Modulation of light scattering by liquid crystal droplets dispersed in a polymer matrix by an electric field forms the basis of a compact electric field sensor. A thin layer of polymer dispersed liquid crystal is interspersed between two cleaved end faces of multimode fiber. In the absence of an electric field the droplets are randomly oriented. The anisotropy of the refractive index of the liquid crystal causes light to be scattered out of the acceptance angle of the receiving fiber. As the major axis of the indicatrix of the droplets aligns with the field, the anisotropy in refractive index is lowered. The fraction of the light which is scattered is therefore reduced. In this paper we report on the properties of an electric field sensor envisaged for application to overhead transmission lines and utility substations. We discuss linearity, hysteresis, and the effect of temperature on the sensor.
{"title":"Multimode optical fiber polymer-dispersed liquid crystal electric field sensor","authors":"B. Lacquet, P. Swart","doi":"10.1117/12.245578","DOIUrl":"https://doi.org/10.1117/12.245578","url":null,"abstract":"Modulation of light scattering by liquid crystal droplets dispersed in a polymer matrix by an electric field forms the basis of a compact electric field sensor. A thin layer of polymer dispersed liquid crystal is interspersed between two cleaved end faces of multimode fiber. In the absence of an electric field the droplets are randomly oriented. The anisotropy of the refractive index of the liquid crystal causes light to be scattered out of the acceptance angle of the receiving fiber. As the major axis of the indicatrix of the droplets aligns with the field, the anisotropy in refractive index is lowered. The fraction of the light which is scattered is therefore reduced. In this paper we report on the properties of an electric field sensor envisaged for application to overhead transmission lines and utility substations. We discuss linearity, hysteresis, and the effect of temperature on the sensor.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131089738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Optical power provides a novel and often superior way of delivering power to electronic sensors and transducers. Total immunity to lightning and other electromagnetic interference comes from the use of fiber optics to provide power and data communication. The key element in any optically powered sensor or transducer is a photovoltaic power converter developed by Photonic. This device converts light into electrical energy for powering of the sensor and associated circuitry. Pertinent design issues include, choice of light source, minimization of power consumption, single vs. dual fiber, data protocol and level of integration. In addition to a discussion of these issues, a brief outlook on the future of optically powered systems is presented.
{"title":"Optically powered sensors: are they really fiber optic sensors?","authors":"J. Werthen, A. Andersson, Ta C. Wu","doi":"10.1117/12.245576","DOIUrl":"https://doi.org/10.1117/12.245576","url":null,"abstract":"Optical power provides a novel and often superior way of delivering power to electronic sensors and transducers. Total immunity to lightning and other electromagnetic interference comes from the use of fiber optics to provide power and data communication. The key element in any optically powered sensor or transducer is a photovoltaic power converter developed by Photonic. This device converts light into electrical energy for powering of the sensor and associated circuitry. Pertinent design issues include, choice of light source, minimization of power consumption, single vs. dual fiber, data protocol and level of integration. In addition to a discussion of these issues, a brief outlook on the future of optically powered systems is presented.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126554056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pacific Northwest Laboratory (PNL) has fabricated cerium-activated lithium silicate glass scintillating fiber waveguide neutron sensors via a hot-downdraw process. These fibers typically have a transmission length (e-1 length) of greater than 2 meters. The underlying physics of, the properties of, and selected devices incorporating these fibers are described. These fibers constitute an enabling technology for a wide variety of neutron sensors.
{"title":"Variety of neutron sensors based on scintillating glass waveguides","authors":"M. Bliss, R. A. Craig","doi":"10.1117/12.207759","DOIUrl":"https://doi.org/10.1117/12.207759","url":null,"abstract":"Pacific Northwest Laboratory (PNL) has fabricated cerium-activated lithium silicate glass scintillating fiber waveguide neutron sensors via a hot-downdraw process. These fibers typically have a transmission length (e-1 length) of greater than 2 meters. The underlying physics of, the properties of, and selected devices incorporating these fibers are described. These fibers constitute an enabling technology for a wide variety of neutron sensors.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"458 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132832974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper discusses the different methods of fabricating fiber gratings, the different types of fiber gratings and fiber grating devices, and their connection with laser diodes and fiber lasers. We then discuss the fiber grating as a sensor, its sensitivity to different measurands, methods of decoding the sensor response, multiplexing the sensors, and finally their high temperature limitations. Specific references to the materials presented are very numerous and have been omitted. A short list of review papers on fiber gratings is given at the end of the paper. These review papers have more extensive reference lists for many of the developments covered here.
{"title":"Fiber optic grating technology","authors":"W. Morey","doi":"10.1117/12.207762","DOIUrl":"https://doi.org/10.1117/12.207762","url":null,"abstract":"This paper discusses the different methods of fabricating fiber gratings, the different types of fiber gratings and fiber grating devices, and their connection with laser diodes and fiber lasers. We then discuss the fiber grating as a sensor, its sensitivity to different measurands, methods of decoding the sensor response, multiplexing the sensors, and finally their high temperature limitations. Specific references to the materials presented are very numerous and have been omitted. A short list of review papers on fiber gratings is given at the end of the paper. These review papers have more extensive reference lists for many of the developments covered here.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128600471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Optical fibers are finding increasing application in feedback and control systems, medical, industrial, illumination and imaging applications, discrete, as well as distributed sensors and networks. In addition to a course in optical fiber principles and components, a fiber optic systems and applications course designed for both electronics and optical engineering technology students has been created at the Oregon Institute of Technology, in the Laser Optical Engineering Technology (LOET) Department. The systems and applications course is designed to illustrate the benefits of using fibers in communications and sensing, as well as to provide hands-on exposure to concepts of test, measurement, and calibration of fiber-optic components and instrumentation. In the laboratories of both courses, optical fiber sensor experiments are used to teach such concepts as selection and testing of components, design and assembly of transducers, system integration, testing, characterization, and optimization. These two mandatory courses provide an excellent introduction to optical fiber technology and applications. The courses exist primarily due to an NSF-OIT grant, however, companies have made significant contributions of hardware to the program. As a result, over $350 K of fiber optics components and instrumentation now are available for senior-students' use, to develop unique, year-long projects.
{"title":"Fiber optic sensors in the laser optical engineering technology laboratories at the Oregon Institute of Technology","authors":"J. Corones, R. Pierce","doi":"10.1117/12.207750","DOIUrl":"https://doi.org/10.1117/12.207750","url":null,"abstract":"Optical fibers are finding increasing application in feedback and control systems, medical, industrial, illumination and imaging applications, discrete, as well as distributed sensors and networks. In addition to a course in optical fiber principles and components, a fiber optic systems and applications course designed for both electronics and optical engineering technology students has been created at the Oregon Institute of Technology, in the Laser Optical Engineering Technology (LOET) Department. The systems and applications course is designed to illustrate the benefits of using fibers in communications and sensing, as well as to provide hands-on exposure to concepts of test, measurement, and calibration of fiber-optic components and instrumentation. In the laboratories of both courses, optical fiber sensor experiments are used to teach such concepts as selection and testing of components, design and assembly of transducers, system integration, testing, characterization, and optimization. These two mandatory courses provide an excellent introduction to optical fiber technology and applications. The courses exist primarily due to an NSF-OIT grant, however, companies have made significant contributions of hardware to the program. As a result, over $350 K of fiber optics components and instrumentation now are available for senior-students' use, to develop unique, year-long projects.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"283 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116089464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel fiber optic-based probe for the identification of pure and contaminated solids has been developed. Ultimately, this probe is to be used to characterize the make-up and degree of contamination of hazardous waste sites as a preliminary step in the clean-up process. The transmission range of zirconium fluoride fibers allows for the measurement of fundamental stretching frequencies in the mid-infrared (MIR) region as well as overtone and combination bands in the near-infrared (NIR) region. This provides a substantial increase of the measurable concentration range of this MIR/NIR system with respect to systems which can measure only MIR or NIR information. The spectra of samples measured using this fiber optic system is compared to spectra measured in a standard in-compartment diffuse reflectance accessory. The spectra are evaluated in terms of signal-to-noise, measurement time, and detection limits.
{"title":"Application of a zirconium fluoride fiber optic diffuse reflectance probe for the remote identification of solids","authors":"N. Chaffin, I. Lewis, P. Griffiths","doi":"10.1117/12.207748","DOIUrl":"https://doi.org/10.1117/12.207748","url":null,"abstract":"A novel fiber optic-based probe for the identification of pure and contaminated solids has been developed. Ultimately, this probe is to be used to characterize the make-up and degree of contamination of hazardous waste sites as a preliminary step in the clean-up process. The transmission range of zirconium fluoride fibers allows for the measurement of fundamental stretching frequencies in the mid-infrared (MIR) region as well as overtone and combination bands in the near-infrared (NIR) region. This provides a substantial increase of the measurable concentration range of this MIR/NIR system with respect to systems which can measure only MIR or NIR information. The spectra of samples measured using this fiber optic system is compared to spectra measured in a standard in-compartment diffuse reflectance accessory. The spectra are evaluated in terms of signal-to-noise, measurement time, and detection limits.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"351 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115971856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A novel technique of measuring liquid viscosity and air mass flow using forward light scattering from an optical fiber is being presented. The sensing principle is based on the fact that the frequency response of a partially submerged vibrating fiber probe is sensitive to viscosity and mass flow of the fluid. The viscosity and mass flow are determined by measuring the vibration of a sinusoidally excited taunted optical fiber under different flow conditions. The sensor is found to exhibit an excellent sensitivity for measuring other viscosity (liquid approximately 0.1 cP) and flow (air approximately 0.1 m/s). The sensor is also found to exhibit a high S/N ratio (> 50 dB) and stability without having any signal amplification or feedback in the system.
{"title":"Fluid-viscosity and mass-flow sensor using forward light scattering","authors":"Wei-Chih Wang, S. Yee, P. Reinhall","doi":"10.1117/12.207760","DOIUrl":"https://doi.org/10.1117/12.207760","url":null,"abstract":"A novel technique of measuring liquid viscosity and air mass flow using forward light scattering from an optical fiber is being presented. The sensing principle is based on the fact that the frequency response of a partially submerged vibrating fiber probe is sensitive to viscosity and mass flow of the fluid. The viscosity and mass flow are determined by measuring the vibration of a sinusoidally excited taunted optical fiber under different flow conditions. The sensor is found to exhibit an excellent sensitivity for measuring other viscosity (liquid approximately 0.1 cP) and flow (air approximately 0.1 m/s). The sensor is also found to exhibit a high S/N ratio (> 50 dB) and stability without having any signal amplification or feedback in the system.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"539 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133792475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fiber optic sensors offer a series of important advantages with respect to alternative technologies including immunity to electromagnetic interference, small size, light weight, long and short gage length options, the ability to be multiplexed in large numbers and environmental ruggedness. These characteristics make them ideal for many aerospace and natural smart structure applications that are overviewed in this paper.
{"title":"Fiber optic smart structures for aerospace and natural applications","authors":"E. Udd","doi":"10.1117/12.207745","DOIUrl":"https://doi.org/10.1117/12.207745","url":null,"abstract":"Fiber optic sensors offer a series of important advantages with respect to alternative technologies including immunity to electromagnetic interference, small size, light weight, long and short gage length options, the ability to be multiplexed in large numbers and environmental ruggedness. These characteristics make them ideal for many aerospace and natural smart structure applications that are overviewed in this paper.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116798659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ultrasonic sensors and generators based on fiber-optic systems are described. It is shown that intrinsic fiber optic Fabry-Perot ultrasound sensors that are embedded in a structure can be stabilized by actively tuning the laser frequency. The need for this method of stabilization is demonstrated by detecting piezoelectric transducer-generated ultrasonic pulses in the presence of low frequency dynamic strains that are intentionally induced to cause sensor drift. The actively stabilized embedded fiber optic Fabry-Perot sensor is also shown to have sufficient sensitivity to detect ultrasound that is generated in the interior of a structure by means of a high-power optical fiber that pipes energy from a pulsed laser to an embedded generator of ultrasound.
{"title":"Embedded fiber optic ultrasonic sensors and generators","authors":"J. Dorighi, S. Krishnaswamy, J. Achenbach","doi":"10.1117/12.207765","DOIUrl":"https://doi.org/10.1117/12.207765","url":null,"abstract":"Ultrasonic sensors and generators based on fiber-optic systems are described. It is shown that intrinsic fiber optic Fabry-Perot ultrasound sensors that are embedded in a structure can be stabilized by actively tuning the laser frequency. The need for this method of stabilization is demonstrated by detecting piezoelectric transducer-generated ultrasonic pulses in the presence of low frequency dynamic strains that are intentionally induced to cause sensor drift. The actively stabilized embedded fiber optic Fabry-Perot sensor is also shown to have sufficient sensitivity to detect ultrasound that is generated in the interior of a structure by means of a high-power optical fiber that pipes energy from a pulsed laser to an embedded generator of ultrasound.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125088624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fiber optic sensors have very attractive features for industrial applications. Because they use nonconducting glass instead of wires they can operate in high electromagnetic field environments and explosion hazard areas. The expectations of the 1980s were that fiber optic sensor usage would be over $100 M per year in 1993; actual sales were under $20 M. The order-of-magnitude error was in part due to forecasting methodology and in part due to users not accepting the new sensor technology to replace traditional sensors. To understand the difference between predicted and actual sales, 15 studies generated in the mid 1980s were examined and compared with actual industry revenues in 1993. General trends in sensor development were examined by looking at published papers. Fiber optic sensor papers now account for about 30% of all fiber optic papers published with the fraction growing. Industry needs were examined by surveying sensor applications engineers in chemical process control, industrial companies, and electric power. A 55% reply rate was achieved. Sensor characteristics most desired were reliability and stability; cost and size were not considered as important.
{"title":"Fiber optic sensor markets: boom or bust?","authors":"G. Mitchell","doi":"10.1117/12.207755","DOIUrl":"https://doi.org/10.1117/12.207755","url":null,"abstract":"Fiber optic sensors have very attractive features for industrial applications. Because they use nonconducting glass instead of wires they can operate in high electromagnetic field environments and explosion hazard areas. The expectations of the 1980s were that fiber optic sensor usage would be over $100 M per year in 1993; actual sales were under $20 M. The order-of-magnitude error was in part due to forecasting methodology and in part due to users not accepting the new sensor technology to replace traditional sensors. To understand the difference between predicted and actual sales, 15 studies generated in the mid 1980s were examined and compared with actual industry revenues in 1993. General trends in sensor development were examined by looking at published papers. Fiber optic sensor papers now account for about 30% of all fiber optic papers published with the fraction growing. Industry needs were examined by surveying sensor applications engineers in chemical process control, industrial companies, and electric power. A 55% reply rate was achieved. Sensor characteristics most desired were reliability and stability; cost and size were not considered as important.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124241486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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