MIT researchers discovered how to read through a stack of papers using a terahertz camera and computational imaging. Their current results are promising and could have huge implications for historians, librarians, and maybe even secret agents. Barmak Heshmat, research scientist at the MIT Media Lab, reads through a closed book. (via Barmak Heshmat)
MIT researchers have created a whole new technology. Well, at least they've created a whole new technology out of existing technologies - which is still pretty impressive. Researchers of the MIT Media Lab, including Barmak Heshmat, have discovered a way to read through closed books using a terahertz imaging camera and an algorithm developed by Georgia Tech.
A terahertz camera uses terahertz radiation, which is a form of electromagnetic radiation within the range of microwaves and infrared light. Terahertz radiation is special in that different substances absorb terahertz radiation at varying frequencies which can create a type of signature. For instance, TSA wanted to use terahertz radiation to detect potentially dangerous chemicals: the radiation would be absorbed differently by water vs. alcohol, allowing travelers more privacy and less hassle.
This same principal came in handy in determining ink on a page from blank paper. The researchers used signatures for various types of ink to determine what/if writing was on the page.
Further, terahertz radiation also allowed the researchers to distinguish between different pages. Using timing, the researchers we’re able to determine the tiny spaces between pages. In between the sheets of paper are air pockets about 20 micrometers deep - they were able to distinguish what layer they were looking at by measuring the time it took for the radiation to reflect back to the sensor in the camera and by the types of frequencies reflected back.
The final piece in turning this data into something useful and meaningful is a complex algorithm that determines what letters are on the page and completes missing letters. Because of the nature of the technology, the letters from both sides of the sheet can be read; so the ink data from the ink printed on the back side of the paper can be seen mirrored behind the letters on the front page. This phenomenon causes some strange shapes and seemingly incomplete letter structures. Hence, Georgia Tech's algorithm makes sense of the terahertz imaging to create a clearer "picture” of each individual page and its text.
This technological pairing has allowed them to correctly look through the top 20 pages in a stack of papers, however, they can currently only effectively read the first nine pages because the amount of noise is too great to make out any letters. An incredible amount of noise is caused by radiation bouncing between pages and by amounts of radiation frequencies lost or absorbed.
However, this is certainly a promising start and the MIT researchers are certain that advances in technology will allow them to delve further to eventually read an entire book without opening it. Historians and librarians are salivating over the prospects of being able to read ancient books that must be kept closed and never touched. Perhaps this technology will be implemented in the next 5 to 10 years and we can learn more about ancient history through the secrets such books hold.
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