基于像散的光学元件厚度非接触测量研究

Non-contact thickness measurement of optical elements based on astigmatism

为了解决光学工厂低成本高精度检测光学元件厚度的实际问题,采用像散法厚度测量技术搭建了测量系统,并进行了理论分析和实验验证.该系统通过柱面镜引入像散形成长宽比与厚度相关的椭圆光斑,基于实时图像处理获得元件厚度,具有较高的测量效率,最后使用商用玻璃平片及平凹透镜进行了测量实验.结果表明,该系统测量不确定度在置信概率95%时小于2μm,中心厚测量范围为25mm,能够满足目前一般加工公差要求;该装置操作简单、精度高、成本低,可用于测量透明及不透明材料,适用范围较广.该装置为企业提供了一种低成本、非接触、高精度的厚度测量方案,适合中小型光学加工企业使用,具有广阔的应用前景.

In order to measure thickness of optical elements with low cost and high precision in optical factories, astigmatism thickness measurement technology was used to build the measurement system. Theoretical analysis and experimental verification were carried out. In this system, astigmatism was introduced into cylindrical mirror to form elliptical spot with thickness-dependent aspect ratio. The thickness of components was obtained based on real-time image processing with high measuring efficiency. Finally, measurement experiments were carried out with commercial glass plates and concave lenses. The results show that measurement uncertainty of the system is less than 2 μm when confidence probability is 95%. Measuring range of center thickness is 25mm and it can meet current general processing tolerance requirements. The device has the advantages of simple operation, high accuracy and low cost. It can be used to measure transparent and opaque materials with a wide range of application. The device provides a low-cost, non-contact and high-precision thickness measurement scheme for enterprises and is suitable for small and medium-sized optical processing enterprises. It has broad application prospects.