Harmonic expansion is a useful tool to analyze the CSL triple junction distribution in a randomly oriented polycrystalline aggregate. By using this approach, a general form of the CSL triple junction distribution could be derived. It makes it possible to calculate-in a very efficient way-the frequency of occurrence of various CSL triple junctions. The accuracy of calculation is confirmed by the estimated frequency for the Sigma1-Sigma1-Sigma1 junctions, which turns out to be in very good agreement with its theoretical value as derived from fully analytical calculation. (C) 2005 Springer Science + Business Media, Inc.