| 摘要 |
<p>Fluid velocity measurement apparatus which utilises Doppler-shift spectral analysis includes a narrow line width light source (1), the light from which passes through a beam expander (3) to provide an irradiated region, for example a two-dimensional plane, in which velocity measurements may be taken. Light scattered from small particles in the irradiated region is collected in an imaging system (4) which enables spectral analysis of the scattered light for determining the velocity of the light scattering particles in the irradiated region. A single camera (13) is used in the imaging system (4) to obviate the need for costly electronics to synchronise images obtained. Also to improve the accuracy of measurement, selected parameters of the apparatus may be measured (2,5) to allow for perturbations in the velocity measurements obtained. <IMAGE></p> |
