Number 50 (Story #4), October 3, 1991 by Phillip F. Schewe and Ben Stein BLUE LIGHT FROM A ZINC SELENIDE LASER DIODE , the shortest-wavelength light (490 nm) yet produced by a solid-state structure, has been demonstrated by scientists at 3M Company (Applied Physics Letters, 9 Sept. 1991). Before blue/green lasers can be used commercially, several technical problems must be overcome, in this case a low energy-into-light conversion efficiency and overheating. (Science News, 21 Sept. 1991.)