Download or read book Laser Guide Star Adaptive Optics for Astronomy written by N. Ageorges and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive optics allows the theoretical limit of angular resolution to be achieved from a large telescope, despite the presence of turbulence. Thus an eight meter class telescope, such as one of the four in the Very Large Telescope operated by ESO in Chile, will in future be routinely capable of an angular resolution of almost 0.01 arcsec, compared tot he present resolution of about 0.5 arcsec for conventional imaging in good condition. All the world's major telescopes either have adaptive optics or are in the process of building AO systems. It turns out that a reasonable fraction of the sky can be observed using adaptive optics, with moderately good imaging quality, provided imaging in done in the near IR. To move out of the near IR, with its relatively poor angular resolution, astronomers need a laser guide star. There is a layer of Na atoms at approximately 90 km altitude that can be excited by a laser to produce such a source, or Rayleigh scattering can be employed lower in the atmosphere. But the production and use of laser guide stars is not trivial, and the key issues determining their successful implementation are discussed here, including the physics of the Na atom, the cone effect, tilt determination, sky coverage, and numerous potential astronomical applications.

Download or read book Laser Guide Star Adaptive Optics written by and published by . This book was released on 1993 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Feasibility demonstrations using one to two meter telescopes have confirmed the utility of laser beacons as wavefront references for adaptive optics systems. Laser beacon architectures suitable for the new generation of eight and ten meter telescopes are presently under study. This paper reviews the concept of laser guide star adaptive optics and the progress that has been made by groups around the world implementing such systems. A description of the laser guide star program at LLNL and some experimental results is also presented.

Download or read book Simulation and Analysis of Laser Guide Star Adaptive Optics Systems for the Eight to Ten Meter Class Telescopes written by and published by . This book was released on 1994 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper discusses the design and analysis of laser-guided adaptive optic systems for the large, 8--10 meter class telescopes. We describe a technique for calculating the expected modulation transfer function and the point spread function for a closed loop adaptive optics system, parameterized by the degree of correction and the seeing conditions. The results agree closely with simulations and experimental data, and validate well known scaling law models even at low order correction. Scaling law.model analysis of a proposed adaptive optics system at the Keck telescope leads to the conclusion that a single laser guide star beacon will be adequate for diffraction limited imaging at wavelengths between 1 and 3 am with reasonable coverage of the sky. Cone anisoplanatism will dominate wavefront correction error at the visible wavelengths unless multiple laser guide stars are used.

Download or read book An Experimental Rayleigh Laser Guide Star Ground Layer Adaptive Optics System for the William Herschel Telescope written by and published by . This book was released on 2005 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Sodium Laser Guide Star Experiment for Adaptive Optics and the Development of a High Bandwidth Tracking System for the University of Chicago Adaptive Optics System written by Fang Shi and published by . This book was released on 1999 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental Analysis of Perspective Elongation Effects Using a Laser Guide Star in an Adaptive Optics System POSTPRINT written by and published by . This book was released on 2009 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of a laser guidestar (LGS) for the purpose of a beacon in an adaptive-optics (AO) system is prone to perspective elongation effects on the spots of a Shack-Hartmann wavefront sensor. The elongated spots can vary in size over the subapertures and affect the gradient sensitivity of the sensor. The Air Force Research Laboratory (AFRL) has developed a LGS model that outputs gradient gains which represent the effects of an extended beacon on the spots for a Shack-Hartmann wavefront sensor. This paper investigates the application of these gains in an experimental setup in order to both analyze the effects of the variation in those gains due to spot size elongation and to measure the impact on the performance of an AO system.

Download or read book Design and Early Results of the Sodium layer Laser Guide Star Adaptive Optics Experiment at the Lawrence Livermore National Laboratory written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive optic systems promise to give diffraction limited performance to ground based telescopes operating at visible and near infrared wavelengths. However, because of the short spatial scale of atmospheric turbulence, the corrected field of view is limited to only a few arc seconds in the visible, to perhaps 10 arc seconds at L band (3.5 [mu]). A bright point source must be in this field of view as a wavefront reference, but the number density of natural stars is too small for full sky coverage at imaging wavelengths less than 3[mu]. A sufficiently bright point source can be artificially generated by a laser however, and investigations into the use of laser beacons has been proceeding for some time now. Our experiments at Livermore have concentrated on the formation of guide stars in the sodium mesospheric layer at 90 km altitude. We have also designed and built adaptive optics systems that use both artificial and natural guide stars. Experimental results to date have shown great promise for the practicality of this technique in astronomy.

Download or read book Performance of Laser Guide Star Adaptive Optics at Lick Observatory written by and published by . This book was released on 1995 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: A sodium-layer laser guide star adaptive optics system has been developed at Lawrence Livermore National Laboratory (LLNL) for use on the 3-meter Shane telescope at Lick Observatory. The system is based on a 127-actuator continuous-surface deformable mirror, a Hartmann wavefront sensor equipped with a fast-framing low-noise CCD camera, and a pulsed solid-state-pumped dye laser tuned to the atomic sodium resonance line at 589 nm. The adaptive optics system has been tested on the Shane telescope using natural reference stars yielding up to a factor of 12 increase in image peak intensity and a factor of 6.5 reduction in image full width at half maximum (FWHM). The results are consistent with theoretical expectations. The laser guide star system has been installed and operated on the Shane telescope yielding a beam with 22 W average power at 589 nm. Based on experimental data, this laser should generate an 8th magnitude guide star at this site, and the integrated laser guide star adaptive optics system should produce images with Strehl ratios of 0.4 at 2.2 [mu]m in median seeing and 0.7 at 2.2 [mu]m in good seeing.

Download or read book Improved Performance of the Laser Guide Star Adaptive Optics System at Lick Observatory written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of experiments with the laser guide star adaptive optics system on the 3-meter Shane telescope at Lick Observatory have demonstrated a factor of 4 performance improvement over previous results. Stellar images recorded at a wavelength of 2 [mu]m were corrected to over 40% of the theoretical diffraction-limited peak intensity. For the previous two years, this sodium-layer laser guide star system has corrected stellar images at this wavelength to ≈10% of the theoretical peak intensity limit. After a campaign to improve the beam quality of the laser system, and to improve calibration accuracy and stability of the adaptive optics system using new techniques for phase retrieval and phase-shifting diffraction interferometry, the system performance has been substantially increased. The next step will be to use the Lick system for astronomical science observations, and to demonstrate this level of performance with the new system being installed on the 10-meter Keck II telescope.

Download or read book Laser Guide Stars and Adaptive Optics for Astronomy written by and published by . This book was released on 1992 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: Five papers are included: feasibility experiment for sodium-alyer laser guide stars at LLNL; system design for a high power sodium beacon laser; sodium guide star adaptive optics system for astronomical imaging in the visible and near-infrared; high frame-rate, large field wavefront sensor; and resolution limits for ground-based astronomical imaging. Figs, tabs, refs.

Download or read book Astronomical Adaptive Optics Using Multiple Laser Guide Stars written by Christoph James Baranec and published by . This book was released on with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past several years, experiments in adaptive optics involving multiple natural and laser guide stars have been carried out at the 1.55 m Kuiper telescope and the 6.5 m MMT telescope. The astronomical imaging improvement anticipated from both ground-layer and tomographic adaptive optics has been calculated. Ground-layer adaptive optics will reduce the effects of atmospheric seeing, increasing the resolution and sensitivity of astronomical observations over wide fields. Tomographic adaptive optics will provide diffraction-limited imaging along a single line of sight, increasing the amount of sky coverage available to adaptive optics correction. A new facility class wavefront sensor has been deployed at the MMT which will support closed-loop adaptive optics correction using a constellation of five Rayleigh laser guide stars and the deformable F/15 secondary mirror. The adaptive optics control loop was closed for the first time around the focus signal from all five laser signals in July of 2007, demonstrating that the system is working properly. It is anticipated that the full high-order ground-layer adaptive optics loop, controlled by the laser signals in conjunction with a tip/tilt natural guide star, will be closed in September 2007, with the imaging performance delivered by the system optimized and evaluated. The work here is intended to be both its own productive scientific endeavor for the MMT, but also as a proof of concept for the advanced adaptive optics systems designed to support observing at the Large Binocular Telescope and future extremely large telescopes such as the Giant Magellan Telescope.

Download or read book Laser Guide Star Adaptive Optics Workshop written by and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Guide Star Lasers For Adaptive Optics PHD written by William Thomas Roberts and published by . This book was released on with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser Guide Star Adaptive Optics Workshop written by Robert Q. Fugate and published by . This book was released on 1992* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sodium Laser Guide Star Technique Spectroscopy and Imaging with Adaptive Optics PHD written by Ge Jian and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Principles of Adaptive Optics written by Robert K. Tyson and published by CRC Press. This book was released on 2022-02-28 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: Principles of Adaptive Optics describes the foundations, principles, and applications of adaptive optics (AO) and its enabling technologies. This leading textbook addresses the fundamentals of AO at the core of astronomy, high-energy lasers, biomedical imaging, and optical communications. Key Features: Numerous examples to explain and support the underlying principles Hundreds of new references to support the topics that are addressed End-of-chapter questions and exercises A complete system design example threaded through each chapter as new material is introduced

Download or read book Laser Guide Star Only Adaptive Optics written by Andrew Paul Reeves and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: