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Compound Microscope



Invented by : Zacharias & Hans Janssen
Invented in year : 1590

Compound microscope an instrument to see objects too small for the naked eye. Essentially a compound microscope has more than one lens as compared to a simple microscope. Compound microscope is used for many purposes. Modern compound light microscopes, under optimal conditions, can magnify an object from 1000X to 2000X (times) the specimens original diameter. For a microscope to function in an effective manner, a light source is needed to illuminate the object to be seen. That source can be a mirror, or the instrument can be self-illuminating. As light passes through the object, the lens nearest the object, called the objective lens, produces an enlarged image of the object in the primary image angle. The lens that you look into, the eyepiece, acts as a magnifier and produces an enlarged image of the image produced by the objective lens. Microscopes come with different magnifications, like a 10x eyepiece in conjunction with a 40X objective, gives you a magnification factor of 400. The object will be magnified 400 times larger than you can view it with the naked eye.

History

There is a lot of controversy regarding the inventor of compound microscope. Though, there are three contenders - Hans Lippershey, Zacharias Jansen - Hans Janssen and Giovanni Faber who coined the name 'Microscope' for Galileo Galilei's compound microscope in 1625. Galileo used to call it the 'Occhiolino' or 'Little eye'. However, Zacharias Jansen and Hans Janssen are widely regarded as the inventors of  compound microscope. Zacharias Jansen was a Dutch spectacle-maker from Middelburg. He is also known as Zacharias Janssen and Sacharias Jansen. During 1590-1595, zaccharias janssen and his son hans, while experimenting with several lenses in a tube, discovered that nearby objects appeared greatly enlarged. The first compound microscopes produced by the Janssen's was simply a tube with lenses at each end. The magnification of these early scopes ranged from 3X to 9X, depending on the size of the diaphragm openings.

Development in the invention of compound microscope

In 1609, Galileo, father of modern physics and astronomy, heard of these early experiments, worked out the principles of lenses, and made a much better instrument with a focusing device. Few years later in 1667, Robert Hooke studied various object with his microscope and published his results in Micrographia. Among his work were a description of cork and its ability to float in water.

In 1675, Anton van Leeuwenhoek brought the microscope to the attention of biologists. Van Leeuwenhoek's home-made microscopes were very small simple instruments, with a single, yet strong lens. They were awkward in use, but enabled van Leeuwenhoek to see detailed images. It took about 150 years of optical development before the compound microscope was able to provide the same quality image as van Leeuwenhoek's simple microscopes, due to timely difficulties of configuring multiple lenses.

Later in 1830, Joseph Jackson Lister reduced the problem with spherical aberration by showing that several weak lenses used together at certain distances gave good magnification without blurring the image. 48 years later, in 1878, Ernst Abbe formulates a mathematical theory correlating resolution to the wavelength of light. Abbes formula make calculations of maximum resolution in microscopes possible.

In 1903, Richard Zsigmondy developed the ultramicroscope, which was a major achievement in microscopy. It enabled him to study objects below the wavelength of light. He won the noble prize for his achievement. Then in 1932,  Frits Zernike invented the phase-contrast microscope that allowed the study of colourless and transparent biological materials. It earned him the nobel prize in physics.

By 1938, Ernst Ruska developed the electron microscope. The ability to use electrons in microscopy greatly improved the resolution and greatly expands the borders of exploration.

During 1981, Gerd Binnig and Heinrich Rohrer invented the scanning tunneling microscope that gives three-dimensional images of objects down to the atomic level.
In present time digital microscopes are now available which use a CCD camera to examine a sample and the image is shown directly on a computer screen without the need for expensive optics such as eye-pieces. Other microscopic methods which do not use visible light include scanning electron microscopy and transmission electron microscopy.

Role of the invention of compound microscope in the improvement of human life

  • The creation of the compound microscope helped to advance the field of microbiology light years ahead of where it had been only just a few years earlier.
  • It also helped various advancement in the field of science like finding various types of microorganisms which were not visible to the naked eye.
  • Various scientific discoveries further assisted medical science which could now figure out causes of various diseases.
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  Page updated on : 19-Dec-2009  | Total page views : 4045


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