利用Zemax软件为线形离子阱囚禁199Hg+实验设计了一套光学系统, 该系统包括两部分, 即光学激发系统和荧光收集系统。光学激发系统由202Hg无极谱灯和激发透镜组组成。激发透镜组将202Hg无极谱灯的直径为15 mm的圆形面光源整形成23 mm×4 mm的矩形光去激发199Hg+能级跃迁, 从而使其辐射出荧光, 再利用荧光收集系统去收集该荧光。荧光收集系统由收集透镜组、滤波片和光电倍增管组成。设计结果表明: 该收集透镜组可以很好地将荧光发光面成像在直径为23 mm的光电倍增管上, 具有较高的荧光收集效率, 约3%。经物理系统实验, 结果表明, 该光学系统满足实验要求且具有较高的信噪比, 其值约为20。这为高性能线形199Hg+微波频标的工程应用提供了基础。

An optical system for trapped 199Hg+ in linear ion trap was designed by the Zemax software. The optical system consists of two parts which are optical excitation system and fluorescence collection system. The optical excitation system is composed of 202Hg electrodeless lamp and excitation lens system. The diameter of 15 mm surface light which is produced by 202Hg electrodeless lamp is transformed into rectangular light of 23 mm×4 mm by the excitation lens system. The rectangular light excites 199Hg+ atomic transition and then the 199Hg+ radiates fluorescence. The fluorescence is collected by the fluorescence collection system which is composed of collection lens system, filter and photomultiplier tube (PMT). The design results show that the fluorescence emitting surface is imaged well in the PMT whose diameter is 23 mm by the collection lens system. So the fluorescence collection is quite efficient and the collection efficiency is about 3%. Experimental results show that the optical system is completely satisfied for present experiment and it has a high signal to noise ratio (SNR) which is about 20. It makes necessary preparation for application of high-performance 199Hg+ microwave frequency standard.