using refractive optical elements, e.g. prisms, in the optical path between the images and the observer

Full Title

Optical systems or apparatus for producing three-dimensional [3D] effects, e.g. stereoscopic images (in microscopes G02B21/22) > by providing first and second parallax images to an observer's left and right eyes > Stereoscopes providing a stereoscopic pair of separated images corresponding to parallactically displaced views of the same object, e.g. three-dimensional [3D] slide viewers > using refractive optical elements, e.g. prisms, in the optical path between the images and the observer