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Goddard Space Flight Center, Greenbelt, Maryland 20771

photo of Doug Rabin

ENGINEERING COLLOQUIUM

Monday, May 14, 2018 / 3:30 PM, Building 36 Symposium Room

Doug Rabin

"Diffractive Imaging for Milliarcsecond Resolution"

ABSTRACT -- Many interesting astrophysical phenomena are known from observation or inferred from theory to subtend very small angles as seen from Earth, 1‒100 milliarcsecond (where 1 milliarcsecond is 0.000000278 degree). Extreme ultraviolet (EUV) and soft X-ray (SXR) telescopes rarely achieve diffraction-limited performance because conventional reflective optics of the required size typically cannot be manufactured to the required figure accuracy.

Diffractive optics can overcome the angular-resolution limitations of EUV/SXR mirrors but present other design and performance challenges. A diffractive telescope is well-suited for probing for the first time the expected energy dissipation scales of the solar corona (less than or equal to 30 km or 40 milliarcsecond as seen from Earth).

This talk will explore the scientific motivation for milliarcsecond angular resolution and explain how diffractive optics can achieve this goal. State-of-the-art examples of diffractive optics will be shown, including photon sieves and Fresnel zone plates fabricated by a Goddard team. The path to a diffractive optics science mission runs through increased optical efficiency, larger aperture, and precision formation flying, all under active development.

SPEAKER -- Doug Rabin is a research astrophysicist in GSFC's Heliophysics Science Division, where he studies the solar corona and develops instruments to characterize it. He received his Ph.D. from the California Institute of Technology and subsequently worked at the University of Cambridge, MSFC, and the National Solar Observatory. He led the Solar Physics Laboratory for 10 years after joining Goddard in 2001.

Engineering Colloquium home page: https://ecolloq.gsfc.nasa.gov