Duboscq patented the stéréoscope on 16 February 1852, with mention of a projection variation. On 12 November 1852 he applied for an addition certificate to include his "Stéréoscope-fantascope, ou Bïoscope". Basically a combination of Plateau's standard fantascope and the stereoscope, it used two small mirrors in different angles next to each other that reflected stereoscopic image pairs (printed above each other on the stroboscopic disc) into the stereoscope viewer. Of three planned variations only one was actually produced, but it wasn't very successful commercially. Only one extant disc is known, from the Joseph Plateau estate kept at the Ghent University. It has stereoscopic sets of a sequence of photographic images of a machine in action. No original viewing device has resurfaced, but parts of it are known from an illustration in an 1853 advertisement.