相位调制器是相干合成孔径望远镜中光束合成机构的关键部件,精确测量相位调制器的运动信息是相位调制器控制的核心技术之一。提出了基于平面法线向量的三自由度(俯仰角、方位角和轴向位移)测量方法,基于法线向量的变化解算角度和位移信息,并对所提方法进行详细描述,分析了影响测量精度的因素。实验结果表明:旋转角α和γ的转动范围分别为0~0.44 mrad和0~0.28 mrad,位移移动范围为0~3 μm;在测量范围内,角度误差小于3.3 μrad,位移误差小于50 nm。所提方法具有结构简单、测量精度高等优势,可广泛应用于相位调制器等的三自由度测量中。

The phase modulator is a key component of the beam synthesis unit in the coherent synthetic aperture telescope, and the accurate measurement of the motion information of the phase modulator is one of the key technologies for phase modulator control. The three-degree-of-freedom (pitch, azimuth, and piston displacement) measurement method based on the plane normal vector is proposed. The angle and displacement information are solved according to the change of the normal vector. The proposed method is described in detail and all the factors influencing measurement accuracy are analyzed. The experimental results show that the displacement range is 0-3 μm when the rotation ranges of the rotation angles α and γ are 0-0.44 mrad and 0-0.28 mrad, respectively. Within the measurement range, the angle error is less than 3.3 μrad and the displacement error is less than 50 nm. The proposed method has the advantages of simple structure, high measurement accuracy, and so on, which can be widely applied in the three-degree-of-freedom measurement of phase modulators and others.