Robert Hooke, the English scientist made a simple microscope in 1665 and famously coined the word "cells" when observing cork through a lens. In 1674, Anton van Leeuwenhoek a Dutch inventor built a single lens simple microscope that enabled him to study what he named "wee beasties" in pond water--microorganisms seen for the first time. In the 18th century, microscopes were improved by combining two types of glass to reduce the halos resulting from refraction or bending of light. In 1872, Joseph Jackson showed that several weak lenses placed in a specific way gave a good magnification and this would eventually lead up to compound microscopes being developed. Ernst Abbe, a German mathematician wrote a mathematical formula allowing for the best resolution in microscopes. In 1932, Frits Zernike invented phase contrast microscopes which are good for observing transparent biological materials. The German scientist, Enrst Ruska in 1931 invented the electron microscope which doesn't use light at all, rather, it depends on a beam of electrons speeded up in a vacuum with a short wavelength that can make it possible to see objects as small as the diameter of an atom. Gerg Binning and Heinrich Rohrer in 1981 developed the scanning tunneling microscope which provides a 3-D image on the atomic level. These gentlemen worked for IBM.