基于条纹反射的拼接镜面检测技术研究

To improve the resolution of the telescopes, the primary mirror is growing larger and larger in modern times. Due to the limitation of the single mirror's diameter, the primary mirror of the next generation telescopes goes to adopt large segmented mirror in common. Implementation of fine alignment (co-focus and co-phase) among segmented mirrors in the optical system is the guarantee of its imaging with high resolution. The misalignment error between individual segments includes the tilt, tip and piston. The measurement of misalignment error with high accuracy is a key technique for realizing the large segmented mirror. In the field of segmented mirrors measurement, there are still big gap at home and abroad. The fringe reflection technique (FRT) is widely used for specular mirror surface measurement with high accuracy nowadays. In this project, a new method for the segmented mirror measurement based on the principle of fringe reflection technique is proposed. To fulfill the co-focus and co-phase measurement, we will focus on the study of fringe illumination technology, system calibration and corrections, high precision phase shift technology, reliably phase unwrapping algorithm and misalignment error calculation algorithm of the adjacent segments position. Also, the experimental setup will be built to confirm the feasibility of this method. This method is simple, cheap and has large dynamic measurement rang. It has no special requirement for the environment and can work at all-day to improve the efficiency. This project can lay a foundation for the future large-scale segmented mirrors measurement of our country.

现代望远镜分辨能力的要求日趋提高，主镜口径在不断增大。受单块主镜望远镜的口径的限制，大口径拼接镜面是今后大型光学望远镜主镜的发展方向，而实现子镜间的有效拼接(共焦拼接与共相拼接)，是实现光学系统高分辨率的保证。子镜的拼接误差包括两个方向上的倾斜误差和垂直方向的位移误差，相应的检测技术是大口径拼接镜面制造的关键技术之一。在子镜拼接检测领域，我国与国外还存在着较大差距。本项目以传统条纹反射测量镜面三维面形的基本原理和方法为基础，研究基于条纹反射测量技术的子镜拼接检测新方法。本项目将重点研究条纹照明技术、系统标定及校准关键技术、高精度相移技术及可靠的相位展开技术、子镜误差评价算法等，以实现对拼接子镜的共焦及共相检测，并通过实验验证该方法的可行性。本项目系统结构简单、成本低、检测动态范围大、灵敏度高、无特殊环境要求、可全天候检测，提高检测效率。该项目可为我国未来大型拼接望远镜的检测奠定一定的基础。

研究基于结构光反射和摄像机标定的平面子镜拼接检测技术，为子镜拼接的共焦调试阶段，提供一种结构简单、效率高和精度恰当的全天候检测方法和技术手段。文章通过研究摄像机标定图样的特征点提取算法，得出了一种提取精度高、抗噪性和抗离焦性强的标定图样和特征点提取算法，然后提出了平面镜倾斜和位移的测量方法，引入虚像平面坐标系，将平面镜倾斜和位移测测量转变为标定点阵虚像平面的倾斜和位移的测量。并用一系列实验证明该方法的可行性，并使用在平面子镜实时测量拼接实验中。