This invention relates in general to the inspection of surfaces to detect anomalies, and in particular, to an improved system that illuminates the surface inspected at the plurality of spots simultaneously for anomaly detection.
Conventional optical inspection methods employing scanning techniques typically causes a single spot on the surface inspected to be illuminated where the spot is scanned over the entire surface for anomaly detection. For improved signal-to-noise ratio caused by background scattering, the size of the illuminated spot has been continually reduced. This means that the amount of time required for the spot to scan over the entire surface is increased which is undesirable.
One solution to the above dilemma is proposed in U.S. Pat. No. 6,208,411, which is incorporated herein by reference in its entirety. This patent proposes a massively parallel inspection and imaging system which illuminates the surface at a plurality of spots where scattered light from the spots are imaged onto corresponding detectors in a detector array.
While the system in U.S. Pat. No. 6,208,411 provides a major enhancement in the total inspection throughput, it may be further improved for enhanced performance in certain applications. It is, therefore, desirable to provide an improved multi-spot inspection and imaging system with enhanced characteristics.