Patent attributes
A small, inexpensive three-dimensional image display having a structure for displaying a color three-dimensional image sharply even if a low-resolution spatial optical modulating element is used. The three-dimensional image display has an illumination light source unit, a transmission spatial optical modulating element, a lens, and a mask. The illumination light source unit includes three point light sources outputting illumination light components having wavelengths (red, green, blue) different from one another. The point light source outputting the blue illumination light component of the shortest wavelength is disposed in position B(0, 0) on the optical axis of an illumination optical system, the point light source outputting the red illumination light component is disposed in position R(xr, 0), and the point light source outputting the green illumination light component is disposed in position G(xg, 0). An aperture section of the mask is disposed in the region where the zero-order diffracted waves of the reproduction light components of the three wavelengths after subjected to wavefront conversion by the lens are superposed on one another. The illumination optical system determines the direction of incidence of each of the illumination optical components of the three wavelengths on the spatial optical modulation element.
