高精度轴对称非球面反射镜轮廓测量方法(特邀)

High-precision profile measurement method for axisymmetric aspheric mirror (invited)

  • 摘要: 为实现轴对称非球面反射镜轮廓的高精度、可溯源测量,建立了非球面测量轨迹的数学模型,提出了一种基于独立计量回路的非接触式坐标扫描测量方法。该方法采用分离式计量框架结构,有效减少了跟踪扫描模块运动对测量精度的影响;测头采用集成阵列式波片的四象限干涉测量系统,保证测头精度的同时更有利于实现复杂面形轮廓的跟踪扫描运动;设计扫描执行机构与多路激光干涉系统共基准的运动模块,实时跟踪扫描运动机构的位置信息,提高测头空间定位精度并使其测量值能溯源到“米”定义。搭建测量装置测试该方法的准确测量精度,试验结果表明,测量误差小于0.2 μm,重复性精度为70 nm,测量精度达到亚微米级。

     

    Abstract: In order to achieve the goal of high-precision and traceable aspheric surface profile measurement, a mathematical model of the measurement trajectory is established for the surface profile measurement of axisymmetric aspheric mirrors, and a non-contact coordinate scanning measurement method with independent metrology loop is proposed. The method applies a separated metrology frame, which effectively reduces the influence of each motion module on the measurement accuracy of the system during the measurement process; the probe adopts a four-quadrant interferometry system with integrated array waveplates, which improves the dynamic performance of the probe and is more conducive to the measurement of complex aspheric surface shapes; the motion module with a common reference between the scanning actuator and the multiplexed laser interferometry system is designed to track the position information of the scanning motion mechanism in real time, which improves the accuracy of the scanning motion and enables the measurement of the surface shape. The scanning actuator is designed to track the position information of the scanning motion mechanism in real time to improve the accuracy of the probe motion and make its measurement value traceable to the definition of "meter". The measurement device is built and the surface profile of the standard sphere and aspheric mirror are measured separately. The test results show that the measurement error is less than 0.2 μm and the repeatability accuracy was 70 nm, and the system measurement accuracy reaches submicron level.

     

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