BBC Focus Magazine

[Shadowwolf]

The ability to see through walls is no longer the stuff of science fiction, thanks to new radar technology developed at MIT's Lincoln Laboratory.

Much as humans and other animals see via waves of visible light that bounce off objects and then strike our eyes' retinas, radar "sees" by sending out radio waves that bounce off targets and return to the radar's receivers. But just as light can't pass through solid objects in quantities large enough for the eye to detect, it's hard to build radar that can penetrate walls well enough to show what's happening behind. Now, Lincoln Lab researchers have built a system that can see through walls from some distance away, giving an instantaneous picture of the activity on the other side.

http://www.sciencedaily.com/releases/2011/10/111018102703.htm

[MikeG]

Sounds like something out of the movie 'Eraser'. All that's missing is the rail gun which fires projectiles through walls.

[Healerman]

I'm interested to see the day when the equivalent to the eye and the camera is developed for radio frequencies, seeing the ambient radio environment without transmitting an initial pulse.

I believe that something of this nature, albeit on a small scale, was achieved in the conflict in Bosnia, when cell-phone signals were used to "see" stealth aircraft, which are designed not to reflect signals back towards the source, but are perfectly visible with indirect "illumination".

In priciple, as with this development from MIT, you should get an image rather like an X-ray, seing the object, within it and beyond it, in essence, just as we see both the pane of glass and the view out of the window.

[M Paul Lloyd]

A passive radar system you mean Mr.H?

An interesting idea but you would have to be able to differentiate between the object you want to see and anything in its way or indeed behind it, which would be rather complicated, at least at close range.

In terms of an exotic radar, that could be used to illuminate a 'target' , along the lines of those used in military applications to resolve land contours, its down to microwave's being bounced off things and of course microwave's are part of the electromagnetic spectrum and indeed it has been tried but unfortunatley microwaves of sufficient frequency to resolve much detail tend to have a rather limited range and an unfortunate tendancy to 'excite' water molecules in anything they pass through. It works quite well on ground penetrating radar as used by forensic and archeological institutions but making solid objects transparent might require a different approach?

Its still an interesting idea though.