hologram display

[seminar class]

A hologram is a type of three-dimensional image that gives the appearance as a real object as the image has depth. The best way to think of a hologram is to visualize them as impressions on light waves. The patterns of light wave impressions are photographed or captured in the layer of emulsion. In other words, a hologram is an image or photograph of light wave interference. It is to be noted that not all 3D images are holograms and neither a hologram is required to be 3D. In technical terms, a hologram is the captured intensity and phase information which is produced by the interference or interconnection of two or more beams of light. People often consider a hologram as some type of a three-dimensional photograph. However, the only thing common between photography and holography is the use of a photographic film. The important difference is the way the image is produced in both the cases. A photographic image is produced by a camera lens and it is described almost accurately using a simple geometric or ray model for the behavior of light. On the other hand, the holographic image is formed depending on diffraction and interference, which are wave phenomena.
Holograms have some very interesting properties such as follows:
• Distributed information: The information in a hologram is always distributed. If it is cut into pieces, each piece contains enough information to reconstruct the entire scene.
• Image projection: Under certain cases, merely shining or lighting a laser through the hologram projects an image on to a screen.
• Viewing directly with a point source: A hologram reconstruction shows exactly the same light wavefronts to our eyes that we receive with the real object, using a point source of illumination. The hologram is not distinguished from the physical object.