History Of Light Microscopy
Since the time of the Romans, it was realized that certain shapes of glass had properties that could magnify objects. By the year 1300, these early crude lenses were being used as corrective eyeglasses. It wasn't until the late 1500s, however, that the first compound microscopes were developed.
Robert Hooke (1635-1703) was the first to publish results on the microscopy of plants and animals. Using a simple two lens compound microscope, he was able to discern the cells in a thin section of cork. The most famous microbiologist was Antoni van Leeuwenhoek (1632-1723) who, using just a single lens microscope, was able to describe organisms and tissues, such as bacteria and red blood cells, which were previously not known to exist. In his lifetime, Leeuwenhoek built over 400 microscopes, each one specifically designed for one specimen only. The highest resolution he was able to achieve was about 2 micrometers.
By the mid-nineteenth century, significant improvements had been made in the light microscope design, mainly due to refinements in lens grinding techniques. However, most of these lens refinements were the result of trial and error rather than inspired through principles of physics. Ernst Abbé (1840-1905) was the first to apply physical principles to lens design. Combining glasses with different refracting powers into a single lens, he was able to reduce image distortion significantly. Despite these improvements, the ultimate resolution of the light microscope was still limited by the wavelength of light. To resolve finer detail, something with a smaller wavelength than light would have to be used.
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