The great NVG debate

Estimated reading time 11 minutes, 41 seconds.

Peek inside the hangars of any large or medium-sized airborne law enforcement operator in the U.S., and you’re apt to find several sets of night vision goggles (NVGs).

These game-changing devices have become essential tools for chasing suspects, conducting low-light searches, and saving lives at night. But NVG technology has evolved dramatically since the first certified goggles hit the non-military aviation market in 1999.

Today, many operators are weighing the benefits of green phosphor goggles — which law enforcement pilots have used for more than 20 years — against newer white phosphor goggles that provide a clearer, better-defined image in some environments.

While demand for white phosphor goggles has skyrocketed recently, and some experts see them as the next evolution of NVGs, green phosphor googles still have their place.

Germany developed the earliest known night vision devices in the late 1930s, shortly before the Second World War. The Allies caught up quickly, developing similar devices that could amplify light about 1,000 times brighter than their source.

These early systems were massive and conspicuous. They used large infrared searchlights carried on flatbed trucks that enemies could easily target and destroy.

Historians refer to these devices as “generation zero” night vision technology.

In collaboration with the Radio Corporation of America, the U.S. Army steadily improved night vision technology over the next few decades, and by the mid-1960s, they developed night vision devices that didn’t require an infrared illuminator.

These green phosphor devices were critical to U.S. military efforts during the Vietnam War, both on the ground and in the sky. U.S. soldiers frequently traversed jungle terrain at night, while U.S. Army helicopter pilots used modified NVGs for night missions.

After the Vietnam War, non-military helicopter operators saw natural applications for NVGs in the civil market — particularly for augmenting the capabilities in law enforcement, search-and-rescue, firefighting, and helicopter emergency medical services (HEMS).

In 1999, the U.S. Federal Aviation Administration (FAA) issued its first approval for NVGs in commercial flight to Rocky Mountain Helicopters for use in HEMS operations with MBB/Eurocopter Bo 105 aircraft.

The same year, Enloe Medical Center in Chico, California, received the first operational approval for unrestricted NVG use in a helicopter.

Through consultation with several industry stakeholders, including NVG manufacturers L3Harris and Harris Night Vision (now part of Elbit Systems), the FAA developed regulatory standards for NVGs that continue to evolve. Today, NVGs are standard equipment for most law enforcement operators in the U.S.

“The biggest benefit from utilizing NVGs is the increased situational awareness the entire crew gains by being able to identify hazards,” said Rolla Boggs, a pilot with the Ventura County Aviation Unit in Camarillo, California. “A great example of this is when the air unit conducts night hoist rescue operations, especially in the remote areas of our county … NVGs allow the crews to conduct these operations exponentially safer than if they were not equipped with NVGs.”

The science behind NVGs seems complicated, but only at first glance.

Put simply: NVGs amplify ambient light to levels the human eye can easily see, making it possible to clearly perceive objects and subtle movements in the dark.

NVGs capture light through lenses at the front of the goggles — the light is made up of fundamental particles called photons. When photons strike a light-sensitive surface in the goggles called a photocathode, they’re converted into electrons — subatomic particles that carry electricity around a circuit.

Then, a photomultiplier in the form of a microchannel plate (MCP) in the goggles amplifies the electrons — the visual equivalent of turning up the volume in a stereo system.

When the electrons exit the photomultiplier component, they hit a phosphor screen that resembles an old-school television or computer monitor. Phosphor is a solid material that projects light when it’s exposed to an electron beam, ultraviolet light, or another form of radiation.

Finally, the phosphor screen in NVGs converts electrons back into visible light so pilots and aircrews can see the amplified image.

Green phosphor (P43) goggles display visible light in various shades of green, set against a black background. White phosphor (P45) goggles reproduce white images against a black background.

The result is a clearer, better-defined and more starkly contrasted image with white goggles that makes it easier to see small details, but some experts say green goggles are still adequate in many flying situations.

“You shouldn’t just go to white phosphor because that’s the newest thing,” said David Luke, co-founder and vice president of Night Flight Concepts, an NVG retailer and maintenance company in Waco, Texas. “It has its application … but white phosphor is definitely the hottest item of the last two or three years [in terms of demand from customers].”

Both green phosphor and white phosphor NVGs do a good job of helping aircrews see in the dark. The main difference in effectiveness depends on where you’re flying.

In low-light rural and remote areas, white phosphor goggles perform better due to sharper contrast and better definition, which leads to superior image quality.

If you’re chasing a suspect in the countryside or over snowy terrain, it’s easier to perceive small details with white phosphor goggles, like whether or not the suspect is brandishing a weapon.

“You just get more resolution, more acuity from that device in-low light conditions,” said Dr. Joseph Estrera, president of Aviation Specialties Unlimited (ASU), an NVG company based in Boise, Idaho. “That’s why [the industry] has gravitated toward that technology.”

Still, green phosphor goggles may have an edge when flying in urban areas. City streetlights and vehicle headlights are sometimes amplified too brightly in white phosphor systems.

“As [white phosphor] was initially used for ground tactical operations, the brightness was set slightly higher than what was required for aviation operations, as requested by the customers for combat operations,” explained Chad St. Francis, vice president of business development and marketing at ASU.

He contends that when the brightness is turned down to acceptable light levels for aviation operations, they seem to work better for aviation customers.

“With any new technology, there is a learning curve to achieve the best results for the mission performed. Training is vital to proper use,” St. Francis said.

It’s also important to note that new green phosphor goggles have vastly improved over green goggles that hit the market five to 10 years ago.

Experts recommend testing demonstration units — both new green and white phosphor goggles — in real-world situations to determine which suits their mission. Every operating environment is unique, and pilot preference is another important factor to consider.

“There’s a lot of areas that white phosphor is king, and I can say the same for green,” Luke said. “It’s all about the environment you’re operating in. Ideally, if it was within budget, you should have both green and white phosphor NVGs in your inventory.”

As for price, white phosphor goggles tend to be slightly more expensive, but the difference is negligible: around US$150 in systems that cost between $10,000 and $12,000 each.

“It’s really kind of a wash at that point,” Luke said. “Yes, white phosphor is more expensive, but not to that scale of what the goggles cost individually.”

Although many operators are enthusiastic about white phosphor NVGs, some observers suggest that the use of white phosphor should be based on the environment and mission of the operator.

Metropolitan law enforcement operations may take off from city airports, which are brightly-lit and may not be well-suited to white phosphor goggles, some observers say.

But NVGs by design were created for low-light situations. The concern is not where operators take off from as much as the lower light environments where they may be responding to emergency calls.

Training and pilot education can assist with the proper use of both green and white phosphor goggles, but some pilots simply choose to stick with green phosphor goggles out of individual preference.

Every operating environment is unique, so it’s important to demo both types of systems to find the right fit.

“We try and reach out to every individual operator and try and educate them,” Luke said. “There’s actually not one answer [about which is best].”

“It’s not what you hear,” he said, referring to industry hype. “It’s, what is the best piece of equipment that can be used for your specific operation? Demos are available. We have them; I’m sure our competitors have them … educate yourself on the different applications of white and green, the pros and cons. Most of the cons are overcome by proper training, and they’re an equal platform as far as I’m concerned.”