Dr. Sandison et Ww. Webb, BACKGROUND REJECTION AND SIGNAL-TO-NOISE OPTIMIZATION IN CONFOCAL ANDALTERNATIVE FLUORESCENCE MICROSCOPES, Applied optics, 33(4), 1994, pp. 603-615
In the confocal microscope, tightly focused illumination and spatially
filtered detection are combined to reduce out-of-focus background and
to produce high-quality images that display thin optical sections wit
hin thick fluorescent specimens. We define background as the detected
light that originates outside a resolution volume and signal as the de
tected light that originates within the same volume. Background reject
ion is measured by the signal-to-background ratio (S/B) and is calcula
ted for confocal, spinning-disk, line-illumination, slit-detection, an
d conventional fluorescence microscopes as a function of both the spat
ial filter size and the specimen thickness. Spatial filter sizes that
reject background and optimize the signal-to-noise ratio (S/N) are cal
culated for each microscope. These calculations are normalized so that
the time-averaged illumination at each point in the specimen is the s
ame for each microscope. For thick specimens, we show that the S/B obt
ained with a confocal microscope can be more than 100 times greater th
an the S/B available with a conventional microscope, and we find that
the optimal confocal S/N can be a factor of 10 greater than the S/N in
the conventional microscope.