Superresolution imaging with focused radially polarized beam
Focused radially polarized beam is used to image non-fluorescent specimens to enhance the spatial resolution of conventional confocal microscopes.
With pupil engineering of the common radially polarized illumination, a more tight focal spot can be obtained. Combining this character with a confocal laser scanning system, we can demonstrate both numerically and experimentally that this condition can offer spatial resolution improvements for imaging.
Rigorous vectorial focusing theory is presented in this paper for imaging small
particles next to each otherwith a confocal laser scanning system.We consider radially polarized illumination with an optimized amplitude distribution and an annular lens to obtain a narrower spot size of the longitudinal component of the field in focus.
A polarization convertor at the detector side is added to transform radial polarization to linear polarization in order to make the signal detectable with a single mode fiber.