High-contrast imaging coronagraphs, used for the detection of exoplanets, have always adopted passive coronagraph optical components. It is therefore impossible to actively optimize the coronagraphs to achieve their best performance. To solve this problem, we propose a novel high-contrast imaging coronagraph which combines a liquid crystal array (LCA) for active pupil apodization and a deformable mirror (DM) for phase correction. The LCA we use is an amplitude-only spatial light modulator. The LCA is well calibrated and compensates for its amplitude non-uniformity and nonlinear intensity responsivity.We measured the imaging contrasts of the coronagraph system with the LCA only and without the DMdeployed. Imaging contrasts of 10-4and 10-5can be reached at an inner working angular distance of 2.5 and 5/D, respectively. A simulation shows that the phase errors on the coronagraph pupil limit the contrast performance. The contrast could be further improved if a DM is deployed to correct the phase errors induced by the LCA and coronagraph optics.
Xi Zhang,De-Qing Ren,Yong-Tian Zhu,et al. An active coronagraph using a liquid crystal array for exoplanet imaging: principle and testing[J]. Research in Astronomy and Astrophysics,2012,12(5):591–600.
Xi Zhang,De-Qing Ren,Yong-Tian Zhu,&Jiang-Pei Dou.(2012).An active coronagraph using a liquid crystal array for exoplanet imaging: principle and testing.Research in Astronomy and Astrophysics,12(5),591–600.
Xi Zhang,et al."An active coronagraph using a liquid crystal array for exoplanet imaging: principle and testing".Research in Astronomy and Astrophysics 12.5(2012):591–600.