Differences between light and electron microscope

 

Differences between light and electron microscope

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S.N.	Character	Light Microscope	Electron Microscope
1.	Alternatively known as	Optical microscope	Beam microscope
2.	Invented by	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.	In 1931 physicist Ernst Ruska and German engineer Max Knoll.
3.	Illuminating source	Uses light (approx wavelength 400-700 nm) to illuminate the objects under view.	Uses a beam of electrons (approx equivalent wavelength 1 nm) to make objects larger for a detailed view.
4.	Principle	The image formed by absorption of light waves.	The image formed by scattering or transmission of electrons.
5.	Structure	Light microscopes are smaller and lighter.	Heavier and larger in size.
6.	Lenses used	Lenses are made of glass.	Lenses are made of electromagnets.
7.	Vacuum	Not used under a vacuum	Operates under a high vacuum
8.	Specimen type	Fixed or unfixed, stained or unstained, living or non-living.	Fixed, stained and non-living.
9.	Specimen observed	Both live and dead specimens can be observed.	Only dead specimens are possible to be observed.
10.	Specimen preparation	Less tedious and simple.	It generally involves harsher processes, e.g. using corrosive chemicals. More skill required – both to prepare specimens and to interpret EM images (due to artifacts).
11.	Preparation time	Specimen preparation takes usually a few minutes to hours.	Specimen preparation takes usually takes a few days.
12.	Thickness of specimen	5 micrometer or thicker	Ultra-thin, 0.1 micrometers or below
13.	Dehydration of Specimen	Specimens need not be dehydrated before viewing.	Only dehydrated specimens are used.
14.	Coating of specimen	Stained by colored dyes for proper visualization.	Coated with heavy metals to reflect electrons.
15.	Mounting of specimen	Mounted on the glass slide.	Mounted on the metallic grid (mostly copper).
16.	Focusing	Done by adjusting the lens position mechanically.	Done by adjusting the power of the electric current to the electromagnetic lenses.
17.	Magnification power	Low magnification of up to 1,500x.	High magnification of up to 1,000,000x.
18.	Resolving power	Low resolving power, usually below 0.30µm.	The high resolving power of up to 0.001µm, about 250 times higher than the light microscope.
19.	Viewing of the image formed	Light microscope images can be viewed directly. Images are viewed by the eyes through the eyepiece.	Images are viewed on a photographic plate or zinc sulfate fluorescent screen.
20.	Nature of Image formed	Poor surface view	Good surface view and internal details
21.	Image Color	Colored images.	Electron microscopes produce grayscale (sometimes called “black and white”) images (except “false-color” electron micrographs).
22.	Image dimension	Image plane “flat” (2D).	2D only in a Transmission electron microscope (TEM);  Scanning electron microscope (SEM) images give depth information which seems like 3D.
23.	Living processes	Visualization of living processes such as microscopic pond life in action and even cell division is possible.	Living processes cannot be viewed.
24.	Room settings	No special settings required.	It must be used in a room where humidity, pressure, and temperature are controlled.
25.	Simplicity in use	Simple to use	Users require technical skills

26.	Electric Current	No need for high voltage electricity.	High voltage electric current is required (50,000 V or above).
27.	Filaments	No filaments used.	Tungsten filaments used to generate electrons.
28.	Cooling System	Absent	Cooling system present to pacify the heat generated due to high voltage electric current.
29.	Radiation leakage	No radiation risk.	Risk of radiation leakage.
30.	Complexity	Less complex	Complex
31.	Expense	Cheap to buy and has low maintenance costs.	Very expensive to buy as well as to maintain.
32.	Suitability /   Practicality	Suitable for most basic functions, and is very common in schools and other learning institutions.	Limited to specialized use such as research.
33.	Advantages	·         Easy to use ·         Cheap ·         True color but sometimes require staining ·         Live specimens	·         High resolution ·         Provide detailed images of surface structures and interior structures ·         High magnification ·         3D images
34.	Disadvantages	·         Low resolution due to shorter wavelength of light (0.2nm) ·         Low magnification ·         The specimen used is thin.	·         Expensive ·         Requires extensive training ·         Sample must be dead ·         Black and white/false-color image
35.	Types/ Variants	·         Dark-field microscope ·         Phase-contrast microscope ·         Fluorescent microscope Confocal microscope Polarized microscope ·         Differential interference contrast microscope	·         Transmission electron microscope (TEM) ·         Scanning electron microscope (SEM)
36.	Application	It is used for the study of detailed gross internal structure.	It is used in the study of the external surface, the ultrastructure of cell and very small organisms.