What is Microscope?
A microscope is a laboratory instrument used to
examine objects that are too small to be seen by
the naked eye. It is derived from Ancient Greek
words and composed of mikrós, “small” and
skopeîn,”to look” or “see”.
Base
Supports the microscope
It is one of the most revolutionized scientific
instruments used to observe or examine minute
structures not clearly visible from naked eyes.
Arm
Used
to
microscope
Stage
Platform where the slide with
the specimen is placed
Stage Clips
Holds the slide in place on
the stage
Eyepiece
(containing
ocular lens)
Magnifies the image for the
viewer
Revolving
nose piece
Contains
the
objective
lenses; rotates to allow the
user to switch between
different objective lenses
Objective
lenses
Low-, medium-, and highpower lenses that further
magnify the specimen at
different intensities
Coarse
adjustment
knob
Large
knob used for
focusing the image under
low
power
(general
focusing)
Fine
adjustment
knob
Smaller knob used for
focusing the image with the
medium- and high-power
objectives (fine-tuning)
Diaphragm
Controls the amount of light
that passes through the
specimen
Light source
Provides light for viewing the
specimen
In 1665, for the first time Robert Hooke made an
impressive Micrographic illustration using
microscope. Antonie van Leeuwenhoek,
another scientist made significant contribution in
microscope research by magnifying the simple
single lens microscope 300 times.
Microscope
Parts
Microscope Parts
Functions
carry
the
Structure of Microscope
What Microscope does?
Microscopes magnify or enlarge small objects
such as cells, microbes, bacteria, viruses,
microorganisms etc. at a viewable scale for
examination and analysis.
Microscopes consist of one or more
magnification lenses to enlarge the image of the
microscopic objects placed in the focal plane.
The magnification power of simple laboratory
microscope is 1250x.
Microscope Parts and their Functions
In general, microscopes are made up of
supporting parts to hold the structure of
Microscopes and optical parts, consist of lenses
used to magnify the specimens.
The description given below summarize the
brief description of microscope parts used to
visualize the microscopic specimens such as
animal cells, plant cells, microbes, bacteria,
viruses, microorganisms etc.
of microscope is used to reflect light from the
external light source up through the bottom of
the stage. Usually, the Illuminator located in the
base of the microscope. Most light microscopes
use low voltage, halogen bulbs with continuous
variable lighting control located within the base.
Stage with Stage Clips: The stage of a
microscope is a flat platform where you place
your subject slides. Stage clips hold the slides
in place. The mechanical stage of your
microscope will help you to move the slide
around by turning two knobs. One knob moves
it left and right, the other knobs move it up and
down.
Revolving Nosepiece or Turret: Turret is the
part of the microscope that holds two or multiple
objective lenses and helps to rotate objective
lenses and also helps to easily change power.
Objective Lenses: Three are 3 or 4 objective
lenses on a microscope. The objective lenses
almost always consist of 4x, 10x, 40x and 100x
powers. The most common eyepiece lens is 10x
and when it coupled with others, total
magnification is 40x (4x times 10x), 100x, 400x
and 1000x. Objectives can be forward or rearfacing.
The Microscopes parts divided into three different
structural parts Head, Base, and Arms.
Head/Body: It contain the optical parts in the
upper part of the microscope.
Arm: It supports the tube and connects it to the
base.
Base: The bottom of the microscope, used for
support.
Microscope Rack Stop Rack Stop: Rack Stop
is an important microscope parts that
determines how close the objective lens can get
to the slide. It keeps the students from
damaging the high-power objective lens down
into the slide. If you can’t able to focus on the
specimen at high power while using very thin
slides then slight adjustment helps you to adjust
the focus.
Tube: Connects the eyepiece to the objective
lenses.
Diaphragm or Iris: Most of the laboratory
microscopes have a rotating disk under the
stage known as diaphragm or iris. Iris
Diaphragm controls the amount of light reaching
the specimen. The Iris Diaphragm is located
above the condenser lens and below the
microscope stage.
Illuminator: Illuminator is the most important
microscope parts and it serve as light source for
a
microscope
during
slide
specimen
visualization. It is a continuous source of light
(110 volts) used in place of a mirror. The mirror
The different sized holes in the diaphragm helps
to vary the size of the cone and intensity of light
that is projected upward into the slide. However,
there is no set rule regarding which setting to
use for a particular power.
Optical Components of Microscope
Eyepiece Lens: the lens at the top that you look
through, usually 10x or 15x power.
The specimen transparency, degree of contrast
and particular objective lens in use decide the
Diaphragm or Iris setting. Majority of highquality microscopes used in laboratory include
an Abbe condenser with an iris diaphragm.
When iris diaphragm is combined with Abbe
condenser, it controls both the quantity of light
applied as well as focus on the specimen.
Aperture: It is the hole in the stage through
which the base (transmitted) light reaches the
stage.
Condenser: Condenser lenses are used to
collect and focus the light from the illuminator on
to the specimen. Usually the Condenser lenses
are located under the stage in conjunction with
an iris diaphragm. Condenser lenses helps in
ensuring clear and sharp images are produced
with a high magnification of 400X and above.
Magnification power of the condenser is directly
related to the image clarity. Most of the
sophisticated microscopes in the laboratory
come with an Abbe condenser that has a high
magnification of about 1000X. Condenser
Focus Knob moves the condenser up or down
to control the lighting focus on the specimen.
FAQ About Microscope and
Microscope Parts
What is Microscope?
Microscopes are instruments that are used in
science laboratories, to visualize very minute
objects such as cells, microorganisms, giving a
contrasting image, that is magnified.
What is the Function of Microscope?
A microscope is usually used for the study of
microscopic algae, fungi, and biological
specimens.
What is Magnification?
Magnification is the process of maximizing
object’s relative size rather than its physical
size. This expansion is measured by a
calculated number known as “magnification.”
Whenever this number is less than one, it
corresponds to a reduction in size, also known
as minification or de-magnification.
What is Resolution?
The term ‘resolution’ in microscopy refers to a
microscope’s ability to differentiate object’s
details. In other words, this is the smallest
distance at which two distinct points of a
specimen can still be seen as separate entities
– either by the observer or the microscope
camera. A microscope’s resolution is
inextricably linked to the numerical aperture
(NA) of the optical components as well as the
wavelength of light used to examine a
specimen.
What is Depth of Field?
The depth of field is defined as the distance
between the nearest and farthest object planes
that are both in focus at any given moment. In
microscopy, the depth of field is how far above
and below the sample plane the objective lens
and the specimen can be while remaining in
perfect focus.
What is Eyepiece?
The eyepiece, also known as the ocular is the
part used to look through the microscope. Its
found at the top of the microscope. Its standard
magnification is 10x with an optional eyepiece
having magnifications from 5X – 30X.
What are Objective Lens?
Objective Lens are the major lenses used for
specimen
visualization.
They have
a
magnification power of 40x-100x. There are
about 1- 4 objective lenses placed on one
microscope, in that some are rare facing and
others face forward.
What is Coarse Adjustment?
The coarse adjustment knob moves the stage
up and down to bring the specimen into focus.
What is Fine Adjustment?
What is Microscopy Staining?
The fine adjustment knob brings the specimen
into sharp focus under low power and is used for
all focusing when using high-power lenses.
Cell staining is a technique used to enhance the
visibility of cells and cell components under a
microscope. Different stains can be used to
stain specific cell components, such as the
nucleus or the cell wall, or the entire cell with
different colours.
What are Condensers Lenses?
Condensers are lenses that are used to collect
and focus light from the illuminator into the
specimen. They are found under the stage next
to the diaphragm of the microscope. They play
a major role in ensuring clear sharp images are
produced with a high magnification of 400X and
above.
What are Abbe Condenser Lenses?
What are Basic Components of Optical
Microscope?
Almost all optical microscopes have a tube, an
eyepiece lens, a turret with one or more
objective lenses, a light source, an aperture, a
condenser, a stage, fine and coarse focus
controls, and a stable base.
Abbe condenser is a condenser specially
designed on high-quality microscopes, which
makes the condenser to be movable and allows
very high magnification of above 400X. Highquality microscopes normally have a high
numerical aperture than objective lenses.
What is Microscopy in Biology?
Can I See Germs Under a Microscope?
Why is it Necessary to Begin with 4x
Magnification on a Microscope?
Due to very small size of germs, an amateur
microscope will not allow you to see germs.
Germs can only be observed under a
microscope with a magnification of at least
1200x. In order to visualize the germs, and the
specimen must be stained.
As a result, you’ll need to use a powerful
microscope model and special sample
preparation techniques. Of course, there are
giants among bacteria that can be seen at 900x
magnification, but they live at the deepest
depths of the ocean and are nearly impossible
to obtain.
Can a Light (Optical) Microscope Detect
Viruses?
No, they are 1000 times smaller than bacteria,
which is the smallest thing an optical
microscope can see.
In biology, the most important way to gain
insight into biological structures and processes
is through microscopy, or studying biological
forms with an optical microscope.
The 4x objective lens has the least amount of
power and thus the greatest field of view. As a
result, locating the specimen on the slide is
easier than if you start with a higher power
objective.
How to Calculate Magnification of a
Microscope?
Simply multiply the magnification of the ocular
lens by the magnification of the objective lens to
calculate the power of magnification of a
microscope.
For
a
typical
compound
microscope with a 10X ocular lens and objective
lenses with magnifications of 4X, 10X, 40X, and
100X, your microscope will have magnifications
of 40X, 100X, 400X, and 1000X depending on
which objective lens you use. The same
principle applies to stereo microscopes; a 10X
eyepiece combined with a 4X objective lens
produces a magnification of 40X.
Some stereo microscopes have a continuous
zoom objective lens with magnification ranging
from 0.75X to 7.5X. When combined with a 10X
ocular lens, the total magnification will be 7.5X
to 75X. When combined with a 25X ocular lens,
the total magnification will be 18.75X to 187.5X.
What is Field of View (FOV)?
When looking through a microscope, the FOV is
the diameter of the circle of light that you see.
The field of view shrinks as magnification power
increases, and vice versa.
How Does the Diopter Adjustment
Work?"
To compensate for the difference in vision
between your two eyes, the diopter adjustment
allows you to focus one eyepiece independently
of the other. When the diopter adjustment is
correct, both eyes are at ease during
observations.
How to Calculate Total Magnification?
Magnification refers to how much larger an
object appears when viewed through a
microscope versus the naked eye. The
multiplication symbol (X) on the eye piece and
objective lenses indicates how many times the
lens of each microscope part magnifies an
object.
Multiply the magnification of the eyepiece
(ocular lens) by the magnification of the
objective lens in use to calculate the total
magnification of any object viewed under the
microscope. This can be demonstrated using
the formula.
Total magnification = ocular lens x objective
lens
For example, if the ocular lens magnifies the
image 4X and the low-power objective lens
magnifies the image 10X, the total
magnification of the object at low
magnification is 40X (4×10=40X). The total
magnification would be 160X (4 x 40= 160X)
with the same ocular lens and a high – power
objective that magnifies 40X.
What is the Best Way to Use a
Microscope?
• Step 1: Connect the light microscope to a
power source in step one. You can skip this
step if your microscope has a mirror instead of
an illuminator. Instead, look for a location with
plenty of natural light.
• Step 2: Rotate the revolving nosepiece so
that the lowest objective lens is in place.
• Step 3: Install your specimen on the stage.
But first, make sure your specimen is
adequately protected by placing a coverslip on
top of it.
• Step 4: Use the metal clips to secure your
slide. Make sure the specimen is in the centre,
directly beneath the lowest objective lens.
• Step 5: Looking through the eyepiece,
slowly turn the coarse adjustment knob to
bring your specimen into focus. Make sure the
slide does not come into contact with the lens.
• Step 6: Set the condenser to produce the
most light possible. Because you’re using a
low power objective, you may need to reduce
the illumination. To make adjustments, use
the diaphragm beneath the stage.
• Step 7: Slowly turn the fine adjustment knob
until you have a clearer image of your
specimen.
• Step 8: Inspect your specimen.
• Step 9: Once you’ve finished viewing with
the low-power objective, switch to the
medium-power objective and re-adjust the
focus with the fine adjustment knob.
• Step 10: Once you’ve focused the lowpower objective, move on to the high-power
objective.
Safety Precautions for Using
Microscopes
Carrying: Carry your microscope with two
hands, one grasping the arm or back slot and
the other supporting the base.
Table Placement: Position the microscope
on flat, solid support that will not be easily
knocked off. To avoid tripping over the cord,
coil it.
Cleaning: Lenses must be clean in order for
resolution to be achieved. Only lens paper or
gauze and cleaning solution should be used.
Never clean your lenses with your finger,
handkerchief, paper towels, or spit. Remove
no parts for cleaning; doing so allows dust to
enter the microscope.
Electron Microscopes vs Light
Microscopes
Light
Microscope
Electron
Microscope
Size
Small
Very large
Training
required
Extensive
training
Little;
necessary:
suitable for only
middlelaboratory
school
personnel in
students as research
well as older institutions
will
have
access
Feature
Viewing
specimens
Can
see
color?
Live
live specimens
can
be
viewed
Live
specimens
cannot
be
viewed
No, because
electrons
are used to
Yes, since
generate an
light is used
in
image. Any
to illuminate
colors seen
the
are
specimen
computergenerated
for clarity
1000X
maximum
up to around
10,000,000X
(some can
view atoms)
Vague;
generally
Clarity/resolution
poor
resolution
Very clear;
very
high
resolution
and clarity
Total
magnification