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OPERATION
Axiolab 5
Illumination and contrast methods in transmitted light
ZEISS
05/2019
430037-7444-001
107
4.2.5.5
Circular polarization contrast with Axiolab for conoscopy
(1) Application
Unlike standard polarization contrast, circular polarization contrast does not show any dark (extinction)
positions that depend on the angle of rotation (azimuth) of the specimen relative to the polarizer or
analyzer. This means that when the stage is rotated, the image impression remains the same, as the
light/dark positions are omitted. With optical anisotropy, all transparent specimens display the
characteristic interference colors.
(2) Instrumentation
−
Strain-free objectives
−
Pol rotary stage
−
Circular polarizer D (no polarizers may be adapted on the condenser) including corresponding the
lambda/4 plate.
(3) Configuring the microscope
•
Configure the microscope as for transmitted light brightfield microscopy using the KÖHLER method
(see section 4.2.1).
•
Center the Pol rotary stage or objective (if this has not already been done – see section 3.1.7.5
or 3.1.7.6).
•
Initially, do
not
use a specimen for the further settings.
•
Swivel the analyzer into the beam path.
•
Swivel the lower part of the circular polarizer D (Fig. 4-16/
2
) into the beam path until it engages and
evaluate the extinction (darkening) of the field of view without the specimen at full light intensity.
If this is not optimal, align the analyzer as necessary.
•
Insert the respective 6x20mm slider with the lambda/4 plate (Fig. 4-16/
1
) as far as it will go into the
slot for compensators above the nosepiece.
•
Then swivel the upper part of the circular polarizer D (Fig. 4-16/
4
) into the beam path.
•
Rotate the lever of the lambda/4 plate of the circular polarizer D (Fig. 4-16/
3
) until extinction is
maximized (dark-gray field of view) (lever points 45° to the right).