空间滤波测速系统中输出信号的基底成分，理论上可以通过差分方法完全消除。但由于由被测物体表面各处散射到光学系统并被探测器接收到的光能量不一致等原因，导致输出信号中仍然有基底成分残留，为信号特别是低频信号的探测带来困难。为了消除差分滤波器输出信号中残留的基底成分，对空间滤波测速仪中的图像传感器型差分滤波器的结构进行了优化设计。列出并分析了图像传感器型差分滤波器的各种可能结构形式，并且选择了几种典型的结构进行了实验。分别在均匀照明和非均匀照明条件下，从功率谱和信噪比两个方面分析了输出信号的质量，为滤波器结构的优化提供了依据。通过对比不同滤波器结构下系统输出信号的质量，得到了一种最为合适的能大大消除输出信号中残留的基底成分的滤波器结构。

The pedestal components in output signals of spatial filtering velocimeter can be completely eliminated by differential method theoretically. However, because of varying amount of radiation energy incident onto the photodetector, some pedestal components still occur in the output signals, making it difficult to pick up desired signals, especially signals having very low frequencies close to zero. To remove the pedestal components in output of differential filters, the configuration of a COMS-type differential spatial filter in spatial filtering velocimeter was optimized. Every possible configuration of a differential filter was listed, and several typical configurations were chosen to analyze in detail by carrying out experiments. The quality of the output signals were analyzed in the aspects of power spectrum and signal-to-noise ratio under the condition of uniformed and non-uniformed illumination respectively. By comparison of quality of output signal from these several typical spatial filters, a most suitable configuration was obtained. This optimized configuration can noticeably eliminate the pedestal components in output signals.