Hinged lid

The hinged lid in a stereoscope is responsible for admitting and reflecting light. By opening the lid, light can enter the housing of the stereoscope, which is necessary for illuminating non-transparent stereoviews, such as paper stereoviews and daguerreotypes.

In early stereoscopes the hinged lid was fitted with reflective foil, and later with a mirror, allowing the light to be directed and intensified.

The hinged lid was mainly used in boxed-type and chain-based stereoscopes designed for non-transparencies, such as paper stereoviews. In viewers intended exclusively for glass stereoviews, the hinged lid as a light-regulating construction is absent.