Light Scattering Spectroscopy (LiSSP) - LiSSP is an optical technique for measuring the power spectral density of the surface morphology during growth or sputter-etching.  By using a broad-band light source and a solid-state spectrometer, the full spectrum of scattered light is measured during processing without having to move the sample, the source or the detector.  LiSSP has been applied to the kinetics of island growth and self assembly in SiGe/Si (001) and to the formation and decay of sputter-induced ripples.  A schematic of the LiSSp technique and an example of a measurement are shown in figure 3.  The data were obtained from the array of SiGe islands shown in the AFM image.  The peak in the light scattering spectrum corresponds to the average spacing between the islands which can be used to determine the island volume