根据研制宽视场大相对孔径高光谱成像仪的性能指标和应用要求，研究与设计了结构简单的凸面、凹面反射镜组成的偏视场两反前置系统。基于高斯光学和利用杨氏公式的像散分析，在系统焦距归一化条件下，凸面反射镜顶点曲率半径的取值区间为[2.5 mm, 3.24 mm)。给出根据指标要求确定系统初始结构参数的方法与结果。例如，优化设计得到的偏视场无遮拦像方远心两反前置望远物镜的工作波段为0.4~1.0 μm、相对孔径为1/1.8、视场角为40°。此镜头的两块反射镜面形均为扁球型二次曲面，具有结构简单、成像性能接近衍射极限、像方远心、及相对孔径大集光本领强、视场大且平像场的优点，可用作高空间分辨率、高光谱分辨率及高信噪比要求的成像光谱仪的前置物镜。

According to the performance and application of the hyperspectral imager with wide field of view and large relative aperture, a simple two-mirror fore objective with biased field of view consisting of one convex and one concave mirror is studied and designed. Based on its Gaussian optics and astigmatism analysis with Young′ s formulas and under the normalization condition with respect to the optical system′s focal length，the vertex curvature radius of the convex mirror should be chosen within the interval of [2.5 mm, 3.24 mm). The approach to determine its initial structural parameters which meet with expected performance and the corresponding results are presented. As an example, a fore two-mirror imagery telecentric objective with biased field of view for nonobscuration is optimally designed. Its working wavelength ranges from 0.4 to 1.0 mm, and its relative aperture and its linear field of view is respectively up to 1/1.8 and 40°. Both of mirrors are oblate ellipsoid surface with only conic coefficient. The designed lens has many advantages of simple and compact construction，near diffraction-limited imaging quality，imagery telecentricity, high speed and collection power，and wide and flat field of view. It will become the ideal fore objective of imaging spectrometers with high and spectral resolution and high signal-to-noise.