6. Instrument setup– AdjustIng the dIAphrAgms
6. Startup
6.1 Adjusting the diaphragms
for the incident light illuminator
The following procedure is provided for incident light-bright
field illumination.
• Select an objective with moderate magnification (10x–
20x) and adjust the image.
• Activate the incident light axis if necessary.
• Switch on the BF (= brightfield) or Smith reflector.
• Place a specimen on the stage.
• Bring the specimen into focus and adjust the light inten-
sity.
Adjusting the field diaphragm
• Close the illuminated field diaphragm until the edge of the
diaphragm appears in the specimen plane.
• If the limits of the field diaphragm are not in the center of
the field of view, move the position of the field diaphragm
to the center with the two centering screws (Fig. 52.1) on
the right side of the stand using a 3 mm Allen key. When
centering, observe the position of the field diaphragm
through the eyepieces.
• Open the light field diaphragm until it just disappears from
the field of view.
• This setting of the field diaphragm remains the same for all
objectives.
It is necessary to readjust the field diaphragm only when
using eyepieces with different field numbers or when
changing the magnification using a magnification chang-
er, and for photography and TV imaging. Narrowing the
field diaphragm normally improves the contrast.
2
1
Fig. 52: Adjusting the diaphragms (incident light)
1
Adjusting screws for moving the field diaphragm
2
Adjusting screws for moving the aperture diaphragm
Adjusting the Aperture Diaphragm
• Use a flat specimen with good reflective properties, and a
glass plate (specimen carrier) if necessary.
• Remove one eyepiece (the right one, for example).
• Close the aperture diaphragm until the edge of the dia-
phragm appears in the exit pupil of the objective (aper-
ture diaphragm plane).
• If the image does not appear in the middle of the field of
view, the aperture diaphragm must be moved into the exit
pupil using the centering screws (Fig. 52.2).
• Open the aperture diaphragm until the speciment appears
in good contrast.
33
Summary of Contents for DMi8 A
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