12
c. When viewing is complete, all parts that have come into contact with
the oil must be cleaned using a soft cotton cloth, lightly dampened
with Xilene. If the 100X objective is not cleaned, the oil will dry, and it
will not be possible to see through it; permanent damage could
also
occur.
NB. Immersion oil must ONLY be used with the 100X objective, as it is the
only one specially prepared for it. If any other objective comes into
contact with the oil, it must be cleaned immediately.
E. Critical illumination for models with focusable 1.25 N.A.
Abbe
condenser
The ideal level of illumination is when all illumination elements are brought
into proportion, basically, by the condenser. To achieve critical illumination
an object over the illuminator must be in focus.
1. Focus on slide with the 10X objective.
2. Place a flat object on the illuminator. The object must be one that lets
light through, a slide for example.
3. Without letting go of slide, focus, using the other hand to turn the collar to
move
the
condenser.
4. When critical illumination is achieved, the slide can be removed. If any
irregularity appears in the field of view, i.e. an optical element from the
focussed illuminator, move the condenser just enough to take it out of
focus, thus obtaining the best level of illumination possible, and
closest to critical illumination.
