银薄膜对光学基底表面粗糙度及光散射的影响

Influence of Ag Thin Films on Surface Roughness and Light Scattering of Optical Substrate

为了研究金属银薄膜与光学基底表面粗糙度和光散射的关系,提出了通过对光学薄膜矢量散射公式积分来获得界面粗糙度完全相关模型和完全非相关模型下其表面的总反射散射的方法.理论计算了光学基底上两种模型在不同厚度银膜下的总反射散射和双向反射分布函数.结果表明,当沉积在光学基底上的银薄膜的厚度大于80nm后,两种模型下计算的银薄膜的表面总反射散射都等于基底的总积分散射,银薄膜能较好地复现出基底的粗糙度轮廓.实验研究表明为了复现基底的粗糙度,银薄膜的最佳厚度应在80～160nm之间.

In order to investigate the relationship of Ag thin films and optical substrate surface roughness and light scattering, a new method was presented, of which total reflectance scattering was obtained by integrating vector light scattering expression, bidirectional reflectance distribution function（BRDF）, at interfaces roughness perfectly correlated and completely uncorrelated model respectively. Total reflectance scattering and BRDF of Ag thin films on optical substrates were calculated at different thickness of Ag thin films for these two theoretical models. The results of theoretical calculation show that when the thickness of Ag thin films deposited on optical substrate is thicker than 80nm,total reflectance scattering of Ag thin films equate to total integrated scattering. This time Ag thin films can perfectly replicate surface profile of optical substrate. And, experiments of different Ag thin films deposited on identical surface root mean square roughness were carried on. The results show that the thickness of Ag thin films is at 80-160 nm, and Ag thin films can perfectly replicate substrate roughness profile.