1. Photoelectric conversion stage

Photon absorption: The work of an image intensifier starts with a photocathode. The photocathode is a special material, usually made of alkali metal compounds (such as antimony-potassium-sodium-cesium compounds). When weak light (such as moonlight, starlight) shines on the surface of the photocathode, the electrons in the photocathode absorb the energy of the photon. According to Einstein's photoelectric effect, when the energy of the photon is greater than the work function of the photocathode material, the electron will escape from the surface of the photocathode, and this process converts the light signal into an electronic signal.

Electron emission: The number of electrons that escape is related to the number of photons that shine on the photocathode. In a dim light environment, although the number of photons is small, as long as there is enough photon energy, corresponding electrons will be emitted. These electrons form an electronic image corresponding to the input light image, but the electronic image is still very weak at this time and needs further processing.

2. Electron acceleration and focusing stage

Electron acceleration: The electrons emitted from the photocathode are accelerated by the accelerating electric field. The accelerating electric field is generated by a series of electrodes (such as focusing electrodes and anodes) inside the image intensifier. The electrons gain energy and speed up under the action of the electric field force. This process is like "injecting power" into the electrons, allowing them to hit the next target more forcefully.

Electron focusing: At the same time, in order to ensure that the electrons can accurately form a clear image on the fluorescent screen, the image intensifier will also focus the electrons. Through a carefully designed electric field distribution (similar to the principle of optical lenses focusing light), the electrons are guided and gathered at a specific position on the fluorescent screen. This process ensures the clarity and accuracy of the electronic image, so that the final light image can truly reflect the details of the original scene.

3. Fluorescence conversion stage

Electrons hit the fluorescent screen: The accelerated and focused electrons hit the fluorescent screen with higher energy. The fluorescent screen is made of fluorescent materials (such as cadmium zinc sulfide, etc.). When high-speed electrons hit the fluorescent screen, the atoms in the fluorescent material will be excited.

Photon emission: The excited atoms will jump back from the high-energy state to the low-energy state and emit photons. This process is the process of converting the electronic signal into a light signal again, and because the electrons gain energy during the acceleration process, the number of photons emitted is greater than the number of photons that initially illuminated the photocathode, thereby achieving image enhancement. In the end, the user sees an image that is brighter and clearer than the original low-light scene.