Papers by Keyword: Fiber Optic Sensor

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Authors: İsmet Gücüyener, Erdal Emel
Abstract: Vibration measurement of CNC milling is one of the used techniques for prediction of tool wear. Monitoring of tool wear is very important since a worn tool will affect machine and workpiece either. We developed a fiber-optic sensor for spindle vibration of CNC face-milling machine. The sensor is based on monitoring loss of light from the fiber core. For this sensor a laser light transmitter circuit, a sense plane construction, and a light receiver circuit are designed. Designed fiber-optic sensor is tested on Taksan TMC 650V face-milling machine. Obtained signals from this sensor is investigated in time domain and frequency domain and showed that it is valuable to tool ware monitoring.
Authors: Qing Guo Shi, Lu Na Ying, Lu Wang, Bao Jin Peng, Chao Fu Ying
Abstract: For marine water pollution problems, According to the phenomenon that the refractive index of the seawater will change after been polluted .we designed a new fiber optical sensor, and completed a marine pollution monitoring automatic warning system with the sensor. One S (single mode)-M (multimode)-S-M-S structural optical fiber sensor based on the theory of M-Z Interference was made. Due to de refractive index of the fiber cladding will be affected by the environmental solution. We can determine the relationship between the movement of interference spectrum and the refractive index of the solution. With a center wavelength of 1553nm fiber Bragg grating and a coupler to obtain the change of the intensity of the light, then though the specific circuit, we can change the light intensity into the voltage values. Then enter the computer through the acquisition card, real-time reporting of environmental refractive index size, and according to the software set threshold alarms. The refractive index in the range of 1.330-1.390, the system of measurement error is less than 1%.
Authors: Shi Wei Zhang, Wen Sheng Liang, Guo Zhao Ji
Abstract: Considering the difficulty to precisely indicate the specified height for transparent or semitransparent thin liquid column, a novel fiber-optic liquid level sensor is reported which remarkably enhances the sensitivity by regulating the external light path based on the principle of light refraction. The structure and working principle of this sensor is introduced. A light path model is developed on the condition that the incident light ray obliquely penetrates the medium in the liquid level indicator. The formulae of deflection angle are deduced. Factors affecting the precision of the sensor are analyzed by means of an example. Finally the feasibility of this novel design is verified by experiments.
Authors: Lin Yang, Andreas Frank, Robert Wüest, Berkan Gülenaltin, Miklos Lenner, Georg M. Müller, Klaus Bohnert
Abstract: We consider an interferometric fiber optic current sensor with a fiber coil operated in reflection and compare three different techniques to prepare the coil: thermally annealed coils, stress-free packaging of a bare low birefringent fiber in a fused silica capillary, and coils from highly birefringent spun fiber. In particular we theoretically and experimentally investigate how the fiber retarder that generates the near left and right circular light waves in the sensing fiber must be prepared for temperature compensation of the Faraday effect in the three cases. All three methods can achieve accuracy within ±<0.2% over an extended temperature range but they considerably differ in their practical challenges.
Authors: Dai Xie Chen, Bo Hua Yin, Yu Ju, Yun Sheng Lin, Ming Zhang Chu, Han Li
Abstract: As AFM tip approach speed is one of the key factors for AFM industrial on-line detection application, a sectional fast tip approach method composed of rough approach and mild approach processes is introduced here. In rough approach process, AFM tip can be approached by step motor to certain distance upon the sample surface with high speed, as a homemade dual-channel reflective intensity modulated fiber optic displacement sensor (DC-RIMFODS) can be integrated to AFM scan head easily to detect the stop position. While continued with mild approach process after rough approach, step motor can run slowly with a common PI feedback controller for Z scanner to make the tip get in touch with sample surface softly. Experimental results show that with the well-defined fiber optical sensor positioning accuracy and repeatability, the tip-sample distance can be limited in certain range after rough approach with 1mm/s high speed, and the whole AFM tip approach process can be finished in 20s by continuing with mild approach, while the initial tip-sample distance is about 10mm.
Authors: Leszek R. Jaroszewicz, Zbigniew Krajewski, Jerzy K. Kowalski, Anna Kurzych, Zbigniew Raszewski
Abstract: We outline the development and application of the Autonomous Fibre-Optic Rotational Seismograph (AFORS), which utilizes the Sagnac effect for a direct measurement of seismic rotation. The main advantage of AFORS is it complete insensitivity to linear motions as well as a direct measurement of rotational components emitted during seismic events. The presented system contains a special autonomous signal processing unit which optimizes its operation for the measurement of rotation motions, whereas applied telemetric system based on the Internet allows for a remote AFORS control. The laboratory investigation of the two such devices indicated they keep accuracy no less than 5.1·10-9 to 5.5·10-8 rad/s in the frequency bandpass from 0.83 Hz to 106.15 Hz with protect linear changes of sensitivity in above bandpass. The experimental results of AFORS-1 application for continuous monitoring the rotational events in the Książ (Poland) seismological observatory are also presented.
Authors: Dalibor Ciprian, Petr Hlubina
Abstract: Theoretical analysis of surface plasmon resonance ber optic sensor based on a core-shell nanoparticle layer is presented. The sensing structure consists of a standard step-indexmultimode optical ber whose bare fused silica core is coated by Ag core-shell nanoparticlemonolayer. Its optical constants were obtained using e ective media (Maxwell-Garnett) theory.Theoretical model based on thin- lm optics approach is used to compute the normalized powertransfer through the sensing part of the ber in spectral domain. The computed results areused to obtain the sensitivity and detection accuracy of the sensing scheme with respect tothe concentration of analyte components. The inuence of nanoparticle geometry on the sensorperformance is discussed.
Authors: Daniele Zonta, Matteo Pozzi, Hua Yong Wu, Daniele Inaudi
Abstract: This paper presents the laboratory validation of a prototype optic-fiber instrumented structural element. The element is a reduced-scale reinforced concrete beam, of dimensions 3.8×0.3×0.5m that can be pre-stressed by an internal Dywidag bar. The sensing technology is based on a multiplexed version of the SOFO strain sensor, prepared in the form of a 3-field smart composite bar; in-line multiplexing is obtained by separating each measurement field through broadband FBGs. The experiment aims to identify the response of the sensors to differing damage conditions artificially produced in the element, including cracking and loss of prestressing. A numerical algo-rithm, based on Bayesian logic, is applied to real-time diagnosis: by processing the sensor meas-urements and prior information, the method assigns a posterior probability to each assumed damage scenario, as well as the updated probability distributions for each relevant structural parameter. With respect to classical damage detection approaches, the merit of those based on Bayesian logic is to provide not only information on the damage, but also the degree of confidence in this informa-tion. The paper discusses the ability of the system to identify the differing damage conditions. The reported test clearly shows that an occurrence such as a loss of prestressing can be recognized early with a high degree of reliability based on the strain data acquired.
Authors: Daniele Tosi, Massimo Olivero, Guido Perrone
Abstract: In the present work we report on the development of a low cost interrogation system of fiber Bragg grating sensors for structural health monitoring. The developed scheme uses two gratings and a directional coupler as sensing point, and it includes self-compensation of temperature effects. The reading equipment consists of a standard photodiode for telecom applications with custom signal-conditioning electronics. The characterization of multiplexed sensors, carried out in real framework conditions, shows that the system can work in a temperature range of -20÷+40°C, making strain measurements up to at least 320με with an accuracy of ~3% and an acquisition rate of 12 samples/min. Further, a budget evaluation is drawn to asses the feasibility of our interrogation system as a low cost solution to increase the extent of structural health monitoring in funds-limited applications.
Authors: Sergey A. Babin, Alexey G. Kuznetsov, Ivan S. Shelemba
Abstract: Two types of distributed fiber sensor systems for temperature measurements have been developed: the first one is multi-point Fiber Bragg Grating based system with interrogation by CW tunable laser and nonlinearity compensation by reference interferometer. The second device is Raman scattering system based on optical time domain reflectometry (OTDR) with a pulsed laser providing spatial resolution of several meters and efficient spectral filtering of the Stokes and anti-Sokes signals by means of WDM couplers. Physical effects important for the systems operation are analyzed and their parameters are compared and optimized for applications in oil-gas industry and turbogenerator temperature monitoring.
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