Ph.D. Defense: Run Huang

    Monday, July 27, 2015 - 1:00pm
    Meinel 447

    "High-Precision Optical Surface Metrology Using Deflectometry"


    The Software Configurable Optical Test System developed at University of Arizona is a highly efficient optical metrology technique based on the principle of deflectometry, which can achieve comparable accuracy with interferometry but with low-cost hardware. In a SCOTS test, an LCD display is used to generate a structured light pattern to illuminate the test optics, and the reflected light is captured by a digital camera. The surface slope of the test optics is determined by triangulation of the display pixels, test optics and the camera. The surface shape is obtained by the integration of the slopes.

    Comparing to interferometry, which has long served as an accurate noncontact optical metrology technology, SCOTS overcomes the limitation of dynamic range and sensitivity to environment. It is able to achieve high dynamic range slope measurement without requiring null optics.

    In this dissertation, the sensitivity and performance of the test system have been analyzed comprehensively. Sophisticated calibrations of system components including the geometry, camera and LCD display have been investigated and implemented in different metrology projects to push this technology to a higher accuracy including low-order terms. A compact on-axis SCOTS system lowered the testing geometry sensitivity in the metrology of the 1-meter highly aspheric secondary mirror of the Large Binocular Telescope. Subnanometer accuracy was achieved in testing a high-precision elliptical X-ray mirror by using reference calibration. A well-calibrated SCOTS was successfully constructed and is, at the time of the writing of this dissertation, being used to provide surface metrology feedback for the fabrication of the primary mirror of Daniel K. Inouye Solar Telescope, which is a 4-meter off-axis parabola with a more than 8-millimeter aspherical departure.

    Speaker Bio(s): 

    Run Huang's committee is composed of Jim H. Burge, Hong Hua and Peng Su.