The standard method for assessing the structural quality of epitaxially grown semiconductor films is cross-sectional transmission electron microscopy (XTEM). XTEM, however, is a slow, labour-intensive and destructive technique. In this work we show that fast and non-destructive optical measurements can be used instead of XTEM for the assessment of the structural quality of polycrystalline silicon films epitaxially grown on seeded glass substrates. The seed layers are prepared by aluminium-induced crystallization and the epitaxial thickening is performed using ion-assisted deposition. The optical methods used are optical transmission microscopy, selected-area Raman spectroscopy. and UV reflectance measurements. XTEM images are also taken for comparison and are shown to fully support the findings from the optical measurements. (C) 2004 Elsevier B.V. All rights reserved.