基于波前变换的自由曲面系统初始结构设计

Initial structure design of freeform surface system based on wavefront transformation

自由曲面具有良好的像差矫正能力,但没有足够的初始结构供设计者参考,因此研究自由曲面初始结构的设计方法是有意义的.通常初始结构设计方法为大量点和光线的追迹或数值求解微分方程组,运算量大且复杂。文章从光学系统对光波变换的角度出发,推导自由曲面解析表达式,并设计一款工作波段较宽,相对口径较大的离轴红外光学系统,工作波段3~12μm,焦距300mm, F/2.5,视场角2.04°×2.56°,像质接近衍射极限且100%冷光阑效率,全视场波像差RMS值平均为0.059λ@3.67μm.

As the number of initial structures is not enough for optical designers need,it is significant that methods of freeform surface are studied,because freeform surface is able to eliminate aberrations greatly.The design methods of initial structures are usually ray tracing or numerically solving of differential equations to construct point clouds,it is complex and costing largely of computing.A new method deriving the formulas of freeform surface in a view that optical system changes wave front was presented,and an infrared off-axis optical system with large relative aperture and wide working spectrum 3~12μm,focal length is 300mm,F/2.5,full field of view is 2.04°×2.56°was designed using this method.This system is with high quality of image(diffraction limit)and 100%cold stop efficiency,0.059@3.67μm average RMS wavefront error.