LAMOST焦面板光纤定位精度检测系统的实现及关键技术研究

The large sky area Multi-object Fiber Spectroscopic Telescope (LAMOST) is an innovative reflecting schmidt telescope, promising a very high spectrum acquiring rate of several ten-thousands of spectra per night. By using the parallel controllable fiber positioning technique, LAMOST makes reconfiguration of fibers accurately according to the positions of objects in minutes and fine adjusting the fibers.During telescope observation period, each optical fiber unit positional accuracy directly determines the quality of subsequent spectrum acqusition,yet for real-time optical fiber positional accuracy,there only exists an internal information feedback which focus on the corresponding stepper motor driving conditions.However,this available information is not comprehensive,it can not offer the actual positionoal information for each fiber unit.Considering the LAMOST on-site environment,a novel real-time optical fiber positional accuracy detection system which can be integrated in the existing observation and control system will be developed in this project to solve this problem.During the observation interval,this system can offer a comprehensive and effective information feedback about the focal optical fiber postional accuracy.Based on this feedback,the observation assistants can properly adjust the observation strategies to ensure the effectiveness and accuracy of acquried spectrum.Furththermore,this fiber positional accuracy feedback can provide prior spectral quality information to the spectral processing personnel and optimal the spectrum processing efficiency.

大天区面积多目标光纤光谱望远镜（简称LAMOST）是目前国际上口径最大、视场最宽、光谱获取率最高的大型施密特望远镜，通过借助并行可控式双回转光纤定位系统，其焦面系统上的4000根光纤可以在数分钟内按预定天体坐标快速精确地对准各自观测目标并进行精调。望远镜观测时每一光纤单元定位情况的好坏直接决定相应天体目标的光谱质量，然而目前针对观测时光纤定位精度情况仅有的信息就是定位时光纤步进电机驱动情况的反馈，是一个内部信息，并不全面，无法给出每一个光纤单元的实际定位精度情况。在本项目中，结合LAMOST现场环境，将会研制出一套可集成于LAMOST观测控制系统的光纤单元定位精度实时检测系统。在望远镜观测间隙,通过此系统能够第一时间获取全面有效的光纤定位精度信息反馈，由此决定进一步观测处理措施以保证观测光谱的有效性和准确率。同时此反馈也会为光谱分析人员提供光谱质量相关的先验信息，优化光谱处理效率。

大天区面积多目标光纤光谱望远镜（简称LAMOST）是目前国际上口径最大、视场最宽、光谱获取率最高的大型施密特望远镜，通过借助并行可控式双回转光纤定位系统，其焦面系统上的4000根光纤可以在数分钟内按预定天体坐标快速精确地对准各自观测目标并进行精调。望远镜观测时每一光纤单元定位情况的好坏直接决定相应天体目标的光谱质量，本项目就是结合LAMOST现场环境，研制一套LAMOST光纤单元定位精度实时检测系统，确定望远镜观测时的光纤定位精度。在项目具体实施过程中，采用现场搭建的图像采集设备获取走位后的焦面板光纤单元图像，挖掘图像特点，结合已知信息，检测出定位错误的光纤单元，主要采用的算法有光重心法、最小二乘拟合、多项式拟合。目前已经基本完成图像采集器和光源设备的现场搭建，关键算法的实现，检测程序界面的设计。在这些基础上，目前已完成多次实验数据的采集，及相应的检测处理和分析。通过多次现场实验方案的改进及算法优化，检测系统的重复检测精度约为0.5个角秒，虽仍有待于进一步的提高，但是已基本可以用于光纤单元的定位精度检测。