以相移干涉测长为应用背景，提出了一种基于“机械扫描”的相移测长方法。利用超高弹性石英材料研制出了干涉测长所需的单体3路相移装置，并利用该相移装置建成了相移测长装置，成功地将位移传感器的量值在线溯源到光学频率标准，从而实现了对3路相移的准确测量。介绍了一种引入步长控制误差的“新五幅相移”实现相位解算方法，算法准确度达到0.01%。对不确定度的定量分析结果表明，基于该机械扫描式相移技术构建的绝对长度测量系统准确度可达0.5 nm。

Based on the application background of length measurement, a novel phase-shifting interferometry is presented. A precise phase-shifting device for length measurement by pressure variation is developed. This device based on single-quartz component is made to carry out the generation of triple phase-shifting, and an essential technique to make online calibration of the capacitor sensor is also realized. The original phase is solved by the developed five-interferogram algorithm with the uncertainty of 0.01% phase periods. The experimental results show that the phase-shifting obtained by this device is up to 1 μm and the variation for length measurement is 0.5 nm.