A simple fiber sensor to measure angular displacement with high resolution, which is based on whispering gallery mode （WGM） resonance in bent optical fibers,is proposed. The sensor is composed of a single loop forme...A simple fiber sensor to measure angular displacement with high resolution, which is based on whispering gallery mode （WGM） resonance in bent optical fibers,is proposed. The sensor is composed of a single loop formed by loosely tying a knot using single mode fiber. To measure the transmission spectra, a tunable laser and an optic power meter are connected to the two ends of fi- ber loop, respectively. Significant WGM resonances occur over the investigated wavelength range for all the sensors with different bend radius. The angular-displacement sensitivity is studied in the range from -0. 1°to 0. 1°. The detection limit of 1.49 × 10 ^-7 rad can be achieved for the detecting system with the resolution of lpm. The simple loop-structure fiber sensor has potential application prospect in the field of architecture or bridge building with low detection limit and low cost.展开更多
In this paper, a fiber optic displacement sensor with a new reflectivity compensation method is presented. The proposed compensation method is based on two light receiving channels with characteristic displacement sen...In this paper, a fiber optic displacement sensor with a new reflectivity compensation method is presented. The proposed compensation method is based on two light receiving channels with characteristic displacement sensitivities. The sensitivity characteristic for each channel is achieved by using fibers with different numerical apertures. The ratio of the intensity values of the two receiving channels is a function of the object displacement and fairly independent from the reflectivity of the measured object. The sensor is characterized by a well-defined measurement spot. By use of a focus lens mounted onto the fiber optics probe head, the object displacement range can be extended. The sensor is suitable for measurements with changing object reflectivity and demanding distance ranges.展开更多
A low fineness fiber optic Fabry-Perot interferometric displacement sensor has been developed and tested.A 0.005 nm displacement resolution is obtained by using He-Ne laser with a high performance ,photodetectors with...A low fineness fiber optic Fabry-Perot interferometric displacement sensor has been developed and tested.A 0.005 nm displacement resolution is obtained by using He-Ne laser with a high performance ,photodetectors with low noise ,low drift operational amplifiers,6-pole Butterworth filters and perfect digital signal processing circuits.展开更多
A novel system configuration of fiber optic sensor based on optical abso rption is proposed. Several compensation measures are discussed. A simulated exp eriment is designed and the output curve of system is given. Th...A novel system configuration of fiber optic sensor based on optical abso rption is proposed. Several compensation measures are discussed. A simulated exp eriment is designed and the output curve of system is given. The experiment al result shows that these compensation measures are effective on dynamic distu rbances which are caused by background light and optical fiber bend. In addition , the drifts in the light source intensity, fiber losses, and photodetector effi ciency are also compensated.展开更多
Being directed against two kinds of noise in optical fiber sensors,a simple and effective method of automatic compensation for optical fiber sensors is presented.Not only the unstability effect of light source,but als...Being directed against two kinds of noise in optical fiber sensors,a simple and effective method of automatic compensation for optical fiber sensors is presented.Not only the unstability effect of light source,but also zero drift of photoelectronic devices,can be eliminated or enormously restrained with the aid of this method.In another way,by using single-chip microcomputer,the optical fiber sensor system fabricated is connected to a computer network to realize an automatic compensation.展开更多
Railway turnout contact monitoring is very important in high-speed rail operation systems. In order to measure the distance between the sharp rail and the basic rail in a switch system, a wide-range, high-precision fi...Railway turnout contact monitoring is very important in high-speed rail operation systems. In order to measure the distance between the sharp rail and the basic rail in a switch system, a wide-range, high-precision fiber Bragg grating(FBG) displacement sensor was designed. Because the distance between the sharp and basic rails is always greater than 14 cm, the measurement range width and accuracy of the proposed sensor system are ensured through the use of a long spring and a beam of constant strength. A differential compensation method is used to eliminate temperature effects. Test results show that the resolution of the proposed sensor is 0.040 mm and the measuring range is 0—170 mm. A field test was also carried out to evaluate the performance of the sensors.展开更多
We propose a compensation technique based on pulse reference for intensity-modulated optical fiber sensors that can compensate the power fluctuation of the light source, the change of optical components transmission l...We propose a compensation technique based on pulse reference for intensity-modulated optical fiber sensors that can compensate the power fluctuation of the light source, the change of optical components transmission loss, and the coupler splitting ratio. The theoretical principle of this compensation technique is analyzed and a temperature sensor based on fiber coating-covered optical microfiber is carried out to demonstrate the compensation effect. The system noise is measured to be 0.0005 dB with the temperature sensitivity reaching -0.063 dB/℃, and the output drift is 0.006 dB in 2 h at room temperature. The output shows a slight variation （0.0061 dB） when the light source and the common liKht path suffer a 3 dB attenuation fluctuation.展开更多
A novel fiber optics micredisplacement sensor employing a GRIN rod lens is described. The paper presents the operational principle of this device using a geometric optic approach. According to the theoretical analysis...A novel fiber optics micredisplacement sensor employing a GRIN rod lens is described. The paper presents the operational principle of this device using a geometric optic approach. According to the theoretical analysis, we know how to select the parameters of the GRIN rod lens,fibers and other elements in design. DUe to the novel structure, the displacement sensitivity of this sensor is better than the conventional lateral microdisplacment sensor, by a factor of 2.展开更多
We modify the pulse-reference-based compensation technique and propose a low-noise and highly stable optical fiber temperature sensor based on a zinc telluride film-coated fiber tip. The system noise is measured to be...We modify the pulse-reference-based compensation technique and propose a low-noise and highly stable optical fiber temperature sensor based on a zinc telluride film-coated fiber tip. The system noise is measured to be 0.0005 dB, which makes it possible for the detection of the minor reflectivity change of the film at different temperatures. The temperature sensitivity is 0.0034 d B/℃, so the resolution can achieve 0.2℃. The maximum difference of the temperature output values of the sensor at 20℃ at different points in time is 0.39℃. The low cost, ultra-small size, high stability, and good repeatability of the sensor make it a promising temperature sensing device for practical application.展开更多
Time division multiplexing(TDM)architecture is an important approach to creating sensor arrays for massive scale monitoring.But it is paradoxical for the TDM interferometric sensor array to keep a short delay fiber fo...Time division multiplexing(TDM)architecture is an important approach to creating sensor arrays for massive scale monitoring.But it is paradoxical for the TDM interferometric sensor array to keep a short delay fiber for high sensing resolution and meanwhile use low sampling rate for practical applications.In this paper,a phase matching sampling(PMS)paradigm is proposed to address the above contradiction.By matching the phase of the sampling clock with the delay fiber length,combining with multiple-pulses sampling strategy,the proposed PMS method can avoid collecting the redundant information,facilitating the decreasing of sampling rate as well as delay fiber length of the TDM sensing system.The proof-of-concept experiments on an 8-channel TDM interferometric system demonstrate that when the sampling rate is fixed at 20 MS/s,by applying the PMS algorithm,the delay fiber length can be shortened from 100 m to 1 m,compared with applying the conventional sampling method.It reduced the phase noise of the system by a factor of 10 at 1 mHz and by a factor of 50 at 1 Hz.The PMS algorithm for greatly reducing the sampling rate is expected to fuel the TDM interferometric sensor arrays for many applications.展开更多
Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study pr...Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study presents a state-of-the-art review of the DFOS applications for monitoring and assessing the deformation behavior of typical tunnel infrastructure,including bored tunnels,conventional tunnels,as well as immersed and cut-and-cover tunnels.DFOS systems based on Brillouin and Rayleigh scattering principles are both considered.When implementing DFOS monitoring,the fiber optic cable can be primarily installed along transverse and longitudinal directions to(1)measure distributed strains by continuously adhering the fiber to the structure’s surface or embedding it in the lining,or(2)measure point displacements by spot-anchoring it on the lining surface.There are four critical aspects of DFOS monitoring,including proper selection of the sensing fiber,selection of the measuring principle for the specific application,design of an effective sensor layout,and establishment of robust field sensor instrumentation.These four issues are comprehensively discussed,and practical suggestions are provided for the implementation of DFOS in tunnel infrastructure monitoring.展开更多
Different from the traditional contact surface topography measurement,reflective intensity-modulated fiber optic sensor(RIM-FOS)has the unique advantages of non-contact nondestructive detection.This paper briefly intr...Different from the traditional contact surface topography measurement,reflective intensity-modulated fiber optic sensor(RIM-FOS)has the unique advantages of non-contact nondestructive detection.This paper briefly introduces the principle and performance of RIM-FOS for surface topography measurement and compares with several other methods of topography measurement.Based on the review of its development process,this paper summarizes and analyses the hot issues of RIM-FOS in the surface topography measurement,then predicts the future trend for a guidance of the further study.展开更多
A multiplexed white light interferometric fiber optic twin-sensor-array was designed to monitor the structural health of large buildings.In this sensing system,based on a Michelson interferometer,an optical path match...A multiplexed white light interferometric fiber optic twin-sensor-array was designed to monitor the structural health of large buildings.In this sensing system,based on a Michelson interferometer,an optical path matching technique is used to demodulate each twin-sensor.Each twin-sensor-array consists of a 2×N sensing element linked by a 3 dB coupler.When one of the twin-sensor is used to measure strain,variations caused by temperature can be compensated for by referencing the other twin-sensor.The multiplexing capacity of the sensing scheme has been analyzed and experimental results with a 2×3 twin-sensor-array are given.展开更多
A magneto-optical sensor, using a dual quadrature polarimetfic processing scheme, was evaluated for current metering and protection applications in high voltage lines. Sensor calibration and resolution were obtained i...A magneto-optical sensor, using a dual quadrature polarimetfic processing scheme, was evaluated for current metering and protection applications in high voltage lines. Sensor calibration and resolution were obtained in different operational conditions using illumination in the 1550-nm band. Results obtained indicated the feasibility of interrogating such sensor via the optical ground wire （OPGW） link installed in standard high power grids. The polarimetric bulk optical current sensor also was theoretically studied, and the effects of different sources of error considering practical deployment were evaluated. In particular, the interference from external magnetic fields in a tree-phase system was analyzed.展开更多
A new optical intensity-based sensing mechanism for the measurement of refractive index and minute displacement is proposed in this paper, which is based on modifying the amount of light coupled between two parallel l...A new optical intensity-based sensing mechanism for the measurement of refractive index and minute displacement is proposed in this paper, which is based on modifying the amount of light coupled between two parallel long-period fiber gratings. The characteristics of this sensing mechanism with experiments and simulation results are demonstrated.展开更多
基金Supported by the National Basic Research Program of China （ ＂973＂ Program） （ 2011 CB013000 ） the National Natural Sci- ence Foundation of China （NSFC） （ 90923039 51105038）
文摘A simple fiber sensor to measure angular displacement with high resolution, which is based on whispering gallery mode （WGM） resonance in bent optical fibers,is proposed. The sensor is composed of a single loop formed by loosely tying a knot using single mode fiber. To measure the transmission spectra, a tunable laser and an optic power meter are connected to the two ends of fi- ber loop, respectively. Significant WGM resonances occur over the investigated wavelength range for all the sensors with different bend radius. The angular-displacement sensitivity is studied in the range from -0. 1°to 0. 1°. The detection limit of 1.49 × 10 ^-7 rad can be achieved for the detecting system with the resolution of lpm. The simple loop-structure fiber sensor has potential application prospect in the field of architecture or bridge building with low detection limit and low cost.
文摘In this paper, a fiber optic displacement sensor with a new reflectivity compensation method is presented. The proposed compensation method is based on two light receiving channels with characteristic displacement sensitivities. The sensitivity characteristic for each channel is achieved by using fibers with different numerical apertures. The ratio of the intensity values of the two receiving channels is a function of the object displacement and fairly independent from the reflectivity of the measured object. The sensor is characterized by a well-defined measurement spot. By use of a focus lens mounted onto the fiber optics probe head, the object displacement range can be extended. The sensor is suitable for measurements with changing object reflectivity and demanding distance ranges.
文摘A low fineness fiber optic Fabry-Perot interferometric displacement sensor has been developed and tested.A 0.005 nm displacement resolution is obtained by using He-Ne laser with a high performance ,photodetectors with low noise ,low drift operational amplifiers,6-pole Butterworth filters and perfect digital signal processing circuits.
文摘A novel system configuration of fiber optic sensor based on optical abso rption is proposed. Several compensation measures are discussed. A simulated exp eriment is designed and the output curve of system is given. The experiment al result shows that these compensation measures are effective on dynamic distu rbances which are caused by background light and optical fiber bend. In addition , the drifts in the light source intensity, fiber losses, and photodetector effi ciency are also compensated.
文摘Being directed against two kinds of noise in optical fiber sensors,a simple and effective method of automatic compensation for optical fiber sensors is presented.Not only the unstability effect of light source,but also zero drift of photoelectronic devices,can be eliminated or enormously restrained with the aid of this method.In another way,by using single-chip microcomputer,the optical fiber sensor system fabricated is connected to a computer network to realize an automatic compensation.
基金supported by the National Natural Science Foundation of China(Nos.51578349 and 51608336)the China Postdoctoral Science Foundation(No.2017M610170)
文摘Railway turnout contact monitoring is very important in high-speed rail operation systems. In order to measure the distance between the sharp rail and the basic rail in a switch system, a wide-range, high-precision fiber Bragg grating(FBG) displacement sensor was designed. Because the distance between the sharp and basic rails is always greater than 14 cm, the measurement range width and accuracy of the proposed sensor system are ensured through the use of a long spring and a beam of constant strength. A differential compensation method is used to eliminate temperature effects. Test results show that the resolution of the proposed sensor is 0.040 mm and the measuring range is 0—170 mm. A field test was also carried out to evaluate the performance of the sensors.
基金supported by the National Natural Science Foundation of China(Nos.61505258 and 11574397)the Scientific Research Project of the National University of Defense Technology(No.JC15-11-02)
文摘We propose a compensation technique based on pulse reference for intensity-modulated optical fiber sensors that can compensate the power fluctuation of the light source, the change of optical components transmission loss, and the coupler splitting ratio. The theoretical principle of this compensation technique is analyzed and a temperature sensor based on fiber coating-covered optical microfiber is carried out to demonstrate the compensation effect. The system noise is measured to be 0.0005 dB with the temperature sensitivity reaching -0.063 dB/℃, and the output drift is 0.006 dB in 2 h at room temperature. The output shows a slight variation （0.0061 dB） when the light source and the common liKht path suffer a 3 dB attenuation fluctuation.
文摘A novel fiber optics micredisplacement sensor employing a GRIN rod lens is described. The paper presents the operational principle of this device using a geometric optic approach. According to the theoretical analysis, we know how to select the parameters of the GRIN rod lens,fibers and other elements in design. DUe to the novel structure, the displacement sensitivity of this sensor is better than the conventional lateral microdisplacment sensor, by a factor of 2.
基金supported by the National Natural Science Foundation of China(Nos.11574397,61775238,61705262,and 61705263)the Scientific Research Project of National University of Defense Technology(No.JC15-11-02)
文摘We modify the pulse-reference-based compensation technique and propose a low-noise and highly stable optical fiber temperature sensor based on a zinc telluride film-coated fiber tip. The system noise is measured to be 0.0005 dB, which makes it possible for the detection of the minor reflectivity change of the film at different temperatures. The temperature sensitivity is 0.0034 d B/℃, so the resolution can achieve 0.2℃. The maximum difference of the temperature output values of the sensor at 20℃ at different points in time is 0.39℃. The low cost, ultra-small size, high stability, and good repeatability of the sensor make it a promising temperature sensing device for practical application.
基金financial supports from Ministry of Science and Technology of the People’s Republic of China under Grant(No.2022YFC2203904)in part by Open Projects Foundation under Grant of State Key Laboratory of Optical Fiber and Cable Manufacture Technology(YOFC)(No.SKLD2306).
文摘Time division multiplexing(TDM)architecture is an important approach to creating sensor arrays for massive scale monitoring.But it is paradoxical for the TDM interferometric sensor array to keep a short delay fiber for high sensing resolution and meanwhile use low sampling rate for practical applications.In this paper,a phase matching sampling(PMS)paradigm is proposed to address the above contradiction.By matching the phase of the sampling clock with the delay fiber length,combining with multiple-pulses sampling strategy,the proposed PMS method can avoid collecting the redundant information,facilitating the decreasing of sampling rate as well as delay fiber length of the TDM sensing system.The proof-of-concept experiments on an 8-channel TDM interferometric system demonstrate that when the sampling rate is fixed at 20 MS/s,by applying the PMS algorithm,the delay fiber length can be shortened from 100 m to 1 m,compared with applying the conventional sampling method.It reduced the phase noise of the system by a factor of 10 at 1 mHz and by a factor of 50 at 1 Hz.The PMS algorithm for greatly reducing the sampling rate is expected to fuel the TDM interferometric sensor arrays for many applications.
基金funding support from Rijkswaterstaat,the Netherlands,and European Union’s Horizon 2020 Research and Innovation Programme(Project SAFE-10-T under Grant No.723254)China Scholarship Council,and National Natural Science Foundation of China(Grant No.42225702).
文摘Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study presents a state-of-the-art review of the DFOS applications for monitoring and assessing the deformation behavior of typical tunnel infrastructure,including bored tunnels,conventional tunnels,as well as immersed and cut-and-cover tunnels.DFOS systems based on Brillouin and Rayleigh scattering principles are both considered.When implementing DFOS monitoring,the fiber optic cable can be primarily installed along transverse and longitudinal directions to(1)measure distributed strains by continuously adhering the fiber to the structure’s surface or embedding it in the lining,or(2)measure point displacements by spot-anchoring it on the lining surface.There are four critical aspects of DFOS monitoring,including proper selection of the sensing fiber,selection of the measuring principle for the specific application,design of an effective sensor layout,and establishment of robust field sensor instrumentation.These four issues are comprehensively discussed,and practical suggestions are provided for the implementation of DFOS in tunnel infrastructure monitoring.
基金Youth Science and Technology Research Foundation of Shanxi Province(No.2015021104)Programs for Science and Technology Development of Shanxi Province(No.201703D121028-2)
文摘Different from the traditional contact surface topography measurement,reflective intensity-modulated fiber optic sensor(RIM-FOS)has the unique advantages of non-contact nondestructive detection.This paper briefly introduces the principle and performance of RIM-FOS for surface topography measurement and compares with several other methods of topography measurement.Based on the review of its development process,this paper summarizes and analyses the hot issues of RIM-FOS in the surface topography measurement,then predicts the future trend for a guidance of the further study.
基金National Natural Science Foundation of China(60577005)Specialized Research Fund for the Doctoral Program of Higher Education Institute of MOE,China,to Harbin Engineering University
文摘A multiplexed white light interferometric fiber optic twin-sensor-array was designed to monitor the structural health of large buildings.In this sensing system,based on a Michelson interferometer,an optical path matching technique is used to demodulate each twin-sensor.Each twin-sensor-array consists of a 2×N sensing element linked by a 3 dB coupler.When one of the twin-sensor is used to measure strain,variations caused by temperature can be compensated for by referencing the other twin-sensor.The multiplexing capacity of the sensing scheme has been analyzed and experimental results with a 2×3 twin-sensor-array are given.
文摘A magneto-optical sensor, using a dual quadrature polarimetfic processing scheme, was evaluated for current metering and protection applications in high voltage lines. Sensor calibration and resolution were obtained in different operational conditions using illumination in the 1550-nm band. Results obtained indicated the feasibility of interrogating such sensor via the optical ground wire （OPGW） link installed in standard high power grids. The polarimetric bulk optical current sensor also was theoretically studied, and the effects of different sources of error considering practical deployment were evaluated. In particular, the interference from external magnetic fields in a tree-phase system was analyzed.
文摘A new optical intensity-based sensing mechanism for the measurement of refractive index and minute displacement is proposed in this paper, which is based on modifying the amount of light coupled between two parallel long-period fiber gratings. The characteristics of this sensing mechanism with experiments and simulation results are demonstrated.
