一种非接触测量光学零件厚度的方法

Non-contact measurement method for thickness of optical element

为了实现光学零件厚度的非接触测量,设计了一种基于电光扫描的非接触测量方法。采用电扫描技术控制光开关,形成半径依次减小的环状光束,经过锥透镜后在光轴上形成连续移动的光点,当光点瞄准待测光学零件表面时,反射能量出现峰值,即定位了待测零件的表面,进而获得光学零件的几何厚度。建立了测量平板零件厚度和透镜中心厚度的数学模型;从理论上探讨了该方法的测量范围和测量精度。结果表明:设定锥面镜口径为100mm,材料折射率为1.52,当锥面镜的锥角从1°变化到40°时,测量动态范围可以从5507mm变化到26mm;当测量范围为26mm时,测量精度可以达到2.5μm。该方法可基本满足目前光学零件中心厚度的测量需求。

In order to realize non-contact central thickness measurement of the optical elements,an non-contact measurement system is established based on the electrical-optical scanning technology.Continuous moving light points are acquired in the optical axis when annular light produced by electrically controlling the optical switch array crosses the axicon.When the optical element places in the middle of these continuous moving light points,the thickness of the optical elements can be evaluated by monitoring the reflective light energy because the reflective light energy can present a peak when one of light points coincides with a surface of optical element.The mathematics model for testing the thickness of parallel plane plate and lens central thickness are built respectively.The measurement range and accuracy are analyzed in theory.The results show that the measurement range for parallel plate element varies from 5507 mm to 26 mm with the cone angle of axicon increasing from 1°to 40°,its materials refractive index is 1.52 and its radius is 100 mm,and the minimum measurement accuracy can reach to 2.5μm with measurement range of 26 mm.It can satisfy the non-contact measurement requirements of the central thickness of the optical elements.