Using technology akin to X-ray vision, scientists can read closed books, identifying
letters printed on stacks of paper up to nine sheets thick.
This finding could lead to office machines that can scan reams of paper at once, or help researchers scan ancient books that are too fragile to open. The researchers also said it could perhaps help spies read mail without opening envelopes.
The prototype device uses terahertz radiation, the band of electromagnetic radiation between microwaves and infrared light. Previous research has found that terahertz rays, or T-rays, possess a number of advantages over X-rays, ultrasound waves and other kinds of radiation that can penetrate surfaces. For instance, terahertz rays can distinguish between ink and blank paper in a way that X-rays cannot. They can also scan across depths to yield higher-resolution images than ultrasound can accomplish, according to the researchers. [6 Incredible Spy Technologies That Are Real] https://www.livescience.com/56054-new-tech-could-read-closed-books.html
