IR Temp Sensor FAQ

Hello Friends,

Infrared temperature sensors have been around a bit longer than most people realize; about 80 million years, in fact. Reptilia Squamata Serpentes beat us to the infrared punch quite some time ago, but we primitive humans are beginning to catch up in terms of accuracy, imaging and versatility.

Infrared Thermeters: An infrared thermometer (a.k.a. IRT or non-contact thermometer) is a device that can measure an object's temperature without physically touching it. IRTs have two primary benefits when compared to contact thermometers: They can provide fast and accurate surface temperature measurements of hazardous or hard to reach areas, and can provide several readings per second. The latter is a huge advantage over contact-type thermometers, which rely on heat conduction and must be allowed to cool before they are used again.

Infrared and Heat: Infrared radiation can be thought of as a wavelength of light that is just outside of our visual range, as its electromagnetic frequency falls somewhere between the visible wavelength and radio waves. Infrared radiation is emitted by any object warmer than absolute zero, and can be measured in the same way as any other electromagnetic signal. Using absolute zero as a baseline, an object's heat can be measured in direct proportion to the amount of infrared energy it produces.

Dust, Steam and Smoke: Because they rely on an unobstructed "view" of the target, older infrared thermometers often had trouble seeing through aerial dispersants. At best, these contaminants would disperse the infrared energy, making for a cloudy image and inconsistent reading. At worst, they could obstruct the signal altogether. Modern IRTs often utilize an element that can pick up on multiple wavelengths (colors) at once, and cross-reference the data to extrapolate the subject's temperature.

Flame Temperature: Open flame is notoriously difficult to measure with IRTs, as the visible spectrum of flame actually emits very little infrared. However, at some wavelengths, the flame's temperature can be extrapolated by measuring the carbon-dioxide gases in the flame. This capability necessitates an IRT with wide-range sensing ability, which most do not have.

Calibration: IRTs must be periodically calibrated to maintain accuracy. The IRT is focused on what the industry considers a "black body," or an object that absorbs all electromagnetic radiation that falls on it. While a true black body is almost impossible to obtain within the realm of conventional physics, it is possible to emulate the effect with a 97 to 99 percent accurate "gray body box." These "black body simulators" have a number of angled reflectors inside that effectively absorb and disseminate radiation in a temperature-controlled environment, allowing for calibration of the IRT at near ideal conditions.

Thanks and Regards
Steven Brooks