<title>Multitiered wavefront sensor using binary optics</title>

Wavefront sensors have been used to make measurements in fluid-dynamics and for closed loop control of adaptive optics. In most common Shack-Hartmann wavefront sensors, the light is broken up into series of rectangular or hexagonal apertures that divide the light into a series of focal spots. The position of these focal spots is used to determine the wavefront slopes over each subaperture. Using binary optics technology, we have developed a hierarchical or fractal wavefront sensor that divides the subapertures up on a more optimal fashion. We have demonstrated this concept for up to four tiers and developed the wavefront reconstruction methods for both segmented adaptive optics and continuous wavefront measurement.