When it comes to night vision devices, most people think of image enhancement technology. In fact, image enhancement systems are commonly referred to as night vision devices (NVDs). Inside the NVD is an image intensifier tube that captures and amplifies infrared and visible light. Here's how an image enhancement system works:

A traditional lens called an objective captures ambient light and some near-infrared rays.

The collected light is sent to the image intensifier tube. In most NVDs, the power supply system for the image intensifier tube draws power from two N-Cell or "AA" batteries. The pipe will output a high voltage of about 5000 volts to the picture tube assembly.

The image intensifier tube has a photocathode that converts photons into electrons.

When electrons pass through the pipe, the atoms in the pipe will release similar electrons, the number of which is the original number of electrons multiplied by a factor (about several thousand times), which can be done using the microchannel plate (MCP) in the pipe. Work. A microchannel plate is a tiny glass disk containing millions of tiny pores (microchannels) inside, fabricated using fiber optic technology. The microchannel plate is in a vacuum, and metal electrodes are mounted on both sides of the platter. Each microchannel is about 45 times its width and works like an electronic amplifier.

When electrons from the photocathode strike the first electrode on the microchannel plate, the electrons are accelerated through the glass microchannel by a high voltage of 5,000 volts between the two electrodes. As electrons pass through the microchannel, thousands of electrons in the channel are released, a process called cascaded secondary emission. In short, the primordial electrons hit the sides of the microchannel, and the excited atoms release more electrons. These new electrons also hit other atoms, creating a chain reaction that results in a handful of electrons entering the microchannel and thousands leaving the microchannel. An interesting phenomenon is that the microchannels on the MCP have a slight tilt angle (about 5-8°), which is both to induce electron collisions and to reduce ion feedback and direct optical feedback from the phosphor layer at the output.

Night vision images are notable for their eerie green sheen.

At the end of the image intensifier tube, the electrons hit a screen with a phosphorescent coating. The electrons maintain their relative positions as they pass through the microchannel, which ensures a good image because the electrons are arranged in the same way that the photons were arranged in the first place. The energy carried by these electrons causes the phosphor to reach an excited state and emit photons. These phosphors produce a green image on the screen, which has become a feature of night vision goggles. Through another pair of lenses called eyepieces, the green phosphorescent image can be observed, and the eyepiece can be used to magnify the image or adjust the focus. NVDs can be connected to electronic display devices, such as monitors, or to observe images directly through the eyepieces.