What is the sequence of events that initiates the operation of an image intensifier?

The operation of an image intensifier begins with X-rays striking the input phosphor. When X-rays enter the device, they interact with the input phosphor (usually made of materials like cesium iodide), which then emits light photons in response to that interaction. This is the initial step in the chain reaction that leads to image intensification.

Once the input phosphor emits light photons, these photons then strike the photocathode, converting the light energy into electrons. This subsequent step allows the image intensifier to amplify the signal effectively. The series of transformations from X-ray to light photon to electron is crucial in producing an intensified image that can be viewed on the output screen of the intensifier. The correct sequence highlights the importance of the input phosphor in starting the entire process.