金属网栅光学波段衍射分布研究

Diffraction Distribution in Optical Band of Metal Mesh

为了研究金属网栅高级次衍射产生的杂散光分布方式,进而在设计层面定量地控制网栅衍射能量分布,提升光学系统的探测能力,使用数学计算软件对不同结构形式金属网栅光学波段的衍射特性进行了建模和离散化仿真,利用快速傅里叶变换方法对不同结构的金属网栅在光学波段的衍射分布进行了离散化仿真计算。结果显示,周期性网栅的+1~+3级次衍射的归一化能量一般在-3~-2 dB级别,圆环网栅不会集中于轴向,并且随着衍射级次增加,衍射能量较方形网栅下降更快。随机网栅具有几乎完全均匀的衍射分布,并且高级次归一化衍射能量可控制在-6~-5 dB,远低于周期性网栅,使用在成像系统中能够将网栅衍射造成的杂散光匀化,降低背景噪声,提高成像质量。

In order to study the distribution of stray light generated by high-order diffraction of metal grids,and then quantitatively control the diffraction energy distribution of grids at the design level,and improve the detection capability of the optical system,mathematical calculation software is used to analyze the optical wavebands of metal grids with different structural forms in this paper.The diffraction characteristics are modeled and simulated discretely,and the diffraction distribution of metal grids with different structures in the optical band is simulated and calculated discretely by using the fast Fourier transform method.The results show that the normalized energy of the+1~+3 order diffraction of the periodic grid is generally at the level of-3~-2 dB,and the ring grid is not concentrated in the axial direction,and as the diffraction order increases,the diffraction energy drops faster than square grids.The random grid has an almost completely uniform diffraction distribution,and the high-order normalized diffraction energy can be controlled at-6~-5 dB,which is much lower than that of the periodic grid.It can be used in the imaging system to reduce the stray light caused by the diffraction of the grid.The homogenization can reduce background noise and improve image quality.