Vision Engineering TIM5 User Manual page 15

The image of aperture iris diaphragm
Fig.29
Polariser
Analyser
Coupling plate
Fig.30
②
④
Fig.31
3-12
1.
2.
3.
4.
Using the Aperture Iris Diaphragm

①

 With some specimens, an image with high contrast and little flare
3-13
1.
2.
③
3.
4.
Centring the Aperture Iris Diaphragm (AS)
Slide the mirror selector lever to "BF".
Engage the 10X objective by rotating the revolving nosepiece,
place the specimen on the stage and adjust approximate focusing.
Remove the eyepiece, look into the eyepiece sleeve and pull the AS
knob (⑤ in Fig.27), so that the aperture is about 70% open.
If the centre of the iris diaphragm is deviated, centre it by rotating
the two AS centring screws (③ in Fig. 27) using the Allen key.
When observing using the reflected light brightfield function,
optimum observation is possible by setting the aperture to
between 70% and 80% of the aperture number of the objective
(Fig.29).
When observing using the reflected light darkfield function, the
aperture must be fully opened by pushing in the AS knob.
may sometimes be obtained when the aperture is slightly closed. It
is therefore recommended to also try a slightly closed aperture.
Setting the Analyser and Polariser
Insert the polariser (Fig. 30) into the polariser Insertion Slot ③
(Fig.31) make sure the surface printing with Silk Screen is facing
towards you, and then push the polariser into the light path.
Remove the cover, and then put the analyser (Fig.30 in the
insertion slot ② in Fig.31).
Rotate the 'analyser rotating dial' (① on Fig.30) to find the
position where the field of view is darkest.
When the analyser and polariser are coupled by using the coupling
plate (Fig.30) provided with the polariser and tightening the
clamping knobs on it, the analyser and polariser can be engaged
or disengaged in the light path together (Fig.31).
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