Download 1_ Introduction to the Microscope

Introduction to the Microscope
What is the importance of using a microscope?
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The Purpose of a Microscope
Microscopes are used to magnify things that are
too small to be seen clearly by the naked eye.
Many things that are
known and understood
today, could not have
been discovered
without microscopes.
This is especially the case
with the life sciences.
For example, without the microscope we would
never have found out that all living things are made
from cells.
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Parts of the Light Microscope
1. Eye Piece/ Ocular
2. Arm
3. Low Power Objective
4. Stage Clips
5. Coarse Focus Adjustment
6. Fine Focus Adjustment
7. Revolving Nose Piece
8. High Power Objective
9. Stage
10. Diaphragm
11. Aperture
12. Light/ Mirror
13. Base
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Function
Eye piece/
ocular
Eye piece magnifies
objects
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Arm
Support arm - holds the
lenses in position over the
stage
Low Power
Objective
Low Power Objective –
a small lens with low
magnifying power.
Clips - to secure
specimen slide to the
stage
Stage Clips
Coarse focus
adjustment
Coarse focus dial - for
focusing and large
movements of the stage
Fine Focus
Adjustment
Fine focus dial - for
focusing and small
movements of the stage
Revolving nose
piece
Revolving nose piece - for
changing objective lenses
High Power
Objective
High-Power objective
– A large lens with
high magnifying
power.
Function
Stage
Stage - for supporting
specimen slide
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Diaphragm dial
Diaphragm dial - adjusts
the amount of light that
shines on to the slide
Aperture- hole or an
opening through which
light travels
Light/ mirror
This directs the light
upward onto the slide.
Base
Base - weighted to keep
microscope stable
Guidelines for Using the Light Microscope
Microscopes are expensive precision instruments and
must be handled with care.
Use only the
supporting arm of the
microscope to lift it.
Always carry the
microscope with one
hand underneath the
base and the other
hand holding the
supporting arm.
Keep the instrument in a box or under a cover when
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not in use.
Guidelines for Using the Light Microscope
Never touch the
lenses with your
fingers.
Keep the lenses
clean by wiping
them with lens
tissue.
Always handle
microscope slides
by their edges.
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Total Magnification
The total
magnification of an
image is equal to the
magnifying power of
the eye piece lens
multiplied by the
magnifying power of
the objective lens.
Eye piece
Objective lens
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Total Magnification
The magnifying power
of each lens is usually
inscribed on the lens
barrel.
For example, if a ×10
objective lens is used,
assuming the eye piece
magnification is ×10,
the total magnification
of the image will be
(×10) × (×10)
= × 100.
Eye piece
Objective lens
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Selecting the Lowest Power Objective
Lens
It is normal practice
to look at a specimen
using the lowest
available
magnification first,
then to look more
closely at the
specimen using a
higher magnification.
To do this, position the ×4 objective lens so that it
lies directly above the hole in the stage.
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Placing the Slide on the Stage
Before you place a
slide on the stage,
use the coarse focus
dial to position the
stage of the
microscope so that
there is at least a
2 cm gap between
the objective lens
and the stage.
Place the slide on the stage, so that the specimen is
over the middle of the hole on the stage.
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Placing the Slide on the Stage
Make sure that light
is shining through
the slide, and then
secure it in place
with the clips.
This will help to prevent the slide from being
dislodged when you are viewing it.
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Raising the Stage
Looking at the stage and the slide from the side, use
the coarse focus dial to raise the stage so that it is
as close to the objective lens as possible without
the risk of damaging the slide.
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Getting the Specimen into Focus
Looking through the
microscope eye
piece, use the coarse
focus dial to slowly
move the stage
downward.
Do this until the
specimen comes
into focus.
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Getting the Specimen into Focus
Try to keep both eyes open as you do this, as it will
help to prevent eye strain and headaches.
Never move the stage
upward when you are
looking through the
microscope eye piece.
This is because, when
using the higher
powered objective
lenses, you can easily
crush the slide and
break the lens.
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Minor Focusing Adjustments
The fine focus dial
alters the height of
the stage more
accurately than the
coarse focus dial.
You may need to make minor adjustments to the
height of the stage using the fine focus dial to get
your specimen into sharp focus.
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Adjusting the Diaphragm Dial
The diaphragm dial
can be rotated to let
different amounts of
light through the
specimen.
Finding the amount of light that produces the best
viewing results for each specimen is often a matter
of trial and error.
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Biological Drawings
It is good practice to
make biological drawings
of what you see using a
microscope.
The aim of a biological
drawing is to provide a
clear, labeled account of
what you have seen.
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Biological Drawings
Biological drawings are
useful because they:
 allow you to study a
specimen in detail
 provide a clear,
labeled account of
what you have seen
 act as a memory aid
to help you
remember what you
have seen
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Summary
In this presentation you have seen:
 the purpose of microscopes
 how a light microscope should be used
 why biological drawings are used
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Question 1
"Microscopes are used to magnify things that are too
small to be seen clearly by the naked eye."
Is this statement true or false?
Answer True or False.
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Question 1
"Microscopes are used to magnify things that are too
small to be seen clearly by the naked eye."
Is this statement true or false?
Answer True or False.
True
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Question 2
What is the purpose of the diaphragm dial on a light
microscope?
A) To magnify the specimen
B) To hold the glass slide in place
C) To change the objective lens being used
D) To adjust the amount of light that is directed
through the specimen
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Question 2
What is the purpose of the diaphragm dial on a light
microscope?
A) To magnify the specimen
B) To hold the glass slide in place
C) To change the objective lens being used
D) To adjust the amount of light that is directed
through the specimen
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Question 3
What part of the microscope is used to make
minor focusing adjustments?
A) The diaphragm
B) The coarse focusing dial
C) The fine focusing dial
D) The objective lens
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Question 3
What part of the microscope is used to make
minor focusing adjustments?
A) The diaphragm
B) The coarse focusing dial
C) The fine focusing dial
D) The objective lens
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Question 4
Which of the following states why it is useful to
make biological drawings from things you see
using a microscope?
A) To provide a clear, labeled account of what you
have seen
B) To help you to remember what you have seen
C) To allow you to study the specimen in detail
D) All of the above
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Question 4
Which of the following states why it is useful to
make biological drawings from things you see
using a microscope?
A) To provide a clear, labeled account of what you
have seen
B) To help you to remember what you have seen
C) To allow you to study the specimen in detail
D) All of the above
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