MICROSCOPE FOR

BMLS-1
DEPARTMENT OF PARASITOLOGY/MED ENTOMOLOGY
OUTLINE
• Introduction
• Historical background
• Types of the microscope
• Essential parts of compound microscope
• Working principle and how to use microscope
• Care and maintenance of microscope
Introduction
• The word “microscope” comes from the Latin “microscopium,”
which is derived from the Greek words “mikros,” meaning “small,”
and “skopein,” meaning “to look at.”

• MICROSCOPE: Is an optical instruments having magnifying lens or

combination of lenses used to view small objects that can not be seen
by naked eyes or which are not clearly differentiated by naked
 
Historical background
• 1590 - Hans Janssen and his son Zacharias Janssen,
developed first microscope.
• 1609 - Galileo Galilei - compound microscope.
• 1620 - Christian Huygens, another Dutchman,
developed a simple 2-lens ocular system.
• 1667: Robert Hooke's
famous "Micrographia" outlines Hooke's various
studies using the microscope
 Historical background
• 1675: Enter Anton van Leeuwenhoek, used a microscope
with one lens to observe insects and other specimen.
• 1830: Joseph Jackson Lister discovers that using weak
lenses together at various distances provided clear
magnification.
• 1903: Richard Zsigmondy invents the ultramicroscope,
which allows for observation of specimens below the
wavelength of light.
• 1938:   Ernst Ruska developed electron microscope,
 Types of Microscopes

LIGHT MICROSCOPE
Is the most common microscope found in the laboratory which use
visible projected light to illuminate and magnify an object .
FLUORESCENT MICROSCOPE
Is the microscope which use ultra violet as source of light to illuminate
and magnify an object.
Types of Microscopes cont.
ELECTRON MICROSCOPE
Is the kind of microscope which use the beam of electron
as energy source for illumination of an object
1.Transmission electron microscope.
2 .Scanning electron microscope.
X-RAY MICROSCOPE
Is kind of microscope which use beam of x rays to create
image, electromagnetic radiation in the soft X-ray band
produce magnified images of objects. Since X-rays
penetrate most objects, there is no need special
preparation of material to be observed by using X-ray
microscopy .
CONT….
CONFOCAL MICROSCOPE
Is a specialized form of standard fluorescence microscope  that uses
particular optical components to generate high-resolution images of material
stained with florescence probes 
Fluorescent probes are molecules that absorb light of a specific wavelength
and emit light of a different, typically longer, wavelength (a process known
as fluorescence), and are used to study biological samples.

DISSECTION MICROSCOPE(STEREO MICROSCOPE)

• Used to view various parts of Arthropods during identification
Binocular Compound microscope .
Fluorescence microscope
Confocal microscope
Electron microscope
Dissection microscope
Essential parts of compound microscope
The MICROSCOPE: Your primary tool
Components of the microscope

Support System
1. Base – must rest on a firm, flat bench or table
2. Arm – supports the main tube and the mechanical stage
3. Mechanical Stage – holds the slide secure and allows the
specimen moved smoothly backwards, forwards and sideways.
Vernier scale: can be used to trace a part of the blood film you
need to re-examine
Components of the microscope

Magnification System
1. Revolving Nosepiece – holds the objective lenses of different
magnification
2. Objectives – x4, x10,x40,x100
3. Eyepiece – x10
Components of the microscope
ILLUMINATION SYSTEM
1. Main Tube
2. Body Tube (Prism)
3. Sub stage Condenser
- made up of number of lenses
- centers the light from the mirror or electric light source to central
spot on microscopic field
- can be raised or lowered to give maximum/minimum illumination.
4. Iris diaphragm - controls the amount of light passing through the
condenser
Components of the microscope

5. Filter holder & filter – blue filter make microscopic field

white rather than yellow
6. Mirror – use to direct light from light source to the
microscopic field.
Adjustment System
1. Coarse Adjustment – use to focus the specimen being
examined
2. Fine Adjustment – for finer focusing
Components AND FUNCTION
• Eyepiece Lens: the lens at the top that you look through.
They are usually 10X o power.
• Tube:  connects the eyepiece to the objective lenses.
• Arm:  supports the tube and connects it to the base. It is 
used along with the base to carry the microscope.
• Base:  the bottom of the microscope, used for support
• Illuminator: a steady light source (110 volts) used in place of a mirror.
• Stage: the flat platform where you place your slides. Stage clips hold the
slides in place.
Components AND FUNCTION
• Revolving Nosepiece or Turret: 
This is the part that holds bjective lenses and can be rotated to
easily change power.

• Objective Lenses:  They  always consist of  4X
or5X, 10X, 40X and 100X powers. 

• When coupled with a 10X (most common) eyepiece lens, we get total 
magnifications of 40X (4X times 10X), 100X , 400X and 1000X.
Components AND FUNCTION
• Diaphragm/Iris: many microscopes have a rotating disk under the
stage and has different sized holes used to vary the intensity and
size of the cone of light that is projected upward into the slide. 
• Coarse adjustment: this is used to focus the microscope. Its always
used first, and its used only with the low power objective.
• Fine adjustment: this is used to focus the microscope. Used to bring
the specimen into better focus.
Working Principle Of Microscope
• Light passes through transparent object, the objective lens produced a
magnified image which is the first image ,this image is again
magnified by ocular to obtain the magnified image which is virtual
image that can be seen by eyes through eyepiece as light passes direct
from the source to eyes through lenses, the field of vision is brightly
illuminated
• The light passing through the specimen can be controlled by the iris
diaphragm.
•  When using objective lens of higher magnification, more light is
required to see the image clearly.  
Working Principle Of Microscope
How to use a microscope

• Position the microscope correctly and identify the essential parts.

• Cleaned all parts of microscope
• Before switching on the microscope turn the lamp brilliance control to
its lowest setting, then increase it to about three quarters of its power.
• Bring the 10 objective into place.
Using Microscope cont..
• Make sure the underside of the specimen slide and surface of the stage
are completely
dry and clean.
• Place the specimen on the stage in the slide holder.
• Focus the specimen with the 10 objective.
• The condenser (should be within 1 mm of its topmost position) and
leave it in this position for all objectives.
Using Microscope cont.
• Examine the specimen with the 10 objective
• Use the mechanical stage to examine the specimen systematically.
• Examine the specimen with the 40 objective if needed

• Examine the specimen with the 100 objective if needed after addition
of a drop of oil immersion on the specimen.
• Obtain the best image by opening the iris fully and increasing the
illumination.
Terms used in magnification
MAGNIFICATION Degree of enlargement , no of times the length,
breadth or diameter, of an object is multiplied which depends upon
– Optical tube length
– Focal length of objective
– Magnifying power of eye piece
• TOTAL MAGNIFICATION: magnification of the eyepiece x
magnification of the objective.
Terms used in magnification cont.
RESOLUTION •Ability to reveal closely adjacent structural details as
separate and distinct.
LIMIT OF RESOLUTION (LR): The minimum distance between two
visible bodies at which they can be seen as separate and not in contact with
each other.
USEFUL MAGNIFICATION The objective provides all the detail available
in the image. The eyepiece makes the detail large enough to be seen
OIL IMMERSION is a solution  of high refractive index used to increase the
resolving power of a microscope by increasing the numerical aperture of the
X100 objective lens.
Terms used in magnification cont.
• Resolving power denotes the smallest detail that
a microscope can resolve when imaging a specimen. The smaller the
distance between the two points that can be distinguished, the higher
the resolving power.
• Empty magnification occurs when the image continues to be
enlarged, but no additional detail is resolved. This is often the case
when higher magnification eyepieces are used.
•  Microscopy is the technical field of using microscopes to view small
objects.
CORRECTLY CARRYING A MICROSCOPE

 correct
– using both hands
– support base and arm

 incorrect
– using one hand
– no support

32
Handling
• Always clean lenses at the end of the day using lens tissue and
cleaning fluid
• Routine servicing should be performed at least once a year
(minimum) by a qualified technician and include:
 inspection and cleaning of internal fungus, dust
 inspection and repair of optical alignment
 inspection and repair of slide holding stage mechanism
 lubrication of stage mechanism
 general inspection and repair
Care and Maintenance
The eyepieces
• Clean upper lens with a lenses tissues

• Clean lower lens with fine brush

The condenser
• Clean the same way as the objectives using soft cloth

The support and stage

• Clean using soft cloth
Care and Maintenance
Care and Maintenance
Laboratories with electricity
– A warm cupboard heated by 1 or 2 light bulbs (40 W)

Laboratories without electricity

– A desiccator 15-20 cm in diameter with no less than 250 g of dry

blue silica gel (which indicates humidity by turning pink)

Important: The microscopes must be kept in the warm cupboard even

if the laboratory is air- conditioned.
User’s Preventive Maintenance
The following should be performed weekly:
• Clean the unit

• Check the physical condition of power cord, plug, eyepieces,

condenser, objectives, reflector, stage, fine and coarse adjustment

knob, and grounding system
• Lubricate rollers (if you are aware of the procedure) and other

movable parts
• Check fine and coarse adjustment
Don’ts

• Clean the lenses of the objectives and eyepieces with xylene

• Dip the objectives in xylene
• Use ordinary paper or cotton wool to clean the lenses
• Touch the objectives with your finger
• Lower the x 100 lens to the slide
Don’ts
• Clean the inside lenses of eyepieces and objectives with cloth or paper
• Keep the microscope in a closed wooden box in hot humid places
• Leave the microscope without the eyepiece covered
• Carry the microscope by the limb with one hand
• Expose the microscope to direct sunlight
Don’ts
• Exchange lenses from microscope of different manufacturer - even
some models by the same manufacturer have different specifications
• Dismantle or try to clean parts of the microscope difficult to reach
unless you have been trained
• Use xylene at all.
Good microscopy practices (Do’s )
• Cover the microscope when not in use
• Line up the x5 objective (or empty socket) with the ocular when
microscope is not in use
• Lower the stage and the condenser
• Adjust with x 10 before moving x 100 lens to slide
• Oil immersion objective must be cleaned after use
• Report to the Maintenance Department if any malfunction observed
 MICROSCOPE MAINTAINACE CHART
MICROSCOPE

ID: # _____________________________ MONTH _________2022

DATE OF MONTH
DAILY MAINTENANCE 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Check all optics for damage

Check coarse / fine adjustments

Dust/clean surfaces of scope components

Clean external surface

Remove oil

Replace bulbs as needed

Microscope covered after use

TECH’S INITIALS

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