Science has led to the discovery of several laboratory instruments. These instruments are used in different procedures for different purposes. A microscope is a laboratory instrument used to produce an enlarged image of a biological or non-biological object, otherwise invisible to the naked eye. The observer can have a closer look at the object under examination to see the minute details. Different types of microscopes have variating magnifications and resolution powers. Light microscopes are the earliest microscopes to be developed. It uses a light source that forms the image of the object.
Another type of microscope is the electron microscope. This type provides greater magnification than the light microscope. On this platform, we will discover all about electron microscopes, from their discovery to their types to their advantages and disadvantages.
Table of Contents
What is an Electron Microscope?
An electron microscope uses a beam of electrons to produce an image of an object. The wavelength of electrons is 100,000 shorter than that of light, so it is used to identify and observe very small objects and their structures. Using an electron microscope, a wide range of biological and non-biological specimens, including atoms, molecules, microorganisms, cells, biopsy samples, and crystals can be observed.
How Does an Electron Microscope Work?
An electron microscope uses an accelerated beam of electrons instead of light for illumination. The following steps mention how an electron microscope works to form the image of the object to be observed.
- An electron source, a heated tungsten filament is used to generate a high-energy beam of electrons having a voltage of 5-100 KeV.
- Using a positive electrical potential, the beam of electrons is accelerated in a vacuum.
- The stream of electrons is focused into a monochromatic beam directed toward the specimen.
- A magnetic lens is used to focus the beam onto the specimen.
- The electron beam is affected by the interaction occurring inside the irradiated sample.
- These interactions are first detected and then transformed into an image.
What is the Advantage of Electron Microscope?
The advantages of an electron microscope are greater than a light microscope. These advantages are mentioned in detail below:
High Magnification and Resolution
Electron microscopes have magnification and resolution power higher than the light microscope. With an electron microscope, you can see structures that are otherwise invisible in a light microscope. The resolution of an electron microscope ranges up to 0.2 nm which is 1000 times higher than the light microscope.
Wide Range of Applications
The use of electron microscopes is adopted in plenty of fields, including research, industries, chemistry, pharmaceutical, biomedical science, forensic medicine, and technology. The applications include quality control and assurance, drug development, semiconductor inspection, analysis of atomic structures, and computer chip manufacture.
Using the electron microscope correctly can produce images of high quality. The images formed by an electron microscope are detailed and show complex and delicate structures. Such high-quality images are not formed by any other type of microscope.
What is the Disadvantage of Electron Microscope?
The disadvantages of electron microscope include:
- It only forms black-and-white images.
- They are costly.
- Electron microscopes are difficult to carry and keep as they are large.
- Electron microscopes require specimens to be observed under a vacuum to avoid the scattering of electrons. Thus, living specimens cannot be observed using an electron microscope.
- Special training is required to observe objects with an electron microscope.
History of Electron Microscope
If you wonder who invented the electron microscope, we have the answer! The prototype of an electron microscope was designed and developed in 1931 by a German engineer, Ernst Ruska. Reinhold Rudenberg developed a patent for the microscope. In 1932, the first images were produced using the prototype of the electron microscope. However, in 1933 Ernst Ruska used the concepts of Reinhold Rudenberg’s patent to develop an electron microscope with greater resolution than an electron microscope.
In 1938, Siemens developed the first commercial microscope. Currently, microscopes having 2 million magnification power are being used in different industries, and all are based on the principle of Ernst Ruska’s prototype.
Types of Electron Microscopes
There are two main types of electron microscope, including scanning electron microscope (SEM) and transmission electron microscope (TEM).
Transmission Electron Microscope (TEM)
TEM is considered the first type of electron microscope that can magnify the objects up to 2 million times. They have a resolution power of up to 0.2 nm. It utilizes an electron beam to form an image. An electron gun located at the top of the TEM is used to emit electrons that pass through the vacuum. TEM employs the use of an electromagnetic lens instead of the glass lens. Transmission electron microscopes are commonly used in nanotechnology, medical and forensic analysis.
Scanning Electron Microscope (SEM)
When comprehending transmission vs scanning electron microscope, the SEM is ten times less powerful than TEMs. However, the images produced by them are sharper having high resolution. It produces the image by using a beam of electrons to scan the surface of the specimen. The electrons interact with the atoms of the sample producing signals containing information about the composition of the sample or specimen. It is used for failure analysis and quality control. They have a resolution power ranging between 1 to 20 nm.
Microscopes are an important laboratory instrument. They are used to see objects that are way too small to be seen with the naked eye. Microscopes produce an enlarged image of the specimen under observation. It allows us to see minute details and complex structures within a specimen. Electron microscopes are the newest and most advanced type of microscopes. Instead of light, electron microscopes use a beam of accelerated electrons to create an image. Electron microscopes have high magnification power than any light microscope. They are used in different fields, including research, forensics, biomedical, pharmaceutical, technology, etc.
Frequently Asked Questions (FAQs)
Here are a few frequently asked questions about electron microscopes:
What are the components of an electron microscope?
There are four main components found in an electron microscope. These are:
- electron optical column
- vacuum system
- necessary electronics, including lens supplies and high-voltage generator
What is the magnification and resolution power of an electron microscope?
The magnification power of an electron microscope is 10,000,000x, whereas the resolution power is 50 picometers (0.05 nanometers).
Is a scanning electron microscope (SEM) better than a transmission electron microscope (TEM)?
A scanning electron microscope is better than a transmission electron microscope as it is easy to use, gives faster results, requires less preparation, and is less expensive.