It’s the dream of spooks and teenagers alike: how to take photographs through opaque objects.
That’s always been impossible because light is so badly scattered when it travels through an opaque medium that it is impossible to reconstruct the original image. Or so we had thought.
Today, Sebastian Popoff and pals at the Langevin Institute in Paris show how it can be done with the aid of some mathematical trickery.
Send a laser beam through an opaque medium and all you’ll get on the other side is speckle: the beam has been mixed in a seemingly random as it bounces around and interferes inside the material.
But Popoff and co point out that however complex this process, multiple scattering is ultimately deterministic. No information is actually lost when the light is scattered. That means that it ought to be possible to extract the information, the only question is how.