An adjustable, high sensitivity, wide dynamic range two channel wave-front sensor based on moiré deflectometry

An adjustable, high sensitivity, wide dynamic range two channel wave-front sensor based on moiré deflectometry has been constructed for measuring distortions of light wave-front transmitted through the atmosphere. In this approach, a slightly divergent laser beam is passed through the turbulent ground level atmosphere and then a beam-splitter divides it into two beams. The beams pass through a pair of moiré deflectometers which are installed parallel and close together. From deviations in the moiré fringes we calculate the two orthogonal components of angle of arrival at each location across the wave-front. The deviations have been deduced in successive frames which allows evolution of the wave-front shape to be determined. The dynamic range and sensitivity of detection are adjustable by merely changing the separation of the gratings and the angle between the rulings of the gratings in both of channels. The spatial resolution of the method is also adjustable by means of bright, dark, and virtual traces for given moiré fringes without paying a toll in the measurement precision.