How Night Vision Works

Night vision technology is becoming increasingly important to armed forces and police forces in their ability to operate in the dark, and to civilians in their security to protect their property or loved ones.

In this essay, we will look at how night vision works and its place in the world today. It is important to understand the technology in order to be able to assess its potential for the future.

Night vision technology is a relatively recent development that has been spurred on by the military needs during the 20th century and the associated technological developments. Although it may seem like a relatively new invention, it has actually been with us for a long time, since our early ancestors first began using fire.

Infrared Light

The night vision technology that we are most familiar with is “thermal” night vision. Images from this type of equipment are made possible by the use of infrared light.

Some animals, such as snakes and cats, can see infrared light, but humans cannot. However, we are able to see the effect of infrared light on objects around us.

Infrared radiation is “felt” as heat and is produced by all objects that have a temperature above absolute zero (-273oC). We are not able to see this radiation directly, however, because it is beyond the visible spectrum.

Thermal Imaging

Thermal imaging cameras detect radiation in the infrared spectrum and display images that show the distribution of heat in the environment. The image is presented as a series of colours – with white representing the hottest areas and black representing cold areas.

To the human eye, thermal images appear to have a glowing appearance. This effect can be enhanced by using an image intensifier that contains micro-lenses which intensify the light as it passes through.

There are two types of equipment used for thermal imaging:

Un-cooled –

These devices contain an infrared sensor that detects infrared radiation and converts it into an electrical signal. This electrical signal is then converted into a digital image and displayed on a screen for the user to view. The sensors used in uncooled devices are usually made from germanium, silicon or indium antimonide.

Cryogenically cooled –

These devices work in a similar way to uncooled devices, except that they contain a cryocooler which cools the sensor to cryogenic temperatures (below -50oC). This enables the device to be more sensitive to infrared radiation and increases its range of detection. Cryogenically cooled devices can detect infrared radiation from greater distances than uncooled devices.

Image Enhancement

The images produced by thermal imaging equipment are not always very clear or detailed. One of the ways in which this problem can be alleviated is by using image enhancement techniques such as:

Digital enhancement –

Digital enhancement involves converting the image into digital form and manipulating it using computer software. The image can then be manipulated in various ways to improve contrast, remove noise and enhance detail before being converted back into an analogue image for viewing.

Video enhancement –

Video enhancement involves using video processing techniques on successive video frames to improve upon the next frame in terms of clarity, contrast etc…

Generations:

Generation 0 –

These were devices designed during World War II by German scientists led by Manfred von Ardenne. They used “bombes” containing cathode ray tubes and thermocouples which detected infra-red light and converted it into visible images on a phosphor screen for viewing. They were called “Nachtseh Gerät” (Night Vision Equipment).

The Allies also had similar technology – it was used in artillery spotting and later in searchlights for aircraft navigation aids.

Generation 1 –

These devices were introduced during the Vietnam War (1955-1975) and were able to produce crude monochrome images at low resolutions due to their design limitations and use of early-generation electronics technology. They were large and heavy, but were still more compact than earlier models.

Generation 2 –

These devices were less bulky than earlier models, although they were still quite large by today’s standards; they were introduced during the early 1980s and were able to display black and white images at resolutions of up to 400 lines with frame rates of up to 15 frames per second (fps).

The image intensifiers used in these systems were cooled by liquid nitrogen or argon gas; this enabled them to achieve higher sensitivities than previous models at the cost of limited range due to their bulky design and power requirements.

This generation was also known as Generation 0+ due to its increased sensitivity over previous models. They were used primarily for land-based applications such as tank periscopes, helicopter gunships and observation posts, but also found use with naval forces for submarine detection purposes (the Russians claimed they could even detect submerged submarines using these devices).

Generation 3 –

These were the first generation devices to be used in combat by the British Army in Northern Ireland during the 1990s. They were also used in the first Gulf War (1990-1991).

These systems were smaller, lighter and more compact than their predecessors, although they cost more and had shorter ranges; they could display black and white images at resolutions of up to 1024 lines with frame rates of up to 60 fps, and had a maximum range of around 1,200 meters. They were cooled using a combination of liquid nitrogen and argon gas. These devices were also known as Generation 0++ due to their increased sensitivity over previous models.

Generation 4 –

These devices were designed by and for the US Army and became operational during 2003; they are still in use today.

Night Vision Equipment

Scopes –

These devices use thermal imaging technology to produce images of targets at night or in other low-light conditions; they are usually used with rifles or machine guns.

Goggles –

These devices consist of goggles with built-in imaging technology; they display infrared images directly in front of the user’s eyes and do not require any other equipment.

Cameras –

These devices use thermal imaging technology to produce images of targets at night or in other low-light conditions; they are usually used with night vision goggles or helmets. Thermal imaging cameras can also be mounted on vehicles or aircraft for surveillance purposes.

Applications for night vision

To date, night vision has found its greatest practical use with the military and armed forces around the world. However, there has been a recent trend for devices based on this technology to be used for civilian applications such as hunting and poaching, game viewing, security and surveillance etc.

Conclusion

Following the end of World War II (1945-1949), it was widely hoped that technological developments such as night vision would make future conflicts less bloody and less destructive than preceding conflicts such as those involving Napolean Bonaparte (1769-1821) or World War I (1914-1918), but this was not to be so – from Vietnam to Afghanistan and Iraq, war continues to bring death and destruction on a massive scale.

Night vision technology has helped armed forces overcome some of the challenges brought about by darkness but it has not made war any less bloody or any less destructive than it ever was; that may have been an unrealistic hope but it is one that cannot be entirely dismissed even today.

Perhaps we can expect to see more developments in night vision technology as time goes on – it could become more compact, cheaper and easier to use over time, but will it ever make war any less destructive? That remains to be seen…