基于时间差法的共焦测头测量的位移量是测头输出的光电信号中相邻驼峰之间对应时间差的一一映射。为了更加准确稳定地计算出光电信号中的时间差，本文分析了改进后测头输出光电信号的特点，指出了目前信号处理方法的缺陷，进而提出了相似形态分析法，用于计算相邻驼峰之间对应的时间间隔。实验数据显示，在采样频率为2 MHz的数据采集系统中，使用相似形态分析法计算得到的时间间隔的标准差为0.33 μs，高于最大值法的3.37 μs。结果表明，相似形态分析法计算结果准确，不受噪声的影响，对信号的前期处理要求低，易于实现，计算结果稳定且不受激光光强变动的影响和环境光的干扰。

The displacement measured by a confocal probe based on time difference method is an one-to-one mapping to the time difference between the two peaks in a photo-electric signal. In order to calculate the time difference accurately, the characteristics of photo-electric signal output from an improved probe was analyzed and then the defects in the current signal processing method were pointed out.A processing method named similar pattern analysis was persented to calculate the time interval between the two peaks. Experimental data show that in the data acquisition system with sampling frequency of 2 MHz, the standard deviation of time difference by using the similar pattern analysis is 0.33 μs,which is better than 3.37 μs by using the maximum value method. With the similar pattern analysis, it is easy to implement the signal pre-processing. The calculated results are accurate and stable and are not influenced by the changes of laser intensity and ambient light interference.