Stereograph

In the 1850s, stereographs became the first mass-produced images sold. When a card with two similar images side by side is viewed through a set of lenses, it creates an optical illusion that gives the impression of a single, three-dimensional image. The earliest stereograph was invented before the advent of photography by Sir Charles Wheatstone, using illustrations. In the following years, the technology was improved upon and came to include photographs. After being exhibited at the 1851 Crystal Palace Exhibition in London, the stereograph grew in popularity and spread internationally.