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OPERATION
ZEISS
Illumination and contrast methods in reflected light
Axiolab 5
112
430037-7444-001
05/2019
4.3
Illumination and contrast methods in reflected light
4.3.1
Configuring reflected light brightfield microscopy using the KÖHLER method
(1) Application
Reflected light brightfield microscopy is the simplest and most common optical microscopy method for
examining opaque samples or specimens, e.g. material sections or wafers.
For a true-to-object imaging, indirect ray bundles, i.e. ray bundles diffracted and scattered on the
specimen details, are of major importance in addition to the so-called direct ray bundles. The higher the
proportion of indirect bundles of rays (aperture), the more realistic the ABBE microscopic image will be.
The cone of light emitted by the reflected light unit is reflected on a color-neutral beam splitter and then
passes through the objective, which focuses the beam on the surface of the sample (so-called condenser
function). The objective collects the light reflected by the specimen, and together with the tube lens it
generates the microscopic intermediate image which can then be visually observed or objectively
documented.
(2) Instrumentation
Reflected light brightfield viewing is possible only with the stand for reflected light.
−
P&C ACR brightfield reflector module for reflected light in the reflector turret
(3) Configuring reflected light brightfield microscopy
−
The microscope has been started up correctly as described in section 3.
−
The microscope is switched on.
•
Adjust the light intensity by turning the Intensity/LM knob (Fig. 4-19/
4
).
•
Position a high-contrast reflected light specimen on the microscope stage.
•
Swivel in the 10x objective on the nosepiece (Fig. 4-19/
3
).
•
On the nosepiece (Fig. 4-19/
6
), swivel in the position with the brightfield reflector module.
•
Bring the specimen into focus with the focusing drive (Fig. 4-19/
5
). If possible, always focus away from
the specimen in order to avoid a collision between the objective and the specimen.
•
Set the knurled wheel of aperture diaphragm
A
1
) in the middle position (about half
open/closed).
•
Adjust the knurled wheel of the luminous-field diaphragm
F
2
) until the luminous-field
aperture is visible in the field of vision.
•
Use the focusing drive to adjust the focus on the edge of the luminous-field aperture.
•
Now open the luminous-field aperture until it disappears just beyond the edge of the field of view.
•
To adjust the aperture diaphragm (image contrast), remove an eyepiece from the eyepiece tube and
look into the tube with the naked eye, or use the auxiliary microscope instead of the eyepiece.
This functions only with sufficiently reflective specimens.