A suitable place to put the sample in a surface plasmon microscope should have both stronger excitement and localization of surface plasmon (SP). We show that the behavior of localized SP depends on both the axial position of the sample and the number of axial spectrum components. For the special case of only one axial spectrum component, consistent good localization of localized SP exists over a quite wide range behind the lens, but the strongest excitement is adjacent to the lens. For the systems with small Fresnel number, which contain more axial spectrum components, the best location of the sample should be at the plane a little near the objective lens instead of at the geometric focal plane. The positive defocus amount should be avoided.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering