OPTIKA MICROSCOPES B-500DK Manual De Instrucciones página 12

4.0 B-500DK DARKFIELD MICROSCOPE CONFIGURATION
• 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 Figure 5(a). As the condenser is slightly raised or lowered,
a dark spot similar to the one shown in Figure 5(b) will appear, 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 Figure 5(c). The ideal and correct positioning of the
condenser is illustrated in Figure 5(a), and the condenser should be adjusted until the field of
view appears in this manner, with the condenser centering screws.
• To apply oil to the immersion condenser, remove the microscope slide and slowly rack the
condenser down below the mechanical stage and place a drop of oil directly on the front
lens.
• Replace the slide, then slowly raise the condenser until contact is made between the oil dro-
plet and the bottom surface of the slide. Carefully observe the oil contact area to determine if
any air bubbles have been introduced into the space between the condenser top lens and the
microscope slide. It should be noted that no matter what the magnification of the objective is,
if an oil immersion condenser is used without oil, light will not emerge from the condenser.
Air bubbles will scatter light and should be observable by removing the eyepiece and viewing
the back focal plane of the objective with a centering telescope.
If no bubbles are present, proceed on to the next step. When bubbles are detected, remove
all traces of oil from both the slide and the condenser top lens and repeat the procedure.
Make certain both surfaces are clean and completely free of oil, dust, dirt and other contami-
nating artifacts before re-oiling the condenser.
Page 12