The computer generated holograms are holograms which give the appearance of binary representation of interferogram. Such holograms are produced with the help of computer and hence the name. Computers are used to scan, design, enhance and create images and patterns for developing 2D and 2D/3D holograms. These images, often cannot exist in the real world. This is a powerful technology suitable for a wide range of display types which includes 2D, auto stereoscopic, stereoscopic, volumetric, and true 3D imaging. Although computer based holograms are currently expensive for many applications, they will become a viable alternative in the near future.

How is a computer generated hologram created?

To make a computer generated hologram (CGH), the image of the object is first taken. The background of the image is then removed. Whitespace is added around the object which helps in obtaining higher transmission. There are three basic elements in holography. These are the light source, the image and the hologram. It is to be noted that if any two of these are known or predetermined, then the third one can be computed. For example, if we have two elements, say a parallel beam of light of certain wavelength and a "double-slit" system or a simple "hologram", the third element, that is diffraction pattern can easily be calculated. Similarly, if we know the diffraction pattern and the details of the double-slit system, the wavelength of the light can be calculated. This is the basic idea behind the computer generated hologram-we can dream up any pattern we want to view. In other words, once we decide what wavelength we want to use for observation, we can design the hologram by a computer. This computer generated hologram is growing rapidly.

Uses of Computer Generated Hologram

• CGH is used in the making of holographic optical elements (HOE) for various purposes like scanning, focusing & splitting.
• CGH is used for controlling laser light in many optical devices like a common CD player.
• Computer generated holograms are usually light weight .
• CGHs can create wavefronts of arbitrary complexity.

Applications of Computer Generated Hologram

Computer generated holograms are attractive and used in variety of applications to provide three dimensional views of an object. Some of the applications are as follows:

• Product packaging
• Packaging films
• Gift boxes
• Packaging foils
• Cartons
• Promotional labels and stickers
• Attractive for applications like optical data processing and optical testing.