中文摘要：

研制光学天文望远镜拼接主镜时，需要精确检测各子镜单元之间的法向光程差。在对四棱锥波前检测原理分析的基础上，通过反射立方体模拟拼接镜面，开展四棱锥传感器的检测实验，验证了四棱锥传感器检测信号和拼接镜子单元间的piston误差信号之间存在确定的函数关系。在一个波长的位移行程内，目前可以达到数十纳米的测量精度。

英文摘要：

It is necessary to measure the piston error of sub-elements accurately when developing segmented mirror of optical telescope. On the basis of analyzing the pyramid sensor （PS） principle, some piston measurements were carried with sub-dements stimulated by two reflective cubes. A certain relationship is confirmed between the sensing value and the relative piston value of sub-elements. At present, the measuring accuracy is about several tens of nanometers when the relative displacement between two elements is within one wavelength.