X-ray vision is possible for Superman, but in the real world, it’s a lot harder to do. However, a couple of guys at the Massachusetts Institute of Technology have found a way to duplicate –- sort of -– Superman’s amazing feats.
Two researchers at MIT’s Lincoln Lab, John Peabody and Gregory Charvat, think they have a way around that, and it involves a system of signal amplifiers and radio wavelengths. The results could lead to a new kind of radar that offers real X-ray vision to soldiers in urban combat zones.
To see through walls, you have to deal with the fact that solid objects absorb, scatter or reflect light and radio waves. This is why X-ray machines and radar work the way they do. When a doctor takes an X-ray image, the solid bone (and any metal you are carrying) shows up as bright white because other body parts, which are mostly water, allow X rays to pass through them, whereas bones and metal don’t. Radar works by picking up reflected radio waves from (mostly) metal objects. A radar operator can “see” a plane from miles away because of the radio waves bouncing off it.
If one uses an X-ray machine to take an image of an object behind a wall, the wall shows up very brightly. Only a small bit of the radiation penetrates the wall, and an even smaller bit reflects back to the detector.
Peabody and Charvat came up with the idea of amplifying the faint signal that does make it through, and subtracting out the signal produced by a concrete wall (above).
The first problem wasn’t that hard, as signal amplifiers are easy to make. Teasing out an image from the reflected radiation was the challenge. Longer wavelengths pass through solids more easily (this is one reason your radio works inside your house). But the longer the wavelength, the bigger your antenna has to be and the slower the data is transmitted.
The researchers chose the wavelength they did because it is small enough that the radar apparatus can be about eight feet long. Then they looked at how to filter the signal and see what is behind the wall. When a radio signal passes through a wall, hits something and bounces back, it’s wavelength changes. Using an analog crystal filter, they were able to build a receiver that will only pick up signals of the altered wavelength. That effectively deletes the wall from the image.
Right now their device shows people as blobs beyond the wall, but they hope to improve it. As it is, they're able to take video at about 11 frames per second.
There are some limitations: the way the device takes images is by subtracting certain signals and comparing it to a previous image, so anything that isn’t moving will not show up. That means a person would look like an inanimate object, provided they stay still.
But even in its raw state, it can still help first responders look through walls to see if anyone is in a building -– or aid soldiers in urban combat zones. It was the latter that Peabody and Charvat had in mind when they designed it. To that end they are working on improving the image quality to make the system more user-friendly.
Via MIT News
Images: David Waldorf/Getty Images and MIT Lincoln Lab