软X射线掠入射望远镜的成像质量评价

Imaging quality evaluation of soft X-ray grazing incidence telescope

为了评价软X射线掠入射望远镜的成像质量,提出了一种利用ZEMAX和MATLAB相结合的像质评价方法。根据这种方法编写的像质评价程序不仅考虑了孔径衍射、几何像差和装调误差等因素对成像质量的影响,而且加入了望远镜面形误差和X射线散射效应的影响。利用勒让德-傅里叶多项式和用户自定义表面,在ZEMAX中建立带有面形误差的筒状反射镜表面模型,实现对真实面形的掠入射反射镜的仿真;根据Harvey-Shack散射理论建立了ZEMAX中的BSDF散射模型,实现对X射线散射的仿真。搭建X射线有限远成像实验装置,对像质评价程序进行了验证。实验结果和仿真结果对比表明实验光斑和仿真光斑的光强分布基本一致,以实验结果为基准,仿真光斑的半高全宽横向和纵向的相对误差分别为14.7%和11.3%。说明像质评价程序的仿真结果基本符合真实情况,对掠入射光学系统的设计和加工具有一定的指导意义。

In order to evaluate the imaging quality of the soft X-ray grazing incidence telescope,an image quality evaluation method using ZEMAX and MATLAB is proposed.The image quality evaluation program written according to this method not only considers the aperture diffraction,the geometric aberration and the alignment errors,but also adds the telescope surface figure errors and the surface scatter effects.Using the Legendre-Fourier polynomial and User Defined Surface,a cylindrical mirror model with figure errors is created in ZEMAX,to simulate the real surface profile grazing incidence telescope.The BSDF scattering model is established according to the Harvey-Shack surface scattering theory to simulate X-ray scattering.The X-ray finite distance imaging experimental facility is built for verifying the image quality evaluation program.The comparison between the experimental results and the simulation results of the image quality evaluation program shows that the light intensity distribution of the experimental spot and simulation spot is basically the same.Using the experimental result as a standard,the relative errors of the horizontal and longitudinal directions of the simulated spot FWHM were 14.7%and 11.3%,respectively.It is proved that the simulation results of the image quality evaluation program are credible and have certain guiding significance for the design and processing of the grazing incidence optical system.