SHEARING INTERFEROMETRY FOR LASER-GUIDE-STAR ATMOSPHERIC CORRECTION AT LARGE D/R(0)

Shearing interferometry offers a possible method to scale wave-front sensors to the large number of subapertures that will be required for correction of the new generation of large 6-10-m-class telescopes at visible wavelengths. We discuss static shearing interferometers, which are prototype wave-front sensors for use with laser guide stars at large values of D/r(0). The dc interferometers utilize low-noise detector array technology and can be implemented with a variety of shear lengths to accommodate different atmospheric conditions. We discuss the optical design and the noise sensitivity of two versions of de interferometer. Atmospheric tests of the interferometers for correcting a 500-subaperture adaptive system are presented, including fringe data obtained with ultraviolet and visible laser stars and compensated ultraviolet images of Vega obtained at our test facility in San Diego.