扫描干涉场曝光系统中的干涉条纹周期是相位锁定系统的重要参数，为精确测量干涉条纹周期，根据扫描干涉场曝光系统的特点提出了分束棱镜移动测量干涉条纹周期的方法，根据高斯光束传播理论，分析了该方法的理论误差；提出了周期计数法对周期测量数据进行计算。为降低对系统二维工作台运行及稳定精度的要求，提出了小行程高精度位移台辅助测量周期的方法，并进行了相关实验验证。结果表明：小行程位移台辅助周期测量方法在原理上可行，对于干涉条纹线密度1800 line/mm 的系统参数，小行程位移台辅助周期测量的重复性可达到1.08×10-5(σ值)，曝光实验的实测值与理论模型之间一致性较好，验证了该周期测量方法的可行性。

Interference fringe period is a very important parameter of phase locking in scanning beam interference lithography system (SBIL). According to the feature of the SBIL system, a method that period is measured by moving beam-splitter is proposed. Based on Gaussian beam propagation theory, theoretical error is analyzed. Period counting method is proposed to calculate fringe period. In order to make it easy for two-dimension stage design, measuring period by short-stroke linear stage’s assistance is put forward and experiments are done. The results show that: the method that measuring period by short-stroke linear stage’s assistance is feasible in principle. When fringe density is 1800 line/mm in SBIL system, period measurement repeatability is 1.08 ×10-5 (1σ). Data measured in exposure experiments is consistent with the model, then the feasibility of this method is verified.