|Cathode Ray Tube -- Color
The color CRT has three sets of color phosphorous laid down on the inside of the inside of the CRT. These are laid down in a specific pattern, which defer from manufacturer to manufacturer, but the one well be using the very common one, the triad. As you can see from the image
|the triad is made up of one red phosphor dot, one green phosphor dot, and one blue phosphor dot, arranged in a triangular pattern.
At the back of the CRT there a three sepatrate electron guns, one each for the RG and B information. Close to the front of the tube is a thin metal mask which has tiny holes in it arranged in such a way that only the red electron beam can strike a red phosphor, same for both other colors. These phosphors are so small and close together that they cannot be seen as separate and distinct unless they are looked at under magnification. Thus, when they are struck by the electron beams, their colors blend to produce the composite color that is the final result.