TY  - JOUR
A1  - Kazasidis, Orestis
A1  - Verpoort, Sven
A1  - Soloviev, Oleg
A1  - Vdovin, Gleb
A1  - Verhaegen, Michel
A1  - Wittrock, Ulrich
T1  - Extended-image-based correction of aberrations using a deformable mirror with hysteresis
JF  - Opt. Expr.
N2  - 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.
KW  - active optics, metrics, aberration compensation
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-14759
UR  - https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-26-21-27161&id=398820
VL  - 26
SP  - 27161
EP  - 27178
ER  - 
TY  - JOUR
A1  - Kazasidis, Orestis
A1  - Verpoort, Sven
A1  - Wittrock, Ulrich
T1  - Aberration balancing using an image-sharpness metric
JF  - J. Opt. Soc. Am. A
N2  - Image-sharpness metrics can be used to optimize optical systems and to control wavefront sensorless adaptive optics systems. We show that for an aberrated system, the numerical value of an image-sharpness metric can be improved by adding specific aberrations. The optimum amplitudes of the additional aberrations depend on the power spectral density of the spatial frequencies of the object.
KW  - adaptive optics; image-sharpness
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-109198
UR  - https://www.osapublishing.org/josaa/abstract.cfm?uri=josaa-36-8-1418
VL  - 36
IS  - 8
SP  - 1418
EP  - 1422
ER  - 
TY  - JOUR
A1  - Rausch, Peter
A1  - Verpoort, Sven
A1  - Wittrock, Ulrich
T1  - Unimorph deformable mirror for space telescopes: design and manufacturing
JF  - Opt. Expr.
N2  - 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.
KW  - Active or adaptive optics
KW  - Telescopes
KW  - Space optics
KW  - Space instrumentation
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-8227
VL  - 23
SP  - 19469
EP  - 19477
ER  -