What component is primarily used to focus the electron beam in a fluoroscopy system?

In a fluoroscopy system, electrostatic lenses are utilized to focus the electron beam. These lenses are crucial components that manipulate the path of electrons emitted from the photocathode toward the output phosphor. By applying electric fields, electrostatic lenses can finely adjust the trajectory of the electrons, ensuring that they converge at a specific point where the output phosphor is located. This focusing is essential for producing a clear and focused image on the display system.

The role of the photocathode is to convert incoming light (from the input phosphor) into an electron beam, but it does not focus the beam. The input phosphor itself serves as the initial point of interaction, converting x-ray photons into visible light, which is then directed to the photocathode. The output phosphor, conversely, converts the electron beam back into visible light for imaging purposes but does not contribute to beam focusing. Thus, the electrostatic lenses are the key component responsible for directing and concentrating the electron beam effectively within the system.