ZEISS OPERATION Axio Imager 2
Illumination and contrast methods
178 430000-7544-001 01/2016
4.12.5.4 Transmitted-light circular polarization contrast
(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 the image will always look the same when the stage is rotated, as there are no
bright and dark positions. With optical anisotropy, all transparent specimens show the interference colors
that are characteristic to them.
(2) Instrument equipment
− Phototube Pol
− Achromatic-aplanatic universal condenser Pol
− Strain-free objectives
− Rotary stage Pol
− Polarizer D (rotatable or fixed)
− Circular polarization equipment D, ACR, with λ/4 plate, rotatable for transmitted light, including
reflector module λ/4, ACR, P&C (427703-9901-000)
− Analyzer slider
(3) Setting the microscope
• Set the microscope as for transmitted-light brightfield according to KÖHLER (see Section 4.12.1 (3)).
• Center rotary stage Pol and objectives (if not yet completed - see Sections 3.36.3, 3.36.4).
• For the further settings, do not use a specimen initially.
• Push the analyzer slider (Fig. 202/6) into the light path.
• Install the circular polarizer D (see Section 3.38), and insert reflector module λ/4, ACR, P&C
(Fig. 202/5) in the reflector turret.
• Swivel the bottom part of the circular polarizer D (Fig. 202/3) into the light path up to the click stop
and, at full light intensity, assess the extinction (darkening) of the field of view without specimen.
If the extinction is not optimal, correct the position of the vibration direction by slightly and sensitively
turning the polarizer mount (use the adjusting slots (Fig. 202/4) on the bottom of the polarizer for this)
until maximum extinction is obtained. Normally, however, this will not be necessary, as the position of
the vibration direction of the polarizer is factory-adjusted.
• Then, swivel the top part of the circular polarizer D (Fig. 202/2) into the light path.
• Rotate the lever of the λ/4 plate of the circular polarizer D (Fig. 202/1) until maximum extinction is
obtained (dark-gray field of view) (lever points 45° to the right).
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