广角天文望远镜的自动调焦

发布时间：2018-04-03 04:25

本文选题：广角天文望远镜　切入点：自动调焦　出处：《光学精密工程》2015年01期

【摘要】：介绍了一种基于步进电机(无位置检测传感器)和像质反馈的广角天文望远镜自动调焦系统,该系统由步进电机位置开环控制系统和图像清晰度评价系统组成。基于天文图像的特点,提出利用天体点源星像的半高全宽(FWHM)作为图像清晰度的评价参数;为了提高系统精度,对定位控制系统进行了误差分析;测定了调焦当量、光学焦深、系统回差、步进脉冲当量等系统关键机构参数,进而高精度地修正了系统定位误差;分析和测定了温度变化和像质变化的相关性,明确了调焦方向和温度变化之间的定性关系;设计了焦深边缘定位策略,实现了快速调焦。该系统具有"容错"和"自学习"功能,具有较高的自动化和智能化程度。将系统设计应用于SVOM天文卫星地基广角相机阵[1-2](GWAC),实际测试和天文观测表明,调焦系统的定位精度为±3.0μm,调焦精度为0.05pixel,且一次调焦过程即可获得最佳像质,调焦效率较高,系统运行也很稳定,基本满足天文观测的需求。
[Abstract]:An automatic focusing system for wide-angle astronomical telescope based on stepping motor (without position detection sensor) and image quality feedback is introduced. The system consists of an open-loop control system for stepping motor position and an image definition evaluation system.Based on the characteristics of astronomical images, the FWHM of celestial point source star images is proposed as the evaluation parameter of image sharpness. In order to improve the accuracy of the system, the error analysis of the positioning control system is carried out, and the focusing equivalent and optical focal depth are measured.The key mechanism parameters, such as system return error, step pulse equivalent and so on, are corrected with high accuracy, the correlation between temperature change and image quality change is analyzed and measured, and the qualitative relationship between focusing direction and temperature change is clarified.The focal depth edge location strategy is designed, and the fast focusing is realized.The system has the functions of "fault tolerance" and "self-learning", and has a high degree of automation and intelligence.The system design is applied to the SVOM astronomical satellite ground-based wide-angle camera array [1-2]. The actual measurement and astronomical observation show that the positioning accuracy of the focusing system is 卤3.0 渭 m, the focusing accuracy is 0.05 pixel, and the best image quality can be obtained during the single focusing process, and the focusing efficiency is high.System operation is also very stable, basically meet the astronomical observation needs.
【作者单位】：中国科学院国家天文台;中国科学院大学;
【基金】：国家自然科学基金资助项目(No.U1331202) 国家973重点基础研究发展计划资助项目(No.2014CB845800)
【分类号】：P111.2

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