提出一种用于低信噪比光腔衰荡时间准确提取的信号平滑方法，该方法基于数字图像处理领域的空间滤波平滑技术。首先推导了这种平滑方法的平滑过程和平滑效率，并与其他平滑算法进行了对比。推导结果表明基于均值滤波算子的空间滤波平滑方法具有最高的平滑效率。其次，分析了信号平滑方法的实用效果，结果发现该平滑方法与加权线性最小二乘算法相结合能够实现高精度、快速同时准确度较好的光腔衰荡时间提取。最后结合实验数据检验了平滑方法的处理效果，取得了列文伯格-马夸尔特算法相一致的衰荡时间提取结果。

In cavity ring-down technique, a signal smoothing method based on spatial filters which have been used in digital image processing is presented for accurate cavity decay time extraction of low signal-to-noise ratio decay signal. Its smoothing procedure was derived and its smoothing efficiency was compared with other smoothing methods. Derivation showed the mean value spatial filter had the highest smoothing efficiency. The application of decay signal smoothing was also analyzed. The combination of the mean value spatial filter with the weighted least square methods was recommended when processing low signal-to-noise ratio decay signals. This method was tested in experiment and achieved almost the same results with the Levenberg-Marquardt algorithm.