P. Fuhr, B. MacCraith, D. Huston, Mario Guerrina, M. Nelson
The use of chloride-based deicing agents to help clear US highways of roadway hazards leads to associated chemical related problems. Fouling of local rivers and streams due to runoff of the water borne chlorides is significant and has contributed to local ordances are attempting to force state agencies to reduce, if not eliminate, the use of these chlorides. With respect to the corrosion aspects of chloride application, cracks that occur in the roadway/bridge pavement allow water to seep into the pavement carrying the chloride to the rebar with the resultant increase in corrosion. The costs of this corrosion are considerable and have led to the widespread use of chloride/water impermeable membranes on roadways and especially within bridges. Fiber optic sensor have repeatedly been shown to provide measurement capabilities of parameters within such reinforced concrete structures. Development of a fiber optic chloride sensors capable of being embedded within a roadway or bridge deck is reported.
{"title":"Fiber optic chloride sensing: if corrosion's the problem, chloride sensing is the key","authors":"P. Fuhr, B. MacCraith, D. Huston, Mario Guerrina, M. Nelson","doi":"10.1117/12.285596","DOIUrl":"https://doi.org/10.1117/12.285596","url":null,"abstract":"The use of chloride-based deicing agents to help clear US highways of roadway hazards leads to associated chemical related problems. Fouling of local rivers and streams due to runoff of the water borne chlorides is significant and has contributed to local ordances are attempting to force state agencies to reduce, if not eliminate, the use of these chlorides. With respect to the corrosion aspects of chloride application, cracks that occur in the roadway/bridge pavement allow water to seep into the pavement carrying the chloride to the rebar with the resultant increase in corrosion. The costs of this corrosion are considerable and have led to the widespread use of chloride/water impermeable membranes on roadways and especially within bridges. Fiber optic sensor have repeatedly been shown to provide measurement capabilities of parameters within such reinforced concrete structures. Development of a fiber optic chloride sensors capable of being embedded within a roadway or bridge deck is reported.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123855484","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 neutron spectrometer is a device that measures the spectrum of the kinetic energy of neutrons. There are numerous applications that can profitably use a compact neutron spectrometer. For instance, fast neutron resonance radiography requires sufficiently high resolution (several percent) to identify the absorption spectra of carbon, nitrogen and oxygen nuclei for incident neutrons in the thermal to 5 MeV range. In the nuclear arms-control arena, a device that can collect neutron spectral information without revealing design information would have considerable value for treaty verification. Conventional neutron spectrometers operate on a time-of-flight (TOF) basis. Neutrons of interest range in energy from thermal energy (0.025 eV) to a few MeV for special nuclear material and from ca. 100 KeV to 5 MeV for identification of explosives. A thermal neutron has a speed of ca. 2,000 mis; a 1 MeV neutron has a speed of ca. 13,000 km/sec. A TOF spectrometer has a series of choppers, each turning at different speeds, that pass only those neutrons in a given energy (velocity) range; the velocity cohort that is allowed to pass through the spectrometer and be counted is selected by varying the relative speeds ofrotation. Thus, the TOF spectrometer is, by necessity, large (meters to tens of meters). In addition, only a small fraction of all the incident neutrons are measured during any given time interval. That is, the TOF spectrometer makes very inefficient use of the neutron flux. We will describe a spectrometer that has been made practical by the development of neutron-sensitive scintillating fibers. 1-s This concept is "work-in-progress" but the results of a simple theoretical test are reported here.
{"title":"Spectroscopy without a spectrometer","authors":"M. Bliss, R. A. Craig, D. S. Sunberg","doi":"10.1117/12.285605","DOIUrl":"https://doi.org/10.1117/12.285605","url":null,"abstract":"A neutron spectrometer is a device that measures the spectrum of the kinetic energy of neutrons. There are numerous applications that can profitably use a compact neutron spectrometer. For instance, fast neutron resonance radiography requires sufficiently high resolution (several percent) to identify the absorption spectra of carbon, nitrogen and oxygen nuclei for incident neutrons in the thermal to 5 MeV range. In the nuclear arms-control arena, a device that can collect neutron spectral information without revealing design information would have considerable value for treaty verification. Conventional neutron spectrometers operate on a time-of-flight (TOF) basis. Neutrons of interest range in energy from thermal energy (0.025 eV) to a few MeV for special nuclear material and from ca. 100 KeV to 5 MeV for identification of explosives. A thermal neutron has a speed of ca. 2,000 mis; a 1 MeV neutron has a speed of ca. 13,000 km/sec. A TOF spectrometer has a series of choppers, each turning at different speeds, that pass only those neutrons in a given energy (velocity) range; the velocity cohort that is allowed to pass through the spectrometer and be counted is selected by varying the relative speeds ofrotation. Thus, the TOF spectrometer is, by necessity, large (meters to tens of meters). In addition, only a small fraction of all the incident neutrons are measured during any given time interval. That is, the TOF spectrometer makes very inefficient use of the neutron flux. We will describe a spectrometer that has been made practical by the development of neutron-sensitive scintillating fibers. 1-s This concept is \"work-in-progress\" but the results of a simple theoretical test are reported here.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134316059","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}
The use of a focused ion beam (FIB) to fabricate novel fiber optic structures is described. Using a FIB in either the ion milling mode or deposition mode a large variation in the index of refraction may be introduced in the optical fiber. With a potential beam size as small as 0.02 micrometers , the FIB process provides the ability to both expand the variety and reduce the size of structures that maybe embedded in optical fiber. For example, estimates indicate that a 20 groove Bragg grating coupled to 10 percent of the guided more energy can achieve a maximum 98 percent reflectivity. CUrrent drawbacks of the FIB process include slow production time and high production cost.
{"title":"New method for making fiber optic Bragg gratings","authors":"B. A. Ferguson, R. A. Young","doi":"10.1117/12.285593","DOIUrl":"https://doi.org/10.1117/12.285593","url":null,"abstract":"The use of a focused ion beam (FIB) to fabricate novel fiber optic structures is described. Using a FIB in either the ion milling mode or deposition mode a large variation in the index of refraction may be introduced in the optical fiber. With a potential beam size as small as 0.02 micrometers , the FIB process provides the ability to both expand the variety and reduce the size of structures that maybe embedded in optical fiber. For example, estimates indicate that a 20 groove Bragg grating coupled to 10 percent of the guided more energy can achieve a maximum 98 percent reflectivity. CUrrent drawbacks of the FIB process include slow production time and high production cost.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1997-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131529227","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}
In this paper, a novel optical sensor using surface plasmon resonance in a symmetrical planar lightpipe is introduced. The new design utilizes a microscope slide with beveled ends as the sensor substrate. Collimated TM polarized white light is used to interrogate the sensing surface at a single angle. Preliminary experimental results for glycerol solutions from 0.6%wt to 16%wt demonstrate a concentration sensitivity of 3.4 multiplied by 10-4 by weight. The corresponding refractive index sensitivity is estimated as 4 by 10-5.
{"title":"Optical lightpipe sensor based on surface plasmon resonance","authors":"S. Shen, K. Johnston, S. Yee","doi":"10.1117/12.245579","DOIUrl":"https://doi.org/10.1117/12.245579","url":null,"abstract":"In this paper, a novel optical sensor using surface plasmon resonance in a symmetrical planar lightpipe is introduced. The new design utilizes a microscope slide with beveled ends as the sensor substrate. Collimated TM polarized white light is used to interrogate the sensing surface at a single angle. Preliminary experimental results for glycerol solutions from 0.6%wt to 16%wt demonstrate a concentration sensitivity of 3.4 multiplied by 10-4 by weight. The corresponding refractive index sensitivity is estimated as 4 by 10-5.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"2872 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131153836","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}
Designs of fiber optic chemical sensors are reviewed. Two basic types of sensors are described. The first is a reservoir sensor for determining chloroform based on vapor transport and fluorometric detection. The second type of sensor is a renewable reagent sensor based on vacuum aspiration of samples. Application of this sensor to the fluorometric determination of aluminum and the chemiluminescence determination of chromium is described.
{"title":"Fiber optic chemical sensors for volatile organics and metal ions","authors":"J. Ingle, J. Louch, R. Waddle, E. V. Siemion","doi":"10.1117/12.245573","DOIUrl":"https://doi.org/10.1117/12.245573","url":null,"abstract":"Designs of fiber optic chemical sensors are reviewed. Two basic types of sensors are described. The first is a reservoir sensor for determining chloroform based on vapor transport and fluorometric detection. The second type of sensor is a renewable reagent sensor based on vacuum aspiration of samples. Application of this sensor to the fluorometric determination of aluminum and the chemiluminescence determination of chromium is described.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"40 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":"123211251","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}
Analysis and results of experiments concerning all-fiber passive demodulation of fiber Bragg grating sensors using a many-cycle directional coupler are reported here. The principle of operation is based on the fast wavelength response of a fused tapered 2 by 2 directional coupler pulled through many coupling cycles. The coupler's splitting ratio is then sensitive to small changes in the reflected Bragg wavelength. A design rule to allow the selection and fabrication of a coupler with the desired response has been developed, and the coupler splitting ratio linearity with wavelength is also examined. Because such directional couplers may be readily tailor-made by choosing the number of coupling cycles the coupler is pulled through during fabrication, this approach makes possible a range of sensitivities and wavelengths. Problems encountered with highly sensitive devices due to polarization dependent splitting are also discussed.
{"title":"All-fiber grating sensors employing many-cycle directional couplers","authors":"R. Kenny","doi":"10.1117/12.245582","DOIUrl":"https://doi.org/10.1117/12.245582","url":null,"abstract":"Analysis and results of experiments concerning all-fiber passive demodulation of fiber Bragg grating sensors using a many-cycle directional coupler are reported here. The principle of operation is based on the fast wavelength response of a fused tapered 2 by 2 directional coupler pulled through many coupling cycles. The coupler's splitting ratio is then sensitive to small changes in the reflected Bragg wavelength. A design rule to allow the selection and fabrication of a coupler with the desired response has been developed, and the coupler splitting ratio linearity with wavelength is also examined. Because such directional couplers may be readily tailor-made by choosing the number of coupling cycles the coupler is pulled through during fabrication, this approach makes possible a range of sensitivities and wavelengths. Problems encountered with highly sensitive devices due to polarization dependent splitting are also discussed.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"470 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":"114697312","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 gratings have the potential to be used to support a wide variety of strain measurement applications. These applications include low cost longitudinal strain measurements at temperature ranges up to 800 degrees C, high performance multiaxis strain sensing and integrated strain measurements over long distances. In many cases these applications may require the unique properties associated with fiber optic sensors and in particular fiber optic gratings including small size, the ability to be embedded in a wide variety of materials, high immunity to electromagnetic interference and ease of multiplexing. This paper reviews and summarizes ongoing efforts to apply fiber optic grating technology to a variety of applications requiring the measurement of strain.
{"title":"Advanced strain measurement applications of fiber optic grating sensors","authors":"E. Udd","doi":"10.1117/12.245580","DOIUrl":"https://doi.org/10.1117/12.245580","url":null,"abstract":"Fiber optic gratings have the potential to be used to support a wide variety of strain measurement applications. These applications include low cost longitudinal strain measurements at temperature ranges up to 800 degrees C, high performance multiaxis strain sensing and integrated strain measurements over long distances. In many cases these applications may require the unique properties associated with fiber optic sensors and in particular fiber optic gratings including small size, the ability to be embedded in a wide variety of materials, high immunity to electromagnetic interference and ease of multiplexing. This paper reviews and summarizes ongoing efforts to apply fiber optic grating technology to a variety of applications requiring the measurement of strain.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"67 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":"126699592","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}
We investigated the use of wavelength compensated coupler sensors and etched optical fiber strain sensors to provide an economical on-board load indicator for passenger vehicles. Cost considerations favored the etched fiber sensor. Manufactured sensors were evaluated experimentally by straining them on a cantilever beam. For strain smaller than 600 microstrain the output of a 10 segment sensor was linear with a typical gauge factor of minus 57. Bending losses in the fiber sensor became more pronounced for larger strain. Proper weighting of the outputs of the front and back sensors on the vehicle ensures a monotonic relationship between the sensor output and load. Difference-over-sum processing minimizes the effects of sensitivity to common- mode perturbations such as temperature and source intensity changes.
{"title":"Application of etched fiber strain gauges to low-cost on-board vehicle load monitoring","authors":"B. Lacquet, P. Swart, A. Kotze","doi":"10.1117/12.245577","DOIUrl":"https://doi.org/10.1117/12.245577","url":null,"abstract":"We investigated the use of wavelength compensated coupler sensors and etched optical fiber strain sensors to provide an economical on-board load indicator for passenger vehicles. Cost considerations favored the etched fiber sensor. Manufactured sensors were evaluated experimentally by straining them on a cantilever beam. For strain smaller than 600 microstrain the output of a 10 segment sensor was linear with a typical gauge factor of minus 57. Bending losses in the fiber sensor became more pronounced for larger strain. Proper weighting of the outputs of the front and back sensors on the vehicle ensures a monotonic relationship between the sensor output and load. Difference-over-sum processing minimizes the effects of sensitivity to common- mode perturbations such as temperature and source intensity changes.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"18 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":"121143280","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}
C. M. Lawrence, D. Nelson, E. A. Fuchs, J. Spingarn, T. E. Bennett
Sandia National Laboratories in Livermore, Calif. and the Mechanical Engineering Department of Stanford University are involved in fiber optic sensor research and development for manufacturing process monitoring, smart materials, and other applications. Projects at Sandia and Stanford involving both embedded and surface mounted fiber optic strain and temperature sensors have demonstrated the desirability of this technology. This paper presents an overview of the fiber optic sensing capabilities at Sandia and a summary of the projects currently in progress.
{"title":"Fiber optic sensors at Sandia National Laboratories","authors":"C. M. Lawrence, D. Nelson, E. A. Fuchs, J. Spingarn, T. E. Bennett","doi":"10.1117/12.245586","DOIUrl":"https://doi.org/10.1117/12.245586","url":null,"abstract":"Sandia National Laboratories in Livermore, Calif. and the Mechanical Engineering Department of Stanford University are involved in fiber optic sensor research and development for manufacturing process monitoring, smart materials, and other applications. Projects at Sandia and Stanford involving both embedded and surface mounted fiber optic strain and temperature sensors have demonstrated the desirability of this technology. This paper presents an overview of the fiber optic sensing capabilities at Sandia and a summary of the projects currently in progress.","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":"133821428","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}
Thanks to the growth of the fiber optics telecommunication industry, fiber optic components have become less expensive, more reliable and well known by potential fiber optic sensor users. LEDs, optical fibers, couplers and connectors are now widely distributed and are the building blocks for the fiber optic sensor manufacturer. Additionally, the huge demand in consumer electronics of the past 10 years has provided the manufacturer with cheap and powerful programmable logic components which reduce the development time as well as the cost of the associated instrumentation. This market trend has allowed Photonetics to develop, manufacture and sell fiber optic sensors for the last 10 years. The company contribution in the fields of fiber optic gyros (4 licenses sold world wide), white light interferometry and fiber optic sensor networks is widely recognized. Moreover, its 1992 acquisition of some of the assets of Metricor Inc., greatly reinforced its position and allowed it to pursue new markets. Over the past four years, Photonetics has done an important marketing effort to better understand the need of its customers. The result of this research has fed R&D efforts towards a new generation instrument, the Metricor 2000, better adapted to the expectations of fiber optic sensors users, thanks to its unique features: (1) universality -- the system can accept more than 20 different sensors (T, P, RI, . . .). (2) scalability -- depending on the customer needs, the system can be used with 1 to 64 sensors. (3) performance -- because of its improved design, overall accuracies of 0.01% FS can be reached. (4) versatility -- its modular design enables a fast and easy custom design for specific applications. This paper presents briefly the Metricor 2000 and its family of FO probes. Then, it describes two fiber optic sensing (FOS) applications/markets where FOS have proven to be very useful.
{"title":"Industrial applications of fiber optic sensing","authors":"F. Desforges, Robert Blocksidge","doi":"10.1117/12.245575","DOIUrl":"https://doi.org/10.1117/12.245575","url":null,"abstract":"Thanks to the growth of the fiber optics telecommunication industry, fiber optic components have become less expensive, more reliable and well known by potential fiber optic sensor users. LEDs, optical fibers, couplers and connectors are now widely distributed and are the building blocks for the fiber optic sensor manufacturer. Additionally, the huge demand in consumer electronics of the past 10 years has provided the manufacturer with cheap and powerful programmable logic components which reduce the development time as well as the cost of the associated instrumentation. This market trend has allowed Photonetics to develop, manufacture and sell fiber optic sensors for the last 10 years. The company contribution in the fields of fiber optic gyros (4 licenses sold world wide), white light interferometry and fiber optic sensor networks is widely recognized. Moreover, its 1992 acquisition of some of the assets of Metricor Inc., greatly reinforced its position and allowed it to pursue new markets. Over the past four years, Photonetics has done an important marketing effort to better understand the need of its customers. The result of this research has fed R&D efforts towards a new generation instrument, the Metricor 2000, better adapted to the expectations of fiber optic sensors users, thanks to its unique features: (1) universality -- the system can accept more than 20 different sensors (T, P, RI, . . .). (2) scalability -- depending on the customer needs, the system can be used with 1 to 64 sensors. (3) performance -- because of its improved design, overall accuracies of 0.01% FS can be reached. (4) versatility -- its modular design enables a fast and easy custom design for specific applications. This paper presents briefly the Metricor 2000 and its family of FO probes. Then, it describes two fiber optic sensing (FOS) applications/markets where FOS have proven to be very useful.","PeriodicalId":293004,"journal":{"name":"Pacific Northwest Fiber Optic Sensor","volume":"74 1-2 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":"134150749","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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