The Principles and Limitations of Transmission and Scanning Electron Microscopes

The Principles and Limitations of Transmission and Scanning Electron Microscopes

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The Principles and Limitations of Transmission and Scanning Electron Microscopes

Introduction

Microscopy has a major role in cytology.From the very beginning
researchers have tried to develop ways of looking directly at living
cells.This examination has revealed much about the morphology of cells
and tissues.In recent years,development in microscopes,dyes,staining
and preparatory techniques have helped reveal even more about the
structure and function of cells.Microscopes have a certain
magnification and resolving power.In any microscope the the resolving
power is more important than the magnification.The resolving power of
a microscope is the least distance between two objects where the
microscope can still distinguish the objects as being separate.It is a
measure of detail that can be seen.A microscope with a high resolving
power enables us to view images with a high resolution.With a low
resolution they would be viewed as one object.Microscopes with a high
magnification are only able to increase the size of the object that is
being viewed.The resolution will be the same.(ie the object will still
lack clarity and appear fuzzy).The two types of microscopes are
electron and light microscopes.

Principles and Limitations of light microscopy

Light microscopes function by focussing a beam of light on the object
to be examined.The beam passes through a series of lenses after
passing through the specimen.The condenser lens focuses the light onto
the specimen for maximum illumination.The lower objective lens
magnifies the object ,and the image from this lens is further enlarged
when viewed through the upper eyepiece lens.The beam f...


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...al
organisation of organelles has helped in our understanding of how they
work.The fact that electron micrographs appear in many research papers
and books in cell biology and anatomy emphasize the importance of
electron microscopy to the biologists not only in the present times
but also in future.Today electron microscopy is widely used in
metallurgy,biology,material science,physics,chemistry and many other
biological fields.It has been an integral part in the understanding of
the complexities of cellular structure,the fine structure of metals
and crystalline materials as well as numerous other areas of the
microscopic world.Although new inventions like the laser microscope
may seem to put the use of electron microscopes under threat they will
always play an integral part in determining the ultrastructure of
cells.

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