A high-sensitivity, one-sided x-ray inspection system

This paper describes an x-ray backscatter inspection system capable of probing a sample from one side to detect discontinuities such as delaminations, voids, cracks or foreign material. The method makes use of a new backscatter x-ray concept. An x-ray camera with a slot collimator (instead of pin-holes as in past cameras) offers much improved speed of response for imaging scattered radiation. The collimation of the interrogating x-ray beam and the field of view of the imaging camera provide a means to locate a defect and size it. The technique is particularly useful for the inspection of laminated, composite structure as used in pressure vessels, rocket motor cases, aircraft structure, etc. The primary components of the inspection system are an x-ray source providing a collimated x-ray beam and the slot camera. The initial studies to show the feasibility of the imaging technique, as reported here, have been done with x-ray film. The work has demonstrated that the x-ray backscatter instrument will detect anomalies quickly, effectively and in a quantitative manner. Further, as compared to other nondestructive testing approaches, the x-ray slot camera provides a one-sided, practical inspection of the total thickness of the inspected wall in a single view. The technique gives information which is, in effect, a backscatter tomograph. The presentation of the discontinuity indications in the total wall thickness of the object as given by the slot camera not only speeds the inspection but also enhances the interpretation of the inspection data