A police chase at night ends safely because a helicopter with a forward-looking infrared imaging system tracks the fleeing vehicle. Military forces use night-vision gear to see in the dark. Investigators find evidence of leaky pipes inside a building's walls. All these scenarios are linked by the technology of infrared (IR), or thermal imaging.

Originally developed for night vision and other military uses, thermal imaging technology recently has become available to professionals in other fields, opening the doors to new problem-solving tactics.

To understand the techniques of thermography, it is useful to understand how light and electromagnetic energy travels. The great 17th century physicist, Isaac Newton, used a prism to split a beam of light into a rainbow, demonstrating that light is made up of individual colors, or wavelengths, of energy, known as the spectrum. When you see a rainbow, you see those individual colors: red, orange, yellow, green, blue, indigo, violet.