The presence of shallow interfaces in the crater bottom surface can lead to the appearance of several reflected beams from different depths that can distort the calibration close to these interfaces. A multi-beam scattering model has been developed. The results of this simulation are compared with experimental data and allow interpretation of the laser interferometer data for multilayer structures. Statistical analysis of data from different types of structures show that even with the presence of measurement artifacts, the laser interferometer can be used for improving the depth scale calibration accuracy. (C) 2004 Elsevier B.V. All rights reserved.