14
STEINDORFF
®
Fig. 29
Fig. 30
Fig. 31
The image of aperture iris diaphragm
Polarizer
①
Analyzer
Coupling plate
②
④
③
3.12.
Centering the Aperture Iris Diaphragm (AS)
1.
Slide the mirror selector lever to “BF”.
2.
Engage the 10X objective by rotating the revolving
nosepiece, place the specimen on the stage and adjust
approximate focusing.
3.
Remove the eyepiece, look into the eyepiece sleeve and pull
the AS knob
⑤
, so that the aperture is about 70%.
4.
If the center of the iris diaphragm is deviated, center it by
rotating the two AS centering screws
③
(Fig. 27) using the
Allen screwdriver.
Using the Aperture Iris Diaphragm
In reflected light brightfield observation, optimum
observation is generally possible by setting the aperture to
between 70% and 80% of the aperture number of the
objective (fig. 29).
In reflected light darkfield observation, the aperture must be
fully opened by pushing in the AS knob.
o
With some specimens, an image with high contrast and little
flare may sometimes be obtained when the aperture is
slightly closed. It is therefore recommended to also try a
slightly closed aperture.
3.13.
Setting the Analyzer and Polarizer
1.
Insert the polarizer (Fig. 30) into the polarizer insertion Slot
③
with the surface printing with Silk Screen towards you,
then push the polarizer into the light path.
2.
Remove the cover, then put the analyzer (Fig. 30) in the
insertion slot
②
(Fig. 31).
3.
Rotate the analyzer rotating dial
①
to find the position
where the field of view is darkest.
4.
When the analyzer and polarizer are coupled by using the
coupling plate | provided with the polarizer and tightening the
clamping knobs on it, the analyzer and polarizer can be
engaged or disengaged in the light path together (Fig. 31)
