An anonymous reader writes "Laser guns and other 'directed energy weapons' have remained in sci-fi lore because of their inefficiency, bulkiness, and poor beam quality. Now an MIT Lincoln Lab spinoff called TeraDiode is developing a diode laser that uses 'wavelength beam combining' to create what it calls the brightest and most powerful laser of its kind. The two-year-old company, backed by $3 million from the U.S. Department of Defense and $4 million from venture capitalists, is working on a compact airborne laser system for planes to shoot down heat-seeking missiles. Eventually, the lasers could be mounted on a tank or ship to destroy enemy UAVs or even incoming artillery shells. That's still at least three to five years away, but with advances in semiconductor lasers there seems to be quite a renewed interest in weaponry."