Types of Microscopes
A microscope is an optical instrument used in the laboratory for examining the small objects which we can’t see in the naked eye. There are present different types of microscope, which we are using for different purposes. Microscopes are classified based on their working principle, application.
There are mainly present two types of microscope, such as;
- Simple Microscope
- Compound Microscope
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A. Simple Microscope
- Simple Microscope refers to those microscopes consisting of a single lens to enlarge an object through angular magnification alone, giving the viewer an erect enlarged virtual image.
- These types of microscopes use different types of lense for magnification such as; magnifying glass, loupes, and eyepieces.
- A Simple Microscope is a type of optical Microscope or light Microscope.
- This was the first microscope ever created.
- It was invented by Antony van Leeuwenhoek in the 17th century. He combined a convex lens and a holder for specimens.
Working Principle of simple Microscope
All simple microscopes work on a principle, if you place a tiny object or specimen in front of a simple microscope’s lens within its focus, a virtual, erect and magnified image of the object is formed at the least distance of distinct vision from the eye held close to the lens.
B. Compound Microscope
- A compound microscope is a laboratory instrument with high magnification power, which consists of more than one lens.
- Compound Microscopes are used for the study of structural details of a cell, tissue, or organ in sections.
- A compound microscope can magnify the image of a tiny object up to 1000.
- The term compound means “multiple” or “complex”.
- The compound microscope consists of two lenses including the objective lens (typically 4x, 10x, 40x or 100x) in a rotating nosepiece closer to the specimen, and the eyepiece lens (typically 10x) in the binocular eyepieces.
- A compound binocular microscope is more commonly used today.
- Zacharias Jansen created a compound microscope that used collapsing tubes and produced magnifications up to 9X.
- compound microscopes are generally types of bright field microscope.
Working Principle of Compound Microscope
The compound microscopes are works on the principle that when a tiny specimen to be magnified is placed just beyond the focus of its objective lens, a virtual, inverted and highly magnified image of the object are formed at the least distance of distinct vision from the eye held close to the eyepiece.
Classification of Compound Microscope
Compound Microscope is classified in two categories;
1. Light Microscope
Light Microscope is further classified into four categories such as;
- Bright-field Microscope
- Dark-Field Microscope.
- Phase-contrast Microscope.
- Fluorescent Microscope.
2. Electron Microscope
Electron Microscope is further classified into three categories such as;
- Scanning Microscope
- Transmission Microscope
- Confocal Microscope
1. Light Microscope
Light Microscopes use visible light and magnifying lenses to examine small objects not visible to the naked eye, or in finer detail than the naked eye allows. Magnification, however, is not the most important issue in microscopy.
They are classified in these following groups;
a. Bright-field Microscope
In a bright-field microscope, the specimen appears as dark against the bright background.
They are used in the laboratory for studying the outer structure of microorganisms.
b. Dark-Field Microscope:
In the dark-field microscope, the specimen appears as bright against a dark background.
This microscope is used to distinguish unstained, thin living cells that are not visible under a simple microscope.
c. Phase-contrast Microscope:
Some unpigmented living cells are not visible in the light microscope because it can’t create differences in contrast between cells and water. Only Phase-contrast Microscope can create contrast difference between cell and water that is why these cells only visible in Phase-contrast Microscope
Use for studying the shape and motility of microorganisms.
d .Fluorescent Microscope:
In this type, the specimen is stained with fluorescent dyes and then exposed to ultraviolet rays (UV). Fluorescent dyes will absorb low wavelength light and become excited as a result they will release a high wavelength light. Using this mechanism Fluorescent Microscopes work.
Use in medical laboratories for the identification of pathogens. Also used for localization of specific proteins.
2. Electron Microscope
Electron Microscopes use electrons as a source of illumination. It has a higher resolving power than light microscopes.
There are present different types of electron microscope such as;
a. Scanning Electron Microscope (SEM)
This type of electron microscope produces an image of a specimen by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample.
Used to study the surface area of microorganisms in detail.
b. Transmission Electron Microscope (TEM)
In this microscope, the electron beam is passed through a specimen to form an image. The specimen used for TEM should be 20 to 100 nm thick.
It used to study the internal structure of a specimen.
c. Confocal Microscopy
Confocal Microscope also known as confocal laser scanning microscopy (CLSM) or laser confocal scanning microscopy (LCSM).
This is an optical imaging technique to increase the optical resolution and contrast of a micrograph by means of using a spatial pinhole to block out-of-focus light in image formation.
This microscope Capturing multiple two-dimensional images at different depths in a sample enables the reconstruction of three-dimensional structures (a process known as optical sectioning) within an object.
Confocal Microscopy is used extensively in the scientific and industrial communities and typical applications are in life sciences, semiconductor inspection, and materials science.
Types of Microscopes