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Proceedings Paper

Laboratory experiment of a high-contrast imaging coronagraph with new step-transmission filters
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Paper Abstract

We present the latest results of our laboratory experiment of the coronagraph with step-transmission filters. The primary goal of this work is to test the stability of the coronagraph and identify the main factors that limit its performance. At present, a series of step-transmission filters has been designed. These filters were manufactured with Cr film on a glass substrate with a high surface quality. During the process of the experiment of each filter, we have identified several contrast limiting factors, which includes the non-symmetry of the coating film, transmission error, scattered light and the optical aberration caused by the thickness difference of coating film. To eliminate these factors, we developed a procedure for the correct test of the coronagraph and finally it delivered a contrast in the order of 10-6~10-7 at an angular distance of 4λD, which is well consistent with theoretical design. As a follow-up effort, a deformable mirror has been manufactured to correct the wave-front error of the optical system, which should deliver better performance with an extra contrast improvement in the order of 10-2~10-3. It is shown that the step-transmission filter based coronagraph is promising for the high-contrast imaging of earth-like planets.

Paper Details

Date Published: 20 August 2009
PDF: 8 pages
Proc. SPIE 7440, Techniques and Instrumentation for Detection of Exoplanets IV, 744019 (20 August 2009); doi: 10.1117/12.825253
Show Author Affiliations
Jiangpei Dou, Nanjing Institute of Astronomical Optics & Technology (China)
Graduate School of the Chinese Academy of Science (China)
Deqing Ren, Nanjing Institute of Astronomical Optics & Technology (China)
California State Univ., Northridge (United States)
Yongtian Zhu, Nanjing Institute of Astronomical Optics & Technology (China)
Xi Zhang, Nanjing Institute of Astronomical Optics & Technology (China)
Graduate School of the Chinese Academy of Science (China)


Published in SPIE Proceedings Vol. 7440:
Techniques and Instrumentation for Detection of Exoplanets IV
Stuart B. Shaklan, Editor(s)

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