HOWNIGHTVISIONWORKS
Updated: January 9, 2023

How Night Vision Works

How night vision works: Everything you always wanted to know about night vision including low-light imaging techniques, thermal imaging and near-infrared illumination.
Written by: Christopher Mark
Edited by: Mark Spence
Fact-Checked by: Patricia John

Introduction

In the natural world, there is a continuous spectrum of light that ranges from infrared radiation to visible light to ultraviolet radiation. Humans can see only a small portion of this spectrum, which is called visible light. This visible light is electromagnetic radiation that is visible to the human eye.

Night vision is the ability to see in low light conditions. This technology uses a variety of methods to amplify available light, making it possible to see in complete darkness. The most common type of night vision technology is image intensification, which uses a specialized camera and a phosphor screen to amplify ambient light and create a visible image. Other types of night vision include thermal imaging and active illumination. Night vision technology is used in a wide range of applications, including military operations, surveillance, hunting, and wildlife observation.

How do we see in the dark?

The human eye is a complex organ that allows us to see in a variety of lighting conditions. The eye contains several different parts that work together to allow us to see. The most important part of the eye for seeing in the dark is the retina.

The retina is a thin layer of tissue that lines the back of the eye. The retina contains millions of tiny cells called rods and cones. These cells convert the light that enters the eye into electrical signals that can be processed by the brain

Infrared Light

Credit: https://en.wikipedia.org/

Infrared light is a type of electromagnetic radiation that is not visible to the human eye. It has a longer wavelength than visible light and falls in the spectrum between microwaves and visible light. Infrared light is emitted by all objects that have a temperature above absolute zero. The amount of infrared radiation emitted by an object increases as its temperature increases.

Infrared light can be split into three categories: near infrared, mid-infrared, and far infrared.

Near infrared (NIR)

NIR has the shortest wavelength and is closest to visible light. It ranges from 780 nm to 1400 nm. It's used in various applications such as night vision goggles, remote controls, and fiber-optic communications.

Mid-infrared (MIR)

MIR ranges from 1400 nm to 3000 nm. It's used in applications such as thermal imaging, spectroscopy, and chemical analysis.

Far infrared (FIR)

FIR has the longest wavelength and ranges from 3000 nm to 1 mm. It's used in applications such as thermal imaging, sensing, and heating.

Each of these categories has its own unique properties and applications. It's important to note that the boundary between these categories is not fixed and may vary depending on the source or context.

Thermal Imaging

ThermalImaging
Credit: https://en.wikipedia.org/

Thermal imaging technology uses infrared light to create an image of an object. A thermal camera detects the infrared radiation emitted by an object and converts it into an image. The image produced by a thermal camera is called a thermogram. In the thermogram, warm objects appear as bright colors, and cold objects appear as dark colors.

Thermal imaging is particularly useful for detecting objects in complete darkness or in conditions where visibility is limited. It can also be used to detect objects that are hidden by smoke or fog. Thermal imaging technology is used in a wide range of applications, including thermal imaging scope, thermal imaging monocular, surveillance, search and rescue, and military operations.

How Thermal Imaging Cameras Work

Thermal imaging cameras use a lens to focus the infrared radiation onto a detector. The detector, typically made of a material called mercury cadmium telluride (MCT), converts the infrared radiation into an electrical signal. This signal is then processed by the camera's electronics to create an image.

Some thermal imaging cameras use a cooled detector, which is cooled to a temperature below that of the environment. This helps to reduce the amount of noise in the image, resulting in a clearer and more detailed image.

Thermal imaging cameras can vary in resolution, with some cameras having a resolution of just a few hundred pixels, while others have a resolution of thousands of pixels. The resolution of the camera determines how much detail can be seen in the image.

Applications of Thermal Imaging

Thermal imaging has a wide range of applications, including:

Building inspections:

Thermal imaging cameras can be used to detect insulation and air leakage in buildings, which can help to improve energy efficiency.

Electrical inspections:

Thermal imaging cameras can be used to detect hot spots in electrical systems, which can indicate potential problems before they cause a failure.

Search and rescue:

Thermal imaging cameras can be used to find missing people in dark or smoke-filled environments.

Medical imaging:

Thermal imaging cameras can be used to detect temperature changes in the body, which can indicate the presence of certain medical conditions.

Surveillance:

Thermal imaging cameras can be used to detect people or vehicles in darkness or poor visibility conditions.

Types of Thermal Imaging Devices

Credit: https://en.wikipedia.org/

The different types of thermal imaging devices, including un-cooled and cryogenically cooled cameras.

Un-cooled Thermal Imaging Devices

Un-cooled thermal imaging devices are the most common type of thermal imaging cameras. These cameras use a detector that is not cooled, which means they can be made smaller and more affordable than cooled cameras. They are also more rugged and can withstand harsh environments.

Un-cooled thermal imaging cameras use a detector made of a material called microbolometer. This detector converts the infrared radiation into an electrical signal, which is then processed by the camera's electronics to create an image. The image is typically displayed in shades of gray, with warmer objects appearing as white or yellow and cooler objects appearing as black or blue.

Un-cooled thermal imaging cameras are commonly used in a wide range of applications, including building inspections, electrical inspections, search and rescue, and surveillance. They are also popular in the consumer market, as they can be used for DIY home repairs and outdoor activities.

Cryogenically Cooled Thermal Imaging Devices

Cryogenically cooled thermal imaging devices use a cooled detector, which is cooled to a temperature below that of the environment. This helps to reduce the amount of noise in the image, resulting in a clearer and more detailed image.

The detector in a cryogenically cooled thermal imaging camera is typically made of a material called mercury cadmium telluride (MCT). This detector converts the infrared radiation into an electrical signal, which is then processed by the camera's electronics to create an image.

Cryogenically cooled thermal imaging cameras are commonly used in applications that require a high level of image detail, such as scientific research, industrial inspections, and medical imaging. They are also used in military and law enforcement applications.

Image Enhancement

Image Intensifier
Credit: Wikipedia

Image enhancement technology is used to amplify available light and create a visible image. The most common type of image enhancement technology is image intensification. Image intensification technology uses a specialized camera and a phosphor screen to amplify ambient light and create a visible image.

The camera captures the available light and focuses it onto a photocathode, which converts the light into electrons. The electrons are then amplified by a microchannel plate and directed onto a phosphor screen. The phosphor screen converts the electrons back into light, creating a visible image.

How Image Enhancement Works?

An image intensifier consists of several key components: the photocathode, the microchannel plate, and the phosphor screen.

The photocathode is a layer of material that converts photons into electrons. When light strikes the photocathode, it causes the electrons in the material to be emitted. The emitted electrons are then accelerated by an electric field and directed towards the microchannel plate.

The microchannel plate is a thin layer of glass with millions of tiny channels etched into it. The accelerated electrons pass through these channels and collide with the walls, causing a cascade of secondary electrons to be emitted. This process amplifies the number of electrons in the image.

The amplified electrons are then directed towards a phosphor screen, which converts the electrons back into photons. The phosphor screen emits light in proportion to the number of electrons that strike it, creating a brighter image.

Applications of Image Intensifiers

Image intensifiers are used in a variety of applications, including:

Night vision:

Image intensifiers can be used to enhance the visual quality of images captured in low-light conditions. They are commonly used in night-vision goggles and cameras.

Surveillance:

Image intensifiers can be used to enhance the visual quality of images captured by surveillance cameras, making it easier to identify objects and individuals in low-light conditions.

Medical imaging:

Image intensifiers can be used in medical imaging to enhance the visual quality of X-ray and fluoroscopic images.

Scientific research:

Image intensifiers can be used in scientific research to enhance the visual quality of images captured by telescopes and microscopes.

Night Vision Generations

Night vision technology has gone through several generations of development. The first generation of night vision devices used image intensification technology. The second generation added a microchannel plate to improve image quality. The third generation added an automatic gain control to improve image brightness and contrast. The fourth generation added a built-in infrared illuminator to improve visibility in complete darkness.

Generation 1

The first generation of night vision technology, also known as Gen 1, was developed in the 1960s. It uses an image intensifier tube, which amplifies the existing light in the environment to produce a visible image. Gen 1 night vision devices are relatively inexpensive and are commonly used for hunting and surveillance.

One of the main disadvantages of Gen 1 night vision is that it requires a certain level of ambient light to function properly. Without enough ambient light, the image produced will be too dark to be useful. Additionally, Gen 1 devices have a relatively low resolution and a narrow field of view.

Generation 2

The second generation of night vision technology, also known as Gen 2, was developed in the 1970s. It uses a microchannel plate, which increases the number of electrons in the image, producing a brighter and clearer image. Gen 2 night vision devices have a higher resolution and a wider field of view than Gen 1 devices.

One of the main disadvantages of Gen 2 night vision is that it is more expensive than Gen 1. Additionally, the microchannel plate in Gen 2 devices is prone to damage from excess heat and can be less durable than Gen 1 devices.

Generation 3

The third generation of night vision technology, also known as Gen 3, was developed in the 1990s. It uses an ion barrier film, which increases the lifespan of the microchannel plate, making Gen 3 devices more durable and reliable than Gen 2 devices. Gen 3 night vision devices have the highest resolution and the widest field of view of all the generations.

One of the main disadvantages of Gen 3 night vision is that it is the most expensive of all the generations. Additionally, Gen 3 devices are sensitive to bright light and can be damaged by exposure to sunlight.

Generation 4

Generation 4 is the latest generation of night vision technology and is currently under development. It is expected to have a higher resolution, wider field of view, and a more durable microchannel plate than previous generations. Additionally, it is expected to be more resistant to bright light and have a longer lifespan than previous generations.

Night Vision Equipments

Night Vision Devices

There are several different types of night vision equipment, each with its own unique features and capabilities.

Night Vision Goggles

Night vision goggles (NVGs) are devices that amplify available light, such as starlight, moonlight, and infrared light, to allow the user to see in darkness. They are typically used by military personnel, law enforcement, and wildlife researchers.

There are two main types of night vision goggles: image intensification and thermal imaging.

Image intensification goggles use a photocathode to convert incoming photons of light into electrons. These electrons are then amplified by a microchannel plate, creating a brighter image that is then projected onto a phosphor screen, allowing the user to see in low-light conditions.

Thermal imaging goggles, on the other hand, use infrared radiation to create an image of the environment. They detect the heat that is emitted by objects and convert it into a visible image. This allows the user to see in complete darkness and also to detect objects that are not visible to the naked eye.

Both types have their own advantages and disadvantages, with thermal imaging goggles being more expensive but also more efficient in total darkness and through obscurants, while image intensification goggles are cheaper but less efficient in these conditions.

Night Vision Scopes

Night vision scopes are specialized optical devices that are designed to be mounted on firearms, such as rifles and shotguns, to allow the user to see in low-light conditions. They work by amplifying available light, such as starlight, moonlight, and infrared light, to create a brighter image of the target.

Like night vision goggles, there are two main types of night vision scopes: image intensification scope and thermal imaging rifle scope.

Thermal Imaging

Thermal imaging, also known as infrared imaging, is a technology that uses infrared radiation to create images of objects or areas. These images are known as thermal maps, and they show the distribution of temperature across an object or area. Thermal imaging cameras can detect infrared radiation emitted by objects, even in complete darkness, and convert it into a visible image. This technology is commonly used in a variety of applications, including security, industrial inspections, and medical imaging. It is also used in wildlife observation and military reconnaissance.

Infrared Illumination

Infrared illumination equipment emits infrared light, which is invisible to the human eye. This allows the user to see in complete darkness, as long as they are wearing night vision goggles or using a night vision scope that is sensitive to infrared light. Infrared illumination equipment is commonly used by military personnel and law enforcement officers for navigation and surveillance in low-light conditions.

Night Vision Monoculars

Night vision monoculars, also known as night vision goggles, are handheld devices that allow the user to see in low-light conditions. They use an image intensifier tube to amplify the existing light in the environment to produce a visible image. Night vision monoculars are commonly used by military personnel, law enforcement officers, hunters, and outdoor enthusiasts for navigation and surveillance in low-light conditions.

Night vision monoculars come in different generations, which offer different levels of performance. Generation 1 monocular and Generation 2 night vision monoculars are less expensive but offer lower resolution and sensitivity compared to Gen 3 and 4.

Night vision monoculars also come with different features such as built-in infrared illuminators, digital zoom, and image recording capabilities. These features can enhance the performance and versatility of the monocular, but they also make them more expensive.

Night Vision Binoculars

Night vision binoculars use image intensification technology to amplify available ambient light, allowing the user to see in low light conditions. They can be used for a variety of activities such as coyote hunting, surveillance, and navigation. Some night vision binoculars use a single intensifier tube, while others use two for increased depth perception. There are also digital night vision binoculars which use a digital sensor and display instead of an intensifier tube. They are available in different generations, with the latest ones having better image quality and performance.

Applications of Night Vision

Hunting

Night vision technology has come a long way since its inception during World War II. Today, it is used in a wide range of applications, from military operations to hunting, wildlife observation, and even entertainment.

Military

The military has been one of the biggest users of night vision technology since its invention. Night vision goggles and scopes allow soldiers to operate in low-light conditions, giving them a tactical advantage over their enemies. These devices allow soldiers to navigate through dark terrain, conduct reconnaissance missions, and engage in combat operations at night. Night vision technology is also used in tanks and other military vehicles, as well as on aircraft and helicopters, to improve visibility and enhance situational awareness.

Law Enforcement

Law enforcement agencies also use night vision technology to improve safety and increase their operational capabilities. Night vision goggles and scopes are used by police and SWAT teams to navigate dark environments, such as buildings and streets, during nighttime operations. These devices also allow officers to conduct surveillance and make arrests in low-light conditions.

Hunting

Night vision technology has become increasingly popular among hunters and sportsmen. Night vision rifle scopes and goggles allow hunters to see in the dark, making it easier to track and hunt game, even at night. These devices also enable hunters to make more accurate shots, reducing the chances of wounding an animal.

Wildlife Observation

Night vision technology is also used in wildlife observation, particularly for bird watching. These devices allow ornithologists and bird watchers to observe nocturnal bird species, such as owls and nightjars, that are not visible to the naked eye during the day. Thermal imaging cameras are also used to detect the heat signature of birds, making it possible to observe them in complete darkness.

Surveillance

Night vision technology is used in surveillance to improve security and detect potential threats. Night vision cameras and scopes are used by security personnel to monitor buildings, streets, and other areas at night. These devices can also be used to detect intruders and other potential security threats in low-light conditions.

Security

Night vision technology is also used in the field of security to enhance the capabilities of security personnel. Night vision cameras, goggles, and scopes are used to monitor buildings, streets, and other areas at night, detect intruders and other potential security threats, and to improve the chances of capturing suspects.

Camping

Night vision technology has also found its way into the outdoor and camping industries. Night vision goggles for helmet enable campers and hikers to navigate through dark terrain at night, making it easier to set up camp, start fires, and find their way around.

Hidden-object detection

Night vision technology is also used to detect hidden objects or people. Thermal imaging cameras are used to detect the heat signature of people and objects, making it possible to detect them in complete darkness. This technology is used in search and rescue operations, as well as by law enforcement agencies to detect suspects hiding in dark places.

Entertainment

Night vision technology has also found its way into the entertainment industry. Night vision cameras and scopes are used in film and television production to capture footage in low-light conditions. These devices are also used in haunted house attractions and other entertainment venues to create a spooky and suspenseful atmosphere.

Night vision technology has come a long way since its inception. There are different types of night vision technologies available like Infrared, thermal imaging, and Image enhancement, each with its own unique advantages and applications. The technology has been developed to an extent where the fourth generation night vision equipment have the ability to improve visibility in complete darkness and give better image quality, contrast and brightness. The technology is widely used in military, surveillance and wildlife observation applications.

Frequently Asked Questions

How does night vision technology work?

Night vision technology works by amplifying available light, such as moonlight and starlight, to make it possible for the human eye to see in low-light conditions. The human eye is not able to see in complete darkness, as it requires a certain amount of light to function. Night vision devices, however, are able to amplify available light, making it possible for the human eye to see in conditions that would otherwise be too dark to see in.

What are the two main types of night vision technology?

The two main types of night vision technology are image intensification and thermal imaging. Image intensification works by amplifying available light using a photocathode tube, while thermal imaging works by detecting the infrared radiation emitted by objects.

How does image intensification work?

Image intensification, also known as active infrared, works by amplifying available light using a photocathode tube. This tube is made of a special material that is sensitive to light and is able to convert light into an electrical signal. The signal is then amplified and sent to a phosphor screen, which converts the electrical signal back into a visible image.

How does thermal imaging work?

Thermal imaging, also known as passive infrared, works by detecting the infrared radiation emitted by objects. All objects emit infrared radiation, but it is not visible to the human eye.

How far will I be able to see with Night Vision?

The distance you can see with night vision can vary depending on the type of equipment and the environment. Generally, you can expect to see several hundred meters in complete darkness.

What is an IR Illuminator and do I need one?

An IR illuminator is a device that emits infrared light to enhance the performance of night vision equipment. Whether or not you need one depends on the specific application and the ambient lighting conditions.

How durable is night vision equipment? What if I drop it?

Night vision equipment is generally durable, but it can be damaged if dropped or subjected to severe impacts. It is best to handle it carefully and store it in a protective case when not in use.

Is it legal to own Gen 3 night vision? And do I need any kind of permit?

It is legal to own Gen 3 night vision in most countries, but some countries may have restrictions on its use or export. It is best to check your local laws before purchasing.

What else can I do with night vision?

Night vision can be used for a variety of applications, including hunting, surveillance, and navigation.

Thermal vs Night Vision?

Thermal imaging and night vision are two different technologies. Thermal imaging detects infrared radiation emitted by objects, while night vision amplifies ambient light to create an image. Each has its own advantages and disadvantages, and the best choice depends on the specific application.

What do the generations mean for night vision devices & which ones are available?

The generations of night vision devices refer to the technology used and the level of performance. They are generally classified as Gen 1, Gen 2, Gen 3, and Gen 4.

What is a residual light amplifier?

A residual light amplifier (RLA) is a type of night vision device that amplifies ambient light to create an image.

What are some precautions to using Night Vision?

Some precautions to using night vision include avoiding pointing the device at bright lights, protecting the device from impact and moisture, and preserving the dark adaptation of your eyes before using the device.

What is the Best Way to Protect NVD?

The best way to protect a night vision device is to store it in a protective case when not in use, handle it carefully, and avoid exposing it to bright lights or impacts.

Can you get a night vision camera on your phone?

Yes, some smartphones have a night vision camera feature that uses software to enhance low light images.

How good is human night vision?

Human night vision is not as good as that of some animals, but the ability to see in low light conditions is called scotoma.

Which type of technology does night vision equipment use?

Night vision equipment typically uses image intensification or thermal imaging technology.

Which night vision technology 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?

Image intensification technology works by collecting and amplifying small amounts of light, including the lower portion of the infrared light spectrum, to make it visible to the human eye.

Which type of night vision 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?

Thermal imaging technology operates by capturing the upper portion of the infrared light spectrum, which is emitted as heat by objects.

According to the visible light color spectrum, which type of light has the most energy?

According to the visible light color spectrum, violet has the most energy.

According to the visible light color spectrum, which type of light has the least amount of energy?

According to the visible light color spectrum, red has the least amount of energy.

How many categories can infrared light be split into?

Infrared light can be split into three categories: near-infrared, mid-infrared, and far-infrared.

Which term is used to describe a particle of light?

A photon is used to describe a particle of light.

References

  1. Night vision: From Wikipedia, the free encyclopedia
  2.  Chijiiwa, Taeko; Ishibashi, Tatsuro; Inomata, Hajime (1990). "Histological study of choroidal melanocytes in animals with tapetum lucidum cellulosum (abstract)". Graefe's Archive for Clinical and Experimental Ophthalmology228 (2): 161–168. doi:10.1007/BF00935727PMID 2338254S2CID 11974069.
  3. ^ Milius, Susan (2012). "Mantis shrimp flub color vision test". Science News182 (6): 11. doi:10.1002/scin.5591820609JSTOR 23351000.
  4. ^ "The Human Eye and Single Photons".
  5. ^ "Sensory Reception: Human Vision: Structure and function of the Human Eye" vol. 27, p. 179 Encyclopædia Britannica, 1987
  6. ^ Bowmaker, J K; Dartnall, H J (1 January 1980). "Visual pigments of rods and cones in a human retina"The Journal of Physiology298 (1): 501–511. doi:10.1113/jphysiol.1980.sp013097PMC 1279132PMID 7359434.
  7. ^ Luria, S.M.; Kobus, D.A. (April 1985). "Immediate Visibility after Red and White Adaptation" (PDF). Submarine Base, Groton, CT: Naval Submarine Medical Research Laboratory (published 26 April 1985). Archived from the original (PDF) on 1 December 2012. Retrieved 25 March 2012.
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