AO4ELT5 Proceedings

Numerical Evaluation of Pyramid Type Sensors for Extreme Adaptive Optics for the European Extremely Large Telescope

Clare, Richard (University of Canterbury), Engler, Byron (University of Canterbury), Weddell, Steve (University of Canterbury), Shatokhina, Iuliia (Industrial Mathematics Institute), Obereder, Andreas (MathConsult), Le Louarn, Miska (European Southern Observatory)

The pyramid wavefront sensor (WFS) is one of a class of WFSs that subdivide the spot at the focal plane into N sectors with an N-sided prism, creating N aperture images that can be used to estimate the wavefront aberration. In this paper, we show via end-to-end Monte Carlo simulations that for the European Extremely Largely Telescope (EELT), the pyramid (N=4) and roof WFSs (two orthogonal N=2-sided prisms) attain equivalent K band Strehl in the high flux and low read noise regime expected for an extreme adaptive optics (xAO) system. The N=3-sided prism is 3-6% worse in K band Strehl than the pyramid or roof WFSs for this 0 electron read noise case. However, for the low flux (5 photons/subaperture/frame) and with a read noise of 5 electrons/pixel/read, the 3-sided WFS yields a 12% higher Strehl than a conventional pyramid WFS. In addition, we show that the computationally efficient preprocessed cumulative reconstructor with domain decomposition (pCuReD) yields the same level of K band Strehl and an indistinguishable PSF profile as a conventional matrix-vector-multiply (MVM) reconstruction for both the pyramid and roof WFSs.

DOI: 10.26698/AO4ELT5.0011- Proceeding PDF

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