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The point spread function of a segmented aperture is seriously affected by the misalignment of the segments. Stringent requirements apply to position sensors and their calibration. The Active Phasing Experiment (APE) will be a technical instrument aimed at testing possible phasing techniques for a European Giant Optical Telescope (EGOT) in a representative(More)
This paper addresses the application of observer-based control techniques for the adaptive optics system of the LBT telescope. In such a context, attention is focused on the use of Kalman and H ∞ filters to estimate the temporal evolution of phase perturbations due to the atmospheric turbulence and the telescope vibrations acting on tip/tilt modes. We shall(More)
We analyze in details the standard Primordial Nucleosynthesis scenario. In particular we discuss the key theoretical issues which are involved in a detailed prediction of light nuclide abundances, as the weak reaction rates, neutrino decoupling and nuclear rate modelling. We also perform a new analysis of available data on the main nuclear processes(More)
A new adaptive optics system for the eye using a pyramid wavefront sensor interfaced in closed-loop with a piezoelectric deformable mirror is presented. Sensing parameters such as CCD integration time, pupil sampling and beam steering amplitude are tested on the bench and in vivo on several volunteers to optimize real-time optical correction. The system(More)
We review astronomical results in the visible (λ<1µm) with adaptive optics. Other than a brief period in the early 1990s, there has been little astronomical science done in the visible with AO until recently. The most productive visible AO system to date is our 6.5m Magellan telescope AO system (MagAO). MagAO is an advanced Adaptive Secondary system at the(More)
We describe some novel technical approaches to implement multi-pyramid wavefront sensing, partially extendable to single pyramid and to any MCAO system. First we introduce an achromatic version of the pyramid, which allows for a much better spatial resolution on the pupil and also relaxes the specifications in term of turned edges. Then we discuss the(More)
We present diffraction-limited Ks band and L adaptive optics images of the edge-on debris disk around the nearby F2 star HD 15115, obtained with a single 8.4 m primary mirror at the Large Binocular Telescope. At the Ks band, the disk is detected at signal-to-noise per resolution element (SNRE) ∼ 3–8 from ∼1 to 2. 5 (45–113 AU) on the western side and from(More)
We give a detailed account of the recent retrieval of a consistent amount (about 600 pages) of documents written by Enrico Fermi and/or his collaborators, coming from different sources previously unexplored. These documents include articles, patents, reports, notes on scientific and technical meetings and other papers, mainly testifying Fermi's activity in(More)
A Zernike decomposition of the pupil phase variance due to focus anisoplanatism for sodium laser guide star has been calculated, including the angular error variance associated with overall tilt. This last quantity, or tilt focus anisoplanatism 2 FA;tt , is necessary in evaluating the usefulness of new techniques developed to measure the wave-front tilt(More)