Beginning as early at the 1930s, scientists were able to see at the nanoscale using instruments such as the scanning electron microscope, the transmission electron microscope, and the field ion microscope. The most recent and notable developments in microscopy are the scanning tunneling microscope and the atomic force microscope.
The electron microscope, first developed by German engineers Ernst Ruska and Max Knoll in the 1930s, uses a particle beam of electrons to illuminate a specimen and create a highly magnified image. Electron microscopes yield much greater resolution than the older light microscopes; they can obtain magnifications of up to 1 million times, while the best light microscopes can magnify an image only about 1,500 times.