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 laser beam must be accurately measured on a target board, with high spatial and temporal resolution.
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 energy distribution changed over time so that the lasers can be optimized.”
GTRI teamed with Leon Glebov of Orlando-based OptiGrate to design and fabricate a target board that could survive high-energy laser irradiation 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 laser beam 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.
GTRI research engineer Tim Norwood, GTRI research scientist Nathan Meraz and Georgia Tech mechanical engineering undergraduate student Matthew Vickers also contributed to this research.
This project is supported by U.S. Army Award No. N61339-06-C-0046. The content is solely the responsibility of the principal investigator and does not necessarily represent the official view of the U.S. Army
Abby Vogel Robinson | Newswise Science News
Researchers take next step toward fusion energy
16.11.2017 | Texas A&M University
Desert solar to fuel centuries of air travel
16.11.2017 | SolarPACES
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
17.11.2017 | Physics and Astronomy
17.11.2017 | Health and Medicine
17.11.2017 | Studies and Analyses