The word microscope is derived from the Greek mikros (small) and skopeo (look at). From the dawn of science there has been an interest in being able to look at smaller and smaller details of the world around us. Biologists have wanted to examine the structure of cells, bacteria, viruses, and colloidal particles. Materials scientists have wanted to see inhomogeneities and imperfections in metals, crystals, and ceramics. In geology, the detailed study of rocks, minerals, and fossils on a microscopic scale provides insight into the origins of our planet and its valuable mineral resources.
Nobody knows for certain who invented the microscope. The light microscope probably developed from the Galilean telescope during the 17th century. One of the earliest instruments for seeing very small objects was made by the Dutchman Antony van Leeuwenhoek (1632-1723) and consisted of a powerful convex lens and an adjustable holder for the object being studied. With this remarkably simple microscope, Van Leeuwenhoek may well have been able to magnify objects up to 400x; and with it he discovered protozoa, spermatozoa, and bacteria, and was able to classify red blood cells by shape. The limiting factor in Van Leeuwenhoek's microscope was the single convex lens, remedied later by the addition of a second lens, giving us the compound microscope--the basis of light microscopes today.
In the 18th century, technological innovations and design improvements enabled microscopes to gain popularity with scientists and researchers in all areas of human biology, botany, zoology, geology, and materials science. One hundred years later, in the 1920s, it was discovered that accelerated electrons behave in a vacuum much like light. Furthermore, it was found that electric and magnetic fields could be used to shape the paths followed by electrons similar to the way glass lenses are used to bend and focus visible light. Ernst Ruska at the University of Berlin, along with Max Knoll, combined these characteristics and built the first transmission electron microscope (TEM) in 1931, for which Ruska was awarded the Nobel Prize for Physics in 1986.
On December 29th, 1959, the noted physicist Richard Feynmanissued an invitation to scientists to enter a new field of discovery with his lecture entitled "There's Plenty of Room at the Bottom," delivered at the annual meeting of the American Physical Society at the California Institute of Technology (Caltech). Many would credit this talk as the genesis of the modern field of nanotechnology, the science of manipulating molecular- and atomic-level structures to engineer microscopic devices.
Next: Types of Microscopes