Improvements of axial resolution in confocal microscopy with fan-shaped apertures.

Based on diffraction theory, this paper theoretically demonstrates improvements in axial resolution in confocal microscopy with fan-shaped apertures. It provides the optimal geometric parameters of the fan-shaped pupils to give the maximum axial resolution for a given pinhole size. To fully understand the overall performance, the signal-to-background ratio and the signal level with regard to the geometric parameters are discussed.