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Simple Microscope: Definition, Principle, Parts, And Uses

The beginnings of microscopy dates back to a few hundred years, when the first microscope was invented. This was the simple microscope, a rudimentary imaging device with just enough magnification to enlarge small objects.

Despite its simplicity, simple microscopes are versatile imaging tools that are still used today in a variety of fields and disciplines. Here is a brief guide on the definition, history, mechanisms, principles, parts, and uses of a simple microscope.

What is a simple microscope?

A simple microscope is essentially a magnifying glass made of a single convex lens with a short focal length, which magnifies the object through angular magnification, thus producing an erect virtual image of the object near the lens. 

It’s the most elementary form of microscopy, dating back as far as the 14th century.

The lens of a simple microscope is interchangeably referred to as a loupe, and is typically used as an eyepiece for other types of simple magnification devices such as compound microscopes, telescopes, and reading glasses. 


Retro simple microscopeThe first simple microscope was invented by a pair of Italian spectacle makers in the year 1590. It had a magnification power of 9x, and a really poor resolution, but it was since developed into much more sophisticated devices in the following years.

Before all this, however, the principles of magnification and microscopy dates back to thousands of years ago, when light refraction was first observed. Fast forward a few hundred years, glass was invented in the 1st century.

This was used for a variety of purposes, from simple magnification, to producing fire, and even aiding surgical operations. Then, it was later on developed into magnifying glasses around the 13th to 14th century.

How does a simple microscope work?

Simple microscopes make use of a biconvex lens to magnify the image of a specimen. Nowadays, these lenses often consist of two glass elements with color correction abilities. The closer the object is to the lens, the larger the magnified image becomes.

A light source directs a certain amount of light to pass through the specimen, then through the lens. For a better image resolution, the size and intensity of the light can be modified through the microscope’s condenser and diaphragm.

This works for thin and semi-transparent specimens in which light can easily pass through with minimal absorption of the specimen. It can also be stained to improve its contrast and therefore show more detail.


Since a simple microscope only makes use of one objective lens, its magnification capability is greatly limited. In fact, most simple microscopes only have a 10x magnification power.

The formula for calculating the magnifying power of a simple microscope is: M  = 1 + D/F, where D is the least distance of distinct vision, and F is the focal length of the convex lens. The shorter the focal length of the lens, the higher the magnifying power of the microscope.

In terms of clarity and resolution, however, this largely depends on the contrast of the specimen, as well as whether there are any aberrations in the lens. The contour of the lens and how it’s used also influence the resulting image resolution.

What are the parts of a simple microscope?

Parts of a simple microscope

Simple microscopes are actually made up of several mechanical and optical components. The mechanical components are what supports the microscope, holds the specimen, and controls some functions of the microscope.

On the other hand, the optical components are what works on enlarging the image of the specimen, as well as allowing the user to view this enlarged image.

Mechanical components

  • Body – the microscope’s body is typically a metal stand with an arm that supports the lens tube connecting the eyepiece to the lens, and connects it to the base, which is a heavy plate that supports the weight of the microscope and keeps it upright.
  • Stage – the stage is a rectangular metal plate attached to the body and features a circular hole in the middle, called the aperture. This is where the specimen slide is mounted on, and typically has a pair of stage clips to keep the slide in place.
  • Nosepiece – the revolving nosepiece is a turret that holds two or more objective lenses to increase the microscope’s magnification. This is present in modern models of the simple microscope, as well as in compound microscopes.

Optical components

  • Lens – the microscope makes use of an objective biconvex lens to enlarge specimen images. Some simple microscopes feature several objective lenses with varying magnification levels, and these can be moved closer to or farther from the specimen.
  • Eyepiece – on the first simple microscopes, the lens also serves as the eyepiece, but on some modern models, the microscope has a separate optical lens to view the specimen image. Eyepieces with their own magnification are used on compound microscopes.
  • Mirror – simple microscopes typically make use of a mirror as its light source, which works by gathering light from external surroundings and reflecting it onto the specimen. Some microscopes have a dedicated light source that is also adjustable.

What is a simple microscope used for?

While simple microscopes are, well, simple imaging devices, these microscopes still have a variety of uses and applications, from scientific studies like biology, to more practical activities such as jewelry and watchmaking, and in looking at books, cloths, stamps, and engravings. 

A simple microscope is a useful tool in microbiology, as it can be used to view microscopic organisms and other biological specimens such as algae, fungi, protists, and Hydra. It’s also commonly used in dermatology to identify skin diseases, and in pedology to look at soil samples.

More rudimentary versions of the simple microscope are commonly utilized as magnifying glasses, reading glasses, and spectacles.


A simple microscope is a rudimentary magnification device that is capable of visibly enlarging small objects, so they can be viewed and studied in better detail. It was invented in the late 16th century, and is still being widely used today.

Simple microscopes have a wide range of applications in various fields. These microscopes have also served as the foundation for the development and invention of many other types of more sophisticated microscopes.

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