Confocal microscopy offers several advantages over conventional
widefield optical microscopy, including the ability to control depth of
field, elimination or reduction of background information away from the
focal plane (that leads to image degradation), and the capability to
collect serial optical sections from thick specimens. The basic
key to the confocal approach is the use of spatial filtering techniques
to eliminate out-of-focus light or glare in specimens whose thickness
exceeds the immediate plane of focus.