Lessons learned from developing turbulence profilers for telescopes' instruments Lessons learned from developing turbulence profilers for telescopes' instruments

International audienceThis article presents the results obtained during three years of developing turbulence profilers for two different telescopes; namely Gemini South and the future Adaptive Optics Facility (AOF). The profilers are embedded in a facility instrument that provides the data from the Shack-Hartmann wavefront sensors which feed the SLODAR approach used to generate the profiles. The main results focused on two unsolved problems: dealing with the dome seeing and the effect of the atmosphere outer scale on the accuracy of the profilers

Fourier filter LGS wavefront sensing for ELT size telescopes

International audienc

Effect of the influence function of deformable mirrors on laser beam shaping

International audienc

Analysis of High-Efficiency Solar Cells in Mobile Robot Applications

This technical brief analyzes the performance of triple-junction solar cells on a mobile robot. Although originally designed for satellite use, it is demonstrated that triple-junction cells are effective in terrestrial applications. This makes them particularly suitable for systems with limited size and mass but high-power requirements such as a mobile robot. A testing station was specially constructed to characterize triple-junction and conventional silicon cell performance in different environments and to compare their effectiveness. Additional field tests were carried out with an autonomous robot in order to check the ability to deliver sufficient power to varying loads. Results show that they surpass conventional technologies with efficiencies higher than 22%, so they can be considered as an alternative technology for power sources onboard of terrestrial mobile robots. �DOI: 10.1115/1.2735361

Using artificial neural networks for open-loop tomography

Modern adaptive optics (AO) systems for large telescopes require tomographic techniques to reconstruct the phase aberrations induced by the turbulent atmosphere along a line of sight to a target which is angularly separated from the guide sources that are used to sample the atmosphere. Multi-object adaptive optics (MOAO) is one such technique. Here, we present a method which uses an artificial neural network (ANN) to reconstruct the target phase given off-axis references sources. We compare our ANN method with a standard least squares type matrix multiplication method and to the learn and apply method developed for the CANARY MOAO instrument. The ANN is trained with a large range of possible turbulent layer positions and therefore does not require any input of the optical turbulence profile. It is therefore less susceptible to changing conditions than some existing methods. We also exploit the non-linear response of the ANN to make it more robust to noisy centroid measurements than other linear techniques

An on-line turbulence profiler for the AOF: on-sky results

International audienc

Laboratory validation of a laser shaping system before guide star projection

editorial reviewedMultiple sodium laser beacons are a crucial development in multi-conjugate adaptive optics systems that offers wide-field diffraction limited adaptive optics correction to the astronomical community. This correction is strongly dependent on the laser beam power and quality, so a beam shaping concept is currently being developed to speed-up calibration and alignment of the laser before every run. A method previously reported, has now been implemented on a laboratory bench using MEMS deformable mirrors. Necessary calibration and characterization of the deformable mirrors are described and the results for experimental amplitude correction are presented