为了将激光多普勒测速技术应用于野外流体速度测量,设计了一种基于舣光束模式的激光多普勒测速光学系统,采用光纤耦合半导体激光器作为光源,通过保偏光纤耦合器、保偏光纤准直器以及非球面透镜来实现激光的分束、准直与聚焦,形成干涉条纹,并利用接收透镜、针孔光阑以及雪崩光电二极竹检测多普勒信号光.结果表明,所设汁的光学系统的空间分辨率为0.046mm3,理论测量误差小于0.59%.系统体积小、装配方便、易携带,适合于野外流体速度测量.%An optical system of a laser Doppler velocimeter based on dual-beam mode was designed for flow velocity measurement in field, and error analysis was discussed with experimental results performed. In order to create interference fringe, the beam of a fiber-coupled laser diode was split by a polarization maintaining fiber coupler, then both the beams behind the fiber coupler were collimated by fiber collimator and focused by an aspheric lens. In order to detect Doppler signal, a colleeting lens and pinhole was used to project the useful scattering light onto an avalanche photo diode. Resolution of the built optical system was 0. 046mm3, and measurement error was less than 0. 59％ in theory. Because of its advantages such as small size, integration and convenience, the system is suitable for field measurement.
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