针对金属带材等非透明样品厚度的高精度原位测量问题，本文基于光谱干涉绝对距离测量的基本原理，提出了一种结构紧凑、全光纤的非透明样品厚度非接触式差分测量方法. 首先介绍了光谱干涉的基本原理及绝对距离测量的具体实现，然后设计、搭建了一套全光纤差分光谱干涉测量非透明样品厚度的原理验证光路，并开展了原理验证实验，实现了标准量块厚度的高精度测量，最后对该方法的测量误差进行了分析，分析结果表明，采用该方法可以达到亚微米级的厚度测量精度.

In order to in-situ acquire the thickness of non-transparent samples, such as metal strip, with high precision, a compact thickness measurement method of non-transparent samples with all fiber based on differential spectral interference has been proposed. Firstly, the basic principle of spectral interference and the specific implementation of absolute distance measurement are introduced. Then, a set of optical fiber differential spectral interference for non transparent sample thickness measurement is designed and built, and the principle verification experiment is carried out to realize the high-precision thickness measurement of standard gauge block. Finally, the measurement error of this method is analyzed, and the results show that the accuracy of this method can reach the sub micron level.