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Torben Anderssen. Profile picture.

Torben Andersen

Professor emeritus (Leave of Absence)

Torben Anderssen. Profile picture.

Progress in Developing a Low-Cost Large Deformable Mirror


  • Rikard Heimsten
  • Douglas G. MacMynowski
  • Torben Andersen

Summary, in English

Large (> 1m) deformable mirrors with hundreds or thousands of actuators are attractive for extremely large telescopes. Use of force actuators coupled to the mirror via suction cups, and electret microphones for position sensing, has the potential of substantially reducing costs. However, a mirror controlled with force actuators will have many structural resonances within the desired system bandwidth, shifting the emphasis somewhat of the control aspects. Local velocity and position loop for each actuator can add significant damping, but gives poor performance at high spatial frequencies. We therefore introduce a novel control strategy with many parallel "actuator families", each controlled by single-input-single-output controllers. This family approach provides performance close to that of global control, but without the accompanying robustness challenges. Using a complete simulation model of a representative large deformable mirror, we demonstrate feasibility of the approach. This paper describes the challenges of non-ideal actuators and sensors. The results presented give an understanding of the required actuator bandwidth and the effects of the sensors dynamics. The conclusion is that the introduction of actuator and sensor dynamics does not limit the control system of the deformable mirror.


  • Lund Observatory - Has been reorganised

Publishing year





Adaptive Optics Systems II



Document type

Conference paper




  • Astronomy, Astrophysics and Cosmology

Conference name

Conference on Adaptive Optics Systems II

Conference date

2010-06-27 - 2010-07-02




  • ISSN: 0277-786X
  • ISSN: 1996-756X