Different Types of Microscopes & How Each One Functions

By Vern Hee

The first microscope was a tube with a lens on one end and the object on the other. This device only had a magnification of 10. Then in 1597 a Dutch Spectacle maker named Zaccharias Jansseen and his son Han discovered that when you arrange two lenses together a certain way it increases the amount of magnification. This was the birth of the modern microscope, which opened a whole new frontier of science to mankind. Today there are several different types of microscopes available to open up a whole new world.

Compound Microscope

The compound microscope is a very common type of microscope. The term "compound" means more then one lens is used. In the compound microscope you have two lenses. The primary lens is the one closest to the object and then there is the secondary lens, which is furthest from the object. The secondary lens is used to magnify the image of the primary lens. The primary lens is aimed at the condenser, or stage, and this is where the object to be magnified in the form of a slide is placed. A modern compound lens can magnify the original diameter of specimens 1000x to 2000x. The stage is illuminated with a light that shines through a diaphragm. The diaphragm is used to control the amount of light. This microscope is very common today and is still used as a teaching microscope.

The Fluorescence Microscope

The fluorescence microscope is designed to view specimens that fluoresce naturally or glow when treated with fluorescing chemicals. This means the specimens themselves are the light source. There are many materials that glow naturally, such as some chlorophyll and some minerals. They just need to be illuminated by a specific wavelength to make them glow. For specimens that do not glow naturally, they are treated with a fluorophore. The treated and non-treated specimens are then irradiated with a specific wavelength of light. This is absorbed by the specimens and causes them to emit a light of longer wavelengths. This is a different color then the absorbed light. The microscope then amplifies the light radiated by the specimen. The light is then run through filters geared toward a specific wavelength, and an image is produced on a dark background.

Transmission Electron Microscope

Electron microscopes are instruments that use high energy electrons to examine objects that are beyond the scope of the naked eye. An electron microscope can obtain the topography of an object, which is its surface features, determine its morphology or shape and size of an object, determine the composition of the object and finally tell a scientist how the atoms are arranged in an object. This microscope works like a light microscope but instead of light, a beam of electrons is used. The beam of accelerated electrons is focused on the specimen using an electron gun that is powered by several million volts. The specimen to be viewed is in a vacuum chamber. The electrons bombard and pass through the image, where they are captured by an electron magnet that bends the light to produce a photo or image on a screen. The bouncing of the electrons off of the sample produces reactions. The various reactions are captured and transformed into an image by the microscope.This type is the most powerful of all electron microscopes. It can magnify something one million times.