A method for determining an in-focus position and a vision inspection system

摘要

The present invention relates to a method for determining a difference (Delta Z) between a sample position (Zobj) and an in-focus position (Zf), as well as a vision inspection system. In a first step image data depicting a sample (304a, 304b) is captured. Next, a feature set is extracted from the image data. Thereafter, the feature set is classified into a position difference value, corresponding to the difference between the sample position and the in-focus position, by using a machine learning algorithm that is trained to associate image data features to a position difference value.