Phase Contrast; Camera - Leica DMil Mode D'emploi

8. Operation

8.4 Phase contrast

Phase contrast is for contrasting unstained spec-
imens.
• Adjust the condenser height.
• Insert the phase contrast light ring slide into
the fixture (Fig. 26.1).
(Caution: There are different sliders for the
condensers!)
• Swing the phase contrast objective (engraved
PH) with the weakest magnification into place
using the objective nosepiece.
• Open the aperture diaphragm (Fig. 26.2).
• Bring the specimen into focus using the coarse
and fine adjustment. If you have difficulties
finding the specimen plane: Stop down the ap-
erture diaphragm temporarily or use a stained
specimen. To do so, move slider into the BF
position or remove light ring slider. Open the
aperture diaphragm.
• Use the light ring of the light ring slide that cor-
responds to the magnification (5, 10, 20 or 40).
The phase contrast light ring slide is encoded.
As soon as the slider is taken out of the bright
field position (available opening) and engaged
in a phase contrast position (any light ring), the
brightness increases. Conversely, switching
from phase contrast to bright field decreases the
brightness.
Note:
The light rings do not need to be centered. The
superimposition of light rings and phase rings is
adjusted at the factory.
34
Possible faults
Specimen too thick, too thin or too brightly
stained; refractive indexes of the mounting me-
dium and specimen are identical, so that there is
no phase jump.
!
Caution!
Cover slip placed in a wedge-shaped position, so
that the centering of the light and phase ring is
no longer effective.
• Incorrect light ring.
• Aperture diaphragm not open.
• Condenser in incorrect height position. Slide
the condenser further up or down to obtain op-
timum phase contrast.
• Incorrect light ring slide (There is one slide
each for the S80/0.30 and S40/0.45 condenser.).
• Optics dirty.

8.5 Camera

For detailed information how to use the Camera,
please check the user manual on the LAS CD.
Fig. 26 Phase Contrast
1 Phase contrast slider
2 Aperture diaphragm
2
1