Eric Gendron

Performance and results of the COME-ON+ adaptive optics system at the ESO 3.6-m telescope

The COME-ON+ adaptive optics system was set up on the ESO 3.6-meter telescope for two technical runs (in December 1992 and April 1993) and is now routinely used for astronomical observations. This system is an upgrade of the COME-ON adaptive optics prototype system. During the technical runs, images were recorded in the V, I, J, K and L spectral bands. Currently, the best resolution obtained is 0.1 in H (1.65 micrometers ) under bad seeing conditions (seeing > 1 and averaged wind speed > 10 m/s) and reference star magnitudes of 6 to 8. The corresponding Strehl ratio is 35%. 70% Strehl ratio was obtained at 2.2 micrometers (K band). At 0.9 micrometers (I band), in the partial correction regime, the resolution is of the order of 0.2 for 0.8 seeing and 10 m/s averaged wind speed. The optimized modal control has been used on faint reference stars. The limiting magnitude (in V band) for wavefront sensing has been measured to 14 and 15 depending on the spectral type of the reference star and the seeing conditions for a low frequency tip-tilt correction.

ADONIS: a user-friendly adaptive optics system for the ESO 3.6-m telescope

ADONIS (ADaptive OPtics Near Infrared System) is an upgrade of the COME-ON+ adaptive optics prototype. It will allow the astronomical community to use adaptive optics as a common user instrument. This paper describes the main features of the new system, including a mechanical and optical interface for specific visitor equipment and imaging capabilities. We present here the 128 X 128 infrared imaging camera, covering the 1 - 5 micrometers spectral range.

Adaptive optics for high-resolution imagery: control algorithms for optimized modal corrections

Recent advances in adaptive optics control techniques have demonstrated the interest of modal control in astronomical applications in comparison with a nodal control. This paper describes the advantages to use such a control for the Come-On-Plus project. The different steps of nodal and modal control algorithms used for this experiment are given.

Real-time end-to-end AO simulations at ELT scale on multiple GPUs with the COMPASS platform

The COMPASS platform was designed to meet the need for high-performance for the simulation of AO systems. Taking advantage of the specific hardware architecture of the GPU, the COMPASS tool allows the AO scientist to obtain adequate execution speeds and to conduct large simulation campaigns scaled to the E-ELT dimensioning for a variety of AO flavors from SCAO to MOAO. On the latest GPU architecture (NVIDA Volta), execution speeds of several hundreds of short exposure PSF per second can be achieved for a SCAO system on the E-ELT, making the COMPASS platform a real-time end-to-end simulation tool. In this paper, we provide a full description of the critical physical models used in the simulation pipeline, review a range AO system configurations that can be addressed with COMPASS and report on the time to solution obtained for this systems. Scalability over multiple GPUs and multiple generations of GPUs is also discussed.

Scalable soft real-time supervisor for tomographic AO

Implementations of AO tomography for the next generation of Extremely Large Telescopes (ELTs) is challenging because of the extremely large number of degrees of freedom of such systems, in particular when it comes to the tomographic reconstructor computation, due to its size. The computation of this matrix, via the supervisor module, requires leveraging high performance computing techniques, on shared or distributed memory systems, to comply with the specifications of tomographic AO systems, which prescribe an update rate of the order of few minutes. In the scope of the Green-Flash project, we are exploring several approaches to optimize the execution of this soft real-time supervision pipeline. This includes low-rank techniques to reduce the computational load. We have tested several compression schemes to optimize the linear algebra involved in the tomographic reconstructor as well as the computation of the covariance matrices involved in this process. We present, in this paper, the scalable and portable pipeline we have developed to address these issues. Performance in terms of time to solution and scalability are reported. Additionally, the case of low-rank algorithms is stressed as both an attempt to address the computation challenge of the tomographic reconstructor for the supervisor module, and a way to reduce the computational load (hence the overall RTC system latency) at the level of the real-time data pipeline.

Deriving comprehensive error breakdown for wide field adaptive optics systems using end-to-end simulations

The future European Extremely Large Telescope (E-ELT) adaptive optics (AO) systems will aim at wide field correction and large sky coverage. Their performance will be improved by using post processing techniques, such as point spread function (PSF) deconvolution. The PSF estimation involves characterization of the different error sources in the AO system. Such error contributors are difficult to estimate: simulation tools are a good way to do that. We have developed in COMPASS (COMputing Platform for Adaptive opticS Systems), an end-to-end simulation tool using GPU (Graphics Processing Unit) acceleration, an estimation tool that provides a comprehensive error budget by the outputs of a single simulation run.

Phase A AO system design and performance for MOSAIC at the ELT

MOSAIC is a mixed-mode multiple object spectrograph planned for the ELT that uses a tiled focal plane to support a variety of observing modes. The MOSAIC AO system uses 4 LGS WFS and up to 4 NGS WFS positioned anywhere within the full 10 arcminute ELT field of view to control either the ELT M4/5 alone for GLAO operation feeding up to 200 targets in the focal plane, or M4/5 in conjunction with 10 open-loop DMs for MOAO correction. In this paper we present the overall design and performance of the MOSAIC GLAO and MOAO systems.

Maximum likelihood approach for the adaptive optics point spread function reconstruction

This paper is dedicated to a new PSF reconstruction method based on a maximum likelihood approach (ML) which uses as well the telemetry data of the AO system (see Exposito et al. (2013)1). This approach allows a joint-estimation of the covariance matrix of the mirror modes of the residual phase, the noise variance and the Fried parameter r0. In this method, an estimate of the covariance between the parallel residual phase and the orthogonal phase is required. We developed a recursive approach taking into account the temporal effect of the AO-loop, so that this covariance only depends on the r0, the wind speed and some of the parameters of the system (the gain of the loop, the interaction matrix and the command matrix). With this estimation, the high bandwidth hypothesis is no longer required to reconstruct the PSF with a good accuracy. We present the validation of the method and the results on numerical simulations (on a SCAO system) and show that our ML method allows an accurate estimation of the PSF in the case of a Shack-Hartmann (SH) wavefront sensor (WFS).

Artificial intelligence system and optimized modal control for the ADONIS adaptive optics instrument

ADONIS is an adaptive optics user friendly instrument for the ESO 3.6-m telescope. The modal control technique is presented as a tool for optimizing the control of ADONIS. The perturbed wavefront is spread over a base of modes treated by the system in terms of their behavior with respect to the observing conditions (turbulence characteristics, anisoplanatic angle and star magnitude). This optimization and the multiple parameters influencing the system performance are difficult to handle by the astronomer. Moreover, the wide range of situations the astronomical AO system has to deal with requires a flexible configuration which has to be optimized for each case. The ADONIS instrument also has to be easy to use by an astronomer without who doesnt have a deep knowledge of the AO techniques. Finally, it must make an efficient use of the telescope time. Hence, a new human interface and an intelligent control system are designed.

New adaptive optics prototype system for the ESO 3.6-m telescope: Come-on-Plus

Following the successful astronomical runs of the Come-On adaptive optics prototype on the ESO 3.6 m telescope in La Silla, Chile an upgraded version called Come-On-Plus is currently being constructed and was set up in December 1992. This paper describes the main improvements of this new system. In particular, the 52 actuator deformable mirror with 30 Hz closed loop bandwidth, the modal control, the high detectivity wavefront sensor channel, and the infrared imaging channel are presented. Finally, the laboratory tests of each subsystem are analyzed. This second prototype is dedicated to routine astronomical observing as well as providing design parameters for the adaptive optics for the ESO Very Large Telescope (VLT).