Related papers: Low-order wavefront control using a Zernike sensor…

The Low Wind Effect (LWE) refers to a phenomenon that occurs when the wind speed inside a telescope dome drops below $3$m/s creating a temperature gradient near the telescope spider. This produces phase discontinuities in the pupil plane…

We conducted a number of multi-band coronagraph experiments using a vacuum chamber and a binary-shaped pupil mask which in principle should work at all wavelengths, in the context of the research and development on a coronagraph to observe…

Extra-solar planets direct imaging is now a reality with the deployment and commissioning of the first generation of specialized ground-based instruments (GPI, SPHERE, P1640 and SCExAO). These systems allow of planets $ 10 ^ 7 $ times…

Due to turbulence in the atmosphere images taken from ground-based telescopes become distorted. With adaptive optics (AO) images can be given greater clarity allowing for better observations with existing telescopes and are essential for…

Astronomers working with faint targets will benefit greatly from improved image quality on current and planned ground-based telescopes. At present, most adaptive optic systems are targeted at the highest resolution with bright guide stars.…

Direct imaging of Earth-like planets from space requires dedicated observatories, combining large segmented apertures with instruments and techniques such as coronagraphs, wavefront sensors, and wavefront control in order to reach the high…

Several Extreme Adaptive Optics (XAO) systems dedicated to the detection and characterisation of the exoplanets are currently in operation for 8-10 meter class telescopes. Coronagraphs are commonly used in these facilities to reject the…

High-order wavefront sensing and control (HOWFSC) is key to create a dark hole region within the coronagraphic image plane where high contrasts are achieved. The Roman Coronagraph is expected to perform its HOWFSC with a ground-in-the-loop…

Potentially habitable planets around nearby stars less massive than solar-type stars could join targets of the spectroscopy of the planetary reflected light with future space telescopes. However, the orbits of most of these planets occur…

A high contrast coronagraph is expected to provide one of the promising ways to directly observe extra-solar planets. We present the newest results of our laboratory experiment investigating "rigid" coronagraph with a binary shaped…

Direct exoplanet imaging via coronagraphy requires maintenance of high contrast in a dark hole for lengthy integration periods. Wavefront errors that change slowly over that time accumulate and cause systematic errors in the star's Point…

Direct imaging of exoplanets relies on complex wavefront sensing and control architectures. In addition to fast adaptive optics systems, most of the future high-contrast imaging instruments will soon be equipped with focal plane wavefront…

Context: High contrast imaging is a powerful technique to detect and characterize planetary companions at large orbital separations from their parent stars. Aims: We aim at studying the limiting magnitude of the VLT/SPHERE Adaptive Optics…

Adaptive optics (AO) is critical in astronomy, optical communications and remote sensing to deal with the rapid blurring caused by the Earth's turbulent atmosphere. But current AO systems are limited by their wavefront sensors, which need…

Directly imaging Earth-like exoplanets (``exoEarths'') with a coronagraph instrument on a space telescope requires a stable wavefront with optical path differences limited to tens of picometers RMS during exposure times of a few hours.…

The search for exoplanets is pushing adaptive optics systems on ground-based telescopes to their limits. One of the major limitations at small angular separations, exactly where exoplanets are predicted to be, is the servo-lag of the…

Aims. We present a solution to improve the performance of coronagraphs for the detection of exo-planets. Methods. We simulate numerically several kinds of coronagraphic systems, with the aim of evaluating the gain obtained with an adaptive…

Ground-based high contrast exoplanet imaging requires state-of-the-art adaptive optics (AO) systems in order to detect extremely faint planets next to their brighter host stars. For such extreme AO systems (with high actuator count…

The Apodized Pupil Lyot Coronagraph (APLC) is a diffraction suppression system installed in the recently deployed instruments Palomar/P1640, Gemini/GPI, and VLT/SPHERE to allow direct imaging and spectroscopy of circumstellar environments.…

Ground-based high contrast imaging (HCI) and extreme adaptive optics (AO) technologies have advanced to the point of enabling direct detections of gas-giant exoplanets orbiting beyond the snow lines around nearby young star systems.…