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Proceedings Paper

In-line fiber optic laser Doppler velocimetry
Author(s): Edmon Chehura; Chen-Chun Ye; Ralph P. Tatam
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Paper 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.

Paper Details

Date Published: 26 November 2001
PDF: 12 pages
Proc. SPIE 4448, Optical Diagnostics for Fluids, Solids, and Combustion, (26 November 2001); doi: 10.1117/12.449363
Show Author Affiliations
Edmon Chehura, Cranfield Univ. (United Kingdom)
Chen-Chun Ye, Cranfield Univ. (United Kingdom)
Ralph P. Tatam, Cranfield Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 4448:
Optical Diagnostics for Fluids, Solids, and Combustion
Carolyn R. Mercer; Soyoung Stephen Cha; Gongxin Shen, Editor(s)

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