Researchers at MIT and Georgia Tech can now read nine pages into a closed book, a major feat for terahertz technology that could impact the study of ancient documents and even have implications for cybersecurity.

Ten years ago, MIT researchers found that you could use terahertz radiation–which falls between microwaves and infrared light on the electromagnetic spectrum–to read a letter through a closed envelope.

The new research, published in the journal Nature Communications, describes a prototype for an imaging system that uses a terahertz pulse that can reflect the tiny air gaps between the pages of a book. MIT-created algorithms receive the images of the words from the closed books, which appear to be distorted or incomplete, due to words from pages above and below showing through, but the Georgia Tech team developed an algorithm that interprets these images, according to MIT News.

“The Metropolitan Museum in New York showed a lot of interest in this, because they want to, for example, look into some antique books that they don’t even want to touch,” Barmak Heshmat, a research scientist at the MIT Media Lab and co-author of the study, told MIT News. The system could potentially analyze any materials organized in thin layers, including pharmaceuticals, he added.

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One unexpected side effect of the Georgia Tech algorithm, that could have far-reaching implications: It can interpret and solve online certifications, such as captchas, which are commonly used to keep malicious bots at bay.

Terahertz radiation is used in research around security screening–unlike X-rays, it does not damage tissues or DNA. Also, “terahertz frequency profiles can distinguish between ink and blank paper, in a way that X-rays can’t,” according to MIT News.

The MIT algorithms can identify the distance from the camera to the top 20 pages of a book. However, after nine pages, the signal is too low to decipher the letters.

But since terahertz imaging is relatively new, and more and more researchers could eventually be using it, it’s likely that the technology will improve over time, Heshmat said in a video.

“So much work has gone into terahertz technology to get the sources and detectors working, with big promises for imaging new and exciting things,” Laura Waller, associate professor of electrical engineering and computer science at the University of California at Berkeley, told MIT News. “This work is one of the first to use these new tools along with advances in computational imaging to get at pictures of things we could never see with optical technologies. Now we can judge a book through its cover!”

The 3 big takeaways for TechRepublic readers

  1. Researchers from MIT and Georgia Tech created a prototype system that can read nine pages into a closed book using terahertz technology, which could have implications for studying ancient or fragile texts.
  2. An MIT algorithm receives images of words from the closed books, while a Georgia Tech algorithm deciphers them. The latter can also decipher online captcha codes.
  3. As the terahertz technology continues to improve, it’s likely that researchers will be able to read deeper into closed books in the near future.