The potential of nonlinear optical techniques for a rapid on-line and non-destructive inspection and characterization of silicon wafers is discussed. As an example, the in-situ detection of external stress on the wafer is reported, resulting from specific mounting conditions. As an outlook the problem of radially non-uniform growth of the silicon crystal when utilizing the Czochralski-growth method is addressed. A simple technique is proposed to discriminate those sections of the wafer which are ready for use in further applications from those which are not useable for proper device fabrication, thus enabling the selection of appropriate material from as-grown crystals.