Thermal imaging


The infrared radiation emitted by a machine or structure may be measured and analysed in order to gain information relating to its condition. Two main methods may be used.

The first is to examine the infrared energy emitted from an object under normal operating conditions. Regular or continuous monitoring will readily identify changes in infrared emissions which may be associated with physical changes to the object. Possible applications are wide and varied: a hot spot on a machine casing may indicate a bearing that is about to fail whereas a cold spot on a building may indicate water ingress.

The second method finds its main application in the testing of composite materials and aerospace components. A heat source, often a Xenon flash tube, is used to raise the surface temperature of the object under test. The temperature rise need not be more than 0.01°K but must be rapid. Abnormalities within the structure affect the rate at which heat is dissipated onto the body of the material and will be clearly identified using thermographic imaging equipment. Typical applications would be the detection of disbonds in honeycomb panels used in the aerospace industry.