Darkfield Observation - Optika Italy B-510 Serie Manual De Instrucciones

12.4 Condenser centring for darkfield
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.
5. Reposition the slide and raise the condenser until the oil on
the lens of the condenser is in contact with the slide.
6. Move the area to be observed at the center of the optical path
using a low magnification objective (10x or 40x).
7. Focus the specimen.
8. Insert in the light path 100X oil/Iris objective. This pre-
positions all system components in preparation for adding
oil. Move the immersion objective to an adjacent position
of the nosepiece and apply the oil to the sample. (Fig. 27)
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