Darkfield Observation - Optika B-380 Serie Manual De Instrucciones

11.4 Darkfield observation
1. Select a darkfield specimen and place it on the
microscope.
2. Insert 10x objective in the light path and focus the
specimen.
• The condenser will project a spot of light onto
the sample that can be used for centering the
optical path.
3. Use the condenser centering screws to move the
ring of light into the center of the field of view ①.
(Fig. 24)
• It could be useful to vary the height of the
condenser in order to view the spot.
• It is often advantageous to use a low power
10x objective when centering high numerical
aperture darkfield condensers.
• When viewing a specimen with the 10x
objective while slowly raising and lowering
the condenser, a point will be reached where
a bright spot will appear in the field of view
as illustrated in Fig. 25(a). As the condenser
is slightly raised or lowered, a dark spot
similar to the one shown in Fig. 25(b), if the
condenser is properly centered. In cases
where the condenser is not properly aligned
and centered, a typical field of view might
look like that shown in Fig. 25(c) and (d). The
ideal and correct positioning of the condenser
is illustrated in Fig. 25(a), and the condenser
should be adjusted until the field of view
appears in this manner, with the condenser
centering screws.
4. Remove the slide and put a drop of oil (provided)
on the condenser front lens. (Fig. 26)
• Make sure there are no air bubbles. Air bubbles
in the oil damage the quality of the image.
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①
Fig. 24
Fig. 25
Fig. 26