Papers by Keyword: Fiber Optic

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Authors: Ning Yang, Qi Qiu, Jun Su
Abstract: In this paper, we report a dual-wavelength temperature sensor based on fiber optic delay. This temperature sensor don’t need to rely on accurate spectrum measurement, but to realize temperature measurement by detecting the variation of delay, which can efficiently reduce the cost and complexity of sensor system. In this dual-wavelength system, one wavelength of light is used as a reference and the other one is used for temperature sensing, so this design can effectively eliminate the negative influences of unstable external environment. The principle of this temperature sensor is theoretically derived, the schematic of sensor system is analyzed and the feasibility of this method is tested in the temperature range of 0°C-80°C. Results indicate that, this temperature sensor is able to achieve temperature measurement in a simple way with low cost.
Authors: G.J. Hwang, W.H. Ko
Abstract: A multi-fiber reflection displacement micrometer is developed. The device consists of a light source and a receiving fiber-array of identical fibers and photo detectors that detect the light reflected from the surface being measured. The differential output of each neighboring fiber pair is proportional to the surface displacement in a section of the total range. The light intensity variation of the source and the reflectance change of the surface are compensated when the differential output is divided by the summation output. A scale voltage is given to each output of neighboring fibers in order to shift each output to correspond to the actual displacement within the total range, which can be varied by selecting the number of fibers in the receiving fiber array. The micrometer offers the advantages of wide range, non-contact, no electrical interference, simplicity, and low cost. It can be used in medical experiments and laboratory instruments.
Authors: Zhi Zhong Li, Yuan Zheng, Wei Guo Dai, Yi Chuan Wang
Abstract: A new kind of passive underwater acoustic sensor based on fiber Bragg grating is reported. The pressure sensitivity of the sensor is enhanced three orders of magnitude being packaged with polymer material, which is a foundation for underwater acoustic detection. An intensity modulation scheme is adopted to realize high-accuracy detection due to the extra-narrow line-width laser. The experimental results show that the sensor’s noise-limited pressure detection resolution is about 61dB (0dB=1μPa/ Hz ) at 500 Hz, which satisfies the application of underwater target detection.
Authors: Bojan M. Dakić, Jovan S. Bajić, Dragan Z. Stupar, Miloš P. Slankamenac, Miloš B. Živanov
Abstract: In this paper a novel fiber-optic mass flow sensor based on coriolis force is presented. As sensing elements two fiber-optic curvature sensors mounted on elastic rubber tube are used. Rubber tube with sensing elements is excited by stepper motor. Produced system has the option of varying angle and speed of excitation. The bending of the fibers at the sensitive zone on curvature sensor changes the intensity of light traveling through the optical fiber. Curvature sensors are attached to the rubber tube so that they can measure phase difference produced by coriolis force. Mass flow rate is obtained by digital signal processing technique for phase difference detection.
Authors: Noor A. Ahmed
Abstract: Laser Doppler Velocimetry is an important flow diagnostic methodology used in modern day fluid flow investigations. The present paper describes the design and manufacturing aspects of a novel fibre optic LASER Doppler probe head intended for three dimensional measurements in a complex flow field. The paper particularly concentrates on the tight tolerances required of the various components associated with the probe head to achieve the desired measurement volume. Keywords: Fibre Optic, Laser Doppler, Velocimetry, three-dimensional, complex flow field
Authors: Mark T. Morgan, Gi Young Kim, Daniel Ess, Aparna Kothapalli, Byoung Kwon Hahm, Arun Bhunia
Abstract: Frequent outbreaks of foodborne illness have been increasing the need for simple, rapid and sensitive methods to detect foodborne pathogens. Conventional methods for pathogen detection and identification are labor-intensive and take days to complete. Some immunological rapid assays are developed, but these assays still require prolonged enrichment steps. Biosensors have shown great potential for the rapid detection of foodborne pathogens. Among the biosensors, fiber-optic methods have much potential because they can be very sensitive and simple to operate. Fiber-optic biosensors typically use a light transmittable, tapered fiber to send excitation laser light to the detection surface and receive emitted fluorescent light. The fluorescent light excited by an evanescent wave generated by the laser is quantitatively related to fluorophor-labeled biomolecules immobilized on the fiber surface. A portable and automated fiber-optic biosensor, RAPTOR (Research International, Monroe, WA), was used to detect Salmonella enteritidis in food samples. A binding inhibition assay based on the biosensor was developed to detect the bacteria in hot dog samples. The biosensor and the binding inhibition assay could detect 104 cfu/ml of bacteria in less than 10 min of assay time.
Authors: Gi Young Kim, Mark T. Morgan, Daniel Ess, Byoung Kwon Hahm, Aparna Kothapalli, Angela Valadez, Arun Bhunia
Abstract: Fiber-optic biosensor uses light transmittable tapered fiber to send excitation laser light and receive emitted fluorescent light. The fluorescent light excited by an evanescent wave generated by the laser is quantitatively related to biomolecules immobilized on the fiber surface [1]. An automated fiber-optic biosensor based detection method for Listeria monocytogenes was developed in this research. Detections of Listeria monocytogenes in hotdog sample were performed to evaluate the method. By using the detection method with automated fiber-optic biosensor, 5.4×107 cfu/ml of Listeria monocytogenes was able to detect.
Authors: Na Zhao, Ke Qin Ding
Abstract: The crack is easily generated in the metal structure because of fatigue. It has a strong impact on structural safety. To reduce accident and losses, it is important to detect the local damage such as active crack. The general method to detect the local damage is acoustic-emission technique. But it has the disadvantages of short distance transmission, interfered easily and so on. In this paper, the fiber optic acoustic emission sensor system is designed and developed. A lot of experiments have been done in laboratory. It is shown that the new system has long distance transmission, and has high anti-interference etc. It can meet the demand of local damage detection about the metal structure.
Authors: Chao Wang, Wei Liu, Jin Shen, Bo Xue Tan
Abstract: The fiber optic dynamic light scattering has become an important technique in applied science for analysing the particle size. This paper reviews these fiber optic dynamic light scattering systems. It analyses the theory of measurement and indicates the structural features of every system. Then this paper discusses the development tendency of the fiber optic dynamic light scatterin systems.
Authors: Rafael Amat, H. García-Miquel, D. Barrera, Galina V. Kurlyandskaya, S. Sales
Abstract: We have designed a magneto-optical sensor based on fiber Bragg grating (FBG) and Metglas 2605CO (Fe67Co18B14Si1) material with magnetostriction coefficient of 35ppm. The FBG sensor is glued between two sheets of Metglas. FBG-based detectors are sensitive to both temperature changes (approximately 10pm/°C) and mechanical stress (approx. 1.15pm). Also due to the thermal expansion of Metglas, it becomes imperative to isolate the joint effects of thermal expansion of Metglas and the FBG temperature drifts. This is achieved by introducing an additional FBG used as a temperature sensor. We have characterized the responses of the sensor in two directions simultaneously: parallel and perpendicular to the direction of the applied magnetic field.
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