摘要
对不同速度下散斑在多普勒测速计中的影响进行了理论分析,并与实验结果进行了比较.结果发现多普勒频率的展宽与其中心频率的比值在32.2～379.6 mm·s-1的速度范围内约为30%,其中散斑是影响频率展宽的主要因素.因此速度测量中散斑所引起误差是难以忍受的,必须尽量消除散斑对测量的不利影响.采用锁相环可以消除这种不利的影响.
A theoretical analysis for speckle effect and comparisons with experimental results on laser Doppler velocimeters at different velocities are presented. It is found that the value of ratio between frequency broadening and center frequency is about 30% from 81.8 mm·s^-1 to 379.6 mm·s^-1 and that the effect of speckle pattern is one of the main reasons. The error caused by the effect of speckle pattern is an intolerant value in velocity measurements which need be eliminated. And this bad effect can be eliminated by employing the PLL method.
关键词
多普勒测速仪
散斑
干涉仪
Laser Doppler velocimeters
Speckle
Interferometers
