Fraunhofer, Joseph von (17871826), a German optician and physicist. He was the first to make a careful study of the dark lines that appear in the solar spectrum, and these lines (and similar ones from other sources) were named in his honor. By analyzing Fraunhofer lines, scientists later learned to identify elements in the sun and other astronomical bodies.

Fraunhofer began work as a journeyman in an optical workshop in 1806, and quickly advanced as he made original contributions to optical science and developed technically superior telescopes, microscopes, and other optical instruments. In 1814, he devised a diffraction grating for measuring wavelengths of rays of light. In 1823 he became director of the Physics Museum of the Bavarian Academy of Sciences.