Related papers: Metasurface-based Toroidal Lenslet Array Design fo…

Over the last few years increasing consideration has been given to the study of Laser Guide Stars (LGS) for the measurement of the disturbance introduced by the atmosphere in optical and near-infrared astronomical observations from the…

The new class of large telescopes, as the future ELT, are designed to work with Laser Guide Star (LGS) tuned to a resonance of atmosphere sodium atoms. This wavefront sensing technique presents complex issues for an application to big…

Sodium Laser Guide Stars (LGSs) are elongated sources due to the thickness and the finite distance of the sodium layer. The fluctuations of the sodium layer altitude and atom density profile induce errors on centroid measurements of…

Laser guide stars with adaptive optics allow astronomical image correction in the absence of a natural guide star. Single guide star systems with a star created in the earth's sodium layer can be used to correct the wavefront in the near…

The performance of adaptive optics systems is partially dependant on the algorithms used within the real-time control system to compute wavefront slope measurements. We demonstrate use of a matched filter algorithm for the processing of…

A method for producing a laser guide star wavefront sensor for adaptive optics with reduced focal anisoplanatism is presented. A theoretical analysis and numerical simulations have been carried out and the results are presented. The…

Precision wavefront control on future segmented-aperture space telescopes presents significant challenges, particularly in the context of high-contrast exoplanet direct imaging. We present a new wavefront control architecture that…

Adaptive optics to correct current telescopes over wide fields, or future very large telescopes over even narrow fields, will require real-time wavefront measurements made with a constellation of laser beacons. Here we report the first such…

Laser guide star (LGS) wave-front sensing (LGSWFS) is a key element of tomographic adaptive optics system. However, when considering Extremely Large Telescope (ELT) scales, the LGS spot elongation becomes so large that it challenges the…

We present an analytical derivation of the on-axis performance of Adaptive Optics systems using a given number of guide stars of arbitrary altitude, distributed at arbitrary angular positions in the sky. The expressions of the residual…

The performance of an adaptive optics (AO) system on a 100m diameter ground based telescope working in the visible range of the spectrum is computed using an analytical approach. The target Strehl ratio of 60% is achieved at 0.5um with a…

Shack-Hartmann wavefront sensors for both solar and laser guide star adaptive optics (with elongated spots) need to observe extended objects. Correlation techniques have been successfully employed to measure the wavefront gradient in solar…

Full sky coverage Adaptive Optics on Extremely Large Telescopes requires the adoption of several Laser Guide Stars as references.With such large apertures, the apparent elongation of the beacons is absolutely significant.With few…

Optical interferometry has been successful at achieving milliarcsecond resolution on bright stars. Imaging performance can improve greatly by increasing the number of baselines, which has motivated proposals to build large (~ 100 m) optical…

We have developed and tested a novel method, based on LIDAR, of measuring the height and profile of the mesospheric sodium layer using a continuous wave laser. It is more efficient than classical LIDAR as the laser is on for 50% of the…

The Max-Planck institutes for astronomy (MPIA) and for extraterrestrial physics (MPE) run an adaptive optics (AO) system with a laser guide star at the 3.5 m telescope on Calar Alto, Spain. This system, called ALFA, produces now scientific…

The performance of adaptive optics systems employing sodium laser guide stars can be improved by continuously monitoring the vertical density structure of mesospheric sodium along the line of sight. We demonstrate that sodium density…

Multi-Conjugate Adaptive Optics systems based on sodium Laser Guide Stars may exploit Natural Guide Stars to solve intrinsic limitations of artificial beacons (tip-tilt indetermination and anisoplanatism) and to mitigate the impact of the…

The use of Adaptive Optics in Extremely Large Telescopes brings new challenges, one of which is the treatment of Shack-Hartmann Wavefront sensors images. When using this type of sensors in conjunction with laser guide stars for sampling the…

Sub-wavelength resolution imaging requires high numerical aperture (NA) lenses, which are bulky and expensive. Metasurfaces allow the miniaturization of conventional refractive optics into planar structures. We show that high-aspect-ratio…