How Do Different Types of Night Vision Goggles Work?

TL;DR

Night vision goggles work in three ways: active illumination emits near-infrared light like a head-mounted flashlight, image intensification amplifies existing light, and thermal imaging detects thermal radiation. Affordable commercial models use active illumination and cost less than $200, while the military relies on passive image intensification (like the PVS-31As) so enemies can't spot an infrared beacon. Discover why active illumination causes motion sickness and can't be used in combat.

Transcript

• What happens when you take the world's best night vision goggles into the world's darkest room? - You start to feel a little strange. And sometimes start to get a little bit of vertigo. - Can you tell the difference between your eyes being closed and open? - Should not be able to. It'll be that dark. - Three
• Basically zero light in here.
• Two.... Read More

Key Insights

• 🌃 Night vision goggles come in different types, each with its own advantages and limitations.
• 🙂 Image intensification goggles, used by the military, rely on existing light and provide a close replication of natural vision.
• 🙂 Affordable night vision goggles often use active illumination, emitting near-infrared light for cost-effectiveness in commercial and security applications.
• 🕵️ Thermal imaging, which detects thermal radiation, is a powerful tool for completely dark environments.
• 🧑‍💼 Night vision technology has evolved over the years, with constant research and improvements aimed at minimizing trade-offs between resolution, delay, portability, and concealment.
• 😷 Night vision technology has applications beyond the military, such as search and rescue, firefighting, and medical imaging.

Questions & Answers

Q: How do night vision goggles work?

Night vision goggles either create their own light, amplify existing light, or image in the emissive infrared bands. The most common consumer version, active illumination, emits near-infrared light (wavelengths just longer than our eyes can see) and uses a camera to capture it and display the scene on a screen. This is essentially like strapping an invisible flashlight to your head.

Q: What are the three types of night vision?

There are three categories: active illumination, which creates its own near-infrared light; image intensification, which amplifies existing light; and thermal imaging, which detects thermal radiation in the emissive infrared bands. Active illumination is the cheapest, while image intensification and thermal can each cost thousands.

Q: How much do active illumination night vision goggles cost?

Active illuminators cost less than $200, making them the simplest and cheapest form of night vision. Because they are far easier to make than other kinds, they are used in almost all commercial night vision goggles and nighttime security cameras. Other types of night vision can cost thousands.

Q: Why can't the military use active illumination goggles?

Active illumination goggles emit a bright beacon of near-infrared light, so enemies can easily spot the wearer. They aren't passive. For this reason the military relies exclusively on image intensification, which amplifies existing light without giving off any beacon, keeping operators concealed.

Q: What are the drawbacks of active illumination night vision?

There is a significant delay between what the camera sees and what appears on screen, limited by the frame rate. At 24 frames per second the delay is about 1/24 of a second, or tens of milliseconds, which is enough to cause motion sickness and loss of coordination. The range is also limited, since you can only see as far as the emitted light reaches.

Q: Do night vision goggles glow or give you away?

Active illumination goggles emit near-infrared light that human eyes cannot see, but they create a bright beacon in the near-infrared. Anyone with military image intensification goggles, which can still see near-infrared, can easily spot someone using an active illumination device.

Q: Do night vision goggles work in total darkness?

It depends on the type. Image intensification amplifies existing light, so it needs at least some photons to work. Thermal imaging, however, detects thermal radiation and needs no external light source, making it useful in pitch-black conditions as well as smoke and fog where other types struggle.

Summary & Key Takeaways

• Night vision goggles work by capturing and amplifying available light or emitting their own near-infrared light to enhance visibility in dark conditions.

• There are three types of night vision: active illumination (using near-infrared light), image intensification (amplifying existing light), and thermal imaging (detecting thermal radiation).

• Military night vision goggles use image intensification without active illumination to maintain stealth, while affordable commercial goggles use active illumination for cost-effectiveness.