Axio Imager 2
OPERATION
ZEISS
Illumination and contrast methods
01/2016
430000-7544-001
169
4.12.4
Setting transmitted-light differential interference contrast (DIC)
(1)
General principle
The transmitted-light DIC method is an alternative contrast method to polarization which allows high-
contrast, 3D presentation of transparent specimen details.
The light is linearly polarized by a polarizer and split into two partial beams by a birefringent prism. The
beams pass through two adjacent places of the specimen resulting in path differences caused by
differences in the refractive index and thickness of the specimen. The two partial beams are then
recombined in a second birefringent prism and, after passing through the analyzer, have the same
vibration direction. Thus, both partial beams can interfere with each other in the intermediate image; the
different path differences are converted into different gray values (intensities). A compensator
λ
(full-
wave plate) then converts the gray values to colors.
(2)
Instrument equipment
−
Objectives supplied with the DIC equipment, e.g. Plan-Neofluar objectives
−
Objective nosepiece with slot for DIC slider, matching the objectives used
or
Motorized four-position modulator turret in combination with analyzer module DIC ACR shiftfree for
transmitted light
−
Condenser with turret disk containing DIC prisms (DIC I, DIC II, DIC III)
−
Analyzer module D DIC P&C (424921-9901-000) in reflector turret. Only this module may be used on
the Axio Imager 2 as it provides a homogeneous field of view in combination with the special
condenser modules I, II and III.
−
Preferably a rotary mechanical stage
(3)
Adjusting the transmitted-light DIC with DIC slider and DIC prism in the condenser turret
•
On the nosepiece, swivel the objective (Fig. 197/
4
) suitable for DIC into the light path.
Push the corresponding DIC slider (Fig. 197/
1
) into the slot of the respective objective position. Make
sure the DIC slider clicks in.
•
On the reflector turret (Fig. 197/
3
), swivel in the analyzer module D DIC (Fig. 197/
8
).
•
Swivel in the suitable DIC prism I, II or III (digit label on turret disk of condenser (Fig. 197/
6
)).
•
Adjust the luminous-field diaphragm and aperture diaphragm (Fig. 197/
5
) in accordance with the rules
of KÖHLER illumination.
•
Turn knurled screw (Fig. 197/
2
) on DIC slider (Fig. 197/
1
) to obtain optimum contrast. When adjusting
the DIC slider symmetrically around its mid-position, the specimen details can be imaged in such a way
that they appear three-dimensionally, as if they were raised or recessed.
•
If desired, the compensator
λ
7
) can be inserted into the slot for the analyzer slider above the
nosepiece to obtain colored DIC contrast.
For 63x objectives, in addition to the DIC sliders HR (High Resolution), another type - HC (High Contrast) -
is available which should be used depending on the type of specimen and examination to be performed.
