Method for using a deep image hologram as a security device and a deep image hologram

摘要

A holographic optical element (HOE) that is comprised of a deep image hologram and a method for using this HOE as a security device are described. The deep image hologram is viewable 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 of the deep image hologram. The deep image hologram is not viewable (i.e., appears essentially unrecognizable to the human eye) with a diffuse lighting source, such as ordinary room lighting.