Giovanni Bregoli

A preliminary overview of the multiconjugate adaptive optics module for the E-ELT

The multi-conjugate adaptive optics module for the European Extremely Large Telescope has to provide a corrected field of medium to large size (up to 2 arcmin), over the baseline wavelength range 0.8-2.4 μm. The current design is characterized by two post-focal deformable mirrors, that complement the correction provided by the adaptive telescope; the wavefront sensing is performed by means of a high-order multiple laser guide star wavefront sensor and by a loworder natural guide star wavefront sensor. The present status of a two years study for the advanced conceptual design of this module is reported.

Conceptual design and performance of the multiconjugate adaptive optics module for the European Extremely Large Telescope

The Multi-conjugate Adaptive Optics RelaY (MAORY) for the European Extremely Large Telescope (E-ELT) provides a corrected field of view of up to 2 arcmin diameter over the wavelength range 0.8-2.4 μm. It is expected to achieve a correction of high quality and uniformity with high sky coverage: with a seeing of 0.8 arcsec in the visible, the expected Strehl Ratio averaged over a 1 arcmin field is approximately 50% at 2.16 μm wavelength over 50% of the sky at the Galactic Pole. Wavefront correction is obtained by means of the E-ELT adaptive mirrors M4/M5 and of two post-focal deformable mirrors conjugated at 4km and 12.7km from the telescope pupil. Wavefront sensing is performed by 6 Sodium laser guide stars and by 3 natural guide stars, used to measure atmospheric and windshake tilt and to provide a reference for the focus and for the low-order aberrations induced by the Sodium layer. MAORY is located on the E-ELT Nasmyth platform and has a gravity invariant port, feeding the high angular resolution camera MICADO, and a lateral port for a detached instrument as the infrared spectrograph SIMPLE.

Preparing for the phase B of the E-ELT MCAO module project

The Multi-Conjugate Adaptive Optics module for the European Extremely Large Telescope has been designed to achieve uniform compensation of the atmospheric turbulence effects on a wide field of view in the near infrared. The design realized in the Phase A of the project is undergoing major revision in order to define a robust baseline in view of the next phases of the project. An overview of the on-going activities is presented.

End to end numerical simulations of the MAORY multiconjugate adaptive optics system

MAORY is the adaptive optics module of the E-ELT that will feed the MICADO imaging camera through a gravity invariant exit port. MAORY has been foreseen to implement MCAO correction through three high order deformable mirrors driven by the reference signals of six Laser Guide Stars (LGSs) feeding as many Shack- Hartmann Wavefront Sensors. A three Natural Guide Stars (NGSs) system will provide the low order correction. We develop a code for the end-to-end simulation of the MAORY adaptive optics (AO) system in order to obtain high-fidelity modeling of the system performance. It is based on the IDL language and makes extensively uses of the GPUs. Here we present the architecture of the simulation tool and its achieved and expected performance.

Photon counting CCDs as wavefront sensors for A.O.

Limiting magnitude of A.O. reference stars is set by wavefront sensor intrinsic noise. Recently available avalanche intensified CCD detectors allow single photon event detection (photon counting) virtually free from readout noise. The paper describes a program started in spring 2002, aiming to use a Marconi L3CCD as a wavefront sensor for A.O.

MAORY: adaptive optics module for the E-ELT

MAORY is one of the four instruments for the E-ELT approved for construction. It is an adaptive optics module offering two compensation modes: multi-conjugate and single-conjugate adaptive optics. The project has recently entered its phase B. A system-level overview of the current status of the project is given in this paper.

An Infrared Test Camera for LBT adaptive optics commissioning

A joint project among INAF--Osservatorio Astronomico di Bologna (Italy), Università di Bologna--Dipartimento di Astronomia (Italy) and Max-Planck-Institut für Astronomie (Heidelberg, Germany) led in about one year to the construction of two infrared test cameras for the LBT Observatory. Such cameras will be used to test the performance achieved by the telescope adaptive optics system as well as to prepare the telescope pointing model and to completely test all the focal stations at the Gregorian focus. In the present article the design and the integration of the two test cameras are described. The achieved performances are presented as well.

The numerical simulation tool for the MAORY multiconjugate adaptive optics system

The Multiconjugate Adaptive Optics RelaY (MAORY) is and Adaptive Optics module to be mounted on the ESO European-Extremely Large Telescope (E-ELT). It is an hybrid Natural and Laser Guide System that will perform the correction of the atmospheric turbulence volume above the telescope feeding the Multi-AO Imaging Camera for Deep Observations Near Infrared spectro-imager (MICADO). We developed an end-to-end Monte- Carlo adaptive optics simulation tool to investigate the performance of a the MAORY and the calibration, acquisition, operation strategies. MAORY will implement Multiconjugate Adaptive Optics combining Laser Guide Stars (LGS) and Natural Guide Stars (NGS) measurements. The simulation tool implement the various aspect of the MAORY in an end to end fashion. The code has been developed using IDL and use libraries in C++ and CUDA for efficiency improvements. Here we recall the code architecture, we describe the modeled instrument components and the control strategies implemented in the code.

Numerical simulations of MAORY MCAO module for the ELT

MAO (MAORY Adaptive Optics) is the a developed numerical simulation tool for adaptive optics. It was created especially to simulate the performance of the MAORY MCAO module of the Extremely Large Telescope. It is a full end-to-end Monte-Carlo code able to perform different flavors of adaptive optics simulation. We used it to investigate the performance of a the MAORY and some specific issue related to calibration, acquisition and operation strategies. As, MAORY, MAO will implement Multi-conjugate Adaptive Optics combining Laser Guide Stars (LGS) and Natural Guide Stars (NGS) measurements. The implementation of the reference truth WFS completes the scheme. The simulation tool implements the various aspect of the MAORY in an end to end fashion. The code has been developed using IDL and use libraries in C++ and CUDA for efficiency improvements. Here we recall the code architecture, we describe the modeled instrument components and the control strategies implemented in the code.

Accurate laser guide star wavefront sensor simulation for the E-ELT first light adaptive optics module

MAORY will be the multi-conjugate adaptive optics module for the E-ELT first light. The baseline is to operate wavefront sensing using 6 Sodium Laser Guide Stars and 3 Natural Guide Stars to solve intrinsic limitations of artificial beacons and to mitigate the impact of the sodium layer structure and variability. In particular, some critical components of MAORY require to be designed and dimensioned in order to reduce the spurious effects arising from the Sodium Layer density distribution and variation. The MAORY end-to-end simulation code has been designed to accurately model the Laser Guide Star image in the Shack-Hartmann wavefront sensor sub-apertures and to allow sodium profile temporal evolution. The fidelity with which the simulation code translates the sodium profiles in Laser Guide Star images at the wavefront sensor focal plane has been verified using a laboratory Prototype.