OPERATION
Axio Imager
Illumination and contrast methods
Carl Zeiss
M70-2-0020 e 06/2009
430000-7344-001
145
4.9
Illumination and contrast methods
4.9.1
Setting transmitted-light brightfield according to KÖHLER
(1) Application
Transmitted-light brightfield microscopy is the most common of all optical microscopic techniques, as it
permits high-contrast or stained specimens (e.g. blood smears) to be viewed easily and quickly.
Beside the so-called direct bundles of rays, the indirect, i.e. the bundles of rays diffracted and scattered at
specimen details, are of major importance for imaging true to the object. The higher the portion of
indirect bundles of rays (aperture), the more realistic is the microscopic image according to ABBE.
To fully exploit the optical performance of the microscope, particularly that of the objective, condenser,
luminous-field diaphragm and aperture diaphragm should be set according to the rules of the KÖHLER
illumination principle. These fundamental rules of microscope adjustment are described in detail below in
Section 4.9.1 (3) "Transmitted-light brightfield according to KÖHLER" for the Axio Imager.
(2) Instrument
configuration
−
The equipment of all Axio Imager microscopes allows transmitted-light brightfield microscopy.
−
For the use of the achromatic-aplanatic universal condenser 0.9 H/0.8-0.9 DF, refer to Section
4.9.2 (4).
(3)
Setting transmitted-light brightfield according to KÖHLER
−
The microscope has been started up correctly as described in Section 3.
−
The microscope has been switched on.
•
Set the toggle switch for the halogen illuminators on the rear side of the instrument to transmitted
light.
•
Turn voltage control (4-114/
2
) on microscope base to adjust image brightness. If the transmitted-light
shutter is closed (indicator LED is not lighting), open it by means of button (4-114/
1
).
•
Place a high-contrast specimen on the mechanical stage.
•
Swivel in front lens of condenser (for objectives
≥
10x) and use the vertical control of the condenser
5
or 4-115/
3
) to move it up to the upper stop. The stop must have been set in such a manner
that the specimen is not touched by the condenser (for setting the stop of the vertical condenser drive,
refer to Section 4.9.1
(4)).
•
Swivel in 10x objective (yellow ring, also refer to Section 2.5) on nosepiece (4-114/
7
) and focus on the
specimen using the focusing drive (4-114/
4
).
•
Close luminous-field diaphragm (4-114/
3
) until it becomes visible (even if not in focus) in the field of
view (4-114/
A
).
•
Turn the vertical control of the condenser drive (4-114/
5
3
) to lower the condenser until the
edge of the luminous-field diaphragm appears in focus (4-114/
B
).
