The human eye is sensitive to light of all colors. However, it can distinguish more shades of green than any other color. That’s why night vision goggles are seen with green shades. There are actually three different types of night vision devices. Which type of night vision device is used obviously depends on its application.
Thermal imaging is used in complete darkness. All people, animals, and things give off thermal energy by their temperature. The temperature is represented by different colors. Low light imaging vision devices require that some light be present. They work by intensifying the light signals, like how a speaker amplifies sound. The final device is near infrared imaging. It requires an infrared emitter and an infrared detector. Infrared light is sent out by the emitter and the detector records the picture made.