New system developed to test and evaluate high-energy laser weapons

August 17, 2010, Georgia Institute of Technology
With Orlando-based OptiGrate, GTRI senior research scientist David Roberts designed and fabricated a target board that can survive high-energy laser irradiation without changing its properties or significantly affecting the beam. Credit: Georgia Tech Photo: Gary Meek

Technologies for using laser energy to destroy threats at a distance have been in development for many years. Today, these technologies -- known as directed energy weapons -- are maturing to the point of becoming deployable.

High-energy lasers -- one type of directed energy weapon -- can be mounted on aircraft to deliver a large amount of energy to a far-away target at the speed of light, resulting in structural and incendiary damage. These lasers can be powerful enough to destroy cruise missiles, artillery projectiles, rockets and mortar rounds.

Before these weapons can be used in the field, the lasers must be tested and evaluated at test ranges. The power and energy distribution of the high-energy beam must be accurately measured on a target board, with high spatial and temporal resolution.

Before high-energy lasers can be mounted on aircraft to deliver energy powerful enough to destroy cruise missiles and rockets, they must be tested and evaluated at test ranges. The reusable target board shown here enables the power and energy distribution of the high-energy laser beam to be accurately measured with high spatial and temporal resolution. Credit: Georgia Tech Photo: Gary Meek

Researchers at the Georgia Tech Research Institute (GTRI) have developed a system to measure a laser's power and spatial energy distribution simultaneously by directing the laser beam onto a glass target board they designed. Ultimately, the reusable target board and beam diagnostic system will help accelerate the development of such high-energy laser systems and reduce the time required to make them operational for national security purposes.

"The high-energy laser beam delivers its energy to a small spot on the target -- only a couple inches in diameter -- but the intensity is strong enough to melt steel," said GTRI senior research scientist David Roberts. "Our goal was to develop a method for determining how many watts of energy were hitting that area and how the changed over time so that the lasers can be optimized."

GTRI senior research scientist David Roberts developed a system to measure a laser's power and spatial energy distribution simultaneously, which will help accelerate the development of high-energy laser systems and reduce the time required to make them operational for national security purposes. Credit: Georgia Tech Photo: Gary Meek

GTRI teamed with Leon Glebov of Orlando-based OptiGrate to design and fabricate a target board that could survive high-energy without changing its properties or significantly affecting the beam. The researchers selected OptiGrate's handmade photo-thermo-refractive glass -- a sodium-zinc-aluminum-silicate glass doped with silver, cerium and fluorine -- for the target board.

"This glass is unique in that it is transparent, but also photosensitive like film so you can record holograms and other optical structures in the glass, then 'develop' them in a furnace," explained Roberts.

The researchers tweaked the optical characteristics of the glass so that the board would resist degradation and laser damage. OptiGrate also had to create a new mold to produce four-inch by four-inch pieces of the glass -- a size four times larger than OptiGrate had ever made before.

During testing, the four-inch-square target board is secured between a test target and a high-energy laser, and the beam irradiance profile on the board is imaged by a remote camera. The images are then analyzed to provide a contour map showing the power density -- watts per square inch -- at every location where the beam hit the target.

"We can also simultaneously collect power measurements as a function of time with no extra equipment," noted Roberts. "Previously, measuring the total energy delivered by the laser required a ball calorimeter and temperature measurements had to be collected as the laser heated the interior of the ball. Now we can measure the total energy along with the total power and power density anywhere inside the beam more than one hundred times per second."

GTRI's prototype target boards and a high-energy profiling system that uses those boards were delivered to Kirtland Air Force Base's Laser Effects Test Facility in May. The researchers successfully demonstrated them using the facility's 50-kilowatt fiber laser and measured power densities as high as 10,000 watts per square centimeter without damaging the beam profiler.

Scaling the system up to larger target board sizes is possible, according to Roberts.

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1 / 5 (1) Aug 17, 2010
Then all you have to do is to shield your missiles with that isn't it?
not rated yet Aug 17, 2010
Being transparent, it wouldn't actually shield anything.
1 / 5 (1) Aug 17, 2010
So, anyone that acquires or creates "target boards" and flies a dummy airborne object within a "new" high energy laser perimeter, should be able to figure out the specifications of a missile defense system? Even a compact rocket should be able to trigger and take a snap shot of any online system.
not rated yet Aug 18, 2010
That energy must go somewhere else, missiles or rockets are not designed to dissipate those huge amounts of energy and parts of them will melt or burn, with or without that kind of target glass board mounted on them, maybe the target board would be the only thing to survive direct exposure to the laser beam, but that's all.
not rated yet Aug 18, 2010
countermeasures for lasers = Smoke and Mirrors.
not rated yet Aug 18, 2010
Yet another sign indicating the complete obsolescence of EVERYONE's nuclear weapon delivery systems that drove 20th century geopolitics. You can't effectively use nuclear weapons if nothing in the sky can survive. ICBM re-entry vehicles don't stand a chance against laser weapons, and pretty soon everyone will have them. High density Plasma and heavy ion beams defenses aren't far behind, and they are even more powerful.

So what will happen to the stability of the world when air power is obsolete? Missiles, bombers, fighters, nothing will be able to enter a battlefield by air.
not rated yet Aug 18, 2010
Coat a missile with a thin shell of carbon fiber foam and lasers become useless. I have seen a thin carbon fiber mat survive *minutes* of exposure at a beam intensity of around 15MW/m^2
not rated yet Aug 18, 2010
High energy lasers are just the beginning - ABM will become common and nothing can prevent this from occurring. It's a function of energy availability, sensor tech, and computer power. Even a dumb projectile can hit a missile with enough sensor and computer power behind it.

Lasers are just the beginning, with such high powers, harder weapons like Shiva Star may become miniaturized and deployable. Those can't be stopped by a thin film of anything.

I wonder if this will spur the development of meteor weapons, since they can achieve the same energies at impact as nuclear devices, and are almost totally unstoppable upon entry.
not rated yet Aug 22, 2010
Everyone with an equal powerfull lasershield would provide a level playfield to discourage missile attacks, but for offensive purposes ultimately it boils down to who gets the most powerful lasers with the longest effective range, so that you could take out your opponents laser before it shoots at you. This would require huge lasers on planes or from space for close combat support. Rogue states and terrorists without access to this expensive high tech would contemplate stealth delivery tactics (e.g. low sea skimming cruise missile launched from sub in relative proximity of target to lower detection/response time) or in case of terrorists smuggle a nuclear bomb in part across borders
5 / 5 (1) Aug 22, 2010
"You know, I have one simple request. And that is to have sharks with frickin' laser beams attached to their heads!"

Sorry, but after reading some of the comments here, this popped into my head :)

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