10 Types of Microscopes used in Biological Science

What is a Microscope?

A microscope is an instrument used to view objects or specimens that are too small to be seen with the naked eye. It uses lenses or a series of lenses to magnify the image of the object, allowing us to see details that would otherwise be invisible.

Microscopes come in many types and sizes, from simple handheld magnifying glasses to complex electron microscopes used to see the ultrastructure of the cell.

In this post let us discuss ten microscopes used in biological science.

Types of Microscope used in Biology

1. Simple Microscope

uses a single convex lens to magnify an object.
It includes magnifying glasses and dissection microscope used to study the morphology of plants and animals

Limitations:

Low magnification Only
used to see morphology because of low magnification.

You can watch our summary video for better understanding

2. Compound Microscope

A compound microscope is an optical instrument that uses two or more lenses to magnify small objects.

How Compound Microscope works?

It consists of an objective lens and an eyepiece lens that work together to produce a magnified image of the specimen. The objective lens is located close to the specimen and produces a real, inverted image, which is then magnified by the eyepiece lens. The magnification of a compound microscope is the product of the magnifications of the objective and eyepiece lenses.

Maximum magnification is 1000 X. Compound microscopes are commonly used in biology to observe cells, bacteria etc.

Limitations:

Thin stained section required
Low resolution and image contrast
Cannot observe live specimens
Maximum Magnification 1000X

3. Dark field microscope

A dark field microscope produces a bright image of the specimen against a dark background.
used for observing live, unstained biological specimens.

How Dark field microscope works?

The dark field technique works by illuminating the specimen with a cone of light that is directed at an angle, causing light to scatter off the specimen and enter the objective lens at an oblique angle. This scattered light is then magnified to produce a bright image against a dark background.

Dark field microscopy is commonly used in microbiology to visualize bacteria, parasites, and other transparent microorganisms.

Limitations

Limited to viewing transparent specimen
Cannot view stained specimen
Cannot view thick specimen

4. Phase contrast microscope

A phase contrast microscope is a type of microscope that enhances the contrast of transparent and colorless samples.
view live specimens with low contrast by amplifying differences in refractive index.

How Phase contrast microscope works?

2 specific microscope components are condenser annulus and objective phase plate to create a phase shift of light that results in an image with greater contrast. The phase plate converts the phase shift into an intensity shift, which is then detected by the microscope's objective lens and converted into contrast that enhances the visibility of the specimen's features.

It was invented by Dutch physicist Frits Zernike in the 1930s

Limitations

Low resolution
Causes halo effect

5. Differential Interference Contrast Microscope

also called as Nomarski microscopy
used to observe high contrast images of live transparent samples

How DIC Microscope works?

It works by transforming differences in the refractive index of the specimen into contrast variations. It works by splitting a polarized light beam into two beams that pass through the sample at slightly different angles, creating interference patterns resulting in a 3D-like image with high resolution and clarity.

Limitations

3D image may not be accurate
More expensive

6. Fluorescence Microscope

Used to view fluorescently-labeled live specimens in high contrast.

How Fluorescence Microscope Works?

It uses fluorescence to produce an image. It works by exciting fluorescent molecules in a sample with a specific wavelength of light, causing them to emit light of a different wavelength. The emitted light is then detected by the microscope and used to generate an image with high spatial resolution.

Widely used to see specific cell structures or proteins

Limitations

Need for fluorescent tagging of specimens
expensive

7. Confocal Microscope

A specific fluorescent microscope that allows obtaining 3D images of the live sample in real time with good resolution.

How Confocal Microscope Works?

It uses a laser to illuminate the specimen and a pinhole to eliminate out-of-focus light. This creates a sharper, clearer image with greater depth resolution than traditional fluorescence microscopes.

Limitations

limited number of excitation wavelengths available with common lasers
Expensive
need for fluorescent tagging of specimens.

8. Scanning Electron Microscopes

Scanning electron microscopes (SEMs) are powerful tools used to obtain high-resolution images of the surfaces of solid objects.

How SEM works?

They work by scanning a beam of electrons over the surface of the sample, which interacts with the atoms and produces signals that are used to generate an image. In SEM, scattered secondary electrons are used to generate an image.

View and analyze surfaces at high magnification by scanning a focused beam of electrons over the surface of a sample.
magnifying samples up to 2 million times with high depth of focus
Less expensive than TEM

Limitations

cannot view living specimens
Low resolution
Skilled operators
Expensive

9. Transmission Electron microscopes

Transmission electron microscopes (TEMs) are powerful tools used to observe the ultrastructure of cells and tissues at high magnifications and resolutions.

How TEM works?

TEMs use a beam of electrons to illuminate a thin sample, the transmitted primary electrons is used to generate an image of high magnification and resolution.

Subcellular components such as organelles, viruses, and macromolecules.
10-50 million times magnification

Limitations

Require extremely thin samples
Cannot view living specimens (less than 150nm)
Skilled operators, Expensive

10. Scanning Transmission Electron Microscope

A scanning transmission electron microscope (STEM) is a type of electron microscope that is a combination of SEM and TEM.
The STEM works by passing a beam of electrons through a thin sample, which then scatters the electrons and produces an image.
TEM is updated to STEM by an addition of a system that scans a focused beam across the specimen to form the image.
produce high-resolution images of thin samples

Limitations