Direct imaging of exoplanets by reflected starlight is extremely challenging due to the large luminosity ratio to the primary star. Wave-front control is a critical technique to attenuate the speckle noise in order to achieve an extremely high contras . . .

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 . . .

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 . . .

Image Rotation and Subtraction (IRS) is a high-contrast imaging technique that can be used to suppress the speckle noise and facilitate the direct detection of exoplanets. IRS is different from Angular Differential Imaging (ADI), in that it will subtr . . .

We present a novel "spectral subtraction algorithm" (SSA) technique to remove speckle noise. It consists of a low-order and a high-order SSA and is based on a three-dimensional image spectroscopy in which the three-dimensional data cube is available a . . .

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 . . .

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 . . .

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 . . .

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 . . .

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 . . .