OPERATION
ZEISS
Illumination and contrast techniques
Axio Observer
150
431004-7244-001
12/2016
5.12.3
Setting up differential interference contrast (DIC) for transmitted light
5.12.3.1
General operating principle
The transmitted light DIC technique is used to produce high-contrast, 3D images of transparent specimen
details.
Light which has been linearly polarized by a polarizer is split into two beams in a birefringent prism. These
two beams pass through adjoining regions of the specimen a small distance apart and experience
different path differences as a result of different refractive indices and specimen thicknesses. The two
beams are then recombined by a second birefringent prism and after passing through the analyzer have
the same direction of vibration. This allows the two beams to interfere in the intermediate image, with
the path differences being transformed into differences in intensity (gray scale).
5.12.3.2
Instrument equipment
−
Objectives offered for DIC equipment, e.g. EC Plan-Neofluar DIC.
−
DIC slider suitable for the objectives used
−
Condenser with turret disk equipped with DIC prisms (DIC I, DIC II, DIC III) or DIC condenser module
−
Polarizer, e.g. polarizer D with 2-position filter changer (only required where the condenser used does
not have a DIC prism with integrated polarizer).
−
Analyzer module Pol ACR P&C for transmitted light in the reflector turret or analyzer, e.g. fixed
analyzer slider or
±
30° analyzer slider (de SÉNARMONT)
5.12.3.3
Setting up transmitted light DIC
•
Select an objective suitable for DIC on the nosepiece. Insert the corresponding DIC slider (Fig. 152/
3
)
into the slot on the nosepiece. Ensure that the DIC slider clicks into position.
•
Select the appropriate DIC prism I, II or III on the condenser turret.
•
Insert the analyzer slider (Fig. 152/
4
) into the stand. Ensure that it clicks into position correctly.
(1)
Transmitted light DIC with fixed analyzer slider
•
Move the polarizer (Fig. 152/
1
) on the carrier for transmitted-light illumination into position. Ensure
that it clicks into position correctly.
•
Place the specimen onto the stage.
•
Configure the luminous-field diaphragm and aperture diaphragm on the condenser (Fig. 152/
2
) for
KÖHLER illumination.
•
Set the optimum contrast using the knurled screw on the DIC slider. Symmetrical adjustment of the
DIC slider around its center position allows specimen details to be viewed in 3D as if raised or lowered.
Summary of Contents for Axio Observer Series
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