Lesson Plan - Get It!
How do you turn the image on the left (below) into the image on the right? With a compound microscope!
What is a compound microscope?
A compound microscope consists of two or more double convex lenses fixed in the two ends of a hollow cylinder.
Who invented the compound microscope?
As far back as the first century, Romans discovered that clear glass, when held up to or over an object, had the strange quality of making the object appear larger.
This discovery led to much experimentation during the centuries that followed, and there are still disputes about who should be rightfully credited with the invention of the very first compound microscope.
It was not until the 1590s that a father and son pair of Dutch eyeglass makers, Zacharias and Hans Jansen, began to really experiment with the glass lenses. They put several lenses in a tube and made an intriguing discovery: The object near the end of the tube appeared to be greatly enlarged, much larger than any image a magnifying glass that existed at the time could produce!
They began to sell these "microscopes" as novelty items. The scientific community saw no real use for them because the maximum magnification reached only 9x, and the images were said to have been blurry, at best.
A century later, another Dutchman, this time a draper and scientist named Anton van Leeuwenhoek, achieved greater success than the Jansen family by developing ways to make the lenses more clear.
He also found ways to use more lenses within a single microscope. He accomplished this by grinding and polishing five hundred and fifty lenses to make his new lens tube that had a magnifying power of 270x and could view objects one millionth of a meter in size (other microscopes of the period could only achieve a maximum of 50x magnification).
Van Leeuwenhoek made many biological discoveries using his microscopes. He was the first to see and describe bacteria, yeast plants, the microcosm of life in a single drop of water, and the circulation of blood corpuscles in capillaries.
Van Leewenhoek's work was verified and further developed by English scientist Robert Hooke, who published the first work of microscopic studies, Micrographia, in 1665. Robert Hooke's detailed work, that included his own illustrations, furthered study in the field of microbiology in England and advanced biological science as a whole.
During the 350 plus years that have passed since Hooke made his discoveries — such as viewing cells of a piece of cork, and using thin slices of an object to obtain the best view — the compound microscope has evolved to allow us to see things in our homes, classrooms, and laboratories that humans once never thought possible.
The compound microscope also inspired other modern advancements in microbiology, including the electron microscope that allows humans to view nanoparticles!
How does a compound microscope work?
Watch the video, How to properly use a compound light microscope (below):
Main parts and functions of a typical compound microscope:
- Objective lens - magnifies the image on the slide
- Eyepiece - allows you to see the object and also magnifies the image
- Mirror - reflects light from another source through the image being observed
- Adjustment knob - allows you to focus the image, or make it more clear, so it can be easily seen
- Stage - holds a slide containing the object to be viewed
- Stage clips - secure the slide on the stage