Dark
field microscopy is a method which also creates
contrast between the object and the surrounding
field. As the name implies, the background is dark
and the object is bright. A annular stop is also
used for dark field, but the stop is now outside
the field of view. Only light coming from the outside
of the beam passes through the object and it cannot
be seen directly. Only when light from the stop
is deflected and deviated by the object can it be
seen. This method also produces a great deal of
glare and therefore the specimen often appears as
a bright silhouette rather than as a bright object
of which much detail can be determined. The following
diagram shows the setup of the dark field light
path.
(Redrawn from Gray)* Please
remember that when using dark field optics, that any
dirt or dust or other garbage on your slide or specimen
will shine just as brightly as your object of interest.
Make sure your slide is immaculately clean.
*Diagram
redrawn from Gray , P. 1964. Handbook of Basic Microtechnique
McGraw-Hill: New York.
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