scholarly journals THE METHOD OF DETECTING INHOMOGENEITIES AND DEFECTS IN MATERIALS USING SENSORS BASED ON THE FIBER BRAGG OPTIC STRUCTURES

2019 ◽  
Vol 9 (3) ◽  
pp. 62-65
Author(s):  
Łukasz Zychowicz
Keyword(s):  
Transmission Spectrum ◽  
Optical Spectrum ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Total Width ◽  
Full Width ◽  
Half Maximum ◽  
Optical Spectrum Analyzer ◽  
Transmission Characteristics ◽  
Main Minimum

The article presents the possibilities of detecting defect in materials using the fiber Bragg gratings (FBG). Steel belts with a thickness of 1 mm were used for the tests: one standard and the others were damaged. The damage was in the form of incisions. The FBG was glued to the sample with epoxy glue along its entire length and elongation by outside force. Based on the transmission spectrum obtained on the Optical Spectrum Analyzer (OSA) the processing characteristics: the main minimum on the transmission characteristics, total width of the spectrum and the full width at half maximum FWHM depending on the FBG strain was determine.

scholarly journals Development of a Shock and Detonation Velocity Measurement System Using Chirped Fiber Bragg Gratings

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1026
Author(s):  
Yohan Barbarin ◽  
Alexandre Lefrançois ◽  
Vincent Chuzeville ◽  
Sylvain Magne ◽  
Laurent Jacquet ◽  
...  
Keyword(s):  
Wave Front ◽  
Detonation Velocity ◽  
Optical Spectrum ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Calibration Procedure ◽  
Light Power ◽  
Front Profile ◽  
Chirped Fiber Bragg Gratings ◽  
Steady Detonation

Dynamic measurements of shock and detonation velocities are performed using long chirped fiber Bragg gratings (CFBGs). Such thin probes, with a diameter of typically 125 µm or even 80 µm can be directly inserted into high-explosive (HE) samples or simply glued laterally. During the detonation, the width of the optical spectrum is continuously reduced by the propagation of the wave-front, which physically shortens the CFBG. The light power reflected back shows a ramp-down type signal, from which the wave-front position is obtained as a function of time, thus yielding a detonation velocity profile. A calibration procedure was developed, with the support of optical simulations, to cancel out the optical spectrum distortions from the different optical components and to determine the wavelength-position transfer function of the CFBG. The fitted slopes of the X–T diagram give steady detonation velocity values which are in very good agreement with the classical measurements obtained from discrete electrical shorting pins (ESP). The main parameters influencing the uncertainties on the steady detonation velocity value measured by CFBG are discussed. To conclude, different HE experimental configurations tested at CEA (Commissariat à l’Energie Atomique et aux Energies Alternatives) are presented: bare cylindrical sticks, wedges for shock-to-detonation transitions (SDT), spheres, a cast-cured stick around a CFBG, and a detonation wave-front profile configuration.

Transmission characteristics of fiber Bragg gratings written in holey fibers corresponding to air-hole size and their application

2006 ◽  
Vol 18 (16) ◽  
pp. 1783-1785 ◽  
Author(s):  
Young-Geun Han ◽  
Young Jun Lee ◽  
Gil Hwan Kim ◽  
Hung Su Cho ◽  
Sang Bae Lee ◽  
...  
Keyword(s):  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Hole Size ◽  
Transmission Characteristics ◽  
Air Hole

Artificially Induced Perturbations in Chirped Magneto-Optical Bragg Gratings

2004 ◽  
Vol 834 ◽  
Author(s):  
Fredrik Jonsson ◽  
Christos Flytzanis
Keyword(s):  
Polarization State ◽  
Bragg Gratings ◽  
Grating Period ◽  
Full Width ◽  
Half Maximum ◽  
Circularly Polarized ◽  
Orthogonal Components ◽  
Order Of Magnitude ◽  
State Selectivity ◽  
Lorentzian Shape

AbstractWe report on theoretical analysis of magneto-optically induced longitudinal perturbations in chirped magneto-optical Bragg gratings. The induced perturbations considered are of Lorentzian shape, with a spatial extent considerably larger than the spatial grating period but at least an order of magnitude less than the geometrical length of the grating. In the numerical simulation of the proposed device, we show on a high polarization state selectivity in the region of the perturbation, with resonance peaks of transmission for circularly polarized orthogonal components possessing a full width at half maximum as narrow as 0.18 nm, meanwhile being separated by 0.6 nm.

Transmission characteristics of Sagnac interferometers based on fiber Bragg gratings

2002 ◽  
Vol 19 (11) ◽  
pp. 2770 ◽  
Author(s):  
Xuewen Shu ◽  
Luzhi Yu ◽  
Donghui Zhao ◽  
Lin Zhang ◽  
Kate Sugden ◽  
...  
Keyword(s):  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Transmission Characteristics
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