Table of Contents:

1. Introduction
2. What is a light microscope?
   1. Key components of light microscopy
3. What are the types of light microscopy
4. Advantages of optical microscopy
5. Application of light microscopy in biology
6. Conclusion

A light microscope is a tool that can identify, observe and magnify objects by transmitting light through a string of lenses. It is one of the most used tools in the field of biology. Microscopes are rightly used in medicine, microbiology, mineralogy and material science. The application of light microscopy can augment the vision of microorganisms by making them look large.

The history of compound light microscopes began in the middle ages. Scientifically, it was discovered by two Dutch scientists Hans Janssen and his son Zacharias. They were the first to experiment in the last decade of the 16th century by combining lenses in a tube and concluded objects to appear larger and closer. This magnification could be adjusted between 3 and 9x.

And then something unbelievable happened. Living cells were observed for the first time by a cloth merchant. Dutchman Antoni Van Leeuwenhoek made a simple microscope as a hobby and managed to magnify living organisms by more than 200 times.

Before we get into some deep insights into light microscopy, run through these basics.

• Light microscopy is also known as optical microscopy.
• The optical scanning microscope was invented in 1935.
• The smallest sample traced by a light microscope would be a 500 nanometer-long object.

What is a light microscope?

To begin with, the invention of microscopes has significantly contributed to modern medicine. Nothing about cells was known before the origination of microscopes. Until then, it was firmly believed that poisonous gases and evil spirits caused diseases. The invention of microscopes led to the recognition of microorganisms and other bacteria, thereby developing proper treatments.

With light microscopy, small specimens are made visible by throwing light into a team bean and creating an image to understand how the structure interacts with the light. Some parameters like the reflection, absorption and scattering of the sample get discovered.

The biology laboratory instrument tool manoeuvres lenses (depending upon the type of microscopy) to produce the image. The process is carried out by placing the specimen close to the lens. The created image passes through the lenses to enlarge and reach the user’s eye. The transparency and size of the cells allow quick penetration of light.

Key Components to a Light Microscopy

There are three components that are involved in light microscopy – magnification, resolution and contrast.

1. Magnification

• The objective lens magnifies objects 100x times.
• The ocular lens magnifies objects 10x times.
• Using the combination of two will magnify the object 1000x times.

2. Resolution

• Besides magnification, a light microscope’s resolution is an equally important component.
• The resolution of the magnified object should be maintained.

3. Contrast

• With due respect to contrast, the object stands out from the background.
• The contrast technique allows organisms to be highlighted and differentiated from other materials.

What are the types of light microscopy?

Microscopes are an integral part of modern technology. With the evolution of microbiology, specimens are viewed with the help of these types of light microscopy.

1. Bright-field Light Microscope

Also acknowledged as a compound light microscope, it is one of the simplest optical microscopy techniques. The standard microscopy is used for daily research of simple diagnostics and can accurately create a dark image against a white background. It is used to perceive living cells or fixed specimens. The bright-field light microscope is made of two lenses- an eyepiece and an objective lens (made with six or more glasses). With the correct usage, a high-resolution image is produced.

The application of a bright-field light microscope is widely used in microbiology. It can be utilised to view live and fixed specimens which have been stained. Basic bacteria cells can be identified easily.

2. Phase Contrast Light Microscope

Phase-contrast light microscopy is a technique used to make unstained living cells visible. These biological specimens practically absorb no light, due to which they may appear transparent with a brightfield microscope. These cells will have a rich view with phase-contrast by appearing illuminated. The principle of this type of light microscopy works on transforming a specimen into an amplitude image. Once that’s done, it can be clearly viewed.

Application of a phase-contrast light microscope is used to identify animal and plant cells. Microbial elements such as bacteria endospores can also be detected. The technique is also widely used to discern the living cells in tissue culture and keep a check on the growth.

3. Dark Field Light Microscope

The dark field light microscope is used to illuminate living unstained cells. It is similar to a phase-contrast microscope which makes the sample brightly lit against a dark background, and that’s how the name dark field is derived. Most of the light is reflected away from the camera. This type of light microscopy places a condenser lens and a darkfield stop to scatter the beam of light entering the specimen’s objective. To do so, an opaque disc is set down under the condenser lens.

Application of a dark field light microscope is used to view the internal organs of large cells and identify distinctive shapes. The technique helps study marine organisms such as insects, algae and yeast.

4. Fluorescent Light Microscope

A fluorescent light microscope is thoroughly different from those mentioned earlier. The aforestated types of light microscopy create an image once the light is transmitted through the cells. The fluorescent light microscope sheds light by adding a dye molecule to the specimen. It uses a high-intensity light source and stimulates the dye molecule when absorbs light energy. The trapped energy is then released as light. The liberated illuminated energy has a long wavelength and thereby produces a fluorochrome labelled image. The microscope uncovers the cells to the light to form an image.

Application of a fluorescent light microscope is used to view bacteria cells and identify particular antibodies against bacterial pathogens. The fluorescent microscope also recognises and observes microorganisms and identifies the difference between living and dead bacteria.

Advantages of Optical Microscopy (Light Microscopy)

After knowing the ins and outs of what is an optical microscope, here are some lesser-known advantages to know of.

• It imparts an elevated observational quality.
• The microscopes are light in weight.
• An entry-level can be used easily, even by a student.
• They are not affected by electromagnetic fields.
• Through a light microscope, one can observe every structure of a living organism.
• Maintaining it is easy.
• It is adjustable as per the user.
• The intensity of a light microscope can create a long wavelength.
• The specimen’s original colour can be viewed.
• Dead organisms can also be scanned.
• In the field of biology, it is one of the most invasive techniques to look at living organisms.

Application of Light Microscopy in Biology

Light microscopes play a mammoth part in today’s biology. Here’s how the application of it is obliging.

• Biologists can detect details at a cellular level and also comprehend about building blocks of organisms.
• With a light microscope, real-time movements of organisms can be noticed.
• Biologists can also study life-threatening diseases like AIDS and cancer to find a cure.
• In student life, one can understand the real cells and the supporting structure.
• Mingeraoligsts also make use of light microscopy for sample preparations.
• The technique is easy to learn but hard to master in the medical field.
• Light microscopy is used in pathology labs to identify any disease.
• It can inspect the space and time related to the dynamics of molecules.
• Small elements like nanostructures can be identified easily.
• The application of light microscopy is also useful in metallurgy, chemistry and gemmology.
• It is widely used in tissue culture research for cell testing.

One Last Thought:

The scope of microbiology is expeditiously growing in India. Light microscopy can significantly mark the pharma industry, agriculture sector, research organisations, environmental agencies, chemical industry, beverages department and laboratories.

With a major in sustainability, you can excel at life sciences and closely comprehend environmental, food production and ecosystem problems. Atria university adopts an unconventional education structure and gives students an opportunity to get involved in a signature project to study everything from cells to organisms. Once you enrol for the program, you can examine the multicellular life forms from single cells and uncover the principles of cellular organisations and communication. Dissect, image and theorise. The project is designed to provide a hands-on experience.