Image enhancement using rough surface effects in plasmon materials

We investigate image enhancement of transmitted optical fields though plasmon film lenses with smooth surfaces, random rough surfaces, and sinusoidal rough surfaces. We show that the silver film lens with small periodic roughness can provide image enhancement. Image enhancement is defined by the spatial width of the image in the image plane. It is shown that the spatial width can be significantly less than a wavelength. It is also shown that the image integrity is preserved. On the other hand, random roughness does not preserve image integrity. In the formulation we consider a line source placed above the plasmon film lens with roughness. Two numerical methods, viz., method of moments and T-matrix method, are used to calculate the results.