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1. WO2000039549 - A MODULATED FIBRE BRAGG GRATING STRAIN GAUGE ASSEMBLY FOR ABSOLUTE GAUGING OF STRAIN

Publication Number WO/2000/039549
Publication Date 06.07.2000
International Application No. PCT/GB1999/004210
International Filing Date 13.12.1999
Chapter 2 Demand Filed 04.07.2000
IPC
G01D 5/353 2006.01
GPHYSICS
01MEASURING; TESTING
DMEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED BY A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; TRANSFERRING OR TRANSDUCING ARRANGEMENTS NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
5Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
26using optical means, i.e. using infra-red, visible or ultra-violet light
32with attenuation or whole or partial obturation of beams of light
34the beams of light being detected by photocells
353influencing the transmission properties of an optical fibre
G01L 1/24 2006.01
GPHYSICS
01MEASURING; TESTING
LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
1Measuring force or stress, in general
24by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis
CPC
G01D 5/35316
GPHYSICS
01MEASURING; TESTING
DMEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
5Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
26characterised by optical transfer means, i.e. using infra-red, visible, or ultra-violet light
32with attenuation or whole or partial obturation of beams of light
34the beams of light being detected by photocells
353influencing the transmission properties of an optical fibre
35306using an interferometer arrangement
35309using multiple waves interferometer
35316using a Bragg gratings
G01L 1/246
GPHYSICS
01MEASURING; TESTING
LMEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
1Measuring force or stress, in general
24by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis ; using infra-red, visible light, ultra-violet
242the material being an optical fibre
246using integrated gratings, e.g. Bragg gratings
Applicants
  • BAE SYSTEMS PLC [GB/GB]; Warwick House Farnborough Aerospace Centre P.O. Box 87 Farnborough Hampshire GU14 6YU, GB (AllExceptUS)
  • MALVERN, Alan [GB/GB]; GB (UsOnly)
  • ALLSOP, Thomas [GB/GB]; GB (UsOnly)
  • NEAL, Ronald [GB/GB]; GB (UsOnly)
Inventors
  • MALVERN, Alan; GB
  • ALLSOP, Thomas; GB
  • NEAL, Ronald; GB
Agents
  • ROONEY, Paul, Blaise; BAE Systems plc Group IP Dept. Lancaster House, P.O Box 87 Farnborough Aerospace Centre Farnborough, Hampshire GU14 6YU, GB
Priority Data
9828469.824.12.1998GB
Publication Language English (EN)
Filing Language English (EN)
Designated States
Title
(EN) A MODULATED FIBRE BRAGG GRATING STRAIN GAUGE ASSEMBLY FOR ABSOLUTE GAUGING OF STRAIN
(FR) JAUGE DE CONTRAINTE A RESEAU DE BRAGG MODULE A FIBRE FOURNISSANT UNE VALEUR ABSOLUE DES CONTRAINTES
Abstract
(EN)
A modulated fibre Bragg grating strain gauge assembly for absolute gauging of strain including at least one sensor element (1) in the form of a length of optical fibre containing, along part of its length, means for partially reflecting light (1a), means for generating and passing a beam of light (2a) into the sensor element (1) where reflection takes place, which reflection is a sinusoidal intensity variation in wavelength comprising at least two sinusoidal periods such that as the sensor element sustains a change in length resulting from a strain thereon, the reflected intensity varies sinusoidally along the at least two sinusoidal periods, means for receiving and processing the reflected light (2b) at one (1f) and two times (2f) a modulation frequency (1f) applied to the means for generating the beam of light (2a), and means to determine an absolute direction and magnitude of strain from a ratio of the intensity values 1f:2f.
(FR)
L'invention porte sur une jauge de contrainte à réseau de Bragg modulé à fibre fournissant une valeur absolue des contraintes comprenant au moins: un détecteur (1) sous la forme d'un segment de fibre optique muni sur une partie de sa longueur de moyens (1a) réfléchissant partiellement la lumière (1a); des moyens de création et de transfert du faisceau (2a) dans le détecteur où se produit la réflexion qui apparaît comme une variation sinusoïdale d'intensité en fonction de la longueur d'onde sur au moins deux périodes de la sinusoïde, et tels que si le détecteur subit une variation de longueur sous l'effet d'une contrainte, l'intensité réfléchie varie sinusoïdalement sur au moins deux périodes; des moyens de réception et de traitement de la lumière (2b) réfléchie présentant une fois (1f) et deux fois (2f) la fréquence modulée (1f) appliquée au moyen de création (2a) du faisceau lumineux une fréquence modulée; et des moyens de calcul la direction et l'amplitude de la contrainte à partir du rapport 1f:2f des intensités.
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