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The Cell

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Structure and function of a light microscope

Development of the light microscope

In 1650, Zacharias Jansen invented the compound microscope which combined of two lenses for greater magnification.

In 1665, Robert Hooke used an improved compound microscope to observe cells.

Between 1650 and 1700, Anthony Van Leewenhoeck developed a better microscope with lenses which provided a greater magnification. He used the microscope to view nuclei and unicellular organisms including bacteria.

Electron microscope

The development of the electron microscope in 1930s significantly improved microbial studies.Through this microscope, it was possible to study very finer details of structures.


light microscope

This is the most commonly used microscope in schools and institutions that do not focus on very fine details of the internal structures of cells.

The light microscope uses a beam of light to illuminate the specimen being studied.
Image:Parts of a microscope

A microscope is a delicate and expensive instrument that should be handled with care. It is imperative to understand the parts and functions of various parts of a microscope.

In a light microscope, the eye piece and the objective lenses both contribute to the magnification of the specimen.

The total magnification of the specimen viewed under a light microscope will be given by:
Magnification= Eyepiece lens magnification X Objective lens magnification

In particular, if the eyepiece lens magnification is X10 and objective lens magnification power is X8, then the total magnification of the specimen would be: Magnification=Eyepiece magnification X Objective lens magnification = 10 X8 =X80.



 
Part of the Microscope Function of the Part
Limb/arm Supports the body tube and stage
Base Provides firm and steady support to the microscope
Body Tube Holds the eyepiece and the revolving nose piece
Coarse adjustment knob Raises or lowers the body tube for longer distances to bring the image into sharper focus
Fine adjustment knob Raises or lowers the body tube through smaller distances to bring the image into sharper focus. It is mostly used with the high power objective lens
Diaphragm An aperture that regulates the amount of light passing through the condenser to illuminate the specimen
Eye-piece Contains a lens which contributes to the magnification of the specimen under review
Objective lens Brings image into focus and magnifies it
Mirror Reflects light through the condenser to the object on the stage
Revolving nose-piece Holds the objective lenses in place and enables the change from one objective lens to the other
Condenser Concentrates light on the object on the stage
Stage Flat platform where specimen on the slide is placed.It has two clips to hold the slide into position.

 
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