What Is Night Vision and How Does It Work?

What Is Night Vision and How Does It Work?

What Is Night Vision and How Does It Work?

When we think about what is night vision, all we keep going back to are the stuff in movies or something you would see soldiers from the military are using. We don’t tend to associate night vision with regular folks.

But then again, even though you may have never used any night vision device before, there is this curiosity to know what it is and how it works. So, in this article, we intend to talk at length about what night vision is, the different types of night vision devices, and how it all works in darkness.

What Is Night Vision?

If you search for the definition of night vision, you will most definitely find out that is a kind of equipment that allows people, especially soldiers and pilots, to have better visibility at night or in darkness. So, to put it simply, night vision refers to the ability to see above and beyond the normal boundaries of the visible light.

While we are blessed abundantly with several wonderful abilities, we do lack the ability to see clearly in darkness. Our sense of sight is at its best in the presence of light, or rather, when there is sufficient bright light.

That being said, it is also true that there is always some light present even when it is dark. This is because not all the light is visible to the human eye. In the darkness, there are two different types of light that are present, and these are often referred to as ultraviolet light and infrared light. This is measured in wavelength (nm).

Ultraviolet light falls in the range of 100 to 400 nm, and infrared light ranges from 700 and above. The light that is visible to the human eye is located in the middle of this light spectrum, which is between 400 to 700 nm. The infrared and ultraviolet light falling on either side of the visible light is not visible to the human eye under regular conditions.

So, if we want to view things at night, we can only do so with the help of an external device that can detect and amplify this invisible light and make it visible to us. This is where night vision devices come in.

How Do They Work?

T help you understand better what night vision is, allow us to give you a non-technical answer. Night vision devices have the capability to detect infrared light, which is absolutely invisible to the human eye. Thereafter, undergoing the process of enhancement, this light gets converted into visible light. Do note that the term enhancement does mean magnification.

Now, to give you a more detailed answer, know that when an image in the dark gets captured by the night vision device, which consists of the invisible infrared light photons, this light gets converted into high-energy photons. Afterward, they get multiplied into more electrons before they get converted back into photons of light, making them visible to human eyes.

The result that it provides is several more photons, which in turn have the capability of providing us with ample visible light to see in the dark comfortably.

Active and Passive Infrared Devices

Active infrared devices are the kinds that need an external projection unit. These are commonly referred to as an IR illuminator. Not familiar with this term? Allow us to enlighten you, then.

The IR illuminator is the one responsible for projecting a beam of infrared light that is invisible to an object so that it can capture just about enough of this light, allowing it to be visible in the device. These were considered the original Generation 0 night vision devices that were actively used in World War II. These can still be found today, but typically as an option on passive IR devices.

On the other hand, passive infrared devices, which are known as the Generation I, Generation II, and Generation III night vision devices, make use of infrared light that is available in absolutely a small amount of ambient light. These kinds of ambient light will be available from moonlight and starlight, rather than an IR illuminator.

Different Types of Night Vision Equipment

Night vision devices can be broadly divided into three categories depending on their usage and functionalities. These include the following:


These are typically handheld or mounted on top of a firearm. Scopes are monocular, that is, one eyepiece. Since all the scopes are handheld, they are not worn like goggles and are good when you are trying to get a better look at a particular object and switching back to regular viewing conditions.


Goggles can be handheld as well, but in most cases, these are worn on the head. Goggles are binoculars, that is, two eyepieces. They have either one lens or stereo lens, which will depend on the model.

Goggles are an ideal choice if you need constant viewing, such as when you are moving around in a dark building yet need to be able to see.


Cameras that are equipped with night vision technology is capable of sending images to a monitor for displaying or into a VCR to record. When the desired location needs permanent night vision capability, then these cameras are used. Many modern camcorders have night vision capabilities in-built.

Different Night Vision Applications

Among the most common applications for night vision technology include:

  • Hunting
  • Wildlife observation
  • Security
  • Entertainment
  • Navigation
  • Hidden-object detection
  • Surveillance
  • Law enforcement
  • Military

One of the original purposes of night vision was primarily to locate all enemy target in the dark. In fact, they are still used by the military extensively for that exact purpose. It is also used for surveillance, navigation, and targeting.

Security personnel often use image enhancement technology and thermal imaging technology for surveillance. On the other hand, hunters only tend to use thermal imaging devices when they maneuver through the woods at night.

Private investigators and detectives also use night vision devices to keep track of the people who are assigned to them. Several businesses use permanently mounted night vision cameras to monitor their surroundings.

One of the most interesting abilities of thermal imaging is that it can reveal whether an area has any disturbance. It will show whether the ground has been recently dug to bury an object, even those that may not be visible to the naked eye. The law enforcement is known to use this to discover items that are hidden by criminals.

Final Words

And, there you have it! We hope this article answers your question regarding what is night vision and how it works. The whole concept behind its functioning is very simple and easy to understand. For years, these handy night vision devices have proven to be extremely beneficial in countless fields, and they will continue to do so in the years to come.

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