南方基地知识库

利用国内首个自上向下热蒸发反射膜的大型镀膜机ZZS3200,开展了2.4 m望远镜主镜镀膜工艺的研究。从镀膜的环境控制,镀膜机蒸发源布置,保护膜的选择,旧膜脱膜等方面出发,探索一种适合2.4 m望远镜主镜的镀膜工艺流程,并依此完成2.4 m望远镜主镜镀带MgF2保护的铝反射膜工作。陪镀片检测表明,铝膜膜厚极大极小值差43 nm,主镜反射膜在350~1 100 nm范围内平均反射率87.16%,经2.4 m望远镜实测,镀膜完成后极限星等不低于23.5 mag,比镀膜前约提高1 mag。2013年12月17日,在2.4 m望远镜上,利用终端云南天文台暗弱天体分光及成像仪(Yunnan Faint-Object Spectrograph and Camera,YFOSC),使用棱栅Grism3分光,对超新星SN 2011fe(V波段19.5 mag)成功进行光谱观测。30 min单幅曝光,获得暗于19 mag天体的光谱,刷新了该类天体在国内观测的新的记录。该目标在光谱观测的同时有相应的测光数据以及测光标准星观测,因此星等测量误差小于0.1 mag,可以用于定量分析。

In this paper we study technologies of adding aluminium coatings on the primary mirror of the 2. 4m optical telescope of the Yunnan Observatories. These are for operations with a large vacuum evaporation coating machine of the type ZZS3200,which is the first vacuum evaporation chamber to coat objects downward in China. We discuss some difficult issues of coating operations, including approaches to control the environment,arrange the evaporation sources of the coating machine,choose the protection film,and remove old coatings. Using these technologies we completed the coating of the primary mirror of the 2. 4m telescope with an aluminum reflection layer and an MgF2 protection layer. The average reflectivity of an accompanying plate in the coating (as the witness sample) is 87. 16% in the wavelength range from 350nm to 1100nm. After the coating the limit magnitude of the telescope reaches 23. 5 magnitudes, which is about 1 magnitude fainter than before the coating.