Laser guide artificial star for high resolution imaging

Abstract

A large telescope encodes the information about the source, but unable to get the di raction-limited informations. Due to the inhomogeneity of the propagating medium that carries the light to the Earth's surface, the image of a point source (unresolved stars) cannot be smaller than a limit at the focal plane of the telescope. In order to estimate the point spread function of both the atmosphere and the telescope, observation of a bright unresolved star is needed. Astronomers do face disculties in locating such an object within isoplanatic patch. Over the years, several observatories have developed the laser guide arti cial star in order to palliate the limitations of low sky coverage (the probability of nding a suitable reference star within isoplanatic patch). This article discusses the utility of such an instrument.