Night Vision: How it Works, How it Helps

Oct. 16, 2001 -- Al Qaeda soldiers may know the terrain better and they may be able to navigate hidden networks of underground tunnels. But once night falls, any American troops in Afghanistan will have at least one advantage:

They can see in the dark.

"Clearly night vision technology is essential. It's one of the real trump cards we have in the battle with al Qaeda," said Michael O'Hanlon, a defense specialist at the Brookings Institution in Washington, D.C. "Otherwise, it would be a small number of forces fighting a small number of troops on their own turf. This is an important edge and we need every edge we can get."

Night vision devices were invented during World War II for use by American, British and Soviet soldiers and pilots. Since then, the technology has evolved from bulky devices that amplify light about 1,000 times to compact equipment that can amplify any light source (including faint starlight) up to 50,000 times, and eyewear that allows soldiers to see in complete darkness (such as in caves) by detecting heat differences.

Taliban May Have Some Night Vision Tech

Taliban and al Qaeda forces may have access to some night vision equipment, bought from other countries in the past. Last February, for example, a U.S. pilot of Egyptian origin recounted to a New York court how he flew a private jet for Saudi exile and alleged terrorist mastermind Osama bin Laden and transported in equipment from Britain including night-vision goggles.

Night vision equipment has also long been available to consumers in the United States and elsewhere, although it is a felony to leave the United States with the technology without a permit.

But experts believe that any equipment al Qaeda forces may have is scarce, and inferior to U.S. technology.

"The Taliban doesn't seem to have experience with night vision equipment," said Anthony Cordesman, an ABCNEWS defense consultant and senior fellow at the Center for Strategic and International Studies. "So this equipment offers a lot of advantages."

Some have pointed out that the Soviets had access to night vision equipment during their drawn-out conflict with Afghanistan in the 1980s and still the Soviets were forced to withdraw from that conflict. But Cordesman says equipment and training among U.S. forces far exceeds whatever Soviet troops had more than 20 years ago.

"We have the technology," he said. "So 'We own the night' could take on new meaning."

Already, U.S. pilots have used night vision equipment to navigate and find targets during night bombings of Afghanistan. Infrared lasers are also used to illuminate targets with a light invisible to the naked eye, but visible to those using infrared detection technology. Infrared images are portrayed in shades of color onto a TV screen in the cockpit.

"Being able to operate around the clock, in the day and the night, is vital for the air forces because it places great uncertainty in the minds of the opposition," said Nick Cook, aviation consultant for Jane's Defense Weekly.

Amplifying Light, Seeing by Temperatures

Night vision equipment falls into two major categories: image intensification systems and thermal devices.

Even when a night appears completely dark, near-infrared light is emitted by the moon and stars. A night vision device amplifies this light to visible levels. The light, which is made up of photons, is converted into electrical energy and then accelerated through a thin disk called a microchannel plate. As the converted photons strike a phosphorus screen as electrons, they are perceived through an eyepiece in shades of green.

"The reason it's in green is because when you put the unit down, you want your eyes to remain dilated so you can see in dim light," said Rich Urich, director of operations at Night Vision Equipment Company in Prescott Valley, Ariz. "Use most any other color and your pupils will constrict when you take off the unit."

Infrared technology measures fraction of a degree differences of heat given off by objects. All living things and many objects — people, animals, recently used cars — emit heat in the form of infrared radiation. Infrared radiation is a part of the electromagnetic spectrum just below ("infra") the frequency of red light. Infrared devices read heat by absorbing infrared light, converting it into a grid of video signals and creating a picture the viewer can see.

Effective in Winter

Urich explains, while viewing through an infrared device: "you'll see varying shades of gray or black, with the whitest segments representing those giving off the most heat." Some reports have suggested that infrared technology will become more effective as winter arrives in Afghanistan, since contrasts between body temperatures and the external temperatures will increase. But Urich claims the contrast doesn't necessarily enhance infrared images, and once snow falls, the opposite is true.

"Infrared systems are very sensitive to white," he says. "The images can be compromised if there is snow everywhere."

Infrared devices might not only prove useful to ground troops and pilots for vision, they can also help detect recent footprints or tire tracks that could still be emitting heat. Even objects that have recently been touched, like a desk or door, can show traces of the recent activity.

Besides military use, infrared technology has proven useful in many other applications. Law enforcement use it to detect criminals operating at night, border patrol use it to monitor for illegal crossings, ranchers use it to hunt nocturnal predators such as coyotes and drivers in some specially-outfitted automobiles use it for better vision during night driving. The technology can also help create a thermal image of a home to find leaks and improve insulation.