While interference fringes can occasionally be useful, they create problems when one is doing quantitative calculations on polymers such as can coatings. Also, the fringes can interfere in computer search systems.
V. T. Teng and W. H. Shumaker, "A Technique for Eliminating Interference Fringes from Infrared Spectra of Thin Polymer Films," Appl. Spectrosc. 40, 421-422 (1986)