Infrared night vision device is a military night vision device using photoelectric conversion technology. It is divided into active type and passive type: the former uses an infrared searchlight to illuminate the target and receives the reflected infrared radiation to form an image; the latter does not emit infrared rays and relies on the infrared radiation of the target itself to form a "thermal image", so it is also called "thermal image". instrument". The infrared night vision devices sold on the market are all active. Passive infrared night vision devices are generally not called night vision devices, but have been renamed thermal imagers.