The first thing you probably think of when you see the words night vision is a spy or action movie you’ve seen, in which someone straps on a pair of night-vision goggles to find someone else in a dark building on a moonless night. And you may have wondered “Do those things really work? Can you actually see in the dark?”
The answer is most definitely yes. With the proper night-vision equipment, you can see a person standing over 200 yards (183 m) away on a moonless, cloudy night! Night vision can work in two very different ways, depending on the technology used.
If you want to fight wars at night or watch wildlife in the twilight, night vision goggles are the way to go—but how exactly do these clever bits of kit turn darkness into light? Let’s take a closer look!
How to invent night vision:
Imagine your job is to invent a pair of eyeglasses that will help people see at night. It’s obvious what you have to do. Light rays will travel into the glasses at the front, so you must capture them somehow, boost them in strength, and then fire them into the person’s eyes. But how can you capture and boost light?
Binoculars telescopes, and even ordinary eyeglasses will bring light to a focus, but they don’t make it any brighter. It’s easy to invent a pair of glasses that make things dimmer: you just coat the lenses with something that absorbs some of the light—and that’s how sunglasses work. But glasses that make things brighter are a tall order.
So here’s a way to invent goggles that boost light. What if we turn the light into electricity, boost the electricity, and then turn the boosted electricity back into light? That should make the light much brighter so we can see even at night. This unlikely sounding trick really does work—and it’s how night vision goggles help us to see.
Image enhancement – This works by collecting the tiny amounts of light, including the lower portion of the infrared light spectrum, that are present but may be imperceptible to our eyes, and amplifying it to the point that we can easily observe the image.
Thermal imaging – This technology operates by capturing the upper portion of the infrared light spectrum, which is emitted as heat by objects instead of simply reflected as light. Hotter objects, such as warm bodies, emit more of this light than cooler objects like trees or buildings.
In this article, you will learn about the two major night-vision technologies. We’ll also discuss the various types of night-vision equipment and applications. But first, let’s talk about infrared light.
Near-infrared (near-IR) – Closest to visible light, near-IR has wavelengths that range from 0.7 to 1.3 microns, or 700 billionths to 1,300 billionths of a meter.
Mid-infrared (mid-IR) – Mid-IR has wavelengths ranging from 1.3 to 3 microns. Both near-IR and mid-IR are used by a variety of electronic devices, including remote controls.
Thermal-infrared (thermal-IR) – Occupying the largest part of the infrared spectrum, thermal-IR has wavelengths ranging from 3 microns to over 30 microns.
How does a thermal image sensor work?
Rescue workers and firefighters don’t always have free hands to carry things, so not all thermal imaging cameras are handheld. Here’s a handy helmet-mounted camera designed especially for those sorts of extreme situations. I’ve colored most of the main components to make it slightly easier to follow. The infrared camera unit (gray) mounted on the cap of the helmet (yellow) captures a thermal image, which circuits inside (green) decode, amplify, and convert into a form that can drive a traditional display (red).
Here’s how thermal imaging works:
A special lens focuses the infrared light emitted by all of the objects in view.
The focused light is scanned by a phased array of infrared-detector elements. The detector elements create a very detailed temperature pattern called a thermogram. It only takes about one-thirtieth of a second for the detector array to obtain the temperature information to make the thermogram. This information is obtained from several thousand points in the field of view of the detector array.
The thermogram created by the detector elements is translated into electric impulses.
The impulses are sent to a signal-processing unit, a circuit board with a dedicated chip that translates the information from the elements into data for the display.
The signal-processing unit sends the information to the display, where it appears as various colors depending on the intensity of the infrared emission. The combination of all the impulses from all of the elements creates the image.
Other types of thermal imaging cameras use different colors to indicate objects of different temperature—and they’re commonly used to show things like the heat loss from badly insulated buildings.
Scopes – Normally handheld or mounted on a weapon, scopes are monocular (one eye-piece). Since scopes are handheld, not worn like goggles, they are good for when you want to get a better look at a specific object and then return to normal viewing conditions.
Goggles – While goggles can be handheld, they are most often worn on the head. Goggles are binocular (two eye-pieces) and may have a single lens or stereo lens, depending on the model. Goggles are excellent for constant viewing, such as moving around in a dark building.
Detectives and private investigators use night vision to watch people they are assigned to track. Many businesses have permanently-mounted cameras equipped with night vision to monitor the surroundings.
A really amazing ability of thermal imaging is that it reveals whether an area has been disturbed — it can show that the ground has been dug up to bury something, even if there is no obvious sign to the naked eye. Law enforcement has used this to discover items that have been hidden by criminals, including money, drugs and bodies. Also, recent changes to areas such as walls can be seen using thermal imaging, which has provided important clues in several cases.
–Many people are beginning to discover the unique world that can be found after darkness falls. If you’re out camping or hunting a lot, chances are that night-vision devices can be useful to you — just be sure to get the right type for your needs.
Hope This Helps!
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Information Brought To You By Biovolt Corporation.