Linear Measurements - Leica DMLS Bedienungsanleitung

Unblock the incident light path (31.9), switch off
transmitted light or cover with slide (25.5) (push
into the stage from the front: 31.11), focus the
specimen.
Disengage the BG 38 filter (31.8) if there is no
disturbing red background. Always engage the
filter for photography, however.
Collector setting
Halogen, Hg and Xe lamps:
Adjust the collector (31.6) until the object is
homogeneously illuminated, optimize adjust-
ment if possible.
Possible errors
Weak fluorescence, weak image intensity due to:
Incorrectly stored, too old or faded specimens;
fast specimen fading (e. g. with FITC); inspecific
filter combination, numerical aperture of objec-
tives too low; eyepiece magnification too high;
spent lamp; room too bright. Trinocular tube:
wrong beamsplitter setting (37.4), secondary
light due to reflection at the condenser.
Low contrast image due to:
Excitation bandwidth too great; inspecific
staining; fluorescing inclusion medium; auto-
fluorescence of the objective or immersion oil.
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Linear measurements

The following are required for linear measure-
ments:
– Graticule with scale division in eyepiece
(Fig. 33) HC FSA 25 PE tube with diapositive
overlay device or a digital linear measuring
eyepiece.
– Stage micrometer for calibration.
Micrometer value
The micrometer value of the objective-eyepiece
combination used must be known before the
measurement, i. e. the distance in the specimen
that corresponds to the length of a division on
the graticule used.
Calibration:
Align the stage micrometer and the graticule
parallel to each other by rotating the eyepiece
and adjust the zero marks of both scales to
exactly the same height (Fig. 33).
Read how many scale divisions of the stage
micrometer correspond to how many on the
microscope scale (graticule) and divide the two
values. This gives the micrometer value for the
total magnification that has just been used.