The Slope-Oriented Hadamard scheme for in-lab or on-sky interaction matrix calibration


Serge Meimon, Thierry Fusco, Cyril Petit




The correct calibration of the interaction matrix affects the performance of an adaptive optics system. In the case of high-order systems, when the number of mirror modes is worth a few thousands, the calibration strategy is critical to reach the maximum interaction matrix quality in the minimum time. This is all the more true for the E-ELT, for which on sky calibration procedures have to be considered. Here, we first build a tractable interaction matrix quality criterion. We then propose the Slope-Oriented Hadamard scheme which optimizes this quality criterion.

We demonstrate that for a given level of quality, the calibration time needed using the Slope-Oriented Hadamard method is ten times less than with a classical Hadamard scheme. These analytical and simulation results are confirmed experimentally both on the ONERA AO bench (BOA) and on the SPHERE XAO system (SAXO).

Last, we show how to use this method in an on-sky calibration scheme, and we quantify the gain in time compared to other calibration strategies.

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