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Fourier transform wavefront reconstruction for the pyramid wavefront sensor

Abstract 164

Submitted by Fernando QUIROS-PACHECO


F. Quiros-Pacheco(1), C. Correia(2), S. Esposito(1)


(1) INAF-Arcetri; (2) ONERA.


We have studied the application of the Fourier Transform Reconstructor (FTR) to the pyramid wavefront sensor. This work is relevant, for instance, for the extreme AO system of EPICS (the planet finder for the E-ELT), in which the pyramid has been indentified as an optimal wavefront sensor for its halo rejection capabilities at small angular separations. It is envisaged that this XAO system will comprise 30000 actuators and subapertures. Clearly, the FTR would be advantageous to cope with such system dimensions.

We have investigated an optimized pyramid’s signal model for the FTR’s inverse filter. End-to-end simulations were performed both in open and closed loop to evaluate the performance of the FTR under different conditions (flux level, seeing) for an 8-m (40x40 subapertures) and a 42-m telescope (84x84 subapertures). Simulation results show that the performance of the FTR is of the same order of magnitude as the one obtained with the conventional vector-matrix multiply (VMM) method.

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