The advent of lasers has made the art of holography possible. Photography can be thought of as a new approach to the problem of generating images. An ordinary photograph represents a two dimensional recording of a three dimensional scene. The emulsion on the photographic plate is sensitive only to intensity variations. In this process the phase information carried by the electromagnetic wave scattered from the object is lost. Since only the intensity pattern is recorded, the 3D character of the object is lost. The principle behind the holograph is “During the recording process one superimposes on the scattered wave (emanating from the object) another coherent wave (called reference beam) of the same wavelength”. These two waves interfere in the plane of the recording medium and produce interference fringes. This is known as recording process.

HOLOGRAPHY

• Holography is a technique of producing 3D images.
• In Holography, both intensity and phase of light waves are recorded.

PHOTOGRAPHY

• Photography is a technique of producing 2D image.
• In a photography, only intensity of light waves are recorded