Mr. Thomas Frei Profile

Thomas Frei

at Evatec AG

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Author

Publications (2)

Proceedings Article | 18 December 2024 Presentation + Paper

Process development of Ta2O5-SiO2 quantized nanolaminates for the use of complex optical filter systems

Manuel Baertschi, Stephan Waldner, Fabian Steger, Thomas Frei, Silvia Schwyn Thoeny, Xavier Maeder, Daniel Schachtler, Christoph Sturzenegger

Proceedings Volume 13190, 1319006 (2024) https://doi.org/10.1117/12.3032939

KEYWORDS: Refractive index, Tantalum, Coating, Mirrors, Laser damage threshold, Electric fields, Thin film coatings, Magnetrons, Coating thickness, Absorption

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Proceedings Article | 28 September 2021 Presentation + Paper

Pre-production simulation of optical monitoring combining monochromatic and broadband monitoring strategies

Silvia Schwyn Thoeny, Daniel Schachtler, Stephan Waldner, Thomas Frei, Manuel Baertschi

Proceedings Volume 11872, 118720O (2021) https://doi.org/10.1117/12.2597085

KEYWORDS: Coating, Error analysis, Camera shutters, Optical simulations, Neodymium, Global system for mobile communications, Data processing, Tolerancing, Signal processing, Reflectivity

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Various types of optical monitoring systems are established in industry. They range from single wavelength, over monochromatic to broadband monitoring to calculate a monitoring signal, which allows to terminate each layer in a filter at the required thickness. State of the art monitoring systems offer the capability of monochromatic and broadband monitoring in a single device. With these technologies available, the question arises how to combine these monitoring strategies for a specific application in a way, which leads to accurate coating results with the least sensitivity to production errors and thus to the highest yield. To answer this question without the need to perform costly coating runs, we developed a software tool, which mimics all the monitoring features of Evatec’s GSM optical monitoring system. Additionally, the software is able to disturb the simulated ideal monitoring signal with errors such as detector noise, drifts, deviations in shutter delay times, etc. The values of these disturbances are specific to the deposition tool. They were determined based on the broadband spectra of actual coating runs. By starting a virtual coating run with defined disturbances, the thickness deviations expected with a selected strategy can be assessed and the development of thickness deviations during the run, i.e. error compensation and error accumulation can be simulated. Within the software, parameters for the termination of each layer can be varied individually and the effect on the coating result can be observed. In order to demonstrate the capability of this tool, a specific coating design was then selected. For this design various monitoring strategies were tested, broadband strategies with different wavelength ranges, monochromatic strategies varying wavelength assignment per layer but also mixed strategies of broadband and monochromatic monitoring. The most stable monitoring strategy resulting from these simulations was coated as well as some of the less promising candidates and their results were compared.

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