Damage depth profiles have been investigated by spectroscopic ellipsometry (SE) using an improved optical model for the evaluation. Damage created by ion implantation of Ar+ ions into single crystalline silicon was characterized using SE and Rutherford backscattering spectrometry (RBS). To create buried disorder, Ar+ ions with an energy of 100 keV were implanted into the samples. Ion doses of 4.65×1014cm -2 and 6.75×1014cm-2 were used. In our optical model, the damage profile is described by sublayers with thicknesses inversely proportional to the slope of the profile, in contrast to the earlier model having equal thicknesses. The thicknesses of the sublayers are automatically calculated from the four parameters of the coupled half-Gaussian profile, while the number of the layers are held constant. The improved fit quality and the results of measurements made by RBS and transmission electron microscopy basically supported the optical model of SE.