Abstract: The invention relates to viewers intended for the observation of visual pictures.In order to cause the angular convergence of visual radii to vary, at the level of an observer's eyes (G) and (D), when viewing pictures (1) and (1'), two pairs of prisms (2) and (2'), (3) and (3') are interposed on the optical paths, the first pair being in part reflective and transparent, thus creating a common beam (7) (7'), where a single converging lens (8) makes it possible, by displacement of its optical center (C), along the directions (17), to vary the angular observation convergence.Applications consist, in particular, in examining stereoscopic images.

Abstract: A system for adjusting the relative position of the optical unity axes used in viewing images of associated couples. In order to permit a satisfactory cerebral fusion when two images present a displacement in their positioning, a viewer is equipped within the optical block having the cylindrical and lateral surfaces and co-operating with surfaces of complementary forms and of the baseplate. Ocular circles define the position of the observer's eyes. The invention is particularly useful for projection onto a screen of pairs of stereoscopic images.