Automated visual inspection(AVI) capability has become an important key component in the automated manufacturing system. An intensity(or color) image of a scene is quickly affected by optical property of object, condition and roughness of surface, lens and filters, image sensor property and lighting system. Generally visual system has noise and has to process the numerous data. For fast cheap AVI system it is important to get the good image quality which result from careful attention to the design of the lighting system.
In this paper we design the lighting subsystem of AVI system for printed circuit board(PCB) pattern inspection. We obtain the reflection property of objects by experiments which measure intensity with varying the viewing direction of image sensor and the lighting direction of illuminator. We measure the spectral reflectance of objects for choosing the light source. We measure the uniformity of ring-type illuminator with varing the diameter of illuminator and the distance between object and illuminator. We design the lighting system from the experimental results. The results show that we can obtain the good image quality.
