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Thermography - Infrared Imaging - NDT Technique

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Thermography uses a camera containing large numbers of infrared sensors which can detect and measure small temperature differences. The image showing these differences can be downloaded to and displayed on a PC, normally as a colour or grey-scale map.

There are two basic types of thermography; passive thermography and active thermography.

In passive thermography, the camera is simply pointed at the test piece and from the thermal image a temperature map is constructed. Active thermography involves heating the surface of the object rapidly using an external heat source and observing how the temperature decays with time. Flaws in the material show up by variations in the temperature decay rate.

TWI Resources

TWI owns state-of-the-art systems of both types:

  • Passive thermography - Fluke Ti30 infrared camera
  • Passive thermography - Thermoteknix 307KS miniature thermal camera
  • Active thermography – Thermal Wave Imaging EchoTherm™ Pulsed Thermography (PT) system


  • Data collection system can record temperature changes with time
  • High-speed, portable, and non-contact
  • Ability to inspect large areas


  • Aerospace industry including sandwich panels, carbon/epoxy composites and delamination/impact damage
  • Automotive industry including composite structures, spot welds and adhesive bonds
  • Power industry including wind turbine blades, coating uniformity and delamination in composites

For more information about TWI's NDT services, please email

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