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Proceedings Paper

Hysteresis compensation in PZT bimorph mirrors: Preisach's classical and non-linear models
Author(s): Alfredo Dubra; John S. Massa; Carl Paterson
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Paper Abstract

A number of reflective wavefront correctors used in adaptive optics are based on the use of piezoelectric effect, either in piston, tip/tilt or curvature devices. The relation between the voltage applied to drive these devices and the mechanical response always presents hysteresis to some extent. In this work we study the performance of Preisach's classical and non-linear models of hysteresis on a bimorph mirror, which is a curvature device, but both models can also be applied to piston and tip/tilt devices. Bimorph mirrors with PZT actuators and a passive glass substrate were tested in an adaptive optics test-bed (AOTB) using a Shack-Hartmann wavefront sensor. First- and second-order reversal curves were sampled uniformly in Preisach space, and interpolation algorithms were implemented to test Preisach's classical and non-linear forward models respectively. Then, arbitrary voltage configuration sequences were applied to the mirror and the responses were recorded. Finally, the inversion of the models was implemented and included in the AOTB linear control algorithm to test the closed-loop performance. We found that both hysteresis models provide a similar improvement in the open-loop error. The improvement estimation depends on the particular sequence applied, the number of samples of the Preisach function and noise among other factors. Finally, we present data showing that the hysteretic behavior in a multi-electrode mirror is, within experimental error, independent of the electrode geometry, area and location.

Paper Details

Date Published: 8 June 2006
PDF: 8 pages
Proc. SPIE 6018, 5th International Workshop on Adaptive Optics for Industry and Medicine, 60181E (8 June 2006); doi: 10.1117/12.669384
Show Author Affiliations
Alfredo Dubra, Imperial College London (United Kingdom)
John S. Massa, Imperial College London (United Kingdom)
Carl Paterson, Imperial College London (United Kingdom)

Published in SPIE Proceedings Vol. 6018:
5th International Workshop on Adaptive Optics for Industry and Medicine
Wenhan Jiang, Editor(s)

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