Microscopes are amazing tools that have enabled man to make new scientific discoveries, diagnose and treat human disease, as well as make intricate things that require powerful magnification, resolution, and illumination.
The uses of optical microscopes are almost endless, but they weren’t invented overnight. In fact, they have a long and vibrant history involving numerous significant milestones and innovations. So where did it all start?
Since time began, man has imagined what it would be like to see things beyond the naked eye. The exact time at which man started to use lenses is unknown, but there is evidence that for over 2000 years it has been known that glass makes light bend.
In the 2nd Century BC Claudius Ptolemy documented a stick seeming to bend when submerged in water. In 50-68 AD Emperor Nero used emeralds to watch gladiators, and while it is not known who or when spectacles were first invented, it is known that lenses were first used for spectacles in Italy in the late 13th Century.
Development of the First Microscopes in the 17th Century
In the 1590’s, Zacharias Janssen and his father Hans began to use microscope lenses for the first time. They made a very basic microscope consisting of lenses within a tube and observed that the object at the end of the tube appeared enlarged. Although this wasn’t a working microscope, it certainly paved the way for new innovations.
In 1609 Galileo Galilei heard of this interesting innovation and created a version of a compound microscope with a convex lens and a concave lens, and a tripod to hold the tool in a vertical position for viewing samples.
In 1625 it was Galileo’s friend, Giovanni Faber, who is thought to have created the term ‘microscope’ from the Greek words ‘micron’ (small) and ‘skopein’ (to look at) for this new scientific tool.
In 1665 Robert Hooke, an Englishman with a broad interest in the sciences, published Micrographia, where he describes and illustrates insects and plants that he observed through a microscope.
In this publication he was the first scientist to use the word “cell” after observing that the structure of cavities in cork resembled honeycomb cells.
Hooke is also attributed to using the first microscope with three lenses, a design which is still used today.
Antony Van Leeuwenhoek, born in the Netherlands, was a self-taught scientist who created a very simple microscope with one high quality lens that achieved the highest magnification so far at a power of x270. This was a very useful microscope with which, in the 1670’s, he observed bacteria for the first time. He made many other observations of living cells which were published in the Philosophical Transactions of the Royal Society of London.
Over the next 200 years developments in microscopy were slow due to the difficulties of producing lenses that provided clear, unblurred images. The spherical shape of the lens meant that some parts of the object were clear while other parts of the object were blurry.
An effective stable light source was also an issue in the development of microscopes. The early microscopists used oil lamps and natural sunlight as their source. Through the 19th century “light bulbs” were gradually developed to a point where they could be used in microscopes.
Modern Microscopes
In the late 1800’s microscope design improved greatly due to the work of the German company Ziess, Ernst Abbe, Otto Schott, and August Koehler.
These individuals solved many of the barriers with older microscopes giving rise to new, super powerful microscopes that had better optics and lighting than ever before, being able to achieve powerful magnification and resolution.
In 1902 Frederick E. Ives developed binocular eyepieces, and in 1935 the Carl Zeiss laboratories developed phase contrast microscopy, leading to the best optical microscopes to date.
All microscopes are limited by resolution, and due to the nature of light itself, resolution and magnification are limited. To overcome this barrier, the electron microscope was developed.
The electron microscope replaces light photons with an electron beam which has led to magnifications of x1,000,000 and resolution of less than 2nm, which is an incredible feat.