研究一种采用频移分离方法的新型三维激光多普勒测速仪(3DLDV).该仪器以单色He-Ne激光器和单只光电探测器并配合简单的光学发射和接收系统即实现了三维速度分量的同时测量.三个分量的速度信号由声光调制器引入的三种光学颁移区分，通过电子滤波器完成信号的相互分离.在光学发射系统设计中采用独特的单轴四光束结构，通过光束组合形成三组双光束差动模式的激光多普勒测速仪光路.本文中还给出了该仪器的系统设计参数并分析了轴向分量的测量精度.

A new three-dimensional laser Doppler velocimeter (3D LDV) by only using frequency shift separation method has been developed. Simultaneous measurementS of three velocity components are realized by a single color He-Ne laser and one photodetector with simple transmitting and receiving optics. The signals corresPOnding to different velocity components are distinguished by three different optical frequency shifts introduced by three Bragg cells, and separated by band-pass filters. A novel and simple four-beam transmitting optics which contains three sets of dual-beam LDV systems is proposed, and the design specification of the 3D LDV system is presetned. The measuring accuracy of the on-axis component is also discussed in this paper.