Light microscopy is a general term used for any type of microscopy where light is being transmitted from a source which is on the opposite side of the sample, to the objective lens. Generally, the light is passed through a condenser to focus it on the sample to have maximum brightness. After the light has passed through the sample, it goes through the objective lens to magnify the image of the sample & then to the oculars, where the enlarged image is viewed. Image Microscope Light microscopic techniques have significantly developed over the past 20 years & now provide an indispensable tool to study molecular events at subcellular level in order to gain temporal & spatial information at high resolution. To achieve optimal results, it is essential to carefully plan & carry out microscopy-based experiments, which requires the understanding of at least the basics of cell biology, sample preparation & fluorescence light microscopy.

2. The
Compound
Microscope
PARTS AND FUNCTIONS

3. Learning Competency:
Identify the parts and functions, and
demonstrate proper handling and storing of
a compound microscope

4. 1.What part of the microscope
should you hold when carrying
it?
a) The base and the arm
b) The stage
c) The eyepiece
d) The objective lenses

5. 2.Which part of the microscope is
used to adjust the focus on the
specimen?
a) The arm
b) The coarse and fine focus knobs
c) The base
d) The illuminator

6. 3. What is the function of the objective
lens on a compound microscope?
a) To support the microscope slide
b) To reflect light towards the eyepiece
c) To magnify the specimen for viewing
d) To adjust the amount of light passing
through the specimen

7. 4. When storing the microscope, what
position should the objective lenses be
in?
a) The highest power objective lens should be
clicked into place
b) The lowest power objective lens should be
clicked into place
c) Any objective lens can be clicked into place
d) The objective lenses should be removed

8. 5. Which part of the microscope
allows you to change between
different objective lenses?
a) The stage
b) The eyepiece
c) The nosepiece
d) The diaphragm

9. The correct answers are:
1.a) The base and the arm
2.b) The coarse and fine focus knobs
3.c) To magnify the specimen for viewing
4.b) The lowest power objective lens should be
clicked into place
5.c) The nosepiece

10. Microscope
A microscope is an instrument
that produces enlarged images of
small objects, allowing the
observer to closely examine
minute structures that are
otherwise too small to be seen by
the naked eye.

11. Here are some key points about
microscopes:
1. Optical Microscopes:
•Definition: Optical
microscopes use glass
lenses to magnify objects.
They are the most familiar
type of microscope.

12. Uses:
• Biological Research: Scientists use
optical microscopes to study cells,
tissues, and microorganisms.
• Medical Diagnosis: Doctors use them to
examine blood samples, diagnose
diseases, and identify pathogens.
• Education: Microscopes are essential
tools in schools and universities for
teaching biology and other sciences.

13. Types of Optical Microscopes:
•Compound Microscope: Consists of multiple lenses
(objectives and ocular) and uses visible light. It can
magnify up to 2,000×.
•Darkfield Microscope: Creates a white specimen
against a black background by scattering light.
•Fluorescence Microscope: Uses ultraviolet light to
view fluorescently labeled specimens.
•Contrast/Phase Microscope: Examines structures
inside cells using different refractive indexes

14. Parts of the Compound Microscope
The compound microscope has three
main parts:
◦Magnifying parts
◦Illuminating parts
◦Mechanical Parts

15. Magnifying Parts
The magnifying parts are used to enlarge
the view of specimens. It includes the
following:
1.Objective lens
2.Ocular lens / Eyepiece

16. 1. Objective Lens
The most important of the optical parts.
Commonly, there are three or four objective
lenses:
◦Scanner
◦low power objective (LPO)
◦high power objective (HPO)
◦oil immersion objective (OIO)

17. OBJECTIVE LENS

18. Objective Lens
◦Scanner – marked with a red line and the
shortest among the other objective and is
usually marked 4x.
◦low power objective (LPO) – marked with a
yellow line and usually have a magnification
power 10x. It locates and shows the structure
of the specimen.

19. ◦high power objective (HPO) – is a long and slender and
is usually marked 40x or 60x. It shows the detailed
structure of the specimen.
◦oil immersion objective (OIO) – is a special type of
objective lens; it may be long or short. It is used to
increase the resolution of microscope. It has a small
lens at its end that is usually marked 99x or 100x. A
drop of cedar oil is used on the specimen before it is
viewed under the lens.
Objective Lens

20. 2. Ocular lens / Eyepiece
Magnifies the image formed by the
objectives. It is attached to the upper
end of the microscope and usually
marked 5x, 10x, 15x or 20x.

22. Illuminating Parts
The illuminating parts are used to supply light
to the slide on the stage. Following are these
parts:
1.Mirror
2.Numerical Aperture
3.Condenser
4.Iris Diaphragm

24. 1. Mirror
- collects and reflects light from an external
light source up into the microscope. It has
adjustable sides that may be plain or concave.
2. Numerical aperture
- measures the microscope’s ability to
gather light an resolve fine details of a specimen
at a fixed distance.

25. 3. Condenser
- directs the maximum amount of light upon
an object.
4. Iris Diaphragm
- a flat disc located beneath the
condenser. It has an adjustable opening or
aperture hat may be reduced or enlarged to any
size by adjusting its lever.

26. Mechanical Parts
The mechanical parts are used to support and
move parts of the microscope. Following are these
parts:
1.Arm 7. Revolving nosepiece
2.Stage 8. Base
3.Stage Clips 9. Inclination joint
4.Body tube
5.Draw tube
6.Adjustment knobs

27. 1. Arm
- the bent or curved structure that supports the
stage and body tube.
2. Stage
- the platform where the slide is placed.
3. Stage Clips
- hold the prepared slide firmly on the
stage.

28. 4. Body tube
- holds the draw tube and connects the eyepiece
to the objectives.
5. Draw tube
- houses the ocular lens. It is fitted inside the
upper end of the body tube.
6. Adjustment Knobs
- bring the objects into focus so that the view
of the specimen appears sharp and clear.

29. 7. Revolving nosepiece
- supports the objectives and enables them to be
positioned in the desired place.
8. Base
- anchors the microscope firmly on the table.
9. Inclination joint
- allows the upper part of the microscope to
be bent.