采用立体视觉的子孔径拼接测量工件定位

为了实现大口径光学元件的子孔径拼接干涉测量，提出了采用立体视觉进行光学元件位姿测量的方法，建立了基于双目视觉的子孔径拼接测量系统，对该系统的数学模型、测量原理以及基于四元数法的位姿变换矩阵求取方法进行了研究。首先，介绍了圆形子孔径拼接干涉测量的原理，并基于齐次坐标变换分析了其对工件定位的要求，接着引入了立体视觉辅助测量系统，建立了其通用测量模型，利用双目视觉获取不同子孔径测量时与工件刚性连接的特征点的三维全局坐标，在完成全部子孔径测量后利用四元数法求取各子孔径相对于全局坐标系的转换矩阵，然后利用优化拼接算法将各子孔径数据统一到全局坐标系下，完成大口径光学元件的全局测量。最后利用该系统实现了对口径为150mm平面和100mm球面的检测。实验结果证明，在本系统中，立体视觉系统平移定位精度优于0.1mm，转动测量精度优于0.01度，能够给优化拼接算法提供一个有效的初始值，且该方法能够快速给出各子孔径间的相对坐标变换且在其视场范围内不产生误差累积，方法简单实用，稳定可靠。

Work-piece Localization Method in Sub-aperture Stitching Test Based on Stereovision

In order to realize sub-aperture stitching measurement of large-aperture optics, a work-piece localization method based on stereovision is introduced. A measurement system is established and its mathematical model, measuring principle and the obtain of the transformation matrix and etc is investigated. First, the measuring principle of the sub-aperture stitching test is introduced, and its requirement to the work-piece localization is analyzed. Then the stereovision measurement system is introduced, its measuring model is established. After that, the marked points’ 3D coordinates which are rigid connected with the optics under test are obtained and the transformation matrix can be solved out by quaternion method. Then, the full-aperture phase map can be synthesized by mathematically minimizing the mismatch among the overlapping areas of all sub-apertures. Finally, a 150mm flat and a 100mm convex sphere are tested using this method. Experimental results indicate that the precision of the system’s translation and rotation measurement are better than 0.1mm and 0.01degree, respectively. This can provide an effective initial value for the stitching algorithm and its measurement error does not cumulative along with the motion in its view field. It can satisfy the system’s precision requirements and it is non-contact, simple, and rapid speed, as well as strong anti-jamming and stabilization.