Curvature sensing and compensation: a new concept in adaptive optics

Roddier, F.

doi:10.1364/ao.27.001223

Cited by 540 publications

(249 citation statements)

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“…Unfortunately, the most familiar and efficient Wavefront Sensors (WFS) employed in Adaptive Optics are not well matched to that purpose, because they are all based upon WFE slopes or curvature measurements (then reconstructing the wavefronts digitally). Typical examples are the Shack-Hartmann [1], the shearing interferometer [2], the curvature sensor [3] and the most recently proposed pyramidal WFS [4]. Piston evaluation is hardly achievable from these devices, therefore direct phase measurement techniques should be preferred.…”

Section: Introductionmentioning

confidence: 99%

Conceptual design of a phase-shifting telescope-interferometer

Hénault

2006

Optics Communications

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This paper deals with the theoretical principle and optical design of a phase-shifting telescopeinterferometer. What is called a "Telescope-Interferometer" (T-I) is indeed a novel, recently proposed Wavefront Error (WFE) sensing technique, whose basic idea consists in combining the main pupil of a telescope with a second, off-axis reference arm. Then a weak modulation of the Point Spread Function (PSF) is generated at the focal plane, allowing for direct phase measurements. We propose a notable improvement of the method, inspired from classical principles of phase shifting interferometry. Herein are presented the alternative principle and its achievable measurement accuracy. The technique shows high performance excepted on narrow areas located near the pupil boundary. It is applicable to both ground or space telescopes and is suitable for the co-phasing of segmented mirrors, which is of prime importance in view of future giant telescope projects. PACS: 42.30.Kq; 42.30.Rx; 95.55.Cs; 95.55.Fw; 95.75.Qr

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Section: Introductionmentioning

confidence: 99%

Conceptual design of a phase-shifting telescope-interferometer

Hénault

2006

Optics Communications

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“…The PWFS is also less prone to aliasing effects than the SHWFS, although this can be mitigated by the use of an adjustable spatial filter, as in Gemini/GPI and VLT/SPHERE. The curvature WFS (CWFS) uses two out of focus measurements to derive the curvature (second derivative) of the wavefront [26]. It can be implemented by a oscillating membrane.…”

Section: Wavefront Sensingmentioning

confidence: 99%

Adaptive Optics in High-Contrast Imaging

Milli¹,

Mawet²,

Mouillet³

et al. 2016

Astronomy at High Angular Resolution

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The development of adaptive optics (AO) played a major role in modern astronomy over the last three decades. By compensating for the atmospheric turbulence, these systems enable to reach the diffraction limit on large telescopes. In this review, we will focus on high contrast applications of adaptive optics, namely, imaging the close vicinity of bright stellar objects and revealing regions otherwise hidden within the turbulent halo of the atmosphere to look for objects with a contrast ratio lower than 10 −4 with respect to the central star. Such high-contrast AO-corrected observations have led to fundamental results in our current understanding of planetary formation and evolution as well as stellar evolution. AO systems equipped three generations of instruments, from the first pioneering experiments in the nineties, to the first wave of instruments on 8m-class telescopes in the years 2000, and finally to the extreme AO systems that have recently started operations. Along with highcontrast techniques, AO enables to reveal the circumstellar environment: massive protoplanetary disks featuring spiral arms, gaps or other asymetries hinting at ongoing planet formation, young giant planets shining in thermal emission, or tenuous debris disks and micron-sized dust leftover from collisions in massive asteroid-belt analogs. After introducing the science case and technical requirements, we will review the architecture of standard and extreme AO systems, before presenting a few selected science highlights obtained with recent AO instruments.

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“…The angular resolution of large astronomical telescope is limited by the seeing, its influence is much larger in comparison to a diffraction limit. Recently, numerous techniques exist for seeing compensation by means of adaptive optics (Roddier, 1998) active and nowadays also passive. The interesting point of view is the comparison of propagation delay between microwave and optical region.…”

Section: Introductionmentioning

confidence: 99%