Machine vision applications frequently require uniform or near-uniform illumination of the object being imaged. Optimizing the illumination uniformity requires a precise definition of the criterion to be optimized. Previous work has considered the smoothest possible illumination at the center of the field of illumination. In this paper, we find the lighting placement that maximizes the surface area within which the illumination is uniform to within some tolerance. This definition of optimality comes closer to what is desired in practice, since one generally wishes to illuminate objects having non-zero extents. Several different types of lighting are considered: area, line, point, and ring sources. Symmetry arguments are used to reduce the complexity of the analysis in many cases. Of particular interest is how to select a lighting design to optimize the illumination uniformity across regions that can be described by simple geometric models, such as circles, squares, rectangles, regular polygons, etc.
Keywords: illumination, machine vision