Wilbrandt, S.S.WilbrandtStenzel, O.O.StenzelGäbler, D.D.GäblerKaiser, N.N.Kaiser2022-03-032022-03-032005https://publica.fraunhofer.de/handle/publica/208269Reengineering the refractive index profile of inhomogeneous coatings is a troublesome task. Multiplicity of solutions may significantly reduced by providing additional information. For this reason an in-situ broadband monitoring system was developed to measure the transmittance of the growing film directly at the rotating substrate. For characterization of these coatings a new model was developed, which significantly reduces the number of parameters. The refractive index profile may be described by a proper number of equally spaced volume fraction values using the Bruggeman effective media approach. A good initial approximation of the refractive index profile can be generated based an deposition rates for both materials recorded with quartz crystals monitor during manufacturing. During the optimisation process, a second order minimization algorithm was used to vary the refractive index profile of the whole coating and film thickness of the intermediate stages. Finally, a significantly improved accuracy of the modelled transmittance was achievedeninhomogeneous coatinghybrid algorithmbroadband monitoringrefractive index profile620681journal article