采用三稳频激光源实现绝对长度测量

合成波长法利用多个波长构建数值足够大的合成波长,从而可实现绝对测量.然而实际应用中要找到波长值合适且波长稳定性足够高的多个波长难度很大.本文研究了一种长度绝对测量光路,采用三个高精度稳频波长构建合成波长链,建立合成波长链测量公式及其级间过渡条件,搭建相移干涉光路测量各单一波长的干涉级次小数值,最后实现绝对长度的高精度测量.对零膨胀微晶玻璃样品进行了长度测量实验,实验结果及误差分析表明长度测量不确定度约为3 nm.所提方法对样品的初测精度要求较低,而测量范围仅受干涉光路的长度限制. 

Absolute Length Measurement Based on Three Frequency-Stabilized Lasers

To measure absolute length, the synthetic wavelength methods must construct a long enough synthetic wavelength made use of several single wavelengths, and make integer of the interference order be zero or a deterministic value. However, it is not easy to find corresponding wavelengths with appropriate values and high wavelength stability in practice. In this paper, a synthetic wavelength absolute measurement method was presented, adopting three high frequency stability lasers to form the synthetic wavelength chain. The measurement equations as well as the transition conditions between grades were derived. And a corresponding phase shift interference optical path was built to make high precision measurement for the absolute length value of the sample. The experiment and error analysis results show the measurement uncertainty is about 3 nm (at 0.3 m sample). In this method the requirement for initial measurement accuracy of the length is low and the measurement range is only limited by the length of the interferometric optical path.