同步辐射束流尺寸测量干涉仪的设计与仿真

Design and simulation of interferometer for synchrotron radiation beam size measurement

基于同步光的干涉法,是一种非拦截高精度的束流截面测量手段。相比传统成像法,干涉法可以测量更小的束团尺寸、分辨率更好,较短测量波长下有望获得亚μm级的分辨率,因此在同步辐射光源中得到广泛应用。对合肥光源HLS II的原有同步光干涉装置,提出了将原有的干涉光路中第一面聚焦透镜换成RC结构聚焦反射镜,第二面单透镜换成双胶合透镜,以达到在不改变光路光轴情况下减小色散和几何像差,从而提高光路成像质量的目的。采用几何光路设计方法对成像质量进行评价,并进行物理光学仿真计算,得到测量系统的干涉条纹。仿真结果表明:光学系统成像的艾里斑半径减小约35%,点列图的均方根半径减小了约99%,波前差也减小了约75%,调制传递函数(MTF)的截止频率提高了约65%,采用聚焦反射镜代替原有的聚焦透镜可大幅提升光路成像质量。

The interferometric measurement of the transverse beam size based on synchrotron radiation is a non-intercepting high precision measurement method.Compared with the imaging method,the interferometric method can measure smaller beam size and get better resolution.It is expected to obtain submicron resolution at shorter measurement wavelength,so it is widely used in synchrotron radiation sources.The upgraded scheme of current interference device in Hefei Light Source HLS-II is presented in this paper.It is proposed to replace the first focusing lens in the original interference light path with an RC structure focusing mirror,and the second single lens with a doublet lens.The design goal of this paper is to reduce dispersion and geometric aberration without changing the optical axis of the optical path,so as to improve the imaging quality of the optical path.The geometrical optical path design is used to evaluate the imaging quality of the optical path,and physical optical simulation is performed to obtain the interference fringes of the measurement system.The simulation results show that the radius of Airy spot is reduced by about 35%,the root mean square radius of dot array is reduced by about 99%,the wavefront difference is reduced by about 75%,and the cutoff frequency of MTF function is increased by about 65%,using a focusing mirror to replace the original focusing lens can greatly improve the image quality of the optical path.