Ambient Radiation Sensors
Here’s a piece of interesting research out of Ohio State: it’s a passive sensor that could be cheaper, better, and less intrusive than technologies like backscatter X-rays:
“Unlike X-ray machines or radar instruments, the sensor doesn’t have to generate a signal to detect objects it spots them based on how brightly they reflect the natural radiation that is all around us every day.”
“It’s basically just a really bad tunnel diode,” he explained. “I thought, heck, we can make a bad diode! We made lots of them back when we were figuring out how to make good ones.”
First millimeter-wave detection systems, and now this. There’s some interesting research in remote sensing going on, and there are sure to be some cool security applications.
DarkFire • August 24, 2005 8:58 AM
Personally I’m highly sceptical about the concept of using this sort of device to scan people & luggage.
Using a hugely broad spectrum of ambient radiation has a whole hoast of technical difficulties that in my oppinion are incredibly challenging to overcome:
1) Different locations have wildly differing levels of ambient radiation of all forms.
2) Having a sensor not physically in contact with the target would mean that the signal one is looking for is submerged in the very sea of ambient radiation that is being used as an illumination source. This would present tremendous signal-to-noise ratio problems.
3) Most ambient radiation will be in RF bands. I seriously question the assertion that this is good enough to provide an imaging capability. Traditionally it has been very difficult to image anything below the wavelength of the radiation being used. Advanced signal processing might make this feasable down to maybe quarter-wavelength but this stil presents a problem.
I can see this being very useful for pilots of airliners being able to see a runway because a runway is a huge lump. A small knife in someones pocket presents a whole different problem – you need imaging capability that is 2-3 orders of magnitude more detailed.
I would imagine that signal analysis could maybe porovide a working system, but we would be talking about signal processing about a generation better than what’s in a modern submarine. Expensive.
To sumn up, I can’t see this being a viable technology with regards to imaging small objects without an active source of illumination.