Detailed technical performance of night vision equipment
When electrons pass through a pipeline, the atoms in the pipeline release similar electrons, which are multiplied by the original number of electrons by a factor (approximately several thousand times). This can be accomplished using microchannel plates (MCPs) inside the pipeline. A microchannel plate is a miniature glass disk containing millions of micro pores (microchannels) inside, made using fiber optic technology. The microchannel plate is in vacuum and metal electrodes are installed on both sides of the disc. The length of each microchannel is about 45 times its width, and its working principle is similar to that of an electronic amplifier.
When electrons from the photocathode strike the first electrode on the microchannel plate, they accelerate through the glass microchannel under the high voltage of 5000 volts between the two electrodes. When electrons pass through microchannels, thousands of electrons in the channel are released, a process known as cascade secondary emission. In short, the original electrons will collide with the side of the microchannel, and the excited atoms will release more electrons. These new electrons will also collide with other atoms, resulting in a chain reaction where only a few electrons enter the microchannel while thousands leave. An interesting phenomenon is that the microchannels on MCP have a small tilt angle (about 5-8 °), which is not only to trigger electron collisions, but also to reduce ion feedback and direct optical feedback from the output phosphor layer.
Night vision imaging images are known for their eerie green luster.
At the end of the image enhancement tube, electrons collide with a screen coated with phosphorescent material. These electrons will maintain their relative positions when passing through microchannels, ensuring the integrity of the image, as the arrangement of electrons is the same as that of the initial photon arrangement. The energy carried by these electrons will excite the phosphor and release photons. These phosphorous materials generate green images on the screen, which has become a major feature of night vision devices. Through another lens called an eyepiece, a green phosphorescent image can be observed, and the eyepiece can also be used to magnify the image or adjust the focal length. NVD can be connected to electronic display devices, such as displays, or images can be directly observed through an eyepiece.
