The very first holograms were “transmission holograms”, which were viewed by shining laser light through them. A later refinement, the “rainbow transmission” hologram allowed viewing by white light and is commonly seen today on credit cards as a security feature and on product packaging. These versions of the rainbow transmission holograms are formed as surface relief patterns in a plastic film, and they incorporate a reflective aluminum coating which provides the light from “behind” to reconstruct their imagery
The very first holograms were “transmission holograms”, which were viewed by shining laser light through them. A later refinement, the “rainbow transmission” hologram allowed viewing by white light and is commonly seen today on credit cards as a security feature and on product packaging. These versions of the rainbow transmission holograms are formed as surface relief patterns in a plastic film, and they incorporate a reflective aluminum coating which provides the light from “behind” to reconstruct their imagery
