The electrons pass through a light intensifier tube and are projected on a phosphorous screen. Since the electrons carry no color information, night vision devices have monochromatic screens. Since the human eye is most sensitive to green light, green is the most often used screen color. Using night vision technology, the light from a dim star in a situation that we may perceive as "pitch black" to the naked eyecould be enough to illuminate an entire field.

First used in World War II and extremely valuable to troops in the Vietnam War, night vision technology has continued to evolve over the past 70 years. Because of this, devices are rated as Generation 1, 2, 3, and sometimes 4. GEN 1 devices are the most popular and are excellent for personal outdoor use—observing nocturnal wildlife, boating, and back country hiking, for example— and will produce light amplification of around 1,000x the available ambient light. Costs increase dramatically for later generation technology, which is most often used for law enforcement and military applications.

GEN 1 devices may produce a faint high-pitched noise when turned on, and will glow green for a few moments when turned off.