HARMONI - first light spectroscopy for the ELT: novel techniques for the calibration of non-common path aberrations

Abstract

HARMONI is the first-light visible and near-IR integral field spectrograph for the E-ELT. Non-Common Path Aberrations between the Adaptive Optics channel and the science path are the main limitation for direct imaging of exoplanets. The next generation of Extremely Large Telescopes will require advanced techniques for NCPA calibration to exploit their full capabilities and open up a new era of exoplanet discoveries. Calibrating these aberrations with conventional techniques like Phase Diversity can become problematic when the instrument contains an image slicer (such as HARMONI and PCS for the E-ELT). In this context, we have characterised the impact of image slicers on the PSF, and developed an alternative approach to NCPA calibration based on Machine Learning, which can discriminate between intrinsic slicer effects and aberrations features in the PSF.