LIGHT MICROSCOPY by SIVASANGARI SHANMUGAM The optical microscope, The functions of a light microscope is based on its ability to focus a beam of light through, which is very small and transparent, to produce an image.

1. SIVASANGARI SHANMUGAM
LIGHT MICROSCOPY

2. CONTENTS
1. Introduction
2. Types
3. Principles
4. How does it work?
5. Applications
6. Advantages
7. Disadvantages

3. INTRODUCTION
 Also known as optical microscope.
 It is a biology laboratory instrument.
 That is uses visible light to detect and magnify very small objects & enlarging
them.
 They use lens to focus light on the specimen, magnifying it thus producing an
image. The specimen is normally placed close to the microscopic lens.
 Microscope magnification varies greatly depending on the types and number
of lenses.

5. TYPES
Simple Light
Microscope
• Contain Single
lens.
• It has low
magnification.
Compound
Light
Microscope
• Contain Two set
of lens.
• Has higher
magnification.
Monocular
Microscope
Contain one eye
piece
Binocular
Microscope
Contain two eye
piece
Reduce eye strain
There are four types of microscope

6. TYPES

7.  The functions of light microscope is based on its ability to focus a
beam of light through, which is very small and transparent, to
produce an image.
 The image is then passed through one (or) two lenses for
magnification for viewing.
 The transparency of the specimen allows easy and quick penetration
of light.
 Specimens can vary from bacterial to cells and other microbial
particles.

8. PRINCIPLE  Light is produced from either an internal (or) external
light source and passes through the iris diaphragm, a
hole variable size which controls the amount of light
reaching the specimen.
 The light then passes through the condenser which
focuses the light onto the specimen.
 The slide is held on the stage at 90° to the path of
light which next travels through the specimen.
 The objective lens magnifies the image of the
specimen before the light travels through the barrel
of the microscope.
 Finally light is passes through the eyepieces lens &
into the viewer’s eye which sends impulses to the
brain which in turn interprets the image.

9. PARTS OF LIGHT MICROSCOPE
1. Eye lens/Ocular lens
2. Objective lens
3. Condenser
4. Beam of light
5. Specimen stage
6. Aperture diaphragm

10.  Objective lens - made up of six or more glasses, which make the image
clear from the object.
 Condenser - mounted below the stage which focuses a beam of light onto
the specimen. It can be fixed or movable, to adjust the quality of light, but
this entirely depends on the microscope.
 Stage - where the specimen is placed, allowing movement of the specimen
around for better viewing with the flexible knobs and it is where the light is
focused on.
 Light illuminator/mirror - found at the base or on the microbes of the
nosepiece.
 Aperture diaphragm - known as the contrast, which controls the
diameter of the beam of light that passes through the condenser.

11. HOW DOES IT WORKS?

12. HOW DOES IT WORKS?
 Light microscope is compound microscope which means that contain at least two
lenses.
 Lenses are bended glass pieces.
 Light from the mirror is reflected up through the specimen, to be viewed, into the
powerful objective lens, which produce the on magnification.
 The image produced by objective lens is than magnified again by the eyepiece
lens, which act as a single magnifying glass.
 The magnified image can be seen by looking into the eyepiece lens.
 Important factors are Magnification, Resolution, Contrast.

13. APPLICATIONS
1. A combination of staining and light microscopy can allow scientists to
identify different kinds of bacteria.
2. Light microscope play a large part in today’s biology.
3. Observe real time movement in cells and organisms.
4. Biologist use microbes to observe objects and details at a cellular level to
learn more about the building blocks of all organisms.

14. ADVANTAGES
1. Relatively easy to use.
2. Small and Lightweight.
3. It offer high levels of observational quality.
4. It is unaffected by electromagnetic fields.
5. Do not require radiation to operate.
6. Require very little training.
7. Allow to observe living organisms.
8. Have minor maintenance cost compared to other models.
9. Fully adjustable to the comfort level of the user.

15. DISADVANTAGES
1. Have a lower resolution.
2. Making it challenging to view living internal structures.
3. Cannot operate in darkness.
4. Cannot provide 3D renderings.
5. Very low magnification caps.

16. OTHER TYPES
The modern types of Light Microscopes include:
1. Bright Field Light Microscope
2. Phase Contrast Light Microscope
3. Dark Field Light Microscope
4. Fluorescence Light Microscope
5. Confocal Light microscope

17. REFERENCE
1. https://study.com/academy/lesson/light-microscope-definition-uses-
parts.html
2. https://www.thoughtco.com/history-of-the-microscope-1992146
3. https://www.studyblue.com/notes/note/n/chapter-2-microscopy-exam-
i/deck/9442340
4. https://www.sciencedirect.com/topics/agricultural-and-biological-
sciences/light-microscopes
5. https://www.sciencedirect.com/science/article/pii/B9781782420743000179
6. https://www.quora.com/What-is-the-major-difference-between-Phase-
contrast-microscopy-and-Dark-field-microscopy

18. THANK YOU