3D Visual Communications

3.5 Recent Advances in Hologram System Study

Holographic 3D display is a type of display device to reconstruct the optical wave field such that the reconstructed 3D light beam can be seen as the physical presentation of the original object. The difference between conventional photography and holography is that photography can only record the amplitude information for an object but holography attempts to record both amplitude and phase information. Knowing that current image recording systems can only record the amplitude information, holography needs a way to transform the phase information such that it can be recorded in an amplitude-based recoding system.

Figure 3.10(a) illustrates the principle of hologram recording, which uses a coherent light beam. The light is reflected by a mirror as a reference beam and scattered from the object as the object beam. The interference between the reference beam and the object beam is recorded on the photographic plate as a hologram. When the hologram is illuminated by the original reference beam as shown in Figure 3.10b, the reference beam will be diffracted by the hologram to create a light field which closely approximates to the scattered beam from the object in phase, direction, and intensity. In other words, the light field is reconstructed from the observer's point of view, even the original object does not physically appear in its original place. The holography indeed provides a true 3D image reconstruction.

For digital holography, the ...