光学与光电技术, 2017, 15 (3): 16, 网络出版: 2017-07-10
一种消除后表面反射干扰的新型PMD面形检测技术
A Novel Phase Measuring Deflectometry for Eliminating Interference of Back Surface Reflection
相位测量偏折术 光学面形检测 后表面反射 多频条纹偏折术 谱估计 phase measuring deflectometry optical surface testing back surface reflection multi-frequency fringe deflectometry spectrum estimation
摘要
相位测量偏折术(PMD)是一种结合光线反射原理和条纹相位编码的光学面形检测方法,具有设备简单、成本低廉、稳定抗干扰等优点。但传统的偏折术需要对透明元件后表面进行黑化或粗糙化处理,以避免后表面反射对条纹相位提取的干扰,过程中可能损伤光学表面。分析了PMD面形检测方法用于透明元件检测的数学模型,提出了一种基于多频条纹反射和谱估计算法的新型PMD——多频条纹偏折术,分离了透明元件前后表面反射信号。从数字信号分析角度描述了谱估计方法分离精度的影响因素,并给出了分离结果优化的具体方案。进行了数值模拟和实验验证,取得了与基于相移的传统PMD非常接近的检测结果,证明了多频条纹偏折术的正确性和可行性。实验结果表明,该技术具有精度高、无需改变现有实验装置和待测元件的优点,为透明元件的无损静态检测提供了可靠的方法。
Abstract
Phase measuring deflectometry (PMD) is a kind of optical surface measuring method based on reflection principle and fringe phase encoding, which has the advantages of uncomplicated equipment, low cost, and strong anti-jamming capability etc. But the traditional deflectometry always blackens or roughens the back surface of transparent element, to avoid the interference of back surface reflection and to get accurate phase matching values, which will damage the optical surface. The accuracy mathematical model for intensity signal received by CCD in PMD is built. This paper presents a novel multi-frequency fringe deflectometry, using multi-frequency fringe projectionand spectral estimation, thus the reflection signals of the front and back surfaces are separated. The influence factors on the separation accuracy of the spectral estimation method are described from the view of the digital signal analysis, and the optimization scheme of the separation results is given. The measurement of multi-frequency fringe deflectometry is verified by numerical simulation and experiments, the measurement results are compared with the traditional PMD result based on phase shift. The experimental results show that the algorithm provides a practical approach for the measurement of optical components withhigh accuracy, without changing the existing experimental device and damaging the optical surfaces.
王琴, 李大海, 鄂可伟, 章涛, 金成英. 一种消除后表面反射干扰的新型PMD面形检测技术[J]. 光学与光电技术, 2017, 15(3): 16. WANG Qin, LI Da-hai, E Ke-wei, ZHANG Tao, JIN Cheng-ying. A Novel Phase Measuring Deflectometry for Eliminating Interference of Back Surface Reflection[J]. OPTICS & OPTOELECTRONIC TECHNOLOGY, 2017, 15(3): 16.