Download or read book Diffraction limited Imaging With Large And Moderate Telescopes written by Swapan K Saha and published by World Scientific. This book was released on 2007-06-20 with total page 633 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with the fundamentals of wave optics, polarization, interference, diffraction, imaging, and the origin, properties, and optical effects of turbulence in the Earth's atmosphere. Techniques developed during the last few decades to overcome atmospheric image degradation (including passive methods, speckle interferometry in particular, and active methods such as adaptive optics), are highlighted. Also discussed are high resolution sensors, image processing, and the astronomical results obtained with these techniques.
Download or read book Diffraction limited Imaging with Astronomical Telescopes written by Keith Thomas Knox and published by . This book was released on 1975 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Diffraction Limited Imaging with Very Large Telescopes written by D.M. Alloin and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt: A few years ago, a real break-through happened in observational astronomy: the un derstanding of the effect of atmospheric turbulence on the structure of stellar images, and of ways to overcome this dramatic degradation. This opened a route to diffraction-limited observations with large telescopes in the optical domain. Soon, the first applications of this new technique led to some outstanding astrophysical results, both at visible and infrared wavelengths. Yet, the potential of interferometric observations is not fully foreseeable as the first long-baseline arrays of large optical telescopes are being built or cOIIllnissioned right now. In this respect a comparison with the evolution of radio-astronomy is tempting. From a situation where, in spite of the construction of giant antennas, low angular resolution was prevailing, the introduction of long baseline and very long baseline interferometry and the rapid mastering of sophisticated image reconstruction techniques, have brought on a nearly routine basis high dynamic range images with milliarcseconds resolution. This, of course, has completely changed our views of the radio sky.
Download or read book Lucky Exposures written by Robert Nigel Tubbs and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The resolution of astronomical imaging from large optical telescopes is usually limited by the blurring effects of refractive index fluctuations in the Earth's atmosphere. By taking a large number of short exposure images through the atmosphere, and then selecting, re-centring and co-adding the best images this resolution limit can be overcome. This approach has significant benefits over other techniques for high-resolution optical imaging from the ground. In particular the reference stars used for our method (the Lucky Exposurestechnique) can generally be fainter than those required for the natural guide staradaptive optics approach or those required for other speckle imaging techniques. The lowcomplexity and low instrumentation costs associated with the Lucky Exposures methodmake it appealing for medium-sized astronomical observatories. The method can provide essentially diffraction-limited I-band imaging from well-figuredground-based telescopes as large as 2.5 m diameter. The faint limiting magnitude and large isoplanatic patch size for the Lucky Exposures technique at the Nordic Optical Telescope means that 25% of the night sky is within range of a suitable reference star for I-band imaging. Typically the 1%-10% of exposures with the highest Strehl ratios are selected. When these exposures are shifted and added together, field stars in the resulting images have Strehl ratios as high as 0.26 and full width at half maximum flux (FWHM) as small as 90 milliarcseconds. Within the selected exposures the isoplanatic patch is found to be up to 60 arcseconds in diameter at 810 nm wavelength. Images within globular clusters and of multiple stars from the Nordic Optical Telescope using reference stars as faint asI 16 are presented. A new generation of CCDs (Marconi L3Vision CCDs) were used in these observations, allowing extremely low noise high frame-rate imaging with both fine pixel sampling and a relatively wide field of view. The theoretical performance of these CCDs is compared with the experimental results obtained.
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 Lucky Exposures written by Robert Tubbs and published by VDM Publishing. This book was released on 2008-05-01 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph describes the "Lucky" imaging method developed at the University of Cambridge between 1999 and 2003. This technique allows the distorting effects of the Earth's atmosphere to be reduced, so that high resolution images of astronomical sources can be captured. The Lucky Exposures method is passive, relying on a high frame-rate camera in the image plane of a telescope to record the atmospheric speckle patterns. In the past the poor signal-to-noise performance of high frame-rate cameras has often limited passive high-resolution observations to relatively bright targets. Through a combination of novel processing techniques and new L3Vision camera technology, the Lucky Exposures method can now image much fainter targets. Details of these processing techniques and an assessment of the L3Vision performance are presented in this monograph. From good astronomical observatories, up to one quarter of the night sky is within range of a suitable reference star for this technique. The processing techniques described are applicable to data taken with a wide range of astronomical instruments, including observations using webcams on small- to medium-sized telescopes.
Download or read book Optical 3D Spectroscopy for Astronomy written by Roland Bacon and published by John Wiley & Sons. This book was released on 2017-06-19 with total page 307 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last 50 years, a variety of techniques have been developed to add a third dimension to regular imaging, with an extended spectrum associated to every imaging pixel. Dubbed 3D spectroscopy from its data format, it is now widely used in the astrophysical domain, but also inter alia for atmospheric sciences and remote sensing purposes. This is the first book to comprehensively tackle these new capabilities. It starts with the fundamentals of spectroscopic instruments, in particular their potentials and limits. It then reviews the various known 3D techniques, with particular emphasis on pinpointing their different `ecological? niches. Putative users are finally led through the whole observing process, from observation planning to the extensive ? and crucial - phase of data reduction. This book overall goal is to give the non-specialist enough hands-on knowledge to learn fast how to properly use and produce meaningful data when using such a 3D capability.
Download or read book Diffraction limited Imaging on the 200 inch Telescope written by Tadashi Nakajima and published by . This book was released on 1989 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Diffraction Limited Imaging with Very Large Telescopes written by Danielle M. Alloin and published by . This book was released on 1989 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Astronomical Image Reconstruction written by Simon P. Worden and published by . This book was released on 1975 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently proposed methods for reconstructing large telescope astronomical images free from atmospheric perturbation are reviewed and discussed. (Author).
Download or read book Diffraction Limited Imaging Using Aberrated Optics written by D. A. Fish and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Astronomical Optics written by Daniel J. Schroeder and published by Elsevier. This book was released on 2012-12-02 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by a recognized expert in the field, this clearly presented, well-illustrated book provides both advanced level students and professionals with an authoritative, thorough presentation of the characteristics, including advantages and limitations, of telescopes and spectrographic instruments used by astronomers of today. Written by a recognized expert in the field Provides both advanced level students and professionals with an authoritative, thorough presentation of the characteristics, including advantages and limitations, of telescopes and spectrographic instruments used by astronomers of today
Download or read book Astronomical Optics written by Daniel J. Schroeder and published by Elsevier. This book was released on 1999-09-27 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a unified treatment of the characteristics of telescopes of all types, both those whose performance is set by geometrical aberrations and the effect of the atmosphere, and those diffraction-limited telescopes designed for observations from above the atmosphere. The emphasis throughout is on basic principles, such as Fermat's principle, and their application to optical systems specifically designed to image distant celestial sources. The book also contains thorough discussions of the principles underlying all spectroscopic instrumentation, with special emphasis on grating instruments used with telescopes. An introduction to adaptive optics provides the needed background for further inquiry into this rapidly developing area. Geometrical aberration theory based on Fermat's principle Diffraction theory and transfer function approach to near-perfect telescopes Thorough discussion of 2-mirror telescopes, including misalignments Basic principles of spectrometry; grating and echelle instruments Schmidt and other catadioptric telescopes Principles of adaptive optics Over 220 figures and nearly 90 summary tables
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 Adaptive Optics written by Michael S. Tarov and published by Nova Publishers. This book was released on 2002 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive optics is a field which is coming into its own with new discoveries occurring almost daily both in astronomy and in applications of AO in applied fields. In an adaptive optics system, the output from a wavefront sensor is used to calculate corrections that actively remove distortions from an image. The applications of adaptive optics in vision science have received considerable impetus from the knowledge developed by astronomers about how to correct images using AO technology. It is expected that developments in adaptive optics will radically change the face of astronomy in the 21st century. These systems will largely overcome the main limitation of ground-based telescopes, namely the severe reduction in image quality caused by turbulence in the Earth's atmosphere. Intended for use at near infrared wavelengths, adaptive optics allow imaging and spectroscopy at the limit of resolution imposed by optical diffraction an advance in astronomer's ability to view the heavens unparalleled since the invention of the telescope. AO is now also entering clinical medicine in the field of ophthalmology and other related fields. This new book presents several hundred current abstracts in the field, each fully indexed, for ease of access and contains a CD ROM for further research.
Download or read book Investigations of High Resolution Imaging Through the Earth s Atmosphere Using Speckle Interferometry written by E. K. Hege and published by . This book was released on 1984 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: Speckle interferometry is a post-detection image processing technique for producing diffraction limited data using large astronomical telescopes in the presence of Earth's turbulent atmosphere which otherwise limits the imaging resolution. The Steward Observatory digital video speckle interferometry system consists of subsystems for a) video digitization of intensified, magnified, focal-plane images, b) Fourier transform (or autocorrelation) signal processing, and c) image analysis to produce the final interpreted results. Speckle interferometry has now been shown capable of yielding diffraction images for objects as faint as visual magnitude 16. Objectives of present developments are to improve a) the resolution (by using the Multiple Mirror Telescope with its 6. 9m optical aperture), b) the accuracy of the derived results (by implementing better photon detection and recording devices), and c) the efficiency and speed of the reduction algorithms which extract the information (by means of high- speed digital signal-processing hardware). The work includes a growing effect in speckle image reconstruction using a combination of amplitude processing, various phase retrieval methods, holographic methods, and shift-and-add methods. The techniques have been applied to observations of Earth-orbiting satellites, asteroids, Pluto/Charon, binary stars, bright supergiant stars, active galactic nuclei, and quasi-stellar objects (QSOs). Originator-supplied keywords: Speckle interferometry; Image reconstruction; Optical interferometry, Phased optical arrays, MMT, Diffraction limited imaging, Speckle imaging.
