Effects of fabrication errors on MTF and diffraction efficiency for binary optical lens

Since the performance of binary optical element (BOE) is affected vastly by etching depth error, mask misalignment and feature rounding introduced by the fabrication process, it becomes important to analyze the effects of fabrication errors on the BOE. The phase pattern of binary optical lens will not be symmetrical when the misalignment error exists, and it is very complicate to analyze the diffraction efficiency. Based on the relationship between the diffraction efficiency and the modulation transfer function (MTF), the MTF of a binary optical lens with different fabrication errors is calculated, and the effects on diffraction efficiency are also obtained.