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V.
OPTICAL SYSTEM
The
optical
system
of
the Series BH is d ivided
into
five sections: Objectives, observation
tubes, eyepieces, illumination and
photomicrographic
equipment. The
fol
lowing
is
the
brief-
ing of the objectives, eyepieces and illumination equipment.
1.
Object
ives
A
.
T
ypes
o
Achromat:
Literally color-free. The
achromat passes white light without separating it
into
its dif-
ferent color components. An image formed
by
an
achromat
wil
l
not be surrounded by
color fringes.
Recommended
for
general
use.
0
Fluorite (FI) (or semi-apochromat)
:
The name "fluorite" is derived from the mineral used
in lens
manufacture.
lt
makes
possible the
attainment
of a high order of
correction
for two colors chromatically and
two colors
spherically, and possesses excellent resolution, suited for photomicro-
graphy. as well as for bacteria and blood tests,
chromosome
examination, etc.
o
Apochromat (Apo):
An objective corrected
chromatically
for
three colors
and spherically for two
colors.
These corrections
are superior to those of the achromatic series of
lenses.
Field
curvature
is
still present. For research use.
o
Plan
Achromat (Plan):
Chromatic aberration
is
corrected for two
colors,
hence the other
colors
of the secon-
dary spectrum are
not
brought to the same focus. This objective is capable of
produc-
ing
a
flat image
to the edge
of the field.
lt is
therefore invaluable for the visual obser-
vation and photomicrography of flat
objects
such as stained smears and sections.
o
Plan Apochromat (Plan
Apo)
:
Capable of producing
a
flat image to the edge
of
the f ield, excellent resolution.
Free
of field curvature.
Chromatic
aberration is
corrected
for three colors, and spherical
aberration corrected for
two colors. Highest
class suitable for research
use.
B.
How
t
o Use
o
Immersion
Objective (engraved "HI" for homogeneous immersion)
To
utilize the full numerical aperture
of
an
immersion objective,
the objective, speci-
men and
condenser
are immersed
in
an
immersion liquid.
(
1)
Focus
on
the specimen with a
low
power
objective.
(2)
Put a drop of immersion
oil on
both
the
specimen and the objective front
lens.
(3)
Turn the
revolving nosepiece
to bring the immersion
objective
into
the
light
path,
and focus with the fine adjustment
knob.
NOTE:
Care should be
taken
to
prevent
oil
bubbles from
forming
in
the
oil
film
between
condenser.
specimen slide and
objective.
(4)
After
use,
carefully
wipe
off the
immersion
oil
deposited
on the
lens
surfaces
with
gauze mo istened with xy lene.
Never
leave oil on the lens surfaces after
use
as
oil
remnan
ts
w
il
l
seriously impair
the
performance of the
lens
systems.
0
Cover Glass
The cover glass is placed
over
the
object.
Olympus
objectives
with an engraving "0.
17"
are
corrected
for use
of
cover glasses
of 0.17mm
thickness (No. 1
%).
It
is
essential
to
use
only
No.
1
Y,
cover
glasses with dry
objectives
of N.A.
0.7
and higher
which
are not
equipped with a correction
collar.
8
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