后向散射光特性与多普勒信号的质量密切相关。为了设计高性能的激光多普勒测速仪，运用散斑理论详细分析了激光多普勒信号的强度与散射光斑大小的关系，结合泛函理论给出了计算多普勒电流的散斑表达式，并通过实验的方法研究了回波信号的偏振特性及其强度分布。理论分析与实验结果表明，激光多普勒信号的强度与接收器件光敏面的直径成正比，与光斑的直径成反比；选用光斑较小的圆偏振激光束，并用光敏面尺寸较小的探测器在镜面反射方向上接收信号光，可以大大提高多普勒信号的信噪比，增强系统的探测能力，为提高系统的测量精度创造有利的条件。

In order to design a high performance laser Doppler velocimeter (LDV), the relationship between the signal intensity of laser Doppler and the diameter of spot was analyzed using the speckle theory, and the calculation formulas of the Doppler current was given based on functional theory. The polarization characteristic of scattered light and its intensity distribution were investigated. The results of theory and experiment show signal intensity of laser Doppler is proportional to the diameter of the active area in detector, and inverse proportional to the diameter of laser spot. By selecting circular polarization laser beam with smaller spot size and using detector of small active area to signal in specular direction, the signal to noise ratio and the detection capability of the system are improved significantly.