Last Updated on March 9, 2021
No doubt, night vision is an awesome technology that has changed the idea of viewing in the dark. Most people are familiar with this concept & people who haven’t heard about it, must have seen it in action movies, at least. So, what is night vision technology, and how does night vision work?
As a night shooter, hunter, wildlife observer, even technology enthusiast these questions must have popped in your mind every now and then, we bet! If that is the case, then guess what? You are in the right place to about night vision in-details!
Before, people were unable to see what was in the dark and struggled to have a clear vision in the low light situation. But night vision made this task easy. So, let’s dive into the working principle of night vision to have a clear understanding of this topic. Afterward, we will cover other important things.
What is Night Vision?
Before unfolding the working process of night vision, let’s discuss what is night vision, first.
After the sun is set, people really struggle to see any object clearly if there is no alternative light source. In the dim light situation, people can’t have a clear understanding of what is really out there and in the dark light, they simply can’t see.
Night vision technology solves all these problems of night vision for you and enhances the power of capturing everything out there in the low light as well as in the dark. Through this marvelous system, you are now able to be your own version of James Bond! So, how does night vision technology work?
How Does Night Vision Work?
Night vision technology works mainly in three different ways. The first way is the image enhancement process, the second way is active illumination and the third way is thermal imaging.
In the below sections we will discuss these processes in detail. Before that, we need to have a basic understanding of light and how it works.
How Light Helps in Vision
Humans can see better in the daytime and that’s why we work in the day and sleep at night. We have a retina in our eyes that is light sensitive. This retina has two major cells namely rods and cones. Rods are experts at detecting movement in the dim light situation and cones are experts at seeing the colored light spectrum. In number we have rods 20 times more than the cones and, yet we are not able to see well in the dark!
Just after the visible red light spectrum is the infrared light.
Infrared (IR) Light
Infrared light has three separate categories.
This is the closest to the visible light wavelength. Its wavelength ranges from 0.7 microns to 1.3 microns.
This wavelength ranges from 1.3 microns to 3 microns. These two IR categories are vastly used for remote controls and other electronic equipment.
Thermal infrared is the longest part of infrared which ranges from 3 microns to 30 microns.
But, there is a key difference between the thermal IR and the other two IR. The thermal infrared light is emitted by an object whereas others are normally reflected off the objects. This happens because of the phenomena that occur at the atomic level.
Let’s know why this happens.
Atoms are generally in motion all the time. Even in solid objects! They vibrate, rotate, and move constantly. This excitation level can vary according to the amount of energy it gets. If we can provide a certain amount of energy to an atom, which is called the ground state energy level, it will move to another excitation level.
To what level the atom will jump on, depends on the amount of energy applied to it through heat, light, or electricity. We can also think of this incident from an electronic perspective.
As we know that atoms consist of electrons, protons, and neutrons. Neutron and proton consist of a nucleus. Electrons are orbiting the nucleus having different energy levels according to the orbit, the more distant the orbit from the nucleus the more energized the electrons from that orbit are.
When electrons are energized to a certain level, they move to the upper level. But, they also want to return to the original level, and whilst doing it, they release the extra energy as a particle of light called the photon. What we see is the atoms releasing photons as energy. In the night vision equipment, the thermal imaging system works through this infrared emission of light.
The first method that night vision devices use to generate images at night is image enhancement or image intensification. But, what is an image enhancement, and how does this technology work actually?
Most of the night vision equipment uses image enhancement technology. When you are talking about night vision, most people think that you are talking about image enhancement. Also, this image enhancement system is called NVDs.
Let’s know how night vision works for the image enhancement method.
At first, the objective lens captures the ambient light as well as some near-infrared light from natural sources. This objective lens is not a very complex level lens rather a very conventional one.
Next, the light captured is sent to an image intensifier tube. Then the tube gives an output of around 5000 volts which is very high to the components of the image tube.
Converting into Electrons
This image intensifier tube then converts the light into electrons through its amazing component named photo-cathode.
When the electrons are passing through the tube, similar types of electrons get released into the tube from the atom. So, the number of electrons is multiplied by a factor of thousands and that is done by a component named microchannel plate (MCP).
Multiplying the Electrons
Each of the channels has a length of about 45 times its width. The sole purpose of this channel is to multiply the electrons. The whole process begins when the electrons from the photocathode are hitting the MCP on its first electrode. Then it is transferred into the glass channels by the thrust of 5000 volts and is sent between the pair of electrodes.
As a result, there are millions of new electrons along with the original ones by this cascaded secondary emission. Most amazing is that the MCP channel is designed in an angled way, from 5 degrees to 8 degrees, so that the electrons can easily collide with the channel body. It also helps to reduce the feedback of the ion and direct light on the output side that comes from the phosphors.
In the last part of the image intensifier tube, there is a screen coated with phosphors on which the electrons hit. While passing through the channel, the electrons maintain their position in relation to each other which helps to provide a perfect image of the object. This happens because the alignment of the electrons is kept the same through its travel.
The phosphors then release photons because the energy of the electrons forces them to do. Then the green image is created on the screen of the night vision because of the phosphors.
There is also another lens called the ocular lens that helps to see the image. It also helps the viewer to magnify the image and focus on it. There may be a monitor to display the image or it can be viewed through the ocular lens directly. The output image is called intensified as this is brighter than the incoming light.
This process is called image intensifier as it collects the tiny bit of light available in the surrounding darkness and boosts perfectly for our eyes. But you won’t find light all the time you are using night vision.
So, what happens when you are in full darkness? The image enhancement technology doesn’t work if there is no light at all. In this situation, you need thermal imaging.
- Low power consumption
- Works great in the low light situation
- Don’t work in fully dark situations
- Bright light sources can damage NVDs
Active illumination combines an active source of illumination with image intensification technology. The process works in the near-infrared or shortwave IR band which spectral range is 700 to 1000 nm. So, have a look at how active illumination technology works.
Active illumination night vision converts light photons into electrons. After that, the electrons are converted and amplified as visible light through some chemical and electrical processes.
This technology can incorporate illuminators for higher levels of IR light resulting in high-resolution images than other technologies. The scenes, which are apparently dark to the human observer, are displayed as a monochrome image on the normal display.
Nowadays, many low light cameras use this technology for residential, commercial, and government security purposes. Several goggles also incorporate this technology. Laser range-gated imaging devices also utilize this technology with a high power source that provides better illumination and imaging minimizing the effects of fog, smoke, rain, or mist.
- Works great for target recognition
- Perfect for security purposes
- Long distances military uses of goggles can be risky
In this thermal imaging system, we will look for the heat that the objects give off instead of the light that they reflect. In general, any living thing which is moving at night is going to be hotter than its surroundings. It is also applicable to any vehicles and machines.
Hot objects always give off infrared radiation that is a similar type of energy to light but has a slightly longer wavelength. So, they convert the infrared radiation into a visible image. There are many thermal imaging cameras that use different colors to indicate objects having different temperatures.
Now, we’ll cover how does thermal imaging works.
At first, a special lens focuses the infrared light emitted by all the objects.
Then, a phased array of IR detector element scans the focused light. A temperature pattern is then created by the detector elements which is called a thermogram. It’s a very detailed pattern that is created within one-thirtieth of a second by the detector array. It obtains the temperature information and thus makes the thermogram.
That information is taken from thousands of points from the field of view by the detector array. Next, this thermogram created by the detector is converted into electronic impulses.
After that, these electronic impulses are sent to the signal processing unit which is a circuit board having a dedicated chip. This chip then translates that information into data from the elements and makes it ready to display.
The signal-processing unit immediately sends that information to the display unit where it can be seen in different colors. Those colors will depend on the intensity of the IR emission. The whole image is created by combining all the impulses from all of the elements.
The thermal imaging scopes available in the market can scan at a rate of 30times/second. In general, they can sense temperatures that range from -20 degrees Celsius to 2000 degrees Celsius! They can also detect the temperature change of about 0.2 C.
Thermal Device Types
Typically, there are two types of thermal imaging devices. The first one is the un-cooled one. It is the most common type among the devices. These types work perfectly at regular room temperature. It is completely quiet meaning it does not make any sound during the operating process. It is activated immediately and, also has a built-in battery system.
Thermal imaging is great at detecting objects in a pitch-black situation. Although, most night vision devices use image enhancement technology.
- Perfect for smoky, foggy, or dark situations
- Allows day and night use
- Can’t differentiate between friends and enemies
- Devices are expensive
History of Night Vision Devices
Seeing at dark was a long-cherished desire to humans for thousands of years. Besides, it became urgent mainly for military purposes in the early 20th century. From the need, scientists researched hard and finally developed this wonderful technology.
The main researches began in the 1940s. German army successfully developed NVDs earlier in 1939 and was used in the Second World War The US military established this technology by the late 1940s. The viewing devices came with viable infrared systems in the 1950s that was the active illumination technology.
From the beginning until today’s NV technology passed a long way. By this time, many developments took place and each development is leveled as “Generation”. The prominent NV generations are discussed below to inform you how NVDs have changed over time.
Night Vision Generations
Night vision devices are around for 80 years. There are many different night vision generations. Whenever any new technological advancement was made, a new generation was introduced to the market. So, what are the generations?
The United States Army introduced the first-night vision into World War ll and the Korean War in the 1940s and 1950s. They used the active infrared called IR illuminator. By attaching powerful IR illuminators to the NV devices, they did that. These were basic techniques.
This technology used the anode connected with the S-1 photocathode to accelerate the electrons. However, the images distorted and the life cycle of the tube was not very big. Besides, the advancement of the hostile nation’s weapon was a major setback for the gen 0 devices.
Truly, these devices were the researched phase equipment and now totally obsolete from the market.
- Require invisible IR source
- Based on image conversion
Up next, generation 1 devices used passive infrared instead of active infrared. They used the ambient light of the moon, star and made very good use of it. That’s why this is called “Starlight Scopes” sometimes. These devices developed in the 1960s. Usually, these scopes allow you to view targets 75 yards away in dark.
- Introduced active illuminator
- Based on image intensifier
- Great for short-range shooting
- Affordable than others
After the 1st generation gone, there was a vast improvement in the gen 2 category. The performance and resolution of the new generation improved quite a lot from its previous version. The main development of generation 2 devices took place in the 1970s. Handheld and helmet-mounted devices that we find nowadays, were firstly developed in this time.
- 40 to 72 lp/mm resolution
- Introduce MCP
- Improved resolution
- Versatile application
- 16 to 24 Signal-to-Noise ratio
- 5000+ hours tube life
In the early 1980s, the 3rd generations’ night vision optics came into the market. The US military uses this generation today. It is quite the same as generation 2. However, the resolution and sensitivity are much better. That happened because of the use of gallium arsenide in the photocathode.
This helps to convert the photons into electrons very efficiently. Also, the MCP has a longer life cycle because of the coating with an ion barrier.
- Introduce GaAs photocathode and ion-barrier in MCP
- Resolution from 64 to 72 lp/mm
- 16 to 24 Signal-to-Noise ratio
- 10000 hours tube life
The latest 4th generation night vision optics were developed in the 2000s. The main development field in the 4th generation devices is the removal of the ion barrier. These devices are sometimes called “filmless and gated” optics. That helps to make it less noisy and improved the signal to noise ratio.
Besides, more electrons can reach the amplification stage. As a result, the image quality gets better than all other earlier generations. There is an addition of an automatic-gated power supply system.
When you are having any bargain devices, you can be sure that those are using either gen 0 or gen 1. You will be disappointed when you use those things, as they do not offer much. The modern devices are a bit pricey but they are handy items.
- Superb resolution images
- Eliminate ion-barrier
- Best for tactical purposes
- 64 to 72 lp/mm resolution
- 25 to 30 Signal-to-Noise ratio
- 10000+ hours tube life
Night Vision Equipment
There is quite a lot of equipment that people use for night vision. The most important categories are:
Night Vision Scopes
These are very popular among shooters and hunters. They are monocular items. They can mount on the rifles and can help you for taking the game at night. The night vision scopes are really great to have when you are taking outdoor journeys and military operations.
Night Vision Goggles
These items are normally handheld. There are two types of them monoculars and binoculars. They are very good for constant viewing of the night. You’ll also find quality goggles for night vision on the market like the scope.
Night Vision Cameras
Cameras can send the night vision image to a monitor or VCR. People use them in buildings for security purposes. Some of them are also used as outdoor trail cameras. The newest camcorders have built-in night vision technology with them. In-depth knowledge can be acquired by being members of different forums about night vision found online.
These are the major night vision device categories. There are also a few more types that ease our life to a great extent.
Applications of Night Vision Devices
Night vision devices have unbounded uses in various aspects. Although NV technology was originally developed for military purposes. However, it is now acting for usual night observation tasks also. The major applications are listed below.
- Military and Law Enforcement
- Security and Surveillance
- Search and Rescue
- Nature Viewing
- Cave Exploring
Why is Night Vision Green?
You may sometimes wonder that “why is night vision green”. Well, the photons carry all the colors at night when they are absorbed at night. However, when the components of the devices convert these photons into electrons, they lose their original color and only black and white are left. As our eyes can have a long look without any discomfort to green light, the phosphors help the black and white image to present before us as green. That is why it looks green.
Thermal Imaging vs Night Vision vs Flashlight
Sometimes newbies get confused and think night vision, flashlight, and thermal vision are developed in the same technology. But it’s totally a wrong conception. The main purpose of these night optics is to view objects clearly at night. However, there are lots of differences. This is why; you should know their dissimilar features.
The flashlight is used for usual viewing purposes that can make targets alert but night vision and thermal devices are designed for viewing objects without alarming them. However, several lights are available that assist hunters and shooters such as coyote hunting light, predator tracking light, or coon hunting light.
Typically, thermal optics are expensive than other twos. And flashlights are the least expensive that offer doing limited tasks.
Popular Night Vision Brands
Night vision optics come with a variety of price tags. You should consider first, where you are going to use your device. If you want to choose the top night vision scopes for military operations then you should go for the higher generations that will increase the prices. But you will find cost-efficient optics that will be quite good for short-range hunting, shooting, or wildlife observation.
The first night vision device was for locating the enemy at night. Still today, these optics are vastly using in law enforcement tasks. Besides, they are playing a significant role in modern life from home security to outdoor and wildlife observation. Moreover, several of them are helpful for you in daytime use too.
Knowing different night vision technologies and how does night vision work will help you greatly to choose the right technology amongst image intensification, active illumination, and thermal imaging for the right situations. Let’s know which technologies you love most.
I hope, you enjoyed the article very much. And don’t forget to share your night shooting experience with us.