THREE-DIMENSIONAL IMAGE DISPLAY AND THREE-DIMENSIONAL IMAGE DISPLAYING METHOD

摘要

A three-dimensional image display having a simple structure enabling display of a high-quality reproduced image by effectively using the focal adjustment function of the eyes of the observer. The three-dimensional image display comprises a spatial optical modulating element, a front-illumination optical system, and a lens serving as a reproduction image conversion optical system. An image is reproduced on the back focal plane of the lens by the diffraction of specific order by the spatial optical modulation element. At least either the luminescent spot distance between the luminance spots constituting a target reproduced image to be displayed or the initial phase value of each luminance spot is set in such a way that peaks of reproducing light reaching within the region where the reproduced image can be observed are present in multiple positions. Therefore, a hologram by which the target reproduced image can be displayed is given to the spatial optical modulation element. The illuminating light incident on the spatial optical modulation element is amplitude- or phase-modulated in each pixel. To the modulated light, that is, reproducing light, wavefront transformation is applied by the lens and a reproduced image is formed. When the observer positions the pupils of the eyes near the aperture of a mask, the observer can view the displayed reproduced image through the aperture and a semitransparent mirror.