APPLICATION AND COMPARISON OF ALGORITHMS FOR THE EVALUATION OF INTERFEROGRAMS .3. ESTIMATION OF REFRACTIVE-INDEX CHANGES IN POLYMER-FILMS INDUCED BY INTERACTION WITH ORGANIC-SOLVENT MOLECULES

Organic molecules are easily absorbed by polymers. This interaction in duces changes in the volume and the refractive index of the resulting mixture phase. The change in the bulk refractive index is directly rel ated to the volume fraction of the organic substance in the resulting mixture, It is essential for an understanding of the underlying phenom ena to study the change in volume and the change in refractive index s eparately. A novel method is presented to separate both effects by whi te light interferometric measurements on thin polymer films. This meth od is based on a spectral fitting of amplitude and phase shift effects in the interferograms.