Permanent and transient resonances thermally induced in optical fibre Bragg gratings

1995 ◽  
Vol 31 (12) ◽  
pp. 1007-1009 ◽  
Author(s):  
M. Janos ◽  
J. Canning
Keyword(s):  
Optical Fibre ◽  
Bragg Gratings ◽  
Thermally Induced ◽  
Fibre Bragg Gratings

Optical fibre Bragg gratings for high temperature sensing

2009 ◽  
Author(s):  
J. Canning ◽  
M. Stevenson ◽  
K. Cook ◽  
M. Aslund ◽  
W. Ecke ◽  
...  
Keyword(s):  
High Temperature ◽  
Optical Fibre ◽  
Bragg Gratings ◽  
Temperature Sensing ◽  
Fibre Bragg Gratings

scholarly journals The Use of Fibre Optic Sensors for Damage Detection and Location in Structural Materials

2004 ◽  
Vol 1-2 ◽  
pp. 191-196 ◽  
Author(s):  
G. Thursby ◽  
B. Sorazu ◽  
D. Betz ◽  
M. Staszewski ◽  
B. Culshaw
Keyword(s):  
Wave Propagation ◽  
Optical Fibre ◽  
Lamb Wave ◽  
Lamb Waves ◽  
Fibre Length ◽  
Bragg Gratings ◽  
Maximum Sensitivity ◽  
Fibre Bragg Grating ◽  
Integrated Sensor ◽  
Fibre Bragg Gratings

The measurement of changes in the properties of ultrasonic Lamb waves propagating through structural material has frequently been proposed as a method for the detection of damage. In this paper we describe work that uses optical fibre sensors to detect the Lamb waves and show that the directional properties of these sensors allow us to not only detect damage, but also to locate it. We look at two types of optical fibre sensor, a polarimetric sensor and the fibre Bragg grating. The polarimetric sensor measures the change in birefringence of a fibre caused by the pressure wave of the ultrasound acting upon it. This is an integrated sensor since the fibre length bonded to the sample needs to be greater than the ultrasonic wavelength in order to obtain the required sensitivity. The maximum sensitivity of this sensor is when the fibre is positioned normal to the direction of wave propagation. Fibre Bragg gratings are essentially point sensors since the grating length needs to be a fraction of the ultrasound wavelength to obtain maximum sensitivity. Ultrasound is detected mainly through the in-plane strain it produces and maximum sensitivity is therefore produced when the grating is aligned parallel to the direction of wave propagation. Holes drilled into sample plates can be detected using both type of sensor by examining the changes in either the transmitted Lamb wave or through detection of the reflections produced by the hole. The sensitivity of the technique is shown to be determined by the relative positions of the acoustic source, the hole and the sensor. If we use fibre Bragg gratings in a rosette configuration (i.e. 3 gratings forming an equilateral triangle) then the direction of the Lamb wave can be determined using the directional sensitivities of the gratings. Using two such rosettes allows us to calculate the source of the wave from the intersection of two of these directions. If the source of the wave is the hole (which acts as a passive source), then the location of that hole can be determined.

Monitoring of Lri Process by Optical Fibre Bragg Gratings

2007 ◽  
pp. 641-642
Author(s):  
S. Vacher ◽  
J. Molimard ◽  
A. Vautrin ◽  
H. Gagnaire ◽  
P. Henrat
Keyword(s):  
Optical Fibre ◽  
Bragg Gratings ◽  
Fibre Bragg Gratings

scholarly journals Reliability of fibre Bragg gratings in polymer optical fibre

2006 ◽  
Author(s):  
H. Dobb ◽  
K. Carroll ◽  
D. J. Webb ◽  
K. Kalli ◽  
M. Komodromos ◽  
...  
Keyword(s):  
Optical Fibre ◽  
Bragg Gratings ◽  
Fibre Bragg Gratings
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