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Analysis of interface and volume inhomogenities in a multilayer system by light scattering methods

 
: Pichlmaier, S.; Hehl, K.; Schuhmann, U.; Duparre, A.; Gliech, S.

France, C.; Gee, A.E.:
Specification, production, and testing of optical components and systems
Bellingham, Wash.: SPIE, 1996 (Europto series)
ISBN: 0-8194-2160-X
pp.287-296
International Symposium on Optical Systems and Production <1996, Glasgow>
English
Conference Paper
Fraunhofer IOF ()
atomic force microscopy; Dünne optische Schicht; Lichtstreuung; light scattering; Oberflächenrauheit; optical thin films; Rasterkraftmikroskopie; surface roughness

Abstract
We investigated thin MgF2/LaF3- and LaF3/MgF2-layers on opaque glass with angle resolved light scattering to analyse the different scattering contributions. We already showed the possibility of separating the volume scattering from the interface contribution for a single MgF2-layer on BK7. In this work we concentrated on layers with thicknesses common for multilayer mirrors in the UV. The roughness of the interfaces was included in the calculations by the power spectral density (PSD) measured with the atomic force microscope (AFM). This has proven to be better than a Gaussian or exponential correlation function ansatz. In order to obtain as much information as possible we also investigated the uncoated substrates and the corresponding single layer systems. We found again that the investigated layers, which have columnar structure, showed generally non-neglegible volume scattering. Additionally crosscorrelation between the different interfaces must be taken into consideration.

: http://publica.fraunhofer.de/documents/PX-3827.html