Design of image acquisition for surface inspection

Since the design of an inspection system typically requires a lot of application-dependent work, the provision of systematic methods and tools to assist in the design process could significantly reduce the system development and installation time. With this in view, a step-by-step design procedure for image acquisition systems is suggested, consisting of measurements of certain important optical parameters for the surfaces to be inspected, modelling of the measurements and arrangement of the imaging in a form that a computer can understand, simulation of the imaging process in a computer using optical analysis tools, and verification of the results through a pilot system. The procedure is exemplified by describing its application to the design of a steel sheet inspection system and its capacity for optimising the detection of various defects is demonstrated. For comparison, measurements made on some other materials are shown and the implications discussed. The results of the simulation and the pilot system for steel are compared and the usefulness of the computer-based design method is evaluated