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U.S. Air Force using airborne lasers as high-speed, wireless data links

By | October 28, 2009, 3:14 PM PDT

U.S. Air Force jets and drones could soon send high-quality video and audio of the battlefield wirelessly using high-bandwidth lasers.

The Air Force Office of Scientific Research says it has conducted experiments to transmit data optically, without interference, across long distances up to 22 miles.

That’s a big deal because transmission of information through turbulence distorts it, researcher David Hughes of the Air Force Research Laboratory said.

“[It's] just like the information coming from the light reflected off a distant, twinkling star to your eye. It’s fuzzy,” Hughes said in a statement. “You have to overcome that by using adaptive optics to rectify the distortion and get a better quality signal.”

Hughes and his team have conducted high data-rate experiments using an optical laser link, a tool which “exploits the quantum noise of light for higher security.”

That translates to easier military access to real-time intelligence data from manned and unmanned airborne platforms.

The Register (UK) writes of the security potential, too:

The idea is to use a laser beam through the air to carry information optically in the same way that sending light down fibre works. In the case of fibre, it’s possible to send information - for instance encryption keys - coded as individual photons, quanta of light. Any attempt to intercept such info would by definition involve changing it, meaning that any eavesdropping would surely be detected. Thus quantum methods might offer better security.

The Air Force is working with AOptix Technologies, a developer of ultra-high bandwidth laser communication, on the project.

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Andrew Nusca

About Andrew Nusca

Andrew Nusca is editor of SmartPlanet.

Andrew Nusca

Andrew Nusca

Editor

Andrew Nusca is editor of SmartPlanet and an associate editor for ZDNet. Previously, he worked at Money, Men's Vogue and Popular Mechanics magazines. He holds degrees from the Columbia University Graduate School of Journalism and New York University. He based in New York but resides in Philadelphia.

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Andrew Nusca

Andrew Nusca
Andrew Nusca does not hold any investments in the companies he covers.
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Security, not transmission clarity
Encryption key sending is all well and good. But the biggest security feature is that the beam is next to impossible to intercept in the first place.
Posted by Dr_Zinj
29th Oct 2009
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RE: U.S. Air Force using airborne lasers as high-speed, wireless data links
In about 1971, engineers at Case Western Reserve University (in
Cleveland Ohio), in cooperation with the Anesthesiology Dept.
of their Medical School) transmitted video and voice via a laser
link from a satellite hospital to/from the University Hospital. I
personally observed this system working (as it did work for
several months/years). There were problems from rain and
birds, but it did prove in principle that the technology did
work---40 years ago. There are still people at CWR who used
the system if you want more information.

Wesley T. Frazier MD
Atlanta/Bellingham WA
Posted by wesleyfrazier@...
29th Oct 2009
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RE: U.S. Air Force using airborne lasers as high-speed, wireless data links
Aiming is a serious issue. The problem is that laser beams, by nature, do not spread. A laser that has a beam width of 2mm leaving the laser, has a beam width of 2mm 35miles away. This makes it a serious problem for aiming. How do you aim a 2mm diameter dot when it's so far away, you can't see it?

I worked for a company which looked into this for terrestial communications. If you place the laser on a tower and a target on a tower 22miles away, both towers twist and sway. A twist of half a degree means you're way off target. A sway of one foot also means you miss your target. The mechanisms required for compensating for this kind of twist and sway are, some have said, intractable.

Placing a laser on a flying aircraft and trying to place a 2mm diameter dot onto a target 22miles away, is considerred intractable. Vibrations in the aircraft, and wworse, turbulence, cause the dot to move a lot.

Oddly enough, it's easier to hit a geosynchronous satelite from a laser sitting on the ground than it is to communicate between two towers. Neither the ground nor the setelite move much.

The solution to the movement problem is to shine the laser through a lens, thus causing the beam to spread. So instead of it being 2mm in diameter 22miles away, it's 20 yards or more in diameter. This makes it easier to hit the target. I assume this is what they are doing.

Quantum encryption requires the use of two entangled photons. For the message to be received and decoded, both photons need to be received. With an optical fibre, this isn't a problem. When you're using a laser with a spread lens, this is a problem. If the target is 3 feet in diameter, and the beam spread is 20 yards in diameter, a good number of the photons are going to end up not hitting the target. THis means that you have a good chance of getting only one of a pair of entangled photons and that gener5ally isn't good enough.

How they solve this problem, I very much look forward to reading about some time in the future.
Posted by mheartwood
29th Oct 2009
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