1. An optical scanning system for detection of anomalies, such as particles or pattern defects, on a surface comprising: means for directing a focused beam of light onto a sample surface to produce an illuminated spot thereon; means for scanning the spot across the surface along a first scan line; a first detector positioned adjacent to said surface to collect scattered light from the spot, wherein the detector includes a linear or two-dimensional array of sensors; and means for focusing scattered light from the illuminated spot at each of a plurality of positions along the scan line onto a corresponding sensor in the array.