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Filtering by: Creator Zhu, Yongtian Remove constraint Creator: Zhu, Yongtian

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  • Nc580q788?file=thumbnail
    Article
    Dou, Jiangpei
    Wavefront sensing from multiple focal plane images is a promising technique for high-contrast imaging systems. However, the wavefront error of an optics system can be properly reconstructed only when it is very small. This paper presents an iterative . . .
  • D791sk78b?file=thumbnail
    Article
    Dou, Jiangpei
    We propose a transmission-filter coronagraph for direct imaging of Jupiter-like exoplanets with ground-based telescopes. The coronagraph is based on a transmission filter that consists of finite number of transmission steps. A discrete optimization al . . .
  • Work
    Article
    Dou, Jiangpei
    Characterization of day-time atmospheric turbulence profiles up to 30 km above the telescope is crucial for designs and performance estimations of future solar multiconjugate adaptive optics (MCAO) systems. Recently, the S-DIMM+ method has been succes . . .
  • 9p290d84n?file=thumbnail
    Article
    Zhu, Yongtian
    The high-contrast coronagraph for direct imaging earth-like exoplanet at the visible needs a contrast of 10^-10 at a small angular separation of 4Y/D or less. Here we report our recent laboratory experiment that is close to the limits. The test of the . . .
  • Work
    Article
    Zhu, Yongtian
    Using an optical vortex coronagraph (OVC) is one of the most promising techniques for directly imaging exoplanets because of its small inner working angle and high throughput. This paper presents the design and laboratory demonstration performance of . . .
  • Work
    Article
    Zhu, Yongtian
    Almost all high-contrast imaging coronagraphs proposed until now are based on passive coronagraph optical components. That is, the coronagraph cannot be actively controlled to be optimized for best performance. Pupil apodizing, which modifies the ligh . . .
  • Ft848v09h?file=thumbnail
    Article
    Zhu, Yongtian
    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 propo . . .
  • 2n49t495j?file=thumbnail
    Article
    Dou, Jiangpei
    High-contrast imaging provided by a coronagraph is critical for the direction imaging of the Earth-like planet orbiting its bright parent star. A major limitation for such direct imaging is the speckle noise that is induced from the wave-front error o . . .
  • Work
    Article
    Mishmash, Ryan V.
    Solar conventional adaptive optics (CAO) with one deformable-mirror uses a small field-of-view (FOV) for wave-front sensing, which yields a small corrected FOV for high-resolution imaging. Solar activities occur in a two-dimensional extended FOV and s . . .
  • Work
    Article
    Zhu, Yongtian
    We propose a coronagraph for direct imaging of Earth‐like planets orbiting nearby bright stars. The coronagraph is based on an apodization pupil composed of two stepped‐transmission filters. We show that the coronagraph can achieve 10−10 high‐contrast . . .