A novel processing scheme for a fibre optical low coherence laser Doppler anemometer system (for blood flow measurement)

A system has been assembled for measuring the Doppler frequency shift of scattered light in order to determine velocity. The signal recovery scheme utilises a novel adaptation of a Michelson interferometer to give two output signals in quadrature. Simple signal processing of the output signals then allows determination of velocity rather than speed, in a system which uses simple inexpensive optical components. The system also utilises a low coherence light source. This suppresses unwanted signals and allows the measurement region to be projected ahead of the fibre probe. The instrument is currently being tested in the measurement of fluid flow velocities.<
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