Night vision devices based on the light amplification：They work in the visible and near infrared (IR) light range and need some ambient light to work properly. They use what is called an image intensifier tube (IIT) and the resulting image is a shade of green.
Another night vision technology that does not require ambient light is thermal imaging. This technology detects the temperature difference between the background and foreground objects. It is known that all objects emit infrared energy as a function of temperature, and the higher the temperature, the more infrared radiation it emits. NVDs based on this technique collect infrared radiation (3-light wave range of 30µm) from objects in the scene and create electronic images. Since these devices do not depend on reflected ambient light, they are completely independent of ambient light level conditions. They can also penetrate smoke, fog and haze
Gen2: Micro-optical pathway plate (MCP) photocathode S-25 (S-25/S-20/S-20R photocathode) is used, the photosensitivity (photosensitivity) is 240-400µA/lm, 25 000 ~ 50 000 times gain (luminance gain) can be obtained, the resolution of the center ( resolution) varies between 28-32lp/mm. Service life increased to about 2500 to 5000 hours, Gen2 mainly work in the 780-850nm wavelength range, they are more tolerant of urban lighting than the third generation system.
Gen2+: The light amplification (luminance gain) is about 25 000 to 35 000 times. The photocathode sensitivity (photosensitivity) of the second generation + is 500-600µA/lm, and that of the super second generation is 600-700µA/lm. The central resolution (resolution) of the second generation + varies between 32-45lp/mm, and that of the super second generation is 45-60lp/mm. The lifetime of these generations is about 10,000 hours.
Gen3: based on a new photocathode coating. Gallium and arsenic elements (GaAs) Gen3 tube with almost no distortion, Gen3 can produce more than 800µA/lm in the spectral region from 450 to 950 nm. the resolution of the center varies between 45-64 lp/mm. This generation has a lifetime of up to 10 000 hours. The magnification of light is about 50,000 times.
