Three-dimensional optical-transfer-function analysis for a laser-scan fluorescence microscope with an extended detector

Three-dimensional imaging characteristics of a laser-scan fluorescence microscope with various sizes of detector are quantitatively analyzed through the studies and calculations of the three-dimensional optical transfer function of the microscope. It is found that a detector of an Airy-disk size formed by the objective lens in the detector plane provides both reasonable energy-collection efficiency and three-dimensionally resolved imaging capability. It is also found that a slit detector provides longitudinal resolution of the sample structure similarly to a confocal microscope, while the lateral resolution is approximately the same as that of a conventional microscope.