A prototype system introduced to enable reading closed books

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A scanning system that can read closed books is presently being developed and tested. According to researchers, it is a prototype system that has been tested on a bundle of papers, each with a single letter printed on it. The system was able to precisely identify the letters on the first 9 sheets.


According to Barmark Heshmat, a scientist at the MIT Media Lab, “A lot of interest has been showed by the Metropolitan Museum in New York in this study as they intended to know the readings in ancient books that they do not even wish to touch.” He added that the system could be also useful to analyse the presence of materials organized in sleek layers, like coatings on pharmaceuticals and machine parts.

The algorithms developed by the researchers from MIT confirms that images acquired from separate sheets in a bunch of papers and the Georgia Tech scientists introduced the algorithm that analyses the often incomplete and distorted images as unique letters. “It is a little bit scary,” says Heshmat about the letter interpretation system. “Numerous websites has such letter certifications known as captchas to ensure that you are not a robot and this algorithm can provide you a lot of them.”

The system utilizes terahertz radiation, the group of electromagnetic radiation between infrared light and microwaves that has numerous advantages over other sorts of waves that can enter surfaces, like sound waves or X-rays. Terahertz radiation has been extensively tested for use in security screening as distinct chemicals absorb varying frequencies of terahertz radiation to distinct degrees, producing a varying frequency signature for each. But the same profile, terahertz frequency profiles can distinguish between blank paper and ink, in a way that X-rays cannot.

Terahertz radiation can be produced in such forms of short bursts that the distance it has moved can be gauged from the difference between its time of emission and the duration at which it reflected radiation returning to a sensor. That offers it much better depth resolution than ultrasound.

The device exploits the truth that captured between the pages of a book are small air pockets of just about 20 micrometres deep. The difference in the refractive index, which is the extent to which they refract light between paper and air, implies that the boundary between the two will reflect terahertz radiation reverse to a detector.

In the setup of researchers, a basic terahertz camera produced ultra-small bursts of radiation and the inbuilt sensor of camera identifies their reflections. From the time of arrival of reflections, the researchers of MIT algorithm can gauge the distance to the separate pages of the book.

While maximum of these radiations is either reflected or absorbed by the book, few of them bounced back around between pages, hence returning to the sensors, generating a spurious signal. The electrical of sensors also generated a background hum. Presently, the algorithm can precisely reduce the distance to the book from the camera, but the energy of the diffracted signal is extremely low due to which the differences between frequency signatures are infested by noise.