The first step in the embossing process is to make a stamper by
electrodeposition of nickel on the relief image recorded on the photoresist or
photothermoplastic. When the nickel layer is thick enough, it is separated from the master
hologram and mounted on a metal backing plate. The material used to make embossed copies
consists of a polyester base film, a resin separation layer and a thermoplastic film
constituting the holographic layer.
The embossing process can be carried out with a simple heated press. The
bottom layer of the duplicating film (the thermoplastic layer) is heated above its softening
point and pressed against the stamper so that it takes up its shape. This shape is retained
when the film is cooled and removed from the press. In order to permit the viewing of
embossed holograms in reflection, an additional reflecting layer of aluminum is usually
added on the hologram recording layer.