Download or read book High Resolution Optical Imaging Through the Atmosphere written by Robert W. Noyes and published by . This book was released on 1989 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: This program has concentrated on three major areas: the application of high angular resolution image reconstruction techniques to the reconstruction of solar surface features; speckle imaging of a wide range of astronomical sources; and the implementation of adaptive optics for faint object imaging. In this project, we have made substantial modifications to a technique for reconstruction of high resolution images from single short exposure solar frames, blind iterative deconvolution (IDC). We have been testing these improvements using numerical simulation data. Analysis of speckle data of the supernova SN1987A has detected a new bright source, 0.9 arcseconds south of the SN, as well as substantial structure in the region surrounding the SN. We also have new results on several Young Stellar Objects and supergiants. In the area of adaptive optics, an AOA wavefront sensor has been set up and tested using an image intensifier which increases its sensitivity by three orders of magnitude. Faint object image active tilt correction has also been tested with some important enhancements, including new highly linear and sensitive CCD quad cells developed by Cal Tech and Tektronix, and an off-the-shelf high speed 2-D tilting mirror with greatly improved specifications. The effects of only partially correcting atmospheric turbulence have been theoretically analyzed and numerically simulated.
Download or read book Investigations of High Resolution Imaging Through the Earth s Atmosphere Using Speckle Interferometry written by E. Keith Hege and published by . This book was released on 1987 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Speckle Interferometry can now be used to produce images with spatial resolution of order 100x sharper than that normally permitted by the Earth's atmosphere. During this two year program of technique development we achieved high resolution imaging capability (wavelength dependent; 60 nrad at 410 nm) and approached that resolution in imaging a geosynchronous communications satellite utilizing the Multiple Mirror Telescope (MMT) and the Fienup method. We continued the pattern of parallel programs established in our previous AFGL work: E.D. Hege, P.A. Strittmatter and N.J. Woolf, Investigations of High Resolution Imaging Through the Earth's Atmosphere Using Speckle Interferometry, AFGL Report AFGL-TR-84-0116, 1984. Specific to this contract work, in our first year we completed a fully co-phased optical beam-combiner for implementation of the full 6.9m aperture imaging capability of the MMT. During our second year we met our final objective, by producing a 100 nrad resolution image of the geosynchronous Earth satellite FLTSATCOMl. We have proposed designs for systems to accomplish in real-time the data integrations necessary for Fienup and Knox-Thompson image reconstructions. Throughout the interval we continued work on algorithm development and seeing calibration. Our most notable achievement was applications of seeing calibration techniques and refinements of the shift-and-add method applied successfully in our scientific program of studies of red supergiants.
Download or read book Second Harmonic Generation Imaging written by Francesco S. Pavone and published by Taylor & Francis. This book was released on 2016-04-19 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: Second-harmonic generation (SHG) microscopy has shown great promise for imaging live cells and tissues, with applications in basic science, medical research, and tissue engineering. Second Harmonic Generation Imaging offers a complete guide to this optical modality, from basic principles, instrumentation, methods, and image analysis to biomedical a
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 In Vivo Optical Imaging of Brain Function written by Ron D. Frostig and published by CRC Press. This book was released on 2009-05-06 with total page 494 pages. Available in PDF, EPUB and Kindle. Book excerpt: These are exciting times for the field of optical imaging of brain function. Rapid developments in theory and technology continue to considerably advance understanding of brain function. Reflecting changes in the field during the past five years, the second edition of In Vivo Optical Imaging of Brain Function describes state-of-the-art techniques a
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.
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 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 Superresolution Imaging Through Atmospheric Turbulence written by David Roderick Gerwe and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The angular resolution of an imaging system is ultimately limited by diffraction effects related to the size of the image pupil once imperfections such as aberrations in the optical surfaces, grainy film, and noisy electronics have been eliminated. However, because of scatterings by turbulence, aerosols, and other inhomogeneities, the atmosphere diminishes the spatial coherence of propagating radiation and reduces the achievable resolution. Improving our ability to see through the atmosphere is of unmeasurable usefulness in astronomy, satellite imaging, remote detection, and all other areas in which high-resolution is desirable.
Download or read book Mimo Optical Communications and Imaging Through Turbulent Cloudy Atmosphere written by Zeinab Hajjarian Kashany and published by . This book was released on 2009 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the invention of Laser in 1960, Free Space Optics has been revolutionized in every aspect. The ever-increasing demand for high data rate communications, congestion of useful parts of the radio frequency (RF) band, and the costly installation of cable for last mile communications has spurred the use of Free Space Optical (FSO) communication as a novel broadband access technique. Another application of Free Space Optics, i.e. Optical imaging is preferred over RF counter parts due to its higher resolution, faster area search rate, and ease of interpretation by a human observer. All these benefits can be achieved due to smaller wavelength of optical waves. Free Space Optics; however, has its own challenges. In contrast to radio wavelengths, the optical wavelengths are of the same order of particle size in vapor; therefore, such particles interact with laser beams and scatter them. As a result of these multiple scattering, laser beam is broadened and the energy is redistributed in space and time. Furthermore, in an optical imaging system, back-scattered light impinges on the receiver and gives rise to a steady background noise, and hence limits the contrast. Moreover, refractive index variations, across the optical wave propagation path, cause amplitude and phase fluctuations in the received wave-front. While in optical communications system, amplitude and phase fluctuations give rise to fading, optical imaging systems experience severe resolution degradation due to PSF broadening. Multiple-Input Multiple-Output (MIMO) configuration is proved to be effective in fading RF channels. Moreover, multi-spot diffuse configuration, first introduced by Yun and Kavehrad [9], has a great potential to be exploited in optical imaging. In this dissertation, we propose MIMO imaging and communications systems and investigate their performance under various atmospheric conditions. Then using restoration techniques, we try to find a solution for performance degrading atmospheric phenomena.
Download or read book Optical Measurements for Scientists and Engineers written by Arthur McClelland and published by Cambridge University Press. This book was released on 2018-04-19 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt: An accessible, introductory text explaining how to select, set up and use optical spectroscopy and optical microscopy techniques.
Download or read book Optical Imaging and Aberrations written by Virendra N. Mahajan and published by SPIE-International Society for Optical Engineering. This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ten years have passed since the publication of the first edition of this classic text in April 2001. Considerable new material amounting to 100 pages has been added in this second edition. Each chapter now contains a Summary section at the end. The new material in Chapter 4 consists of a detailed comparison of Gaussian apodization with a corresponding beam, determination of the optimum value of the Gaussian radius relative to that of the pupil to yield maximum focal-point irradiance, detailed discussion of standard deviation, aberration balancing, and Strehl ratio for primary aberrations, derivation of the aberration-free and defocused OTF, discussion of an aberrated beam yielding higher axial irradiance in a certain defocused region than its aberration-free focal-point value, illustration that aberrated PSFs lose the advantage of Gaussian apodizaton in reducing the secondary maxima of a PSF, and a brief description of the characterization of the width of a multimode beam. In Chapter 5, the effect of random longitudinal defocus on a PSF is included. The coherence length of atmospheric turbulence is calculated for looking both up and down through the atmosphere. Also discussed are the angle of arrival of a light wave propagating through turbulence, and lucky imaging where better-quality short-exposure images are selected, aligned, and added to obtain a high-quality image.
Download or read book General Theory of Light Propagation and Imaging Through the Atmosphere written by T. Stewart McKechnie and published by Springer Nature. This book was released on 2022-10-06 with total page 694 pages. Available in PDF, EPUB and Kindle. Book excerpt: This 2nd edition lays out an updated version of the general theory of light propagation and imaging through Earth’s turbulent atmosphere initially developed in the late ‘70s and ‘80s, with additional applications in the areas of laser communications and high-energy laser beam propagation. New material includes a chapter providing a comprehensive mathematical tool set for precisely characterizing image formation with the anticipated Extremely Large Telescopes (ELTS), enabling a staggering range of star image shapes and sizes; existing chapters rewritten or modified so as to supplement the mathematics with clearer physical insight through written and graphical means; a history of the development of present-day understanding of light propagation and imaging through the atmosphere as represented by the general theory described. Beginning with the rudimentary, geometrical-optics based understanding of a century ago, it describes advances made in the 1960s, including the development of the ‘Kolmogorov theory,’ the deficiencies of which undermined its credibility, but not before it had done enormous damage, such as construction of a generation of underperforming ‘light bucket’ telescopes. The general theory requires no a priori turbulence assumptions. Instead, it provides means for calculating the turbulence properties directly from readily-measurable properties of star images.
Download or read book Optical Imaging and Aberrations written by Virendra N. Mahajan and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ten years have passed since the publication of the first edition of this classic text in April 2001. Considerable new material amounting to 100 pages has been added in this second edition. Each chapter now contains a Summary section at the end. The new material in Chapter 4 consists of a detailed comparison of Gaussian apodization with a corresponding beam, determination of the optimum value of the Gaussian radius relative to that of the pupil to yield maximum focal-point irradiance, detailed discussion of standard deviation, aberration balancing, and Strehl ratio for primary aberrations, derivation of the aberration-free and defocused OTF, discussion of an aberrated beam yielding higher axial irradiance in a certain defocused region than its aberration-free focal-point value, illustration that aberrated PSFs lose the advantage of Gaussian apodizaton in reducing the secondary maxima of a PSF, and a brief description of the characterization of the width of a multimode beam. In Chapter 5, the effect of random longitudinal defocus on a PSF is included. The coherence length of atmospheric turbulence is calculated for looking both up and down through the atmosphere. Also discussed are the angle of arrival of a light wave propagating through turbulence, and lucky imaging where better-quality short-exposure images are selected, aligned, and added to obtain a high-quality image.
Download or read book High Resolution 3 D Tomographic Imaging by Wavelength and Polarization Diversity written by N. H. Farhat and published by . This book was released on 1983 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Research in high resolution microwave imaging has to date concentrated broadly on the study and development of efficient and cost-effective data acquisition and image reconstruction methods for use in lambda and polarization diversity 3-D tomographic imaging. The techniques developed, combine angular, spectral, and polarization diversity measurements with a unique targetr derived reference technique to produce images of the scattering centers on complex-shaped bodies with unprecedented resolution and quality that exceed by far anything reported to this date. Analytical studies of information content, speckle suppression and resolution show however that image quality can further be enhanced and made to approach and even exceed the resolution of optical systems when the imaging or remote objects specially through the earth's atmosphere is desired.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 1460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book High Resolution Imaging written by Swapan K. Saha and published by CRC Press. This book was released on 2015-01-28 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interferometric observations need snapshots of very high time resolution of the order of (i) frame integration of about 100 Hz or (ii) photon-recording rates of several megahertz (MHz). Detectors play a key role in astronomical observations, and since the explanation of the photoelectric effect by Albert Einstein, the technology has evolved rather
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.
