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We review the systematic uncertainties that have plagued attempts to obtain high precision and high accuracy from ground-based photometric measurements using CCDs. We identify two main challenges in breaking through the 1% precision…

Astrophysics · Physics 2008-11-26 Christopher W. Stubbs , John L. Tonry

Very high dynamical range coronagraphs targeting direct exo-planet detection (10^9 - 10^10 contrast) at small angular separation (few lambda/D units) usually require an input wavefront quality on the order of ten thousandths of wavelength…

Astrophysics · Physics 2009-11-13 J. Nishikawa , L. Abe , N. Murakami , T. Kotani

The Optimal Optical CoronagraphWorkshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas.…

Focal plane wavefront sensing is an elegant solution for wavefront sensing since near-focal images of any source taken by a detector show distortions in the presence of aberrations. Non-Common Path Aberrations and the Low Wind Effect both…

Adaptive optic (AO) systems delivering high levels of wavefront correction are now common at observatories. One of the main limitations to image quality after wavefront correction comes from atmospheric refraction. An Atmospheric dispersion…

Instrumentation and Methods for Astrophysics · Physics 2018-01-31 Prashant Pathak , Olivier Guyon , Nemanja Jovanovic , Julien Lozi , Frantz Martinache , Yosuke Minowa , Tomoyuki Kudo , Takayuki Kotani , Hideki Takami

It has previously been demonstrated in both simulation and experiment that well aligned remote focusing microscopes exhibit residual spherical aberration outside the focal plane. In this work, compensation of the residual spherical…

Optics · Physics 2023-05-17 Sharika Mohanan , Alexander D. Corbett

Regressing the illumination of a scene from the representations of object appearances is popularly adopted in computational color constancy. However, it's still challenging due to intrinsic appearance and label ambiguities caused by unknown…

Computer Vision and Pattern Recognition · Computer Science 2019-12-25 Huanglin Yu , Ke Chen , Kaiqi Wang , Yanlin Qian , Zhaoxiang Zhang , Kui Jia

The direct detection of extrasolar planets by imaging means is limited by the large flux of light from the host star being scattered into the region of interest by a variety of processes, including diffraction. Coronagraphs are devices that…

Astrophysics · Physics 2009-11-10 James P. Lloyd , Anand Sivaramakrishnan

Due to the imbalanced and limited data, semi-supervised medical image segmentation methods often fail to produce superior performance for some specific tailed classes. Inadequate training for those particular classes could introduce more…

Computer Vision and Pattern Recognition · Computer Science 2022-09-02 Hritam Basak , Sagnik Ghosal , Ram Sarkar

State-of-the-art coronagraphs employed on extreme adaptive optics enabled instruments, are constantly improving the contrast detection limit for companions at ever closer separations to the host star. In order to constrain their properties…

Instrumentation and Methods for Astrophysics · Physics 2015-11-11 Nemanja Jovanovic , Olivier Guyon , Frantz Martinache , Prashant Pathak , Janis Hagelberg , Tomoyuki Kudo

The complete characterization of spatial coherence is difficult because the mutual coherence function is a complex-valued function of four independent variables. This difficulty limits the ability of controlling and optimizing spatial…

The behavior of an adaptive optics (AO) system for ground-based high contrast imaging (HCI) dictates the achievable contrast of the instrument. In conditions where the coherence time of the atmosphere is short compared to the speed of the…

Instrumentation and Methods for Astrophysics · Physics 2021-08-23 Maaike A. M. van Kooten , Rebecca Jensen-Clem , Sylvain Cetre , Sam Ragland , Charlotte Z. Bond , J. Fowler , Peter Wizinowich

High contrast imaging (HCI) systems rely on active wavefront control (WFC) to deliver deep raw contrast in the focal plane, and on calibration techniques to further enhance contrast by identifying planet light within the residual speckle…

An adaptive optics (AO) system based on stochastic parallel gradient descent (SPGD) algorithm is proposed to reduce the speckle noises in the optical system of stellar coronagraph in order to further improve the contrast. The principle of…

Instrumentation and Methods for Astrophysics · Physics 2015-05-28 Bing Dong , Deqing Ren , Xi Zhang

High-contrast imaging in the next decade aims to image exoplanets at smaller angular separations and deeper contrasts than ever before. A problem that has recently garnered attention for telescopes equipped with high-contrast coronagraphs…

Instrumentation and Methods for Astrophysics · Physics 2024-07-01 Jaren N. Ashcraft , Ewan S. Douglas , Ramya M. Anche , Kyle Van Gorkom , Emory Jenkins , William Melby , Maxwell A. Millar-Blanchaer

A power constrained sensor network that consists of multiple sensor nodes and a fusion center (FC) is considered, where the goal is to estimate a random parameter of interest. In contrast to the distributed framework, the sensor nodes may…

Information Theory · Computer Science 2012-07-03 Swarnendu Kar , Pramod K. Varshney

The problem of self-calibration of two cameras from a given fundamental matrix is one of the basic problems in geometric computer vision. Under the assumption of known principal points and square pixels, the well-known Bougnoux formula…

Computer Vision and Pattern Recognition · Computer Science 2025-11-07 Viktor Kocur , Daniel Kyselica , Zuzana Kukelova

The optical vortex coronagraph is potentially a remarkably effective device, at least for an ideal unobstructed telescope. Most ground-based telescopes however suffer from central obscuration and also have to operate through the aberrations…

Astrophysics · Physics 2009-11-13 Charles Jenkins

The Santa Cruz Extreme AO Lab (SEAL) testbed is an optical bench meant to design and develop new wavefront control techniques for high-contrast imaging for segmented telescopes. These techniques allow for astronomical efficiency in…

Instrumentation and Methods for Astrophysics · Physics 2024-08-14 Ashai Moreno , Vincent Chambouleyron , Rebecca M. Jensen-Clem , Daren Dillon , Philip M. Hinz , Bruce Macintosh

Context: The detection and characterization of Earth-like exoplanets (exoEarths) from space requires exquisite wavefront stability at contrast levels of $10^{-10}$. On segmented telescopes in particular, aberrations induced by cophasing…

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