 What is infrared? Sir William Herschel is credited with discovering infrared while conducting temperature experiments using a prism. He noted that sunlight passing through a glass prism “broke” into various colors of the spectrum (violet, indigo, blue, green, yellow, orange, red). Moving the thermometer from cooler to warmer colors showed an increase in temperature, and moving the thermometer beyond the red color rays indicated an even higher temperature increase. This area, “infrared” lies beyond red, beyond what the human eye can see. Infrared cameras (a k a infrared imagers and thermal imaging cameras) convert thermal energy that the eye cannot see into a visible picture, so we can discern otherwise invisible heat images emitted by objects and living things. Seeing these images displayed on the camera screen allows us to identify problems that could result in serious failure, harm, injury, or loss. Infrared technology was first developed by the U.S. Government in the mid-1950s. The first commercial-grade thermal imagers were available in the 1960s. Subsequent developments incorporating this technology have greatly increased the number of devices and variety of applications. In the 1990s, technology had reached the point where thermal imagers became a widely-acclaimed and increasingly popular search-and-rescue tool for firefighters. And now, every year brings better thermal imaging cameras that are smaller, lighter, stronger, and more capable.
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