Olympus VANOX-T - Page 15

@
Opening of
the aperture
siaphraar
Objectiva
exi pupil
Fig. 14
70-80%
3020%
Fig. 15
Field of view
d iris diaphragm
9
10.
Adjustment of the field and aperture iris diaphragms
1) Aperture iris diaphragm © (Fig, 14)
+ In order to achieve optimum objective performance, the opening of
the aperture iris diaphragm should be matched to the numerical
aperture of the objective in use.
It is often preferable, however, to stop down the aperture dia
phragm slightly more than indicated by the objective N.A., since
‘microscope objects are generally low in contrast. (This will result
in better image contrast, increased depth of focus and a flatter
field.)
*
Repeat this adjustment each time the objective is changed.
+ After completing focus adjustment, remove one of the eyapieces
from the observation tube.
Looking into the empty eyepiace tube, stop down the iris dia
phragm so that the image of the iris diaphragm can be seen in the
‘objective pupil as shown in Fig, 15.
© Generally, darktield observation requires the maximum opening of
the aperture diaphragm. That, however. varies, depending upon the
specimen conditions for a better darkfield image with less glare,
+ In caso of darkfieid observation, the objective exit pupil is not
visible distinctly even by removal of the eyepiece; therefore, it is
recommended to adjust the opening of the iris diaphragm while
looking at the image of a specimen until you can obtain optimum
image contrast and definition with minimum glares.
2) Field iris diaphragm @ (Fig. 14)
The field iis diaphragm controls the diameter of the ray bundle
impinging on the specimen surface and therefore, by stopping
down the field diaphragm until itis slightly larger than the field
view, it will reduce stray light, which in turn increases image de
finition and contast
Light path selection
1) Vertical iluminator AHZ.MA;
In case of reflected light, turn the half-mirror knob (D to posi
rion
ぞ
in
case
of
transmitted
light,
turn
it
10
position
È.
(Fig.
16)
This light path selection requires the corresponding operation of
the mirror control knob at the microscope base,