Diffraction-limited Imaging with Large and Moderate Telescopes

Diffraction-limited Imaging with Large and Moderate Telescopes PDF

Author: Swapan K. Saha

Publisher: World Scientific

Published: 2007

Total Pages: 633

ISBN-13: 9812707778

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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.

Diffraction-Limited Imaging with Large and Moderate Telescopes

Diffraction-Limited Imaging with Large and Moderate Telescopes PDF

Author: Swapan K. Saha

Publisher: World Scientific

Published: 2007

Total Pages: 633

ISBN-13: 981270888X

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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.

Diffraction-Limited Imaging with Very Large Telescopes

Diffraction-Limited Imaging with Very Large Telescopes PDF

Author: D.M. Alloin

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 444

ISBN-13: 9400923406

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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.

Lucky Exposures

Lucky Exposures PDF

Author: Robert Tubbs

Publisher: VDM Publishing

Published: 2008-05-01

Total Pages: 152

ISBN-13: 9783836497695

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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.

Aperture Synthesis

Aperture Synthesis PDF

Author: Swapan Kumar Saha

Publisher: Springer Science & Business Media

Published: 2010-10-17

Total Pages: 482

ISBN-13: 1441957103

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This book deals with the fundamentals of stellar interferometry with emphasis on aperture synthesis using sparse array of telescopes particularly at optical/IR wavelengths, the origin, properties, and optical effects of turbulence in the Earth's atmosphere, techniques developed to overcome image degradation. Studded with more than one hundred and fifty illustrations and tens of footnotes, it addresses the basic tricks of trade, current trend, motivation, methods, and path to future promise of true interferometry both from the ground and space. Also discussed are the technical challenge involved, such as beam transportation and recombination, detecting fringes using modern sensors, and image synthesis. Astronomical science that benefits from aperture synthesis imaging are highlighted as well.

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