Fabry-Perot sensors

Claus, R. O. Gunther, M. F. Wang, A. Murphy, K. A., Extrinsic Fabry Perot sensor for strain and crack opening displacement measurements for 200 to 900° C, J. Smart Mater. Struct 1992, 1, 237 242... 

Specialty Fabry-Perot sensors, long-period gratings 9 V Power supply 90 min battery operation... 

Scheme 10.5 Principles of various sensing methods based on light interference or diffraction (a and b) PCCA sensors (c and d) Fabry-Perot sensors (e) holographic sensor (f) inverse opal sensor (g) diffraction grating sensor.

Koo K P, LeBlanc M, Tsai T E et al., Fiber-chirped grating Fabry-Perot sensor with multiple-wavelength-addressablefree-spectral ranges , IEEE Photon. Technol. Lett, 1998, 10(7), 1006-8. 

Hong C S, Kim C G, Kwon I and Park J W, Simultaneous strain and failure sensing of composite beam using an embedded fibre optic extrinsic Fabry-Perot sensor . Smart Structures and Materials 1996, SPIE, 1996, 2718, 122-33. 

Liu, T. Fernando, G. R, A Frequency Division Multiplexed Low-Finesse Fiber Optic Fabry-Perot Sensor System for Strain and Displacement Measurements , Rev. Sci. Instrum. 2000, 71, 1275-1278. 

Figure 13.55 shows the principle of a gas sensor based on an electrically tunable micromachined Fabry-Perot interferometer, and the shifting ol the pass band controlled by rhe tuning voltage. 

Mitchell G.L., A review of fabry-perot Interferometric sensors, in Optical Fiber Sensors, Proc.6th Int.Conf. OFS 89 (1989), H.J.Arditty, J.P.Dakin, R.ThKersten eds., Springer-Verlag, pp. 450-478. 

Although theoretically very attractive there are no reports on 10 sensors of the Fabry-Perot type. One may assume that this mainly originates from its technological complexity. 

Xiao, G. Z. Adnet, A. Zhang, Z. Sun, F. G. Grover, C. P., Monitoring changes in the refractive index of gases by means of a fiber optic Fabry Perot interferometer sensor, Sens. Actuators A Phys. 2005, 118, 177 182... 

Ran, Z. L. Rao, Y. J. Liu, W. J. Liao, X. Chiang, K. S., Laser micromachined Fabry Perot optical fiber tip sensor for high resolution temperature independent measurement of refractive index, Opt. Express 2008, 16, 2252 2263... 

Liu, N. Hui, J. Sun, C. Dong, J. Zhang, L. Xiao, H., Nanoporous zeolite thin film based fiber intrinsic Fabry Perot interferometric sensor for detection of dissolved organics in water, Sensors 2006, 6, 835 847... 

Cox, E. R. Jones, B. E. Fiber optic color sensors based on Fabry Perot interferometry, In First International Conference on Optical Fiber Sensors, London, 1993... 

In conclusion, it has been demonstrated that the manufacture of waveguides, Bragg reflectors, Fabry-Perot filters and anti-reflective coatings can be based on PS thin films. Such filters are applied for example in gas sensors, as described in the preceding section. 

The fiber optic sensors utilize an extrinsic Fabry-Perot interferometer to spectrally modulate light in proportion to pressure, temperature, or refractive index variations. Because they are based on spectral modulation instead of amplitude modulation, they are not affected by such common problems as fiber bending, connector losses, and aging. 

A device based on a porous silica substrate used as a Fabry-Perot interferometer has been reported as a sensor for organophosphorus nerve agents. The porous silica is coated with a surfactant and a copper hydrolysis catalyst. The mode of operation... 

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. 

Due to their high sensitivity to strain, temperature variation, vibration, and acoustic waves, embedded extrinsic Fabry-Perot interferometric optical fiber sensors have been developed to detect delamination, based on changes in the acoustic properties of the materials before and after delamination [41]. Impact events and corrosion cracking generate ultrasonic waves, which can be characterized using elliptical core fiber sensors [40]. The in-line Fabry-Perot interferometer seems well suited for the local detection of shear waves and the characterization of impact-induced damage. 

Figure 16.23 (a) Quasi-static strain measured with the tunable Fabry—Perot filter (TFPF)-demodulated FBG sensor signal (b) strain wave signals measured with the Mach-Zehnder interferometer (MZI)-demodulated FBG sensor compared with that measured by the PZT sensor [47]. 

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