Viewer

From Memory Alpha, the free Star Trek reference

Viewers are the optical and visual devices and screens used aboard starships, such as viewscreens and scopes. It is a general term for equipment found among numerous races. Viewers come in a variety of sizes, from desktop units to wall-mounted versions such as that commonly found on the main bridge of a starship. Some viewers are equipped to generate three dimensional images. Where No Man Has Gone Before (episode)