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A laboratory demonstration of the capability to image an Earth-like extrasolar planet


The detection and characterization of an Earth-like planet orbiting a nearby star requires a telescope with an extraordinarily large contrast at small angular separations. At visible wavelengths, an Earth-like planet would be 1 × 10-10 times fainter than the star at angular separations of typically 0.1 arcsecond or less1,2. There are several proposed space telescope systems that could, in principle, achieve this3,4,5,6. Here we report a laboratory experiment that reaches these limits. We have suppressed the diffracted and scattered light near a star-like source to a level of 6 × 10-10 times the peak intensity in individual coronagraph images. In a series of such images, together with simple image processing, we have effectively reduced this to a residual noise level of about 0.1 × 10-10. This demonstrates that a coronagraphic telescope in space could detect and spectroscopically characterize nearby exoplanetary systems, with the sensitivity to image an ‘Earth-twin’ orbiting a nearby star.

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Figure 1: Representative coronagraph images and intensity profiles.
Figure 2: Laboratory images demonstrate contrast at levels required to detect an Earth-twin.


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The speckle nulling algorithm is due to C. Burrows. Development of the HCIT facility is an ongoing activity. Experiments were designed and simulated with the computational models of D. Moody. The HCIT control system was developed by B. Gordon and A. Niessner. Recent speckle nulling runs in white light have been carried out by B. Kern. The optical alignments were carried out by F. Shi and A. Kuhnert. The DM was manufactured by Xinetics Inc. The coronagraph mask was fabricated under the supervision of D. Wilson at JPL’s Micro Devices Laboratory, on glass substrates supplied by Canyon Materials Inc. This work was carried out at JPL with the support of JPL and NASA.

Author Contributions J.T.T. performed HCIT experiments and data analysis at JPL; J.T.T. and W.A.T. co-wrote the paper.

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Correspondence to John T. Trauger.

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This file contains Supplementary Discussion, Supplementary Figures 1-2 with Legends, Supplementary Table 1 and additional references. (PDF 2207 kb)

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Trauger, J., Traub, W. A laboratory demonstration of the capability to image an Earth-like extrasolar planet. Nature 446, 771–773 (2007).

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