Light Microscope
Faculty of science, Department of biology
First stage
By
Aveen Kh. Khalid
Light Microscope
What is a microscope:A microscope is an optical instrument consisting of a combination
of lenses, which magnifies the image of the object seen, thought it.
It is used for the morphological study of very small organisms,
which are not visible to the naked eye.
Lab 1
botany
Types of microscopes:
1. Simple microscope
2. Compound microscope.
3. Dark field microscope.
4. Fluorescent microscope
5. Electron microscope that include two types.
1. Scanning microscope.
2. Transmission microscopes.
Compound microscope:- Parts of
1- Eye piece (ocular) lens: magnifying lens usually about 10X or 5X
The ocular or eye piece is a complex piece, located at the top of
the instrument that consists of
two or more internal lenses and usually has magnification of 10x .
Binocular microscope:-which has two eye-pieces.
Monocular microscope:-which has single eye-pieces.
2- Objective lens: a number of lenses that provide different magnification
The four objectives are attached to the revolving nose-piece,
which makes it possible to move them into position over a slide
a. Low power objective 4x,10x
b. High power objective 40x
c. Oil_ immersion objective 100x
3- Light source:- It is fixed in the base of microscope.
4- Diaphragm:- Controls the amount of light that enters the objective lens.
5- Condenser: Which is located under the stage ,it is made up of a system of
convex lenses which collects and directs the light from the light source to the slide
being studied. focuses the light, does not affect the magnification power.
6- Fine adjustment:- It is used with the high power and oil immersion
objective lenses.
7- Big adjustment (coarse adjustment):- It is used with the low power
objective lens, it is controlled by a pair of large knobs.
8- The arm.
9- Base or foot.
10- Revolving nosepiece.
11- Mechanical stage: It is horizontal platform, has a hole in it. On
this the slide with the specimen is held with clips .It can be fixed or
mobile. The mechanical stage adjustments move the slide in two
directions, horizontally and vertically.
Magnification:- Magnification means the degree of
enlargement that is the number of times the length,
diameter is multiplied.
• Total magnification:We can calculate total magnification of specimen by.
Multiply objective lens magnification by ocular lens magnification.
Most ocular magnification is = 10x.
If objective lens magnification is= 10x.
Total magnification is =10*10= 100X
How to use the microscope
1- Be sure of the lenses clear
2- Put your sample on the stage
3- Be sure of the stability of your sample
4- Use the lower magnify lens 4X then the other 10X, 40X and 100X until to reach
to clear picture.