Thermography or Thermal imaging or radiometric imaging is a non-destructive testing (NDT) technique which is used to obtain thermal images of objects, in order to detect any sub-surface anomalies (in the form of ‘hot spots’) and temperature distribution on the surface of any material. The thermal images produced by a thermal imaging camera are known as ‘thermograms’, and these are colourful images which depict the distribution of temperature on the surface of a test object. Such a distribution of temperature is indicative of the difference in temperature over a particular surface area, which is a function of the variations in the flow of heat in the same region. As a result, hotter regions appear differently coloured than colder regions. The main advantageous difference between this technique & the other NDT methods is the fact that it is a non-contact as well as a non-invasive technique of testing. Thermography is one of the fastest growing NDT techniques because of its widespread popularity and its broad scope of applications. It finds substantial use in military, industrial, medical, electrical, and construction-related applications. Our team of experienced & certified engineers at Spectro Analytical Labs Ltd. is extremely adept at providing the right & meaningful test results along-with corresponding interpretations (which is vital) for any project that is to be carried out.
What are Infrared rays?
Infrared light is a substantial part or portion of the electromagnetic spectrum, and extends beyond the nominal red edge of the visible spectrum at 740 nm to 300 μm (or 300000 nm). It lies between the visible & the microwave region of the electromagnetic spectrum. Although human beings cannot detect IR light but they can realize it quite well. As per a scientific study, the nerve endings in human skin respond to temperature changes as small as 0.009 °C
(0.0162 °F). This region of the spectrum can be divided into 3 sub-regions: near infrared (0.78 to 3 μm), mid infrared (3 to 50 μm), & far-infrared (50 to 1000 μm). The IR light is associated with the vibrational motion of molecules. The region from 8 to 15 μm is referred to as the ‘thermal imaging’ or ‘thermal infrared’ region, & is considered to be the optimum region for taking thermal images. The thermal imaging devices work best in this region. The credit of discovering IR radiation (in 1800) goes to a German astronomer Sir Frederick William Herschel, who measured the temperature differences of the spectrum created by making sunlight to pass through a prism & then based upon his observations concluded that the region beyond the red light marks the beginning of IR spectrum.
Working of a Thermal Imaging Camera
Infrared thermography involves transforming or converting an infrared image into a radiometric one, and then the temperature values can be read from the image. The infrared radiation or energy coming from a test object is captured by an IR detector after being focused by the optics. The information from the detector is then sent to the sensor electronic system for image processing. Finally, the data from the detectors get translated into an image which can be viewed in the viewfinder or on a standard video monitor.
Applications of Thermography
Thermographic method of testing finds use in a number of industrial & other commercial applications like monitoring of high voltage power lines, internal fuse damage, damaged insulation, steam trap, corroded connections in electrical panel, overheated motor, water loss or leakage through ceilings, energy loss in buildings, damage in concrete, buildings & other constructions etc. Such monitoring facilities help in predicting failure of key components & also of entire systems in important machineries.