Axial resolution in wide-field (WF) and confocal microscopes. Three-dimensional stacks of images of a 0.2-µm diameter fluorescent bead were collected in a WF, disk-scanning, or spot-scanning confocal microscope. The graph shows the total integrated intensity from the bead in different focal planes, individually normalized for each microscope. The intensity profile in the WF images after deconvolution is also shown. The intensity recorded by the disk-scanning confocal microscope falls off exactly as with the spot-scanning microscope for small values of defocus but then plateaus and remains constant while the spot-scanning intensity continues to decrease to 0.