Cellphone theft would be pointless if the devices cut out as soon as they fell into the wrong hands. But adding a fingerprint recognition system and another window to press your finger on makes phones too bulky. Now US company Identix says an all-purpose phone screen made from glass with a very low refractive index will do the trick (WO 03/012729).
The owner of the phone places a fingertip on the window, and red light from an LED underneath reflects from the bright ridges of the finger. Through total internal reflection, the fingerprint pattern “bounces” out through the glass…
