Olympus bx40 - Page 40

Aperture iris
diaphragm
Objective pupil |
Fig. 54
(2)
1
lara
tasa
ας
«ελ
N.A.
scale
i
PM
|
Fig. 55
(Figs. 54, 55) |
¢
The
aperture
iris
diaphragm
determines
the
numerical
aperture
of
the
illumination
system.
Matching
the
numerical
aperture
of
the
illumination
system
with
that
of
the
objective
provides
better
image
resolution
and
contrast,
and
also
increases
the
depth
of
focus.
| Aperture Iris Diaphragm
* Since the contrast of microscopic specimens is ordinarily low, setting
the condenser aperture iris diaphragm to 70~80% of the N.A. of the
objective in use is usually recommended. When necessary, adjust this
ratio by removing the eyepiece and peeking into the eyepiece sleeve
to see the image shown in Fig. 54.
E Using the Numerical Aperture Scale Al
Set the condenser numerical aperture to about 80% of the NA value
@ indicated on the objective. (Fig. 55)
Example: With the Plan 40X (NA 0.65), set the scale to 0.65 x 0.8
= 0.5.
Compatibility of Objectives and Condensers
ns
E
q
386
A
DE
ως
Usable
by
moving
Usable
5 front element out of
Usable
to
FN22
the
light
path*?
Usable Usable eme
NA not fully
adequate*'
*' When using the U-SC swing-out achromat condenser together with the 2X or 4X
objective, fully open the condenser aperture and use the field iris diaphragm in the
base as aperture diaphram.
*2 Although slightly inadequate NA results in a somewhat darker field of view with a
100X objective, the combination is usable.
© To obtain better illumination, use of the U-ULC is recommended in photomicrography
when using the 2X or 4X objective.
Table 4
A-18
A0