Usually in auto stereoscopic display, there are two problems. The first problem is that large image display is
difficult, and the second problem is that the view zone (which means the zone in which both eyes are put for
stereoscopic or 3-D image observation) is very narrow. We have been developing an auto stereoscopic large video
display system (over 100 inches diagonal) which a few people can view simultaneously1,2. Usually in displays that
are over 100 inches diagonal, an optical video projection system is used. As one of auto stereoscopic display systems
the hologram screen has been proposed3,4,5,6. However, if the hologram screen becomes too large, the view zone
(corresponding to the reconstructed diffused object) causes color dispersion and color aberration7.
We also proposed the additional Fresnel lens attached to the hologram screen. We call the screen a “hybrid
hologram screen”, (HHS in short). We made the HHS 866mm(H)×433mm(V) (about 40 inch diagonal)8,9,10,11. By
using the lens in the reconstruction step, the angle between object light and reference light can be small, compared to
without the lens. So, the spread of the view zone by the color dispersion and color aberration becomes small. And also,
the virtual image which is reconstructed from the hologram screen can be transformed to a real image (view zone). So,
it is not necessary to use a large lens or concave mirror while making a large hologram screen.