Re-engineering of inhomogeneous coatings based on in-situ optical broadband monitoring data

S. Wilbrandt; O. Stenzel; D. Gäbler; N. Kaiser

doi:10.1117/12.624818

4 October 2005 Re-engineering of inhomogeneous coatings based on in-situ optical broadband monitoring data

S. Wilbrandt, O. Stenzel, D. Gäbler, N. Kaiser

Proceedings Volume 5963, Advances in Optical Thin Films II; 59630F (2005) https://doi.org/10.1117/12.624818
Event: Optical Systems Design 2005, 2005, Jena, Germany

Abstract

Inhomogeneous layers, such as so-called gradient index layers and rugate filters represent new and prospective thin film designs. Manufacturing such systems in practice requires calculation, deposition, monitoring and characterization of optical coatings with a well-defined continuous refractive index profile along an axis that is perpendicular to the film surface. Those coatings may be manufactured in the Leybold Syrus Pro 1100 deposition system by co-evaporation of SiO₂ and Nb₂O₅ as a sequence of several refractive index gradients. During these experiments our in-situ broadband monitoring system was used to measure the transmittance of the growing film directly at the rotating substrate. This additional information on the intermediate stages of the not yet completed film are extremely helpful in reverse engineering tasks, and clearly superior to the extent of information that may be drawn from the spectra of the completed film only. For characterization of these coatings a new model was developed, which significantly reduces the number of parameters. To generate a feasible parameter set, deposition rates for both materials recorded with quartz crystals monitor during deposition were used. This approach achieves a better accordance between in-situ measured transmittance and modelled transmittance than the intended design. During the optimisation process, a local 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 achieved.

Citation Download Citation

S. Wilbrandt, O. Stenzel, D. Gäbler, and N. Kaiser "Re-engineering of inhomogeneous coatings based on in-situ optical broadband monitoring data", Proc. SPIE 5963, Advances in Optical Thin Films II, 59630F (4 October 2005); https://doi.org/10.1117/12.624818

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