For decades, military scientists promised that lasers were the weapons of tomorrow, just around the corner. But the vats of toxic chemicals used to power the lasers made them all-but-useless in a real-life war. So the Pentagon shifted its efforts about five years ago, to solid state, electric-powered lasers, which would be easier to carry into combat. In 2009, one of those lasers hit what’s believed to be battlefield strength, firing pulses of about 100 kilowatts. That’s like 1,000 lightbulbs, shining on exactly the same spot and in the same wavelength.

It was an impressive laboratory feat. It wasn’t something you could to take Afghanistan, however. Nor was there a vehicle that could carry the weapon to war. The laser was big, fragile, and required giant cooling units and generators to keep it blasting. So the Army started last year a “Robust Electric Laser Initiative,” or RELI, to squeeze that laser into something that could fit on a truck — and keep its cool and its power in combat.

The idea is to build a set of rugged modules that can covert 30 percent of their electric power into laser power. Chain four of these 25 kW modules together, and you should have the heart of a working laser weapon. Lockheed Martin, Raytheon, Northrop Grumman, and General Atomics all have introductory design contracts, worth $42 million all told. The final RELI modules are supposed to be done by 2016 or so.