We propose a simple method to analyse the Burgers vector of dislocations in crystalline semiconductors or insulators by light scattering. The method is based on the analysis of cross-slip processes revealed by three-dimensional laser-scattering tomography. It permits the full analysis of the Burgers vector distribution in macroscopic volumes. Its application presupposes that (i) dislocations are decorated by precipitates and (ii) cross-slip took place in the sample. (C) 2008 Elsevier B.V. All rights reserved.