Early Color Television
Baird Electronic Color System (1942-45)
This system was based on designs evolved by John L. Baird. In 1943, he designed a two color system, with two images produced on the face of a CRT. Lenses then converged the images.
Inside the viewing tube is a transparent screen having parallel ridges on the side toward the viewer and flat on the opposite side. There are three electron guns whose beams are modulated by the three color band signals. The beam from one of these guns can impinge on only one side of the ridges. This side is coated with a phosphor emitting the color band which is to be reproduced by the corresponding gun. The second gun can send its beam only to the opposite side of the ridges, this side being coated with phosphor emitting the second color band. The beam from the third gun strikes the flat surface of the screen, which carries a phosphor emitting the third color band. The third color, produced on the back of the screen, shows through the transparent supporting material and mixes with the other two color band produced on the sides of the ridges. The ridges are very narrow and closely spaced. Two of the guns are in such positions that their beams travel different distances to opposite sides of the screen. (Information and pictures courtesy of Rick Plummer)
Here is some additional information, courtesy of Stu Andrews:
From the British "Journal of The Television Society", September 1941
Courtesy of Steve Dichter