Abstract: A double-stage phase-diversity receiver divides one signal into a plurality of signals. These divided signals are mixed with first-stage local oscillation signals having predetermined phase relations to thereby provide a plurality of electrical baseband signals. These electrical signals are up-converted by using second-stage local oscillation signals having a predetermined phase relation. The up-converted IF signals are added, and are then demodulated by a heterodyne scheme.

Abstract: In the disclosed three-dimensional image display apparatus, a projecting system projects images having parallax information onto a screen. The screen is composed of a plurality of corner reflectors each composed of three intersecting reflecting surfaces, two of which are flat and intersect at right angles to each other in a line perpendicular to a parallax direction of said images and the other one of which is cylindrical with respect to said parallax direction and at right angles to said two surfaces to be placed in optically identical angular relation to said two surfaces. A mask shields the area around the projecting system so that only light reflected transverse to the parallax can be viewed.