Stereo Microscope or Dissecting Miscrscope

STEREO MICROSCOPE
By Muhammad Waleed Ahsan Khan Tareen
13-arid-1100
DVM 5th (Evening)
PMAS UAAR

Definition
• The stereo or stereoscopic or dissecting microscope is an
optical microscope variant designed for low magnification
observation of a sample, typically using light reflected from
the surface of an object rather than transmitted through it.
2TAREENPIR MEHR ALI SHAH ARID AGRICULTURE UNIVERSITY

Three key parts: 1. Viewing Head/Body
• Viewing Head/Body that houses
the optical components in the
upper part of the microscope
3TAREEN
PIR MEHR ALI SHAH ARID
AGRICULTURE UNIVERSITY

2. Focus Block
• Focus Block that attaches
the microscope head to
the stand and focuses the
microscope
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3. Luminous stand
• Stand that supports
the microscope and
houses any integrated
illumination.

Conjunction purpose
• Stereo microscopes are
increasingly modular. This
means that the same head
can be used in conjunction
with different focus blocks
and stands.
• For example,
Microscope.com offers a
range of pole stands, track
stands and boom stands.
POLE STAND
BOOMSTAND
TRACK STAND
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OPTICAL COMPONENTS
• As in a compound microscope, there are two optical systems in a
compound microscope:
• Eyepiece Lenses
• Objective Lenses
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Eyepieces or Oculars & Eyepiece tube
• Eyepieces or Oculars are
what you look through at
the top of the microscope.
• Typically, standard
eyepieces have a magnifying
power of 10x.
• Optional eyepieces of
varying powers are
available, typically from 5x-
30x.
• Eyepiece tube holds the
eyepieces in place above the
objective lens.
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Objective Lenses
• Objective Lenses are the
primary optical lenses on
a microscope.
• In a low power
microscope, they provide
fixed magnification or
zoom magnification.
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Focus Control & Working Stage
• Most stereo microscopes have only
coarse focus controls
• Working Stage is where the
specimen to be viewed is placed.
Pole and track stands have simple
stages since lower magnification
powers require less subtle
movements than high power
microscopes..
• Stage Clips are used when there is
no mechanical stage.
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Transmitted Illumination
• Since most specimens examined
on a stereo microscope are
opaque, a top light (Transmitted
Illumination) is used to shed
light on the specimen. Some
stereo microscopes also include
a bottom light (Incident
Illumination).
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Modern stereomicroscope optical design. A - Objective B - Galilean telescopes (rotating objectives) C - Zoom
control D - Internal objective E - Prism F - Relay lens G - Reticle H - Eyepiece

Reticule
• A reticle, or reticule (from Latin
reticulum, meaning "net"), is a
net of fine lines or fibers in the
eyepiece of a sighting device,
such as a telescope, a telescopic
sight, a microscope, or the
screen of an oscilloscope.
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How to Calculate Stereo Microscope
Magnification
• Combination of the
eyepiece magnification
(most commonly 10x) and
the objective lens
magnification (typically
anywhere between 0.7x -
5x).
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Cont..
• If you are using a stereo
microscope with 10x eyepieces
and the zoom knob is set to 4x,
the total magnification formula
would look like this:
10 x 4 = 40x magnification
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Auxiliary lens
• The other addition that can alter total
magnification is if the stereo microscope
has an auxiliary lens added to it.
• If this is the case, the auxiliary lens is
also multiplied into the equation.
• Say you are using a stereo microscope
with 10x eyepieces, the zoom knob is set
to 5x and you also have a 0.3x auxiliary
lens on the microscope.
• Total magnification would be
determined with the following formula:
• 10 x 5 x 0.3 = 15x magnification
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STEREO MICROSCOPE: OPERATING
1. Set the microscope on a flat surface in a stable and comfortable position.
2. Turn on The Transmitted/Oblique illuminator.
3. Place a small solid specimen onto the stage such as a card, coin or any other
flat, detailed object.
4. Turn the Magnification adjustment knob to the lowest power and bring
the image into focus using the focus control.
5. Adjust the eyepieces for the correct interpupillary distance to suit you. Do
this by moving the eyepieces closer together or farther apart until a single field
of view is observed (B). Now, set the Dioptric adjustment rings on both
eyepieces to the zero position (A).
6. Use the Magnification adjustment knob to set the highest magnification.
7. Bring the image into focus with the focusing knob. Center the image on
some clear point of detail on the specimen.
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Cont..
8. Adjust the microscope down to the lowest magnification using the
Magnification adjustment knob. The image could be slightly out
of focus.
9. Do not adjust the focus with the focusing knob. Adjust the focus
for each eye separately using the eyepiece Dioptric adjustment
rings.
10. Your microscope is now "parfocal". This means that as the
microscope is zoomed from high to low magnification the image
will stay in focus throughout the entire range. Each individual will
have a different setting.
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Basic Groups of Stereomicroscope
Greenough Design
• Old design
• Used in production processes for
soldering on a miniature scale and
dissecting specimens
• The advantage of the Greenough
design is the similarity to a compound
microscope since it allows selection of
high apertures.
Common Main Objective
• New design
• Used in research and development
because of its high resolution and the
optical and illumination accessories
available
• The CMO uses a large, single objective
lens, which is shared by a pair of ocular
channels and lens assembly.
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Anomalies
Greenough Design
• The disadvantage is what's known as
the keystone effect. This is a slight tilt in
the focal plane due to the two lenses
viewing the same image at slight angles.
• As the lenses are not exactly parallel, this
results in the outside of the image in the
field of view to be slightly over focused or
under focused. Therefore, only the central
regions of the image are correctly focused
at identical magnifications.
Common Main Objective
• This design virtually eliminates any image
tilt in the focal plane. However, it creates
an optical anomaly that makes the viewed
object appear to elevate in the center, also
referred to as “perspective distortion”.
• This is more of a problem in the less
expensive CMO stereo microscopes so
those used in top research, being more
expensive and made by a major
manufacturer, should not have this
distortion.
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Cont..
Greenough Design Common Main Objective

Difference between CMO & GREENOUGH designs
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Types of stereo
Stereo Fixed Microscope
• The term “fixed" refers to one of the
microscopes used in stereo microscopy.
• The fixed magnification uses two objective
lenses, which refer to the optical element
gathering and focusing the light rays on the
image.
• The magnification has a fixed degree and is
limited to the capability of the lens.
Changing to a stronger eyepiece increases
the magnification.
• This can be useful as you cannot change to a
higher or lower magnification while viewing
a specimen, therefore it keeps a stable focus.
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Types of stereo
Stereo Turret Microscope
• These types of microscopes come in a
variety of mountings, one of which is a
turret style.
• Objective turret is another term for this
type of mounting and indicates that an
additional objective lens can be rotated
into viewing position.
• This easily allows the viewer to change
magnifications by simply rotating the
turret mounting.
• Stereo turret microscopes are less
flexible than the zoom type but are a
more economical choice.
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Types of stereo
Stereo Zoom Microscope
• The stereo zoom microscope behaves much as
its name implies and is very popular. This
microscope can zoom in or out to increase or
decrease the desired magnification. The
available range can also be altered by changing
to a stronger eyepiece.
• The stereo zoom microscope comes with a
choice of stands:
a) A simple stand allows room for observation
and repair of items such as watches, coins,
entomology
b) A boom stand is for larger applications and
can be mounted to the floor and have an added
boom to act as a counterweight..
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Digital display with stereo microscopes
• Recently, video dual camera
pickups have been fitted to
stereo microscopes, allowing
the images to be displayed on a
high resolution LCD monitor.
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Uses of stereomicroscope
• Erect & Three dimensional perspective
• Insects disection
• Detailed work such as microsurgery & watch making
• Commercial inspection applications such as
– soldering
– circuit board inspection
– repair
– engraving
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Stereo Microscope or Dissecting Miscrscope

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