Gerhard Borrmann (1908–2006) and Gerhard Hildebrandt (1922–2005): their life stories and their contribution to the revival of dynamical theory in the 1950's

G. Borrmann and his former student and co-worker G. Hildebrandt passed way a few months ago. Both have given major contributions to the development of the dynamical theory of diffraction and to X-ray imaging topography. Their career and their scientific achievements are reviewed briefly, with emphasis on Borrmann's very early work (Kossel lines, the discovery of anomalous absorption and of the Borrmann fan). (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)