The Cathode Ray Tube is an optoelectronic device. That is it converts electrical signal into video signal. Physically it is a large, hard and evacuated glass tube.
In most optical devices, it posses most of the places. Actually it is the heart of an oscilloscope and is very similar to the picture tube of Television Set, Computer Monitor etc. with a view to saving space in TV set it is designed with a narrow neck and a large deflection angle. In the narrow neck it contains most of the important components for processing the signal. The tubes are usually designated by the maximum deflection angle and the length along the diagonal of the screen.
CRT has two main parts.
1) Base/Low voltage side (<1 KV)
2) Anode/High voltage side (> several KV)
The base or low voltage side also contains the following parts:
1) Electron Gun
The grids are as follows:
1) Control grid
2) Screen/Accelerator grid
3) Suppressor grid
4) Focus grid
Within a chart the Cathode Ray Tube may be represented as follows: