Illumination And Contrasting Techniques; Setting Of Transmitted-Light Brightfield According To Köhler - Zeiss Axioskop 2 Manual

3.3

Illumination and contrasting techniques

3.3.1 Setting of transmitted-light brightfield according to KÖHLER
(1) General principle
Transmitted-light brightfield microscopy is the most usual of all the optical techniques, since it allows the
easy and fast viewing of high-contrast or stained specimens (e.g. blood smears).
For as true-to-object imaging as possible, 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 portion of indirect rays (aperture), the more realistic the microscope image will be, according
to ABBE's rule.
To utilize the entire optical performance of the microscope, especially of the objective, the condenser,
the luminous-field diaphragm and the aperture diaphragm should be set in accordance with the rules for
KÖHLER illumination. These basic rules of microscope setting are described in detail in section 3.3.1 (3)
"Transmitted-light brightfield settings according to KÖHLER on the manual Axioskop 2".
(2) Transmitted-light brightfield equipment of the manual Axioskop 2
Each manual Axioskop 2 configuration permits performance of the transmitted-light brightfield
technique.
(3) Transmitted-light brightfield settings according to KÖHLER on the manual Axioskop 2
− The manual Axioskop 2 has been set up as described in chapter 2.
− The manual Axioskop 2 has been switched on.
• Set the image brightness via voltage control (3-16/1) on the microscope stand.
• Place a high-contrast specimen on the specimen holder of the mechanical stage.
• Swing in front lens of the universal condenser (3-16/3) (for objectives ≥ 10x) and use drive for height
adjustment (3-17/2) to move condenser to the upper stop. The stop must be set in such a way that
the specimen is not touched by the condenser (for setting of condenser stop, see section 3.3.1 (4)).
• Switch turret disk of condenser (if available) to position H for brightfield via the knurled ring. If no
separate brightfield position is available, the turret position (I, II, or III) can be chosen which does not
contain a DIC prism. If all three positions are equipped with DIC prisms, switch off the analyzer in the
reflector turret.
One turret position of the universal condenser should remain empty for highest demands in
transmitted-light brightfield.
3-24
OPERATION

Illumination and contrasting techniques

Axioskop 2 / Axioskop 2
B 40-075 e
MOT
06/98