OPERATION
ZEISS
Illumination and contrast methods in transmitted light
Axiolab 5
86
430037-7444-001
05/2019
(5) Setting darkfield contrast with the 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 3.1.9).
•
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 to the end stop.
•
Place a drop of immersion oil (without bubbles, if possible) on the center of the condenser.
•
Position a specimen. The immersion oil will disperse between the condenser and specimen holder.
•
Move the mechanical stage back and forth slightly to dissipate any air bubbles in the immersion oil.
•
Adjust the illumination intensity so that it is bright enough and open the field diaphragm completely.
•
Swivel in a low-magnification objective (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 the immersion oil objective and focus
the specimen.
•
Close the field diaphragm down to the end stop.
•
Lower the condenser until the edge of the 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 edges of the viewing field.
•
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 evenly dark.
•
For immersion oil objectives with an iris diaphragm, the contrast can be further optimized by turning
the adjustment wheel of the iris diaphragm.
