Optical fibre grating Bragg

As mentioned earlier, optical fibres with Bragg gratings can also be applied as pressure and strain sensors. When these fibres are integrated into a mattress or bed sheet, they will be deformed as soon as pressure is exerted on them. The deformation will cause proportional changes in the Bragg wavelength and, hence, the movement can be tracked (Dziuda and Skibniewski, 2014). 

Zhang A P, Tao X M and Tam H Y, Prediction of polarization behavior of twisted optical fibres containing Bragg grating sensors, J. Textile Inst., 2000, Part 3,105-16. 

Those based on the fluorescence lifetime, rather than intensity (e.g. the Ipitek system), allow one to avoid problems of light loss and other factors that could affect calibration, as discussed above. Assessment of tilted Bragg gratings and long-period gratings on optical fibres has shown them to be a probe of cure of the resin as well as being both temperature- and strain-sensitive (Buggy et al, 2007). The complexity of the response of these and fibre-optics based Fabry-Perot interferometers to strain, temperature and refractive index makes it necessary to employ combinations of sensors if measurements of all of these properties are required separately. 

Kuang KSC, Kenny R, Whelan MP, Cantwell WJ, ChaUcer PR. Residual strain measurement and impact response of optical fibre Bragg grating sensors in fibre metal laminates. Smart Mater Struct 2001 10(2) 338—46. http //dx.doi.org/10.1088/0964-1726/10/2/321. 

A stress field applied transversely to the grating modifies the structure of the previously isotropic optical fibre, generating two perpendicular directions with different indices of refraction. For a single Bragg grating spacing... 

Kuang K S C and Cantwell W J (2003), The use of conventional optical fibres and fibre Bragg gratings for damage detection in advanced composite structures - a review , ApplMech Rev, 56, 493-513. doi 10.1115/1.1582883... 

Krebber, K. Habel, W.R., et al. Fiber Bragg grating sensors for monitoring of wind turbine blades. 17th Int. Conf on Optical Fibre Sensors (OFS-17), Bruges, Belgium, SPIEl-Vol. 5855 (2005), pp. 1036-1039... 

Sakamoto Y, Takai K, Takashima I, Imada M (1996) Electrical resistance measurements as a function of composition of palladium-hydrogen(deuterium) systems by a gas phase method. J Phys Condens Matter 8 3399-3411 Schroeder K, Ecke W, WUlsch R (2009) Optical fibre Bragg grating hydrogen sensor based on evanescent-field interaction with palladium thin-film transducer. Opt Lasers Eng 47(10) 1018-1022 Sharma AK, Gupta BD (2007) On the performance of different bimetaUic combinations in surface plasmon resonance based fiber optic sensors. J Appl Phys 101(9) 093111... 

The inscription of permanent Bragg grating can be achieved in the core of an optical fibre by interference of two coherent ultra-violet light beams. The grating thus has a holographically induced refractive index modulation with a period A = sin(0/2), where 6 is the angle between the two writing beams... 

From the experiment above we can confirm that it is reasonable to assume that the deformation of optical fibre contains uniform Bragg grating during the tension and the strain measured is believable. 

Meltz G, Morey W W and Glenn W H, Forming of Bragg grating in optical fibres by a transverse holographic method . Opt. Lett., 1989, 14, 823-5. 

Askins C C, Putnam M A, Williams G M and Friebele E J, Stepped-wavelength optical-fibre Bragg grating arrays fabricated in line on a draw tower . Opt. Lett., 1994,14, 823-4. 

Bernardin J P and Lawandy N M, Dynamics of the formation of Bragg gratings in germanosilicate optical fibres . Opt. Commun., 1990, 79, 194-8. 

Xiong Z, Peng G D, Wu B and Chu P L, Highly tunable Bragg gratings in single-mode polymer optical fibres ,/ Photon. Technol. Lett., 1999,11(3), 352-4. 

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