镜面拼接是一种提高望远镜分辨率的有效方法,拼接子镜间的相位平移误差是影响拼接望远镜成像质量的重要因素.针对当前拼接望远镜中的共相问题,提出了色散干涉图像峰值比值为评价函数的共相零位标定方法.以两个子镜为研究对象,对该共相零位标定方法进行了仿真验证,并搭建了两孔径共相零位标定实验平台,验证了基于色散干涉图像的拼接望远镜共相零位标定方法的可行性.实验结果表明,该方法不受2亿模糊性问题影响,可在几百微米共相误差范围内以10nm左右精度对共相零位进行标定,解决了现有标定方法动态范围受限的问题.
Astronomical telescopes with increasingly large apertures are required to upgrade the limit of diffraction and collect the light efficiently for the purpose of observing fainter and more remote objects with higher angular resolution. However, it is universally believed that traditional techniques of manufacturing, polishing and measuring large glass mirrors will soon face some practical challenges. Therefore, 10-m class or larger ground-based telescopes will need to employ arrays of several smaller segments to assemble into a large primary mirror. For a telescope with segmented mirrors, the piston errors between segments must be adjusted to nearly zero according to the requirements in order to be integrated into a single optical surface, which is known as co-phasing. One of the current co-phasing techniques, which has been successfully applied to Keck telescopes, employs an integration of edge sensors to detect the mirror shapes in real time with an optical phasing sensor to offer zero references for these sensors regularly. Another technique is demonstrated by use of a pyramid wavefront sensor (PWFS) to align and co-phase segmented mirrors in an active control close-loop with a single measurement. The co-phased "best fiat" positions of segments are used as the zero references in order to measure the interaction matrix between the PWFS and the segmented mirrors. So it must be addressed that how the zero co-phasing reference is calibrated with high precision in a large capture range on the issues of co-phasing segmented mirrors. The current methods either lack accuracies, or just measure piston errors correctly in a small range. In order to solve the problem, a zero co-phasing reference calibration method based on dispersed interferogram is proposed. Specifically, the idea of the method is to define an appropriate cost function which is used to evaluate the piston errors between segments. Then it will be easy to determine the zero co-phasing reference position while all the cost function values are calcula