Ms. Stefanie Unland Profile

Stefanie Unland

at Laser Zentrum Hannover e.V.

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Author

Publications (7)

Proceedings Article | 12 July 2023 Open Access

Comparative study with high-quality, functionally coated Alexandrite crystals for spaceborne LIDAR applications

S. Unland, R. Kalms, P. Weßels, T. Böntgen, H. Mädebach, M. Hunnekuhl, D. Kracht, M. Lorrai, P. Lorrai, M. Hmidat, J. Butkus, L. Lukoševičius, J. Neumann

Proceedings Volume 12777, 127771W (2023) https://doi.org/10.1117/12.2689942

KEYWORDS: Crystals, Alexandrite lasers, Alexandrite, Laser damage threshold, Laser energy, Reproducibility, Manufacturing, Laser systems engineering, LIDAR, Pulsed laser operation

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Proceedings Article | 8 March 2023 Presentation + Paper

Environmental testing of high-quality Alexandrite crystals and coatings for space applications

S. Unland, R. Kalms, P. Weßels, T. Böntgen, H. Mädebach, M. Hunnekuhl, D. Kracht, M. Lorrai, P. Lorrai, M. Hmidat, J. Butkus, L. Lukoševičius, J. Neumann

Proceedings Volume 12399, 123990C (2023) https://doi.org/10.1117/12.2649641

KEYWORDS: Crystals, Alexandrite, Alexandrite lasers, Laser damage threshold, Optical testing, Laser irradiation, Optical transmission, Laser development

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Proceedings Article | 12 October 2021 Poster

Development of alexandrite laser crystal treatment prior to coating deposition for high power space applications

Laurynas Lukoševičius, Justinas Butkus, Peter Wessels, Stefanie Unland, Roland Kalms, Tammo Böntgen, Heinrich Mädebach, Silke Kramprich, Michael Hunnekuhl, Dietmar Kracht, Jörg Neumann, Mirco Lorrai, Pier Lorrai, Mahmoud Hmidat

Proceedings Volume 11910, 119101J (2021) https://doi.org/10.1117/12.2598660

KEYWORDS: Crystals, Laser crystals, Alexandrite lasers, Coating, Alexandrite, High power lasers, Space operations, Optical components, Laser development, Silica

Proceedings Article | 12 September 2021 Presentation

Development of alexandrite laser crystal treatment prior to coating deposition for high power space applications

Laurynas Lukoševičius, Justinas Butkus, Peter Wessels, Stefanie Unland, Roland Kalms, Istvan Balasa, Heinrich Mädebach, Silke Kramprich, Lars Jensen, Dietmar Kracht, Jörg Neumann, Mirco Lorrai, Mahmoud Hmidat, Pier Lorrai

Proceedings Volume 11872, 1187211 (2021) https://doi.org/10.1117/12.2600165

KEYWORDS: Laser crystals, Crystals, Alexandrite lasers, Coating, Alexandrite, High power lasers, Space operations, Optical components, Laser development, Silica

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Proceedings Article | 11 June 2021 Open Access

GALACTIC: high performance Alexandrite crystals and coatings for high power space applications

P. Weßels, S. Unland, R. Kalms, S. Spiekermann, I. Balasa, H. Mädebach, S. Kramprich, L. Jensen, D. Kracht, M. Lorrai, P. G. Lorrai, M. Hmidat, J. Butkus, L. Lukoševičius, J. Neumann

Proceedings Volume 11852, 118526S (2021) https://doi.org/10.1117/12.2600321

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Spaceborne Earth observation based on laser instruments provides new technologies to monitor the atmosphere or our planet’s surface. Space-qualified Alexandrite laser crystals show convincing properties as a laser-active medium in high power laser systems for space-based missions, e.g. the wavelength tunability and the excellent material properties, such as high thermal conductivity and a good breaking strength. Therefore, the Horizon 2020 project GALACTIC was initiated to realize space-qualified, high-quality coated Alexandrite crystals relying on a purely European-based supply chain. The project consortium will push the development of Alexandrite crystals and coatings within the EU from the current Technology Readiness Level (TRL) 4 up to TRL 6. The Horizon 2020 project GALACTIC, which will be presented, has been initiated to realize space qualified high quality, high performance coated Alexandrite crystals rest on a purely European-based supply chain. The project consortium, consisting of Optomaterials S.r.l., Altechna Coatings and the Laser Zentrum Hannover e.V., provides the necessary expertise in the fields of laser crystal growth, optical coatings and laser systems to push the development of high quality, high damage threshold Alexandrite coatings within the EU up to TRL 6. In order to reach the GALACTIC goals, different technology areas will be addressed. On the one hand, Optomaterials S.r.l. as an experienced optical crystal manufacturer will continuously refine the crystal growth process and improve the raw crystals as well as the cutting and polishing quality step-by-step. As an experienced company in optical coatings production for space applications, Altechna Coatings will secondly develop high quality, low loss, high damage threshold coatings specifically tailored for application onto Alexandrite laser crystals. The superior performance of the coated crystals will then be proven in demonstrator laser systems. The Laser Zentrum Hannover e.V. has the required knowledge to set up laser demonstrator prototypes, whose specifications mimic typical earth observation laser source requirements. Finally, the GALACTIC consortium will work closely together to characterize and qualify the developed coated laser crystals. By collaborating with the European space industry and deriving the detailed requirements from typical earth observation space missions, a detailed TRL 6 components test plan will prove the TRL 6 qualification of the developed coated laser crystals. This will conclude the development process and will enhance the European non-dependence status of the Alexandrite laser crystal market. At the conference, we will present the project and its consortium as well as detailed strategies to enable a non-dependence of Europe on coated Alexandrite laser crystal technology and enabling long term European availability of this technology. This project has received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No 870427.

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Proceedings Article | 5 March 2021 Poster + Presentation + Paper

GALACTIC: high performance alexandrite crystals and coatings for high power space applications

P. Weßels, S. Unland, R. Kalms, S. Spiekermann, I. Balasa, H. Mädebach, S. Kramprich, L. Jensen, D. Kracht, M. Lorrai, P. Lorrai, M. Hmidat, J. Butkus, L. Lukoševičius, J. Neumann

Proceedings Volume 11664, 1166411 (2021) https://doi.org/10.1117/12.2576180

KEYWORDS: Crystals, Laser crystals, Alexandrite lasers, Alexandrite, Space operations, Laser systems engineering, Laser applications, New and emerging technologies, Manufacturing, Laser development

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Proceedings Article | 11 September 2020 Poster + Presentation

Alexandrite laser crystal treatment and coatings for high LIDT space applications

Laurynas Lukoševičius, Peter Wessels, Stefanie Unland, Stefan Spiekermann, Istvan Balasa, Silke Kramprich, Lars Jensen, Dietmar Kracht, Jörg Neumann, Mirco Lorrai, Pier Giorgio Lorrai, Mahmoud Hmidat, Justinas Butkus

Proceedings Volume 11514, 115141Z (2020) https://doi.org/10.1117/12.2570169

KEYWORDS: Crystals, Laser crystals, Alexandrite lasers, Optical coatings, Laser systems engineering, Alexandrite, Optical components, Laser applications, Plasma etching, Crystal optics

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