INTEFEROMETRIC IMAGING SYSTEM

A quality control system provides for real-time, high-speed, high-resolution, comparison of the three-dimensional form of a sample with that of an examplar. The quality inspection system includes a sample analyzer, an exemplar analyzer, a comparator, a controller and a position memory. The sample analyzer includes a sample imager for providing an interferometric image of a sample of inspection, a sample scanner for scanning the sample image, and a sample transducer for converting the resulting sample scan into a sample signal representing the three-dimensional form of the sample. The exemplar analyzer similarly includes an exemplar imager, an exemplar scanner and an exemplar transducer to provide an exemplar signal representing an exemplary three-dimensional form for said sample. The comparator provides a comparison signal which identifies the scan times during which differences between the sample signal and the exemplar signal are detected. These signal differences correspond to differences in the fringe patterns of the interferometric sample and exemplar images and thus in form discrepancies in the sample from the exemplar. The comparison signal is used to enable writes to a memory which is constantly receiving position data at its data port so that position data corresponding to signal differences are stored. The position memory can then be read by a host system which can thus acquire a list of locations of potential defects.