'Air laser' tech could sniff bombs, probe atmos from afar

Military- and security-funded boffins have been trying to develop better bomb-detecting technology for many years now. Most of what they come up with has obvious defects: typically sensors either don't actually detect explosives but rather associated substances or shapes (metal detectors, X-ray systems) or they need to be very …

[Anonymous Coward]

Tupperware air tight containers now to be restricted from sale

Sounds like a useful research tool.

However, ignoring the crack about air tight containers, how would you be able to tell the difference between your bombs, bullets, etc. and their bombs, bullets, etc., in a light wind condition, with rain, or the other stuff that occurs outside of a lab?

i.e. How does it work if your people have just expended a few thousand round, grenages, etc., and now wish to proceed down the road in front of you?

The other concern is how do you make precision optics squadie proof?

[John Sager]

Not near my eyes!

I wouldn't like to be close to the air volume illuminated by the UV laser. The power density must be phenomenal in that volume to get the air to lase.

[Martin Gregorie]

My thought exactly

Anywhere beyond the lasing point and on the beam line wouldn't be too pleasant either. Apart from a very nasty case of sunburn, what about damage to eyesight?

[Anonymous Coward]

These people dont watch the right SF shows

I would have rated firing laser(pistol?)s at suspected explosives about as valid a method as trying to locate missing vulnerable persons at night by shooting randomly into the dark and listening for the screams.

[Simon Neill]

Range?

How would you range the return signal? Say you focus the beam to scan from 30 feet away, how do you know the bomb is 30 feet away rather than say...3 inches? It makes a big difference if said bomb is triggered by a pressure sensor or trip wire...

I'm assuming this is some sort of spectrophotometry dealio?

[Wind Farmer]

How is this meant to be deployed?

If it is necessary to energise "a cylinder of air just a millimetre long, situated at the place to be scanned, and turns it into a gas laser aimed back at the scanner", how do you place the cylinder beside the point to be scanned? And move it to the next point? And are there issues with ensuring that it is aligned in a manner that aims it "back at the scanner"?

[crowley]

Magic

I understood it as meaning that the UV laser energises the cylinder of air it's focused upon in such a way that the energy is then emitted as an infrared laser pulse. That is, they actually create a laser emitter from the air itself!

This IR pulse is then distorted by the gas in its return path, allowing the bomb substances to be detected - somewhat similar to spectrum analysis I guess...

I'd be intrigued to know if the pulse is -only- emitted along the return path to the original UV laser pulse, or if it is omnidirectional. If the latter, perhaps it could be detected so as to trigger some other... effect. I guess that would also allow unguided laser communications around corners, though presumably only with a very precisely targeted receiver, and at a quite appalling data rate.

[Chimp]

Back in the day...

We'd just get the new boy to chuck a brick at suspicious objects. If he was really new, there'd be a flashbang in it. Then there'd be two bricks, one on the ground and one in the lad's trousers. How we laughed... 'course, nowadays, they come down on that sort of thing like... Well, a ton of bricks.

[Graham Marsden]

And how easy is it to spoof?

As soon as I read this, I thought "ok, what if someone plants a few cannisters of petrol/ gas/ diesel etc with pinholes to allow them to leak slowly?"

Every detection would have to be checked out and operations would be slowed to a crawl.

[Mermaid Dick]

Jamming

The obvious countermeasure against such a gadget - if it ever makes it out of the lab - would be to jam it with the real thing. If there is a detectable signal from a buried bomb, it would be easy to make a thin dilution of the same explosive in some suitable solvent and then drip it slowly from a car driving the same route.

This would overload the bomb detector with substance carrying the same signature as the hidden bomb. Detecting a low signal against a high and fluctuating background would be hard indeed. Then give all roads the same marking, whether there are bombs there or not. So there will be false alarms all the time.

[brainwrong]

Laser?

Lasers use reflecting surfaces at each end of the cavity, does the magic UV laser create these too at each end of the little cylinder of energised air?

I imagine it doesn't, and just produces a coherent light source which is fairly directional along the axis of the cylinder of air.

As others mention, it doesn't sound very safe. Does the little cylinder of air only emit IR, or is there any visible light too? It's bound to make a sound.

It also sounds like they haven't actually tried any sort of substance detecting stuff with it yet.

Best go with the laser warning symbol

[Alan Brown]

Or detect the bomb factories from a distance...

If this really works, then a village can be checked out pretty quickly and only the houses which actually smell of explosives need someone going near them.

Of course in places like afghanistan where everyone and his pack mule carries a gun there are likely to be too many false positives to be worthwhile.

[Starlite Lemming]

Holograms, anyone?

I love this idea!

I wonder if this could be developed into Star Wars-like holograms...