Photographic plate
From Just Solve the File Format Problem
Before photographic film, there were photographic plates. They were plates of glass (or, even earlier, copper plates known as "daguerreotypes" after their inventor) coated with photographic material so that they could hold pictures just like film negatives. They were in use in the 1800s, but faded out of use in the 20th century as film caught on; plates were much bulkier and more fragile. Photographic plates remained in use by some professional photographers as late as the 1970s and by astronomers even longer (into the 1990s), since they were useful for wide-field imaging.
