How to read a closed book

MIT researchers and their colleagues are reading closed books based on a new imaging system. The system could be used to assess any materials arranged in layers that are thin, including coatings on pharmaceuticals or machine parts.

The system uses terahertz radiation, the band of electromagnetic radiation between microwaves and infrared light, which has several advantages over other types of waves that can penetrate surfaces, including X-rays or sound waves. Because distinct compounds absorb different frequencies of terahertz radiation to different amounts, yielding a frequency touch that was distinctive for each Terahertz radiation has been extensively studied for use in security screening. By the same token, terahertz frequency profiles can distinguish between ink and blank paper, in a sense that X-rays can’t.

Read more at MIT’s news channel.