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1 November 2007 Modified fringe-counting technique applied to a dual-cavity fiber Fabry-Pérot vibrometer
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We report a relatively innovative method for automated fringe counting of a dual-cavity extrinsic fiber Fabry-Perot interferometer for vibration measurements based on the adaptation of the conventional zero-crossing technique to take into consideration two interdependent series of interference fringes. Two sets of interference signals generated by the fiber interferometric vibrometer are quadrature phase-shifted using phase retarding optics and exploited in the fringe counting process to generate the desired crossing-over signals. Each time period of the individual set of interference signal is subdivided into 16 crossing points via the modified fringe-counting method. A program written in MATLAB® is next developed for calculating the number of crossing points and plotting the displacement curve. This method has been found to be capable of automatically processing the two sets of interference fringes reliably. In addition, the program also calculates the displacement amplitudes of a vibrating target measured by the sensor to a resolution of λ/64. A reference displacement sensor has been used for comparison with output data from the interferometer, resulting in a percentage error of approximately 0.41% in the measured displacement.
©(2007) Society of Photo-Optical Instrumentation Engineers (SPIE)
Saroj Pullteap, Han-Cheng Seat, and Thierry M. Bosch "Modified fringe-counting technique applied to a dual-cavity fiber Fabry-Pérot vibrometer," Optical Engineering 46(11), 115603 (1 November 2007).
Published: 1 November 2007

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