OPERATION
Carl Zeiss Illumination and contrast methods Axio Imager
158 430000-7344-001 M70-2-0020 e 06/2009
(3) Setting the microscope
The microscope has been prepared as described in Section
4.9.5.1 (3).
• Rotate the rotary stage Pol with the specimen, e.g. a synthetic fiber, until the specimen appears as
dark as possible. In this position, the fiber extends parallel to one of the two directions of the
crosslines reticle.
• Next, turn on the rotary stage Pol by 45°, until the longitudinal axis of the fiber is oriented NORTH-
EAST (NE) – SOUTH-WEST (SW) (Fig.
4-123). In this position, the specimen shows the maximum
brightness (diagonal position) and may appear in any color.
• Push in the full-wave compensator λ.
Like the specimen, the compensator λ is a birefringent object, though one with a defined path difference
of 550 nm and the principal vibration direction n
γ
definitely oriented in NE-SW direction
By moving compensator λ into the light path, the specimen changes its color. The kind of color change
depends on the orientation of the specimen (NE-SW or NW-SE).
The changes in color are based on optical interference. The interference colors (path differences) in both
diagonal positions (NE-SW and NW-SE) of the specimen must be compared in this connection.
The path difference results from the superposition (interference) of the vibration direction of the
specimen with the vibration direction of the compensator λ.
The greater path difference occurs, if the vibration direction of the specimen with the absolutely or
relatively highest refractive index (n
γ
or n
γ'
) is parallel to the principal vibration direction of
compensator λ. The specimen will then appear, for instance, greenish-blue (
4-123/2).
The smallest path difference occurs, if the vibration direction of the specimen with the absolutely or
relatively lowest refractive index (n
α
or n
α'
) is perpendicular to the vibration direction of the
compensator λ. The specimen will then appear, for instance, in yellow (
4-123/3).
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