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through the eyepiece, be sure that a uniform field of light is present with
no shadows at any edge of the field. The condenser is spring loaded at
the back of the stage and may be pushed in using the knurled center
knob. Once the optical axis is aligned, the diaphragm may now be
reopened to full diameter.
The viewfield of the microscope was factory set, and will rotate with a
little deviation off of center.
Just above the nose piece find a slot in the body tube. Note that it is
positioned between the polarizer and the analyzer polarizing lenses and
by convention runs in a southeast-northwest direction. The primary
purpose of this slot is to allow insertion of an accessory or retardation
plates between the polarizer and analyzer, in a specific orientation with
respect to the polarizer and the analyzer lens vibrational directions.
(Additional notes and descriptions of various kinds of compensators may
be found at www.ken-a-vision.com in a short primer on polarized light and
polarizing microscopy).
Focus
The basic principle involved in Polarizing Microscopy is to take
advantage of the fact that over 90 percent of all solid substances (aniso-
tropic) have optical properties that vary depending upon the orientation of
the incident light with the crystallographic axis. As specimens are exam-
ined under polarized light, there are refractive indices created which are
dependent upon both the propagation direction of light through the sub-
stance and on the vibrational plane coordinates due to the polarizing
lenses. The anisotropic specimen will act as a beam splitter, dividing light
rays into two parts. The polarizing microscope exploits this interference
of the split light rays as they are re-united along the same optical pathway.
Place a specimen slide under the stage clips. Using the coarse
adjust knob, lower the stage until the specimen is in focus. Use the
smaller fine adjust knob to now sharpen the focus and attain maximum
resolution. This first step may be done with the polarizing filters in or out
of the light pathway.
Using the Comprehensive Polarizing Scope - Polarizing
Microscopy
Good practice is to check your Comprehensive Polarizing Scope by
doing the following quick exercise. Do this without any specimen in the
light pathway to be sure that the polarizer and analyzer filters are correctly
aligned.
