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In conoscopic microscopy:
In conoscopic microscopy, the condenser aperture diaphragm
works as a field diaphragm on the conoscopic image surface. Stop
down the aperture diaphragm so it limits the periphery of the field
of view of the conoscopic image.
4.4
Field Diaphragm
The field diaphragm determines the illuminated area on the specimen.
Rotating the field diaphragm ring changes the size of the field
diaphragm. For normal observation, the diaphragm is set slightly
larger than the field of view. If a larger than required area is
illuminated, extraneous light will enter the field of view. This will
create a flare in the image and lower the contrast.
The thickness of the glass slide must be 1.7mm or less, otherwise the
field diaphragm may not be focused on the specimen plane.
The diaphragm does not have any effect when the condenser top lens
is swung out of the optical path. Fully open the field diaphragm, as
the numerical aperture of the illuminating system will be reduced if the
diaphragm is excessively stopped down.
4.5
Orientation of Polarizer and Analyzer
Slide in the analyzer slider to remove the analyzer from the optical
path.
Focus on the specimen.
Take the specimen out of the optical path.
Slide out the analyser slider to move the analyzer into the optical path.
Set the analyser to the “0” position by loosening the analyzer clamp
screw and rotating the analyser dial (the rotation angle of the analyser
can be read in the range between 0º to 360º in increments of 0.1º by
the Vernier scale).
