To see in the dark, all the optical devices that might be helpful for this purpose need to have a source of light present. They are what specialists call light or image intensifiers, and they cannot present you with an image of your surroundings in conditions of absolute darkness. Of course, such a thing would be difficult to achieve, so, for the most part, night vision goggles and other similar devices can do a pretty good job of helping you see in the dark.
However, since such devices use the exterior light to enhance the image in front of the people handling them, there was another problem to address. Strong light sources, suddenly appearing in the field of view, could create such conditions that users of night vision devices risked temporary blindness.
How have night vision devices evolved?
Since the point of using a night vision item could become null if a simple flashlight was pointed at the person using it, specialists in the field thought about creating devices that were not as susceptible to dangers such as the one mentioned just earlier.
For this particular reason, something called a light limiter was invented. Today, all the modern equipment used for night vision comes with such light limiters. The role of this feature, as you may well suspect, is to make sure that light sources that are strong enough to mess up with the intensifying light feature of your gear will no longer interfere.
But how does such a unit work? You may wonder. The point of using night vision is to detect the light radiation that is undetectable for the naked eye. Making use of infrared and ultraviolet radiation, the night vision devices that are currently available, for military and civilian use, ensure that the spectrum for detecting light is enlarged and enhanced.
At the same time, the technology used makes sure that what light sources are too intense don’t hurt the users’ eyes, which is the primary role of the limiters we talked about.
Understanding the main night vision options
Without having to become an expert in optics, you might like to learn a few things about the main options used today for night vision. While the goggles used by military experts and seasoned hunters might use image intensifiers, other devices, such as night vision binoculars, might come with active illumination features, too. We will explain both types right away, as that will serve as an excellent introduction to the kinds of light that play a role in how night vision works.
What are image intensifiers?
Image intensifiers are devices using a type of technology that focuses on artificially increasing (amplifying) the number of photons emitted by the sources of light surrounding us. Be it that you want to hunt under the light of the moon and the stars, these celestial bodies will produce enough illumination that can be gathered by your night vision device and enhanced.
In other words, the light received through the lenses is multiplied, resulting in an image that you can see. The devices that use this type of image enhancement are called NVDs, which is short for night-vision devices. By enhancing the visible light, as well as the infrared light that is not visible with the naked eye, these units are capable of providing you with the ability to see in the dark.
You can find some highly sophisticated devices, and they can be used in a broad array of applications. You might not necessarily see a cheap night vision monocular that can provide outstanding results, but there are products even intended for civilian applications that can offer such outstanding performance.
How is the active illumination used?
The other popular option that you have at your disposal is active illumination. This kind of technology uses the image intensification technology, but it also adds a source of light. The said source of light is infrared, and its central role is to add more light to the surroundings so that the results are enhanced.
Shortwave infrared light can be used by more advanced devices, for the simple reason that the shorter the waves, the more light energy they give. Wavelength is an exciting aspect we should talk about. From the visible light spectrum, violet comes with the shortest wavelength, and therefore, it provides the most energy. For this reason, the violet light gives the most radiation.
However, violet is part of the visible light spectrum, as mentioned, and that is why you need to take advantage of the infrared light, which is part of the invisible (to the naked eye) light spectrum.
What are the types of light used by night vision technology?
Now that you know more about the night vision technology and its types, let’s make everything clear regarding the light used for making it possible. The infrared spectrum comes in three forms, as follows:
– Near-infrared – the wavelength for this type of light is between 0.7 and 1.3 microns; it is at the border with visible light.
– Mid-infrared – the wavelengths for this type of light is between 1.3 and 3 microns; many electronic devices that are readily available use this type of light.
– Thermal-infrared – it takes most of the infrared spectrum; its wavelength varies between 3 to more than 30 microns.
Why are these light types important?
Night vision would not be possible without a source of light. Visible light, as is the one given by the surroundings, celestial bodies, and not only, is harnessed by night vision equipment to create that image you can see through your lenses. The other type of light used belongs to the light spectrum that is not visible with the naked eye, and it is called infrared.
You can use night vision today for a wide variety of applications. For surveillance, hunting, and many other purposes, it can prove a valuable tool. Learning about it can also help you understand how it works, and expand your general knowledge on products you use.