广角望远镜实时自动调焦的清晰度评价方法

发布时间：2018-03-18 12:17

本文选题：图像清晰度　切入点：自动调焦　出处：《光学精密工程》2017年05期 　论文类型：期刊论文

【摘要】：SVOM天文卫星附属的地基广角相机阵(GWAC)含有36个广角望远镜,其短时标的高精度自动观测建立在实时自动调焦的基础上,本文将对广角望远镜实时自动调焦的图像清晰度评价方法进行研究和实现。文章首先比较研究了常用望远镜图像清晰度评价方法的原理及在GWAC系统上的适用性,得出基于星像能量集中度的两种方法:星像50%能量半径、PSF的FWHM值适用于GWAC系统。区别于常用天文软件包IRAF费时的算法,本文提出了基于点源强度分布进行PSF拟合计算FWHM的方法,并进一步探究了诸如拟合模型、选星标准、定心精度、拟合半径、插值方法、插值间隔、FWHM后处理等关键方法参数对FWHM计算精度与速度的影响。最终得到一套适用于GWAC实时自动调焦的清晰度评价方法,并用C++编程实现。本文中方法 FWHM计算误差为0.046pixel,精度与IRAF相当,计算焦点位置一致;单图(挑选后约300颗星)计算时间为0.67s,约为IRAF计算时间的1/20,满足GWAC系统自动调焦的精度与实时性需求。研究结果在GWAC系统中得到应用,并可为其他自动化望远镜观测系统提供参考。
[Abstract]:The ground-based wide-angle camera array attached to SVOM astronomical satellite contains 36 wide-angle telescopes, and its short-time high-precision automatic observation is based on real-time auto-focusing. In this paper, the image sharpness evaluation method of wide-angle telescope real-time auto-focusing is studied and realized. Firstly, the principle of image sharpness evaluation method and its applicability in GWAC system are compared and studied in this paper. Two methods based on star image energy concentration degree are obtained: the FWHM value of star image 50% energy radius is suitable for GWAC system. Different from the time-consuming algorithm of IRAF, a method of calculating FWHM by PSF fitting based on point source intensity distribution is proposed in this paper. And further explored such as fitting model, star selection criteria, centring accuracy, fitting radius, interpolation methods, The influence of key parameters such as interpolation interval and FWHM post-processing on the accuracy and speed of FWHM calculation is obtained. Finally, a set of sharpness evaluation methods suitable for GWAC real-time auto-focusing are obtained. In this paper, the calculation error of FWHM is 0.046 pixel, the accuracy is equal to that of IRAF, and the focal point is the same. The calculation time of single chart (about 300 stars selected) is 0.67 s, about 1 / 20 of the computing time of IRAF, which meets the precision and real-time requirement of GWAC system auto-focusing. The results are applied in GWAC system. It can provide reference for other automatic telescope observation systems.
【作者单位】：中国科学院国家天文台空间天文与技术重点实验室;中国科学院大学;
【基金】：国家自然科学基金资助项目(No.U1331202,No.U1531134) 国家973重点基础研究发展计划资助项目(No.2014CB845800)
【分类号】：TH751;TP391.41

【相似文献】