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How Do Night Vision Goggles Work?

Mar 02, 2021 | 03:52 pm 469 0
How Do Night Vision Goggles Work?

You've definitely watched at least one action or spy movie. To see in the dark, special agents or cool policemen wore night vision goggles. You too can buy a couple of these accessories, but let's first figure out How Do Night Vision Goggles Work and what they can be used for.

How Do Night Vision Goggles Work?

Before moving on to the theoretical part of the article, let's remember what are the light and the Electromagnetic Spectrum (ES). All objects emit light in different amounts. Our eyes can only perceive a small fraction of this radiation. But there are many more different types of radiation which we can’t see without special equipment.

ES is the whole range of existing light, our eye can catch only its central part. The central color part includes all the colors and shades of the rainbow, ranging from red to purple. Notice that red starts our visible spectrum, and infrared light comes just before it. Infrared means "before red," and it is at the edge of our visible spectrum.

Although we cannot perceive infrared radiation, night vision goggles can see it. It's time to find out how they work. This device captures infrared light emitted by objects. Good goggles are capable to catch almost all available light. Moonlight or starlight will be enough for they provide a clear image. So, how the emitted light turns into a visible picture:

    • Lenses capture light and direct it to the photocathode. The photocathode is one of the main parts of the assembly. It converts photons into electrons.

    • Electrons enter the image intensifier tube. Here their number increases several hundred or thousand times. The more electrons are obtained, the better and sharper the final image will be.

    • An avalanche of electrons hits the phosphor screen, which converts them into a visible image.

The more stars in the sky and the brighter the moon shines, the more light the lenses can capture. Under good conditions, goggles can see objects at a distance of 200 yards. 

What two types of technology are used for night vision goggles?

Image enhancement

Goggles work according to the principle described above – capturing all possible light. Such a device can see in almost complete darkness, an infrared beam is used for additional illumination. Gen 3 models capture the maximum amount of light, due to which the image will be very clear and bright. They have a good viewing range and can show distant objects without darkening the corners. A big plus of such accessories is that they catch almost all objects, immovable targets, and so on. In such goggles, you can easily move through the field, bushes, or forest in the dark. Also, such a device is used by hunters during night hunting, wildlife watchers to observe the life of nocturnal animals, security organizations to protect the territory.

This device also has its cons. For example, you will not see camouflaged objects, standing still animals, objects that are hidden behind a wall, a tree, or in the foliage. Also, in bad weather, when it is raining, fog, or snow outside, such goggles will be useless.

Thermal Imaging

For such devices, light is not needed at all, because they can work in complete darkness. Thermal Imaging reacts to heat. Every object, alive or not, emits heat. People and animals emit a lot of heat, buildings, stones, trees emit it too, but rather less. Thermal Imager is capable of capturing heat from 0.01 degrees and higher. The image on the screen is displayed not in the usual format, but the form of colored spots. In newer and more expensive models, the image is displayed in all colors of the rainbow. The warmer the object, the brighter and lighter the color is. Older or less expensive models show images in different shades of gray.

The thermal imaging has a good viewing range, it can see all warm objects at a big distance. Thermal imager sees through smoke, rain, snow, smog, catches warm radiation through thin doors and walls, tree foliage, or bushes. With the help of such a device, rescuers find people during a fire or natural disaster, locked in a room, under the snow, etc. This is an indispensable accessory for the protection of the territory at any time of the day.

But there are also a few cons. First of all, this is the price. You have to pay several thousand dollars for one pair of thermal vision goggles. It will be difficult for you to understand the color spots from the first time. The device does not see cold objects, which temperature is below 0.01 degrees.

In general, any type of NV goggles is pretty cool. This device leaves your hands free, you can easily move around and even drive a car. Choose the functionality, model, size, and generation to your taste, but any option will be the best.

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