40
An aperture diaphragm in the
objective
(Fig.
25.4) is normally fully opened. The reduction in
image brightness caused by stopping down
results in:
Greater depth of field
Less coverglass sensitivity (p. 27)
Suitability for darkfield (p. 44)
Change in contrast
Objective magnifications 1.6x and 2.5x*
Lowest magnification, see also p. 32.
Condensers CL/PH or CLP/PH and UCL or UCLP:
(
→
p. 13): objective
4x.
With slot-in diffusing
screen in slide 2.5x, but not for polarized light.
Condensers UCL/UCLP with auxiliary lens 2.5x
(9.7):
2.5x
objective.
First
disengage
the lens for the 2.5x objective
(9.7) (switch to PH or BF position), set Koehler
illumination
→
p. 37 (Fig. 29) with 4x or 10x
objective.
Engage lens for 2.5x objective with condenser
disc (28.15) (not possible with CL/PH or CLP/PH
condenser).
Open the aperture diaphragm (28.14) as far as
the stop.
Narrow the field diaphragm (28.10). In case of
arc-shaped vignetting,
center the lens:
insert
both centering keys (9.5) into the UCL or UCLP
condenser (9.3; 28.3) at an angle from the back
and adjust until the
asymmetrical
vignetting
disappears. Remove the centering keys and
open the field diaphragm.
Operation of transmitted light
The lens can only be used up to an objective
magnification of max. 20x. Exact Koehler
illumination (
→
p. 37) can no longer be
obtained!
Magnifications of
1.6x
and
2.5x
are also possible
with the CL/PH or CLP/PH and UCL or UCLP
condensers (
→
p. 13) if the condenser is
removed completely. The field diaphragm then
takes over the function of the aperture
diaphragm.
Condenser tops*
UCA/P condenser (Fig. 10) and achr. apl. 0.9 (P):
from
1.6x
objective (the slot-in diffusing screen
(see p. 14) must be used on the condenser achr.
apl. 0.9 (P), max. eyepiece fov 22).
The condenser top (10.1; 12) is disengaged for
objective magnifications 1.6x and 5x, and
engaged from 10x upwards. The functions of the
aperture and field diaphragms are then
cyclically exchanged.
The oil immersion condenser top can be used to
enhance resolution with objectives of 1.0
aperture or higher, condenser top
S 15
for long
free working distances, e.g. for heating stages.
When thick glass windows are used, the total
working distance (distance between the
condenser top and the specimen plane)
increases by approx.
1
/
3
of the glass thickness.
Condenser tops with the engraving
P
are
required for quantitative polarization
microscopy as they are especially low in strain.
Содержание DM L
Страница 1: ...Leica DM L Instructions...