Television camera tube component noise factors

The signal-to-noise ratio in the video output from a television camera tube equals the signal-to-noise ratio in the optical exposure divided by the product of the noise factors for each of the tube'S components. The noise factor of each component is determined by the amount by which the component increases the rms fluctuation in the number of quanta representing a picture element. The noise factor of the components (e.g., image section photoconductor, electron multiplier, low-velocity scanning beam) is calculated for a variety of components. The component noise factor equations show that: 1) the noise factor of photon-to-electron converters is primarily determined by their quantum efficiency, i.e., by the number of electrons produced per photon, and 2) the noise factor of readout processes decreases as the signal voltage on the target increases, and increases with an increase in energy spread of the reading beam for low-velocity read-out, or of the secondary electrons for high-veloicty readout.