A microscope is a device used to observe minute objects invisible to the naked eye. It is one of the important discoveries which helped in the progression of science and medicine. This microscope is of two types like
Light microscope (compound microscope)
Both are meant for magnification of minute objects but the resolution of the latter is very high compared to the former.
Difference between light microscope and electron microscope
|Properties||Light Microscope||Electron Microscope|
|Principle||The visible light passes through the
specimen. The magnified image
formed by the objective lens is
further enlarged by one or more
additional lenses (eyepiece).
|In an electron microscope, a beam of electrons is used to magnify the
specimen images at very high
|The light microscope has a less resolving power of around 0.25µm to 0.3 µm.||The resolving power of an
an electron microscope is (0.001 µm), which many folds higher than the light microscope.
|In 1590 Zacharius Jansen and his father Hans designed the microscope.||In 1931 Ernst Ruska and
German engineer Max Knoll,
they are physicist invented the electron microscope.
|Method||In a light microscope, the glass lenses and the visible spectrum of light are involved.||In an electron microscope, the
electromagnetic lenses and the beam of electrons for image formations are involved.
|Vacuum||There is no requirement of a vacuum condition to working with a light microscope.||Since an electron microscope uses an electron beam. Its short
wavelength can be retarded and deflected easily by the molecules in the air. So, a vacuum condition is mandatory in an electron
|Mounting the specimen||In Light microscope, the specimen is mounted on the glass slide attached to the stage.||In the Electron microscope, the
the specimen is mounted on the a metallic grid that placed on the stage.
|In the light microscope, the magnification changes occur according to the
use of different objective lenses
|In the electron microscope, the power of the electric current adjustments changes the magnification.|
|Visibility||After focusing the image in the light microscope, it can be
observed within our naked eye.
|After focusing, the visualization of the image by fluorescent screen or photographic plates are used, because the electron beam cannot be seen by our naked human eye, so the image cannot be observed by naked eyes.|
|Cost factor||The light microscope is inexpensive and hence widely used in
schools and college labs.
|The electron microscope is very expensive in terms of instrument and usage.|
|Size of instrument||The light microscope is very small; it occupies a place of a
|The electron microscope requires a large space. A separate facility for systems like cooling system, vacuum system, image processing system, etc. is needed.|
|Photographs||The photograph of the image in the light microscope is colored because the staining procedure will produce colors.||In an electron microscope, the
a photograph is not colored, only black and white images are captured, but if we want a color pseudo-color (false color) is used
|Specimen size||The specimen size wants to be less than 5µm thick that can be
|To visualize the image in the
the electron microscope, the specimen size wants to be only 0.1µm.
|Filaments||In the light microscope, there
should not be used any of the filaments.
|Tungsten filament is used to
produce the electron beam in the electron microscope.
|Image Formation||To focus the image, the light scatters and passes through the
specimen and reaches the objective lens, then it is re-directed to the objective lens and passes through the eyepiece for the visualization.
|The electron emitted in the vacuum, are attracted by the specimen and appears dark on the micrograph, while other areas appear bright on the micrograph.|
|Resolution||The typical resolution of the light microscope is 200nm.
200nm = 200 X 10 -9 m
= 2X10 -7 m.
|The typical resolution of the
electron microscope is the 0.5nm. 0.5nm = 0.5 X 10 -9 m
= % X 10 -8 m.
|Magnification||The magnification range for the light microscope between x1000 and x2000.||The magnification range for the electron microscope up to
X 10, 000,000.
SEM: X100, 000.
TEM: X250, 000.
|View of Living cells||In the light microscope, we can observe the living cells and activity/
e.g., Bacteria movement in action.
|Due to the vacuum present inside the electron microscope, we cannot observe the living creatures’ movement as they would be dead.|
|Visible wavelength of
|The approximate wavelength for the electron microscope is <1nm.|
|Types||The light microscope is of four
1) Bright-field microscope
2) Darkfield microscope
4) Fluorescent Microscope
|The electron microscope is of two basic types like
1) Transmission Electron
2) Scanning Electron
|The same preparations like the fixation and staining. The freeze- etching technique is involved in the preparation of the specimen to visualize the image by the TEM and SEM.|