New 'air lasers' could help detect bombs, pollution and more

We just learned that plants are getting in on the bomb detection game, and now lasers are looking to join the club. Not just regular ol' lasers, either — "air lasers."

We already use lasers to "sense" all kinds of stuff, the most common being range. But what you can detect with a laser can be hampered by relying on the information that bounces back, as it can be distorted or scattered.

A new approach taken by engineers at Princeton University involves a beam that is generated by excited oxygen atoms, and can gather information from virtually anywhere: "We are able to send a laser pulse out and get another pulse back from the air itself," Richard Miles, a group leader on the research and professor at Princeton, said. "The returning beam interacts with the molecules in the air and carries their finger prints."

The air laser wouldn't spot bombs by shining a beam right at them. Instead, it'd be used to sample the air around where a device is thought to be — making the laser useful in other fields as well, such as testing for pollution and greenhouse gas.

Here's the breakdown:

The new laser sensing method uses an ultraviolet laser pulse that is focused on a tiny patch of air, similar to the way a magnifying glass focuses sunlight into a hot spot. Within this hot spot — a cylinder-shaped region just 1 millimeter long — oxygen atoms become "excited" as their electrons get pumped up to high energy levels. When the pulse ends, the electrons fall back down and emit infrared light. Some of this light travels along the length of the excited cylinder region and, as it does so, it stimulates more electrons to fall, amplifying and organizing the light into a coherent laser beam aimed right back at the original laser.

While the technology looks like it's pretty much ready to go, there's no word on how the researchers tend to package it to make use of it, or when it'll go into action.

Via EurekAlert!

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