Rigorous concept for the analysis of diffractive lenses with different axial resolution and high lateral resolution

We present a rigorous electromagnetic design and analysis of two-dimensional diffractive lenses (DLs) with different axial resolution and high lateral resolution. Without paraxial approximation, focusing characteristics of two kinds of DL, one with a long focal depth and a high lateral resolution, the other with high axial resolution and high lateral resolution, for f-numbers of 0.6, 1.0, 1.5, and 2.0 have been determined including the actual focal depth, the ratio between the focal depth of the designed DL and the focal depth of the conventional quadratic lens, and the spot size of the central lobe at the actual focal plane. Numerical and graphic results show that the designed DLs indeed have a long focal depth and a high lateral resolution, or high axial resolution and high lateral resolution by use of different preset focal depths.