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Distributed temperature sensing systems (DTS) are optoelectronic devices which measure temperatures by means of optical fibres functioning as linear sensors. Temperatures are recorded along the optical sensor cable, thus not at points, but as a continuous profile. A high accuracy of temperature determination is achieved over great distances. Optoelectronics is the study and application of electronic devices that interact with light. ...
Optical fibers An optical fiber is a transparent thin fiber, usually made of glass or plastic, for transmitting light. ...
A sensor is a technological device or biological organ that detects, or senses, a signal or physical condition. ...
Measuring principle — Raman effect
Physical measurement dimensions, such as temperature or pressure and tensile forces, can affect glass fibres and locally change the characteristics of light transmission in the fibre. As a result of the damping of the light in the quartz glass fibres through scattering, the location of an external physical effect can be determined so that the optical fibre can be employed as a linear sensor. Optical fibres are made from doped quartz glass. Quartz glass is a form of silicon dioxide (SiO2) with amorphous solid structure. Thermal effects induce lattice oscillations within the solid. When light falls onto these thermally excited molecular oscillations, an interaction occurs between the light particles (photons) and the electrons of the molecule. Light scattering, also known as Raman scattering, occurs in the optical fibre. Unlike incident light, this scattered light undergoes a spectral shift by an amount equivalent to the resonance frequency of the lattice oscillation. The light scattered back from the fibre optic therefore contains three different spectral shares: In thermodynamics, temperature is the physical property of a system that underlies the common notions of hot and cold —something that is hotter has the greater temperature. ...
Pressure (symbol: p) is the force per unit area applied on a surface in a direction perpendicular to that surface. ...
In physics, tension is a force on a body directed to produce strain (extension); it can be considered to be negative compression. ...
Damping is any effect, either deliberately engendered or inherent to a system, that tends to reduce the amplitude of oscillations of an oscillatory system. ...
In particle physics, scattering is a class of phenomena by which particles are deflected by collisions with other particles. ...
R-phrases R42 R43 R49 S-phrases S22 S36 S37 S45 S53 Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ...
In quantum physics, the photon (from Greek φως, phÅs, meaning light) is the quantum of the electromagnetic field (light). ...
Raman scattering or the Raman effect is the inelastic scattering of a photon which creates or annihilates an optical phonon. ...
- the Rayleigh scattering with the wavelength of the laser source used,
- the Stokes line components with the higher wavelength in which photons are generated, and
- the anti-Stokes line components with a lower wavelength than the Rayleigh scattering, in which photons are destroyed.
The intensity of the so-called anti-Stokes band is temperature-dependent, while the so-called Stokes band is practically independent of temperature. The local temperature of the optical fibre is derived from the ratio of the anti-Stokes and Stokes light intensities. Rayleigh scattering causing a reddened sky at sunset Rayleigh scattering (named after Lord Rayleigh) is the scattering of light, or other electromagnetic radiation, by particles much smaller than the wavelength of the light. ...
Stokes line is named after Sir George Gabriel Stokes. ...
Measuring principle — OFDR technology Latest DTS evaluation units deploy the method of optical frequency domain reflection (OFDR). The OFDR system provides information on the local characteristic only when the backscatter signal detected during the entire measurement time is measured as a function of frequency in a complex fashion, and then subjected to Fourier transformation. The essential benefits of OFDR technology are the quasi continuous wave mode employed by the laser and the narrow-band detection of the optical back scatter signal, whereby a significantly higher signal to noise ratio is achieved than with conventional pulse technology (OTDR). This technical benefit allows the use of affordable semiconductor laser diodes and electronic assemblies for signal averaging. This is offset by the technically difficult measurement of the Raman scatter light and rather complex signal processing, due to the FFT calculation with higher linearity requirements for the electronic components. The optical frequency domain reflectometry has been developed as a high-resolution measurement process for the characterisation of optical wave guides with length dimensions of just a few millimetres. In contrast, its application for the Raman backscatter measurement was introduced by the company LIOS Technology. The Fourier transform, named after Jean Baptiste Joseph Fourier, is an integral transform that re-expresses a function in terms of sinusoidal basis functions, i. ...
In telecommunication, an optical time domain reflectometer (OTDR) is an optoelectronic instrument used to characterize an optical fiber. ...
FFT may be: Fast Fourier transform Finite Fourier transform, another name for the discrete Fourier transform US Navy hull classification symbol for Reserve Training Frigates Final Fantasy Tactics, a video game. ...
Schematic system structure The temperature measuring system consists of a controller (frequency generator, laser source, optical module, HF mixer, receiver and micro-processor unit) and a quartz glass fibre (fibre optic) as line-shaped temperature sensor. The design is three-channel, since an additional reference channel is required besides the two measurement channels (Anti-Stokes and Stokes). Corresponding to the OFDR system, the power output of the laser runs through the sinus-shaped frequency starting from a starting frequency in the kilohertz range through the ending frequency in the high megahertz range within a measurement time interval with the help of the High Frequency (HF) modulator. The resulting frequency shift is a direct measurement of the local resolution of the reflectometer. The frequency-modulated laser light is connected to the fibre optic-sensor via the optical module. The continuously back-scattered Raman light is spectrally filtered in the optical module and converted into electrical signals by means of photo detectors. Then the measurement signals are amplified and mixed in the Low frequency spectral range (LF range). The Fourier transformation of the averaged LF signals results in the two Raman backscatter curves. The amplitudes of these backscatter curves are proportional to the intensity of the Raman scattering of the viewed location. The fibre temperature along the sensor cable results from the amplitude ratio of the two measurement channels. A signal generator, also known variously as a test signal generator, tone generator (in audio only), waveform generator, or frequency generator is an electronic instrument that generates repeating electronic signals (in either the analog of digital domains). ...
Experiment using a (likely argon) laser. ...
HF or Hf might be an acronym or abbreviation for: High frequency Radio hafnium, a chemical element the chemical formula for Hydrofluoric acid Historisk-filosofisk fakultet, abbr. ...
High frequency (HF) radio frequencies are between 3 and 30 MHz. ...
This article is being considered for deletion in accordance with Wikipedias deletion policy. ...
Applications Distributed Temperature Sensing can be deployed successfully in multiple industrial segments: - Fire Detection in Tunnels and Special Hazard Buildings
- Power Cable and Transmission Line Monitoring (Ampacity Optimisation)
- Oil & Gas Exploration – permanent Downhole Monitoring
- Industrial Induction Furnaces Surveillance
- Integrity of LNG Carriers and Terminals
- Leakage Detection at Dikes and Dams
- Temperature Monitoring in Plant & Process Engineering
American wire gauge (AWG) is used in the United States and other countries as a standard method of denoting wire diameter, especially for non-ferrous, electrically conducting wire. ...
Liquefied natural gas or LNG is natural gas that has been cooled until it becomes liquid, and it is stored in tanks. ...
See also In telecommunication, a time-domain reflectometer (TDR) is an electronic instrument used to characterize and locate faults in metallic cables ( twisted pair, coax). ...
Well logging is a technique used in the oil and gas industry for recording rock and fluid properties to find hydrocarbon zones in the geological formations below the Earths crust. ...
Wellsite Information Transfer Standard Markup Language A POSC facilitated Special Interest Group to develop XML standards for PetroTechnical Data exchange. ...
External links - The Fiber Optic Association
DTS in fire detection - Paper published at International Conference on Automatic Fire Detection (AUBE’04); University of Duisburg; LIOS Technology GmbH
- European Initiative SOLIT - Safety Of Life In Tunnels
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