Optical system for detecting anomalies and/or features of surfaces

The surface inspection system is to apply a first ramp, and the illumination beam is also a sequence or a second illumination at the same time on the surface. The reflected or scattered radiation is preferably collected by the three collection channels detected by the corresponding detector array 3, but a different number of channels and a detector array may be used. One or both of the illumination beam is focused to a line on the surface to be scanned and each line is imaged on at least one detector of up to three or more detection and acquisition channels. The relative motion between the line and the line scan in a direction perpendicular to the surface is induced to thereby increase the throughput, while maintaining the high resolution and sensitivity. The same detection channel may be used by the scattered or reflected radiation from both illumination beams. The Fourier filter may be used to filter out the diffracted in one or more different spatial frequencies.