Leica DM2500, Manual

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67
11. Trouble Shooting
Problem
Fluorescence: The lamp does not illuminate im-
mediately upon being switched on.
Brightfield
The specimen can not be brought into focus.
Darkfield
No definite DF contrast is possible.
The image is unevenly or not uniformly illumi-
nated.
Undesirable stray light.
Cause/Remedy
The external power supply must be switched
on repeatedly.
Hot Hg lamps should cool down before
switching on again.
Use the correct immersion medium.
Lay the specimen with the cover glass toward
the top.
Make sure that the cover glass thickness is
correct and that it suits the indication on the
objective.
Be sure that a DF objective is being used.
The objective aperture setting is too high
(maximum 0.75/1.10). If necessary, reduce the
objective aperture using the iris diaphragm on
the objective.
Check the condenser centering.
Open the aperture diaphragm completely.
The magnification is too weak. Use a higher
magnification.
Clean the specimen and neighboring lenses
(
→
p 71).