二维光栅与周期性缝隙阵列组合薄膜结构的杂散光抑制

Suppression of the stray light of 2-dimensional gratings combined with an array of periodic slit

传统方格型二维光栅与周期性缝隙阵列的组合薄膜结构具有雷达和光学波段双带通的电磁特性.但由于其杂散光能量集中分布而严重制约它在高精度探测以及成像领域中的应用.本文提出了一种全新的组合薄膜结构,即由满足一定约束条件的圆孔型二维光栅和十字缝隙阵列构成.基于Fraunhofer衍射理论建立组合薄膜结构标量衍射模型,通过对比两种组合薄膜结构的衍射光分布,理论分析与实验测试均表明:圆孔型光栅与十字缝隙阵列组合薄膜结构不仅能够提高其光学透过率,而且还使其杂散光分布均匀,降低了其杂散光总比率,从而有效抑制杂散光,进一步增强了二维光栅与周期性缝隙阵列组合薄膜结构在实际光学系统中的可靠性.

An array of periodic slits, combined with classic grid two-dimensional gratings, can acquire a dual band-pass characteristic in radar and optical wave band. The concentrated distribution of stray light energy will severely restrict the applications of classic composite film structure in high precision detection and imaging. To solve this problem, a novel composite film structure is developed in this paper, which is composed of slit elements and annular gratings. A scalar diffractive model is built based on Fraunhofer diffractive theory through contrasting the diffractive properties of two kinds of composite film structures. The theoretical simulations and experimental results both prove that the annular composite film structure can suppress the stray light effectively, for its higher transmittance, lower ratio and more uniform distribution of stray light, and enhance the reliability of composite film structure in the practical optical applications.