What is the difference between active illumination and image intensification night vision?

Active illumination uses a built-in near-infrared light source, making it simple and cheap but detectable. Image intensification amplifies ambient light thousands of times, offering better stealth and no delay, but requires some existing light.

Can you see in complete darkness with night vision goggles?

Image intensification requires at least some ambient light to amplify. For absolute darkness, thermal imaging is the most effective as it detects emitted heat, or active illumination can be used but compromises stealth.

What are the most advanced military night vision goggles?

The GPNVG-18 goggles are among the most advanced, offering a wide field of view using four image intensification tubes and unparalleled resolution, though they come at a very high cost.

Why is the image in night vision sometimes green?

Traditionally, night vision screens used green phosphor because the human eye's low-light sensitive rods are most sensitive to blue-green light, and green provides good contrast. Modern goggles may use white phosphor for better detail.

What is the resolution measurement for night vision?

Night vision resolution is measured in line pairs per millimeter (lp/mm), indicating how many pairs of fine lines can be distinguished within one millimeter, rather than pixels used in digital cameras.

What are the benefits of thermal imaging?

Thermal imaging can see in complete darkness without any external light, through smoke or fog, and can detect heat signatures from a great distance, even revealing objects buried underground or recently touched.

What are the different generations of night vision?

Night vision has evolved through generations: Gen 0 used active IR, Gen 1 was basic image intensification ('Starlight'), Gen 2 added the microchannel plate for better sensitivity, and Gen 3 improved the photocathode material and tube lifespan.

How Do Night Vision Goggles Work?

Veritasium

Education3 min read28 min video

Nov 4, 2023|7,891,886 views|206,395|6,106

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Key Moments

TL;DR

Exploring night vision: from active illumination to advanced image intensification and thermal imaging.

Key Insights

Night vision technologies fall into three main categories: active illumination, image intensification, and thermal imaging.

Active illumination is the simplest and cheapest, using an infrared light source, but suffers from delay and limited range.

Image intensification amplifies existing light thousands of times, offering a natural viewing experience with minimal delay, but requires some ambient light.

Thermal imaging detects infrared radiation emitted by objects, allowing vision in complete darkness and through fog/smoke, but has digital delays and cannot see lettering.

Military-grade night vision prioritizes passive, concealed operation and high resolution (measured in line pairs per millimeter) over active illumination.

Technological advancements like white phosphor improve readability, and generations of night vision (Gen 0-3) have evolved with increased sensitivity and durability.

UNDERSTANDING THE DARKNESS: CAMERAS VS. EYES

Cameras capture images by focusing photons onto a sensor, converting them into digital data. This can be enhanced by increasing ISO, which amplifies voltage. However, even high ISO settings on cameras struggle in near-total darkness, vastly outmatched by the human eye's low-light capabilities, especially when augmented by specialized night vision technology.

ACTIVE ILLUMINATION: THE BASIC APPROACH

The most affordable night vision, active illumination, works like a flashlight using near-infrared (NIR) light invisible to the human eye. A camera captures this NIR light and displays it on a screen. While common in commercial goggles and security cameras, this method has drawbacks: a noticeable delay between seeing and reality, causing motion sickness, and a limited range dictated by the NIR light source, making it impractical for military use due to its detectability.

IMAGE INTENSIFICATION: AMPLIFYING THE NIGHT

Image intensification, the core technology in military-grade night vision like the PVS-31As, drastically amplifies existing light instead of creating its own. Photons enter a tube, hit a photocathode to release electrons, which are then multiplied thousands of times via a microchannel plate, and finally strike a phosphor screen to create a visible image. This process offers thousands of times more brightness with minimal delay, enabling near-daylight vision.

THE MILITARY EDGE: RESOLUTION AND CONCEALMENT

Military night vision goggles, such as the PVS-31As and the advanced GPNVG-18s, eschew active illumination for passive, concealed operation. Their performance is measured in line pairs per millimeter, a metric of resolution critical for discerning details at a distance. Generations of development, from Gen 0 to Gen 3, have focused on improving sensitivity, durability, and reducing distortions, with Gen 3 utilizing semiconductor photocathodes for superior photon-to-electron conversion.

WHITE PHOSPHOR AND FIELD OF VIEW IMPROVEMENTS

Traditional night vision displays are green due to historic phosphor choices, but the human eye's low-light sensitivity peaks in the blue spectrum. Newer technologies, like white phosphor used in some PVS-31As, render the image with a blueish tint, improving detail perception. While effective, a significant limitation of many image intensification goggles is a narrow field of view, which advanced multi-tube systems like the GPNVG-18s aim to overcome by providing a wider, more immersive viewing experience.

THERMAL IMAGING: SEEING HEAT BEYOND LIGHT

Thermal imaging operates on a different principle, detecting infrared radiation emitted by objects, not reflecting visible or NIR light. This allows it to function in absolute darkness, fog, or smoke, and provides advantages like seeing buried objects. However, it's a digital system with motion delays and cannot read text, as it misses details reliant solely on reflected light. High-end thermal cameras are also less portable and power-hungry than image intensifiers.

THE LIMITATIONS AND FUTURE OF NIGHT VISION

Each night vision technology presents trade-offs in resolution, delay, operation in specific light conditions, concealment, and portability. While military-grade image intensification offers minimal delay and superb resolution, it requires some ambient light. Thermal imaging excels in complete darkness but suffers digital lag. Ongoing research aims to extend infrared detection ranges, reduce noise, and improve the efficiency of these technologies, with applications reaching far beyond the military into search and rescue, firefighting, and even space exploration.

Mentioned in This Episode

●Products

●Software & Apps

●Companies

●Organizations

●Concepts

●People Referenced

Night Vision Goggle Guide

Practical takeaways from this episode

Do This

Understand the three main types of night vision: active illumination, image intensification, and thermal imaging.

Choose active illumination for the cheapest option, but be aware of light emission and potential delays.

Opt for image intensification for military-grade performance that amplifies existing light with minimal delay.

Consider thermal imaging for complete darkness, fog, or smoke, as it detects heat signatures.

Be aware of limitations like field of view, resolution, and power consumption for each type.

Experiment with white phosphor for potentially better detail perception compared to traditional green phosphor.

Seek specialized goggles like the GPNVG-18 for enhanced field of view and advanced capabilities, if budget allows.

Avoid This

Do not rely solely on active illumination for stealth operations due to its light emission.

Avoid expecting perfect vision in absolute, complete darkness with image intensification; it requires some ambient light.

Do not expect thermal imaging to detect text or details visible only by reflected light.

Do not use night vision goggles in extremely bright light for extended periods, as it can saturate components.

Be cautious of motion sickness and disorientation with digital night vision systems due to processing delays.

Common Questions

Night vision goggles work by either amplifying existing low light (image intensification), creating their own light that's invisible to the human eye (active illumination), or detecting heat signatures (thermal imaging). Each type uses different technologies to allow vision in low-light or dark conditions.

Topics

Night Vision Image Intensification Active Illumination Thermal Imaging Low-light Photography Camera Technology Generations Of Night Vision Resolution Field Of View

Mentioned in this video

productChandra X-ray Observatory

A space telescope where the microchannel plate technology, originally developed for night vision, is used.

conceptactive illumination

The simplest and cheapest form of night vision, which uses near-infrared light emitted by the device and captured by a camera.

conceptline pairs per millimeter

The unit of measurement for resolution in night vision tubes, indicating how many pairs of lines can be resolved within one millimeter.

conceptphosphorous screen

A screen in image intensifier tubes that glows when hit by electrons, converting their energy back into visible photons.

conceptphotocathode

A component in image intensifier tubes that emits electrons when struck by photons.

conceptimage intensification

A type of night vision technology that amplifies existing light in the scene, used in military-grade goggles.

conceptmicrochannel plate

A component in image intensifier tubes made of many tiny channels that amplify electrons, creating an electron avalanche.

conceptwhite phosphor

An upgrade to the traditional green phosphor in night vision goggles, which appears slightly blue and can make it easier for the human eye to distinguish details.

conceptthermal imaging

A type of night vision that detects the infrared radiation emitted by objects, allowing visibility in complete darkness.

productPVS-31A

A high-end model of night vision goggles used and tested in the video, known for image intensification.

productGPNVG-18

The most expensive night vision goggles, which use four tubes of image intensification to fill the user's field of view.

conceptrods and cones

Types of photoreceptors in the human retina; cones are for color vision in light, while rods are for low-light vision and peak sensitivity in the blue spectrum.

organizationMarine Corps

Mentioned by a speaker as their service background, where they first used night vision technology.

conceptISO

A camera setting that boosts voltage to make images brighter, similar to how some night vision technologies amplify light.

conceptPlanck's law

A physics law describing the relationship between temperature and the electromagnetic radiation emitted by an object, relevant to thermal imaging.

toolOperation Iraqi Freedom