提出一种基于波数分辨的低相干干涉台阶高度测量系统。由宽带光源发出的光通过光纤迈克耳孙干涉仪获取被测量信息，色散光栅将宽谱干涉光束色散成波长在空间连续分布的光片，由线阵CCD 探测。将线阵CCD 的各个像元探测到的各个波长干涉信号转换成对应的波数干涉信号。对于波数干涉信号，相邻两个干涉信号峰值之间的波数变化量与干涉仪光程差的绝对值呈正比。因此，利用此测量系统可实现对台阶高度等物理量的绝对测量。利用缩短测量系统中光纤迈克耳孙干涉仪的两个干涉臂的长度减小环境干扰对测量系统的影响，获得高测量精度。本测量系统的测量分辨率为6.03 nm。对一个高度为50 μm 的台阶重复10次测量，测量结果的标准差为6.8 nm。

A high precision step height measurement system, which is based on wavenumber resolved low coherence interferometry, is presented. The information of the measurand is obtained with a fiber Michelson interferometer which is sourced by a broadband light source. The broadband spectrum interferometric beam is dispersed with a bulk dispersing grating to be an optical plate in which the wavelengths are continuously distributed. The optical plate is detected with a linear array charge coupled device (CCD). By transforming the wavelength spectrum of the interferometric signal into wavenumber spectrum, absolute optical path difference of the interferometer can be measured precisely by measuring the wavenumber difference between two neighboring peaks of the wavenumber spectrum. By shorting the length of the interferometric arms in the optical fiber Michelson interferometer, the environmental disturbances are depressed and high measurement precision is obtained. The measurement resolution is as high as 6.03 nm. A step height with the calibrated value of 50 μm that is configurated with two gauge blocks is measured by the system. The standard deviation of 10 times measurement results is 6.8 nm.