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衍射聚焦器件轴向光强分布的焦深和焦移特性 ,直接决定着系统接收面的装配误差和获得最佳的能量利用率。当器件的口径和面型特征尺寸可与照射波长比拟时 ,必须考虑光波与衍射器件的电磁作用。利用严格电磁分析方法——时域有限差分法 ,对有限口径衍射微柱透镜的轴向光强分布进行了严格分析 ,并且与传统的标量分析方法进行详细比较。分析比较了 TE和 TM极化波入射情况下 ,不同面型分布 (8台阶 ,1 6台阶量化面型和连续面型 )的衍射微柱透镜焦深和焦移特性与透镜 F数的关系。结果表明透镜轴向光强最大点向透镜面偏移 ,焦移量的严格计算结果要大于标量计算结果 ,表明透镜的快聚焦特性 ,而二者得到的焦深量基本一致 ,同时两种理论方法都表明透镜焦深和焦移随 F数的增加而增加。
The focal depth and focal shift characteristics of the axial intensity distribution of the diffractive focusing device directly determine the assembly error of the receiving surface of the system and obtain the best energy utilization. When the device diameter and surface feature size with the irradiation wavelength comparable, we must consider the light wave and the diffraction of electromagnetic devices. Using the strict electromagnetic analysis method - time-domain finite difference method, the axial intensity distribution of a finite-aperture diffractive micro-cylindrical lens is strictly analyzed and compared with the traditional scalar analysis method. The relationship between the focal depth and focal shift characteristics of diffractive micro-cylindrical lenses and the F-number of the lens with different surface distributions (8 steps, 16 steps of continuous surface and quantized surface) were analyzed and compared under the incident wave of TE and TM polarized waves. The results show that the maximum lens focal point axial shift to the lens surface, the exact calculation of the focal shift is greater than the scalar calculation results, indicating the fast focusing lens characteristics, and the two obtained the same depth of focus, while the two theories The methods all show that the lens focal depth and focal shift increase with increasing F number.