PROBLEM TO BE SOLVED: To allow a precise measurement of the flow rate of a fluid in a measurement target by a non-contact type laser Doppler method.SOLUTION: The present invention includes: means for forming a light converging part having a predetermined measurement volume in a measurement object by applying laser light to the measurement object means for receiving backscattered light from the light converging part means for conducting the frequency analysis of a signal which has received means for controlling the position of the light converging part in the depth direction on the basis of the intensity of a signal in a low frequency band from the result of the frequency analysis means for correcting the intensity of a signal in a high-frequency band in the result of the frequency analysis from the relation between the signal intensity in the low-frequency band and the position in the depth direction and means for calculating the flow rate on the basis of the corrected signal intensity in the high-frequency band and the frequency.SELECTED DRAWING: Figure 3COPYRIGHT: (C)2018,JPO&INPIT【課題】レーザドップラ法による非接触式で、精度よく測定対象内の流体の流量を測定できるようにする。【解決手段】測定対象にレーザ光を照射して、前記測定対象内に所定の測定体積となる光収束部分を形成する手段と、前記光収束部分からの後方散乱光を受光する手段と、前記受光した信号を周波数解析する手段と、前記周波数解析の結果から、低周波数帯の信号強度に基づいて前記光収束部分の深さ方向の位置を制御する手段と、前記低周波数帯の信号強度と前記深さ方向の位置の関係から、前記周波数解析の結果の高周波数帯の信号強度に補正を行う手段と、前記補正が行われた高周波数帯の信号強度および周波数に基づいて流量を計算する手段とを備える。【選択図】図3
