Ph.D. Defense: Tianquan Su

    Wednesday, November 12, 2014 - 2:00pm
    Meinel 554

    “Aspherical Surface Metrology with the Scanning Long-Wave Optical Test System”


    Aspherical optics are increasingly used these days. The application of aspherical surfaces on large, astronomical telescope mirrors brings challenges to fabrication. Since the surface radius of curvature varies across the surface, the grinding and polishing tool needs to change its shape when working on different parts of the surface, making surface error more easily embedded into the surface. Therefore, a tighter test-fab loop is needed to guide the fabrication process. To maximize the accuracy during the grinding of the surface and to minimize the working time in the polishing stage, a better metrology device that can measure rough surface is needed to guide the grinding process. Scanning long-wave optical test system is designed to meet this demand by providing accurate, fast, large-dynamic-range and high-spatial-resolution measurements on rough optical surfaces (surface root-mean-square roughness less than 1.7 micrometers).