A stereoscopic observation apparatus is disclosed that includes an image projector that projects left and right eye images to an image surface, with the images being substantially overlapped at the image surface. The images may be viewed auto stereoscopically by virtue of an imaging element having positive optical power that conjugates the apertures to observation exit pupils. A holographic optical element that has little or no optical power is positioned at or near the image surface for the purpose of dispersing the light in the non-zero diffracted orders. The amount of dispersion caused by the holographic optical element over the wavelength range 450 nm-650 nm for diffracted light of the first order is less than or equal to one-half the angular amount that each first-order diffracted beam is diffracted from the direction of propagation of the zero-order beam that passes straight through the holographic optical element.
Three-dimensional observation apparatus