Papers by Keyword: Fiber Bragg Grating (FBG)

Paper TitlePage

Authors: C.S. Shin, C.Y. Liu, S.C. Hsu
Abstract: During clinical operation in root canals, NiTi endodontic rotary instruments are subjected to alternating tension and compression and are prone to accidental fracture without prior warning. Once broken, extracting the fractured part from the canal is difficult and is annoying to both the patient and the dentist. Warning of an imminent fracture during clinical use will be a great help to avoid medical and legal complications. To this end, a monitoring technique that involves the picking up and analysis of the stress wave signals due to the cutting and rubbing at the canal wall-instrument blade interface was investigated. Both the stress wave conducted through solid and the sound wave conducted in air were monitored. The former was picked up by a Fiber Bragg Grating (FBG) and the latter with a microphone. When cracking developed in a rotary instrument, we expect the natural vibration frequency of the instrument as well as the characteristics of cutting/rubbing with the canal wall change. From the raw signal intensity history, it is possible to differentiate whether the instrument is operating but there is no clue when a fatigue crack has initiated. By employing Fast Fourier Transform (FFT) on the signal, we can reveal the energy associated with different frequencies. With characteristic frequency we refer to the frequency that is associated with the highest signal intensity. It was found that the energy intensity of the characteristic frequency varied in a well-defined pattern during the process of fatigue testing of the rotary instrument. Towards the end of fatigue life, a large intensity spike of the characteristic frequency was observed and this was shown to be associated with the occurrence of a fatigue crack. It is hoped that with this information, the fatigue failure of rotary instruments can be closely monitored to avoid/alleviate the occurrence of unexpected fracture during clinical use.
Authors: Dong Sheng Wang, Yu Tian Wang, Wei Wei Pan
Abstract: Based on the relation between the wavelength shift of sensing FBG and the strain, a flow measuring device of the circular target binding Fiber Bragg Grating with the cantilever is designed and the mathematical model based on a circular target flow measurement system is established. Through the flow experiment, we can get the flow test result. The experimental data error analysis can be concluded to verify the feasibility and precision of the design.
Authors: Ya Ge Zhan, Jun Luo, Hua Wu
Abstract: A composite structure multi-parameter sensor based on an embedded polarization maintaining fiber grating (PMFG) has been studied theoretically and experimentally. A fiber Bragg grating (FBG, for comparison with the PMFG) and a PMFG are embedded in glass fiber reinforced polymer (GFRP) laminates in the experiment. The temperature and stress response characteristics of the fiber gratings embedded in corresponding GFRP are studied. The temperature sensitivity of the FBG improves from 10.64pm/°C to 21.66pm/°C. The temperature sensitivity of the PMFG improves from 10.22m/°C to15.7pm/°C (x-axis) and from 9.56 pm/°C to15.1 pm/°C (y-axis). The peak wavelengths in the reflection spectra of the two gratings all shift linearly with the temperature and/or the stress of GFRP. The two temperature-wavelength sensitivities and the two stress-wavelength sensitivities of the PMFG are all different with each other. The temperature and the stress of the GFRP can be calculated according to the two peak wavelength (in x-axis and in y-axis) shifts of a PMFG. Therefore, one PMFG is component for monitoring the temperature and the stress of a composite structure simultaneously according to the experimental results.
Authors: M.X. Jiao, E.G. Zhao, Y.M. Liu, R.L. Qi
Abstract: A high sensitivity pressure sensing system with a fiber Bragg grating (FBG) using the transverse strain characteristic of a straight bourdon tube (SBT) is presented and demonstrated for the first time to our knowledge. The transverse strain of the SBT makes the FBG tensioned. The pressure can be determined by measuring the shift of the Bragg wavelength. The experimentally obtained results indicate that the shift of the Bragg wavelength changes linearly with the applied pressure and the sensitive coefficients of pressure are approximately 6.22x10-3MPa-1. This represents a sensitivity value approximately 9.66x10-3pm/Pa. The pressure sensing system shows little hysteresis error.
Authors: Chi Chih Lai, I Nan Chang, Hsing Cheng Chang, Chang Chou Hwang, Wen Fung Liu, Chin Hsiang Ma, Ya Hui Chen
Abstract: An optical mechatronic magnetic microsensor with temperature compensation based on fiber Bragg grating (FBG) and microelectromechanical system (MEMS) technologies is demonstrated. Parallel nickel-electroplated cantilever beams are fabricated as an attractive bending mechanism for pushing the optical fiber. Related stress induced cantilever bend caused by magnetic force driving reflective wavelength shift that exactly corresponds with photo-elastic coupling effect to characterize microsensors. Two different cycles of gratings in the same fiber have fabricated to perform the function of magnetic sensing and temperature compensation for reducing temperature-induced bias in magnetic measurement automatically. The sensitivity of 2.238 T/nm with null temperature response has obtained which excited by Nd-Fe-B magnets with residual magnetic strength up to 1.26 Tesla.
Authors: Xin Liu
Abstract: Fiber grating is an optical passive device which is developed very fast in recent years. FBG is the most grating which is used as fiber sensor. Cross-sensitivity of fiber grating sensor is an important problem which is restricted the development of the fiber sensor. We do a deep research on the cross-sensitivity problem of the Fiber Bragg grating in this paper. Based on the basic principle of how the cross-sensitivity problem is produced, we suggest a modification in a dual-wavelength matrix calculation method which is used to solve the cross-sensitivity problem in traditional. The modified dual-wavelength matrix calculation method has a higher accuracy than the traditional method.
Authors: Wei Li, Yong Jia Zhang, Hong Qiao Wen
Abstract: In order to increase the multiplying density of Fiber Bragg Grating (FBG) sensors, a novel FBG Sensing System based on CDMA technology has been developed. Simulation experiment indicates the CDMA technology combine with optical fiber grating sensing system together successfully. Furthermore, the system can distinguishes the FBG and enhance the FBG network band utilization.
Authors: Lei Zhang, De Cun Dong, Jun Ting Lin, Zhi Peng Yuan, Jie Yi Mao
Abstract: The switch machine gap monitoring technology is the main technology to detect the turnout’s service status and ensure the operational safety. This paper deduces a mathematical model of the gap monitoring on the basis of the analysis of the gap monitoring techniques and the working principle of the switch machine. It uses the Fiber Bragg Grating technology to extract and analyze the gap data. The results show that the use of Fiber Bragg Grating could get a more accurate monitoring of the gap, and provide a more reliable support for the switch machine maintenance at the same time.
Authors: Lin Jun Cai, Zheng Ying Li, Zhi Hao Tang, Wei Meng, Quan Liu
Abstract: The FBG sensor technologies used for real-time monitoring of the mechanical vibration have attracted more and more concerns from both academic and industrial domains. In practical applications, the vibration frequency of the equipments generally reach up to a few hundred to several thousand Hz, however, the existing FBG demodulator is incompetent to meet the actual requirements of vibration monitoring in terms of demodulation speed and algorithm structures. To solve this problem while achieving a higher accuracy at a relatively lower computation cost, a novel adaptive semi-peak-seek algorithm based on state machine is proposed, which can be divided into three parts including data collection, data analysis and data verification. The experiment result shows that for the demodulation speed of 2 KHz, we can reach a demodulation accuracy of 1pm and a static noise within ±2pm. On the basis of a long term test, the stability error that less than 2pm and the system dynamic range of 0~ -30db are concluded, and the measurement error with the optical power attenuation is limited to 4pm. Thus, the proposed algorithm is capable to meet the requirements of high-speed demodulation devices in terms of speed, precision, stability and anti-interference properties.
Authors: Fang Fang Liu, Hao Jie Xia, Li Juan Chen, Hong Li Li, Ye Tai Fei
Abstract: The trend towards miniaturisation in manufacturing has led to a requirement for the technique of micro /nano measurements capable of measuring tiny features on small components. This paper presents the development of a new sensing method for micro/nano displacement measurements based on fiber Bragg grating (FBG) sensors. In this machine, some new ideas are integrated into the design, such as the suspended FBG probe stem, the fiber fused microball tip, and the double-FBG probe structure. Test shows the microball tip diameter can be less than 300 um. It has been proved by preliminary experimental results that the measurement resolution can reach 50nm.
Showing 1 to 10 of 153 Paper Titles