@inproceedings{LeitzGerhardsVerpoortetal.2021,
  author    = {Leitz, Sinje and Gerhards, Maximilian and Verpoort, Sven and Wittrock, Ulrich and Freudling, Maximilian and Grzesik, Andreas and Erhard, Markus and Hallibert, Pascal},
  title     = {Vibration and shock testing of a 50 mm aperture unimorph deformable mirror},
  series = {Proceedings of the International Conference on Space Optics (ICSO)},
  volume    = {11852},
  booktitle = {Proceedings of the International Conference on Space Optics (ICSO)},
  organization    = {ESA/ESTEC, Noordwijk},
  doi       = {10.25974/fhms-13740},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-137401},
  pages     = {118524N},
  year      = {2021},
  abstract  = {We present our latest results on a refined unimorph deformable mirror which was developed in the frame of the ESA GSTP activity "Enabling Technologies for Piezo-Based Deformable Mirrors in Active Optics Correction Chains". The identified baseline concept with the soft piezoceramic material PIC151 successfully sustained all vibration requirements (17.8 gRMS random and 20 g sine) and shock testing (300 g SRS). We cover the mirror design development which reduces the stress in the brittle piezo-ceramic by 90 \% compared to the design from a former GSTP activity. We briefly address the optical characterization of the deformable mirror, namely the achieved Zernike amplitudes as well as the unpowered surface deformation (1.7 µm) and active flattening (12.3 nmRMS). The mirror produces low-order Zernike modes with a stroke of several tens of micrometer over a correction aperture of 50 mm, which makes the mirror a versatile tool for space telescopes.},
  language  = {en}
}
@inproceedings{RauschVerpoortWittrock2016,
  author    = {Rausch, Peter and Verpoort, Sven and Wittrock, Ulrich},
  title     = {Unimorph piezoelectric deformable mirrors for space telescopes},
  series = {Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, Proc. SPIE},
  volume    = {9904},
  booktitle = {Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, Proc. SPIE},
  doi       = {10.25974/fhms-923},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-9230},
  pages     = {990468},
  year      = {2016},
  abstract  = {We have developed, manufactured and tested a unimorph deformable mirror for space applications based on piezoelectric actuation. The mirror was designed for the correction of low-order Zernike modes with a stroke of several tens of micrometers over a clear aperture of 50 mm. It was successfully tested in thermal vacuum, underwent lifetime tests, and was exposed to random vibrations, sinusoidal vibrations, and to ionizing radiation. We report on design considerations, manufacturing of the mirror, and present the test results. Furthermore, we discuss critical design parameters, and how our mirror could be adapted to serve recently proposed space telescopes such as HDST and TALC.},
  language  = {de}
}
@inproceedings{VerpoortWittrock2010,
  author    = {Verpoort, Sven and Wittrock, Ulrich},
  title     = {Unimorph deformable mirror for telescopes and laser applications in space},
  series = {International Conference on Space Optics (ICSO), Rhodes Island, Greece},
  booktitle = {International Conference on Space Optics (ICSO), Rhodes Island, Greece},
  publisher = {SPIE},
  doi       = {10.25974/fhms-648},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-6484},
  year      = {2010},
  abstract  = {Over the past 5 years we have developed a new type of unimorph deformable mirror. The main advantages of this mirror technology are · very low surface scattering due to the use of superpolished glass · excellent coatings, even suitable for high power lasers, can be applied · active diameter of the mirrors can be between 10 mm and 100 mm · large strokes can be achieved even for small mirror diameters · integrated monolithic tip/tilt functionality based on a spiral arm design We have modeled these mirrors by analytical models as well as by the finite element method. This allows us to quickly design new mirrors tailored to specific applications. One example is a mirror for laser applications that has a diameter of 10 mm and can achieve a stroke in defocus mode of 5 μm. The stroke for these mirrors scales as the square of the mirror diameter, meaning that we can achieve, for example, a stroke of 125 μm for a mirror of 50 mm diameter. We will present design criteria and tradeoffs for these mirrors. We characterize our mirrors by the maximum stroke they can deliver for various Zernike modes, under the boundary condition that the Zernike mode has to be created with a certain fidelity, usually defined by the Mar{\´e}chal criterion.},
  language  = {en}
}
@article{RauschVerpoortWittrock2016,
  author    = {Rausch, Peter and Verpoort, Sven and Wittrock, Ulrich},
  title     = {Unimorph deformable mirror for space telescopes: environmental testing},
  series = {Opt. Expr.},
  volume    = {24},
  journal   = {Opt. Expr.},
  doi       = {10.25974/fhms-853},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-8530},
  pages     = {1528 -- 1542},
  year      = {2016},
  abstract  = {We have developed and manufactured a unimorph deformable mirror for space telescopes based on piezoelectric actuation. The mirror features 44 actuators, has an aperture of 50 mm, and is designed to reproduce low-order Zernike modes with a stroke of several tens of µm. We assessed the space compliance by operating the mirror in thermal vacuum, and exposing it to random and sinusoidal vibrations, as well as to ionizing irradiation. Additionally, the operational life time and the laser power handling capability were tested. The mirror was successfully operated in thermal vacuum at 100 K. We report on the conducted tests and the methods used to evaluate the mirror\&\#180;s performance, and discuss the compliance with the demanded requirements},
  language  = {de}
}
@article{RauschVerpoortWittrock2015,
  author    = {Rausch, Peter and Verpoort, Sven and Wittrock, Ulrich},
  title     = {Unimorph deformable mirror for space telescopes: design and manufacturing},
  series = {Opt. Expr.},
  volume    = {23},
  journal   = {Opt. Expr.},
  doi       = {10.25974/fhms-822},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-8227},
  pages     = {19469 -- 19477},
  year      = {2015},
  abstract  = {Large space telescopes made of deployable and lightweight structures suffer from aberrations caused by thermal deformations, gravitational release, and alignment errors which occur during the deployment procedure. An active optics system would allow on-site correction of wave-front errors, and ease the requirements on thermal and mechanical stability of the optical train. In the course of a project funded by the European Space Agency we have developed and manufactured a unimorph deformable mirror based on piezoelectric actuation. The mirror is able to work in space environment and is designed to correct for large aberrations of low order with high surface fidelity. This paper discusses design, manufacturing and performance results of the deformable mirror.},
  language  = {en}
}
@inproceedings{FreudlingGrzesikErhardetal.2021,
  author    = {Freudling, Maximilian and Grzesik, Andreas and Erhard, Markus and Gerhards, Maximilian and Leitz, Sinje and Verpoort, Sven and Wittrock, Ulrich and Hallibert, Pascal},
  title     = {Space-qualified piezo based deformable mirror for future instruments with active optics},
  series = {Proceedings of the International Conference on Space Optics (ICSO)},
  volume    = {11852},
  booktitle = {Proceedings of the International Conference on Space Optics (ICSO)},
  organization    = {ESA/ESTEC, Noordwijk},
  doi       = {10.25974/fhms-13741},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-137410},
  pages     = {1185231-11},
  year      = {2021},
  abstract  = {This paper presents the results of the technology development project "Enabling Technologies for Piezo-Based Deformable Mirrors in Active Optics Correction Chains" conducted by OHB System AG together with its partner M{\"u}nster University of Applied Sciences (MUAS). The project was funded by ESA within their General Support Technology Programme (GSTP). We address in this paper mainly the definition, flow-down and verification of the requirements for the Deformable Mirror (DM). The requirements were derived from a set of real space mission applications. The deformation of the mirror is performed by piezo-ceramic actuators in an unimorph configuration. The finally developed DM is able produce Zernike modes with a stroke of several tens of µm over a clear optical aperture of 50 mm in diameter. It underwent successfully a full environmental qualification campaign including thermal cycling, shock- and vibration testing, as well as exposure to proton and γ-ray radiation. Thermal and performance tests were performed in the temperature range from 100 K to 300 K. Furthermore, the DM sustained all vibration (random 17.8 g RMS and sinus) and shock (300 g) testing. Thereby all criticalities which were identified a previous study have been overcome successfully. A Technology Readiness Level (TRL) of 5 is reached, as the component has been validated in relevant environment. Based on the high level of maturity, this deformable mirror is now ready for the incorporation in future flight instruments. The achieved TRL of 5 is sufficient for the status of a PDR at payload level and gives thus a very good basis for all kinds of potential B2, C/D payload developments.},
  language  = {en}
}
@article{KazasidisVerpoortWittrock2020,
  author    = {Kazasidis, Orestis and Verpoort, Sven and Wittrock, Ulrich},
  title     = {Sensor for dynamic focus control of a deformable mirror},
  series = {Appl. Opt.},
  journal   = {Appl. Opt.},
  number    = {59},
  doi       = {10.1364/AO.392970},
  pages     = {5625 -- 5630},
  year      = {2020},
  abstract  = {We recently presented a novel unimorph deformable mirror which allows for dynamic focus shift with an actuation rate of 2 kHz. Such mirrors suffer from hysteresis and creep. Therefore, they have to be operated in closed-loop. For this purpose, we developed a defocus sensor based on an astigmatic detection system. In this paper, we present the sensor design and discuss its performance.},
  language  = {en}
}
@inproceedings{RauschVerpoortWittrock2014,
  author    = {Rausch, Peter and Verpoort, Sven and Wittrock, Ulrich},
  title     = {Performance verification and environmental testing of a unimorph deformable mirror for space applications.},
  series = {Proceedings of the 10th International Conference on Space Optics - ICSO, Tenerife, Spain},
  booktitle = {Proceedings of the 10th International Conference on Space Optics - ICSO, Tenerife, Spain},
  publisher = {FH M{\"u}nster},
  doi       = {10.25974/fhms-771},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-7716},
  year      = {2014},
  abstract  = {Concepts for future large space telescopes require an active optics system to mitigate aberrations caused by thermal deformation and gravitational release. Such a system would allow on-site correction of wave-front errors and ease the requirements for thermal and gravitational stability of the optical train. In the course of the ESA project "Development of Adaptive Deformable Mirrors for Space Instruments" we have developed a unimorph deformable mirror designed to correct for low-order aberrations and dedicated to be used in space environment. We briefly report on design and manufacturing of the deformable mirror and present results from performance verifications and environmental testing.},
  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}
}
@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}
}