microscopy
The use of, or investigation by means of, a
microscope. A microscope consists of an optical
device containing one or more lenses and is used
to view minute objects, generally those larger
than .005 mm. A one-lens instrument is known as a
simple microscope, while one with two or more
lenses is called a compound microscope.
Instruments which interpose oil of the same
refractive index as glass between the object and
the objective are used for high power work. The
limit of resolving power is equal approximately to
the wavelength of the light source used, i.e.,
points separated by 4 X 10-5 cm. Objects smaller
than this can be detected as bright points in the
ultramicroscope, while their actual shape and
dimensions can be examined in the electron
microscope, in which a beam of electrons is used
in lieu of light and is focused by electrostatic
or magnetic fields. Resolution down to 5 X 10-8 cm
is theoretically possible with such an instrument,
which is, however, difficult to use because of the
necessity of mounting the specimen in a vacuum.
The microscope is a valuable instrument for the
study of paper and leather fibers, etc. (195 )
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