Abstract

Abstract
A novel technique to measure C2n and L0 in the atmosphere from anisokinetism in tip/tilt corrected images of star fields by fitting parameter-based PSF models, enabling a low-complexity 24×7 capability.

Abstract
The discrete sampling of a wave-front using a Shack-Hartmann sensor limits the maximum spatial frequency we can measure and impacts sensitivity to frequencies at the high end of the correction band due to aliasing. Here we present Wiener filters for wave-front reconstruction in the spatial-frequency domain, ideally suited for systems with a high number of degrees of freedom. We develop a theoretical anti-aliasing (AA) Wiener filter that optimally takes into account high-order wave-front terms folded in-band during the sensing (i.e., discrete sampling) process. We present Monte-Carlo simulation results for residual wave-fronts and propagated noise and compare to standard reconstruction techniques (in the spatial domain). To cope with finite telescope aperture we've developed and optimised a Gerchberg-Saxton like iterative-algorithm that provides superior performance.

Abstract
Investigations into the Pyramid wavefront sensor (P-WFS) have experimentally demonstrated the ability to achieve a better performance than with a standard Shack-Hartmann sensor (SH-WFS). Implementation on the Large Binocular Telescope (LBT) provided the first operational demonstration on a facility-class instrument of a P-WFS on sky. The desire to implement a Pyramid on an Extremely Large Telescope (ELT) requires further characterisation in order to optimise the performance and match our knowledge and understanding of other wave-front sensors (WFSs). Within the framework of the European Extremely Large Telescope (E-ELT), the Laboratoire d'Astrophysique de Marseille (LAM) is involved in the preparation of the Single Conjugate Adaptive Optics (SCAO) system of HARMONI, E-ELT's 1st light integral field spectrograph (IFU). The current baseline WFS for this adaptive optics system is a Pyramid WFS using a high speed and sensitive OCAM2 camera. At LAM we are currently carrying out laboratory demonstrations of a Pyramid-WFS, with the aim to fully characterise the behaviour of the Pyramid in terms of sensitivity and linear range. This will lead to a full operational procedure for the use of the Pyramid on-sky, assisting with current designs and future implementations. The final goal is to provide an on sky comparison between the Pyramid and Shack-Hartmann at Observatoire de la Côte d'Azur (OCA). Here we present our experimental setup and preliminary results.

Abstract
We analyze the altitude distribution of the turbulence outer scale - L0(h) - at Cerro Pachón from Gemini South MCAO (GeMS) loop data. GeMS turbulence profiler is fed with telemetry from their 5 WFSs and from the voltages applied to the deformable mirrors, providing estimations of r0, Cn2(h), wind profile (speed and direction for every layer), isoplanatic angle and the outer scale distribution L0(h). It is shown that this last parameter ranges from less than 1 meter at the ground to more than 50m (the telescope is insensitive to larger cannot detect differences above this value). The technique is based on cross correlations of the pseudo-open-loop slopes that allow to disentangle the multiple constituents of L0.

Abstract
MOSAIC is the proposed multiple object spectrograph for the E-ELT that will eventually combine two AO observing modes within a single instrument. MOSAIC will contain up to 20 open-loop multiple object AO channels feeding NIR IFUs in addition to up to 200 seeing-limited (or GLAO corrected) VIS - NIR fibre pickoffs. Wavefront tomography will be implemented using a combination of LGS and a few high-order NGS distributed across the field with the wavefront correction applied in a split open/closed loop configuration. MOSAIC will be the only E-ELT instrument planned that can utilize the full 10 arcminute diameter field of view, enabling highly efficient observing modes for this workhorse instrument. Use of the full E-ELT field inevitably requires a closer integration between the telescope control system and the instrument AO systems, however this can bring several potential benefits to overall system performance. Here we present the initial design concept and baseline performance of the MOSAIC instrument and AO system(s) taking advantage of the CANARY on-sky results and inheriting from the previous Phase A study of EAGLE. Finally, we will highlight areas of system performance and calibration that will require further analysis and trade-off during the course of the upcoming Phase A study.