Leica DM L, Инструкция по эксплуатации

Страница: 49 / 75

50
The dark stripe should be in the centre of the
brighter circular area (Fig. 36). If not, proceed as
follows: push in the left-hand centering key
(10.3b) on the back of the condenser until it
clicks into position and rotate it until the stripe is
in the centre of the circle. The right-hand key is
not required. However, make sure that the left-
hand centering screw for light rings is not
turned too far inwards or it may obstruct the
movement of the prism with the left-hand key.
Objectives for ICT
Transmitted light interference contrast is
possible with objectives that have the letter
indicating the pupil position, e.g. D, in the first
line of engraving (p. 27), and which are listed as
suitable for ICT on the optics data sheet.
A condenser prism, e.g. K
2
, must also be
available for the objective.
Choice of prisms
Insert the objective prism slide (32.8) into the
tube slit (34.6). The code letter, e.g. D, must
coincide with the code letter in the objective
engraving (
→
p. 27).
Select the condenser-side prism (34.2) that
corresponds to the magnification of the
objective used, e.g. pos. 20/40 for 20x and 40x
objectives,
→
note on p. 15.
Swing in the condenser top 0.90 S1 (or 1.40 OIL).
Set Koehler illumination exactly (
→
p. 37). This
is made easier by temporarily focusing a stained
specimen or the edge of the coverglass.
Setting ICT contrast
Carefully adjust the objective prism slide with
the adjustment screw (34.6) to obtain an
optimum image. Also adjust the contrast with
the aperture diaphragm (34.3). Particularly sen-
sitive setting is possible with the
λ
/4
compensator (32.4), which is inserted into the
holder under the condenser (34.4) and rotated
(objective prism roughly at the centre position).
Optimum contrast for specimens with parallel
structures can be obtained by rotating the stage
(34.7).
λ
compensator
Colour contrast: Insert the
λ
compensator (32.2)
above the polarizer (34.4 or 33.6a) and rotate.
Preparation
ICT gives best results for unstained, relatively
thin,
non -birefringent specimens. Interpretation
of birefringent specimens can be extremely
difficult, if not impossible. It may be helpful to
rotate the specimen to an optimum azimuth
position.
Attention:
Specimen slides, coverglasses and embedding
resins of birefringent material may not be used.
!