How Does Night Vision Work? Tech + History Explained

So how does night vision work, and what is the history behind the technology? Let’s jump in.

Night vision scopes, goggles, and other devices intensify low ambient light and near-field infrared energy (from IR illuminators, for example) to illuminate the user’s surroundings during times of low light or in complete darkness at night.

First, the objective lens at the front of the device captures light (photons) which then pass to an image intensifier tube. Batteries power the first part of the tube, the photocathode. All this activity takes place in a vacuum.

The powered photocathode triggers a photoelectric process that actively converts photons into electrons, which are then passed to the next part of the tube known as the microchannel plate.

The MCP — Where Electrons Multiply 

The microchannel plate (MCP) consists of millions of microscopic channels where electrons multiply. Electrons are forced into the MCP and collide with the atoms inside the walls and channels, thus generating additional electrons.

Once you only had a few electrons, you suddenly have hundreds of thousands more. When these electrons exit the MCP, they hit the phosphor screen in the same patterns as when they first entered as protons — thus creating a perfect replica image.

Why are NV Images Green (or White)?

NV images will look green or white, depending on the phosphor screen color used.

That green color is generally what you imagine when you think of night vision, but manufacturers now offer white phosphor, which many hunters prefer because it provides greater contrast and depth.

Ultimately, NV scopes must have light to work, no matter how dim. That’s why hunters need moonlight, starlight, or an IR illuminator in the pitch black for their night vision scope to spot varmints.

This reliance on light makes night vision technology fundamentally different from thermal devices.

Night Vision vs. Thermal Technology

Thermal devices don’t need light to produce an image. Instead, thermal scopes and monoculars capture infrared heat through an objective lens made of germanium.

Companies use germanium because, unlike glass, it allows infrared heat to pass through the lens — which is critical if you plan to use an NVD to look through a car or kitchen window.

So, if you plan on scouting from your truck, be sure to roll the window down. But, let’s get back to how these things work.

When the infrared heat enters a microbolometer, it’s translated into heat information on a thermogram. That thermogram converts the info into electrical impulses that are then processed and sent to an AMOLED or LCD for viewing.

Depending on the number of pixels in the microbolometer and the display screen’s resolution, the image might appear either sharp and detailed, or like an orange blob.

That leads us to the basic Pros and Cons, the issues that should guide your purchase decision:

Benefits & Drawbacks of Thermal Imagers

A benefit of thermal devices is that they work in fog, haze, smoke, and blackout situations — because they don’t rely on ambient light. So, when conditions get tough you can rely on a thermal more than a NVD.

In the context of hunting, users complain that thermal scopes don’t provide the visual depth that traditional NVD scopes do.

Bottom line: While thermal devices deliver excellent animal detection while hunting, night vision provides more detail to better identify animals and get a feel for the depth of a scene.

Now, let’s consider how each system works.

How People “See” with Traditional Night Vision

Crucially, images seen through NV tubes are not filtered through electronic components and sent to a two-dimensional screen for viewing.

There are no screen refresh rates or signals to decode and make visible. Instead, NV scopes amplify the scene and show it to you as it is, with no digital processing required.

For hunters who must have the best tools available to identify animals before shooting, I think many would tell you night vision is the way to go. But it’s limited because hunters can damage the image intensifier tube by using it in situations where lights could flash brightly — assuming the device doesn’t have auto-gating.

I’d recommend grabbing a thermal monocular for detecting animals and a NV scope for identification and shooting purposes — that way, you get the best of both worlds.

And for roughly the price of one high-end unit — thermal or night vision — you can get both device types, each of somewhat lower quality. When it comes to night vision, two kinds of eyes are always better than one.

Night Vision vs. Digital

Digital night vision devices are the new kids on the block. Like traditional NV devices, they rely on light to produce images. Think of digital night scopes as digital cameras that have been tuned to work in the dark.

Indeed, they use the same technology as digital cameras. It goes like this: Light enters the objective lens and hits a complementary metal-oxide semiconductor (CMOS) sensor.

The CMOS sensor turns the light into a digital signal. Once digitized, the signal gets sent to a screen where the hunter can see it. Like digital cameras, the bigger the CMOS sensor, the clearer the images.

By using a CMOS sensor coupled with wi-fi and multi-core CPUs, digital night vision scopes come with bells and whistles that are impossible with analog NV scopes.

These digital devices can record video, integrate with your mobile phone, and provide higher magnifications than most traditional night vision rifle scopes. Just know this: You’ll burn through batteries quickly with all this tech. So if you go the digital route, bring extra batteries.

If you want to pair your rifle with one of the coolest, most intelligent scopes on the market, Pulsar has just the ticket — the Digex 50.

The History of Night Vision Devices

Wondering when night vision got its start and how it has progressed through recent history? Here’s a brief history lesson on how NV tech, the context it’s been used, and how it has advanced over the last century.

Gen 0

First used by the Germans on their WWII tanks, these early night vision devices used a critical piece of technology known as a photocathode.

The photocathode is the building block of night vision image intensifier tubes (IITs). It enables NV scopes to turn photons into electrons, the key step in making the technology work.

Gen 1

Used by Americans in the Vietnam War, these bulky units improved photocathode technology by boosting the photons-to-electrons process.

More electrons mean more visible light on the phosphor screen, thus making dark nighttime scenes easier to decipher; check out the next section titled “How Does Night Vision Work?”

Gen 2

In the late 1970s, microchannel plate (MCP) technology took NV to the next level by acting as a breeding ground for electrons.

When electrons are forced into the MCP’s millions of microscopic channels, they smash into the walls and atoms inside the plate, creating even more electrons in what’s called a secondary emission. And more electrons mean much better image quality.

Gen 2+

Gen 2+ builds on Gen 2 by using better tubes, higher resolutions, and improved optics. It isn’t a formally recognized standard — it’s primarily a way for companies to differentiate their products — but it is a significant advance over early Gen 2 scopes.

Gen 3

In Gen 3, Gen 2 photocathodes are replaced by gallium arsenide sensors that capture many more photons than previously possible.

Plus, MCPs were coated with an ionized film that prolongs the life of the device by blocking free ions from entering the tube.

But early iterations of the film reduced the inherent gains of gallium arsenide MCPs, so later Gen 3 tubes compensated by switching to filmless or thin-film designs.

Auto-gating was a major Gen 3 breakthrough because it enabled the photocathode to turn on and off rapidly, to prolong the lifespan of a device. Previously, too much light from, say, a muzzle blast could burn out the image intensifier tube.

Plus, auto-gating helped keep the image evenly lit, no matter how drastic the changes in light levels. Auto-gating quickly became a must-have feature for surveillance because light levels in urban environments are rarely static.

Gen 4

All NV companies would have you believe they’ve got Gen 4 devices — but the US Army wouldn’t classify them as such. Products marketed as Gen 4 are typically a Gen 3 tube with auto-gating and a filmless MCP that transfers more electrons.

Night Vision is an Ever-Evolving Technology

Thanks for checking out our post explaining how exactly does night vision technology works. The answer may not be easy to grasp at first, but we did our best to break it down into understandable terms for you. It’s best to wrap your mind around the technology before dropping big money on a scope or monocular.

If you have any feedback or questions, please reach out to us by leaving a comment below or contacting us directly.