26 November 2001 In-line fiber optic laser Doppler velocimetry
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Abstract
In this paper, an all fibre compatible laser Doppler velocimeter featuring a fibre-optic filter device for frequency discrimination is presented for the first time. The technique is based on the fabrication of a Fabry-Perot filter using in-fibre Bragg gratings for measurement of the in-line velocity component. The choice, design and fabrication of the in-fibre filters are discussed. Problems that affect the stability of the system are addressed. These include the design and implementation of two-independent active feedback control loops for the argon-ion laser wavelength and phase of the fiber-optic filter. An optical fibre-linked probe head, constructed in-house, is used to couple the laser beam at 514.5 nm to and from the measurement volume. Fast photomultiplier tube detectors are used and signal capture and processing is performed on a digital storage oscilloscope (300 MHz) or on a PC. The system is successfully demonstrated by measuring the velocity of a rotating disc (10-cm diameter) over a velocity range of +/- 15 ms-1 with a resolution of 0.2 ms-1.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Edmon Chehura, Chen-Chun Ye, Ralph P. Tatam, "In-line fiber optic laser Doppler velocimetry", Proc. SPIE 4448, Optical Diagnostics for Fluids, Solids, and Combustion, (26 November 2001); doi: 10.1117/12.449363; https://doi.org/10.1117/12.449363
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