Electromagnetic description of image formation in confocal fluorescence microscopy

Using an electromagnetic approach, we calculate the properties of a confocal fluorescence microscope. It is expected that the results will be more reliable than those obtained by conventional scalar theory, the results of which differ significantly from ours. We calculate the point-spread function and the optical transfer function and study the influence of detector size and fluorescence wavelength on the optical sectioning capability. Our calculations are based on electromagnetic diffraction theory in the Debye approximation. The recently noted asymmetry between the illumination and the detection sensitivity distribution is also taken into account.