(from the article `television`) ...and by the mid-20th century they were replaced by vacuum tubes, which utilized an electron beam to scan an image of a scene that was focused on a ... ...nose of the bomb. The guidance system consists of sensors to detect the target and some means of adjusting the bomb`s fins or wings in order to ... ...
[n] - a tube that rapidly scans an optical image and converts it into electronic signals
television pickup tube noun a tube that rapidly scans an optical image and converts it into electronic signals