Influence of the evanescent waves on the imaging characteristics of microspheres

We add a 20-nm-thick SiO film between a fully immersed BaTiO3 glass (BTG) microsphere and a sample with subdiffraction features, and study its imaging properties. Compared with a fully immersed BTG microsphere without the SiO film, the magnification becomes larger, and the initial image position is farther away from the sample. The imaging rules no longer satisfy the imaging rules used in geometrical optics. We propose that the thin SiO film can enhance evanescent waves and the enhanced evanescent waves affect the magnification and the image position in BTG microsphere imaging. Our studies will help to understand the imaging rules of microspheres more comprehensively.