A Shack-Hartmann wavefront sensor projected onto the sky with reduced   focal anisoplanatism
  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 technique, named SPLASH (Sky-Projected Laser Array Shack-Hartmann), is shown to suffer considerably less from focal anisoplanatism than a conventional laser guide star system. The method is potentially suitable for large telescope apertures (~8m), and possibly for extremely large telescopes. 
T. Butterley, G. D. Love, R. W. Wilson, R. M. Myers, T. J. Morris