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Who Invented the Microscope?
A microscope is an instrument used to see tiny things which are otherwise invisible to the naked eye. The word microscope is a combination of two Greek words: mikros "small" and skopos "watcher."
An object will appear larger the closer it is moves to the human eye. But when it is less than 10 inches, it becomes unfocused. However if a simple convex lens is placed between the eye and the object, it can be brought closer than 10 inches and still remain in focus.
Ordinary magnifying glasses are basically a simple microscope, and they have been used as such since remote times. So when we speak of the invention of the microscope, we really mean the "compound microscope." But today when we refer to a "microscope" the compound microscope is the kind we mean.
The technique of using water-filled glass spheres to produce magnification was known to the Greeks in the 2nd century B.C. In the 10th and 11th centuries A.D. the Arab scientist Alhazen studied the magnification produced by segments of glass spheres.
The first compound microscope was devised by a Dutch maker of spectacles, Zacharias Janssen, in 1590. The first person to make extensive use of the microscope used a simple microscope. He was the Dutch scientist Antony van Leeuwenhoek (1632-1723).
About 1684 the Dutch physicist Christiaan Huygens invented a modern type of twin-lens eyepiece. Important improvements in the compound microscope were made by the English scientist Robert Hooke (1635-1703). Major improvements in microscope lenses were made by the German physicist Ernst Abbe (1840-1905).
The electron microscope was developed by two German scientists, Max Knoll and Ernst Ruska, in 1932. Their work was based on the discovery of electron lenses by another German scientist, Hans Busch.
Leeuwenhoek's lenses, powerful as they were for his time, did not have a great magnification. He used simple magnifiers which he mounted himself. The complicated piece of machinery we call a microscope represents a vast improvement in optical achievements and must be well understood by its users. Many have worked up to the microscope by using hand and pocket lenses to magnify things of interest. This prepares them for the fun of viewing a miniature world through the compound microscope.
To study the quill of a porcupine with the aid of a hand lens so that the effective "barb" on its outer end becomes visible, or to view the pollen baskets of the worker bees can be fascinating. But, the real thrill will come when numbers of tiny creatures suddenly become visible through the compound microscope.
Knowledge of the compound microscope, the name and purpose of each part, is important to the student of microscopy. Starting at the top, you come into contact with the eyepiece, or ocular, which may be on an extension tube of the main tube of the microscope.
At the bottom of the tube are the objectives (a very simple microscope may have only one) which are poised above the stage. There are clips to hold the slide in place on the stage, and a hole in the center through which shines light reflected by a mirror attached above the foot of the microscope. The adjustment knob for raising or lowering the tube is on the microscope arm.
With the aid of the lenses in the microscope, you are actually bringing the object nearer your eye. Depending upon the power of the lenses, you will see the object in various stages of enlargement.
As an example, if the objective magnifies the object 10 diameters- that is, your eye is 10 times nearer to the object - the image it receives is further magnified by the eyepiece which is also 10 times, giving you a magnification of 100 times the object.
Care and skill in handling the microscope are essential. The mechanics of the instrument must be mastered first.