Olympus bx40 - Page 21

Е:
|
Aperture
Iris
Diaphragm
(Figs,
54,
55)
|
diaphragm
image
70-
80%
*
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.
* Since the contrast of microscopic specimens is ordinarily low, setting
the
condenser
aperture
iris
diaphragm
to
70~80%
of
the
NA.
of
the
objective
in
use
is
usually
recommended.
When
necessary,
adjust
this
Objective pupil
|
fatio
by
removing
the
eyepiece
and
peeking
into
the
eyepiece
sleeve
to see the image shown in Fig. 54.
[ Using the Numerical Aperture Scale ]
Sap
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
listes vasa NA. scale
SIOHLNO9
3HL
ONISN
В
Fig. 55
Compatibility of Objectives and Condensers
Condenser
Objective Achromat/ Swing-out Ultra-low
magnification Αμ aplanat achromat magnification
U-AC
U-AAC U-SC U-ULC
1.25X
2X Usable by moving Usable
front element out of
ΑΧ Usable to FN22 the light path”?
o | Front element
10-60X
Usable Ussble。 En.
100X 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.
*? Although slightly inadequate NA results in @ 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