Posts from the ‘Laser’ Category

Five holes blasted by Curiosity using its super-awesome laser on some Martian ground. Not only does it shoot, but it can break down the resulting plasma and determine what molecules are present.

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quantumaniac:

First Practical Maser (Microwave Laser) Built

Using spare chemicals, a laser bought on eBay and angst from a late-night argument, physicists have got the world’s first room-temperature microwave laser working. The achievement comes nearly 60 years after the first clunky versions of such devices were built, and could revolutionize communication and space exploration. The work is published this week in Nature.

Before there were lasers, there were microwave lasers, or masers. First conceived in the Soviet Union and the United States during the 1950s, early maser machines were the size of a chest of drawers. They produced only a few nanowatts of power, severely limiting their usefulness.

Because of this impediment, most in the field gave up on masers and moved on to lasers, which use the same principles of physics, but work with optical light instead of microwaves. Lasers are now used in applications ranging from eye surgery to CD players. The poor maser lived on in obscurity. It found only a few niche uses, such as boosting radio signals from distant spacecraft — including NASA’s Curiosity Mars rover. Those masers work only when cooled to less than ten degrees above absolute zero, and even then they are not nearly as powerful as lasers.

Pink power
But Mark Oxborrow, a physicist at the UK National Physical Laboratory in Teddington, wondered whether a crystal containing the organic molecule pentacene might offer a breakthrough. He came across a decade-old publication by Japaneseresearchers suggesting that when the electrons in pentacene are excited by a laser, they configure such that the molecule could work as a maser, possibly even at room temperature.

He borrowed some spare pentacene from a lab at Imperial, and cooked it with another organic molecule known as p-terphenyl. The result was a pink crystal a few centimeters long.

Next, the team needed a powerful laser. Oxborrow located an old medical laser on eBay and drove to a warehouse in north London to pick it up. But the researchers were filled with doubts — the whole thing seemed too easy. Oxborrow admits that he was skittish about the experiment. “For about three days, I could have done it, but I didn’t have the nerve to switch on that button,” he says.

The final impetus came from an argument with his wife. Whereas less well-behaved people might have wallowed in the pub, “I went to the lab as a bit of therapy”, says Oxborrow. “I said, ‘Oh well, what the hell, let’s just try it.” And it worked on the first go.

Excited state
The laser light excited the pentacene molecules to an energy level known as a metastable state. Then a microwave passing through the crystal triggered the molecules to relax, releasing a cascade of microwaves of the same wavelength.

It was the same principle as an optical laser. “The signal that came out of it was huge,” says Oxborrow, about a hundred million times as powerful as an existing maser. Alone in his lab, “I swore a lot and walked around the corridor about five times talking to myself”.

Left: New maser

Right: A Hydrogen Radio Frequency Discharge (early Maser)

ikenbot:

Record-Breaking Laser Hits 500 Trillion Watts

Laser physicists at the Lawrence Livermore National Laboratory have broken the record for the highest-power laser shot with a collection of beams delivering more than 500 trillion watts of peak power.

The National Ignition Facility fired 192 beams at the same time, delivering 1.85 megajoules of ultraviolet laser light to a target a mere two millimeters in diameter.

To put those numbers into perspective, the 500 terawatt figure is 12,500 times greater than the demand for electricity in 2006 in Britain, which averaged out at 40 gigawatts.

“For scientists across the nation and the world who, like ourselves, are actively pursuing fundamental science under extreme conditions and the goal of laboratory fusion ignition, this is a remarkable and exciting achievement,” said Richard Petrasso, senior research scientist and division head of high energy density physics at the Massachusetts Institute of Technology in a press release. “The 500 TW shot is an extraordinary accomplishment by the NIF Team, creating unprecedented conditions in the laboratory that hitherto only existed deep in stellar interiors,”