It’s not your traditional camera and it obviously does not rely on the visible spectrum of light radiation to produce an image.
Instead, this computational imaging system uses terahertz radiation, the band of electromagnetic radiation between microwaves and infrared light, to read through closed books.
Like X-rays and sound waves, terahertz radiation can also penetrate surfaces; more importantly, unlike X-rays and sound waves, terahertz frequency profiles can also distinguish between ink and blank paper, thus allowing it to “read” the words printed on paper.
This prototype is a joint development between MIT and Georgia Tech: the MIT researchers developed the algorithms that acquire images from each individual sheet in a stack of paper, and the Georgia Tech researchers developed the algorithm that interprets the often distorted or incomplete images as individual letters.
Although the algorithms can correctly read the top 20 pages in a stack of paper, only the first nine pages yield readable letters; the other eleven pages reflect so little energy signal that they are swamped by “noise.”
In their tests, a stack of paper were used, with one letter printed on each sheet of paper. The system was able to correctly identify the letters of the top nine sheets of paper in the stack.
One practical application of this imaging system would be to allow museums to read antique documents with pages which are too fragile to handle.
Read more at: MIT News
Book mentioned in the video: “Physics of the Impossible: A Scientific Exploration into the World of Phasers, Force Fields, Teleportation, and Time Travel” by theoretical physicist Michio Kaku.