12 July 2008 Polarization analysis as a means of detecting exoplanets and measuring their objective spectra
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We present a method of the polarization degree analysis of exoplanets' objective-prism spectra. The polarization analysis of the objective spectra can be used for discerning planet signal from noisy stellar light. The light reflected from the planet is expected to be partially polarized, while the direct stellar light can be considered to be unpolarized. For measuring objective spectra we use a four-quadrant polarization mask (FQPoM) coronagraph and a prism. The primary suppression of starlight is achieved by destructive interference of the light passing through the central region of FQPoM. For further suppression of starlight we use a polarization differential technique. By taking the difference between two orthogonally polarized components of incoming light we can further suppress unpolarized starlight and reveal the spectrum of the exoplanet. However, when the intensity contrast between the star and its planet is high, the starlight noise impedes detection of the planetary spectrum. The analysis of the degree of polarization relieves the separation of the planetary spectrum from the stellar noise. Moreover, any peculiar features in the objective spectra would be useful to find out the location of the exoplanet. We obtained the experimental results under an intensity contrast of 3.5×10-5 and an angular separation of 4.9 λ/D.
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N. Zubko, N. Zubko, N. Baba, N. Baba, N. Murakami, N. Murakami, } "Polarization analysis as a means of detecting exoplanets and measuring their objective spectra", Proc. SPIE 7010, Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter, 70101P (12 July 2008); doi: 10.1117/12.788538; https://doi.org/10.1117/12.788538


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