Rayleigh, Brillouin and Raman scatterings in fibers result from the interaction of photons with local material characteristic features like density, temperature and strain. For example an acoustic/mechanical wave generates a dynamic density variation; such a variation may be affected by local temperature, strain, vibration and birefringence. By detecting changes in the amplitude, frequency and phase of light scattered along a fiber, one can realize a distributed fiber sensor for measuring localized temperature, strain, vibration and birefringence over lengths ranging from meters to one hundred kilometers. Such a measurement can be made in the time domain or frequency domain to resolve location information. With coherent detection of the scattered light one can observe changes in birefringence and beat length for fibers and devices. The progress on state of the art technology for sensing performance, in terms of spatial resolution and limitations on sensing length is reviewed. These distributed sensors can be used for disaster prevention in the civil structural monitoring of pipelines, bridges, dams and railroads. A sensor with centimeter spatial resolution and high precision measurement of temperature, strain, vibration and birefringence can find applications in aerospace smart structures, material processing, and the characterization of optical materials and devices.

Recent progress in distributed fiber optic sensors.

This work presents an overview of progress and developments in the field of fiber optic sensor technology, highlighting the major issues underpinning recent research and illustrating a number of important applications and key areas of effective fiber optic sensor development.

http://snake.persiangig.com/document/sensor1.pdf

Fiber optic sensor technology: an overview

A distributed sensor system for detecting and locating intruders based on the phase-sensitive optical-time-domain reflectometer (/spl phi/-OTDR) is described. The sensing element is a cabled single-mode telecommunications fiber buried along the monitored perimeter. Light pulses from a continuous-wave Er:fiber Fabry-Pe/spl acute/rot laser with a narrow (/spl ap/3 kHz) instantaneous linewidth and low (few kilohertz per second) frequency drift are injected into one end of the fiber, and the backscattered light is monitored with a photodetector. The effect of phase changes resulting from the pressure of the intruder on the ground immediately above the buried fiber are sensed by subtracting a /spl phi/-OTDR trace from an earlier stored trace. In laboratory tests with fiber on reels, the effects of localized phase perturbations induced by a piezoelectric fiber stretcher on /spl phi/-OTDR traces were observed. In field tests, people walking on the ground above a buried fiber cable induced phase shifts of several-/spl pi/ radians.

Distributed fiber-optic intrusion sensor system

This paper reviews the developments of a distributed strain and temperature sensing technique that uses Brillouin scattering in single-mode optical fibers. This technique is based on strain- and temperature-induced changes in the Brillouin frequency shift. Several approaches for measuring the weak Brillouin line are compared. >

Development of a distributed sensing technique using Brillouin scattering

This article reviews the American literature in social science for the period 1975–1992 on the determinants of volunteer participation in programs and associations. It finds that most studies are t...

Determinants of Voluntary Association Participation and Volunteering: A Literature Review:

This book explains physical principles, unique benefits, broad categories, implementation aspects, and performance criteria of distributed optical fiber sensors (DOFS). For each kind of sensor, the book highlights industrial applications, which range from oil and gas production to power line monitoring, plant and process engineering, environmental monitoring, industrial fire and leakage detection, and so on. The text also includes a discussion of such key areas as backscattering, launched power limitations, and receiver sensitivity, as well as a concise historical account of the field’s development.

An Introduction to Distributed Optical Fibre Sensors

The principles of operation, the design, and performance of a fiber-optic temperature-distribution sensor are discussed. The sensor uses optical time-domain reflectometry (OTDR) to detect temperature-induced changes of backscatter power at many separate locations in the fiber. In liquid-core fibers, a sensitivity of 2.3 \times 10^{-2} dB/°C (0.54 percent° C-1) was observed. A measurement accuracy of 1°C with a spatial resoltuion of 1 m is attainable over a fiber length of 100 m.

/pdf/a-distributed-temperature-sensor-based-on-liquid-core-1uosxs9hxm.pdf

A distributed temperature sensor based on liquid-core optical fibers

A new theory of backscattering in single-mode fibers is presented. It allows backscatter waveforms to be predicted for fibers of any refractive-index profile or scattering-loss distribution. The results agree with experimental data and provide confirmation of an earlier, more restricted theory.

/pdf/on-the-theory-of-backscattering-in-single-mode-optical-1sysgjyaa7.pdf

On the theory of backscattering in single-mode optical fibers

An optical time domain reflectometry method of sensing a parameter to be measured in a region of interest comprises launching optical radiation (4) at a probe wavelength into an-optical fibre (5, 6) and producing electrical output signals in response to optical radiation backscattered from the optical fibre (5, 6). In one aspect of the invention the optical fibre comprises first and second sections (5, 6), the second section (6) having a lower intensity threshold for the onset of non-linear effects than the first section (5) and being deployed in the region of interest. Optical radiation (4) at the probe wavelength is launched into the said first section (5) at an intensity lower than the non-linear effects intensity threshold of the first section (5) but higher than the non-linear effects intensity threshold of the second section (6), the attenuation characteristics of the said first section (5) being chosen so that the intensity of the optical radiation (4) at the probe wavelength reaching the second section (6) is below that of the non-linear effects intensity threshold of the said second section (6). In another aspect of the invention the optical fibre comprises first and second sections connected together by a remote amplifier, the gain of the amplifier being selected so as to compensate for attenuation losses in the probe wavelength in the first section.

Optical time-domain reflectometry

A distributed temperature sensor using the Raman line of backscattered light in solid-core optical fibres is reported. A device having a resolution of 1 K over 1 km of fibre and with a spatial resolution of 7.5 m was constructed using a semiconductor source and detector.

/pdf/distributed-temperature-sensing-in-solid-core-fibres-4ys7486zkj.pdf

Distributed temperature sensing in solid-core fibres

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Arthur H. Hartog

Author Tools

Chat about Author