The basic principle of night vision is that the night vision captures with its lens invisible infrared radiation or visible light (natural, stars, the moon or artificial) from the field of vision and then focuses it to the image intensifier tube which subsequently directs this remaining light i.e. photon beam to the multiplier phototube where the photons are converted into electrons.

Further in the microchannels of the image intensifier tube under electro-chemical process and in vacuum they are multiplied several thousand times and directed to the shade covered with a phosphor layer and where the incident electrons are converted back to visible light and image.

We see this resulting intensified image in the eyepiece. The resulting image is usually in shades of green, green-yellow or black-white colours depending on the type of used phosphor.