COMPTON X-RAY BACKSCATTER DEPTH PROFILOMETRY FOR AIRCRAFT CORROSION INSPECTION

A new technique for detecting and measuring second-layer corrosion and metal loss in aircraft using Compton backscattered X-rays is presente d. This technique gives a cross-sectional (through the thickness) view of aircraft sheet metal lay-ups and joints. It allows micrometer-accu racy dimensional measurements to be made as well as material identific ation of sub-surface (second) layers. This technique requires access t o only one side of the structure; it is not a transmission (shadow cas ting) technique. Measurement accuracy to 0.025 mm (0.001 in.) has been demonstrated. Relative to other X-ray techniques, this depth profilin g technique generates little ambient x-radiation. Hangar activities ca n continue uninterrupted in the vicinity of its use.