A stereoscope is a device used to view stereo photographs, also known as stereographs or stereo cards, in three dimensions. It typically consists of a viewer with two eyepieces and a set of lenses or mirrors that present two offset images to each eye. These images, when viewed together through the stereoscope, create the illusion of depth and dimensionality.
Stereoscopes have been used since the 19th century and were popular during the Victorian era as a form of entertainment and education. They allowed viewers to experience scenes from around the world, historical events, and everyday life in three dimensions.
There are various types of stereoscopes, including handheld viewers, tabletop viewers, and larger models designed for public viewing. Some modern stereoscopes are even designed to work with smartphones, allowing users to view stereo images using their mobile devices and a compatible viewer attachment.