Programm
Aeronautical Metrology
Dr. William Zhang
NASA Goddard Space Flight Center - USA
Resumen de la ponencia
The International X-ray Observatory (IXO) is the next major space X-ray observatory, performing both imaging and spectroscopic studies of all kinds of objects in the Universe. It is a collaborative mission of the National Aeronautics and Space Administration of the United States, the European Space Agency, and Japan Aerospace Exploration Agency. It is to be launched into a Sun-Earth L2 orbit in 2021. One of the most challenging aspects of the mission is the construction of a flight mirror assembly capable focusing X-rays in the band of 0.1 to 40 keV with an angular resolution of better than 5 arc-seconds and with an effective collection area of more than 3 m2. The mirror assembly will consist of approximately 15,000 parabolic and hyperbolic mirror segments, each of which is approximately 200mm by 300mm with a thickness of 0.4mm. The manufacture and qualification of these mirror segments and their integration into the giant mirror assembly have been the objectives of a vigorous technology development program at NASA’s Goddard Space Flight Center. Each of these mirror segments needs to be measured and qualified for both optical figure and mechanical dimensions. In this talk, I will describe the technology program with a particular emphasis on a measurement system we are developing to meet those requirements, including the use of coordinate measuring machines, Fizeau interferometers, and custom-designed, and –built null lens. This system is capable of measuring highly off-axis aspherical or cylindrical mirrors with repeatability, accuracy, and speed.
Información sobre el ponente
William Zhang got his PhD from the University of Pennsylvania, working on the detection of neutrinos from supernovae and the Sun. After spending 2 years at the Los Alamos National Laboratory where he was responsible for constructing, calibrating, and commissioning a large air shower array, he joined the scientific staff at NASA Goddard Space Flight Center in 1991 where he has been since. Between 1992 and 1997 he was an instrument scientist responsible for the construction and calibration of the proportional counter array onboard the Rossi X-ray Timing Explorer which has been in orbit since late 1995. Around 2000 his interests shifted from detector to X-ray optics. He has been leading a group of scientists and engineers to develop the necessary technique to construct the largest X-ray telescope, the International X-ray Observatory (IXO). He will talk about IXO and his optics work today.