Final answer:
In an image intensifier tube, electrons are accelerated by an anode due to photo-emission and focused by electrostatic lenses.
A photomultiplier can make the output current proportional to the energy of the incoming light, not necessarily emitted in exponential proportion to the intensity of fluorescent light.
The correct statement is: do so by photo-emission or photoelectric emission
Step-by-step explanation:
The electrons emitted by the photo-cathode in an image intensifier tube are indeed accelerated by the accelerating anode, a process that is the result of photo-emission or the photoelectric effect. These electrons are then focused, with some geometric distortion, by electrostatic lenses.
This focus is important for maintaining the quality of the image being intensified. In terms of emission in relation to fluorescent light, while the initial question suggests that the emission is exponential, it is more accurate to say that the final output current in a related device like a photomultiplier can be made proportional to the energy of the light entering the tube.
This is based on the amplification of the photoelectric effect, where electrons are emitted by light striking a metal plate and subsequently multiplied. Such technology has wide applications, including in scintillators used for detecting and analyzing particles, and in medical imaging technologies like image intensifiers.