Hologram

Holography

The phenomenon of constructing a 3 dimensional image of an object using a laser beam is called Holography. In holography, the laser beam records the phase and amplitude of wave into the holographic plate . This gives a 3 dimensional image of the object.

Construction of Hologram

The object beam and reference beam are superimposed on a holographic plate to form an image called hologram.

Working :

A monochromatic source of laser is made to fall on a beam splitter with the help of a condensing lens (C). The beam splitter splits the incident beam into two beams :
i) reference beam ii) Object beam

The reference beam will directly fall on a holographic plate and the object beam after gets scattered by the object will fall on the holographic plate.

Therefore the two beams i.e the reference beam and object beam will interefere with each other and the interference pattern is recorded on the holographic plate. This on developing and processing we get a hologram.



2 Reconstruction of Hologram :

During the reconstruction process, the object is first removed and the laser beam is switched on. The laser light will act as a reading beam. This reading beam is made to fall on the hologram as shown.

Now, due to diffraction the observer can clearly see a 3- dimension. The condition for reconstruction of hologram :

i) The laser beam used for construction of hologram must be used in reconstruction process also.
ii) The table used for reconstruction must be of shockproof.