LASER DOPPLER FLOW RATE MEASURING METHOD AND APPARATUS

PROBLEM TO BE SOLVED: To provide a laser Doppler flow rate measuring method and an apparatus which can perform efficient measurement in a two-dimensionally wide range by a simple optical system and an apparatus using a laser Doppler system.SOLUTION: The laser Doppler flow rate measuring apparatus comprises: a beam division element 14 for dividing a laser beam L from a laser source 12; sheet light formation optical systems 21, 22, 23, 24 for converting divided laser beams L1, L2 into planar thin sheet light Ls1, Ls2; and a condensing optical system 18 for making each of the divided sheet light Ls1, Ls2 to intersect with each other on the same plane so that the planes of two the sheet light overlap with each other. The laser Doppler flow rate measuring apparatus also comprises: an imaging optical system 26 for two-dimensionally imaging scattered light generated by particles p in fluid in an intersection area D where the sheet light Ls1, Ls2 intersects with each other; a light receiving element 32 on an imaging position of the imaging optical system 26; photoelectric conversion elements 40 for converting scattered light entering the light receiving element 32 into an electric signal; and calculation means 48 for calculating, for each photoelectric conversion element 40, a flow rate of the fluid in the intersection area D where the laser beam L is Doppler frequency-shifted. 【課題】レーザドップラー方式による簡単な光学系及び装置により、２次元的に広い範囲を効率的に測定可能なレーザドップラー流速測定方法及び装置を提供する。【解決手段】レーザ光源１２からのレーザ光Ｌを分岐するビーム分割素子１４と、分岐されたレーザ光Ｌ１，Ｌ２を面状の薄いシート光Ｌｓ１，Ｌｓ２にするシート光形成光学系２１，２２，２３，２４を有する。分岐した各シート光Ｌｓ１，Ｌｓ２を、その面同士が重なるように同一面上で互いに交差させる集光光学系１８を備える。シート光Ｌｓ１，Ｌｓ２が交差した交差領域Ｄでの流体内の粒子ｐによる散乱光を、２次元的に結像させる結像光学系２６を備える。結像光学系２６の結像位置にある受光素子３２と、受光素子３２に入射した散乱光を電気信号に変換する光電変換素子４０を有する。レーザ光Ｌがドップラー周波数シフトした交差領域Ｄでの流体の流速を、光電変換素子４０毎に演算する演算手段４８を備える。【選択図】図１