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Proceedings Paper

Laboratory experiment of a coronagraph based on step-transmission filters
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Paper Abstract

This paper presents the first results of a step-transmission-filter based coronagraph in the visible wavelengths. The primary goal of this work is to demonstrate the feasibility of the coronagraph that employs step-transmission filters, with a required contrast in the order of better than 10-5 at an angular distance larger than 4λ/D. Two 13-step-transmission filters were manufactured with 5% transmission accuracy. The precision of the transmitted wave distortion and the coating surface quality were not strictly controlled at this time. Although in perfect case the coronagraph can achieve theoretical contrast of 10-10, it only delivers 10-5 contrast because of the transmission error, poor surface quality and wave-front aberration stated above, which is in our estimation. Based on current techniques, step-transmission filters with better coating surface quality and high-precision transmission can be made. As a follow-up effort, high-quality step-transmission filters are being manufactured, which should deliver better performance. The step-transmission-filter based coronagraph has the potential applications for future high-contrast direct imaging of earth-like planets.

Paper Details

Date Published: 12 July 2008
PDF: 10 pages
Proc. SPIE 7010, Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter, 70104J (12 July 2008); doi: 10.1117/12.785491
Show Author Affiliations
Jiangpei Dou, National Astronomical Observatories, Nanjing Institute of Astronomical Optics and Technology (China)
Graduate School of the Chinese Academy Science (China)
Yongtian Zhu, National Astronomical Observatories, Nanjing Institute of Astronomical Optics and Technology (China)
Deqing Ren, National Astronomical Observatories, Nanjing Institute of Astronomical Optics and Technology (China)
California State Univ., Northridge (United States)
Xi Zhang, National Astronomical Observatories, Nanjing Institute of Astronomical Optics and Technology (China)
Graduate School of the Chinese Academy Science (China)


Published in SPIE Proceedings Vol. 7010:
Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter
Jacobus M. Oschmann; Mattheus W. M. de Graauw; Howard A. MacEwen, Editor(s)

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