The Heat Is On

Technology advancements bring a new breed of affordable thermal cameras to the market

When many security professionals think of thermal security cameras, they think of exotic cameras with long-range, high-resolution performance that can cost as much as a nice car and feature applications befitting their high-end status: border security, huge industrial facilities and the like.

Recent advances in the design, fabrication and mass production of uncooled thermal detectors—which is usually one of the most expensive parts of a thermal camera— have led to a new breed of security camera. These thermal cameras are based on uncooled vanadium oxide microbolometer detector technology and are available for less than you might think, opening up a whole new class of applications.

The Best Way to See at Night
Thermal security cameras allow people to see what their eyes can’t—invisible heat radiation emitted by all objects regardless of lighting conditions. Thermal cameras detect the minute temperature differences between objects and turn them into video that can be watched on almost any TV monitor.

Because they see heat, not light, thermal cameras are effective security tools in any environment. They can easily detect intruders and other potential hazards to the security of a home, day and night, in good weather and bad.

CCTV cameras and our eyes both make images from reflected light. This is light energy that hits something, bounces off, is received by a detector and is then turned into an image.

Cameras based on visible light have the advantage of creating images that are familiar and easy to interpret. Unfortunately, the ability of a given detector—be it in an eyeball or a camera—to create these images relates directly to the amount of light available.

At night, for instance, when there isn’t much visible light to work with, we are limited to starlight, moonlight and artificial lights to help us see. If there isn’t enough light, we can’t see.

Another limitation of cameras that create images from reflected visible light is contrast. Like your eye, these cameras create better images if the object you are looking for has lots of contrast compared to its background. If it doesn’t, you won’t see it. That’s how camouflage works; camouflage is essentially a way of decreasing the visible contrast between an object and its surroundings.

Thermal cameras don’t suffer from the basic limitations of visible-light imaging, either. First, thermal cameras make pictures from heat, having nothing to do with reflected light energy. They see the heat given off by everything under the sun. Everything encountered in daily life creates heat energy, called a heat signature, that a thermal imager can see.

Not only does everything have a heat signature, but these heat signatures create their own contrast. What’s more, the thermal energy seen by thermal cameras generally creates a better image at night than during the day. They work just fine during the day—as long as there is the tiniest bit of temperature contrast between an object and its background, you can see it—but they work best at night. And nighttime, as we all know, is when security professionals need the most help to see.

Residential Security
Thermal security cameras are an affordable option for any homeowner with a security system, and it’s important for security professionals to understand their technological advantages over other camera options.

Most people who have been in the security business for any length of time know that thermal cameras let you see at night, but that’s only scratching the surface. With a thermal camera, homeowners can see into those dark, shadowy nooks and crannies that are common around house entrances and garages.

With thermal cameras, homeowners can watch property in ways that visible light cameras can’t, seeing intruders advancing toward a house without security lights that are both expensive to install and intrusive to those living around them.

Most people who buy large pieces of property want privacy. They don’t want to light themselves and their neighbors up at night with security lights.

Still, the most common way of seeing around a house at night is to install clusters of powerful lights. These may deter intruders, and they do help property owners and law enforcement personnel to see what’s going on at night, but security lights have disadvantages. There are many areas—along waterfronts and wetlands—where installing an effective lighting infrastructure is prohibitively expensive.

Even in areas small enough to be illuminated efficiently, security lights are often counterproductive, telegraphing the intent to guard something. Whether they help security professionals see anything with their visible light cameras at night is debatable.

Security lights may illuminate a residence, but often they spill over to surrounding properties. This light pollution is intrusive and often results in unnecessary tension between homeowners. Thermal cameras, on the other hand, work without anyone knowing they are there.

Another benefit of thermal cameras is that they maintain the privacy of neighbors. Because thermal cameras can’t identify facial features, homeowners can use them without sacrificing the modesty of their family members or that of their neighbors.

When considering which cameras are suitable for installation in a residential security application, bear in mind the range requirements. Most residential security situations don’t need cameras to distinguish whether a person is carrying a gun or a shovel from 10 miles away. Their range requirements are much more modest: a 19- or 35-millimeter lens set coupled with a detector of 320x240 resolution should be adequate for most situations. For covering areas with even shorter-range requirements, like those immediately adjacent to the residence, you can get sufficient performance out of a 6-millimeter lens and a 160x120 detector.

Welcome to the Dome
When most of us think of domes in the security world, we think of those smokedplastic things stuck to the ceiling with an inexpensive visible light camera inside. Replacing that visible light camera with a thermal camera may seem rather counterintuitive at first—why place a thermal camera inside?—but thermal can offer some distinct advantages.

The first thing security professionals and consumers need to do when contemplating indoor thermal dome cameras is to change the mindset about the cameras’ use. Thermal dome cameras play as big a role in safety as they do in security.

When the lights go out, thermal dome cameras let security and safety professionals survey buildings, quickly and safely ensuring that everyone is out of the area.

Likewise with fire. Thermal cameras see clearly through smoke—especially longwave cameras that use inexpensive VOx detectors—and are perfect tools for finding people in smoky rooms. Firefighters have used thermal cameras to see through smoke for years; thermal cameras are a proven technology for this application. With a thermal dome camera, facilities and security professionals can route rescue personnel to victims trapped by or overcome with smoke—without making them wait for a time-consuming room-toroom search in order to be rescued.

Indoor thermal dome cameras are being used for this reason in prisons— safety and evacuation during fire, not just security. One prison has dealt with increasing instances of inmates setting fire to their mattresses. The dense smoke from these fires makes it impossible for corrections officers to use their CCTV cameras to remotely verify that all inmates have evacuated the area. To ensure that all inmates are out, officers and firefighters must check each cell in person—a dangerous task in limited visibility. Once prison and fire officials saw how well thermal cameras could see through smoke, their safety advantages became clear, and the fire marshal mandated installation.

Another indoor use for thermal cameras is door access control. Few conditions are more challenging for a visible light camera than to be inside a building and looking out an external access door. When someone opens that door, the visible light camera quickly becomes oversaturated with light until its automatic gain controls can adjust. Then the door closes, and the camera is plunged into darkness.

Because thermal cameras see heat, not light, they don’t have any of these limitations. Coupled with a simple video analytics tripwire alarm, a thermal dome camera can give instant and reliable feedback of door access. Why use a dome for door monitoring? Good question—most people opt for a dome because it is more discreet and harder for people to see. Plus, it’s always good to have the pan and tilt capability near an access point.

Thinking Outside the Box
Some people are still stuck in the mindset that thermal security cameras are only used for long-range applications and are so expensive that only governments can afford them. Thermal cameras see during the day, at night, and in conditions of limited visibility like smoke. And, they’re inexpensive enough to be used anywhere, even at home.

As an illustration, no one would have considered using a thermal camera in an agricultural setting only a few years ago, but an exciting and emerging market for thermal security cameras now is on ranch and range land. Cattle and horses are expensive investments, and farmers and ranchers can’t risk losing them to theft, vandalism, poaching or predators.

By installing some affordable VOx thermal security cameras in a barn or in more remote pastures, farmers can watch over their animals and help ensure against their loss.

Because uncooled VOx thermal security cameras are affordable and widely available, uses are only limited by the security professional’s ability to think outside the box. Investigate this exciting, affordable technology, and your imagination will run wild.

This article originally appeared in the July 2008 issue of Security Today.

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