OPERATION
Axioscope 5/7/Vario
Illumination and contrast methods in transmitted light …
ZEISS
03/2018
430035-7344-001
95
4.2.4
Setting up transmitted light differential interference contrast (DIC)microscopy
(1) General principle of operation
The transmitted light DIC method allows for a high-contrast vivid display of transparent sample details.
The light is linearly polarized by a polarizer and is separated into two beams in a birefringent prism. The
two beams penetrate two parts of the sample which are closely separated. They experience different path
differences due to the different refractive indices or different sample thickness. Both beams are then
reunited in a second double refractive prism and have after passing the analyzer the same polarization.
Therefore both beams can interfere in the intermediate image and the path differences are thus
converted into intensity differences represented by a gray scale. A compensator or
λ
-plate may be used
for a consecutive conversion of the gray scale in a color scale.
(2) Instrumentation
−
Objectives equipped with DIC fixtures, e.g. EC-Plan-Neofluar objectives
−
Nosepiece with slot for DIC slider
−
DIC slider, compatible with the objectives in use
−
Condenser with turret disk containing DIC prisms (e.g. condenser, achromatic-aplanatic 0.9 H D
PhC DIC)
−
Analyzer module ACR P&C for transmitted light in the reflector turret/slider or analyzer slider D/A
fixed or rotatable in conjunction with a mounted intermediate plate for analyzer slider 12x46
−
Rotatable mechanical stage, if necessary
(3) Setting transmitted light DIC
•
Put the DIC compatible objective (
3
) in place on the nosepiece. Slide the according DIC slider
1
) into the slit of the appropriate objective position. Make sure that the slider engages firmly.
•
Swing in the analyzer module (
6
) on the reflector turret (
7
) (or slide the analyzer slider
into the intermediate plate for analyzer sliders).
•
Swing in the DIC prism (position
DIC
on the condenser) (
4
).
•
Adjust field diaphragm and aperture diaphragm according to the KÖHLER method.
•
Adjust the optimal contrast on the DIC slider (
1
) with the knurled screw (
2
).
Symmetrical adjustment of the DIC slider along its middle position lets the sample details appear as if
they were elevated or deepened.
•
If desired, the compensator
λ
5
) can be put into the opening above the nosepiece in order to
create a chromatic DIC contrast.
NOTE
The DIC method functions with polarized light. It is disturbed when birefringent elements, e.g.
foils, are put between polarizer and analyzer, as is sometimes done when doing a histological
incision. The same situation occurs with Petri dishes or specimen holders which have a plastic
base. In these cases we recommend using PlasDIC.
