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Friday, 20 May 2016

Microscope

The first microscope to be developed was the optical microscope. The Dutch spectacle-maker Zacharias Janssen invented the first microscope in 1590, although it was then regarded as a novelty rather than a revolution in science. These earliest microscopes had only one lens and are called simple microscopes.


Reproduction of Zacharias Janssen's early microscope 

Compound microscopes have at least two lenses. In a compound microscope, the lens closer to the eye is called the eyepiece. The lens at the other end is called the objective. Evidence points to the first compound microscope appearing in the Netherlands by the 1620s,

German papal doctor and botanist Giovanni Faber coined the name microscope for Galileo Galilei's compound microscope in 1625  (Galileo had called it the "occhiolino" or "little eye"). Faber came up with the name from the Greek words μικρόν (micron) meaning "small", and σκοπεῖν (skopein) meaning "to look at", a name meant to be analogous with "telescope."

When the British polymath Robert Hooke (July 28, 1635 – March 3, 1703) published his 1665 masterpiece, Micrographia, people were astounded by its depictions of the miniature world. Samuel Pepys called it "the most ingenious book that I ever read in my life". Until then, few people knew that fleas had hairy legs or that plants comprised cells (Hooke coined the term "cell").

The hand-crafted, leather and gold-tooled microscope Hooke used to make the observations for Micrographia, originally constructed by Christopher White in London, is on display at the National Museum of Health and Medicine in Washington, DC.

Hooke's microscope

Antonie van Leeuwenhoek (1632–1724) is credited with bringing the microscope to the attention of biologists, even though simple magnifying lenses were already being produced in the 16th century. Van Leeuwenhoek's home-made microscopes were simple microscopes, with a single very small, yet strong lens. They were awkward in use, but enabled van Leeuwenhoek to see detailed images.

The early compound microscopes were optically poor; much of the best work in the mid 17th century was done using a single lens rather than a compound system.

Dutchman Christiaan Huygens developed a simple two-lens ocular system in the late 17th century that was achromatically corrected, and therefore a huge step forward in microscope development. The Huygens ocular is still being produced to this day, but suffers from a small field size, and other minor disadvantages.

Joseph Jackson Lister (1786-1869)’s design of a microscope lens which did not distort colors opened the way for the microscope to be used as a serious scientific tool.

Joseph Jackson Lister

Robert Koch (1843–1910) began studying bits of matter through a magnifying glass. It was only when he received a microscope from his wife for his 28th birthday and then began his study of anthrax and was able to establish that it was microorganisms can cause disease.

In 1846, the American paleontologist  Joseph Leidy (1823-1891) became the first person to solve a murder using a microscope. He examined blood on the shirt of the accused and determined it was human, not chicken blood, as the suspect claimed.

The electron microscope uses electrons rather than light to generate the image. German physicist Ernst Ruska  (December 25, 1906 – May 27, 1988)  demonstrated in 1931 that a magnetic coil could act as an electron lens, and used several coils in a series to build the first electron microscope in 1933.

Electron microscope

Working at Siemens Ernst Ruska, developed the first commercial transmission electron microscope in 1939. Major scientific conferences on electron microscopy started being held in the 1950s.

Ruska won the Nobel Prize in Physics in 1986 for his work in electron optics, including the design of the first electron microscope.

Source The Independent

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