Q+A CENTER

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. Just like the human eye, these cameras create better images if the object they are looking for has lots of contrast compared to its background. If it doesn’t, they won’t be able to see it. That’s how camouflage works; it’s essentially a way of decreasing the visible contrast between an object and its surroundings.

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

Not only does everything have a heat signature, but these heat signatures create their own contrast, so 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.

An important tactical distinction to understand is that security operators, law enforcement officers, and federal agents aren’t using thermal cameras to identify suspected criminals and terrorists. They use thermal cameras to detect the presence of people in restricted or suspect areas, assess the tactical situation, and respond accordingly. Because no one can hide their heat, thermal security cameras are the best tools officers and agents can use to know how many intruders they’re facing, and consequently how many officers or agents should respond to meet the threat.