Disclosed is the use of a focused electromagnetic beam which is caused to impinge on the top surface of a tube shaped sample, to investigate a film coating on its inner surface during fabrication thereof and/or thereafter....http://www.google.com/patents/US7768660?utm_source=gb-gplus-sharePatent US7768660 - Non-destructive approach to ellipsometric monitoring of a film coating on the inner surface of a tube shaped sample
