BODY TEMPERATURE CHECKS AT MACAO BORDERS

With a jurisdiction of 10,000 square miles, including 120 miles of border between Arizona and Mexico, the Pima County Sheriff's Department has a big responsibility. But infrared thermal imaging technology is giving the department a new way to cover all that ground.

Deployed during a nighttime drug smuggling surveillance effort, thermal imaging technology helped officers easily spot suspects crossing the border, with drugs stuffed in their backpacks. In the first four nights of using the technology, officers returned with suspects and confiscated drugs every night.

Infrared (IR) thermal imaging cameras provide another set of eyes for border control professionals and help them meet the demands they face.

Infrared thermal imaging cameras equip border control personnel with a whole new way of looking at the world. In simplest terms, thermal imagers operate like the human eye, but they are much more powerful. Energy from the environment comes through a lens and is registered on a detector. In the case of the infrared thermal imager, that energy is heat rather than light. By measuring very small relative temperature differences, invisible heat patterns are converted by the thermal imager into clear, visible images that the human eye can see through a viewfinder or TV monitor.

All objects that are not at absolute zero temperature (0 degrees K or -459.67 degrees F) emit various types of electromagnetic radiation including infrared. The hotter an object gets, the more infrared radiation is emitted as a result of the thermal agitation of its molecules and atoms. The spectral distribution or wavelength of this energy depends on the nature of object (i.e. its relative effectiveness as a radiator, called emissivity) and upon its temperature. Blacker colors and duller surfaces usually have a higher emissivity and radiate infrared energy more effectively. Lighter colors and shinier surfaces radiate less effectively.

Because the energy being sensed is heat and not light, thermal imagers can be used in both daytime and nighttime operations to find people, avoid obstacles or detect fire hot spots. Due to their own levels of infrared heat energy, people are easily seen 24 hours a day. Thermal imagers are usually very sensitive and can detect temperature variations as small as 0.1 degrees centigrade, even in less than ideal environmental conditions. Since they are unaffected by the amount of light in a scene, they won't "bloom" or shut down in direct light.