光学薄膜减散射特性研究

为了降低光学薄膜的表面散射损耗,依据微粗糙面的一阶微扰理论,在不考虑多重散射效应的情况下,利用电磁场边界条件给出的光学薄膜任一界面粗糙度引起的散射场在入射介质中的表达式,重点讨论了单层光学薄膜实现零散射的条件以及实现减散射的条件,理论研究结果表明:当膜层的光学厚度为/4的偶数倍时,单层薄膜要实现减散射就必须使单层膜的折射率大于基底的折射率,且空气-薄膜界面的微粗糙度必须小于薄膜-基底界面之间的微粗糙度。当膜层的光学厚度为/4的奇数倍时,单层薄膜的折射率小于基底的折射率,且膜层两个界面的粗糙度必须满足特定条件,才能实现减散射的效果。

Anti-scattering properties of optical thin film

In order to reduce the surface scattering loss of optical thin film, the expression of interface roughness scattering field in the incident medium was given by electromagnetic field boundary conditions, without considering the effect of multiple scattering. The conditions of zero scattering and anti-scattering of single layer optical thin film were discussed. The theoretical results show that when the optical thickness of the film is an even time of /4, the refractive ratio of the single layer thin film must be bigger than the substrate refractive ratio so as to realize anti-scattering, and the air-film micro-roughness must be smaller than the film-substrate interface micro-roughness, when the optical thickness of the thin film is /4 an odd number of times, single layer optical thin film to realize anti-scattering must be single-layer thin film refractive index is less than the substrate refractive index, and the air-film micro-roughness must be satisfy certain conditions.