How Thermal Vision Works
You’ve probably heard the term “thermal vision” kicked around when looking at night vision gear. If you’ve nodded sagely and then Googled it when you got home, here’s the rundown on what the technology does – and what it can mean for your next mission.
Giving Your Eyes a Little Boost
Many night vision devices work like you own eyes – they use the amount of light available to help you see. Unlike your own eyes, though, night vision gear also makes use of the small amounts of light in the low end of the infrared light spectrum, which enhances your vision. Not quite to cat-like levels, but enough so that you can see targets in the dark.
While night vision scopes and goggles can magnify even small amounts of light, that’s not usually enough to get the real results. For that, you need good vision contrast. When your target has good visual contrast and is brighter than the background, they’re going to be easier to see. It becomes mission critical to get this contrast if the target is trying to blend into the background, is wearing camo or dark colors, or is moving in a dense forest.
Going Beyond Vision
Here’s the cool part: vision enhancement technology in night vision scopes and goggles lets you see light while thermal vision in essence lets you “see” heat. Thermal vision technology captures the lower end of the light spectrum. This end of the infrared light spectrum is emitted as heat. Luckily, warm bodies such as animals and people emit more of the light than trees or other inanimate objects, so people and animals stand out with thermal visioning very clearly.
And it gets better; hotter objects create more thermal contrast, so a larger animal (including a larger human animal) on the run becomes very easy to spot. It if they are wearing a disguise, their own body heat gives them away. One caveat: targets can potentially thwart thermal vision by swathing themselves in metallic fabric that is similar to the kind of fabric firefighters use. Let’s hope your targets haven’t been buying Adam Harvey Stealth Wear fashions.
It’s not just living, breathing things that can be seen with thermal vision, either. Everything gives off some thermal energy. This means that with thermal vision gear anything that’s hot will show up, something the military can take advantage of when searching for fires or hot car engines at night.
There’s another big advantage to thermal vision: in lousy conditions such as fog, rain, or smoke, regular light enhancing night gear isn’t as effective because all of these conditions can reflect light. Thermal vision, on the other hand, still gets you that contrast you need to make your target stick out. Thermal vision technology also beats out other night vision gear in very low-light conditions and in conditions where too much light occurs (think headlights from cars or streetlights).
How Your Thermal Vision Gear Works
Thermal vision gear works by using a special lens to focus infrared light that is being emitted by the objects being viewed through the device. In about one-thirtieth of a second, infrared-detector elements scan the light being emitted and generate a thermogram which is then translated into electric impulses which can be sent on their merry way to a circuit board with a dedicated chip so that the information can be translated and sent on to the display. At that point, you can check out the image that crops up on the display. The whole thing takes place in a fraction of a second.
While using thermal vision technology may seem very high-tech and new, it is in fact as old as dirt – or at least as old as snakes. Rattlesnakes catch their prey because they can see light in the thermal infrared spectrum, letting them see lunch (or at least the body heat that lunch produces).
Okay, knowing about infrared light may not make you more accurate, but for important missions where you may have to deal with targets trying to disguise themselves or may need to deal with conditions that make your regular night vision scope less than useful, thermal vision can make a big difference.