Night Vision Devices are green with the purpose of maximizing the received light from natural sources such as starlight or moonlight while in the meantime amplifying those lights with the night vision device so that the user can get as clear of an image as possible. Since, human eye can differentiate more shades of green than any other color which allows for much greater detection of objects
There are three main types of night vision technology – the first type is thermal imaging that detects temperature.
The second type is an active-illumination technology based on infrared lights.
Third one is an image intensification technology or also called a low-light technology.
Night Vision Goggles for instance cannot work in complete and utter darkness since in this case there won’t be any light to be amplified and will rather illuminate it to a level at which the human eye can barely detect. Scientifically looked at the photons hit the lens at the front of the night vision goggles while still carrying the light of all colors, but when turned into electrons they don’t perceive information and the incoming colors and just turned into black and white. But does all of this information answer the question why night vision is green? Barely. Keep reading if you want to dig deeper into that question while looking at things from different angles.
So a big reason why night vision goggles are green is because the screen that is used for image-intensification inside the device itself is mainly made out of phosphor. This substance is used because of its great luminance properties and when struck by the mentioned electrons (which don’t carry color information themselves) they are converted into a bright green glow. The reasoning behind using green phosphor is because the human eyesight is the most sensitive to the green color specter. That can be seen at the
chromaticity diagram below. Based on the diagram below is clear that GREEN is the most prominent.
The human eye can differentiate more shades of green than any other color which allows for much greater detection of objects when looking through the night vision goggles.
Another reason why the color green is present in night vision goggles is because of tactical and technical advantages. For the best reaction time and detection range, the color with the lowest intensity (green) is the best compromise. However, when low-light image displays are not needed, then white or false-colored night vision is more common than the usual green one.
However, when low-light image displays are not needed, then white or false-colored night vision is more common than the usual green one.
But How Do The Green Night Vision Technology Work Exactly?
The night vision goggles are met in many different forms – heat-sensoring, camera based etc.,.. however, the most common and popular technology used for night vision goggles is in fact the image-intensifier tube mentioned which is the most dominant technology to this day when talking about night vision goggles.
The image intensifier technology met in the night vision goggles still needs light to be able to operate normally, but can still manage to pull a decent picture off with very low-level light sources like star and moon lights which can also be called ‘’airglow’’.
To explain how the light can be a factor – A full moon is about 1 ‘’lux’’. A part moon around 0.1 lux and even down to 0.01 while a starlight is 0.001 lux – which means pretty dark in comparison to a full moon. With that into consideration. A tube-based night vision goggle can see even the littles amount of light. Even recent researches have shown that as low as 0.00007 lux can be detected with the green night vision goggles – much further from what our ungeared eyes are capable of seeing.
Light is focused by a lens – similar technology to a simple camera on a photocathode. A photocathode resembles a solar panel – it basically converts light into electricity, with the exception that it never comes out through wires. Instead, the electrons that the light causes are drawn by a vacuum with a very-high voltage electric field and accelerated across this vacuum, gaining energy.
Finally, after this process, the electrons are even further accelerated before hitting the phosphor in the green night vision goggles, where they are converted back into light. Basically the whole process is like a non-stop circulation of electrons. Because this process helps with amplification of the picture when looking through the goggles, the outputted brightness is much higher than the inputted brightness.
Well how much to be precise? – Around 70,000 times brighter for recent technology-based green night vision goggles. Even with some possible losses when passing through the lenses, the image will still appear at least 7000 times brighter to the user through the night versus looking at in with a naked eye.
History for the green night vision goggles
The green night vision device goes way back to World War II, when Germany developed a very primitive infrared device. This technology amplified existing dim light to about 1,000 times, but were huge, bulky and had to be mounted on flatbed trucks, making the truck itself a driving target. Throughout the 1940’s and 1950’s the Army worked with the RCA (Radio Corporation of America) and had a plan to further develop this technology.
By the mid 1960’s, scientists had implemented the use of phosphor into the already bulky and primitive technology, greatly increasing picture quality, from where the famous green color of the night vision goggles came today.
As technology improved with time, shortly after the war the night vision technology was upgraded to a much smaller, less bulky device with an even better resolution. This reliable instrument was also called the ‘’ Generation 2’’.
The USA military continued to further develop this warfare tool as they saw great potential in it and a huge warfare advantage. By the 1970’s there were already developed fitting green-technology weapon sights with night vision targeting and even green night vision goggles that pilots could use. The mentioned 1970’s were also a breakthrough for the thermal imaging, which has also greatly improved in the next several decades. Not later, the ‘’ Generation 3’’ of the green night vision device was developed in the late 1980’s.
This new night vision tool used gallium arsenide for its photo cathode material inside the image intensifier tube which led to producing much better resolution in extremely low light environments. Later on with the technology development this substance was replaced with the phosphor.
The green night vision goggle technology played a crucial role in the Operation Desert Storm in the early 1990’s with one general testimony that the Army’s night vision capabilities where the biggest and only advantage they had.
Today, night vision devices can amplify lights by up to 70,000 times and increasing as the technology is being improved every single year while scientists continue to innovate.
The four-eyed green night vision weapon
Talking about green night vision goggles – exactly the same goggles where used by the Seal Team Six when infiltrating the front door of Al Qaeda’s most wanted leader back in 2011 – Osama Bin Laden himself. You have to make sure they weren’t taking their time looking for a light switch. All they needed was the green night vision goggles that we are talking about in front of their faces. The same simple device every average person can buy which relies on image intensification while gathering the low-level light sources was used to take down one of the most dangerous people on the planet for that time. Green is the color of choice for night vision goggles not only for people that are looking to take a hiking trip through the night but by top-class Navy Seal Team Six – while both the average person and the army relying on the same simple technology – the green night vision goggles. Crazy if you think about it isn’t it?
Do night vision goggles work in total darkness? Night vision goggles fully rely on an image-enhancing technology that has the ability to collect any and all available light – even as minimal as it is and amplifying it greatly so that the user of the goggles can see what is going on when its pitch black. The other technology used in total darkness are the thermal night vision goggles which rely on detecting heat thermal sources at a great distance. The main answer to the question although is that both technologies of the goggles can and will work in complete and total darkness.
Can night vision goggles blind you? – Shortly answered, no they cannot. They cannot damage the eyes in any way and this is another (although not significant) reason why the color of the goggles is green – because it is the less intensified color for the human eye and is not as tiring as other colors of the specter.