Array of cat's eye retro-reflectors with modulability for an optical identification system

In this paper, we present an array of cat's eye retro-reflectors with modulability for an optical identification (ID) system. The modulability is obtained through the use of a smart film, a polymer dispersed liquid crystal device (PDLC). Switching of the image pattern of retro-reflected light is demonstrated. Such a dynamic image can function as the "key" so that a high-security, high-privacy identification system can be constructed.