为满足高分辨率大相对孔径宽波段高光谱成像仪的要求,克服Offner光谱成像系统中凸面光栅加工的困难和改进型Czerny-Turner光谱成像系统相对孔径小的缺点,提出一种新型的基于平面光栅的大相对孔径Schwarzschild光谱成像系统,根据反射球面罗兰圆理论分析了该系统的像散校正方法,利用Matlab软件编制了初始结构快速计算程序。作为实例,设计了一个相对孔径为1/2.5,工作波段为400~1000 nm的Schwarzschild光谱成像系统。首先利用自己编制的Matlab程序计算初始结构参数,再利用Zemax-EE光学设计软件对该光谱成像系统进行光线追迹和优化设计,并对设计结果进行分析。结果表明,在整个工作波段内,点列图弥散斑的尺寸小于13 μm,实现了大相对孔径宽波段像差的同时校正,在宽波段内获得了良好的成像质量,满足设计指标要求,也证明了这种新型Schwarzschild光谱成像系统是可行的,其在航空和航天高光谱遥感领域具有广阔的应用前景。
To satisfy the requirement of high-resolution hyperspectral imager with a large relative aperture and a wide spectral region, and to avoid the difficulties of fabricating the convex grating in the Offner spectral imaging system and the problems of low relative aperture in the modified Czerny-Turner spectral imaging system, a neotype Schwarzschild spectral imaging system using planar grating with a large relative aperture is proposed. Based on the Rowland circle theory of the reflective spherical surface, the astigmatism-correcting method of the Schwarzschild spectral imaging system is analyzed. The initial parameters computing program is written using Matlab software. As an example, a Schwarzschild spectral imaging system operating in 400~1000 nm waveband with relative aperture of 1/2.5 is designed. First, the initial parameters are computed using our Matlab program, and then the ray tracing and optimization for the spectral imaging system are carried out with Zemax-EE software. The analyzed results demonstrate that the size of spot diagram is less than 13 μm in the whole working waveband, aberration correction is realized, and good imaging quality is obtained in a wide spectral region with a large relative aperture, which satisfies the requirement of design specifications, and proves the feasibility of the novel Schwarzschild spectral imaging system. It has extensive application prospect in hyperspectral remote sensing field.