Microscopes
What is a microscope?
A microscope is a high precision optical instrument that uses a lens or a combination of lenses to produce highly magnified images of small specimens or objects especially when they are too small to be seen by the naked (unaided) eye. A light source is used (either by mirrors or lamps) to make it easier to see the subject matter.
What is microscopy?
Microscopy is the use of a microscope or investigation by a microscope.
Who invented the microscope?
There is no one person who invented the microscope as several different inventors experimented with theories and ideas and developed different parts of the concept as they evolved to what is today’s microscopes.
About 1590 two Dutch spectacle makers, Zaccharias Janssen and his son Hans, experimented with a crude concept of a microscope that enlarged objects 10x to 30x or so.
In 1609, Galileo (an Italian) improved on the principle of lenses and added a focusing device to improve somewhat upon what the Janssen’s had done.
These rudimentary instruments didn’t change much until the early 1670s.
A Dutchman, Anton van Leeuwenhoek, is considered the father of microscopes because of the advances he made in microscope design and use. He worked as an apprentice in a dry goods store where magnifying lenses were used to count the threads in cloth. Anton was inspired by these glasses and he taught himself new methods for grinding and polishing small lenses which magnified up to 270x.
This led to the first practical microscopes. In 1674, Anton was the first to see and describe bacteria, yeast, plants, and life in a drop of water.
Not many improvements were made until the 1850’s when several inventors in Europe and America made vast improvements. From this time frame, modern compound and stereo microscopes have changed very little.
In the early 1930’s the first electron beam microscopes were developed which were a breakthrough in technology as they increased the magnification from about 1000x or so up to 250,000x or more. These microscopes use electrons rather than light to examine objects.
What can you do with a microscope ?
A microscope can be used for numerous things:
hobbyists have an interest in microscopic worlds from learning and having fun to using a microscope for the study of stamps, coins, gems, insects, etc
children can view a fantastic world of discovery
students have an interest in pursuing knowledge anywhere from middle school through the university level
medical uses from analysis to advanced research in many and varied disciplines
industrial uses as inspection and measurement tools
government and scientific uses for public safety and discovery
imaging of whatever you are looking at.
Parts of a Microscope
LABORATORY EXPERIMENT ON THE FUNCTIONS OF THE COMPONENT OF A
SIMPLE MICROSCOPE.
BY
EMMANUEL AKAISO
MSC. ENVIRONMENTAL SCIENCE
QUESTION: WHAT ARE THE FUNCTIONS OF THE COMPONENT OF A
MICROSCOPE?
A SIMPLE MICROSCOPE.
The following are the parts of microscope:-
Eyepiece or ocular lens: Eyepiece is the lens, present at the top and is used to see the objects
under study. Eyepiece lens contains a magnification of 10X or 15X.
Tube: Tube or the body tube, connects the eyepiece to the objective lenses.
Resolving nosepiece: It is also known as the Turret. Resolving nosepiece has holders for the
different objective lenses. It allows the rotation of the lenses while viewing.
Objective lenses: Generally, three or four objective lenses are found on a microscope, with
ranges of 10X, 40X, 100X powers. Lenses are colour coded, the shortest lens is of the lowest
power, and the longest lens is high power lenses.
Diaphragm: Diaphragm helps in controlling the amount of light that is passing through the
opening of the stage. It is helpful in the adjustment of the control of light that enters.
Coarse adjustment knob: Used for focus on scanning. Usually the low power lens is used
enabling the movement of the tube.
Fine adjustment knob: Used for focus on oil. Moves the body tube for focusing the high power
lens.
Arm: It supports the tube of the microscope and connects to the base of the microscope.
Stage: The platform that is flat used for placing the slides under observation.
Stage clip: Stage clips hold the slides in proper place.
Condensor: The main function of condenser lens is focusing the light on the specimen under
observation. When very high powers of 400X are used, condenser lenses are very important.
Presence of condenser lens gives a sharper image as compared to the microscope with no
condenser lens.
Base: Provides basal support for the microscope.
Power switch: The main power switch that turns the illumination on or off
The following are the parts of microscope:-
Eyepiece or ocular lens:
Eyepiece is the lens, present at the top and is used to see the objectsunder study. Eyepiece lens contains a magnification of 10X or 15X.
Tube:
Tube or the body tube, connects the eyepiece to the objective lenses.
Resolving nosepiece:
It is also known as the Turret. Resolving nosepiece has holders for the different objective lenses. It allows the rotation of the lenses while viewing.
Objective lenses:
Generally, three or four objective lenses are found on a microscope, with ranges of 10X, 40X, 100X powers. Lenses are colour coded, the shortest lens is of the lowest power, and the longest lens is high power lenses.
Diaphragm:
Diaphragm helps in controlling the amount of light that is passing through the opening of the stage. It is helpful in the adjustment of the control of light that enters.
Coarse adjustment knob:
Used for focus on scanning. Usually the low power lens is used enabling the movement of the tube.
Fine adjustment knob:
Used for focus on oil. Moves the body tube for focusing the high power lens.
Arm:
It supports the tube of the microscope and connects to the base of the microscope.
Stage:
The platform that is flat used for placing the slides under observation.Stage clip: Stage clips hold the slides in proper place.
Condensor:
The main function of condenser lens is focusing the light on the specimen under observation. When very high powers of 400X are used, condenser lenses are very important. Presence of condenser lens gives a sharper image as compared to the microscope with no condenser lens.
Base:
Provides basal support for the microscope.
Power switch:
The main power switch that turns the illumination on or off.
Microscopy Categories
Microscopes are categorized as:
1. Light (optical) microscopes
2. Electron microscopes
Light microscopy is further categorized as
1. Polarizing Microscope
2. Reflected Light Microscope,
3. Bright field microscopy
4. Dark field
5. Phase contrast microscopy
6. Fluorescence microscopy.
Electron microcopy is of two types
1. Transmission microscopy
2. Scanning Electron microscopy
Basic Principle of light microscopy
The basic principle of the light microscope is shown in Fig. An image of the
object (specimen) is formed by the objective lens, which typically provides a
magnification in the range 10x to 100x. This magnified image is then viewed
through the eyepiece (ocular), whose magnification is usually 10x.
The total magnification of a microscope is obtained by multiplying the objective
and eyepiece magnifications. Typically total magnifications are in the range 100X
to 1000X.
Magnification
In order to ascertain the total magnification when viewing an image with a compound light microscope, take the power of the objective lens which is at 4x, 10x or 40x and multiply it by the power of the eyepiece which is typically 10x.
Therefore, a 10x eyepiece used with a 40X objective lens, will produce a magnification of 400X. The naked eye can now view the specimen at a magnification 400 times greater and so microscopic details are revealed.
Magnification is the ability to view an object as larger. A good image is obtained when the amount of specimen detail is also increased. Magnification alone will not achieve this.
Resolution
Good resolution or the resolving power of the microscope is necessary to see the valuable details comprised in an image.
Resolving Power is the ability to measure the separation of images that are close together.
Optical quality plays a vital role but the distance of the wavelength of light used is crucial.
- Teacher: Dr. Saima Naz
- Teacher: Dr. Tasleem kausar
- Teacher: Dr. Saima Naz