Abstract

When using a laser guide star (LGS) as the reference object in an adaptive optics system the accuracy of the correction is limited by the so-called 'cone-effect' or focal anisoplanatisism (FA). There are two effects

a) the footprint of the LGS wavefront at the turbulent layer is smaller than that for the wavefront from the science object and

b) the LGS wavefront expands by a factor of (1+h_turb/h_Na) when it reaches the telescope pupil. For example - with the height of turbulence h_turb =6.5 km and the height of laser guide star h_Na=90km at the edge of an 8m pupil there is a displacement of ≈30cm between the actual and measured wavefront from a science object

© 1996 Optical Society of America