OPERATION
ZEISS
Illumination and contrast methods in transmitted light …
Axioscope 5/7/Vario
92
430035-7344-001
03/2018
(5) Setting darkfield contrast with immersion oil darkfield condenser
•
If necessary, swivel out the low-power system, polarizer or
λ
plate.
•
Move the condenser carrier down until the end stop.
•
Place the immersion oil darkfield condenser in the condenser holder Z (see section 3.1.14).
•
Place the condenser holder Z in the condenser carrier and center it roughly, so the condenser fits into
the opening of the mechanical stage without contact, when moving upwards.
•
Move the condenser up until the end stop.
•
Place a drop of immersion oil (without bubbles, if possible) on the center of the condenser front lens.
•
Place a specimen. The immersion oil will disperse between condenser and specimen holder.
•
Slightly move the mechanical stage back and forth to dissipate any air bubbles in the immersion oil.
•
Adjust the illumination intensity to bright enough and open the field diaphragm completely.
•
Swivel in an objective with small magnification (e.g. 10x) and focus the specimen, using the focusing
drive.
•
Center the field diaphragm on the condenser carrier with the adjustment screws and focus the image
with the condenser drive.
•
Place a drop of immersion oil on the specimen holder, swivel in immersion oil objective and focus the
specimen.
•
Close the field diaphragm until the end stop.
•
Lower condenser until edge of field diaphragm appears sharp.
•
Center the field diaphragm image with both centering screws on the condenser carrier.
The luminous field diaphragm appears only as a circle segment on the edge of the viewing field due to
the high magnification of the immersion oil objective. As a result, the focusing and centering of the field
diaphragm must be repeated. If necessary, the luminous-field objective should be opened slightly if the
light intensity is too low.
The field diaphragm is centered properly when the edge of the luminous field diaphragm is centered or
equidistant from the viewing field edge.
•
For a sharply focused specimen, open the sharply set field diaphragm enough to make the edge of the
diaphragm disappear from the field of view.
•
You can improve the contrast of the microscope image by slightly adjusting the focus level of the
condenser with the condenser drive.
•
The background of the eyepiece image should appear equally dark.
•
For immersion oil objectives with an iris diaphragm, the contrast can be further optimized by turning
the adjustment of the iris diaphragm.
