Leica DMR Bedienungsanleitung Seite 66

Disengage the analyser (54.3), tube lens 1.6x
(54.11) and Bertrand lens (54.2). Greatly narrow
the aperture diaphragm (54.9). Insert the two
objective centering keys above the objective
you want to centre (38.5). Focus the object.
There are two similar methods of objective
centration:
Method I (Fig. 46a)
Rotate the stage and note the point on the
specimen that remains stationary. This point
corresponds to the mechanical axis of rotation
of the stage.
Now move this prominent point of the specimen
to the centre of the crosslines with the two
centering keys. Rotate the stage and fine-adjust
the centration if necessary.
Fig. 46a
Centration method I
66
Fig. 46b
Centration method II
M
a
Method II (Fig. 46b)
Move the prominent point on the specimen (46a)
to the centre of the crosslines M. Rotate the
stage until the point on the specimen is furthest
away from the centre of the crosslines M
(position A, Fig. 46b). Point A (= maximum
distance of the specimen point from the centre)
may even be outside the field of view. Turning
the centering keys, adjust the image until the
specimen point A is midway (= pos. B) between
pos. A and the centre of the crosslines M (46c).
Move point A to M and check that A stays at M
when the stage is rotated (46d). Repeat the
centering process if necessary.
Each objective must be centered separately. If
an objective is screwed out of the nosepiece,
e.g. for cleaning, and screwed back in the same
place, its centration is more or less retained. If
the stage height is altered by a few centimetres
with the coarse drive or stage clamp (e.g. for
specimens of different thickness) the fine
centration may be slightly lost for all objectives.
M
B
A A
b
M M
B
A
c d