Until recently, active thermography was considered to be a qualitative adjunct to more familiar NDT methods such as ultrasound or radiography. Despite several attractive attributes-the process is noncontact, requires only single-side access to the test piece and is capable of inspecting curved as well as flat surfaces-deployment of thermography for NDT has been infrequent, limited to noncritical inspections performed by specialists. However, because of a new generation of inspection systems, thermography is becoming increasingly popular as a primary NDT method. In applications ranging from routine inspection of the leading edge of the NASA Space Shuttle to quality assurance in the manufacture of aircraft engine components, helicopter rotor blades and land-based turbine blades, thermography has been used as a stand-alone inspection method, often replacing ultrasound or radiography.