Identification medium and identification method therefor
An identification medium is provided in which latent image having plural colors can be observed even when the identification medium is spaced away from a polarization filter. A cholesteric liquid crystal layer is provided as a specific polarization light reflection layer which reflects light having a specific polarized condition. An optical anisotropic layer having an optical anisotropy is provided at an upper position overlapping with the specific polarization light reflection layer. An image A fanned by an area having an optical anisotropy different from that of surroundings is formed at the optical anisotropic layer. When the identification medium is directly viewed, the influence of the optical anisotropy cannot be seen. When the identification medium is observed via a circular polarization filter, the image can be seen to have a specific color by the influence of the optical anisotropy.
1. An identification medium comprising:
a reflection layer formed by laminating:
a metal reflection layer,
a linear polarization layer that selectively transmits linearly polarized light and is arranged at an observation surface side of the metal reflection layer, and a quarter wavelength plate arranged at an observation surface side of the linear polarization layer; and
an optical anisotropic layer which is disposed at an observation surface side of the reflection layer and at a position overlapping with the reflection layer, the optical anisotropic layer having an optical anisotropy in a plane,
wherein a first image formed by an area having optical anisotropy different from that of another area is provided at the optical anisotropic layer.
2. The identification medium according to claim 1 , wherein the reflection layer has a hologram processed portion.
3. The identification medium according to claim 1 , wherein the metal reflection layer is bonded to the linear polarization layer via a transfer bonding layer.
4. The identification medium according to claim 1 , wherein:
the optical anisotropic layer comprises a first region and a second region, which have different optical anisotropic characteristics from each other;
a difference of refractive indexes of perpendicular directions in the first region and a difference in the refractive indexes of perpendicular directions in the second region are different from each other; and
the first region and the second region are configured to be observed through a linear polarization filter or a circularly polarized light filter as having different colors.