Axioskop 2
plus
OPERATION
Axioskop 2
mot plus
Illumination and contrasting techniques
Carl Zeiss
B 40-075 e 02/01
3-31
3.3.4
Setting of transmitted-light polarization
3.3.4.1
Detection of birefringence
(1) Application
The transmitted-light polarization technique is used for specimens which change the polarization
condition of light. These are called birefringent, e.g. crystals, minerals or polymers. If these birefringent
substances are viewed between crossed polarizers (polarizer
⊥
analyzer), they are brightened while their
surrounding remains dark.
Birefringent substances are recognized by the fact that they feature 4 bright and 4 dark positions
between crossed polarizers when the microscope stage is turned around 360°. Interference colors
ranging from gray (mostly with biological objects) to white, yellow, red and blue occur as a function of
birefringence, thickness and orientation of the object. These interference colors can be of the 1
st
or a
higher order.
(2) Axioskop
2
plus
and Axio-
skop 2
mot plus
configuration
−
Objectives suitable for polarization
−
Rotary mechanical stage 75x50/240° R
−
SENARMONT DIC polarizer or polarizer D (rotary
or fixed), unless a polarizer is integrated in the
condenser
−
Analyzer module D in the reflector turret
(3) Setting of Axioskop
2
plus
and
Axioskop 2
mot plus
•
Set the microscope as for transmitted-light
brightfield according to KÖHLER (see section
3.3.1 (3)).
•
Center rotary mechanical stage (3-22/
2
) (see
section 2.2.9 (2)).
•
1
) in beam path and
position it to 0°, provided that a rotary polarizer
is used.
•
Swing in analyzer module on reflector turret (3-22/
). The field of view now appears dark on account
of the crossed polarizers.
•
Bring examination object in the field of view and turn it around 240° along with the rotary stage.
Birefringent (anisotropic) objects now normally display the aforesaid color and intensity changes
occurring during rotation between crossed polarizers. However, optically anisotropic substances can
also remain dark if an isotropic direction, e.g. of optically uniaxial or biaxial crystals, is oriented parallel
to the observation direction.
1
0
2
0
30
40
50
6
0
7
0
80
90
10
0
Fig. 3-22
Components for transmitted-light
polarization on the Axioskop 2
plus
