| 摘要 |
PURPOSE:To make it possible to measure a flow speed in the vicinity of a boundary surface or in a minute space by miniaturizing and micronizing the titled probe, by measuring the flow speed of a fluid at a flow speed measuring point by Doppler effect acting on mutual spaces of three laser beams. CONSTITUTION:The leading end of an optical fiber 3 connected to a laser beam source 1 through a lens system is inserted into an LDV micro-probe 4 as a constitutional element and, after three laser beams emitted from the LDV probe 4 are condensed to a measuring point P in a fluid 5, beam components incident to a beam receiving optical fibers 6a, 6b respectively arranged in the straight advance direction of each reference laser beam are guided to photoelectric multiplier tubes 7a, 7b along with beat components generated on the basis of Doppler effect affected on the flow speed of the fluid 5 by mutual interference of reference beam and scattered light. In this case, only respective beat components are extracted by band pass filters 8a, 8b while a voltage signal proportional to the beat frequency possessed by each beat component is further taken out by frequency-voltage converters 9a, 9b and desired data treatment is applied by an operator 17 to calculate the flow speed of the fluid. |
