What are 3 differences between a light microscope and an electron microscope?

Microscopes are used to know the exact shape, function, and other features of microorganism, which are invisible from naked eyes though vital from biological aspects. The word microscope is taken from a Greek word where ‘mikros‘ means “small”, and ‘skopeo‘ means “to look at”.

The use of lenses started in Europe in the 16th century. It is believed that Dutch spectacles makers Zacharius Jansen and his father Hans were the first to invent the compound microscope in the 16th century. Later, Robert Hooke, Anton van Leeuwenhoek, Joseph Jackson Liste, and Ernst Abbe kept on advancing it and invented the Phase  Contrast microscope.

A few years later Electron Microscope was developed by Ernst Ruska and Max Knoll, with the use of ‘electrons’ in the microscope instead of visible light which helped in increasing the resolution of the lens along with more magnified and cleared image of an organism.

Later with the invention of scanning the tunneling microscope, 3-D images viewing started and this was developed by Gerd Binnig and Heinrich Rohrer. This content will provide the important points which distinguish the Light microscope to that of Electron microscope.

Content: Light Microscope Vs Electron Microscope

Comparison Chart

Definition of Light Microscope

The instrument used in labs to observe and study smaller organisms is called a microscope. Light microscope contains an Eyepiece (Ocular lens), tube, coarse focus, fine focus, resolving nose piece, objective, stage clips, diaphragm, mirror, light source, condenser, three or four objective lenses.

The light microscope uses the visible light as the source to view the object, along with glass lenses/transparent lenses and projection screen. As these microscopes are easy to handle and simple & easy in working. They can be commonly seen in schools, colleges labs, doctors clinic.

The microscope is based on its resolving power, magnification, lenses used, source to view the object. “Resolving power” is the most important, which is the ability to differentiate two very small and closely attached objects clearly. Lesser the distance between the objects, finer will be the result.

Light Microscope also referred as Optical Microscope can be classified as Simple and Compound Microscope. In the simple type single lens like magnifying glass are only used, whereas in compound type several lenses are used to magnify the objects clearly.

Types of Light (compound) Microscope

1. Bright Field Microscope.
2. Dark Field Microscope.
3. Phase Contrast Microscope.
4. Fluorescence Microscope.
5. Differential Interference Contrast Microscope.
6. Confocal Microscope.
7. Ultraviolet Microscope.

Advantages and Disadvantages

Following are the advantages and disadvantages of Light Microscope
 Advantages 

• Easily available, less expensive simple to use.
• Living as well as dead organisms can be viewed.
• No effect of magnification.
• The natural colour of the sample is obtained.
• No need of high voltage electricity.
• The image can be seen directly.

Disadvantages 

• Magnification up to 1000X only.
• Resolving power of only 0.2um.
• Unable to provide the information and structural information of very small organisms.
• Light does not follow the exact straight path.
• Sometimes preparation of a sample may disturb the specimen.
• Although it provides the details about the morphology of biomolecules and biomolecular complexes but is unable to give details about the individual atom.

Definition of Electron Microscope

Nowadays, an electron microscope is much widely used by scientists and in research labs to get the keen knowledge of even the smallest microorganisms as well as to study all their characteristics in detail. As the name suggests, Electron Microscope uses electrons instead of visible light source to view the objects.

Electrons microscopes are the most advanced type of microscopes. In the year 1920, it was recognized that electrons when moved in a vacuum, they behave like “light”. They travel in straight lines and have wavelike properties, with a wavelength much shorter than that of visible light.

Types of Electron Microscope

1. Scanning Electron Microscope (SEM).
2. Transmission Electron Microscope (TEM).
3. Scanning Transmission Electron Microscope.
4. Focused Ion Beam and Electron Microscope.

Advantages and Disadvantages

Following are the advantages and disadvantages of Electron Microscope
Advantages

• Resolving power of less than 0.5nm which is more than 400 times better than a typical Light Microscope.
• Magnification of 10,00,000X times.
• 3D image is obtained
• Wavelength is 100,000 times shorter than visible light, hence much more clarity.
• As resolving power is only 0.2nm electron microscope produces a detailed image of organelles present inside the cells.

Disadvantages

• Only black and white images are produced.
• Complex in operating.
• Too expensive, not easily available.
• Only dead(fixed) organisms can be viewed.
• The image is seen only on fluorescent screen.
• Risk of leakage of radiation.

Key Differences Between Light Microscope and Electron Microscope

Following are the  main differences between Light Microscope and Electron Microscope:

1.  Light Microscope uses visible light, and Electron Microscope uses electrons (beam of charged particles) to view the object.
2. Magnification and Resolving power also varies of both, Light Microscope has the magnification of around 1000X with resolving power of 0.2um, whereas Electron Microscope has the magnification of 10,00,000X and resolving power up to 0.5nm.
3. In Light Microscope projection screen and glass lenses are used but in Electron Microscope fluorescent screen and an Electromagnetic screen is used.
4. Living and natural color of the specimen is obtained, but dead(fixed), black and white but 3D images are obtained.
5. Light Microscopes are easy to handle, less expensive and easily available, Electron Microscope is expensive and not easy to handle.
6.  It is believed that Dutch spectacles makers Zacharius Jansen and his father Hans were the first to invent the compound microscope in the 16th century while the Electron Microscope was invented by physicist Ernst Ruska and German engineer Max Knoll in 1931.
7. There is the requirement of high voltage which is around 50,000 and above in Electron Microscope along with the cooling system also, which is required to move out the heat generated due to high voltage. In case of Light Microscope, there is no such requirement.
8. Tungsten filament is used in Electron Microscope, even there is the risk of leakage, while there is no risk of radiation in Light Microscope.

Conclusion

Though both the microscopes are important and have some positive and negative factors, nowadays Electron Microscopes are broadly used by scientists in a research laboratory to do the detailed study of organisms whereas Light Microscopes are used by schools, colleges, path labs for viewing the organisms which are easily visible through it.

Even earlier we were unaware of the diseases like tuberculosis, typhoid, dysentery, measles, etc. as well their causes and remedies, but since the time of the invention of the microscope, scientists were able to resolve them.

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