@article{KazasidisVerpoortSolovievetal.2018,
  author    = {Kazasidis, Orestis and Verpoort, Sven and Soloviev, Oleg and Vdovin, Gleb and Verhaegen, Michel and Wittrock, Ulrich},
  title     = {Extended-image-based correction of aberrations using a deformable mirror with hysteresis},
  series = {Opt. Expr.},
  volume    = {26},
  journal   = {Opt. Expr.},
  doi       = {10.1364/OE.26.027161},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-14759},
  pages     = {27161 -- 27178},
  year      = {2018},
  abstract  = {With a view to the next generation of large space telescopes, we investigate guide-star-free, image-based aberration correction using a unimorph deformable mirror in a plane conjugate to the primary mirror. We designed and built a high-resolution imaging testbed to evaluate control algorithms. In this paper we use an algorithm based on the heuristic hill climbing technique and compare the correction in three different domains, namely the voltage domain, the domain of the Zernike modes, and the domain of the singular modes of the deformable mirror. Through our systematic experimental study, we found that successive control in two domains effectively counteracts uncompensated hysteresis of the deformable mirror.},
  language  = {en}
}
@inproceedings{KazasidisVerpoortWittrock2018,
  author    = {Kazasidis, Orestis and Verpoort, Sven and Wittrock, Ulrich},
  title     = {Algorithm design for image-based wavefront control without wavefront sensing},
  series = {SPIE Optical Instrument Science, Technology, and Applications, Proc. SPIE},
  volume    = {10695},
  booktitle = {SPIE Optical Instrument Science, Technology, and Applications, Proc. SPIE},
  doi       = {10.1117/12.2312523},
  url       = {http://nbn-resolving.de/urn:nbn:de:hbz:836-opus-14760},
  pages     = {1069502},
  year      = {2018},
  abstract  = {Active optics is an enabling technology for future large space telescopes. Image-based wavefront control uses an image-sharpness metric to evaluate the optical performance. A control algorithm iteratively adapts a corrective element to maximize this metric, without reconstructing the wavefront. We numerically study a sharpness metric in the space of Zernike modes, and reveal that for large aberrations the Zernike modes are not orthogonal with respect to this metric. The findings are experimentally verified by using a unimorph deformable mirror as corrective element. We discuss the implications for the correction process and the design of control algorithms.},
  language  = {en}
}