The term stereoscopy is a word-formation from Greek stereos = space or spatial and skopein = to see. We all know especially well that the term stereo is used when audible effects get mentioned. Whenever one deals for instance with tools that show something, we meet the Greek word skopein in word-formations like telescope, microscope, kaleidoscope, etc.
This term means all methods and techniques for production and reproduction of three-dimensional pictures that are based on the principles of natural seeing with two eyes: because of the interocular distance the left eye sees an object from a slightly other observation point than the right eye. These two — perspectively different — views will be fused in brain to a single spatial perception. In the technique of stereoscopy this process is imitated with two images which perspectively differ from each other in relation to the interocular distance. To create the 3D-effect, these two images, however, must be presented separately to the eyes, so that the left eye only can see the left picture and the right eye only the right one.
The discovery of stereoscopy as such is owned to the versatile physicist Sir Charles Wheatstone who in his time had been professor for experimental natural sciences at the Kings College London. He made several inventions, among them the buzzer and the electrical telegraph. On June 21st, 1838 he held a pioneering lecture On Some Remarkable, and Hitherto Unobserved, Phenomena of Binocular Vision in the presence of the Royal Society. The same year — just before photography got invented — this report was published in the renowned Philosophical Transactions. 1852 followed a second publication for continuation and supplement.
Already soon after the first publication the discovery of stereoscopy triggered off a great interest in it, and it made many notable scientists all over Europe carry out further studies and experiments. In additition, stereoscopy found a general public, because people everywhere enjoyed three-dimensional picture-sets and handy viewers. Contemporaries even jested that it was a stereo mania, and actually, the phenomenon of a mass medium in modern terms was to perceive.