IDENTIFICATION MEDIUM, IDENTIFICATION METHOD OF IDENTIFICATION MEDIUM AND OPTICAL DEVICE FOR OBSERVING IDENTIFICATION MEDIUM

摘要

PROBLEM TO BE SOLVED: To provide an identification medium whose image being observed looks changing in visually recognized size, looks three-dimensionally standing out or sinking and, at the same time, looks changing in colors. SOLUTION: The identification medium includes: a nematic liquid crystal layer 103 which is constituted at least of one layer of nematic liquid crystal wherein the product of birefringence and helical pitch of a liquid crystal molecule with respect to visible light viewed from the observing side is at least more than 3.5 times larger than the wavelength of the visual light and selective reflection by Bragg reflection does not occur; and a reflection pattern 104 which overlaps the nematic liquid crystal layer 103 and constitutes a light reflection layer whereon a light reflection pattern is formed so that a pattern appears repeatedly at predetermined pitches. COPYRIGHT: (C)2011,JPO&INPIT