基于折/衍混合原理的长焦深成像物镜消色差方法

An achromatic method for optical imaging objective with long focal depth based on hybrid refractive-diffractive principle

为兼顾成像系统消色差及扩展焦深的特性,提出了一种基于折/衍混合原理的长焦深成像物镜在可见光波段内消色差的方法。通过阐述对数光锥位相结构的特征,讨论了长焦深元件的色散特性,并依据折/衍混合消色差原理,确定长焦深成像物镜中折射元件与衍射元件位相函数重新分配的原则;位相重新分配后,衍射元件在承担扩展焦深功能的同时增加了部分消色差光焦度,从而使长焦深元件获得消色差特性。理论和仿真分析表明,位相函数重新分配后得到的长焦深元件在中心波长λd(587 nm)时的轴向光强分布与原长焦深元件一致,而在波长为λF(486 nm)、λc(656 nm)时的轴向光强分布区域重合,即在保留焦深扩展特性的同时,有效地校正了其在可见光波段内的初级色差。

For the purpose of studying the characteristics of achromatic aberration and focal depth extension, an achromatic method in visible band was presented for the optical imaging objective with long focal depth based on the refractive-diffractive hybrid objective. By analyzing the formation of logarithmic phase, the dispersion of a element with long focal depth was discussed. According to the refractive-diffractive hybrid achromatic principle, the phase distributions of the refractive and diffractive elements were restructured. In novel objective system, the diffractive elements were employed in extending the focal depth and improving the achromatic focal power. Compared with traditional objective system, the simulation results show that the on-axis intensity distribution of the achromatic hybrid refractive-diffractive objective based on novel phase relationship is unaltered in central wavelength ,λd （587 nm）, and they are the coincidence in achromatic wavelength of λF（486 nm） and ;λc（656 nm）.