MCAO numerical simulations for EST: analysis and parameter optimization

The European Solar Telescope (EST) will be a new generation Solar telescope with the challenge of achieving a corrected field of view (FOV) of 1 arcminute with a minimum Strehl of 40% in the whole range of elevation angles of observation. For this purpose the EST will be equipped with a MCAO (Multi- conjugate Adaptive Optics) system. The proposed MCAO system for Solar telescopes combines a narrow and a wide extended Shack Hartman (SH) wavefront sensors (WFS) taking as references the spot or granulation of the sun. The number and position of deformable mirrors (DMs), the wavefront field of view (FOV), and asterism geometry have to be correctly settled as a function of the site turbulence conditions. We have performed numerical simulations using real turbulence profiles obtained at Observatorio del Teide in order to optimize the MCAO parameters for EST

MCAO numerical simulations for EST: analysis and parameter optimization

The European Solar Telescope (EST) will be a new generation Solar telescope with the challenge of achieving a corrected field of view (FOV) of 1 arcminute with a minimum Strehl of 40% in the whole range of elevation angles of observation. For this purpose the EST will be equipped with a MCAO (Multi- conjugate Adaptive Optics) system. The proposed MCAO system for Solar telescopes combines a narrow and a wide extended Shack Hartman (SH) wavefront sensors (WFS) taking as references the spot or granulation of the sun. The number and position of deformable mirrors (DMs), the wavefront field of view (FOV), and asterism geometry have to be correctly settled as a function of the site turbulence conditions. We have performed numerical simulations using real turbulence profiles obtained at Observatorio del Teide in order to optimize the MCAO parameters for EST

Analytical study of high altitude turbulence wide-field wavefront sensing: impact on the design and reconstruction quality of future solar AO systems

The European Solar Telescope is a 4-m planned facility designed to have high spatial resolution capabilities tounderstand the mechanisms of magnetic coupling in the chromosphere and the photosphere. It will feature both aconventional and a multi-conjugate adaptive optics (AO) of similar complexity than the systems for night-timeExtremely Large Telescopes. A particularity of solar AO is that it uses the solar granulation as a reference; therefore thewavefront sensing is performed using correlations on images with a field of view of ~10”. A sensor collecting such awide field of view averages wavefront information from different sky directions, affecting the sensing of high altitudeturbulence, the sampling of which does not depend anymore on the size of the subapertures only, but rather on the size ofthe projection of the extended field of view. Understanding this effect is crucial for the design of future solar facilities,i.e. to choose the adequate height of the DMs on MCAO systems, and also to predict the quality of the reconstructionthat such system would be able to achieve. For that reason, we have studied wide field sensing and found the analyticalequations that describe the process, in order to use this information as an input to improved designs of solar AO systems

Analytical study of high altitude turbulence wide-field wavefront sensing: impact on the design and reconstruction quality of future solar AO systems

The European Solar Telescope is a 4-m planned facility designed to have high spatial resolution capabilities tounderstand the mechanisms of magnetic coupling in the chromosphere and the photosphere. It will feature both aconventional and a multi-conjugate adaptive optics (AO) of similar complexity than the systems for night-timeExtremely Large Telescopes. A particularity of solar AO is that it uses the solar granulation as a reference; therefore thewavefront sensing is performed using correlations on images with a field of view of ~10”. A sensor collecting such awide field of view averages wavefront information from different sky directions, affecting the sensing of high altitudeturbulence, the sampling of which does not depend anymore on the size of the subapertures only, but rather on the size ofthe projection of the extended field of view. Understanding this effect is crucial for the design of future solar facilities,i.e. to choose the adequate height of the DMs on MCAO systems, and also to predict the quality of the reconstructionthat such system would be able to achieve. For that reason, we have studied wide field sensing and found the analyticalequations that describe the process, in order to use this information as an input to improved designs of solar AO systems

Preliminary performance analysis of a LGS system for GTC

The Gran Telescopio Canarias (GTC) Adaptive Optics (AO) system, designed to work with Natural Guide Stars (NGS), is in its laboratory integration phase. The upgrade for the operation with a Laser Guide Star (LGS) has been approved, and the design of the LGS Facility is going to start. Hereafter we analyse the performance of a LGS AO system taking into account the GTC characteristics and error budget. Two scenarios are studied: launching the laser from the centre of the telescope aperture behind the secondary (on axis) and launching from the side of the primary mirror (off axis). The simulations have been performed using the Fractal Iterative Method (FrIM), a fast-reconstruction algorithm, with the parameters of the GTC for the telescope, the atmospheric profiles of the Observatorio del Roque de Los Muchachos (ORM), and data from the laser star unit developed by ESO

Comparison of Reconstruction and Control algorithms on the ESO end-to-end simulator OCTOPUS

International audienceExtremely Large Telescopes are very challenging concerning their Adaptive Optics requirements. Their diameters, the specifications demanded by the science for which they are being designed for, and the planned use of Extreme Adaptive Optics systems, imply a huge increment in the number of degrees of freedom in the deformable mirrors. It is necessary to study new reconstruction algorithms to implement the real time control in Adaptive Optics at the required speed. We have studied the performance, applied to the case of the European ELT, of three different algorithms: the matrix-vector multiplication (MVM) algorithm, considered as a reference; the Fractal Iterative Method (FrIM); and the Fourier Transform Reconstructor (FTR). The algorithms have been tested on ESO's OCTOPUS software, which simulates the atmosphere, the deformable mirror, the sensor and the closed-loop control. The MVM is the default reconstruction and control method implemented in OCTOPUS, but it scales in O(N2) operations per loop so it is not considered as a fast algorithm for wave-front reconstruction and control on an Extremely Large Telescope. The two other methods are the fast algorithms studied in the E-ELT Design Study. The performance, as well as their response in the presence of noise and with various atmospheric conditions, has been compared using a Single Conjugate Adaptive Optics configuration for a 42 m diameter ELT, with a total amount of 5402 actuators. Those comparisons made on a common simulator allow to enhance the pros and cons of the various methods, and give us a better understanding of the type of reconstruction algorithm that an ELT demands

Results from a Lunar Laser Communication Experiment between NASA's LADEE Satellite and ESA's Optical Ground Station

ESA’s optical ground station (OGS) participated in the Lunar Laser Communication Demonstration (LLCD) with the Laser Communication Space Terminal (LLST) onboard NASA’s Lunar Atmosphere and Dust Environmental Explorer (LADEE) satellite. The experiment demonstrated the capabilities of optical communication and of inter-agency cross-support for optical communication links. The OGS experimental campaign, which started on October 26 and lasted until November 20, consisted of four days of bidirectional link sessions followed by three days of no operation. Each individual link session lasted approximately 20 minutes and was repeated after two hours. Despite non optimal weather conditions multiple link sessions were performed. The paper describes the design of the transmit laser and data generation system as well as the receiver system. A special chapter is dedicated to lessons learned from transmitter/receiver alignment problems, which prevented the demonstration of data uplink and ranging from the OGS. Several possibilities to solve the alignment problem are discussed and the finally implemented solution is described

The ORP on-sky community access program for adaptive optics instrumentation development

International audienc

ELT instrument concepts: impact on telescope and adaptive optics design

We report on the development of instrument concepts for a European ELT, expanding on studies carried out as part of the ESO OWL concept. A range of instruments were chosen to demonstrate how an ELT could meet or approach the goals generated by the OPTICON science team, and used to push the specifications and requirements of telescope and adaptive optics systems. Preliminary conclusions are presented, along with a plan for further more detailed instrument design and technology developments. This activity is supported by the European Community (Framework Programme 6, ELT Design Study, contract number 011863)