The work presents a research into adequacy of two models of an individual fiber optic sensor of a system of identical sensors, which is designed for measuring the railgun rail deflections. The presented models are compared with the data of an experiment. It has been found that a more simple model (in view of the scope of calculation) is more convenient as it concerns the calibration on the grounds of the data of the experiment.
Modelling and experimental investigation of U-h characteristics of fiber-optic reflective displacement transducer, with the aim to obtain the maximal sensitivity and high speed in the displacement and vibration measurements, are presented. Excellent agreement between theory and experiment was obtained, therefore the limiting sensitivity of transducers can be predicted by modelling. Configurations of non-contact fiber optical transducers of the maximal possible sensitivity and speed were found, the metrological parameters which do not depend either on the degradation of the light source intensity or on elements used in the measurements, as well as on the value of the mirror reflection coefficient and changes due to aging. All that increases the reliability of measurement system, which is of utmost importance for process monitoring.
The article presents the results of Matlab simulations and experimental studies of non-contact influence of ultrasonic wave on laser beam. A role of the air-gap and the influence of the air-gap on laser-ultrasonic transmission in optical fiber were examined. Two optical fibers were used with air-gap between them. One fiber was attached to a laser diode and positioned to pass through a hole in a sandwich type transducer and in a velocity transformer. In the velocity transformer (at its end), after leaving small air-gap, to the end of the transformer, the other optical fiber is attached. The second fiber can interact with a given biological structure.
Glass optical fibres are a promising medium for simultaneous laser-ultrasonic applications. The proposed application system is based on simultaneous transmission of laser radiation and ultrasounds in a flexible silica glass fibre. The optical fibre's core was made of SiO_2 (97%) and GeO_2 (3%) and the cladding was 100% SiO_2. The material the optical fibre is made of enables simultaneous transmission of laser radiation and ultrasonic wave. Experiments were performed using a Mach-Zehnder optical waveguide interferometer with single-mode optical fibre coupler. This paper presents measurement results for delivering ultrasonic waves to the optical fibre using longitudinal vibrations generated by a sandwich ultrasonic transducer with a velocity transformer. The study presents the relations concerning simultaneous operation of both types of waves and the possibilities of transmission of low frequency, high power ultrasonic wave in optical fibres using a sandwich type transducer.
Photonic liquid crystal fibers with polymers constitute a new solution based on liquid crystals and microstructured polymer optical fibers opening up new areas in innovative sensing and photonic devices applications. Compared with their silica-based microstructured fibers, it is easier to fabricate exotic microstructured polymer optical fibers by extrusion or drilling at low temperature; their nonlinearity is potentially stronger, the range of available polymers that may be drawn is more diverse and the biocompatibility of polymers is often better. Liquid crystals due to their attractive properties i.e., the high birefringence, high electro-optic and thermo-optic effects are a very good candidate for microstructured polymer optical fiber infiltration to obtain tunable all-in-fiber innovative photonic devices. The paper will discuss basic properties and possible applications of the polymer photonic liquid crystal fibers that will arise from their high optical tunability with external and internal factors. Current research effort is directed towards two main solutions: photonic crystal fibers and microstructured polymer optical fiber-based structures, both infiltrated with liquid crystals of tailored optical properties.
In the paper the luminescence optical fiber used as a temperature sensor is presented. The new construction of rhodamine B doped, polymethyl methacrylate optical fibre with silver coating is shown. The fabrication process and luminescent properties of rhodamine B in sensing fibre are investigated. The attenuation and spectral shift of luminescence peak vs. the fibre length were measured and used for optimization of sensor construction. The characteristics of sensor for temperature range from 293 up to 343 K are shown. The relative sensitivity equal to -5.4× 10^{-4} K^{-1} was obtained. The article presents also the potential applications of presented sensor.
Nonlinear optics of chiral liquid-crystalline media have been in scope of our interest for several years. Our previous observations in the subject had already been reported. This paper discusses a possibility of utilising the nonlinear optical properties of liquid crystals for practical purposes. We discuss an idea of "in line" intensity measurements of laser beam. The idea is based on two optical phenomena which are observed in liquid-crystalline media possessing a periodically stratified structure: nonlinear optical effect and selective light reflection. The effects start to appear by activating light intensities of the order of MW/m^{2}, so the method can be potentially applied at present to high-intensity light beams (corresponding laser power is approximately 0.1 W), although there are now also prospects to lower this value significantly.
In this paper we present our theoretical approach for the description of the light guidance in photonic liquid crystal fibers. In particular, we focus on the numerical methods allowing for a full implementation of the liquid crystals properties (i.e., including their optical anisotropy and molecular orientation), with a final target in characterizing photonic liquid crystal fibers with accessible computational effort. For this purpose suitable analytical formulae required for a full-vectorial description of the optical modes in photonic liquid crystal fibers have been derived. In addition, computational schemes allowing for numerical implementation of theoretical formulations (with the use of the finite-difference scheme) have been developed, validated and optimized. Their numerical convergence has been checked for different structures, as well as for different input parameters (e.g., grid-size). Obtained results have been compared to those analytically calculated, known from literature and/or got with use of commercial software. Moreover, the implemented schemes have been examined in accordance with experimental tests performed on the photonic liquid crystal fiber of interest.
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