New technology that can read pages of a closed book
By: Team Ifairer | Posted: 12-09-2016
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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, such as X-rays or sound waves.
Terahertz frequency profiles can distinguish between ink and blank paper, in a way that X-rays can not, and 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 micrometres deep.