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Previous studies have shown that nanometer scale defects can lead to the formation of submicrometer craters, if located in coatings with a relatively small thickness. Due to the small size, such damages are challenging to detect in the online and offline damage detection and may therefore lead to an overestimation of the LIDT for the tested optical component. However, the influence of these nanopits on the optical properties and the impact on the initiation of catastrophic damage was not investigated in detail in the past. In order to study the correlation between nanopits, optical properties and catastrophic damage, samples with an AR-coating were fabricated by means of ion beam sputtering (IBS) and tested for their laser resistance by LIDT raster scans in the nanosecond regime at 355 nm. The generation and morphology changes of the nanopits were monitored for different pulse numbers and in dependence of the starting fluence. In addition to the inspection with an optical microscope in differential interference contrast (DIC) mode as prescribed by ISO 21254, alternative inspection methods, for example, dark field microscopy and scanning electron microscopy (SEM), were used to detect the nanopits. The damage test revealed that nanopits occur rarely in standard AR-coatings and possess only a small relevance for the LIDT. The typical damage morphology observed consisted of micrometer-sized pits which exhibited a stable size over a large fluence range and no growth after repeated irradiation. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

Investigating the properties of manufactured polymer optical fibers is essential to determine proper areas of application. Using pulsed laser radiation, especially with respect to laser activity in optical fibers, the maximum acceptable transmittable energy without inducing damage is of particular interest. Therefore, this work is related to laser-induced damage in polymer optical fibers at a wavelength of 532 nm and a pulse duration of 7.3 ns. In particular, the influence of the coupling condition on the transmittable pulse energy and the damage behavior applying an R-on-1 test procedure are analyzed in this study. The obtained results give information about the long-Term behavior and will be used to optimize the manufacturing process. © COPYRIGHT SPIE

Based on the z-scan method, an interferometric set-up for measuring the optical Kerr-effect was engineered and optimized. Utilizing a Mach-Zehnder configuration, the wave front deformation caused by the Kerr induced selffocusing is monitored. Fitting this deformation to a theoretical approach basing on a beam propagation model, the nonlinear refractive index is obtained. The procedure can be applied to measure the nonlinear refractive index of both, the substrate material as well as the deposited dielectric layer on top of the substrate. The nonlinear refractive index of a layer specially deposited for this purpose as well as for several substrate materials was measured and the results presented. © 2017 SPIE.

The exploitation of nonlinear effects in multi-layer thin films allows for optics with novel functions, such as all-optical switching and frequency conversion. In this contribution, an improved interferometric setup for the measurement of the nonlinear refractive index in dielectric substrates and deposited single layers is presented. The setup is based on the wave front deformation caused by the self-focusing in the measured samples. Additionally, measurement results for a highly nonlinear material, indium-Tin-oxide (ITO) are presented with respect to the materials power handling capabilities and compared to values from other materials. © COPYRIGHT SPIE

In many advanced fields of optical technology, progresses are extremely dependent on reliable characterization procedures employed for quality assessment in volume manufacturing as well as for the optimization of high performance optical components. With the rapid development of laser technology and modern optics, especially optical metrology gained of importance for the quality management in the industrial production environment and also for research in optical components. Besides absorption and scatter losses, the spectral characteristics and laser induced damage thresholds are considered nowadays as common quality factors, which are often indicated in optics catalogues and are considered by the customers for the design of optical systems. As a consequence of this trend, standardization of measurement procedures for the characterization of optical components became a crucial point for the optics industry and for critical applications of optical components in laser systems as well as conventional optical devices. During the last decade, adapted standard measurement techniques have been elaborated and discussed in the Technical Committee ISO/TC 172 of the International Organization for Standardization (ISO) resulting in practical International Standards or Draft Standards for the measurement of optical absorption, scattering, reflectance and laser induced damage thresholds. In this paper, the current state of standardized characterization techniques for optical components is summarized. Selected standards for the measurement of absorption (ISO 11551), scattering (ISO/DIS 13696) and laser induced damage thresholds (ISO/DIS 11254, Parts 1 and 2) will be described and discussed in view of recent trends in laser technology and its applications in semiconductor lithography.

Particles, which contaminate the substrate during thin film deposition, are prone to cause irremovable defects and demand special attention in the field of high precision laser optics as they can lead to localized absorption and laser damage. In this contribution, we present a camera based fully in-vacuum device which continuously monitors the coating surface of a transparent test substrate under dark field illumination. We show the possibilities of this setup regarding the sensitivity to small particles (diameter 1 μm). As the first operational test of the particle monitor, singe layers of HfO 2 are grown on fused silica. By analyzing the evolution of the scattering intensity of the particles, we derive their position in the substrate-coating-system. Therefore, this in situ particle detection concept can deliver data on which process step is responsible for particle generation in multilayer films and aims to be a tool to minimize coating defects. © COPYRIGHT SPIE.