Night vision scopes work like magic. In settings where our eyes are useless, these devices come to your rescue. In reality, there is no trick used with a night scope. There is only science. For now, it is better for you to know how does a night vision scope before wondering about anything.
Most of the standard night visions will let you see a person at 200 yards (183 meters) even there is a zero visibility. In this sense, these visual accessories are ideal to be used during the night or areas where there are poor lighting. There are two ways on how a night vision scope works. It just depends on the design and system that were used.
Two Ways A Night Vision Can Work
This is the most common design of today’s night vision scopes. The device collects a small amount of light and amplifies it up to the point it can produce a comprehensible display. Aside from light, image enhancement scopes also gather some portions of the infrared light spectrum. Your eyes may not see these elements, but they are just there. These factors are essential in the processing of visual images amidst the darkness.
By default, thermal imaging is a form of night vision. A thermal imaging device will let you see you see the upper part of the spectrum of infrared light. Specifically, this element is emitted as a form of heat instead of light. Of course, hot objects like human bodies are emitting more of this light than cold objects such as trees.
A Little Science Of Light
Before you can fully understand night vision scopes, you should know more about the concept of light. Light have specific wavelengths. These are the energy that a light can produce. You can expect that lights that produce shorter wavelengths have higher energy levels. When it comes to visible light, the color violet has the highest energy. On the other hand, the red is the weakest.
After the visible light comes the infrared spectrum. There are three categories in where you can categorize an infrared light. Here are they:
- Near-Infrared – You can say that this light is close to being visible to the naked eye. A near-IR has a wavelength that spans between 0.7 to 1.3 microns
- Mid-Infrared – This infrared light has a wavelength that ranges from 1.3 to 3 microns. Today, near-IR and mid-IR has a variety of applications, aside from being in a night vision scope. Such of these are remote controls of your television.
- Thermal-Infrared – This one occupies the biggest portion of the infrared spectrum. Specifically, its wavelengths range from 3 microns to more than 30 microns.
The main difference of thermal infrared to the other two is that it is emitted by the object, instead of being reflected off it. This technology is common in thermal infrared scopes.
How Does A Night Vision Scope Work
As mentioned, image enhancement is the common type of night vision scope. This technology heavily relies on image intensifier tubes in collecting and amplifying both visible and infrared lights!
Here is how this technology works:
- A night vision scope contains an objective lens. This is the component that captures the surrounding visible and near-infrared lights.
- After collecting, the gathered light is passed through an image-intensifier tube. Most of the night vision devices (NVD) today power their image-intensifier tubes by the use of double-A batteries. This tube gives off a high voltage to its components, specifically around 5,000 volts.
- The image-intensifier tube uses a photocathode. This component efficiently converts the photons of light into electrons.
- The converted electrons are then released from the tube. But this time, the number of electrons has been multiplied already. Usually, the multiplication is by a factor of thousands. Before we forget, it is the micro channel plate (MCP) of the tube that multiplies the electrons.The MCP is similar to small glass disc. This disc contains millions of microscopic holes from a fiber optic technology. Going back, the MCP is installed in a vacuum and comes with metal electrodes of both of its side. Every channel functions as an electron multiplier. This is the reason why the tube can amplify the number of electrons that are passing through it.After passing through the photocathode, the electrons then hit the first electrode layer of the MCP. Once this happens, the electrode accelerates the electrons into the glass micro channels, using a series of 5,000-volt bursts. After this, the electrons will release a thousand more copies of them on each channel. This process is called the cascaded secondary emission.This process is quite repetitive. Therefore, it causes a proliferation of electrons even though there are only few that entered. It is the chain reaction that causes the amplification of visuals. However, this is still not the end of the process.
- The end of the image-intensifier tube has a screen coated with phosphors. This is where the multiplied electrons gather and rearrange themselves depending on the channel they entered. This enables the perfect arrangement of the image. By concept, the electrons stay in the same position as their original photon source.On the other hand, the energy coming from the electrons triggers the phosphors to be excited. As a result, the screen releases the electrons in the form of photons once again. Specifically, it is the phosphors that create the green images you can see on your night vision scope.
- The green images pass through another lens called the ocular lens. The ocular lens is the one that enables you to focus and magnify the entire image.
One of the things that you should appreciate about image-intensifiers tube is that they undergo military testing. This is to ensure that their performance and quality meet the industry’s standard. Those tubes that passed are called as MILSPEC, while those that didn’t are categorized as COMSPEC.
Knowing how does a night vision scope works will make you realize how sensitive this device is. Therefore, it is appropriate to care of this accessory properly. Moreover, you may want to choose the best night vision scopes to ensure their durability and reliability. After all, these things are not cheap at all!