云南1m太阳塔真空封窗减反射膜的设计

云南1m太阳塔(YNST)1]是一个真空结构的塔式太阳望远镜,依靠4块平板封窗玻璃把整个光学系统密封在真空系统中。封窗玻璃的引入,不仅会对太阳光有一定的吸收和反射,使来自太阳辐射的能量有一定的损失,并会形成杂散光,影响成像质量。本文讨论了这些影响。根据云南1m红外太阳塔科学指导委员会确定的工作波段的要求,设计了一种膜系设计方法,可以利用最少的膜系层数来达到需要的结果。并用一组材料进行了模拟设计实验,获得了较为理想的优化结果,在关键波长处显著减小了反射率,减少了杂散光的形成。这种设计方法很适合象太阳塔这种很宽的波段里面对一组波长有很高要求的设计任务,将大大提高光能利用率,具有重要的价值。

Design of Antireflection Coating on Vacuum Windows for the Yunnan 1m Solar Telescope

The Yunnan 1m Solar Telescope(YNST) is a vacuum telescope. It uses four flat vacuum windows to seal off the vacuum. The entire light transmitance will be reduced by the vacuum windows, and a part of the reflected light will change into the scattered or stray light. In this paper the influence of the vacuum window is analyzed. Based on the suggestion of the YNST Science Case Group, an optimum technique has been used to determine the layer thickness for a coating design. The coating will include minimal layers to maximize the energy throughput of the system on the key wave, and minimize the scattered or stray energy. In this way, the antireflection coating over a wide wavelength interval can easily be gotten, and the ratio of utilization of the optical energy can be increased.