Multicomponent time-division-multiplexed optical fibre laser Doppler anemometry

A multicomponent time-division-multiplexed laser Doppler anemometer is described which uses a single high-frequency pulsed laser diode as a source. Time-division multiplexing requires a single detector channel, removing the need for multiple detectors and wavelength separation optics found in conventional CW laser Doppler systems. Using optical fibres to distribute the pulses into each channel and impose a delay between channels reduces the electronic requirements of such an instrument. The suitability of the laser diode and optical fibres is assessed and the signal processing needs discussed. Results for a bench-top and a fibre-linked two-dimensional probe system are presented, showing measurements on a rotating disc and a water-seeded air jet