Infrared thermography is one of the fastest growing forms of non-destructive testing in the world today. The ways in which we can use this technology are only limited by our imagination. The basic premise behind this discipline is that all objects above absolute zero (-459°F, -273°C) give off invisible infrared radiation when a suitable medium is present (a gas or a vacuum).

The First Law of Infrared Thermography:
Infrared instruments “see” infrared radiation from the 1st 1/1000 of an inch of the surface of most solids and liquids.

Therefore:

• They do mot measure or see temperature!
• They do not “see through” most solids or liquids.

Infrared thermography is one of the fastest growing forms of non-destructive testing in the world today. The ways in which we can use this technology are only limited by our imagination. The basic premise behind this discipline is that all objects above absolute zero(-459 F, -273 C) give off invisible infrared radiation when a suitable medium is present (a gas or a vacuum). This radiation is a function of a number of different object characteristics, only one of which is temperature. Many are under the assumption that an infrared device measures temperature. The truth is, infrared radiometers, whether they are a simple $100 small hand held radiometer or a $100,000 precise imaging radiometer, do not measure temperature. They all only measure radiated energy given off from the first 1/1000 of an inch. This energy may or may not be a function of the subject’s temperature. In many cases though, a trained thermographer armed with the necessary knowledge is capable of calculating a very precise temperature.

The thermographer measures the temperature of a target. You have to put the proper data into the camera in order to get accurate temperature measurements. This means that setting up your camera before an inspection is important. It is also important to realize that you will be changing some of these settings in your camera during your inspection. (Of course this depends on the scope of equipment that you’re inspecting.) When we measure anything we compare it to a standard. Keep in mind that temperature measurements can be relative to the overall environment.