OPERATION
Axioscope 5/7/Vario
Illumination and contrast methods in transmitted light …
ZEISS
03/2018
430035-7344-001
111
If the positions of the section are less favorable, i.e. the center of the cross of optically uniaxial or the
isogyre of optically biaxial specimens is outside the objective pupil, the optical character can be assessed
as follows:
•
If the black isogyres are
straight
and run (related to the reticle) parallel through the pupil, the
specimen is
optically uniaxial
.
•
If the black isogyres are
curved lines
, traveling across the pupil on a circular path, the specimen is
optically biaxial
.
NOTE
Axial figures can often be better represented with circular polarization. In particular, the axial
angle of optically biaxial specimens (more or less the space between isogyres) can be
determined more precisely and with much less ambiguity. The optical character can also be
determined by inserting the
λ
compensator (6x20 mm) into the compensator slot.