摘要:
Die Erfindung betrifft eine faseroptische Erfassungseinrichtung (10), mit wenigstens einer als Lichtleiter ausgebildeten Faser (12), welche wenigstens einen ersten Längenbereich (14) mit einem ersten Außenumfang und wenigstens einen sich in Längserstreckungsrichtung (22) der Faser (12) an den ersten Längenbereich (14) anschließenden zweiten Längenbereich (16) mit einem gegenüber dem ersten Außenumfang geringeren zweiten Außenumfang aufweist, mit wenigstens einer Schutzhülle (24), in welcher zumindest die Längenbereiche (14, 16) aufgenommen sind, und mit wenigstens einem Sensortandem (28), welches wenigstens ein in den ersten Längenbereich (14) eingeschriebenes erstes Faser-Bragg-Gitter (30) und wenigstens ein in den zweiten Längenbereich (16) eingeschriebenes zweites Faser-Bragg-Gitter (34) aufweist und dazu ausgebildet ist, an einer korrespondierenden Messstelle sowohl eine an der Messstelle herrschende Temperatur als auch wenigstens eine an der Messstelle auftretende und in Längserstreckungsrichtung (22) der Faser (12) wirkende Kraft zu erfassen.
摘要:
Embodiments of the invention provide an improved optical fiber distributed acoustic sensor system that makes use of a specially designed optical fiber to improve overall sensitivity of the system, in some embodiments by a factor in excess of 10. This is achieved by inserting into the fiber weak broadband reflectors periodically along the fiber. The reflectors reflect only a small proportion of the light from the DAS incident thereon back along the fiber, typically in the region of 0.001% to 0.1%, but preferably around 0.01% reflectivity per reflector. In addition, to allow for temperate compensation to ensure that the same reflectivity is obtained if the temperature changes, the reflection bandwidth is relatively broadband i.e. in the region of +/- 3nm from the nominal laser wavelength. In some embodiments the reflectors are formed from a series of fiber Bragg gratings, each with a different center reflecting frequency, the reflecting frequencies and bandwidths of the gratings being selected to provide the broadband reflection. In other embodiments a chirped grating may also be used to provide the same effect. In preferred embodiments, the reflectors are spaced at half the gauge length i.e. the desired spatial resolution of the optical fiber DAS.
摘要:
Apparatus for measuring deformation of an elongate body defining an axis, the apparatus including: an optical fibre arranged relative to the body, the optical fibre including a first strain sensitive optical fibre portion coupled to the body and at least partially aligned at a first angle relative to the axis, and a second strain sensitive optical fibre portion coupled to the body and at least partially aligned at a second angle relative to the axis, the second angle being opposite to the first angle; a radiation source connected to an end of the optical fibre, the radiation source being for supplying electromagnetic radiation to the optical fibre; a sensor connected to an end of the optical fibre, the sensor being for sensing electromagnetic radiation received from the first and second optical fibre portions; and a processing device for determining the deformation of the body using the sensed electromagnetic radiation, the deformation including any axial or torsional deformation.
摘要:
Die Erfindung betrifft einen faseroptischen Sensor (1) mit einem Lichtwellenleiter (12), welcher zumindest einen ersten Kern (11) und einen den ersten Kern (11) umgebenden Mantel (10) aufweist, wobei der erste Kern (11) sich im Wesentlichen über die gesamte Länge des Lichtwellenleiters (12) erstreckt, wobei der Sensor (1) zumindest einen zweiten Kern (2) aufweist, welcher zumindest teilweise vom Mantel (10) umgeben ist, wobei die Längserstreckung des zweiten Kerns (2) geringer ist als die gesamte Länge des Lichtwellenleiters (12) und in den zweiten Kern (2) zumindest ein Bragg-Gitter (231a, 231b, 232) eingebracht ist. Weiterhin betrifft die Erfindung eine Verwendung des faseroptischen Sensors (1).
摘要:
A method and apparatus for predicting the risk of, susceptibility to or potential for corrosion of a metal structure such as a pipe is disclosed. The method comprises detecting the temperature of the metal structure, detecting for the presence of fluid on the metal structure and using the results of the two detections to predict the risk of, susceptibility to or potential for corrosion. The prediction may also rely on prior knowledge of the material from which the metal structure being analysed is made.
摘要:
To detect by means of a long-baseline system the global bending strain of a structure (1), i.e. by detecting the accumulated local bending strains over a distance of at least two metres, detection lines (8, 11), preferably optical fibre lines, which indicate the extent of their elongation by an increased attenuation of the light pulses which run through them, are used. To detect the direction and the extent of the flexure of the structure (1), the latter is closely associated with a model comprising a matrix (13) which follows the flexural bending strains of the structure (1), and at least one, preferably two detection lines (8, 11) suitably located in the matrix cross-section so that their elongation variations and/or the differences between their respective elongation variations are indicative of the flexure of the model, which gives indications on the flexure of the structure (1). The invention is useful in determining the straight or distorted flexure or contraflexure of structures not easily accessible or partially inaccessible, to measure level variations on one or several axes.
摘要:
The present invention is a condition monitoring sensor system for a conveyor belt flight, having a plurality of sensors that are formed from a continuous length of fibre optic cable that runs along at least a portion of the length of the conveyor belt flight. A looped portion of the fibre optic cable is first formed with a comparatively tight bend radius so that the looped portion is adapted to be threaded through the interior diameter of the hollow shaft of at least some of the rollers in the conveyor belt system, for a sufficient distance so that an end portion of the looped portion extends beyond the end of the hollow shaft, and then the end portion of the looped portion is expanded out so that the bend radius is significantly increased, which opens out the end portion of the looped portion, and gives the end portion an increased bend radius which thereby enables a condition monitoring signal to pass through the loop portion without significant signal degradation.
摘要:
Apparatus for measuring deformation of an elongate body defining an axis, the apparatus including: an optical fibre arranged relative to the body, the optical fibre including a first strain sensitive optical fibre portion coupled to the body and at least partially aligned at a first angle relative to the axis, and a second strain sensitive optical fibre portion coupled to the body and at least partially aligned at a second angle relative to the axis, the second angle being opposite to the first angle; a radiation source connected to an end of the optical fibre, the radiation source being for supplying electromagnetic radiation to the optical fibre; a sensor connected to an end of the optical fibre, the sensor being for sensing electromagnetic radiation received from the first and second optical fibre portions; and a processing device for determining the deformation of the body using the sensed electromagnetic radiation, the deformation including any axial or torsional deformation.
摘要:
Sensor shaped to have a frequency response that has less spectral fading than a sensor with a rectangular wrapping pattern, and methods for making such sensors, are disclosed. One such method includes selecting a wrapping pattern comprising multiple layers in which a top layer has a different length than a bottom layer and where the bottom layer is adjacent a mandrel. The method further includes wrapping optical fiber around the mandrel according to the wrapping pattern.