Lighting configuration for metrology system with images acquired at different focus positions

Abstract

A lighting configuration is provided for utilization with a metrology system. The metrology system includes a camera that provides images of a workpiece at different focus positions (e.g., through operation of a variable focal length lens). The lighting configuration includes a plurality of lighting portions which illuminate the workpiece for the imaging. The lighting portions are distributed in an arrangement (e.g., an annular arrangement) in which an imaging lens portion of each lighting portion directs light toward a central volume (e.g., for which illumination in the central volume may be relatively uniform in X, Y and Z axis directions). Each imaging lens portion may include at least two lenses in a telecentric arrangement. Each lighting portion may comprise an optical homogenizer. The camera acquires a stack of images of the workpiece, from which focus curve data may be determined which indicates 3 dimensional positions of surface points on the workpiece.