Meaning of Holography
The word holography originates from the Greek words “holos” (complete) and “graphos” (writing). Thus, it is the technique to record the complete picture of an object. The technique was proposed by Gabor in 1947.
An ordinary photograph records the two-dimensional image of the picture because it records only the amplitude or intensity distribution. But in the holography technique, both, the intensity as well as phase of the light wave is recorded.
In holography, the light waves reflected from an object are recorded. These light waves consist of intensity and phase and the record is called a hologram. The hologram has no resemblance to the original object but it contains all the information about the object in an optical code.
The formation of the hologram is done by a process called the recording process. The formation of three- a dimensional image from a hologram is done with a process called the reconstruction process.
Thus holography consists of two processes :
I Recording of hologram
II Reconstruction of image
Note: Next time I will discuss these 2 processes in detail.