If you've entered a bank, post office, or airport in the past year, you've probably had your temperature taken. It probably wasn't with the traditional glass, liquid-filled thermometer many older folks are familiar with.

Instead, these days, one's temperature can be taken by relatively new devices that are accurate, easy to use, and non-invasive. What are these temperature-taking devices and how do they operate?

　　One such device is known as an infrared thermometer. It may be held close to, but won't touch, a person's forehead. The infrared thermometer provides a digital readout of the person's temperature. It contains a lens that focuses heat energy onto a detector called a thermopile.

This heat is turned into electricity, which is then transmitted to another detector for measurement. The more electricity emitted by a target, the hotter the person or object is. Basically, infrared thermometers are heat detectors, recording a person's “heat signature.”

　　An infrared sensor may also be used. This is a much larger device that can measure temperature from a distance of several meters. A person's image can be seen on a screen that is similar to a television set. This infrared machine not only measures a person's temperature but also displays it.

The highest temperatures detected appear as bright red, while lower temperatures usually show up as orange or yellow. These machines can handle several people at a time, which is ideal for large buildings and major transportation hubs, like airports and subway stations.

　　Both the infrared thermometer and the infrared sensor are non-invasive, detecting and measuring infrared light frequency—the temperature of any object they focus on. These devices are helping medical professionals identify and then treat people showing signs of a fever.