摘要
The light reflected from planets is polarized mainly due to Rayleigh scattering, but starlight is normally unpolarized. Thus it provides an approach to enhance the imaging contrast by inducing the imaging polarimetry technique. In this paper, we propose a high-contrast imaging polarimeter that is op- timized for the direct imaging of exoplanets, combined with our recently developed stepped-transmission filter based coronagraph. Here we present the design and calibration method of the polarimetry system and the associated test of its high-contrast performance. In this polarimetry system, two liquid crystal variable retarders （LCVRs） act as a polarization modulator, which can extract the polarized signal. We show that our polarimeter can achieve a measurement accuracy of about 0.2% at a visible wavelength （632.8 nm） with linearly polarized light. Finally, the whole system demonstrates that a contrast of 10 9 at 5A/D is achievable, which can be used for direct imaging of Jupiter-like planets with a space telescope.
The light reflected from planets is polarized mainly due to Rayleigh scattering, but starlight is normally unpolarized. Thus it provides an approach to enhance the imaging contrast by inducing the imaging polarimetry technique. In this paper, we propose a high-contrast imaging polarimeter that is op- timized for the direct imaging of exoplanets, combined with our recently developed stepped-transmission filter based coronagraph. Here we present the design and calibration method of the polarimetry system and the associated test of its high-contrast performance. In this polarimetry system, two liquid crystal variable retarders （LCVRs） act as a polarization modulator, which can extract the polarized signal. We show that our polarimeter can achieve a measurement accuracy of about 0.2% at a visible wavelength （632.8 nm） with linearly polarized light. Finally, the whole system demonstrates that a contrast of 10 9 at 5A/D is achievable, which can be used for direct imaging of Jupiter-like planets with a space telescope.
基金
supported by the NSFC(Grant Nos.11220101001,11433007,11328302,11373005 and 11303064)
the“Strategic Priority Research Program”of the Chinese Academy of Sciences(Grant Nos.XDA04070600 and XDA04075200)
the special funding for Young Researchers of Nanjing Institute of Astronomical Optics&Technology
the special fund for astronomy(Grant No.KT2013-022)of CAS.
carried out at California State University Northridge,with support from the Mt.Cuba Astronomical Foundation
