Night vision goggles

Night Vision Goggle

Experimental night vision goggles. Night vision goggles (NVG) are a type of optical instrument that allows one to see in the dark. They are most often used by the military.

three common types of night vision goggles:

Passive night vision goggles — these pick up any light in the given area and amplify it several thousand times using an image intensifier.

Active night vision goggles — these project infrared light (the same type used by a remote control), and produce an image from the light reflected back.

Heat-sensing or infrared goggles — these show anything that emits normal heat radiation in the given area.

Generation I Night Vision devices use an intensifier tube that amplifies ambient light by accelerating electrons and striking a phosphor surface just like a Television. Generation II night vision devices add a micro-channel plate that multiplies the number of electrons before they impinge on the phosphor screen, thus increasing gain; Generation III Night Vision goggles, monoculars and scopes further add a Gallium Arsenide photocathode which creates significantly more photoelectrons than Gen II night vision devices . Generation IV Night Vision is now offered by ATN. Generation II and III night vision devices offer greater light amplification, they are definitely better than Generation I, but a price beyond the reach of most buyers. Modern Generation I Night Vision devices are high quality and provide light amplification adequate for most recreational activities camping, hiking, fishing, boating, and nature viewing, and for many professional uses such as surveillance, search and rescue, and property management.
Why use a Night Visions Devices Instead of a Flashlight?

Two reasons: 1) Night Visions Devices make possible a quality of seeing that is far superior to flashlights. They provide your eyes with a light amplification tool that gives you much more night vision sensitivity than many nocturnal animals. 2) See, without being seen. Think of the advantages of seeing without intruding when you are trying to find your way around an unlit campground. Property owners can observe nocturnal criminal activity. Nature lovers can observe animals without startling them. If you suspect a prowler is nearby, you can spot the “perpetrator” without alarming him and safely call the police.

Night Vision Goggles (NVG) in War
During the history of war, operations at night were significantly, if not totally avoided. Typically, soldiers fighting at night had to resort to artificial illumination, e.g., at first fire and later with light sources such as searchlights. The use of light sources on the battlefield had the detrimental result of giving away tactical positions and information about maneuvers. The advent of new technologies initially in the 50’s and continuing to the present changed this. Engineers and scientists at the USA Army’s Communications-Electronics Command (CECOM) Night Vision & Electronic Sensors Directorate (NVESD) discovered ways to capture available electro-magnetic radiation outside that portion of the spectrum visible to a human eye and developed equipment to enable tan American soldier to fight as well at night as during the day and to “Own the Night”.

Thermal Forward-Looking Infrared (FLIR) detectors – sometimes called “sensors” – work by sensing the temperature difference between an object and its environment. FLIR systems are installed on certain combat vehicles and helicopters.

NVGs are electro-optical devices which can intensify (or amplify) existing light instead of relying on a light source of their own. Image intensifiers capture ambient light and amplify it thousands of times by electronic means to display a night scene via a phosphor display such as night vision goggles. This ambient light comes from the stars, moon or sky glow from distant manmade sources, such as cities. The devices are sensitive to a broad spectrum of light, from visible to infrared (invisible). Users do not look through NVGs, you look at the the amplified electronic image on a phosphor screen.

Light enters the NVG through an objective lens and strikes a photo cathode powered by a high energy charge from the power supply. The energy charge accelerates across a vacuum inside the intensifier and strikes a phosphor screen (like a TV screen) where the image is focused. The eyepiece magnifies an image.

An NVG phosphor screen is purposefully colored green because a human eye can differentiate more shades of green than other phosphor colors. Like cameras, NVGs have various image magnifications. The distance at which a human sized figure can be clearly recognized under normal conditions (moon and star light, with no haze or fog) depends on both the magnifying power of the objective lens and the strength of the image intensifier. The maximum viewing range is 100 feet to 400 feet.

Foreign terms for Night Vision Goggle NVG

Nachtsichtgerät = German

Nattkikare = Swedish

Noktowizor = Polish

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