Abstract: A method for focusing on disk-shaped objects with patterned and unpatterned surfaces includes imaging of the patterned and unpatterned surfaces on a disk-shaped object for defect detection and defect classification by using various preset values of a focus regulation system to acquire the image sequence. At least one preset value is learned on the basis of an image sequence at least at one position in a substantially flat reference region of the surface of the disk-shaped object. A regulated adjustment is provided of a measurable distance from a carrier plane to a reference plane, wherein the carrier plane serves as a support for the disk-shaped objects. The distance is adjusted by applying the at least one preset value, which is overlaid on the regulation system, a focus state is evaluated by an image processor according to at least one rule, and the at least one preset value is ascertained therefrom.

Abstract: The object of a method for detecting defects in the inspection of structured surfaces is to ensure a detection of defects which is not dependent on the number of structuring planes and includes structure features in real-time operation for separating defects from good structures. From image point classification in which zones of a recorded image which have similar image point features are assembled, a gray-value intermediate image containing edge structures and corner structures is generated from the image and the behavior of the image point features of every image point in the intermediate image is analyzed with respect to its neighboring image points. The method is used predominantly in statistical process control in the production process of masks, LCD's, printed circuit boards and semiconductor wafers.