Security device using a hologram reconstructing a deep image

摘要

A holographic optical element (HOE) capable of reconstructing a deep holobject (i.e. object holographically reconstructed) and a method for using this HOE as a security device are described. The deep holobject is viewable when the HOE is illuminated with a collimated or at least partially collimated light source having a center wavelength in the visible region of the electromagnetic spectrum and a spectral bandwidth, wherein the spectral bandwidth of the collimated or at least partially collimated light source at least partially overlaps the spectral bandwidth wherein the holobject is restored. The deep holobject is not viewable (i.e., appears essentially unrecognizable to the human eye) when the HOE is illuminated with a diffuse lighting source, such as ordinary room lighting.