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Keeping it simple is a principle for effective communications. When it comes to infrared thermography, oversimplification can be detrimental when it leads to confusion or misunderstandings.

In trying to explain the operation of thermal imagers, many will frequently state that infrared imagers sense temperatures across the surface of objects. While this may allow a layperson to grasp the concept of infrared equipment operation, it can foster a basic misunderstanding that can lead to significant diagnostic errors.

Infrared imagers do not sense temperature. Rather, they directly sense infrared energy radiated from the surface of an object. Using sophisticated on-board computers, radiant energy is converted to a monochrome or multi-colored image that represents the apparent thermal patterns across an object’s surface.

Emissivity is the most significant characteristic influencing the amount of energy radiated by an object. Emissivity is a dynamic phenomenon that is influenced by many factors; the relative amount of energy radiated by an object is described by its emittance.

Emittance is a number between 0 and 1 that numerically expresses how well an object radiates infrared energy when compared to a blackbody at the same wavelength and temperature. The emittance of an object will vary with temperature, shape and surface condition. In thermography, emittance can be further influenced by viewing angle and the spectral response of the imager/radiometer utilized.

In order to ensure accuracy, it is imperative for a thermographer to understand the concepts of radiance and the principles of non-contact temperature measurement. Anything that affects emissivity will influence both qualitative and quantitative data.

For over 35 years, Infraspection Institute’s Certified Infrared Thermographer^® training courses have set the industry standard for excellence. Our Certified Infrared Thermographer^® and applications courses combine infrared theory with practical, real-world approaches that enable students to quickly master skill sets that help to ensure accuracy. All courses are taught by field-experienced practicing thermographers. For more information or to register for a class, call 609-239-4788 or visit us online at www.infraspection.com.