OPERATION
Axiolab 5
Illumination and contrast methods in transmitted light
ZEISS
05/2019
430037-7444-001
91
4.2.4.2
Determination of the polarization direction n
γ
’
(1) Application
The determination of the polarization direction of n
γ
or n
γ
'
respectively (polarization direction with the
absolute or relative largest index of refraction) and n
α
or n
α
'
respectively (polarization direction with the
absolute or relative smallest index of refraction) relative to the morphological directions, e.g. of crystal
surfaces, crystal needles or fibers, provide an important signature of the material. This method is also
used in the diagnosis of bio-crystals (e.g. gout and pseudo-gout).
Fig. 4-8
Determining the polarization direction n
γ
'
using a synthetic fiber as an example
(2) Instrumentation
−
Eyepiece with crossline reticle
−
Strain-free objectives
−
Pol rotary stage (Fig. 4-7/
1
)
−
Polarizer D (rotatable or fixed)
−
Screw-in fixed analyzer slider D or lambda compensator or lambda/4 compensator combined with
analyzer (in Axiolab 5 tubes)
−
Pol adjustment tool sample for polarization microscope (453679-0000-000)
(3) Configuring the microscope
•
Adjust the microscope as described in section 4.2.1 (3) for transmitted light brightfield microscopy.
Make sure the inter-pupillary distance is adjusted correctly on the binocular tube (see section 4.1.1).
•
Center the Pol rotary stage (Fig. 4-7/
1
) and objectives (see sections 3.1.7.5 and 3.1.7.6).
•
Swivel the polarizer (Fig. 4-7/
3
) into the beam path and, if it is rotatable, position it at 0°.
•
Insert the analyzer slider (Fig. 4-7/
2
) into the slot for compensators or in the intermediate plate (if tube
does not already have an analyzer). The field of view will appear dark due to the crossed polarizers. If
not, align the analyzer in the tube or the intermediate plate.
•
Place the Pol adjustment tool sample on the microscope stage and rotate it until the sample appears
dark.
