Boeing (NYSE:BA) is building a laser gun for the U.S. Marine Corps.

No, not that ray gun you see above -- that was the U.S. Air Force Airborne Laser. And no, we're not talking about Boeing's Advanced Tactical Laser or its Laser Avenger projects, either. Respectively, those weapons systems require anything from the size of a Boeing 747 to a small tank to lug them around.

Boeing's newest laser weapon system, in contrast, is small enough to be transported by hand.

Well, by a few hands at least. According to a Boeing representative, the company's new Compact Laser Weapon System (LWS) breaks down into four parts, each transportable by one or two Marines. Boeing says these components include:

a battery

a water-cooled chiller

a commercially available fiber laser

an upgraded beam director, weighing 40% less than a previous model.

In total, the system weighs about 650 pounds and would probably be operated by a squad of eight to 12 soldiers or Marines.

Able to be assembled in just 15 minutes, LWS is capable of generating an energy beam of up to 10 kilowatts that can, depending on the power level, be used to acquire, track, and identify a target -- or even destroy it -- at ranges of at least 22 miles. The weapon is designed specifically to track and attack moving aerial targets such as incoming artillery rounds, and low-flying aircraft and unmanned aerial vehicles.

U.S. Special Operations forces are currently testing LWS, with "multiple" branches of the U.S. military expressing interest -- and no wonder.

According to Boeing, a laser gun such as LWS offers the military a "low cost per shot and an infinite magazine" -- both very attractive attributes. Indeed, in a press release, Boeing observed that "with a steady power supply, the Compact LWS can fire continuously." Such a weapon, once operational, might be used to sweep a battlefield, destroying everything it contacts, making it a significant force multiplier for dismounted infantry units.

What Boeing's new laser gun means to investors

As one of the smallest laser weapons currently in development, LWS could turn into a pretty big force multiplier for Boeing's profits, too. According to a recent study by MicroMarket Monitor, the market for directed energy weapons in the U.S., including research and development funding, hit $3.1 billion in 2013. That number is expected to more than double (to $8.1 billion) by 2018, implying a long-term annual growth rate of 21.5% -- nearly twice the 12% profits growth rate that analysts project for Boeing.

Perhaps more important, Pentagon spending on laser weapons research, development, and -- eventually -- purchases -- holds the potential to reverse declines in revenue at Boeing's defense businesses. According to S&P Capital IQ, sales at Boeing's Network and Space Systems division (which includes lasers research) dropped 6% last year from 2013 levels. Military Aircraft, Boeing's most obviously bellicose division, saw revenues slump 12% in the same period.

Should Boeing capture even just a 25% share of Pentagon-directed energy spending, however (a not unreasonable goal, given how few major defense contractors we have left), these revenues could replace essentially all revenue declines Boeing Defense has suffered over the past year. Assuming steady 9.3% profit margins, a 25% share of the $8.1 billion laser weapons market in 2018 could potentially produce as much as $750 million in operating profit for Boeing -- amounting to 10% of the company's current operating profitability.

In short, Boeing's new Compact Laser Weapon System may be designed for easy portability and small size. The profits, however, could turn out to be very big indeed.