Uniform axial intensity distributions of long-focal-depth cylindrical micromirrors realized by an amplitude-phase modulation method

摘要

An amplitude-phase modulation method (APMM) is applied to realize the uniform long-focal-depth (LFD) function of metallic cylindrical focusing micromirrors (MCFMs). Based on rigorous electromagnetic theory and the boundary element method, focal properties of the designed MCFMs are characterized, which contain the actual focal depth, the focal spot size, the normalized encircled energy, the real focal length, and the axial intensity uniformity. On appropriately choosing the incident amplitude distribution with apodization, the designed MCFMs demonstrate the LFD properties with uniform intensity distributions. The superiority of the APMM to the pure phase modulation method is revealed in achieving a higher normalized encircled energy.