Electrostatic deflection

The CRT in this Tektronix vectorscope uses electrostatic deflection, which only allows for small angles and requires a very deep tube.

In electromagnetism, electrostatic deflection refers to a way of modifying the path of a beam of charged particles by the use of an electric field applied transverse to the path of the particles. The technique is called electrostatic because the strength and direction of the applied field changes slowly relative to the time it takes for the particles to transit the field, and thus can be considered not to change (be static) for any single particle.