100
Quantitative interference attachments
Surface roughness and topography are depicted
as interference fringes by the various
interference techniques. These are evaluated
similar to the way contour lines are interpreted
on maps. The measurement accuracy is up to
30 nm, the maximum height difference is about
30
µ
m. See special instructions.
Fibre-optic, light guides
Illumination with flexible fibre-optic light guides
with ball-jointed arms (VOLPI intralux 6000),
rotatable round the optical axis of the
objectives. Colour glass filter(s), slip-on iris
diaphragms, auxiliary lenses, polarization
device (polarizer and analyser).
Incident light polarization
Adjustment
Set the light source and diaphragms as for
incident light brightfield (page 90 and 95).
Reflector: BF or Smith, the Smith reflector is
better from a polarization optic point of view and
should be used for slight anisotropy (polari-
zation) (see Fig. 30).
Crossing the p olarizers
Imp ortant: The polarizers should be exactly
vertical or horizontal as a deviation of even 1
°
may lead to impaired extinction.
Setting the R/P p olarizer (29.1):
When combined with IC/P analyser (30.7)
When combined with 360 analyser (30.1)
Focus an isotropic specimen that fills out the
whole field of view, e.g. a mirror, open the
aperture diaphragm (65.12) and turn the analyser
(65.1) until the maximum extinction position can
be seen. For the IC/P analyser (30.5) the
λ
engraving must point downwards (compensator
inactive).
As for transmitted light (page 77) a particularly
precisely crossed position can be achieved with
a Bertrand lens or auxiliary telescope.
Polarizer with rotatable whole-wave comp en-
sator (29.9)
Set the analyser exactly at 0
°
or 90
°
.
Turn the whole-wave compensator (29.3) roughly
to the centre position.
Turn the polarizer until the object appears as
dark or as highly contrasted as possible, turn the
whole-wave compensator (29.4) until colour
contrast is obtained.
Filter system POL (p . 33 and ICR)
This does not need adjusting, as polarizer,
analyser and 45
°
flat glass reflector are
combined as a fixed unit.
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