How
It Works: The Flying Laser Cannon
Boeing's new laser cannon can melt a hole in a tank from five
miles away and 10,000 feet up—and it’s ready to fly this year
Posted 03.13.2008 at 3:48 pm 26
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Inside the Advanced Tactical Laser : Bob Sauls (Illustration)
Creating a laser
that can melt a soda can in a lab is a finicky enough task. Later this year,
scientists will put a 40,000-pound chemical laser in the belly of a gunship
flying at 300 mph and take aim at targets as far away as five miles. And we’re
not talking aluminum cans. Boeing’s new Advanced Tactical Laser will cook
trucks, tanks, radio stations—the kinds of things hit with missiles and rockets
today. Whereas conventional projectiles can lose sight of their target and be
shot down or deflected, the ATL moves at the speed of light and can strike
several targets in rapid succession.
Last December, Boeing, under contract
from the Department of Defense, installed a $200-million prototype of the laser
into a C-130 at Kirtland Air Force Base in New Mexico in preparation for test
flights this year. From there it will go to the Air Force for more testing, and
it could be in battle within five years.
Precise control over the beam’s aim
allows it to hit a moving target a few inches wide and confine the damage to
that space. The Pentagon hopes such precision will translate into less
collateral damage than even today’s most accurate missiles. Future versions
using different types of lasers could be mounted on smaller vehicles, such as
fighter jets, helicopters and trucks.
How to Melt a Tank in
Three Seconds Or Less
1. Find Your Target
When the C-130 flies within targeting range (up to five miles away), the gunner
aims using a rotating video camera mounted beneath the fuselage. The computer
locks onto the object to continually track it. A second crew member precisely
adjusts the laser beam’s strength—higher power to disable vehicles, lower power
to knock out, say, a small power generator. The gunner hits “fire,” and the
computer takes over from there.
2. Heat Up the Laser
In a fraction of a second, chlorine gas mixes with hydrogen peroxide. The
resulting chemical reaction creates highly energetic oxygen molecules.
Pressurized nitrogen pushes the oxygen through a fine mist of iodine,
transferring the oxygen’s energy to iodine molecules, which shed it in the form
of intense light.
3. Amplify the Beam
The optical resonator bounces this light between mirrors, forcing more iodine molecules
to cough up their photons, further increasing the laser beam’s intensity. From
there, the light travels through a sealed pipe above the weapon’s crew station
and into a chamber called the optical bench. There, sensors determine the
beam’s quality, while mechanically controlled mirrors compensate for movement
of the airplane, vibration and atmospheric conditions. Precise airflow
regulates the chamber’s temperature and humidity, which helps keep the beam
strong.
4. Stand Clear
A kind of reverse telescope called the beam expander inside a retractable,
swiveling pod called the turret widens the beam to 20 inches and aims it. The
laser’s computer determines the distance to the target and adjusts the beam so
it condenses into a focused point at just the right spot. Tracking computers
help make microscopic adjustments to compensate for both the airplane’s and the
target’s movement. A burst of a few seconds’ duration will burn a
several-inch-wide hole in whatever it hits.
FAQ
How
hot is the beam? The laser itself isn’t hot, but it can heat
its target to thousands of degrees.
Does
the laser sear everything in its path? Yes. If a bird
flew into the firing laser’s line of sight— well, no more bird. Fortunately,
the weapon will fire for only a few seconds at a time, minimizing the risk.
Does
it melt its target or just set it aflame?
That depends on what it hits. It will melt metal, but if the target is
combustible, it will burn.