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MAORY stands for Multi-conjugate Adaptive Optics RelaY (the name has been recently changed to MORFEO, which stands for Multiconjugate adaptive Optics For ELT Observations, thus in this article we will use MORFEO), and it is one of the instruments of the European Extremely Large Telescope (ELT). The main function of MORFEO is to relay the light beam from the ELT focal plane to the client instrument (initially MICADO) while compensating, through a multiconjugate adaptive optics system, the effects of the atmospheric turbulence and other disturbances affecting the wavefronts coming from the scientific sources of interest.
The MORFEO instrument is designed and developed by a European consortium composed of INAF (Istituto Nazionale di AstroFisica, Italy), CNRS/INSU (Centre National de la Recherche Scientifique/ Institut National des Sciences de l’Univers, France), NUIG (National University of Ireland Galway, Ireland) and ESO (European Southern Observatory, Europe).
The opto-mechanical design of MORFEO has been developed in 3 dimensions, using the volume between the ELT output focal plane and the Nasmyth floor. The design uses the available volume in a very efficient way, but this poses constraints on the orientation of the optical elements and adds complexity to the AIT operations. In this paper we describe the strategy of the AIT process which will be performed at INAF-OAS Bologna (Italy), which is conceived to maximize knowledge of the instrument and thereby optimize (and, possibly, minimize) the time requested at Armazones for the AIV operations.
The infrared low order sensor (IRLOS) upgrade project was recently launched to increase the sky coverage of GALACSI narrow-field mode (NFM).1, 2 While the baseline is to perform low-order wavefront sensing with a 2x2 Shack-Hartmann wavefront sensor (SHWFS) operating in the J+H band, a full-pupil mode was proposed to address the faintest end of the magnitude range by concentrating the photons from the full aperture in a single point spread function (PSF). In this context, we have investigated the wavefront sensing approach called the linearized focal-plane technique (LIFT). It enables the retrieval of low-order modes such as tip/tilt, defocus, astigmatism (and possibly more) from a single focal-plane PSF of a very faint natural guide star (NGS) target. LIFT is a phase diversity technique based on introducing a known amount of astigmatism into the optical path. The morphological change induced by the astigmatic shift allows encoding information about the phase aberrations into the PSF morphology.
In this work, we discuss the linearity and flux sensitivity of the method and present experimental on-sky results obtained at the VLT. We discuss the applicability of this method in realistic conditions and the limitations that this method can face while operated on-sky.
In this paper we present some of the major results obtained and challenges encountered during the phase of System Tests, like the preparation of the Acquisition sequence, the testing of the Jitter loop, the performance optimization in GLAO and the offload of low-order modes from the DSM to the telescope (restricted to the M2 hexapod). The System Tests concluded with the successful acceptance, shipping, installation and first commissioning of GRAAL in 2015 as well as the acceptance and shipping of GALACSI, ready for installation and commissioning early 2017.
Besides the technological challenge itself, one critical area of AOF is the AO control strategy and its link with the telescope control, including Active Optics used to shape M1. Another challenge is the request to minimize the overhead due to AOF during the acquisition phase of the observation.
This paper presents the control strategy of the AOF. The current control of the telescope is first recalled, and then the way the AO control makes the link with the Active Optics is detailed. Lab results are used to illustrate the expected performance. Finally, the overall AOF acquisition sequence is presented as well as first results obtained on sky with GRAAL.
In this paper, the laser tomographic reconstruction process is described. Several methods (virtual DM, virtual layer projection) are studied, under the constraint of a single matrix vector multiplication. The pseudo-synthetic interaction matrix model and the LTAO reconstructor design are analysed. Moreover, the reconstruction parameter space is explored, in particular the regularization terms.
Furthermore, we present here the strategy to define the modal control basis and split the reconstruction between the Low Order (LO) loop and the High Order (HO) loop. Finally, closed loop performance obtained with a 3D turbulence generator will be analysed with respect to the most relevant system parameters to be tuned.
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