Although there is no single inventor of the microscope, in 1595, Zacharias Janssen and his father, Hans, invented the first compound microscope. Both glasses makers, their invention proved that a series of lenses inside a tube creates an enlarged image.
The Janssens' microscope was hand-held and consisted of bi-convex and plano-convex lenses that could magnify images up to 10 times their actual size. In the 1600s, Anton van Leeuwenhoek developed a simple microscope with a more powerful focus and magnification to view microorganisms and cells. Robert Hooke's compound microscope used illumination to observe plant and animal cells, minerals and fossils. In the 1800s, Carl Zeiss, Otto Schott and Ernst Abbe further studied magnification and improved the color accuracy and glass. Ernst Ruska invented the first electron lens in 1931.