Stereoscope - the device for examining pair (stereoscopic) drawings order to obtain three-dimensional images. In stereoscope artificially reproduce the conditions of the so-called binocular parallax underlying perception of depth of space. The human eye consider the real object from different points of space, so on the retina resulting images of the object that differ somewhat from each other. This feature binocular vision reproduced in stereoscopic pictures. The left and right images stereoscope presented in such a form in which they are visible to the left and right eye in natural conditions. The merging of these't quite similar pictures in a single whole and gives the impression of three-dimensional images.
The stereoscopes are mirror and lens. Devices are used for the diagnosis and treatment of strabismus (see).