A brief history of how the light microscope has developed since the 17th Century to the present day.

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The History, Development and Use of the Light and Electron Microscope

A brief history of how the light microscope has developed since the 17th Century to the present day

A microscope is “an instrument that enables the human eye, by means of a lens or combinations of lenses, to observe enlarged images of tiny objects. It made visible the fascinating details of worlds within worlds.” 1   The earliest simple microscope was a tube with a plate for the object at one end and, at the other, a lens that gave a magnification less than 10 times the actual size. Around 1590 a discovery was made by Zaccharias Janssen and Hans Janssen his son, two Dutch spectacle makers, while they were experimenting with numerous lenses in a tube. They found out that nearby objects were greatly enlarged when looking through the lenses in the tube. Later in 1609 Galileo heard of these experiments and worked on the principles of lenses. After doing so he made an instrument that incorporated a focusing device.

Antony van Leeuwenhoek (1632-1723) of Holland was apprenticed in a linen-draper's shop. He set himself up in business as a draper (a fabric merchant) and at some time before 1668, Antony van Leeuwenhoek learned to grind lenses, made simple microscopes, and began observing with them. He taught himself how to polish and grind lenses. Leeuwenhoek's skill at grinding lenses, together with his naturally acute eyesight and great care in adjusting the lighting where he worked, enabled him to build microscopes that magnified 270 times. He then started to use his microscopes to observe just about anything that could be placed under a microscope; he was the first to see and describe bacteria and the existence of tiny living organisms in a drop of water. During his lifetime he observed many living and non-living things under his Light Microscope and wrote letters to the Royal Society of England and the French Academy, describing what he had seen.

Robert Hooke, of England, confirmed Leeuwenhoek’s findings on the idea of living organisms existing in a drop of water, and modified Leeuwenhoek’s microscope design, by slight improvements. He too observed many things through the light microscope and gave cells their name. Due to his and Leeuwenhoek’s findings, it was established that plants were made of cells.

After Hooke’s design only a few major alterations were made to the light microscope until the middle of the 19th Century, when the American Charles A. Spencer made some outstanding optical equipment, and built himself an industry. His model was modified to little measures, and today’s present day light microscope can magnify things up to 1250 times with ordinary light and 5000 times with blue light. Modern light microscopes can be over 6 feet tall, and are still significant as they can enable the user to view living cells in action, unlike electron microscopes.

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The development of the electron microscope

It was the outstanding work of the German Ernst Ruska (1906-1987) in the early 1930’s, which led to the development of the electron microscope. Ruska had shown in his PhD theory the potential for electrons to be used in a microscope. Backed initially by Max Knoll, he put theory into practice and constructed the first electron microscope in 1933. In this type of a microscope, a high vacuum is required in which electrons can be speeded up so that their wavelength is extremely short, which creates an electron beam. Electro-magnetic lenses focus the ...

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