Researchers from Massachusetts Institute of Technology (MIT) in the US have already conducted a series of experiments by testing a prototype of the system on a stack of papers, each with one letter printed on it. They found that the system can correctly identify letters on the top nine sheets.
This system can be used to study any materials organized in thin layers. It can analyze coatings on pharmaceuticals or machine parts.
Organizations have started showing interest in this new system. “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,” said Barmak Heshmat, a research scientist at MIT.
The researchers have also developed algorithms that acquire images from individual sheets in stacks of paper, and interpret the often distorted or incomplete images as individual letters.
In fact, this algorithm can work even with many websites that have letter certifications (captchas) to make sure the user is not a robot. The algorithm can get through a lot of them.
You must be wondering how the entire system works. The system uses terahertz radiation that has many advantages over other types of waves that can penetrate surfaces. This radiation is the band of electromagnetic radiation between microwaves and infrared light.
This radiation is no doubt better than X-rays or sound waves. In fact, terahertz frequency profiles can differentiate between ink and blank paper which X-rays cannot. Moreover, this radiation has much better depth resolution than ultrasound.
The system exploits the fact that between the pages of a book tiny air pockets are trapped about 20 micro metres deep.
The difference in refractive index between the air and the paper means that the boundary between the two will reflect terahertz radiation back to a detector. This difference is the degree to which they bend light.
In the new system, a standard terahertz camera emits ultra short bursts of radiation, and the camera’s built-in sensor detects their reflections.
This new technique might help archaeologists, doctors, research scholars to look into books without even touching them. In fact, this technique can be very useful for those who want to look into some antique books without even touching them.