scanning tunneling microscope

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A microscope that scans the surface of a sample with a beam of electrons, causing a narrow channel of tunneling electrons to flow between the sample and the beam, and producing three-dimensional images of atomic topography and structure.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A device used to form an image of the surface of a conductor or semiconductor with atomic resolution.