Which Book Carries Its Own Light?

How many times have you been told not to read in bed and how often have you been ticked off for reading in poor light? Probably quite a few times if you are an avid book-worm. Now you can cast away your small flashlights and get rid of your reading lamp, for there are specially designed books that create their own light!

The glowing book

Professor Janos Hajto of Napier University, Edinburgh, has created a book with special plastic sheets that glow in the dark. He calls his invention ‘Freelight’.

Freelight uses a concept similar to “glow-in-the-dark” toys, but is much more powerful. The pages of the book have been created after adding a light-emitting dye to thin plastic sheets. The dye makes the pages glow in dark and enables you to read this book even when the lights are off.

A glowing dye

So how does this dye glow? Certain materials can absorb energy and emit it in the form of light. If the interval between absorption and emission is short (within a second or two, as in tubelights) this process is called fluorescence; if the interval is slightly longer, the process is called phosphorescence. Freelight uses phosphorescence to create its own light

In a Freelight, the dye absorbs light from the environment and re-emits it after a while.

Unlike solar panels, which rely on direct sunshine, Freelight absorbs enough energy even on a dull day. Professor Hajto points out that since Freelight does not use electricity, it could be an economical way not just to light up books but to illuminate entire streets, computer screens and hoardings!

For once, no one can complain that the light is not bright enough for reading!