@inproceedings{VerpoortWittrock2011,
  author    = {Verpoort, Sven and Wittrock, Ulrich},
  title     = {Deformable mirrors for high power lasers},
  series = {Proceedings of the 8th International Workshop on Adaptive Optics for Industry and Medicine (AOIM)},
  booktitle = {Proceedings of the 8th International Workshop on Adaptive Optics for Industry and Medicine (AOIM)},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-106953},
  year      = {2011},
  abstract  = {It has been shown that the beam quality and the efficiency of high-power solid-state lasers could be enhanced by the use of deformable mirrors in order to compensate for optical aberrations. An intracavity compensation requires a deformable mirror which is capable of handling very high laser intensities. The active diameter of the deformable mirror should be a few millimeters in order to match typical fundamental mode laser beam diameters. There is a wide variety of commercially available deformable mirrors, but neither meets all requirements.},
  language  = {en}
}
@article{AlbersWittrock2011,
  author    = {Albers, Klaus and Wittrock, Ulrich},
  title     = {Optical pump concepts for highly efficient quasi-three-level lasers},
  series = {Appl. Phys. B},
  volume    = {105},
  journal   = {Appl. Phys. B},
  publisher = {Springer},
  doi       = {10.25974/fhms-646},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-6467},
  pages     = {245 -- 254},
  year      = {2011},
  abstract  = {Efficient quasi-three-level laser operation requires the generation of the highest possible pump rate from a given pump source. We derive the fundamental scaling laws for the pump rate and we extract optimization criteria for pump concepts from these laws. The analysis is then applied to the thin-disk laser. Based on the results, a novel pump concept for thin-disk lasers is proposed, which allows for several tens of pump beam passes and reduces the optical complexity of conventional pump concepts. Furthermore, the beam quality of the pump source is preserved almost completely, facilitating the highest possible pump rate.},
  language  = {en}
}
@inproceedings{VerpoortWittrock2011,
  author    = {Verpoort, Sven and Wittrock, Ulrich},
  title     = {Novel unimorph deformable mirror with monolithic tip-tilt functionality for solid state lasers},
  series = {MEMS Adaptive Optics V, Proc. SPIE},
  volume    = {7931},
  booktitle = {MEMS Adaptive Optics V, Proc. SPIE},
  publisher = {SPIE},
  doi       = {10.25974/fhms-647},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-6471},
  pages     = {793107},
  year      = {2011},
  abstract  = {We present a new type of unimorph deformable mirror with monolithic tip-tilt functionality. The tip-tilt actuation is based on a spiral arm design. The mirror will be used in high-power laser resonators for real-time intracavity phase control. The additional tip-tilt correction with a stroke up to 6 μm simplifies the resonator alignment significantly. The mirror is optimized for a laser beam footprint of about 10 mm. We have modeled and optimized this mirror by finite element calculations and we will present design criteria and tradeoffs for this mirrors. The mirror is manufactured from a super-polished glass substrate with very low surface scattering and excellent dielectric coating.},
  language  = {en}
}
@misc{OPUS4-4711,
  title     = {6th Laser Ceramics Symposium},
  series = {Opt. Mat.},
  volume    = {34},
  journal   = {Opt. Mat.},
  editor    = {Wittrock, Ulrich and Kynast, Ulrich and J{\"u}stel, Thomas and Bredol, Michael},
  publisher = {Elsevier B.V.},
  pages     = {935 -- 1002},
  year      = {2012},
  language  = {mul}
}
@inproceedings{VerpoortRauschWittrock2012,
  author    = {Verpoort, Sven and Rausch, Peter and Wittrock, Ulrich},
  title     = {Novel unimorph deformable mirror for space applications},
  series = {International Conference on Space Optics (ICSO), Proc. SPIE},
  volume    = {10564},
  booktitle = {International Conference on Space Optics (ICSO), Proc. SPIE},
  publisher = {SPIE},
  doi       = {10.25974/fhms-651},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-6516},
  pages     = {1056414-1},
  year      = {2012},
  abstract  = {We have developed a new type of unimorph deformable mirror, designed to correct for low-order Zernike modes. The mirror has a clear optical aperture of 50 mm combined with large peak-to-valley Zernike amplitudes of up to 35 μm. Newly developed fabrication processes allow the use of prefabricated super-polished and coated glass substrates. The mirror's unique features suggest the use in several stronomical applications like the precompensation of atmospheric aberrations seen by laser beacons and the use in woofer-tweeter systems. Additionally, the design enables an efficient correction of the inevitable wavefront error imposed by the floppy structure of primary mirrors in future large space-based telescopes. We have modeled the mirror by using analytical as well as finite element models. We will present design, key features and manufacturing steps of the deformable mirror.},
  language  = {en}
}
@inproceedings{RauschVerpoortWittrock2012,
  author    = {Rausch, Peter and Verpoort, Sven and Wittrock, Ulrich},
  title     = {Novel unimorph adaptive mirrors for astronomy applications},
  series = {Proc. SPIE 8447, Adaptive Optics Systems III, 844764},
  booktitle = {Proc. SPIE 8447, Adaptive Optics Systems III, 844764},
  publisher = {SPIE},
  doi       = {10.25974/fhms-620},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-6203},
  year      = {2012},
  abstract  = {We have developed a new type of unimorph deformable mirror for the correction of low-order Zernike modes. The mirror features a clear aperture of 50 mm combined with large peak-to-valley amplitudes of up to 35 μm. Newly developed fabrication processes allow the use of prefabricated, coated, super-polished glass substrates. The mirror's unique features suggest the use in several astronomical applications like the compensation of atmospheric aberrations seen by laser beacons, low light astronomy, and the use in woofer-tweeter systems. Additionally, the design enables an efficient correction of the inevitable wave-front error imposed by the floppy structure of primary mirrors in future large space telescopes. We have modeled the mirror by using analytical as well as finite element models. We will present design, key features and manufacturing steps of the deformable mirror.},
  language  = {en}
}
@inproceedings{RauschVerpoortWittrock2012,
  author    = {Rausch, Peter and Verpoort, Sven and Wittrock, Ulrich},
  title     = {Characterization of a miniaturized unimorph deformable mirror for high power cw-solid state lasers},
  series = {Proc. SPIE 8253, MEMS Adaptive Optics VI, 825309},
  booktitle = {Proc. SPIE 8253, MEMS Adaptive Optics VI, 825309},
  publisher = {SPIE},
  doi       = {10.25974/fhms-622},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-6226},
  year      = {2012},
  abstract  = {We have developed a new type of unimorph deformable mirror for real-time intra-cavity phase control of high power cw-lasers. The approach is innovative in its combination of super-polished and pre-coated highly reflective substrates, the miniaturization of the unimorph principle, and the integration of a monolithic tip/tilt functionality. Despite the small optical aperture of only 9 mm diameter, the mirror is able to produce a stroke of several microns for low order Zernike modes, paired with a residual static root-mean-square aberration of less than 0.04 µm. In this paper, the characteristics of the mirror such as the influence functions, the dynamic behavior, and the power handling capability are reported. The mirror was subjected to a maximum of 490 W of laser-light at a wavelength of 1030 nm. Due to the high reflectivity of over 99.998 percent the mirror is able to withstand intensities up to 1.5 MW/cm2.},
  language  = {en}
}
@article{PerchermeierWittrock2013,
  author    = {Perchermeier, Julian and Wittrock, Ulrich},
  title     = {Precise measurements of the thermo-optical aberrations of an Yb:YAG thin-disk laser},
  series = {Opt. Lett.},
  volume    = {38},
  journal   = {Opt. Lett.},
  publisher = {OSA},
  doi       = {10.25974/fhms-685},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-6854},
  pages     = {2422 -- 2424},
  year      = {2013},
  abstract  = {We report on interferometric measurements of the thermo-optical aberrations of the laser medium of an Yb:YAG thin-disk laser in pumped and cw lasing conditions at several pump-power levels with a mean repeatability of 5 nm. These measurements build the basis for future intracavity compensation of the aberrations with our deformable mirror in order to improve the fundamental-mode efficiency.},
  language  = {en}
}
@article{Wittrock2014,
  author    = {Wittrock, Ulrich},
  title     = {Grenzen? Welche Grenzen? Prof. Ulrich Wittrock, Leiter des Labors f{\"u}r Photonik an der Fachhochschule M{\"u}nster, fragt nach den ultimativen Grenzen der Lasertechnik},
  series = {Laser Community - das Lasermagazin von Trumpf},
  volume    = {02:14},
  journal   = {Laser Community - das Lasermagazin von Trumpf},
  year      = {2014},
  language  = {de}
}
@article{Wittrock2014,
  author    = {Wittrock, Ulrich},
  title     = {Limitations? What Limitations? Prof. Ulrich Wittrock, head of the Photonics Laboratory at the M{\"u}nster University of Applied Sciences, seeks out the ultimate boundaries of laser technology},
  series = {Laser Community - the laser magazine from Trumpf},
  volume    = {02:14},
  journal   = {Laser Community - the laser magazine from Trumpf},
  year      = {2014},
  language  = {en}
}