Posted by Fred Koenig on Oct 10th 2022

How Does a Microscope Work?

The very first microscope was invented in the late 1500s, and although technology and computers have advanced the field of microscopy today, some of the basic principles of how a microscope works have stayed the same.

What Is a Microscope

In the most basic sense, a microscope is a tool that’s used to see objects that are too small to be seen by the eye alone. There are many things happening in the world around us and inside of us that we simply can’t see, although we know that they happen. Blood cells move through the body carrying nutrients and oxygen, but without a microscope, we can’t see those individual blood cells.

Because microscopes are so useful, they’ve become an essential tool in many fields of science and have helped us understand how the world works. But how do microscopes work, and are they all the same?

How Does a Microscope Work

The very first microscopes weren’t very effective, but they’re a good illustration of how a microscope works. They were created by opticians who were used to grinding glass into lenses for people who needed eyeglasses.

These eyeglass makers realized that if they put one lens at the bottom of a tube and one at the top, they could use the power of both lenses to see tiny objects more clearly. These original microscopes were the first examples of compound microscopes, which are microscopes that use more than one lens to view objects. An even more basic microscope is a single convex lens, which we call a magnifying glass.

In a basic compound microscope, the lens at the bottom of the tube which is closest to the object is the objective lens. This lens takes the light rays that bounce off the object and spreads them apart through a convex lens so they appear bigger. When they appear bigger, we can see them in greater detail than we could without the aid of the lenses.

At the top of the compound microscope is another lens which is called the eyepiece. This lens also magnifies the image coming from the objective lens to give you a more detailed and clearer view of the subject.

While two lenses are necessary for a basic compound microscope to work, a light source is also a key factor. Many microscopes today have their own light sources, but a mirror behind and below the objective lens makes a great light source that can be angled to hit the object precisely.

Detailed Steps of How a Microscope Works

That’s the basic premise behind a microscope; it’s pretty simple with two lenses and a light source. Let’s look at it one step at a time to further understand what’s happening. We’ll use a basic compound microscope with two lenses to continue the explanation.

  • The specimen is placed on a glass slide, usually with another piece of glass over it to prevent it from moving.
  • The specimen slide is slid onto the tray, which typically has metal clips to hold it in place.
  • Below the tray is a mirror, and light from the room hits the mirror and bounces up through a hole in the tray, which is now holding your specimen. The light moves through the specimen and through the objective lens at the base of the tube portion of the microscope.
  • Once passing through the objective lens, the image has had its first magnification. It should be noted that there may be several lenses working together to form the objective lens. It’s not always just one lens.
  • Moving through the objective lens(es), the light then travels up to the eyepiece, which works like a magnifying glass to further increase the visible size of the specimen.
  • Finally, you place your eye on or above the eyepiece and view the image.
  • Throughout the microscope, there may be wheels that help you adjust the positioning of the lenses to sharpen your view and fine-tune the focus.

Other Types of Microscopes

The basics of how a compound microscope works are the same ones that are used in other microscopes. Compound microscopes are still a very important and powerful tool, and they’re used regularly, but there are some advances that have occurred in the more than 400 years since the first microscope, and we have some other options available.

  • Electron microscope: These microscopes get their illumination from a beam of accelerated electrons. This creates a very high resolution of images that are very minuscule.
  • Stereo microscope. A stereo microscope creates a three-dimensional image by taking advantage of your two eyes. These microscopes are sometimes called dissecting microscopes and they feature one eyepiece and objective lens for each eye, giving you that natural 3D view that you have from your own eyes.
  • Inverted microscopes: These microscopes usually have biological or metallurgical uses. Inverted microscopes use a fixed stage for the specimen and then use an objective lens that rests under the stage for illumination and view from below. Some inverted microscopes allow the user to move the objective lens so the specimen can be viewed from many different angles.
  • Digital microscopes: Digital microscopes take advantage of digital cameras to take pictures or project the specimen onto a screen for viewing. This allows for a more detailed view that can be seen by multiple people at once. It can also be easily captured for future reference.
  • Polarizing microscopes: One popular microscope today is a polarizing microscope which takes advantage of the vibrating effect of light waves and focuses those vibrations for a polarized light source. Manipulating polarized light leads to birefringence or double refraction; this is useful as different objects react differently to birefringence, providing information on what the inner structure of the specimen is.

These are a few of the more common microscopes available, but there are many more to choose from. The field of microscopy has become very specialized, allowing for detailed analysis in a variety of professions. If you’re interested in purchasing a microscope, connect with New York Microscope Company to find just the right microscope for your needs and budget.