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Introduction of Electron Microscope

Electron Microscope with its various parts as shown above picture. The organelles of the cell became known after the electron microscope was invented. It was developed in 1931 by Max Knoll and  Ernst Ruska in Germany. It consists of a source of supplying, a beam of electron of uniform velocity, a condenser lens for concentrating the electron on the specimen, a specimen stage for displacing the specimen which transmits the electron beam, an objective lens, a projector lens, and a fluorescent screen on which final image is observed.

For permanent records of the image, the fluorescent screen is replaced by photographic film. This microscope utilizes a stream of high-speed electrons which are deflected by an electromagnetic field in the same way as a beam of light is reflected when it crosses a glass lens.

Types of Electron Microscope

There are two types of electron microscopes and the are-

1. Transmission  and
2. Scanning

Transmission electron microscope (TEM)

• This is used to observe the fine structure of cells. Ultra-thin sections of the object are prepared and they are stained with a heavy metal (gold or palladium) to make certain parts dense and inserted in the vacuum chamber of the microscope.
• A 100, 00-volt electron beam is focused on the section and manipulated prepared from the image may be enlarged with enough resolution to achieve a total magnification of over 10 million times.

Scanning electron microscope (SEM)

• It is used to study the surfaces of the cell and organisms.
• In this microscope, the image is formed by electrons reflected back from the object.
• The image formed by this microscope has a remarkable three-dimensional appearance. Typically magnification of scanning electron microscope is 10 to 500,000 times.

Differences between light microscope and electron microscopes

Following are the differences between them-

Applications of Electron Microscope

1. application in cancer research
2. used to investigate the ultrastructure of a wide range of biological specimens including microorganisms, cells, large molecules, and materials science as well as pollution.
3. nanotechnology and
4. semiconductor research

References

1. https://www.sciencedirect.com/topics/physics-and-astronomy/electron-microscopes
2. https://www.britannica.com/technology/field-emission-microscope
3. https://www.hitachi-hightech.com/eu/product_list/?ld=sms2&md=sms2-1&version=
4. https://bitesizebio.com/29197/introduction-electron-microscopy-biologists/
5. https://www.horiba.com/en_en/cathodoluminescence-spectroscopy-electron-microscope/
6. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/light-microscopes
7. http://www.biologyreference.com/La-Ma/Light-Microscopy.html