METHOD AND APPARATUS FOR MEASURING FLOW VELOCITY DISTRIBUTION AND FLOW RATE BY LASER DOPPLER METHOD

摘要

PURPOSE:To enable three-dimensional distributions of the velocities of flow to be measured by expanding a laser beam to create a thin and broad laser beam, entering the same to the measuring target and leading the interference light on the image plane thereof to photo detectors by using multiple optical fibers. CONSTITUTION:As incident light to a fluid field, a laser beam is used by stopping the same to linear form by a spherical lens SL of a long focus or stopping to a broad and thin beam by a cylindrical lens CL in order to improve space resolution and obtain strong scattering light. Of the scattered light having been subjected to Doppler shift by the scattering particles contained in the fluid, two angle components are drawn out with the mask M on the focus of a projecting lens Pr and are let to interfere on the image plane, on which a plurality of photo detectors D are placed and the light is led into these detectors D through a number of optical fibers F, whereby the beat signals are measured.