The word “holography” is invented from the Greek words “holos” means “whole” and “graphe” means “writing”.
The term "hologram" was also invented from the Greek words holos means "whole," and gramma, means "message."
A hologram is a recording of an object by the method of holography by using light waves.
Holograms are very interesting and remarkable subject which can not be explained but can be appreciated in visualization. These are apparently floating three dimensional image has taken a good space in all over the world in developing ad under developed countries. People are carrying one or two holograms every time with them. They can be in their credit or debit cards, CD or DVDs.
The production of holograms is very technical in nature. Holography works upon the physical properties of light that creates the magic. When light waves are reflected from an object they create different amplitudes, wavelength and phases which bring about interference with each other and thus affect the visual perception of the object.
Holographs are different from photography or painting rather much advanced then both. Photography records amplitude and wavelength but a hologram records both the phases and amplitudes of the light waves and effects, the whole “light field” reflected by an object. Some holograms also record wavelength that bring out the colored holograms. Colored holograms are often just monochromatic- usually green or red.
Finally, by the reflection of light holograph receive the ethereal image of the “real object” in its unique three-dimensional state.
Holograms have “parallax” so there appears a difference in the apparent position of an object viewed along two different lines of sight. The different vision of a hologram that we observe from each of our eyes creates the three dimensional effect. Therefore, the viewer can change their view point in front of a hologram and perceive the moving image as if they were looking at the original object itself.
The use of holography is not only to record images but it is getting used to store optical information. Two of the most commonly used data storage places in media are CD and DVD. These have major common aspect of laser technology. They both rely upon laser technology for the functionality and incorporate diffraction grating with the light that reflects from them. The data get encoded because of the differences in the reflected light from the upper surface of the discs. Another application of the same technology that of the holography exists in the scanners used to detect the prices of items from barcodes at updated supermarket outlets.
What is Holograms ?