Leica DM R Serie Mode D'emploi page 89

Preparation errors
Possible sources of error if ICT image is
unsatisfactory :
Embedding medium, specimen slide (Petri dish)
or object (e.g. crystals, fibres) are of birefringent
material. The phase shifts caused by bire-
fringence disturb the inter-ference contrast
image. This can sometimes be remedied by
rotating the specimen.
The specimen is too thick or too thin.
Specimen slide or coverglass are too thick
or the coverglass is missing (except for
HC PL FLUOTAR 5x/0.12 and 10x/0.25, which can
be used either with or without a coverglass).
The difference in the refractive indices of the
specimen and the embedding medium is too
small (this often happens when uncovered
specimens are observed with an immersion
objective). Inhomogeneous mounting medium.
Errors in instrumentation
Polarizers not engaged, or rotated too far out of
the crossed position or, though crossed, turned
out of the zero positions.
Polarizer has been damaged by powerful light
sources. Check this by holding the polarizer
against a window or light source. Damaged
polarizers then
colouring.
The IC prisms in the condenser are in the wrong
position or upside down. This is checked by
combining an IC prism with all available
objectives and seeing if the interference
contrast image is optimal at corresponding
magnifications of the objective and the
condenser.
Condenser top in wrong position.
Wrong condenser top (only 0.90 S1 or P 0.90 S1
or P 1.40 OIL may be used).
Koehler illumination not set (image of field
diaphragm in the specimen plane).
Aperture diaphragm too wide or too narrow.
Dirty optics or polarizer.
Dust p rotection: Turn the condenser prism out of
the light path if it is not being used for a long
time.
For specimens with parallel texture: specimen is
in wrong azimuthal position (remedy: rotate
specimen with stage 60.2; 54.15).
The following
fluorescence, brightfield, darkfield, polarized
light and interference contrast techniques.
show distinctly
description applies
uneven
for
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