The wafer scanning system includes imaging acquisition optics to reduce effective spot size. The smaller spot size reduces the number of photons scattered by the surface in proportion to the area of the spot. Air scattering is also reduced. The TDI is used to generate a wafer image based on a plurality of image signals integrated in a linear motion direction of the wafer. The illumination system floods the wafer with light, and the task of creating the spot is assigned to the imaging collection optics.
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