Patent ID: 6696679
Filing Date: 2004-02-24
Classification: G01N,G02B

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