Difference Between Light and Electron Microscope

The difference between Light and Electron Microscope is mainly due to the two properties like One is a source of illumination and the Second is types of lens used.

Source of illumination: It is the property of microscope that ensures the clear visibility of the object or specimen by adding brightness to it.

Lens: It use in the microscope which can vary with different types of microscope available, and its primary function is to magnify the image.

  • The light microscope uses a direct source of light waves to visualize the image whereas the electron microscope uses a beam of an accelerated electron.
  • In light microscope combination of eye-piece, objective and condenser lens is there, which are of glass but in electron microscope combination of condenser, objective and projector lens is there, where all are made of electromagnetic material.

Content: Light Vs Electron Microscope

  1. Comparison Chart
  2. What is a Microscope?
  3. Definition
  4. Diagram
  5. Key Differences
  6. Conclusion

Comparison Chart

PropertiesLight microscopeElectron microscope
DiscoveryGiven by Zoocharia Janseen in 1590Given by Ernst Ruska and Max Knoll in 1931
Source of illuminationLight raysBeam of electron
Lens usedEye-piece, objective and condenser lensConderser,objective and projector lens
Lens typeLens are of glass materialLens are of electromagnetic material
Magnifying power1000X10,00,000X
Resolving power0.2 µm0.001 µm
Viewing screenImage is viewed directly through eye-pieceImage is viewed on fluorescent screen
Power supplyRequires low power supplyRequires high power supply
Cooling systemAbsentPresent
Sample preparationSimpleComplex
WorkingEasy to operateRequires technical skills to operate
TypesMainly of 4 types: Bright field, Dark field, Phase contrast and Fluorescence microscopeMainly of three types: SEM, TEM and STEM
Vacumn systemAbsentPresent
CostCheapExpensive
MagnificationLow, detailed structure cannot be studiedHigh, gives 3D structure of an object
Specimen used5 µm thick specimen can be easily visualizedOnly thin specimen up to 0.1 µm can be visualized
Image obtainedColouredBlack and white
Filament usageAbsentTungsten filament is used as an electron source
Radiation leakageAbsentPresent
For contrast of the imageSpecimen is stained with dyesSpecimen is coated with heavy metals

What is a Microscope?

The microscope is a device, which comprises a set of lenses which allow us to see the magnified view of an object or specimen. This device helps to study the internal and external structure of the specimen that would not be possible without the use of a microscope.

As from the name “Microscope”, it is clear that Micro: ‘Means small’ and Scope: Means ‘To look’, i.e. it defines as the instrument that allows us to look or to see the microorganisms that are invisible to the naked eye. The study of the organisms under the microscope refers to “Microscopy”.

Definition of Light & Electron Microscope

Light microscope: It also refers to as ‘Compound microscope’. It is an optical microscope which uses a ray of light to view the image where a condenser collects the light which it diverges to the specimen. It has low-resolution power comparative to the electron microscope which is 0.2 µm and magnification power is between 500 – 1000 X, which is less than the electron microscope.

Electron microscope: It is an optical microscope that uses a beam of an accelerated electron from the source of heated tungsten filament that transmits the electron to the specimen. It results in a high-resolution image of 0.001 µm resolving power that is 250 times more than the light microscope and high magnifying power of 10,00,000 X.

Diagram

Light microscope

It consists of several components like:

light microscope

Eyepiece lens: It is nearest to the eye of the observer. This lens composes of one or more lens. Observer observes the image that is first magnified by the objective lens which further magnifies through the eyepiece.

Its principal function is to convert the real intermediate enlarged image that forms by the objective lens to the enlarged virtual image.

Lens tube: It is the tube that holds an eyepiece, its length is about 160mm but can vary with different types of microscope.

Objective revolver: It holds multiple objective lenses with different magnifying power or capacity. One can spin or rotate this by one’s desire for the magnification of the specimen.

Objective lens: This lens is nearest to the specimen or object which magnifies the image by collecting light rays, then reflect it to the numerical aperture that gives a distinct view of the object.

Clip: It holds the glass slide containing the specimen sample.

Microscope stage: It provides a surface area by which one can move the object slide to one’s desire or which part of the specimen one want to study or visualize.

Condenser: It collects the light that incidents on it, which it projects back to the specimen for proper visibility.

Fine and coarse focus: Both of these regulate the distance between the object and objective by moving the microscope stage. For the sharpness of the image, one can adjust both fine and coarse focus afterwards.

Diaphragm: It adjusts the diameter of the light by preventing the image from overshine.

Light source: For this, the light microscope uses light bulb-like LED.

Stand or body: It holds all the components of the microscope.

Base: It provides stability to the microscope.

Electron microscope

It has several elements which are as follows:
electron microscope

Electron gun: It generates the beam of accelerated electron mainly through the tungsten filament by heating it to 100-1000 kV.

Condenser lens: There is two magnetic condenser lens that converges light to the specimen.

Objective lens: Magnetic objective lens focuses the electron into an object and forms the first real magnified intermediate image up to 2000times.

Projector lens: It further magnifies the real intermediate up to 240,000 or more times.

Viewing screen: The electron microscope uses a zinc sulphate fluorescent screen or photographic plate to view the image.

Camera: It is the charged coupled device that places below the viewing screen.

Specimen holder: Specimen places in a thin carbon film or collodion that holds by the metal grid.

Key Differences Between Light and Electron Microscope

  1. One of the characteristic difference is that a light microscope uses a light source whereas the electron microscope uses a beam of an electron.
  2. The electron microscope has a combination of objective, condenser and projector lens that are of electromagnetic whereas a light microscope has a combination of eyepiece, objective and condenser lens that are of glass.
  3. The light microscope shows low magnifying and resolving power of 1000X and 0.2µm respectively whereas e microscope shows high magnifying and resolving power of 10, 00,000X and 0.001µm.
  4. The object is directly visible through the eyepiece in the light microscope whereas the electron microscope makes the use of a fluorescent screen to see the enlarged view of the object.
  5. Electron microscope needs more power supply and technical skills to operate because of its complex construction and light microscope requires less power supply and easy to work.
  6. Vacuum system, tungsten filament, cooling system and radiation leakage is present in an electron microscope and absent in a light microscope.
  7. Sample preparation is easy in light microscope compared to the electron microscope.
  8. Thick specimen up to 5 µm can be easily visualized whereas electron microscope, only thin specimen up to 0.1 µm can be visualized.
  9. Specimen stains with the chemical dyes which add contrast to the microscopic image result into the coloured specimen in a light microscope. In e– microscope, the specimen is coated with heavy metals that attract the beam of an electron, and it results in a black and white specimen.
  10. Light microscope classifies broadly into a bright field, darkfield, phase contrast and fluorescent field microscope. An e microscope classifies into TEM (Transmission Electron Microscope), SEM (Scanning Electron Microscope) and STEM (Scanning Transmission Electron Microscope).

Conclusion

So finally, we have discussed the difference in properties, structure and components of both the light and electron microscope. Therefore, we can conclude that both light and e microscope works on the different principle where one uses light source the other uses the electron to see the image. The construction of both the microscope is different, where a light microscope is easy to handle and the electron microscope requires technical skill to operate.

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