Invention of MICROSCOPE (c.1590) (Hans and Sacharias Jensen combine lenses in the first Compound microscope)



 
The earliest microscope was no more than a single small lens that magnified between 6 and 10 times.  Sacharias Jensen and his father, Hans, a lens maker, experimented with combinations of lenses and realized that greater magnification could be obtained by an inversion of the telecope.  Their compound microscope combined a magnifying objective lens (the one closest to the object being investigated) with an eye lens at the opposite end of a tube.  A focusing device was added by the Italian Gallileo Galilei.


The circulation of blood through capillaries was observed by the Italian physiologist Marcello Malpighi (1624-1694).  The popularity of microscopes was greatly enhanced by the publication of Micrographia (1655) by English scientist Robert Hooke.  The Dutchman Anthoni van Leeuwenhoek (1632-1723) used a microscope to count the number of threads in woven cloth, and his refined instrument could magnify 270 times.  Van Leeuwenhoek’s microscope only had a single lens with radius of curvature of roughly 0.7 millimeters.  He was the first to see microorganisms and blood cells.  Of the 500 microscopes manufactured by Van Leeuwenhoek, about ten still survive.

In the eighteenth century, improved glass, coupled with multiple objective lenses with smaller focal lengths that could see much finer detail, led to much better microscopes.  Stages were added so that samples under investigation could be held securely.  The nineteenth century brought the familiar microscope form with its firmly mounted, vibration-free optical tube.
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