Multiple reflection effect inside a hemispherical solid immersion lens

The reflection inside a hemispherical solid immersion lens (h-SIL) is analyzed by using the film-interference optics and the new unique characteristic of the h-SIL is presented. The image theory of SIL microscopy is developed. Numerical results show that the reflection inside the h-SIL, especially for large mismatch in refractive indices between the SIL and the medium, has an important influence on the resolution of SIL surface microscope and the collection efficiency from the emitter. Theoretical and experimental results are compared through three examples, the reflection-mode microscope, the transmission-mode microscope, and the collection of light from the emitters. The present theoretical values are quite consistent with the experimental values in SIL microscopy. It is of interest to note that owing to the interference in the SIL, the resolution and collection efficiency periodically oscillate with the radius of an h-SIL, which mean that the radius of an h-SIL has to be well-controlled to achieve enough high resolution and collection efficiency.