VASAO two-color and seismometer experiments
K. Ho, D.Salmon, D.Sabin, C. Veillet

Abstract: Two experiments are currently being carried out at CFHT for the VASAO initiative. The first is to evaluate techniques for determining atmospheric tilt by measuring the separation between two colors from starlight, which then could be applied to the polychromatic laser guide star. The second is to measure telescope vibrations using a highly sensitive seismometer. Telescope vibrations cause achromatic tilt in the polychromatic laser guide star that cannot removed, unlike AO systems using natural guide stars, which inherently compensate for telescope vibrations. The signal derived from the vibration measurements could be used to drive a tip-tilt mirror in the optical path to remove the achromatic tilt.