Mixed oxide coatings for optics.

Material mixtures offer new possibilities for synthesizing coating materials with tailored optical and mechanical properties. We present experimental results on mixtures of HfO2, ZrO2, and Al2O3, pursuing applications in UV coating technology, while the mixtures are prepared by magnetron sputtering, ion beam sputtering, plasma ion-assisted deposition (PIAD), and electron beam evaporation without assistance. The properties investigated include the refractive index, optical gap, thermal shift, and mechanical stress. The first high reflectors for UV applications have been deposited by PIAD.

Optical characterization of hybrid antireflective coatings using spectrophotometric and ellipsometric measurements.

A hybrid antireflective coating combining homogeneous layers and linear gradient refractive index layers has been deposited using different techniques. The samples were analyzed optically based on spectrophotometric and spectroscopic ellipsometry measurements under different angles of incidence in order to precisely characterize the coatings. The Lorentz-Lorenz model has been used to calculate the refractive index of material mixtures in gradient and constant index layers of the coating. The obtained refractive index profiles have been compared with the targeted ones to detect errors in processes of deposition.

Optical broadband monitoring of conventional and ion processes.

This contribution is focused on applications of spectroscopic methods for the precise control of deposition processes. Besides a monochromator system with a moving grating for the deep ultraviolet/vacuum ultraviolet (DUV/VUV) spectral range, two approaches are presented for online spectrophotometers with CCD arrays. The conventional spectrophotometer is considered for the operator-assisted deposition of fluoride coatings applied in the DUV/VUV range. The concepts with CCD arrays are combined with an advanced software tool for an automatic production of optical coatings. An ion-assisted deposition process and ion-beam sputtering are considered for rapid manufacturing of complex layer systems in the visible and near-infrared spectral ranges. The present contribution summarizes and discusses the major aspects of the described combinations.

Application of optical broadband monitoring to quasi-rugate filters by ion-beam sputtering.

Methods for the manufacture of rugate filters by the ion-beam-sputtering process are presented. The first approach gives an example of a digitized version of a continuous-layer notch filter. This method allows the comparison of the basic theory of interference coatings containing thin layers with practical results. For the other methods, a movable zone target is employed to fabricate graded and gradual rugate filters. The examples demonstrate the potential of broadband optical monitoring in conjunction with the ion-beam-sputtering process. First-characterization results indicate that these types of filter may exhibit higher laser-induced damage-threshold values than those of classical filters.