Download or read book Special Issue on Adaptive Optics Control for Ground Based Telescopes written by Caroline Kulcsár and published by . This book was released on 2011 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Adaptive Optics written by Robert K. Tyson and published by SPIE Press. This book was released on 2000 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive optics systems and components have achieved a level of sophistication and simplicity that goes beyond traditional applications in astronomy and the military and into developments in medicine, manufacturing, and communications. This book was written for those interested in the multidisciplinary technology and those who need a broad-brush explanation without wading through thousands of journal articles. It follows the structure of a one-day tutorial taught by the author, including humor and sidebars of historical material.
Download or read book Adaptive Optics for Astronomy written by D.M. Alloin and published by Springer Science & Business Media. This book was released on 1994-03-31 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: The blossoming of adaptive optical techniques has brought about a revolution in the field of astronomical observation. Coupled with the new generation of large, ground-based telescopes, it allows us to achieve an unprecendented angular resolution in the analysis of faint astronomical sources at optical wavelengths. This book provides the basic concepts of adaptive optics, discusses the possible instrumental strategies and the state-of-the-art technical achievements of this development and presents the key astrophysical programs which will most benefit from it. Over fifteen well-known experts have contributed to making this volume a comprehensive one, with steady progression as well as full coverage of the various aspects of the field. Students graduating in optical sciences and astrophysics, astronomers, engineers interested in atmospheric turbulence compensation will find this book a reference text on the subject.
Download or read book Selected Papers on Adaptive Optics for Atmospheric Compensation written by James E. Pearson and published by SPIE-International Society for Optical Engineering. This book was released on 1994 with total page 748 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamic Reconstruction and Multivariable Control for Force Actuated Thin Facesheet Adaptive Optics written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-11-18 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Multiple Mirror Telescope (MMT) under development at the University of Arizona takes a new approach in adaptive optics placing a large (0.65 m) force-actuated, thin facesheet deformable mirror at the secondary of an astronomical telescope, thus reducing the effects of emissivity which are important in IR astronomy. However, The large size of the mirror and low stiffness actuators used drive the natural frequencies of the mirror down into the bandwidth of the atmospheric distortion. Conventional adaptive optics takes a quasi-static approach to controlling the, deformable mirror. However, flexibility within the control bandwidth calls for a new approach to adaptive optics. Dynamic influence functions are used to characterize the influence of each actuator on the surface of the deformable mirror. A linearized model of atmospheric distortion is combined with dynamic influence functions to produce a dynamic reconstructor. This dynamic reconstructor is recognized as an optimal control problem. Solving the optimal control problem for a system with hundreds of actuators and sensors is formidable. Exploiting the circularly symmetric geometry of the mirror, and a suitable model of atmospheric distortion, the control problem is divided into a number of smaller decoupled control problems using circulant matrix theory. A hierarchic control scheme which seeks to emulate the quasi-static control approach that is generally used in adaptive optics is compared to the proposed dynamic reconstruction technique. Although dynamic reconstruction requires somewhat more computational power to implement, it achieves better performance with less power usage, and is less sensitive than the hierarchic technique. Grocott, Simon C. O. and Miller, David W. Langley Research Center; Marshall Space Flight Center ADAPTIVE OPTICS; DEFORMABLE MIRRORS; TELESCOPES; DYNAMIC CONTROL; OPTIMAL CONTROL; ACTUATORS; ATMOSPHERIC MODELS; BANDWIDTH; DISTORTION; EMISSIVITY; FLEXIBILITY; INFRARED ASTRONOMY; MATRI...
Download or read book Adaptive Optics for Astronomical Telescopes written by John W. Hardy and published by Oxford Optical and Imaging Sci. This book was released on 1998 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book by one of the leaders in adaptive optics covers the fundamental theory and then describes in detail how this technology can be applied to large ground-based telescopes to compensate for the effects of atmospheric turbulence. It includes information on basic adaptive optics components and technology, and has chapters devoted to atmospheric turbulence, optical image structure, laser beacons, and overall system design. The chapter on system design is particularly detailed and includes performance estimation and optimization. Combining a clear discussion of physical principles with numerous real-world examples, this book will be a valuable resource for all graduate students and researchers in astronomy and optics.
Download or read book Adaptive Optics in Astronomy written by François Roddier and published by Cambridge University Press. This book was released on 1999-06-17 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive optics is set to revolutionise the future of astronomy; this is the first book on the subject and is set to become the standard reference.
Download or read book Wavefront Control for Space Telescope Applications Using Adaptive Optics written by and published by . This book was released on 2007 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: Future long dwell high resolution imagery satellites and space telescopes will require very large flexible primary mirrors. These large mirrors face many challenges including optical surface imperfections, structural vibrations, and jitter. A flexible mirror can overcome some of these challenges by applying adaptive optics techniques to correct mirror deformations and aberrations to produce image quality data. This paper examines and develops control techniques to control a deformable mirror subjected to a disturbance. The experimental portion of the work uses discrete time proportional integral control with second order filters to control disturbances in a deformable mirror and correct aberrations in an adaptive optics system using laser light. Using an adaptive optics testbed containing two deformable mirrors, two fast steering mirrors, two wave front sensors, a position sensor, and a combination of lenses the system corrects a simulated dynamic disturbance induced in the deformable mirror. Experiments using the described testbed successfully demonstrate wavefront control methods, including a combined iterative feedback and gradient control technique. This control technique results in a three fold improvement in RMS wavefront error over the individual controllers correcting from a biased mirror position. Second order discrete time notch filters are also used to remove induced low frequency actuator and sensor noise at 0.8 Hz, 2 Hz and 5 Hz. Additionally a 2 Hz structural disturbance is simulated on a Micromachined Membrane Deformable Mirror and removed using discrete time notch filters combined with a modal iterative closed loop feedback controller, showing a 36 fold improvement in RMS wavefront error over the iterative closed loop feedback alone.
Download or read book Distributed Control of a Retinal Imaging Adaptive Optics System written by Maurizio Ficocelli and published by . This book was released on 2008 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years a technique known as adaptive optics (AO), commonly used to correct the dynamic wavefront error caused by atmospheric turbulence in ground-based telescopes, has been studied as a means of correcting the dynamic wavefront error caused by aberrations in the human eye, allowing for higher resolution retinal images. In order to compensate for these dynamic aberrations, a compact AO system that tracks and compensates for these changes in real-time is needed. To realize such a system, improvements must be made in two key components, namely the control algorithms and the design of the wavefront corrector. The latter represents the main focus of this thesis. The control problem in adaptive optics systems is generalized to that of shape control for a flexible membrane representing a deformable membrane mirror used in the wavefront corrector. Due to the dynamic nature of the aberrations in the eye, the shape control problem addressed is the tracking of an unknown and time-varying shape for a distributed membrane (i.e., desired shape of the mirror). The proposed controller design approach relies on two steps. The first step is to construct a Q -parameterized set of stabilizing controllers for the system under consideration and to derive conditions on the Q parameter in the controller expression to achieve regulation. Since the desired shape of the mirror is unknown and time-varying, the second step is to derive an online tuning algorithm for the Q parameter in the expression for the parameterized stabilizing controller. The online tuning of the Q parameter allows the controller to converge to the controller needed to achieve regulation, hence compensating for the lack of information on the desired shape for the deformable mirror. Decoupling introduced in the closed loop system allows tuning to be performed using decentralized algorithms.
Download or read book Tractability of Complex Control Systems written by Laurent Alexis Dewhirst Lessard and published by Stanford University. This book was released on 2011 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is divided into two main parts. In the first part, we consider the problem of efficiently computing wavefront estimates for use in adaptive optics hardware on ground-based telescopes. Our contribution is a warm-started single-iteration multigrid algorithm that performs as well as conventional vector-matrix-multiplication methods, but at a fraction of the computational cost. We used numerical simulations to compare our algorithm to a variety of other published methods, and validated our findings at the Palomar Observatory. In the second part, we consider feedback control subject to an information constraint. Using a novel algebraic framework, we are able to prove many structural results, including a new convexity result, in a natural and purely algebraic way. We also develop a new condition we call internal quadratic invariance, under which the controller synthesis can be cast as a convex optimization problem. This describes the most general class of tractable decentralized control problems known to date. Both parts of the thesis fit into the broader question of tractability of complex systems. In the first part we look at a practical example which is difficult because of the large number of sensors and actuators. In the second part, we look at decentralized control, which is difficult because of the non-classical information constraint.
Download or read book Principles Of Adaptive Optics written by Robert Tyson and published by Academic Press. This book was released on 2012-12-02 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: Principles of Adaptive Optics covers the basic principles of optics, wavefront sensing, controls, and wavefront correction that encompass the specialized field called adaptive optics. This book is composed of eight chapters that summarize the fundamental technology developments and the basic understanding of the various disciplines used in adaptive optics. After briefly reviewing the history, background, and developments of adaptive optics, this book goes on discussing the many sources of phase aberrations addressed by adaptive optics systems, such as linear effects due to turbulence, optical manufacturing, and misalignments, as well as errors that result from nonlinear thermal effects and fluid properties. The subsequent chapter deals with the performance enhancing role of adaptive optics systems in various disturbances. Other chapters describe the wavefront sampling, sensing, and correction subsystems. The concluding chapters explore the fundamental principles behind the adaptive optics control system and present summary expressions to determine the basic system parameters of an adaptive optics atmospheric compensation system. Communication scientists and engineers will find this work invaluable.
Download or read book Program Solicitation written by and published by . This book was released on 1995 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Issues in Systems Engineering 2013 Edition written by and published by ScholarlyEditions. This book was released on 2013-05-01 with total page 585 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Systems Engineering / 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Systems and Control Engineering. The editors have built Issues in Systems Engineering: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Systems and Control Engineering in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Systems Engineering: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book Principles of Adaptive Optics written by Robert Tyson and published by CRC Press. This book was released on 2010-09-14 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the publication of the second edition of Principles of Adaptive Optics, the developments and applications in this area have increased tremendously. Observatories are now producing outstanding science through adaptive optics technology; components, such as micromachined deformable mirrors and very low noise detectors, are revolutionizing the f
Download or read book Ground Based Astronomy with Adaptive Optics written by Stephen Thurman Ridgway and published by . This book was released on 1998 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Keck Adaptive Optics written by and published by . This book was released on 1996 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive optics on the Keck 10 meter telescope will provide an unprecedented level of capability in high resolution ground based astronomical imaging. The system is designed to provide near diffraction limited imaging performance with Strehl
Download or read book Adaptive Optics for Astronomy written by D.M. Alloin and published by Springer. This book was released on 2010-12-04 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: For many astronomers, Adaptive Optics is something like a dream coming true. Sinee 1609 and the first observations of celestial bodies performed with the help of an optieal teleseope, astronomers have always fighted to improve the 'resolving power' of their instruments. For a long time, engineers have trimmed the optieal quality of the teleseopes, until they finally reaehed the barrier set by the atmospherie turbulence, a few seconds of are. At that point, the intrinsic quality of the site beeame a major issue to establish new observatories with modern telescopes, and astronomers started to desert the urban skies and to migrate toward mountains and deserts. This quest has been sueeessful and a few privileged sites, where the average natural 'seeing' is close to 0. 5", are now hosting clusters of giant telescopes of the 4 m and soon 10 m class. Yet, this atmospherie limit corresponds in the visible wavelength range to the diffraetion limit of a 20 em telescope only. The loss was severe: a faetor 20 in angular and several hundred in peak energy eoncentration, i. e. in deteetivity of resolution very faint objeets. In the beginning of the seventies, two doors half opened to provide a way out of this dead-end. First, the technique of speckle interferometry (and its various related developments) has allowed to restore the diffraetion limit of large telescopes at visible and infrared wavelengths (see, e. g.
