Patent ID: 8255172

Claim:
A method for analyzing an object bearing a repeating pattern suffering from random defects which it is desired to find using a first sensitivity and first false alarm rate and from repeater defects which it is desired to find at a second sensitivity higher than said first sensitivity and second false alarm rate, the method comprising: performing a single scan of at least a portion of interest within an object; using a first defect detection path to detect a first set of defects in the object thereby to generate a first defect map comprising a first plurality of defect locations; and using a second weaker defect detection path to detect a second set of defects in the object thereby to generate a second defect map comprising a second plurality of defect locations and generating a specific map by extracting a specific class of defects from said second set of defects, thereby to find on said object, defects not falling within said specific class, using only a single scan and using said first sensitivity, and also to find on said object, defects falling within said specific class, using the same scan but using said second sensitivity.