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use of acusto-optic material and optically addressed spatial light modulators [55].
Pure hologram technology utilises 3D information to calculate a holographic pat-
tern [56], generating true 3D images by computer control of laser beams and a
system of mirrors. Compared to stereoscopic and multi-view technologies the
main advantage of a hologram is the good quality of the generated 3D image.
Practical application of this technology today is hampered by the huge amount of
information contained in the hologram which limits its use to mostly static 3D
models, in limited size and narrow viewing angle.
5.3 HoloVizio Type Light-Field Displays
Such displays follow hologram geometry rules, however direction selective light emis-
sion is obtained by directly generating the light beams instead of interference. In this
way the huge amount of redundant information present in a hologram (phase, speckle)
is removed and only those light beams are kept which are needed to build up the 3D
view. Each point of the holographic screen emits light beams of different colour and
intensity to the various directions in a controlled manner. The light beams are gener-
ated through a specially arranged light modulation system and the holographic screen
makes the necessary optical transformation to compose these beams into a 3D view.
The light beams cross each other in front of the screen or they propagate as if they
were emitted from a common point behind the screen, as shown in Fig. 13. With
proper control of the light beams viewers see objects behind the screen or floating in
the air in front of the screen just like with a hologram.
Fig. 13
Principle of HoloVizio light-field displays
