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Pulse of infrared light created by air laser  (Source: Image courtesy Arthur Dogariu, Princeton University)
Laser sensor is 1,000 times more powerful than LIDAR

The U.S. military is spending significantly on research into the use of lasers as weapons and sensory devices. A research program funded by the Office of Naval Research at Princeton University has announced a significant breakthrough in the use of lasers as sensors.

The research team has developed a new laser that may be able to detect bombs and pollutants from a long distance. The breakthrough is called the Air Laser. Richard Miles, professor of mechanical and aerospace engineering at Princeton said, "We are able to send a laser pulse out and get another pulse back from the air itself. The returning beam interacts with the molecules in the air and carries their finger prints."

The technique uses a laser beam shot at a target and the beam excites a cylinder of air as it passes that is only a millimeter wide. The region that the beam passes through is a hot spot that creates excited oxygen atoms that have electrons pumped up to high energy levels. As the laser pulse ends, the electrons fall back down and emit infrared light. That light passes back through the cylinder that the original laser beam created and transmits back to the original point of origination for the laser beam. A sensor at the originating spot would be used to receive the beam that comes back to the source and determine what contaminants it encountered on the return trip to the sensor.

Miles said, "In general, when you want to determine if there are contaminants in the air you need to collect a sample of that air and test it. But with remote sensing you don't need to do that. If there's a bomb buried on the road ahead of you, you'd like to detect it by sampling the surrounding air, much like bomb-sniffing dogs can do, except from far away. That way you're out of the blast zone if it explodes. It's the same thing with hazardous gases – you don't want to be there yourself. Greenhouse gases and pollutants are up in the atmosphere, so sampling is difficult."

A technique that is similar to what the Princeton team has developed already in use today is LIDAR. LIDAR is used to measure density of clouds and pollutants in the air. The problem is that LIDAR isn’t sensitive enough to detect trace amounts with accuracy. The Princeton method developed is about a thousand times more powerful than LIDAR.

The much stronger beam will allow the scientists to measure the trace elements encountered on the way back. Those trace elements could be atmospheric pollutants or vapors released by explosives.

Miles said, "We'd like to be able to detect contaminants that are below a few parts per billion of the air molecules. That's an incredibly small number of molecules to find among the huge number of benign air molecules."

The Navy's laser platform for destroying missiles in flight was announced to be 9-months ahead of schedule last week.



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This is pretty cool...
By MrBlastman on 1/31/2011 12:13:19 PM , Rating: 3
What I really want to know is what is the wattage and concentation of the beam in regards to potential to damage eyesight. I imagine it is very focused for this to work properly at range--but at what range? Is this limited to say a scanning booth that you walk through (that would be okay and much better than say those full body scanners which have lead to my boycott of flying--well, that and the enhanced pat down)?

I'd say this potentially could be far more harmless than even an x-ray scanner. However, how much motion from the target is permitted? I realize that "smells" diffuse very quickly, but sudden motion by the subject could effect the diffusion and how much of it wisps away from the scan area.

I'm sure it isn't foolproof, though, as the bomb carriers would figure out ways to seal or hide the smell--so multiple layers of detection will need to be used so, more data and work is needed. The goal of all the work though, is to avoid the full body scans.




RE: This is pretty cool...
By radicledog on 1/31/2011 3:17:24 PM , Rating: 3
Great, now the streets are going to be full of angry out of work bomb sniffing dogs. Just what our economy needs!


RE: This is pretty cool...
By kontorotsui on 1/31/2011 4:26:22 PM , Rating: 1
quote:
Great, now the streets are going to be full of angry out of work bomb sniffing dogs. Just what our economy needs!


Don't worry, they will soon switch to green economy jobs and start living on State subsidies.


By Brigga on 1/31/2011 8:09:44 PM , Rating: 2
Can't wait for this to come to the general public. A new fart sniffing laser. Never be caught in the lunch room again!




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