光学系统中，为防止像差的引入造成成像质量下降，光学元件的准直与间距必须严格保证。所以，在光学仪器接口设计过程中，提高接口的重复性定位能力和降低接口的接触应力水平是非常重要的。在30 m 望远镜(TMT)三镜系统设计过程中，三镜作为Ritchey-Chirtien (R-C)式光学系统中重要的光学元件，需严格保证其位置和姿态。三镜系统寿命周期中，由于清洗、镀膜的要求，需要多次拆装，为保证装配精度，需设计了一套定位用运动学接口。从运动学定位原理出发，使用赫兹接触理论以及IBM 磨损理论对运动学接口进行了相应校核，并分析了影响运动学接口重复性定位精度的相应误差源，使用蒙特卡罗方法进行了相应仿真。另外，以三镜面形作为评指标，使用Ansys 软件模拟了运动学接口，研究了接口参数对于三镜面形的影响。分析结果显示，在现有的设计及精度下，接口的接触应力水平满足使用要求，三个方向的重复性定位精度以及支撑效果能够达到设计指标。

In order to avoid the introduction of aberrations which make the image quality degrade, both alignment and shift of the optical components are strictly guaranteed in the optical system. The kinematic interface has a wonderful performance in repeatability and low level of contact stress. So it is widely used in optical system. The thirty meter telescope (TMT) is an Ritchey-Chirtien (R-C) optical system. The tertiary mirror is employed to bend the light to the instruments. According to the requirement of the accuracy assembly this mirror is frequently removed to clean and recoat. So a kinematic interface is designed to meet the requirement. The study on the kinematic principle in positioning the rigid body is introduced. Then a preliminary design is constructed according with the mechanical principles. Thus the Hertz contact theory and IBM wear theory are employed to check the contact stress and the wear situation. At last, a positioning accuracy simulation is carried out by the Monte-Carlo method. In addition, a simulation is carried out to analyze the support performance in Ansys software. And some parameters is optimized. The results show that both the contact stress and the wear situation can meet the requirements. In addition, the repeatability in three directions and the support performance are achieved.