symmetrically located on the slopes of the filtering FBG. Such an approach allows for the modulation of power for the propagating optical signal depending on the ambient temperature at the scanning FBG location. A positive or negative change of power is determined by the spectral response of the FBG. Experimental research of the scanning FBGs’ sensitivities emphasized that the key issue is the filtering FBG. A different level of sensitivity could be achieved due to the spectral characteristic of the filtering FBG. Omitting advanced and high-cost devices, the FBG-based temperature sensor is presented. The FBG-based sensor setup could yield resolution of 1°C for the range of temperature 0.5°C to 52.5°C. The experimental study has been performed as a base for an easy-placed sensor system to monitor external parameters in real environment.

3

W pełni optyczny przełącznik wykorzystujący jednorodne światłowodowe siatki Bragga

Kisała P., Klimek J., Skorupski K.

Przegląd Elektrotechniczny

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2015

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R. 91, nr 11

266-270

PL

W artykule zaprezentowano koncepcję całkowicie optycznego przełącznika opartego na dwóch jednorodnych światłowodowych siatkach Bragga oraz światłowodach domieszkowanych pierwiastkami ziem rzadkich. Przedstawiono model układu wykazującego właściwości bistabilne, warunkujące przełączanie w pełni optyczne. Dokonano również analizy podstawowych właściwości zaproponowanego układu przełącznika optycznego w oparciu o uzyskane charakterystyki przetwarzania.

EN

In this article the concept of all-optical switch based on two uniform fiber Bragg gratings and rare earth elements doped optical fibers have been presented. A model showing the bistable properties, conditioning all-optical switching have been also submitted. The basic properties of the proposed optical switch based on processing characteristics have been analyzed.

4

Measurement of the maximum value of non-uniform strain using a temperature-insensitive fibre Bragg grating method

Kisała P.

Opto-Electronics Review

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2013

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Vol. 21, No. 3

293-302

EN

This paper presents an optoelectronic method for measuring the maximum value of non-uniformly distributed strain at varying temperature. Use of conjugate a gradient algorithm and a sensor model makes it possible to determine the maximum non-uniform strain value and the temperature at which the measurement is performed. The described sensor system enables the maximum strain value to be determined with a linear resolution of 0.003 m. A specially designed measurement system is proposed to verify the plausibility of using uniform fibre Bragg gratings for the simultaneous measurement of two quantities. The possibility of using the spectrum of two grating sensors to determine the maximum value of a non-uniform distribution of strain and temperature values is demonstrated.

5

Metrological conditions of strain measurement optoelectronic method by the use of the fibre Bragg gratings

Kisała P.

Metrology and Measurement Systems

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2012

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Vol. 19, nr 3

471-480

EN

This article presents a linear strain measurement method insensitive to temperature variations and using fibre Bragg gratings. Two Bragg gratings were applied with periods selected to obtain partial coverage of their spectrum characteristics. One of the gratings was subjected to a tension strength. Placing both gratings in one thermal chamber allowed - through ensuring the same thermal conditions - to obtain insensitivity of the entire scheme to temperature variations. The gratings were recorded on the same optical fibre and reacted to temperature variations in the same degree. Value of strain was indicated based on the transmission spectrum characteristic of two grating schemes. The use of transmission, not reflectance, characteristics of the gratings allowed for a direct measurement of the spectrum, without having to use a coupler or optical circulators, and at the same time, this allowed to simplify the strain detection scheme. We proposed applying the continuous wavelet transform with characteristics of the spectrum scheme of two gratings for improvement of static properties. Especially, the thermal linearity and stability of the sensor was improved. For a strain range up to 750 με, the non-linearity error of processing characteristic obtained was 0.45%. Thermal stability of the scheme proposed was defined as relative sensitivity of the power to temperature variations. The mean value of such relative sensitivity of the scheme proposed in the temperature scope of 21°C-95°C, amounted to 0.195.

6

Generation of a zone chirp in uniform Bragg grating as a way of obtaining double functionality of a sensor

Kisała P.

Metrology and Measurement Systems

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2012

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Vol. 19, nr 4

727-738

EN

This paper presents a method of using a sensor with uniform Bragg grating with appropriately generated zone chirp. The presented method can be used for measuring two physical quantities, namely strain and temperature. By providing the same temperature sensitivity and different sensitivity to strain of two parts of a sensor, and experimental measurement of qualities of the proposed system and its calibration (experimental determination of sensitivity), verification of the results obtained from laboratory tests and the possibility of its practical implementation has been confirmed. The sensor grating was placed in such a way that its half was in the zone of a variable value of axial strain caused by changes of the cross-section of the sample. The other half, however, was in the zone of a constant cross-section of the sample and of constant value of strain, caused by the force stretching the sample. The obtained errors of non-linearity of processing characteristics for measuring strain and temperature of the proposed system were 2.7% and 1.5% respectively, while coefficients of sensitivity to strain and temperature were 0.77 x 10-6 m/e and 4.13 x 10-12 m/K respectively. The maximum differences between the values obtained from the indirect measurement and the set values were 110 žε for strain and 3.8°C for temperature, for a strain of 2500 žε and a temperature of 40°C.

7

Niepewność wyznaczenia parametrów siatki Bragga na podstawie jej charakterystyk spektralnych

Wójcik W., Kisała P., Wilkołazka M., Mantyka G.

Pomiary, Automatyka, Komputery w Gospodarce i Ochronie Środowiska

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2009

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nr 4

11-13

PL

W artykule przedstawiono analizę niepewności wyznaczenia niektórych parametrów siatki bragga (ang.: fibre Bragg greting) na podstawie jej widma. Analizowane parametry to wartości okresów siatki w kilku punktach, rozłożonych równomiernie na jej długości. Na podstawie wartości okresów siatki bragga wyznaczone zostały wartości jej wydłużenia względnego. Do obliczeń zastosowano analizę odwrotną. Zdefiniowano zadanie wprost, a przy wykorzystaniu modelu siatki i iteracyjnego algorytmu symulowanego wyżarzania zaprezentowano rozwiązanie zadania odwrotnego, polegającego na wyznaczeniu rozkładu wydłużenia względnego siatki na podstawie jej charakterystyk spektralnych.

EN

In the article analysis of uncertainness of some fiber Bragg grating parameters recovery on the basis of its spectra was presented. Grating periods in many points along this grating were the recovered parameters. On the basis of fibre grating periods values relative strain values was estimated. For calculations the inverse analysis was used. Forward problem was defined and the solution of the inverse problem using grating model and simulated annealing algorithm was presented.

8

The application of inverse analysis in strain distribution recovery using the fibre Bragg grating sensors

Wójcik W., Kisała P.

Metrology and Measurement Systems

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2009

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Vol. 16, nr 4

649-660

EN

This paper outlines the use of inverse analysis in strain distribution recovery. To carry it out we used a sensor with FBG (fibre Bragg grating) and the inverse problem solution was discussed. The study and validation of a mathematical model with the fibre Bragg grating is also outlined in this paper. Computer simulations were carried out using numerical algorithms which performed calculations according to the mathematical structure of the model and respected all remaining values of the FBG sensor elements. Experimental measurements were also conducted using a built measurement system.