激光共焦透镜曲率半径测量系统

基于共焦技术独特的轴向层析定焦能力并结合气浮导轨平移台和激光干涉仪测长系统,研制了一套高精度、非接触激光共焦透镜曲率半径测量系统。该系统利用共焦轴向光强响应曲线的峰值点对应系统物镜聚焦焦点这一特性,使用峰值点对被测透镜的猫眼位置及共焦位置进行精确定位,并结合激光干涉仪获得透镜猫眼位置及共焦位置坐标值,从而计算得到透镜的曲率半径。系统由主控软件控制气浮导轨带动被测透镜在猫眼位置及共焦位置附近进行扫描测量,并实现信号采集和数据处理。实验表明,利用该系统测量透镜的曲率半径时,测量重复性优于2 μm,满足国内高精度透镜曲率半径测量的精度需求。该系统测量速度快、操作简便、结构简单且易于实现小型化。

Laser confocal measurement system for curvature radii of lenses

Combined an air bearing platform and a laser interferometer, a set of non-contact and high precision system for curvature radius measurements of lenses is developed based on the axial focusing of confocal technique. The developed system is characterized by that the peak point of the confocal axial intensive curve corresponds to the focus of an objective. On the characteristic, it identifies precisely the cat-eye and confocal positions of the test lens. Then it takes the laser interferometer to obtain the position coordinates of the cat-eye and confocal positions and calculates the curvature radius of the lens. Furthermore, the main control software drives an air bearing slider with a test lens to achieve the scanning measurement near the cat eye and confocal positions, and then acquires signals and processes data. Experimental results show that the measurement system has the reproducibility less than 2 μm, which meets the requirements of curvature radius measurement for high precision. The developed measurement system has the advantages of high test speed, easy operation, simple structure and easy to be miniaturized.