Ernst August Friedrich Ruska (German pronunciation: [ɛʁnst ˈʁʊskaː] ⓘ; 25 December 1906 – 27 May 1988)[1] was a German physicist who won the Nobel Prize in Physics in 1986 for his work in electron optics, including the design of the first electron microscope.

He was educated at the Technical University of Munich from 1925 to 1927 and then entered Technische Hochschule Berlin (now Technische Universität Berlin), where he posited that microscopes using electrons, with wavelengths 1000 times shorter than those of light, could provide a more detailed picture of an object than a microscope utilizing light, in which magnification is limited by the size of the wavelengths.

As well as developing the technology of electron microscopy while at Siemens, Ruska also worked at other scientific institutions, and encouraged Siemens to set up a laboratory for visiting researchers, which was initially headed by Ruska's brother Helmut, a medical doctor who developed the use of the electron microscope for medical and biological applications.

Concurrently, he served at the institute and as professor at Technische Universität Berlin from 1957 until his retirement in 1974.

[3] In 1986, he was awarded half of the Nobel Prize in Physics for his many achievements in electron optics; Gerd Binnig and Heinrich Rohrer won a quarter each for their design of the scanning tunneling microscope.