By: Shefaa Hejazy.
Umm Al-Qura University, Makkah.
Faculty of Medical Sciences. Hematology Dept.
1st Semester 1433/2012
Recognize parts of a compound light microscope (LM)
Learn how to focus an object using Objective Lenses
How to adjust the light source by using the condenser
and iris diaphragm
LM in Haematology laboratory
The Microscope can magnify an object 100-1000 times of
it’s original size
A microscopic object can be visible by using a system of
lenses and illumination source
Principle and function
LM use a system of lenses (objectives and oculars) to
manage the path of light beam that travel b/w the object and
eyes in order to magnify that object
A Light compound microscope have two ocular lenses
Parts of Light Microscope
1. Eye piece (ocular lenses):
Magnifying lenses with a magnification power (10x).
2. Body tube:
Contains mirrors and prisms that transmit the image from
the objective lens to the ocular lens.
3. Objective lenses:
Primary lenses that magnify specimen
a) Low power 10x
b) High power 40x
c) Oil immersion 100x
Examination of a Wet Preparation Using 10x
and 40x Objectives:
First select the 10x objective and focus the slide using coarse
adjustment knob, by moving it up or downward. Then make it clearly
visible using the fine adjustment knob.
Turn to 40x objective and again focus using fine adjustment knob until
object is clearly visible.
Examination of stained preparation with 100x objective
Focus the smear at 10x then rotate to 100x and add a drop of oil on the
Upward the condenser and open iris diaphragm at maximum level.
Slowly upward the stage by coarse knob until the picture appear and the
objective is immersed with oil.
Use fine adjustment to gain a clear picture of the slide.
What is the total magnification power?
Power of the objective lens X Magnification of ocular lens 10x
Resolving power of the microscope:
It is a measure of its ability to distinguish b/w two adjacent objects.
The absolute limit of resolving power is the light wavelength
Maintenance of microscope
Microscope is a delicate instrument; thus it should be …
Keep in a clean environment.
Stage if contaminated should be cleaned immediately
with saline to avoid corrosion.
How to clean a microscope
The low and high power should be cleaned after and prior using with
lens paper tissue.
The Oil immersion objective lens can be cleaned with lens paper
tissue and few drops of Xyelen.
Ocular lenses: using a soft camel-hair brush.
Condenser and iris diaphragm: using a soft cloth or tissue moistened
with toluene; and the mirror with 5% alcohol.
Other parts cleaned with mild detergent. Grease/oil removed with
petroleum ether followed by 45% ethanol in water or 5% alcohol.