Read a book without opening it!
Q. A group of researchers have discovered a method to read a book without opening it. What type of radiation does this invention use?- Published on 13 Sep 16a. Terahertz radiation
b. Type of Electromagnetic radiation
c. Both a and b
d. Microwaves radiation
ANSWER: Both a and b
Researchers have described a prototype of the system which they tested on a stack of papers, one with each letter printed on it
- The system was able to identify letters on the top 9 sheets
- It was done with the help of terahertz radiation which is a band of electromagnetic radiation between microwaves and infrared light
- New system developed by researchers from MIT and Georgia Tech uses a standard terahertz camera to emit ultra short bursts of radiation and then measure how long it takes for the radiation to be reflected back
- Algorithm then gauges the distance to each of the individual pages of the book
- Terahertz radiation can be emitted in such short bursts that the distance it has travelled can be gauged from the difference between emission time and time at which reflected radiation returns to sensor
- This gives better depth resolution than ultrasound
- System cashes in on the fact that tiny air pockets about 20 micrometers deep are trapped between the pages of the book
- Difference in refractive index and degree to which they bend light between the air and the paper means that the boundary between the two will reflect terahertz radiation back to the detector
- Terahertz radiation can differentiate between ink and blank paper in manner that X-ray or ultrasound does not, offering much better depth resolution
- Terahertz radiation has been widely researched for use in security screening because different chemicals absorb different frequencies of terahertz radiation to different degrees yielding distinctive frequency signature for each.
