What is a Hologram? - a hologram is the art of displaying a three-dimensional picture of an object on a two-dimensional carrier. It was invented in 1947 by Dennis Gabor who was awarded a Nobel Prize in physics in 1971. Holography allows a photograph to be displayed as a three-dimensional object. It takes two steps to create a hologram:
(1) - The first step is the creation of the hologram through light reflection.It was not possible to create a hologram until the invention of the Laser (Light Amplification by Stimulated Emission of Radiation). The LASER provides the single beam light sources which enable us to create the hologram.
How is the Hologram Created? - First we need a drawing, picture or a carved model. For example: the Rega issue used three components to form the hologram image. This is why it is referred to as a 2D/3D hologram. The 2D hologram components are:
(1) Ambulance plane (Hawker 800 B)
The above three 2D components were layered to create the 3 dimension of the hologram. The first two pictures from the top down above show the plane, Rotor and Mountains. The picture on the bottom above shows all three images layered together to form the three dimension. An example diagram and explanation of the layered process to create the hologram film is as follows:
The three picture images were then scanned by laser beam and the reflection inference beam was registered on a photosynthetic foil. The Diagram above shows a laser beam being divided into 2 halfbeams (object beam & reference beam) by using a special mirror called a beam splitter. During the process, each half beam is expanded with a lens and the object beam illuminates the object. The object beam is then reflected, and both half-beams meet again in the holographic master (film) where they create an interference image. This interference image holds the 3-dimensional information of the object (position, size and depth of the object). At this point, the hologram is only a latent image on the film. The permanent hologram image (the hologram master) is created by photochemical development. In the case of the Rega issue, three latent images were generated and recombined in order to create the hologram master. The foil surface consists of lines and notches which are as fine as the laser beam used. The surface relief structure of the Rega issue was created by use of the interferential microlithography method.
Finally a micro thin aluminum layer and an electron beam curing process is done to make the hologram permanent. The hologram foil is ready to be applied to the stamp. In the case of the Rega commemorative issue. Five colors are used in an offset printing machine. The hologram foil is in a roll which contains thousands of individual holograms. It is applied on the printed sheets by hot foil embossing. A process that uses heat and pressure using a polished metal plate. The heated metal plate on the counter print cylinder glues the so-called "hot melt layer" of the hologram onto the printed stamp. The process is finally done.
Cancellation - holograms do accept ink of cancellors used by post offices and philatelic outlets. However, a special ink is needed, because the ink being used now by most post offices does not dry very well on hologram foil stamps. It can easily be smudged or smeared at any time.The technical data and pictures for this insight were taken from "The collector's Magazine" issued by the Swiss Postal Service on 1/2002.