Engineering Physics

12.4 Reconstruction of image from a hologram

As shown in Fig. 12.2, the hologram is exposed to the laser beam [that used during construction or identical to the reference beam used for construction] from one side and it can be viewed from the other side. This beam is known as reconstruction beam. The reconstruction beam illuminates the hologram at the same angle as the reference beam. The hologram acts as a diffraction grating, so constructive interference takes place in some directions and destructive interference takes place in other directions. A real image is formed in front of the hologram and a virtual image is formed behind the hologram. It is identical to the object and hence it appears as if the object is present. The three-dimensional ...