Patent ID: 9103800
Filing Date: 2015-08-11
Classification: G01N,G06T,Y10T

Abstract:
1. A method for inspecting a surface of a workpiece for asymmetric defects, the method comprising: scanning an incident beam on the surface of the workpiece to impinge thereon to create reflected light, extending along a light channel axis in a front quartersphere, and scattered light, the incident beam and the light channel axis defining an incident plane, collecting the scattered light at a plurality of collectors disposed above the surface at defined locations such that scatter from asymmetric defects is collectable by at least one collector, defining a channel by identifying a selected set of the collectors that have collected the scatter, obtaining signals associated with each collector in the channel, individually filtering the signals associated with each collector in the channel to obtain filtered output associated with each collector in the channel, individually thresholding the filtered signals to obtain thresholded filtered signals associated with each collector in the channel, combining individually thresholded filtered signals into a combined signal, and processing the combined signals to obtain information about asymmetric defects.