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Purchase
planning ideas
Microscopes For Young Minds
Corporate Buyers
A good microscope is a lifetime
investment.
Are you intending to buy
your first
microscope, or planning
the purchase of
microscope equipment for
a college or
curriculum? This page is
intended to
provide concise information
about
the microscope. The definitions
of
a number of terms frequently
used in
microscopy are listed in
alphabetical
order in the
.
Section through
a bellflower
Reflected light, stereomicroscope
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What is the difference between compound
and stereoscopic observation?
Eye of the Roman snail,
stained thin
section Transmitted light
microscope |
Monocular or binocular observation
is
possible with every microscope.
Only the
stereomicroscope calls for
binocular
vision, although not every
binocular micro-
scope is a stereomicroscope.
The stereo-
microscope features two
separate optical
systems and two objectives
(objective
pairs).
A regular microscope
uses only one
objective at a time, although
different ones
are available on the objective
turret.
The image of the specimen
is taken by
one objective, magnified,
and projected
into the intermediate image
plane
approximately 10 mm below
the tube edge.
The intermediate image at
this site is
observed through the eyepiece,
which has
the effect of enlargement
by a magnifier.
Monocular observation uses
one eyepiece,
binocular observation two.
In a regular microscope with
binocular tube
the image projected by one
objective is
relayed to two eyepieces
by means of
prisms or mirrors. Binocular
observation is
more comfortable, less fatiguing,
and
if the microscopist uses
both eyes they are
less strained than one eye
with monocular
observation.
If you do a lot of microscopy
or use the
microscope professionally,
a microscope
with binocular tube is therefore
urgently
recommended. |
Correct magnification and criteria of
microscope performance
The correct magnification
range of a micro-
scope which suits your specific
require-
ments is determined above
all by the object
or specimen.
Which are the criteria to
judge the perform-
ance of your microscope?
You want to see
your specimen not only "enlarged"
but
sharp and you want to see
details.
The performance of a microscope
depends
on the objective. Only structures
resolved
by the microscope objective
can be
observed through the eyepiece.
The "numerical aperture"
of an objective
is a measure of its resolving
power. Every
objective bears besides
the magni-
fication the numerical aperture.
The aperture also determines
the maximum
useful eyepiece magnification,
or, in other
words, the useful total
magnification of
the microscope with a specific
objective. |
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| There are two
basic rules:
1. The
total magnification of the micro-
scope is the result of objective magni-
fication multiplied by the eyepiece
magnification. +)
2. The
total magnification of the micro-
scope should be approximately 500x to
maximum 1000x the objective aperture
(this is, according to ,
the range of "useful magnification").
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Practical experience has
shown that
contrast and sharpness are
not impaired by
values below the range of
"useful magni-
fication", for instance
if good low-power
magnifications are needed.
However, with too high a
microscope
magnification which does
not correspond
to the objective specification
you will only
see "enlarged" but neither
more nor
better.
Such ineffective over-magnification
is
called "empty magnification".
+) see the
term
of the annex. |
For your work you will depend
not only
on the high quality of your
microscope's
optics but also of the mechanical
parts.
The quality of the optical
system can be
fully utilized only if the
mechanical parts of
the microscope are crafted
with the same
degree of precision. All
objectives and
eyepieces must, of course,
be parfocalized.
Your microscope's most excessively
stressed parts such as bearing
and click-
stop mechanism of the objective
turret,
the mechanical elements
of coarse and fine
focusing controls or the
guides of the
mechanical stage for specimen
movement
never wear out, even after
years of use.
Last but not least microscopy
calls for
good illumination. Prof.
Kohler, a scientist
since 1900 stipulated in
1893 the
rules of exact microscope
illumination.
These rules are still valid
and have never
been changed.
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Illuminating
equipment for modern micro-
scope techniques is built
into the micro-
scope base, which adds to
the instrument's
compactness and sturdiness
and makes
its operation easy.
When purchasing a microscope
from
reputable company, user
must be able to
find a
nameplate sticker,
manufacturer sticker with
electrical
information's about lamps
and fuses
and electrical values,
state or province electrical
approval sticker
and warning sticker.
If you can not find electrical
approval
plate/sticker ask your dealer
to explain
it because in some countries
like USA
or Canada dealer must sell
or demonstrate
electrical approved units
only.
This law is design to protect
you -
The customer. |
Which features are different
in a stereomicroscope?
In order to get
a three-dimensional effect,
the specimen must be structured
(cavities
and protrusions), and the
depth of field
must exactly correspond
to the specimen
structure.
However, the higher the magnification
and
the larger the aperture
of the optical
system, the lower the depth
of field. When
using a stereomicroscope,
40 x to 60 x
magnification should therefore
not be
exceeded. |
Stereoscopic, that is three-dimensional
vision is possible only
by the combined
action of two eyes. This
requires inde-
pendent optical systems
for each eye, as
for instance, with
binoculars.
A stereomicroscope features
two tubes
with independent optical
systems with two
eyepieces and two objectives,
which
means that a stereomicroscope
is in fact
a combination of two monocular
micro-
scopes whose optical axes
are at an angle
to each other and directed
to the same
specimen area. |
Which microscope to choose
Whether a stereomicroscope
for reflected-
light observation or with
transilluminator, or
a regular compound microscope
is the
correct choice for your
specific problem
depends on typeand condition
of
the specimen to be
examined.
A stereomicroscope is used
for natural
specimens such as minerals,
insects, plant
parts, etc. or technical
specimens such as
coins, stamps, textiles,
electronic and
mechanical modules. Because
of its long
working distance, dissection
and precision
assembly are possible under
the stereo-
microscope.For this kind
of application
Meiji offers at a competitive
price.
EMT Stereo
Microscope
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If you want to observe small
animals in
water, sections of plant
parts, animal and
plant cells, i.e. transparent
specimens,
you need a transmitted-light
microscope
with a magnification range
from 25 x
to 400 x.
To examine bacteria, blood
counts,
chromosomes, etc. the microscope's
total
magnification should be
about 1000 x.
Meiji's easy-to-operate,
effective
ML2100 microscope in different
versions
for amateur use and colleges
is the ideal
tool for successful "microscopy
from the
very beginning ".
ML2100 |
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