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Sample records for adaptive optics survey

  1. The Robo-AO KOI Survey: laser adaptive optics imaging of every Kepler exoplanet candidate

    CERN Document Server

    Ziegler, Carl; Baranec, Christoph; Morton, Tim; Riddle, Reed; Atkinson, Dani; Nofi, Larissa

    2016-01-01

    The Robo-AO Kepler Planetary Candidate Survey is observing every Kepler planet candidate host star (KOI) with laser adaptive optics imaging to hunt for blended nearby stars which may be physically associated companions. With the unparalleled efficiency provided by the first fully robotic adaptive optics system, we perform the critical search for nearby stars (0.15" to 4.0" separation with contrasts up to 6 magnitudes) that dilute the observed planetary transit signal, contributing to inaccurate planetary characteristics or astrophysical false positives. We present 3313 high resolution observations of Kepler planetary hosts from 2012-2015, discovering 479 nearby stars. We measure an overall nearby star probability rate of 14.5\\pm0.8%. With this large data set, we are uniquely able to explore broad correlations between multiple star systems and the properties of the planets which they host, providing insight into the formation and evolution of planetary systems in our galaxy. Several KOIs of particular interest...

  2. The Robo-AO KOI Survey: Laser Adaptive Optics Imaging of Every Kepler Exoplanet Candidate

    Science.gov (United States)

    Ziegler, Carl; Law, Nicholas M.; Baranec, Christoph; Morton, Tim; Riddle, Reed L.

    2016-01-01

    The Robo-AO Kepler Planetary Candidate Survey is observing every Kepler planet candidate host star (KOI) with laser adaptive optics imaging to hunt for blended nearby stars which may be physically associated companions. With the unparalleled efficiency provided by the first fully robotic adaptive optics system, we perform the critical search for nearby stars (0.15" to 4.0" separation with contrasts up to 6 magnitudes) that pollute the observed planetary transit signal, contributing to inaccurate planetary characteristics or astrophysical false positives. We present approximately 3300 high resolution observations of Kepler planetary hosts from 2012-2015, with ~500 observed nearby stars. We measure an overall nearby star probability rate of 16.2±0.8%. With this large dataset, we are uniquely able to explore broad correlations between multiple star systems and the properties of the planets which they host. We then use these clues for insight into the formation and evolution of these exotic systems. Several KOIs of particular interest will be discussed, including possible quadruple star systems hosting planets and updated properties for possible rocky planets orbiting in the habitable zone.

  3. The Robo-AO KOI survey: laser adaptive optics imaging of every Kepler exoplanet candidate

    Science.gov (United States)

    Ziegler, Carl; Law, Nicholas M.; Baranec, Christoph; Morton, Tim; Riddle, Reed; Atkinson, Dani; Nofi, Larissa

    2016-07-01

    The Robo-AO Kepler Planetary Candidate Survey is observing every Kepler planet candidate host star (KOI) with laser adaptive optics imaging to hunt for blended nearby stars which may be physically associated companions. With the unparalleled efficiency provided by the first fully robotic adaptive optics system, we perform the critical search for nearby stars (0.15" to 4.0" separation with contrasts up to 6 magnitudes) that dilute the observed planetary transit signal, contributing to inaccurate planetary characteristics or astrophysical false positives. We present 3313 high resolution observations of Kepler planetary hosts from 2012-2015, discovering 479 nearby stars. We measure an overall nearby star probability rate of 14.5+/-0.8%. With this large data set, we are uniquely able to explore broad correlations between multiple star systems and the properties of the planets which they host, providing insight into the formation and evolution of planetary systems in our galaxy. Several KOIs of particular interest will be discussed, including possible quadruple star systems hosting planets and updated properties for possible rocky planets orbiting with in their star's habitable zone.

  4. Simulation of a ground-layer adaptive optics system for the Kunlun Dark Universe Survey Telescope

    Institute of Scientific and Technical Information of China (English)

    Peng Jia; Sijiong Zhang

    2013-01-01

    Ground Layer Adaptive Optics (GLAO) is a recently developed technique extensively applied to ground-based telescopes,which mainly compensates for the wavefront errors induced by ground-layer turbulence to get an appropriate point spread function in a wide field of view.The compensation results mainly depend on the turbulence distribution.The atmospheric turbulence at Dome A in the Antarctic is mainly distributed below 15 meters,which is an ideal site for applications of GLAO.The GLAO system has been simulated for the Kunlun Dark Universe Survey Telescope,which will be set up at Dome A,and uses a rotating mirror to generate several laser guide stars and a wavefront sensor with a wide field of view to sequentially measure the wavefronts from different laser guide stars.The system is simulated on a computer and parameters of the system are given,which provide detailed information about the design of a practical GLAO system.

  5. Principles of adaptive optics

    CERN Document Server

    Tyson, Robert

    2010-01-01

    History and BackgroundIntroductionHistoryPhysical OpticsTerms in Adaptive OpticsSources of AberrationsAtmospheric TurbulenceThermal BloomingNonatmospheric SourcesAdaptive Optics CompensationPhase ConjugationLimitations of Phase ConjugationArtificial Guide StarsLasers for Guide StarsCombining the LimitationsLinear AnalysisPartial Phase ConjugationAdaptive Optics SystemsAdaptive Optics Imaging SystemsBeam Propagation Syst

  6. [Adaptive optics for ophthalmology].

    Science.gov (United States)

    Saleh, M

    2016-04-01

    Adaptive optics is a technology enhancing the visual performance of an optical system by correcting its optical aberrations. Adaptive optics have already enabled several breakthroughs in the field of visual sciences, such as improvement of visual acuity in normal and diseased eyes beyond physiologic limits, and the correction of presbyopia. Adaptive optics technology also provides high-resolution, in vivo imaging of the retina that may eventually help to detect the onset of retinal conditions at an early stage and provide better assessment of treatment efficacy.

  7. Subaru Telescope adaptive optics observations of gravitationally lensed quasars in the Sloan Digital Sky Survey

    CERN Document Server

    Rusu, Cristian E; Minowa, Yosuke; Iye, Masanori; Inada, Naohisa; Oya, Shin; Kayo, Issha; Hayano, Yutaka; Hattori, Masayuki; Saito, Yoshihiko; Ito, Meguru; Pyo, Tae-Soo; Terada, Hiroshi; Takami, Hideki; Watanabe, Makoto

    2015-01-01

    We present the results of an imaging observation campaign conducted with the Subaru Telescope adaptive optics system (IRCS+AO188) on 26 gravitationally lensed quasars (24 doubles, 1 quad, and 1 possible triple) from the SDSS Quasar Lens Search. We develop a novel modelling technique that fits analytical and hybrid point spread functions (PSFs), while simultaneously measuring the relative astrometry, photometry, as well as the lens galaxy morphology. We account for systematics by simulating the observed systems using separately observed PSF stars. The measured relative astrometry is comparable with that typically achieved with the Hubble Space Telescope, even after marginalizing over the PSF uncertainty. We model for the first time the quasar host galaxies in 5 systems, without a-priory knowledge of the PSF, and show that their luminosities follow the known correlation with the mass of the supermassive black hole. For each system, we obtain mass models far more accurate than those previously published from low...

  8. Subaru Telescope adaptive optics observations of gravitationally lensed quasars in the Sloan Digital Sky Survey

    Science.gov (United States)

    Rusu, Cristian E.; Oguri, Masamune; Minowa, Yosuke; Iye, Masanori; Inada, Naohisa; Oya, Shin; Kayo, Issha; Hayano, Yutaka; Hattori, Masayuki; Saito, Yoshihiko; Ito, Meguru; Pyo, Tae-Soo; Terada, Hiroshi; Takami, Hideki; Watanabe, Makoto

    2016-05-01

    We present the results of an imaging observation campaign conducted with the Subaru Telescope adaptive optics system (IRCS+AO188) on 28 gravitationally lensed quasars and candidates (23 doubles, 1 quad, 1 possible triple, and 3 candidates) from the SDSS Quasar Lens Search. We develop a novel modelling technique that fits analytical and hybrid point spread functions (PSFs), while simultaneously measuring the relative astrometry, photometry, as well as the lens galaxy morphology. We account for systematics by simulating the observed systems using separately observed PSF stars. The measured relative astrometry is comparable with that typically achieved with the Hubble Space Telescope, even after marginalizing over the PSF uncertainty. We model for the first time the quasar host galaxies in five systems, without a priori knowledge of the PSF, and show that their luminosities follow the known correlation with the mass of the supermassive black hole. For each system, we obtain mass models far more accurate than those previously published from low-resolution data, and we show that in our sample of lensing galaxies the observed light profile is more elliptical than the mass, for ellipticity ≳0.25. We also identify eight doubles for which the sources of external and internal shear are more reliably separated, and should therefore be prioritized in monitoring campaigns aimed at measuring time delays in order to infer the Hubble constant.

  9. The Palomar/Keck Adaptive Optics Survey of Young Solar Analogs: Evidence for a Universal Companion Mass Function

    CERN Document Server

    Metchev, Stanimir

    2008-01-01

    We present results from an adaptive optics survey for substellar and stellar companions to Sun-like stars. The survey targeted 266 F5-K5 stars in the 3Myr to 3Gyr age range with distances of 10-190pc. Results from the survey include the discovery of two brown dwarf companions (HD49197B and HD203030B), 24 new stellar binaries, and a triple system. We infer that the frequency of 0.012-0.072Msun brown dwarfs in 28-1590AU orbits around young solar analogs is 3.2% (+3.1%,-2.7%; 2sigma limits). The result demonstrates that the deficiency of substellar companions at wide orbital separations from Sun-like stars is less pronounced than in the radial velocity "brown dwarf desert." We infer that the mass distribution of companions in 28-1590AU orbits around solar-mass stars follows a continuous dN/dM_2 ~ M_2^(-0.4) relation over the 0.01-1.0Msun secondary mass range, and that it differs significantly from the mass function of isolated objects. Based on this conclusion and on similar results from other direct imaging and...

  10. Robo-AO Kepler Planetary Candidate Survey II: Adaptive Optics Imaging of 969 Kepler Exoplanet Candidate Host Stars

    CERN Document Server

    Baranec, Christoph; Law, Nicholas M; Morton, Tim; Riddle, Reed; Atkinson, Dani; Schonhut, Jessica; Crepp, Justin

    2016-01-01

    We initiated the Robo-AO Kepler Planetary Candidate Survey in 2012 to observe each Kepler exoplanet candidate host star with high-angular-resolution visible-light laser-adaptive-optics imaging. Our goal is to find nearby stars lying in Kepler's photometric apertures that are responsible for the relatively high probability of false-positive exoplanet detections and that cause underestimates of the size of transit radii. Our comprehensive survey will also shed light on the effects of stellar multiplicity on exoplanet properties and will identify rare exoplanetary architectures. In this second part of our ongoing survey, we observed an additional 969 Kepler planet candidate hosts and we report blended stellar companions up to $\\Delta m \\approx 6$ that contribute to Kepler's measured light curves. We found 203 companions within $\\sim$4" of 181 of the Kepler stars, of which 141 are new discoveries. We measure the nearby-star probability for this sample of Kepler planet candidate host stars to be 10.6% $\\pm$ 1.1% a...

  11. Solar Adaptive Optics

    Directory of Open Access Journals (Sweden)

    Thomas R. Rimmele

    2011-06-01

    Full Text Available Adaptive optics (AO has become an indispensable tool at ground-based solar telescopes. AO enables the ground-based observer to overcome the adverse effects of atmospheric seeing and obtain diffraction limited observations. Over the last decade adaptive optics systems have been deployed at major ground-based solar telescopes and revitalized ground-based solar astronomy. The relatively small aperture of solar telescopes and the bright source make solar AO possible for visible wavelengths where the majority of solar observations are still performed. Solar AO systems enable diffraction limited observations of the Sun for a significant fraction of the available observing time at ground-based solar telescopes, which often have a larger aperture than equivalent space based observatories, such as HINODE. New ground breaking scientific results have been achieved with solar adaptive optics and this trend continues. New large aperture telescopes are currently being deployed or are under construction. With the aid of solar AO these telescopes will obtain observations of the highly structured and dynamic solar atmosphere with unprecedented resolution. This paper reviews solar adaptive optics techniques and summarizes the recent progress in the field of solar adaptive optics. An outlook to future solar AO developments, including a discussion of Multi-Conjugate AO (MCAO and Ground-Layer AO (GLAO will be given.

  12. Solar tomography adaptive optics.

    Science.gov (United States)

    Ren, Deqing; Zhu, Yongtian; Zhang, Xi; Dou, Jiangpei; Zhao, Gang

    2014-03-10

    Conventional solar adaptive optics uses one deformable mirror (DM) and one guide star for wave-front sensing, which seriously limits high-resolution imaging over a large field of view (FOV). Recent progress toward multiconjugate adaptive optics indicates that atmosphere turbulence induced wave-front distortion at different altitudes can be reconstructed by using multiple guide stars. To maximize the performance over a large FOV, we propose a solar tomography adaptive optics (TAO) system that uses tomographic wave-front information and uses one DM. We show that by fully taking advantage of the knowledge of three-dimensional wave-front distribution, a classical solar adaptive optics with one DM can provide an extra performance gain for high-resolution imaging over a large FOV in the near infrared. The TAO will allow existing one-deformable-mirror solar adaptive optics to deliver better performance over a large FOV for high-resolution magnetic field investigation, where solar activities occur in a two-dimensional field up to 60'', and where the near infrared is superior to the visible in terms of magnetic field sensitivity.

  13. Robo-AO Kepler Planetary Candidate Survey. II. Adaptive Optics Imaging of 969 Kepler Exoplanet Candidate Host Stars

    Science.gov (United States)

    Baranec, Christoph; Ziegler, Carl; Law, Nicholas M.; Morton, Tim; Riddle, Reed; Atkinson, Dani; Schonhut, Jessica; Crepp, Justin

    2016-07-01

    We initiated the Robo-AO Kepler Planetary Candidate Survey in 2012 to observe each Kepler exoplanet candidate host star with high angular resolution, visible light, laser adaptive optics (AOs) imaging. Our goal is to find nearby stars lying in Kepler's photometric apertures that are responsible for the relatively high probability of false-positive exoplanet detections and that cause underestimates of the size of transit radii. Our comprehensive survey will also shed light on the effects of stellar multiplicity on exoplanet properties and will identify rare exoplanetary architectures. In this second part of our ongoing survey, we observed an additional 969 Kepler planet candidate hosts and we report blended stellar companions up to {{Δ }}m≈ 6 that contribute to Kepler's measured light curves. We found 203 companions within ˜4″ of 181 of the Kepler stars, of which 141 are new discoveries. We measure the nearby star probability for this sample of Kepler planet candidate host stars to be 10.6% ± 1.1% at angular separations up to 2.″5, significantly higher than the 7.4% ± 1.0% probability discovered in our initial sample of 715 stars; we find the probability increases to 17.6% ± 1.5% out to a separation of 4.″0. The median position of Kepler Objects of Interest (KOIs) observed in this survey are 1.°1 closer to the galactic plane, which may account for some of the nearby star probability enhancement. We additionally detail 50 Keck AO images of Robo-AO observed KOIs in order to confirm 37 companions detected at a <5σ significance level and to obtain additional infrared photometry on higher significance detected companions.

  14. Robo-AO Kepler Planetary Candidate Survey. III. Adaptive Optics Imaging of 1629 Kepler Exoplanet Candidate Host Stars

    Science.gov (United States)

    Ziegler, Carl; Law, Nicholas M.; Morton, Tim; Baranec, Christoph; Riddle, Reed; Atkinson, Dani; Baker, Anna; Roberts, Sarah; Ciardi, David R.

    2017-02-01

    The Robo-AO Kepler Planetary Candidate Survey is observing every Kepler planet candidate host star with laser adaptive optics imaging to search for blended nearby stars, which may be physically associated companions and/or responsible for transit false positives. In this paper, we present the results of our search for stars nearby 1629 Kepler planet candidate hosts. With survey sensitivity to objects as close as ∼0.″15, and magnitude differences Δm ≤slant 6, we find 223 stars in the vicinity of 206 target KOIs; 209 of these nearby stars have not been previously imaged in high resolution. We measure an overall nearby-star probability for Kepler planet candidates of 12.6 % +/- 0.9 % at separations between 0.″15 and 4.″0. Particularly interesting KOI systems are discussed, including 26 stars with detected companions that host rocky, habitable zone candidates and five new candidate planet-hosting quadruple star systems. We explore the broad correlations between planetary systems and stellar binarity, using the combined data set of Baranec et al. and this paper. Our previous 2σ result of a low detected nearby star fraction of KOIs hosting close-in giant planets is less apparent in this larger data set. We also find a significant correlation between detected nearby star fraction and KOI number, suggesting possible variation between early and late Kepler data releases.

  15. Robo-AO Kepler Planetary Candidate Survey III: Adaptive Optics Imaging of 1629 Kepler Exoplanet Candidate Host Stars

    CERN Document Server

    Ziegler, Carl; Morton, Tim; Baranec, Christoph; Riddle, Reed; Atkinson, Dani; Baker, Anna; Roberts, Sarah; Ciardi, David R

    2016-01-01

    The Robo-AO \\textit{Kepler} Planetary Candidate Survey is observing every \\textit{Kepler} planet candidate host star with laser adaptive optics imaging to search for blended nearby stars, which may be physically associated companions and/or responsible for transit false positives. We present in this paper the results of our search for stars nearby 1629 \\textit{Kepler} planet candidate hosts. With survey sensitivity to objects as close as $\\sim$0.15" and magnitude differences $\\Delta$m$\\le$6, we find 223 stars in the vicinity of 206 target KOIs; 209 of these nearby stars have not previously been imaged in high resolution. We measure an overall nearby-star probability for \\textit{Kepler} planet candidates of 12.6\\%$\\pm$0.9\\% out to a separation of 4.0". Particularly interesting KOI systems are discussed, including 23 stars with detected companions which host rocky, habitable zone candidates, and five new candidate planet-hosting quadruple star systems. We explore the broad correlations between planetary systems...

  16. Holographic Adaptive Optics

    Science.gov (United States)

    Andersen, G.

    For the last two decades adaptive optics has been used as a technique for correcting imaging applications and directed energy/laser targeting and laser communications systems affected by atmospheric turbulence. Typically these systems are bulky and limited to system with the potential to operate at speeds of MHz. The system utilizes a hologram to perform an all-optical wavefront analysis that removes the need for any computer. Finally, the sensing is made on a modal basis so it is largely insensitive to scintillation and obscuration. We have constructed a prototype device and will present experimental results from our research. The holographic adaptive optics system begins with the creation of a multiplexed hologram. This hologram is created by recording the maximum and minimum response functions of every actuator in the deformable mirror against a unique focused reference beam. When a wavefront of some arbitrary phase is incident on the processed hologram, a number of focal spots are created -- one pair for each actuator in the DM. The absolute phase error at each particular actuator location is simply related to the ratio of the intensity of each pair of spots. In this way we can use an array of photodetectors to give a direct readout of phase error without the need for any calculations. The advantages of holographic adaptive optics are many. To begin with, the measurement of phase error is made all optically, so the wavefront sensor directly controls the actuators in the DM without any computers. Using fast, photon counting photodetectors allows for closed loop correction limited only by the speed of the deformable mirror which in the case of MEMS devices can be 100 kHz or more. All this can be achieved in an extremely compact and lightweight package making it perfectly suited to applications such as UAV surveillance imagery and free space optical communications systems. Lastly, since the correction is made on a modal basis instead of zonal, it is virtually

  17. Advanced Adaptive Optics Technology Development

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, S

    2001-09-18

    The NSF Center for Adaptive Optics (CfAO) is supporting research on advanced adaptive optics technologies. CfAO research activities include development and characterization of micro-electro-mechanical systems (MEMS) deformable mirror (DM) technology, as well as development and characterization of high-resolution adaptive optics systems using liquid crystal (LC) spatial light modulator (SLM) technology. This paper presents an overview of the CfAO advanced adaptive optics technology development activities including current status and future plans.

  18. Adaptive Optical Scanning Holography

    Science.gov (United States)

    Tsang, P. W. M.; Poon, Ting-Chung; Liu, J.-P.

    2016-01-01

    Optical Scanning Holography (OSH) is a powerful technique that employs a single-pixel sensor and a row-by-row scanning mechanism to capture the hologram of a wide-view, three-dimensional object. However, the time required to acquire a hologram with OSH is rather lengthy. In this paper, we propose an enhanced framework, which is referred to as Adaptive OSH (AOSH), to shorten the holographic recording process. We have demonstrated that the AOSH method is capable of decreasing the acquisition time by up to an order of magnitude, while preserving the content of the hologram favorably. PMID:26916866

  19. Lighter side of adaptive optics

    CERN Document Server

    Tyson, Robert K

    2009-01-01

    Adaptive optics has been under development for well over 40 years. It is an indisputable necessity for all major ground-based astronomical telescopes and is the foundation for laser and wavefront sensor design. Lighter Side of Adaptive Optics is a nontechnical explanation of optics, the atmosphere, and the technology for ""untwinkling"" the stars. While interweaving a fictional romantic relationship as an analogy to adaptive optics, and inserting satire, humor, and philosophical rants, Tyson makes a difficult scientific topic understandable. The ""why"" and ""how"" of adaptive optics has never

  20. ESO adaptive optics facility

    Science.gov (United States)

    Arsenault, R.; Madec, P.-Y.; Hubin, N.; Paufique, J.; Stroebele, S.; Soenke, C.; Donaldson, R.; Fedrigo, E.; Oberti, S.; Tordo, S.; Downing, M.; Kiekebusch, M.; Conzelmann, R.; Duchateau, M.; Jost, A.; Hackenberg, W.; Bonaccini Calia, D.; Delabre, B.; Stuik, R.; Biasi, R.; Gallieni, D.; Lazzarini, P.; Lelouarn, M.; Glindeman, A.

    2008-07-01

    ESO has initiated in June 2004 a concept of Adaptive Optics Facility. One unit 8m telescope of the VLT is upgraded with a 1.1 m convex Deformable Secondary Mirror and an optimized instrument park. The AO modules GALACSI and GRAAL will provide GLAO and LTAO corrections forHawk-I and MUSE. A natural guide star mode is provided for commissioning and maintenance at the telescope. The facility is completed by a Laser Guide Star Facility launching 4 LGS from the telescope centerpiece used for the GLAO and LTAO wavefront sensing. A sophisticated test bench called ASSIST is being designed to allow an extensive testing and characterization phase of the DSM and its AO modules in Europe. Most sub-projects have entered the final design phase and the DSM has entered Manufacturing phase. First light is planned in the course of 2012 and the commissioning phases should be completed by 2013.

  1. The VLT Adaptive Optics Facility Project: Adaptive Optics Modules

    Science.gov (United States)

    Arsenault, Robin; Hubin, Norbert; Stroebele, Stefan; Fedrigo, Enrico; Oberti, Sylvain; Kissler-Patig, Markus; Bacon, Roland; McDermid, Richard; Bonaccini-Calia, Domenico; Biasi, Roberto; Gallieni, Daniele; Riccardi, Armando; Donaldson, Rob; Lelouarn, Miska; Hackenberg, Wolfgang; Conzelman, Ralf; Delabre, Bernard; Stuik, Remko; Paufique, Jerome; Kasper, Markus; Vernet, Elise; Downing, Mark; Esposito, Simone; Duchateau, Michel; Franx, Marijn; Myers, Richard; Goodsell, Steven

    2006-03-01

    The Adaptive Optics Facility is a project to convert UT4 into a specialised Adaptive Telescope with the help of a Deformable Secondary Mirror (see previous article). The two instruments that have been identified for the two Nasmyth foci are: Hawk-I with its AO module GRAAL allowing a Ground Layer Adaptive Optics correction (GLAO) and MUSE with GALACSI for GLAO correction and Laser Tomography Adaptive Optics correction. This article describes the AO modules GRAAL and GALACSI and their Real-Time Computers based on SPARTA.

  2. Field guide to adaptive optics

    CERN Document Server

    Tyson, Robert

    2012-01-01

    This SPIE Field Guide provides a summary of the methods for determining the requirements of an adaptive optics system, the performance of the system, and the requirements for the components of the system. This second edition has a greatly expanded presentation of adaptive optics control system design and operation. Discussions of control models are accompanied by various recommendations for implementing the algorithms in hardware.

  3. Wavefront coding with adaptive optics

    Science.gov (United States)

    Agbana, Temitope E.; Soloviev, Oleg; Bezzubik, Vitalii; Patlan, Vsevolod; Verhaegen, Michel; Vdovin, Gleb

    2015-03-01

    We have implemented an extended depth of field optical system by wavefront coding with a micromachined membrane deformable mirror. This approach provides a versatile extension to standard wavefront coding based on fixed phase mask. First experimental results validate the feasibility of the use of adaptive optics for variable depth wavefront coding in imaging optical systems.

  4. Adaptive optical zoom sensor.

    Energy Technology Data Exchange (ETDEWEB)

    Sweatt, William C.; Bagwell, Brett E.; Wick, David Victor

    2005-11-01

    In order to optically vary the magnification of an imaging system, continuous mechanical zoom lenses require multiple optical elements and use fine mechanical motion to precisely adjust the separations between individual or groups of lenses. By incorporating active elements into the optical design, we have designed and demonstrated imaging systems that are capable of variable optical magnification with no macroscopic moving parts. Changing the effective focal length and magnification of an imaging system can be accomplished by adeptly positioning two or more active optics in the optical design and appropriately adjusting the optical power of those elements. In this application, the active optics (e.g. liquid crystal spatial light modulators or deformable mirrors) serve as variable focal-length lenses. Unfortunately, the range over which currently available devices can operate (i.e. their dynamic range) is relatively small. Therefore, the key to this concept is to create large changes in the effective focal length of the system with very small changes in the focal lengths of individual elements by leveraging the optical power of conventional optical elements surrounding the active optics. By appropriately designing the optical system, these variable focal-length lenses can provide the flexibility necessary to change the overall system focal length, and therefore magnification, that is normally accomplished with mechanical motion in conventional zoom lenses.

  5. The Cornell High-order Adaptive Optics Survey for Brown Dwarfs in Stellar Systems-I: Observations, Data Reduction, and Detection Analysis

    CERN Document Server

    Carson, J C; Brandl, B R; Wilson, J C; Hayward, T L

    2005-01-01

    In this first of a two-paper sequence, we report techniques and results of the Cornell High-order Adaptive Optics Survey for brown dwarf companions (CHAOS). At the time of this writing, this study represents the most sensitive published population survey of brown dwarf companions to main sequence stars, for separation akin to our own outer solar system. The survey, conducted using the Palomar 200-inch Hale Telescope, consists of K-short coronagraphic observations of 80 main sequence stars out to 22 parsecs. At 1 arcsecond separations from a typical target system, the survey achieves median sensitivities 10 magnitudes fainter than the parent star. In terms of companion mass, the survey achieves typical sensitivities of 25 Jupiter masses (1 Gyr), 50 Jupiter masses (solar age), and 60 Jupiter masses (10 Gyr), using evolutionary models of Baraffe et al. (2003). Using common proper motion to distinguish companions from field stars, we find that no systems show positive evidence of a substellar companion (searchabl...

  6. HIGH-EFFICIENCY AUTONOMOUS LASER ADAPTIVE OPTICS

    Energy Technology Data Exchange (ETDEWEB)

    Baranec, Christoph [Institute for Astronomy, University of Hawai' i at Mānoa, Hilo, HI, NZ 96720-2700 (United States); Riddle, Reed; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Dekany, Richard; Kulkarni, Shrinivas [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Law, Nicholas M. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255 (United States); Ramaprakash, A. N.; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Punnadi, Sujit, E-mail: baranec@hawaii.edu [Inter-University Centre for Astronomy and Astrophysics, Ganeshkhind, Pune 411007 (India)

    2014-07-20

    As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limit their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.

  7. High-efficiency Autonomous Laser Adaptive Optics

    CERN Document Server

    Baranec, Christoph; Law, Nicholas M; Ramaprakash, A N; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Dekany, Richard; Kulkarni, Shrinivas; Punnadi, Sujit

    2014-01-01

    As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limits their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.

  8. The ESO Adaptive Optics Facility

    Science.gov (United States)

    Ströbele, S.; Arsenault, R.; Bacon, R.; Biasi, R.; Bonaccini-Calia, D.; Downing, M.; Conzelmann, R. D.; Delabre, B.; Donaldson, R.; Duchateau, M.; Esposito, S.; Fedrigo, E.; Gallieni, D.; Hackenberg, W. K. P.; Hubin, N.; Kasper, M.; Kissler-Patig, M.; Le Louarn, M.; McDermid, R.; Oberti, S.; Paufique, J.; Riccardi, A.; Stuik, R.; Vernet, E.

    2006-06-01

    The Adaptive Optics Facility is a project to convert one VLT-UT into a specialized Adaptive Telescope. The present secondary mirror (M2) will be replaced by a new M2-Unit hosting a 1170 actuators deformable mirror. The 3 focal stations will be equipped with instruments adapted to the new capability of this UT. Two instruments are in development for the 2 Nasmyth foci: Hawk-I with its AO module GRAAL allowing a Ground Layer Adaptive Optics correction and MUSE with GALACSI for GLAO correction and Laser Tomography Adaptive Optics correction. A future instrument still needs to be defined for the Cassegrain focus. Several guide stars are required for the type of adaptive corrections needed and a four Laser Guide Star facility (4LGSF) is being developed in the scope of the AO Facility. Convex mirrors like the VLT M2 represent a major challenge for testing and a substantial effort is dedicated to this. ASSIST, is a test bench that will allow testing of the Deformable Secondary Mirror and both instruments with simulated turbulence. This article describes the Adaptive Optics facility systems composing associated with it.

  9. Adaptive Optics for Large Telescopes

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, S

    2008-06-27

    The use of adaptive optics was originally conceived by astronomers seeking to correct the blurring of images made with large telescopes due to the effects of atmospheric turbulence. The basic idea is to use a device, a wave front corrector, to adjust the phase of light passing through an optical system, based on some measurement of the spatial variation of the phase transverse to the light propagation direction, using a wave front sensor. Although the original concept was intended for application to astronomical imaging, the technique can be more generally applied. For instance, adaptive optics systems have been used for several decades to correct for aberrations in high-power laser systems. At Lawrence Livermore National Laboratory (LLNL), the world's largest laser system, the National Ignition Facility, uses adaptive optics to correct for aberrations in each of the 192 beams, all of which must be precisely focused on a millimeter scale target in order to perform nuclear physics experiments.

  10. Performance of the optical communication adaptive optics testbed

    Science.gov (United States)

    Troy, Mitchell; Roberts, Jennifer; Guiwits, Steve; Azevedo, Steve; Bikkannavar, Siddarayappa; Brack, Gary; Garkanian, Vachik; Palmer, Dean; Platt, Benjamin; Truong, Tuan; Wilson, Keith; Wallace, Kent

    2005-01-01

    We describe the current performance of an adaptive optics testbed for optical communication. This adaptive optics system allows for simulation of night and day-time observing on a 1 meter telescope with a 97 actuator deformable mirror.

  11. A Keck Adaptive Optics Survey of a Representative Sample of Gravitationally-Lensed Star-Forming Galaxies: High Spatial Resolution Studies of Kinematics and Metallicity Gradients

    CERN Document Server

    Leethochawalit, Nicha; Ellis, Richard S; Stark, Daniel P; Richard, Johan; Zitrin, Adi; Auger, Matthew

    2015-01-01

    We discuss spatially resolved emission line spectroscopy secured for a total sample of 15 gravitationally lensed star-forming galaxies at a mean redshift of $z\\simeq2$ based on Keck laser-assisted adaptive optics observations undertaken with the recently-improved OSIRIS integral field unit (IFU) spectrograph. By exploiting gravitationally lensed sources drawn primarily from the CASSOWARY survey, we sample these sub-L$^{\\ast}$ galaxies with source-plane resolutions of a few hundred parsecs ensuring well-sampled 2-D velocity data and resolved variations in the gas-phase metallicity. Such high spatial resolution data offers a critical check on the structural properties of larger samples derived with coarser sampling using multiple-IFU instruments. We demonstrate how serious errors of interpretation can only be revealed through better sampling. Although we include four sources from our earlier work, the present study provides a more representative sample unbiased with respect to emission line strength. Contrary t...

  12. Micromirror Arrays for Adaptive Optics

    Energy Technology Data Exchange (ETDEWEB)

    Carr, E.J.

    2000-08-07

    The long-range goal of this project is to develop the optical and mechanical design of a micromirror array for adaptive optics that will meet the following criteria: flat mirror surface ({lambda}/20), high fill factor (> 95%), large stroke (5-10 {micro}m), and pixel size {approx}-200 {micro}m. This will be accomplished by optimizing the mirror surface and actuators independently and then combining them using bonding technologies that are currently being developed.

  13. Field guide to adaptive optics

    CERN Document Server

    Tyson, Robert K

    2004-01-01

    ""...These field guides will be immensely useful to all scientists and engineers who wish to brush up on authentic definitions, equations, and tables of data in optics. And the format is really user friendly! I...wonder now how I ever got along in optics without this ready reference....a real winner!"" --Dr. Leno S. Pedrotti, Center for Occupational Research and Development (CORD) Third in the Field Guide Series, this is a summary of the methods for determining the requirements of an adaptive optics system, the performance of the system, and the requirements for the components of th

  14. Future trends in adaptive Optics

    Science.gov (United States)

    Le Louarn, Miska

    2001-05-01

    In this talk, I will summarize the limitations of current adaptive optics systems (cone effect, anisoplanatism) and I will show what methods can be used to overcome them. I will focus on Multi-Conjugate AO and the polychromatic laser guide star. I will also address AO for Extremely Large Telescopes (ELTs), such as OWL (ESO) and CELT (University of California / Caltech).

  15. Driver Code for Adaptive Optics

    Science.gov (United States)

    Rao, Shanti

    2007-01-01

    A special-purpose computer code for a deformable-mirror adaptive-optics control system transmits pixel-registered control from (1) a personal computer running software that generates the control data to (2) a circuit board with 128 digital-to-analog converters (DACs) that generate voltages to drive the deformable-mirror actuators. This program reads control-voltage codes from a text file, then sends them, via the computer s parallel port, to a circuit board with four AD5535 (or equivalent) chips. Whereas a similar prior computer program was capable of transmitting data to only one chip at a time, this program can send data to four chips simultaneously. This program is in the form of C-language code that can be compiled and linked into an adaptive-optics software system. The program as supplied includes source code for integration into the adaptive-optics software, documentation, and a component that provides a demonstration of loading DAC codes from a text file. On a standard Windows desktop computer, the software can update 128 channels in 10 ms. On Real-Time Linux with a digital I/O card, the software can update 1024 channels (8 boards in parallel) every 8 ms.

  16. Adaptive optics optical coherence tomography in glaucoma.

    Science.gov (United States)

    Dong, Zachary M; Wollstein, Gadi; Wang, Bo; Schuman, Joel S

    2017-03-01

    Since the introduction of commercial optical coherence tomography (OCT) systems, the ophthalmic imaging modality has rapidly expanded and it has since changed the paradigm of visualization of the retina and revolutionized the management and diagnosis of neuro-retinal diseases, including glaucoma. OCT remains a dynamic and evolving imaging modality, growing from time-domain OCT to the improved spectral-domain OCT, adapting novel image analysis and processing methods, and onto the newer swept-source OCT and the implementation of adaptive optics (AO) into OCT. The incorporation of AO into ophthalmic imaging modalities has enhanced OCT by improving image resolution and quality, particularly in the posterior segment of the eye. Although OCT previously captured in-vivo cross-sectional images with unparalleled high resolution in the axial direction, monochromatic aberrations of the eye limit transverse or lateral resolution to about 15-20 μm and reduce overall image quality. In pairing AO technology with OCT, it is now possible to obtain diffraction-limited resolution images of the optic nerve head and retina in three-dimensions, increasing resolution down to a theoretical 3 μm(3). It is now possible to visualize discrete structures within the posterior eye, such as photoreceptors, retinal nerve fiber layer bundles, the lamina cribrosa, and other structures relevant to glaucoma. Despite its limitations and barriers to widespread commercialization, the expanding role of AO in OCT is propelling this technology into clinical trials and onto becoming an invaluable modality in the clinician's arsenal. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Robotic visible-light laser adaptive optics

    Science.gov (United States)

    Baranec, Christoph; Riddle, Reed; Law, Nicholas; Ramaprakash, A. N.; Tendulkar, Shriharsh; Bui, Khanh; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Dekany, Richard; Kulkarni, Shrinivas; Punnadi, Sujit

    2013-12-01

    Robo-AO is the first autonomous laser adaptive optics system and science instrument operating on sky. With minimal human oversight, the system robotically executes large scale surveys, monitors long-term astrophysical dynamics and characterizes newly discovered transients, all at the visible diffraction limit. The adaptive optics setup time, from the end of the telescope slew to the beginning of an observation, is a mere ~50-60 s, enabling over 200 observations per night. The first of many envisioned systems has finished 58 nights of science observing at the Palomar Observatory 60-inch (1.5 m) telescope, with over 6,400 robotic observations executed thus far. The system will be augmented in late 2013 with a low-noise wide field infrared camera, which doubles as a tip-tilt sensor, to widen the spectral bandwidth of observations and increase available sky coverage while also enabling deeper visible imaging using adaptive-optics sharpened infrared tip-tilt guide sources. Techniques applicable to larger telescope systems will also be tested: the infrared camera will be used to demonstrate advanced multiple region-of-interest tip-tilt guiding methods, and a visitor instrument port will be used for evaluation of other instrumentation, e.g. single-mode and photonic fibers to feed compact spectrographs.

  18. ERIS adaptive optics system design

    Science.gov (United States)

    Marchetti, Enrico; Le Louarn, Miska; Soenke, Christian; Fedrigo, Enrico; Madec, Pierre-Yves; Hubin, Norbert

    2012-07-01

    The Enhanced Resolution Imager and Spectrograph (ERIS) is the next-generation instrument planned for the Very Large Telescope (VLT) and the Adaptive Optics facility (AOF). It is an AO assisted instrument that will make use of the Deformable Secondary Mirror and the new Laser Guide Star Facility (4LGSF), and it is planned for the Cassegrain focus of the telescope UT4. The project is currently in its Phase A awaiting for approval to continue to the next phases. The Adaptive Optics system of ERIS will include two wavefront sensors (WFS) to maximize the coverage of the proposed sciences cases. The first is a high order 40x40 Pyramid WFS (PWFS) for on axis Natural Guide Star (NGS) observations. The second is a high order 40x40 Shack-Hartmann WFS for single Laser Guide Stars (LGS) observations. The PWFS, with appropriate sub-aperture binning, will serve also as low order NGS WFS in support to the LGS mode with a field of view patrolling capability of 2 arcmin diameter. Both WFSs will be equipped with the very low read-out noise CCD220 based camera developed for the AOF. The real-time reconstruction and control is provided by a SPARTA real-time platform adapted to support both WFS modes. In this paper we will present the ERIS AO system in all its main aspects: opto-mechanical design, real-time computer design, control and calibrations strategy. Particular emphasis will be given to the system performance obtained via dedicated numerical simulations.

  19. Adaptive multilayer optics for extreme ultraviolet wavelengths

    NARCIS (Netherlands)

    Bayraktar, Muharrem

    2015-01-01

    In this thesis we describe the development of a new class of optical components to enhance the imaging performance by enabling adaptations of the optics. When used at extreme ultraviolet (EUV) wavelengths, such ‘adaptive optics’ offers the potential to achieve the highest spatial resolution in imagi

  20. Initial concepts for CELT adaptive optics

    Science.gov (United States)

    Dekany, Richard G.; Bauman, Brian J.; Gavel, Donald T.; Troy, Mitchell; Macintosh, Bruce A.; Britton, Matthew C.

    2003-02-01

    The California Extremely Large Telescope (CELT) project has recently completed a 12-month conceptual design phase that has investigated major technology challenges in a number of Observatory subsystems, including adaptive optics (AO). The goal of this effort was not to adopt one or more specific AO architectures. Rather, it was to investigate the feasibility of adaptive optics correction of a 30-meter diameter telescope and to suggest realistic cost ceilings for various adaptive optics capabilities. We present here the key design issues uncovered during conceptual design and present two non-exclusive ‘baseline" adaptive optics concepts that are expected to be further developed during the following preliminary design phase. Further analysis, detailed engineering trade studies, and certain laboratory and telescope experiments must be performed, and key component technology prototypes demonstrated, prior to adopting one or more adaptive optics systems architectures for realization.

  1. Adaptive optics imaging of the retina.

    Science.gov (United States)

    Battu, Rajani; Dabir, Supriya; Khanna, Anjani; Kumar, Anupama Kiran; Roy, Abhijit Sinha

    2014-01-01

    Adaptive optics is a relatively new tool that is available to ophthalmologists for study of cellular level details. In addition to the axial resolution provided by the spectral-domain optical coherence tomography, adaptive optics provides an excellent lateral resolution, enabling visualization of the photoreceptors, blood vessels and details of the optic nerve head. We attempt a mini review of the current role of adaptive optics in retinal imaging. PubMed search was performed with key words Adaptive optics OR Retina OR Retinal imaging. Conference abstracts were searched from the Association for Research in Vision and Ophthalmology (ARVO) and American Academy of Ophthalmology (AAO) meetings. In total, 261 relevant publications and 389 conference abstracts were identified.

  2. Adaptive optics imaging of the retina

    Directory of Open Access Journals (Sweden)

    Rajani Battu

    2014-01-01

    Full Text Available Adaptive optics is a relatively new tool that is available to ophthalmologists for study of cellular level details. In addition to the axial resolution provided by the spectral-domain optical coherence tomography, adaptive optics provides an excellent lateral resolution, enabling visualization of the photoreceptors, blood vessels and details of the optic nerve head. We attempt a mini review of the current role of adaptive optics in retinal imaging. PubMed search was performed with key words Adaptive optics OR Retina OR Retinal imaging. Conference abstracts were searched from the Association for Research in Vision and Ophthalmology (ARVO and American Academy of Ophthalmology (AAO meetings. In total, 261 relevant publications and 389 conference abstracts were identified.

  3. Binocular adaptive optics visual simulator.

    Science.gov (United States)

    Fernández, Enrique J; Prieto, Pedro M; Artal, Pablo

    2009-09-01

    A binocular adaptive optics visual simulator is presented. The instrument allows for measuring and manipulating ocular aberrations of the two eyes simultaneously, while the subject performs visual testing under binocular vision. An important feature of the apparatus consists on the use of a single correcting device and wavefront sensor. Aberrations are controlled by means of a liquid-crystal-on-silicon spatial light modulator, where the two pupils of the subject are projected. Aberrations from the two eyes are measured with a single Hartmann-Shack sensor. As an example of the potential of the apparatus for the study of the impact of the eye's aberrations on binocular vision, results of contrast sensitivity after addition of spherical aberration are presented for one subject. Different binocular combinations of spherical aberration were explored. Results suggest complex binocular interactions in the presence of monochromatic aberrations. The technique and the instrument might contribute to the better understanding of binocular vision and to the search for optimized ophthalmic corrections.

  4. Progress on the VLT Adaptive Optics Facility

    Science.gov (United States)

    Arsenault, R.; Madec, P.-Y.; Paufique, J.; Ströbele, S.; Pirard, J.-F.; Vernet, É.; Hackenberg, W.; Hubin, N.; Jochum, L.; Kuntschner, H.; Glindemann, A.; Amico, P.; Lelouarn, M.; Kolb, J.; Tordo, S.; Donaldson, R.; Sã¶Nke, C.; Bonaccini Calia, D.; Conzelmann, R.; Delabre, B.; Kiekebusch, M.; Duhoux, P.; Guidolin, I.; Quattri, M.; Guzman, R.; Buzzoni, B.; Comin, M.; Dupuy, C.; Quentin, J.; Lizon, J.-L.; Silber, A.; Jolly, P.; Manescau, A.; Hammersley, P.; Reyes, J.; Jost, A.; Duchateau, M.; Heinz, V.; Bechet, C.; Stuik, R.

    2010-12-01

    The Very Large Telescope (VLT) Adaptive Optics Facility is a project that will transform one of the VLT's Unit Telescopes into an adaptive telescope that includes a deformable mirror in its optical train. For this purpose the secondary mirror is to be replaced by a thin shell deformable mirror; it will be possible to launch four laser guide stars from the centrepiece and two adaptive optics modules are being developed to feed the instruments HAWK-I and MUSE. These modules implement innovative correction modes for seeing improvement through ground layer adaptive optics and, for high Strehl ratio performance, laser tomography adaptive correction. The performance of these modes will be tested in Europe with a custom test bench called ASSIST. The project has completed its final design phase and concluded an intense phase of procurement; the year 2011 will see the beginning of assembly, integration and tests.

  5. On the possibility of intraocular adaptive optics.

    Science.gov (United States)

    Vdovin, Gleb; Loktev, Mikhail; Naumov, Alexander

    2003-04-07

    We consider the technical possibility of an adaptive contact lens and an adaptive eye lens implant based on the modal liquid crystal wavefront corrector, aimed to correct the accommodation loss and higher-order aberrations of the human eye. Our first demonstrator with 5 mm optical aperture is capable of changing the focusing power in the range of 0 to +3 diopters and can be controlled via a wireless capacitive link. These properties make the corrector potentially suitable for implantation into the human eye or for use as an adaptive contact lens. We also discuss possible feedback strategies, aimed to improve visual acuity and to achieve supernormal vision with implantable adaptive optics.

  6. Teaching Optics and Systems Engineering With Adaptive Optics Workbenches

    CERN Document Server

    Harrington, David; Hunter, Lisa; Max, Claire; Hoffmann, Mark; Pitts, Mark; Armstrong, J D

    2010-01-01

    Adaptive optics workbenches are fully functional optical systems that can be used to illustrate and teach a variety of concepts and cognitive processes. Four systems have been funded, designed and constructed by various institutions and people as part of education programs associated with the Center for Adaptive Optics, the Professional Development Program and the Institute for Science and Engineer Educators. Activities can range from first-year undergraduate explorations to professional level training. These workbenches have been used in many venues including the Center for Adaptive Optics AO Summer School, the Maui Community College hosted Akamai Maui Short Course, classrooms, training of new staff in laboratories and other venues. The activity content has focused on various elements of systems thinking, characterization, feedback and system control, basic optics and optical alignment as well as advanced topics such as phase conjugation, wave-front sensing and correction concepts and system design. The work...

  7. A Miniaturized Adaptive Optic Device for Optical Telecommunications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To advance the state-of-the-art uplink laser communication technology, new adaptive optic beam compensation techniques are needed for removing various time-varying...

  8. Optical ballast and adaptive dynamic stable resonator

    Institute of Scientific and Technical Information of China (English)

    Zhang Guang-Yin; Jiao Zhi-Yong; Guo Shu-Guang; Zhang Xiao-Hua; Gu Xue-Wen; Yan Cai-Fan; Wu Ding-Er; Song Feng

    2004-01-01

    In this paper a new concept of ‘optical ballast' is put forward. Optical ballast is a kind of device that can be used to decrease the variation and fluctuation of the propagation characteristics of light beams caused by the disturbance of refractive index of the medium. To illustrate the idea clearly and concretely, a fully adaptive dynamic stable solid-state laser resonator is presented as application example of optical ballast.

  9. Adaptive Optics for Industry and Medicine

    Science.gov (United States)

    Dainty, Christopher

    2008-01-01

    pt. 1. Wavefront correctors and control. Liquid crystal lenses for correction of presbyopia (Invited Paper) / Guoqiang Li and Nasser Peyghambarian. Converging and diverging liquid crystal lenses (oral paper) / Andrew X. Kirby, Philip J. W. Hands, and Gordon D. Love. Liquid lens technology for miniature imaging systems: status of the technology, performance of existing products and future trends (invited paper) / Bruno Berge. Carbon fiber reinforced polymer deformable mirrors for high energy laser applications (oral paper) / S. R. Restaino ... [et al.]. Tiny multilayer deformable mirrors (oral paper) / Tatiana Cherezova ... [et al.]. Performance analysis of piezoelectric deformable mirrors (oral paper) / Oleg Soloviev, Mikhail Loktev and Gleb Vdovin. Deformable membrane mirror with high actuator density and distributed control (oral paper) / Roger Hamelinck ... [et al.]. Characterization and closed-loop demonstration of a novel electrostatic membrane mirror using COTS membranes (oral paper) / David Dayton ... [et al.]. Electrostatic micro-deformable mirror based on polymer materials (oral paper) / Frederic Zamkotsian ... [et al.]. Recent progress in CMOS integrated MEMS A0 mirror development (oral paper) / A. Gehner ... [et al.]. Compact large-stroke piston-tip-tilt actuator and mirror (oral paper) / W. Noell ... [et al.]. MEMS deformable mirrors for high performance AO applications (oral paper) / Paul Bierden, Thomas Bifano and Steven Cornelissen. A versatile interferometric test-rig for the investigation and evaluation of ophthalmic AO systems (poster paper) / Steve Gruppetta, Jiang Jian Zhong and Luis Diaz-Santana. Woofer-tweeter adaptive optics (poster paper) / Thomas Farrell and Chris Dainty. Deformable mirrors based on transversal piezoeffect (poster paper) / Gleb Vdovin, Mikhail Loktev and Oleg Soloviev. Low-cost spatial light modulators for ophthalmic applications (poster paper) / Vincente Durán ... [et al.]. Latest MEMS DM developments and the path ahead

  10. Adaptive Optics at Lawrence Livermore National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Gavel, D T

    2003-03-10

    Adaptive optics enables high resolution imaging through the atmospheric by correcting for the turbulent air's aberrations to the light waves passing through it. The Lawrence Livermore National Laboratory for a number of years has been at the forefront of applying adaptive optics technology to astronomy on the world's largest astronomical telescopes, in particular at the Keck 10-meter telescope on Mauna Kea, Hawaii. The technology includes the development of high-speed electrically driven deformable mirrors, high-speed low-noise CCD sensors, and real-time wavefront reconstruction and control hardware. Adaptive optics finds applications in many other areas where light beams pass through aberrating media and must be corrected to maintain diffraction-limited performance. We describe systems and results in astronomy, medicine (vision science), and horizontal path imaging, all active programs in our group.

  11. The Adaptive Optics Summer School Laboratory Activities

    CERN Document Server

    Ammons, S Mark; Armstrong, J D; Crossfield, Ian; Do, Tuan; Fitzgerald, Mike; Harrington, David; Hickenbotham, Adam; Hunter, Jennifer; Johnson, Jess; Johnson, Luke; Li, Kaccie; Lu, Jessica; Maness, Holly; Morzinski, Katie; Norton, Andrew; Putnam, Nicole; Roorda, Austin; Rossi, Ethan; Yelda, Sylvana

    2011-01-01

    Adaptive Optics (AO) is a new and rapidly expanding field of instrumentation, yet astronomers, vision scientists, and general AO practitioners are largely unfamiliar with the root technologies crucial to AO systems. The AO Summer School (AOSS), sponsored by the Center for Adaptive Optics, is a week-long course for training graduate students and postdoctoral researchers in the underlying theory, design, and use of AO systems. AOSS participants include astronomers who expect to utilize AO data, vision scientists who will use AO instruments to conduct research, opticians and engineers who design AO systems, and users of high-bandwidth laser communication systems. In this article we describe new AOSS laboratory sessions implemented in 2006-2009 for nearly 250 students. The activity goals include boosting familiarity with AO technologies, reinforcing knowledge of optical alignment techniques and the design of optical systems, and encouraging inquiry into critical scientific questions in vision science using AO sys...

  12. Adaptive optics applications in vision science

    Science.gov (United States)

    Olivier, Scot S.

    2003-06-01

    Adaptive optics can be used to correct the aberrations in the human eye caused by imperfections in the cornea and the lens and thereby, improve image quality both looking into and out of the eye. Under the auspices of the NSF Center for Adaptive Optics and the DOE Biomedical Engineering Program, Lawrence Livermore National Laboratory has joined together with leading vision science researchers around the country to develop and test new ophthalmic imaging systems using novel wavefront corrector technologies. Results of preliminary comparative evaluations of these technologies in initial system tests show promise for future clinical utility.

  13. Adaptive Optics Simulations for Siding Spring

    CERN Document Server

    Goodwin, Michael; Lambert, Andrew

    2012-01-01

    Using an observational derived model optical turbulence profile (model-OTP) we have investigated the performance of Adaptive Optics (AO) at Siding Spring Observatory (SSO), Australia. The simulations cover the performance for AO techniques of single conjugate adaptive optics (SCAO), multi-conjugate adaptive optics (MCAO) and ground-layer adaptive optics (GLAO). The simulation results presented in this paper predict the performance of these AO techniques as applied to the Australian National University (ANU) 2.3 m and Anglo-Australian Telescope (AAT) 3.9 m telescopes for astronomical wavelength bands J, H and K. The results indicate that AO performance is best for the longer wavelengths (K-band) and in the best seeing conditions (sub 1-arcsecond). The most promising results are found for GLAO simulations (field of view of 180 arcsecs), with the field RMS for encircled energy 50% diameter (EE50d) being uniform and minimally affected by the free-atmosphere turbulence. The GLAO performance is reasonably good over...

  14. Deep imaging survey of the environment of Alpha Centauri - I. Adaptive optics imaging of Alpha Cen B with VLT-NACO

    CERN Document Server

    Kervella, P; Foresto, V C D; Kervella, Pierre; Th\\'{e}venin, Fr\\'{e}d\\'{e}ric; Foresto, Vincent Coud\\'{e} Du

    2006-01-01

    Context: Alpha Centauri is our closest stellar neighbor, at a distance of only 1.3 pc, and its two main components have spectral types comparable to the Sun. This is therefore a favorable target for an imaging search for extrasolar planets. Moreover, indications exist that the gravitational mass of Alpha Cen B is higher than its modeled mass, the difference being consistent with a substellar companion of a few tens of Jupiter masses. Aims: We searched for faint comoving companions to Alpha Cen B. As a secondary objective, we built a catalogue of the detected background sources. Methods: We used the NACO adaptive optics system of the VLT in the J, H, and Ks bands to search for companions to Alpha Cen B. This instrument allowed us to achieve a very high sensitivity to point-like sources, with a limiting magnitude of m\\_Ks ~ 18 at 7" from the star. We complemented this data set with archival coronagraphic images from the HST-ACS instrument to obtain an accurate astrometric calibration. Results: Over the observed...

  15. Adaptive optical antennas: design and evaluation

    Science.gov (United States)

    Weyrauch, Thomas; Vorontsov, Mikhail A.; Carhart, Gary W.; Simonova, Galina V.; Beresnev, Leonid A.; Polnau, Ernst E.

    2007-09-01

    We present the design and evaluation of compact adaptive optical antennas with apertures diameters of 16 mm and 100 mm for 5Gbit/s-class free-space optical communication systems. The antennas provide a bi-directional optically transparent link between fiber-optical wavelength-division multiplex systems and allow for mitigation of atmospheric-turbulence induced wavefront phase distortions with adaptive optics components. Beam steering is implemented in the antennas either with mirrors on novel tip/tilt platforms or a fiber-tip positioning system, both enabling operation bandwidths of more than 1 kHz. Bimorph piezoelectric actuated deformable mirrors are used for low-order phase-distortion compensation. An imaging system is integrated in the antennas for coarse pointing and tracking. Beam steering and wavefront control is based on blind maximization of the received signal level using a stochastic parallel gradient descent algorithm. The adaptive optics control architecture allowed the use of feedback signals provided locally within each transceiver system and remotely by the opposite transceiver system via an RF link. First atmospheric compensation results from communication experiments over a 250 m near-ground propagation path are presented.

  16. Pulse front control with adaptive optics

    Science.gov (United States)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The focusing of ultrashort laser pulses is extremely important for processes including microscopy, laser fabrication and fundamental science. Adaptive optic elements, such as liquid crystal spatial light modulators or membrane deformable mirrors, are routinely used for the correction of aberrations in these systems, leading to improved resolution and efficiency. Here, we demonstrate that adaptive elements used with ultrashort pulses should not be considered simply in terms of wavefront modification, but that changes to the incident pulse front can also occur. We experimentally show how adaptive elements may be used to engineer pulse fronts with spatial resolution.

  17. Optical axis jitter rejection for double overlapped adaptive optics systems

    Science.gov (United States)

    Luo, Qi; Luo, Xi; Li, Xinyang

    2016-04-01

    Optical axis jitters, or vibrations, which arise from wind shaking and structural oscillations of optical platforms, etc., cause a deleterious impact on the performance of adaptive optics systems. When conventional integrators are utilized to reject such high frequency and narrow-band disturbance, the benefits are quite small despite their acceptable capabilities to reject atmospheric turbulence. In our case, two suits of complete adaptive optics systems called double overlapped adaptive optics systems (DOAOS) are used to counteract both optical jitters and atmospheric turbulence. A novel algorithm aiming to remove vibrations is proposed by resorting to combine the Smith predictor and notch filer. With the help of loop shaping method, the algorithm will lead to an effective and stable controller, which makes the characteristics of error transfer function close to notch filters. On the basis of the spectral analysis of observed data, the peak frequency and bandwidth of vibrations can be identified in advance. Afterwards, the number of notch filters and their parameters will be determined using coordination descending method. The relationship between controller parameters and filtering features is discussed, and the robustness of the controller against varying parameters of the control object is investigated. Preliminary experiments are carried out to validate the proposed algorithms. The overall control performance of DOAOS is simulated. Results show that time delays are a limit of the performance, but the algorithm can be successfully implemented on our systems, which indicate that it has a great potential to reject jitters.

  18. Teaching Optics and Systems Engineering With Adaptive Optics Workbenches

    Science.gov (United States)

    Harrington, D. M.; Ammons, M.; Hunter, L.; Max, C.; Hoffmann, M.; Pitts, M.; Armstrong, J. D.

    2010-12-01

    Adaptive optics workbenches are fully functional optical systems that can be used to illustrate and teach a variety of concepts and cognitive processes. Four systems have been funded, designed and constructed by various institutions and people as part of education programs associated with the Center for Adaptive Optics, the Professional Development Program and the Institute for Scientist & Engineer Educators. Activities can range from first-year undergraduate explorations to professional level training. These workbenches have been used in many venues including the Center for Adaptive Optics AO Summer School, the Maui Community College-hosted Akamai Maui Short Course, classrooms, training of new staff in laboratories and other venues. The activity content has focused on various elements of systems thinking, characterization, feedback and system control, basic optics and optical alignment as well as advanced topics such as phase conjugation, wave-front sensing and correction concepts, and system design. The workbenches have slightly different designs and performance capabilities. We describe here outlines for several activities utilizing these different designs and some examples of common student learner outcomes and experiences.

  19. Development of large aperture composite adaptive optics

    Science.gov (United States)

    Kmetik, Viliam; Vitovec, Bohumil; Jiran, Lukas; Nemcova, Sarka; Zicha, Josef; Inneman, Adolf; Mikulickova, Lenka; Pavlica, Richard

    2015-01-01

    Large aperture composite adaptive optics for laser applications is investigated in cooperation of Institute of Plasma Physic, Department of Instrumentation and Control Engineering FME CTU and 5M Ltd. We are exploring opportunity of a large-size high-power-laser deformable-mirror production using a lightweight bimorph actuated structure with a composite core. In order to produce a sufficiently large operational free aperture we are developing new technologies for production of flexible core, bimorph actuator and deformable mirror reflector. Full simulation of a deformable-mirrors structure was prepared and validated by complex testing. A deformable mirror actuation and a response of a complicated structure are investigated for an accurate control of the adaptive optics. An original adaptive optics control system and a bimorph deformable mirror driver were developed. Tests of material samples, components and sub-assemblies were completed. A subscale 120 mm bimorph deformable mirror prototype was designed, fabricated and thoroughly tested. A large-size 300 mm composite-core bimorph deformable mirror was simulated and optimized, fabrication of a prototype is carried on. A measurement and testing facility is modified to accommodate large sizes optics.

  20. Adaptive optics implementation with a Fourier reconstructor.

    Science.gov (United States)

    Glazer, Oded; Ribak, Erez N; Mirkin, Leonid

    2007-02-01

    Adaptive optics takes its servo feedback error cue from a wavefront sensor. The common Hartmann-Shack spot grid that represents the wavefront slopes is usually analyzed by finding the spot centroids. In a novel application, we used the Fourier decomposition of a spot pattern to find deviations from grid regularity. This decomposition was performed either in the Fourier domain or in the image domain, as a demodulation of the grid of spots. We analyzed the system, built a control loop for it, and tested it thoroughly. This allowed us to close the loop on wavefront errors caused by turbulence in the optical system.

  1. [Technical principles of adaptive optics in ophthalmology].

    Science.gov (United States)

    Reiniger, J L; Domdei, N; Holz, F G; Harmening, W M

    2017-02-13

    During the last 25 years ophthalmic imaging has undergone a revolution. This review gives an overview of the possibilities of adaptive optics (AO) for ophthalmic imaging technologies and their development and illustrates that the role of ophthalmic imaging changed from the documentation of obvious abnormalities to the detection of microscopic yet significant conspicuities. This enables earlier and more precise diagnoses. The implementation of AO for imaging systems like fundus cameras, scanning laser ophthalmoscopy and optical coherence tomography has gained in importance. In recent years a couple of companies started developing commercially available AO systems, thus, indicating a future use in clinical routine.

  2. Optical Property Analyses of Plant Cells for Adaptive Optics Microscopy

    Science.gov (United States)

    Tamada, Yosuke; Murata, Takashi; Hattori, Masayuki; Oya, Shin; Hayano, Yutaka; Kamei, Yasuhiro; Hasebe, Mitsuyasu

    2014-04-01

    In astronomy, adaptive optics (AO) can be used to cancel aberrations caused by atmospheric turbulence and to perform diffraction-limited observation of astronomical objects from the ground. AO can also be applied to microscopy, to cancel aberrations caused by cellular structures and to perform high-resolution live imaging. As a step toward the application of AO to microscopy, here we analyzed the optical properties of plant cells. We used leaves of the moss Physcomitrella patens, which have a single layer of cells and are thus suitable for optical analysis. Observation of the cells with bright field and phase contrast microscopy, and image degradation analysis using fluorescent beads demonstrated that chloroplasts provide the main source of optical degradations. Unexpectedly, the cell wall, which was thought to be a major obstacle, has only a minor effect. Such information provides the basis for the application of AO to microscopy for the observation of plant cells.

  3. Radio-Optical Imaging of ATLBS Survey

    Indian Academy of Sciences (India)

    Kshitij Thorat

    2011-12-01

    We present the radio-optical imaging of ATLBS, a sensitive radio survey (Subrahmanyan et al. 2010). The primary aim of the ATLBS survey is to image low-power radio sources which form the bulk of the radio source population to moderately high red-shifts ( ∼ 1.0). The accompanying multiband optical and near infra-red observations provide information about the hosts and environments of the radio sources. We give here details of the imaging of the radio data and optical data for the ATLBS survey.

  4. Extragalactic Fields Optimized for Adaptive Optics

    Science.gov (United States)

    2011-03-01

    DAVID MONETIO Received 2010 luly 19; accepted 2010 December 30; published 2011 March 1 ABSTRACT. In this article we present the coordinates of 67 55’ x...fields. In some cases adaptive optics observations undertaken in the fields given in this article would be orders of magnitude more efficient than...expectations of considerable pro- gress in this subject with the advent of 30 m class extremely large telescopes ( ELTs ). A basic problem with unde1taking

  5. Thermo-optically driven adaptive mirror

    Science.gov (United States)

    Reinert, Felix; Lüthy, Willy

    2006-02-01

    The ideal adaptive optical mirror combines large aperture with high spatial and temporal resolution and a phase shift of at least 2π. Further, a simple low-cost solution is preferred. No adaptive system can perfectly fulfill all these requirements. We present a system that has the potential to reach this goal with the exception of high temporal resolution. But even with a moderate temporal resolution of one second such a system can find practical applications. For example as a laser resonator mirror that allows to modify the intensity distribution of the emission, or to correct slowly varying aberrations of optical systems. Two possible mechanisms can be used to change the optical path length of the adaptive mirror: thermal expansion of the mirror substrate or the thermally induced change of the refractive index (thermal dispersion) of a medium in front of the mirror. Both mechanisms have been shown to lead to promising results. In both cases heating was performed by irradiation of light in the active medium. The thermal dispersion based adaptive mirror is built with a thin layer of a liquid in front of a mirror. To allow a modification of the refractive index by irradiation with a diode laser at 808 nm, a suitable absorber is dissolved in the water. With chopped irradiation a resolution of 3.8 Hz at 30 % contrast is measured. This mirror has been used in a laser resonator to modify the output distribution of the laser. The thermal expansion based adaptive mirror is built with a thin layer of a silicon elastomer with a gold coated front side. We present a preparation method to produce thin films of Sylgard on sapphire. With an irradiated intensity of only 370 mW/cm2 surface modulations of up to 350 nm are obtained. With a test pattern a resolution of 1.6 line-pairs per millimeter at 30 % contrast is measured. The temporal resolution is better than one second.

  6. Adaptive optics optical coherence tomography for retina imaging

    Institute of Scientific and Technical Information of China (English)

    Guohua Shi; Yun Dai; Ling Wang; Zhihua Ding; Xuejun Rao; Yudong Zhang

    2008-01-01

    When optical coherence tomography (OCT) is used for human retina imaging, its transverse resolution is limited by the aberrations of human eyes. To overcome this disadvantage, a high resolution imaging system for living human retina, which consists of a time domain OCT system and a 37-elements adaptive optics (AO) system, has been developed. The AO closed loop rate is 20 frames per second, and the OCT has a 6.7-μm axial resolution. In this paper, this system is introduced and the high resolution imaging results for retina are presented.

  7. Reflective afocal broadband adaptive optics scanning ophthalmoscope

    Science.gov (United States)

    Dubra, Alfredo; Sulai, Yusufu

    2011-01-01

    A broadband adaptive optics scanning ophthalmoscope (BAOSO) consisting of four afocal telescopes, formed by pairs of off-axis spherical mirrors in a non-planar arrangement, is presented. The non-planar folding of the telescopes is used to simultaneously reduce pupil and image plane astigmatism. The former improves the adaptive optics performance by reducing the root-mean-square (RMS) of the wavefront and the beam wandering due to optical scanning. The latter provides diffraction limited performance over a 3 diopter (D) vergence range. This vergence range allows for the use of any broadband light source(s) in the 450-850 nm wavelength range to simultaneously image any combination of retinal layers. Imaging modalities that could benefit from such a large vergence range are optical coherence tomography (OCT), multi- and hyper-spectral imaging, single- and multi-photon fluorescence. The benefits of the non-planar telescopes in the BAOSO are illustrated by resolving the human foveal photoreceptor mosaic in reflectance using two different superluminescent diodes with 680 and 796 nm peak wavelengths, reaching the eye with a vergence of 0.76 D relative to each other. PMID:21698035

  8. Overview of Advanced LIGO Adaptive Optics

    CERN Document Server

    Brooks, Aidan F; Arain, Muzammil A; Ciani, Giacomo; Cole, Ayodele; Grabeel, Greg; Gustafson, Eric; Guido, Chris; Heintze, Matthew; Heptonstall, Alastair; Jacobson, Mindy; Kim, Won; King, Eleanor; Lynch, Alexander; O'Connor, Stephen; Ottaway, David; Mailand, Ken; Mueller, Guido; Munch, Jesper; Sannibale, Virginio; Shao, Zhenhua; Smith, Michael; Veitch, Peter; Vo, Thomas; Vorvick, Cheryl; Willems, Phil

    2016-01-01

    This is an overview of the adaptive optics used in Advanced LIGO (aLIGO), known as the thermal compensation system (TCS). The thermal compensation system was designed to minimize thermally-induced spatial distortions in the interferometer optical modes and to provide some correction for static curvature errors in the core optics of aLIGO. The TCS is comprised of ring heater actuators, spatially tunable CO$_{2}$ laser projectors and Hartmann wavefront sensors. The system meets the requirements of correcting for nominal distortion in Advanced LIGO to a maximum residual error of 5.4nm, weighted across the laser beam, for up to 125W of laser input power into the interferometer.

  9. Adaptive Optics for Fluorescence Correlation Spectroscopy

    CERN Document Server

    Leroux, Charles Edouard; Derouard, Jacques; Delon, Antoine

    2011-01-01

    Fluorescence Correlation Spectroscopy (FCS) yields measurement parameters (number of molecules, diffusion time) that characterize the concentration and kinetics of fluorescent molecules within a supposedly known observation volume. Absolute derivation of concentrations and diffusion constants therefore requires preliminary calibrations of the confocal Point Spread Function with phantom solutions under perfectly controlled environmental conditions. In this paper, we quantify the influence of optical aberrations on single photon FCS and demonstrate a simple Adaptive Optics system for aberration correction. Optical aberrations are gradually introduced by focussing the excitation laser beam at increasing depths in fluorescent solutions with various refractive indices, which leads to drastic depth-dependent bias in the estimated FCS parameters. Aberration correction with a Deformable Mirror stabilizes these parameters within a range of several tens of \\mum into the solution. We also demonstrate, both theoretically...

  10. Adaptive optics scanning ophthalmoscopy with annular pupils.

    Science.gov (United States)

    Sulai, Yusufu N; Dubra, Alfredo

    2012-07-01

    Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections.

  11. The CLASS blazar survey - II. Optical properties

    NARCIS (Netherlands)

    Caccianiga, A; Marcha, MJ; Anton, S; Mack, KH; Neeser, MJ

    2002-01-01

    This paper presents the optical properties of the objects selected in the CLASS blazar survey. Because an optical spectrum is now available for 70 per cent of the 325 sources present in the sample, a spectral classification, based on the appearance of the emission/absorption lines, is possible. A wi

  12. The CLASS blazar survey - II. Optical properties

    NARCIS (Netherlands)

    Caccianiga, A; Marcha, MJ; Anton, S; Mack, KH; Neeser, MJ

    2002-01-01

    This paper presents the optical properties of the objects selected in the CLASS blazar survey. Because an optical spectrum is now available for 70 per cent of the 325 sources present in the sample, a spectral classification, based on the appearance of the emission/absorption lines, is possible. A

  13. The CHARA Array Adaptive Optics Program

    Science.gov (United States)

    Ten Brummelaar, Theo; Che, Xiao; McAlister, Harold A.; Ireland, Michael; Monnier, John D.; Mourard, Denis; Ridgway, Stephen T.; sturmann, judit; Sturmann, Laszlo; Turner, Nils H.; Tuthill, Peter

    2016-01-01

    The CHARA array is an optical/near infrared interferometer consisting of six 1-meter diameter telescopes the longest baseline of which is 331 meters. With sub-millisecond angular resolution, the CHARA array is able to spatially resolve nearby stellar systems to reveal the detailed structures. To improve the sensitivity and scientific throughput, the CHARA array was funded by NSF-ATI in 2011, and by NSF-MRI in 2015, for an upgrade of adaptive optics (AO) systems to all six telescopes. The initial grant covers Phase I of the adaptive optics system, which includes an on-telescope Wavefront Sensor and non-common-path (NCP) error correction. The WFS use a fairly standard Shack-Hartman design and will initially close the tip tilt servo and log wavefront errors for use in data reduction and calibration. The second grant provides the funding for deformable mirrors for each telescope which will be used closed loop to remove atmospheric aberrations from the beams. There are then over twenty reflections after the WFS at the telescopes that bring the light several hundred meters into the beam combining laboratory. Some of these, including the delay line and beam reducing optics, are powered elements, and some of them, in particular the delay lines and telescope Coude optics, are continually moving. This means that the NCP problems in an interferometer are much greater than those found in more standard telescope systems. A second, slow AO system is required in the laboratory to correct for these NCP errors. We will breifly describe the AO system, and it's current status, as well as discuss the new science enabled by the system with a focus on our YSO program.

  14. The ESO Adaptive Optics Facility under Test

    Science.gov (United States)

    Arsenault, Robin; Madec, Pierre-Yves; Paufique, Jerome; La Penna, Paolo; Stroebele, Stefan; Vernet, Elise; Pirard, Jean-François; Hackenberg, Wolfgang; Kuntschner, Harald; Kolb, Johann; Muller, Nicolas; Le Louarn, Miska; Amico, Paola; Hubin, Norbert; Lizon, Jean-Louis; Ridings, Rob; Abad, Jose; Fischer, Gert; Heinz, Volker; Kiekebusch, Mario; Argomedo, Javier; Conzelmann, Ralf; Tordo, Sebastien; Donaldson, Rob; Soenke, Christian; Duhoux, Philippe; Fedrigo, Enrico; Delabre, Bernard; Jost, Andrea; Duchateau, Michel; Downing, Mark; Moreno, Javier; Manescau, Antonio; Bonaccini Calia, Domenico; Quattri, Marco; Dupuy, Christophe; Guidolin, Ivan; Comin, Mauro; Guzman, Ronald; Buzzoni, Bernard; Quentin, Jutta; Lewis, Steffan; Jolley, Paul; Kraus, Max; Pfrommer, Thomas; Garcia-Rissmann, Aurea; Biasi, Roberto; Gallieni, Daniele; Stuik, Remko

    2013-12-01

    The Adaptive Optics Facility project has received most of its subsystems in Garching and the ESO Integration Hall has become the central operation location for the next phase of the project. The main test bench ASSIST and the 2nd Generation M2-Unit (hosting the Deformable Secondary Mirror) have been granted acceptance late 2012. The DSM will now undergo a series of tests on ASSIST to qualify its optical performance which launches the System Test Phase of the AOF. The tests will validate the AO modules operation with the DSM: first the GRAAL adaptive optics module for Hawk-I in natural guide star AO mode on-axis and then its Ground Layer AO mode. This will be followed by the GALACSI (for MUSE) Wide-Field-Mode (GLAO) and then the more challenging Narrow-Field-Mode (LTAO). We will report on the status of the subsystems at the time of the conference but also on the performance of the delivered ASSIST test bench, the DSM and the 20 Watt Sodium fiber Laser pre-production unit which has validated all specifications before final manufacturing of the serial units. We will also present some considerations and tools to ensure an efficient operation of the Facility in Paranal.

  15. In vivo cellular visualization of the human retina using optical coherence tomography and adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, S S; Jones, S M; Chen, D C; Zawadzki, R J; Choi, S S; Laut, S P; Werner, J S

    2006-01-05

    Optical coherence tomography (OCT) sees the human retina sharply with adaptive optics. In vivo cellular visualization of the human retina at micrometer-scale resolution is possible by enhancing Fourier-domain optical-coherence tomography with adaptive optics, which compensate for the eye's optical aberrations.

  16. Burrell-Optical-Kepler Survey (BOKS) I: Survey Description

    Science.gov (United States)

    Feldmeier, John J.; Howell, S.; Harding, P.; Mihos, C.; Rudick, C.; Sherry, W.; Lee, T.; Knox, C.; Ciardi, D.; von Braun, K.; Everett, M.; Proctor, M.; van Belle, G.

    2006-12-01

    The Burrell Optical Kepler Survey (BOKS) is a ground-based, high cadence, stellar variability survey over a portion of the planned science field for the Kepler mission. The survey was carried out at the 0.6m Burrell Schmidt telescope, with an observed field size of 1.36 square degrees. Over 60,000 stars were observed within the BOKS field in the SDSS r-band spanning a time period of 39 days, with a 4.5 minute cadence. We give a basic description of the survey, and calculate the observability function for stellar variablity of different types.

  17. Progress with the lick adaptive optics system

    Energy Technology Data Exchange (ETDEWEB)

    Gavel, D T; Olivier, S S; Bauman, B; Max, C E; Macintosh, B

    2000-03-01

    Progress and results of observations with the Lick Observatory Laser Guide Star Adaptive Optics System are presented. This system is optimized for diffraction-limited imaging in the near infrared, 1-2 micron wavelength bands. We describe our development efforts in a number of component areas including, a redesign of the optical bench layout, the commissioning of a new infrared science camera, and improvements to the software and user interface. There is also an ongoing effort to characterize the system performance with both natural and laser guide stars and to fold this data into a refined system model. Such a model can be used to help plan future observations, for example, predicting the point-spread function as a function of seeing and guide star magnitude.

  18. Phase sensor for solar adaptive-optics

    CERN Document Server

    Kellerer, Aglae

    2011-01-01

    Wavefront sensing in solar adaptive-optics is currently done with correlating Shack-Hartmann sensors, although the spatial- and temporal-resolutions of the phase measurements are then limited by the extremely fast computing required to correlate the sensor signals at the frequencies of daytime atmospheric-fluctuations. To avoid this limitation, a new wavefront-sensing technique is presented, that makes use of the solar brightness and is applicable to extended sources. The wavefront is sent through a modified Mach-Zehnder interferometer. A small, central part of the wavefront is used as reference and is made to interfere with the rest of the wavefront. The contrast of two simultaneously measured interference-patterns provides a direct estimate of the wavefront phase, no additional computation being required. The proposed optical layout shows precise initial alignment to be the critical point in implementing the new wavefront-sensing scheme.

  19. Design considerations for CELT adaptive optics

    Science.gov (United States)

    Dekany, Richard G.; Nelson, Jerry E.; Bauman, Brian J.

    2000-07-01

    California Institute of Technology and University of California have begun conceptual design studies for a new telescope for astronomical research at visible and infrared wavelengths. The California Extremely Large Telescope (CELT) is currently envisioned as a filled-aperture, steerable, segmented telescope of approximately 30 m diameter. The key to satisfying many of the science goals of this observatory is the availability of diffraction-limited wavefront control. We describe potential observing modes of CELT, including a discussion of the several major outstanding AO system architectural design issues to be resolved prior to the initiation of the detailed design of the adaptive optics capability.

  20. Adaptive Holographic Fiber-Optic Interferometer

    Science.gov (United States)

    Kozhevnikov, Nikolai M.; Lipovskaya, Margarita J.

    1990-04-01

    Interaction of phase-modulated light beams in photorefractive local inertial responce media was analysed. Interaction of this type allows to registrate phase-modulated signals adaptively under low frequency phase disturbtion. The experiments on multimode fiber-optic interferometer with demodulation element based on photorefractive bacteriorhodopsin-doped polimer film are described. As the writing of dynamic phase hologram is an inertial process the signal fluctuations with the frequencies up to 100 Hz can be canceled. The hologram efficiencies are enough to registrate high frequency phase shifts ~10-4 radn.

  1. Adaptive optics and laser guide stars at Lick observatory

    Energy Technology Data Exchange (ETDEWEB)

    Brase, J.M. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    For the past several years LLNL has been developing adaptive optics systems for correction of both atmospheric turbulence effects and thermal distortions in optics for high-power lasers. Our early work focused on adaptive optics for beam control in laser isotope separation and ground-based free electron lasers. We are currently developing innovative adaptive optics and laser systems for sodium laser guide star applications at the University of California`s Lick and Keck Observeratories. This talk will describe our adaptive optics technology and some of its applications in high-resolution imaging and beam control.

  2. Optical Design for Extremely Large Telescope Adaptive Optics Systems

    Energy Technology Data Exchange (ETDEWEB)

    Bauman, B J

    2003-11-26

    Designing an adaptive optics (AO) system for extremely large telescopes (ELT's) will present new optical engineering challenges. Several of these challenges are addressed in this work, including first-order design of multi-conjugate adaptive optics (MCAO) systems, pyramid wavefront sensors (PWFS's), and laser guide star (LGS) spot elongation. MCAO systems need to be designed in consideration of various constraints, including deformable mirror size and correction height. The y,{bar y} method of first-order optical design is a graphical technique that uses a plot with marginal and chief ray heights as coordinates; the optical system is represented as a segmented line. This method is shown to be a powerful tool in designing MCAO systems. From these analyses, important conclusions about configurations are derived. PWFS's, which offer an alternative to Shack-Hartmann (SH) wavefront sensors (WFS's), are envisioned as the workhorse of layer-oriented adaptive optics. Current approaches use a 4-faceted glass pyramid to create a WFS analogous to a quad-cell SH WFS. PWFS's and SH WFS's are compared and some newly-considered similarities and PWFS advantages are presented. Techniques to extend PWFS's are offered: First, PWFS's can be extended to more pixels in the image by tiling pyramids contiguously. Second, pyramids, which are difficult to manufacture, can be replaced by less expensive lenslet arrays. An approach is outlined to convert existing SH WFS's to PWFS's for easy evaluation of PWFS's. Also, a demonstration of PWFS's in sensing varying amounts of an aberration is presented. For ELT's, the finite altitude and finite thickness of LGS's means that the LGS will appear elongated from the viewpoint of subapertures not directly under the telescope. Two techniques for dealing with LGS spot elongation in SH WFS's are presented. One method assumes that the laser will be pulsed and uses a segmented micro

  3. Extreme Adaptive Optics Planet Imager: XAOPI

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B A; Graham, J; Poyneer, L; Sommargren, G; Wilhelmsen, J; Gavel, D; Jones, S; Kalas, P; Lloyd, J; Makidon, R; Olivier, S; Palmer, D; Patience, J; Perrin, M; Severson, S; Sheinis, A; Sivaramakrishnan, A; Troy, M; Wallace, K

    2003-09-17

    Ground based adaptive optics is a potentially powerful technique for direct imaging detection of extrasolar planets. Turbulence in the Earth's atmosphere imposes some fundamental limits, but the large size of ground-based telescopes compared to spacecraft can work to mitigate this. We are carrying out a design study for a dedicated ultra-high-contrast system, the eXtreme Adaptive Optics Planet Imager (XAOPI), which could be deployed on an 8-10m telescope in 2007. With a 4096-actuator MEMS deformable mirror it should achieve Strehl >0.9 in the near-IR. Using an innovative spatially filtered wavefront sensor, the system will be optimized to control scattered light over a large radius and suppress artifacts caused by static errors. We predict that it will achieve contrast levels of 10{sup 7}-10{sup 8} at angular separations of 0.2-0.8 inches around a large sample of stars (R<7-10), sufficient to detect Jupiter-like planets through their near-IR emission over a wide range of ages and masses. We are constructing a high-contrast AO testbed to verify key concepts of our system, and present preliminary results here, showing an RMS wavefront error of <1.3 nm with a flat mirror.

  4. Optical design of the adaptive optics laser guide star system

    Energy Technology Data Exchange (ETDEWEB)

    Bissinger, H. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The design of an adaptive optics package for the 3 meter Lick telescope is presented. This instrument package includes a 69 actuator deformable mirror and a Hartmann type wavefront sensor operating in the visible wavelength; a quadrant detector for the tip-tile sensor and a tip-tilt mirror to stabilize atmospheric first order tip-tile errors. A high speed computer drives the deformable mirror to achieve near diffraction limited imagery. The different optical components and their individual design constraints are described. motorized stages and diagnostics tools are used to operate and maintain alignment throughout observation time from a remote control room. The expected performance are summarized and actual results of astronomical sources are presented.

  5. Manufacturing of the ESO adaptive optics facility

    Science.gov (United States)

    Arsenault, R.,; Madec, P.-Y.; Hubin, N.; Stroebele, S.; Paufique, J.; Vernet, E.; Hackenberg, W.; Pirard, J.-F.; Jochum, L.; Glindemann, A.; Jost, A.; Conzelmann, R.; Kiekebusch, M.; Tordo, S.; Lizon, J.-L.; Donaldson, R.; Fedrigo, E.; Soenke, C.; Duchateau, M.; Bruton, A.; Delabre, B.; Downing, M.; Reyes, J.; Kolb, J.; Bechet, C.; Lelouarn, M.; Bonaccini Calia, D.; Quattri, M.; Guidolin, I.; Buzzoni, B.; Dupuy, C.; Guzman, R.; Comin, M.; Silber, A.; Quentin, J.; La Penna, P.; Manescau, A.; Jolley, P.; Heinz, V.; Duhoux, P.; Argomedo, J.; Gallieni, D.; Lazzarini, P.; Biasi, R.; Andrighettoni, M.; Angerer, G.; Pescoller, D.; Stuik, R.,; Deep, A.

    2010-07-01

    The ESO Adaptive Optics Facility (AOF) consists in an evolution of one of the ESO VLT unit telescopes to a laser driven adaptive telescope with a deformable mirror in its optical train, in this case the secondary 1.1m mirror, and four Laser Guide Stars (LGSs). This evolution implements many challenging technologies like the Deformable Secondary Mirror (DSM) including a thin shell mirror (1.1 m diameter and 2mm thin), the high power Na lasers (20W), the low Read-Out Noise (RON) WaveFront Sensor (WFS) camera (< 1e-) and SPARTA the new generation of Real Time Computers (RTC) for adaptive control. It also faces many problematic similar to any Extremely Large Telescope (ELT) and as such, will validate many technologies and solutions needed for the European ELT (E-ELT) 42m telescope. The AOF will offer a very large (7 arcmin) Field Of View (FOV) GLAO correction in J, H and K bands (GRAAL+Hawk-I), a visible integral field spectrograph with a 1 arcmin GLAO corrected FOV (GALACSI-MUSE WFM) and finally a LTAO 7.5" FOV (GALACSI-MUSE NFM). Most systems of the AOF have completed final design and are in manufacturing phase. Specific activities are linked to the modification of the 8m telescope in order to accommodate the new DSM and the 4 LGS Units assembled on its Center-Piece. A one year test period in Europe is planned to test and validate all modes and their performance followed by a commissioning phase in Paranal scheduled for 2014.

  6. Object-oriented Matlab adaptive optics toolbox

    Science.gov (United States)

    Conan, R.; Correia, C.

    2014-08-01

    Object-Oriented Matlab Adaptive Optics (OOMAO) is a Matlab toolbox dedicated to Adaptive Optics (AO) systems. OOMAO is based on a small set of classes representing the source, atmosphere, telescope, wavefront sensor, Deformable Mirror (DM) and an imager of an AO system. This simple set of classes allows simulating Natural Guide Star (NGS) and Laser Guide Star (LGS) Single Conjugate AO (SCAO) and tomography AO systems on telescopes up to the size of the Extremely Large Telescopes (ELT). The discrete phase screens that make the atmosphere model can be of infinite size, useful for modeling system performance on large time scales. OOMAO comes with its own parametric influence function model to emulate different types of DMs. The cone effect, altitude thickness and intensity profile of LGSs are also reproduced. Both modal and zonal modeling approach are implemented. OOMAO has also an extensive library of theoretical expressions to evaluate the statistical properties of turbulence wavefronts. The main design characteristics of the OOMAO toolbox are object-oriented modularity, vectorized code and transparent parallel computing. OOMAO has been used to simulate and to design the Multi-Object AO prototype Raven at the Subaru telescope and the Laser Tomography AO system of the Giant Magellan Telescope. In this paper, a Laser Tomography AO system on an ELT is simulated with OOMAO. In the first part, we set-up the class parameters and we link the instantiated objects to create the source optical path. Then we build the tomographic reconstructor and write the script for the pseudo-open-loop controller.

  7. The Tesat transportable adaptive optical ground station

    Science.gov (United States)

    Saucke, Karen; Seiter, Christoph; Heine, Frank; Gregory, Mark; Tröndle, Daniel; Fischer, Edgar; Berkefeld, Thomas; Feriencik, Mikael; Feriencik, Marco; Richter, Ines; Meyer, Rolf

    2016-03-01

    Tesat together with Synopta have built a Transportable Adaptive Optical Ground Station (TAOGS) under contract of German Aerospace Center DLR for communication with the 1st and 2nd generation of Tesat's spaceborne Laser Communication Terminals (LCTs), which employ coherent homodyne optical communication with 1064 nm and binary phase shift keying (BPSK) modulation. The TAOGS is able to communicate with space segments on low earth orbit (LEO, high pointing and tracking dynamics, 5.625 Gbps), and with space segments on geostationary orbit (GEO, low pointing dynamics, up to 40,000 km distance, optical data rate of 2.8125 Gbps and user data rate of 1.8 Gbps). After an alignment and testing phase at the location of Izana, Tenerife, using the TDP1 LCT on geostationary Alphasat as counter terminal, the TAOGS is now fully functioning. Several up-links, down-links and bi-directional links have been performed. Experimental results of some of these links are presented. An outlook to further activities is given.

  8. The Coming of Age of Adaptive Optics

    Science.gov (United States)

    1995-10-01

    How Ground-Based Astronomers Beat the Atmosphere Adaptive Optics (AO) is the new ``wonder-weapon'' in ground-based astronomy. By means of advanced electro-optical devices at their telescopes, astronomers are now able to ``neutralize'' the image-smearing turbulence of the terrestrial atmosphere (seen by the unaided eye as the twinkling of stars) so that much sharper images can be obtained than before. In practice, this is done with computer-controlled, flexible mirrors which refocus the blurred images up to 100 times per second, i.e. at a rate that is faster than the changes in the atmospheric turbulence. This means that finer details in astronomical objects can be studied and also - because of the improved concentration of light in the telescope's focal plane - that fainter objects can be observed. At the moment, Adaptive Optics work best in the infrared part of spectrum, but at some later time it may also significantly improve observations at the shorter wavelengths of visible light. The many-sided aspects of this new technology and its impact on astronomical instrumentation was the subject of a recent AO conference [1] with over 150 participants from about 30 countries, presenting a total of more than 100 papers. The Introduction of AO Techniques into Astronomy The scope of this meeting was the design, fabrication and testing of AO systems, characterisation of the sources of atmospheric disturbance, modelling of compensation systems, individual components, astronomical AO results, non-astronomical applications, laser guide star systems, non-linear optical phase conjugation, performance evaluation, and other areas of this wide and complex field, in which front-line science and high technology come together in a new and powerful symbiosis. One of the specific goals of the meeting was to develop contacts between AO scientists and engineers in the western world and their colleagues in Russia and Asia. For the first time at a conference of this type, nine Russian

  9. Wavelet methods in multi-conjugate adaptive optics

    OpenAIRE

    Helin, T; Yudytskiy, M.

    2013-01-01

    The next generation ground-based telescopes rely heavily on adaptive optics for overcoming the limitation of atmospheric turbulence. In the future adaptive optics modalities, like multi-conjugate adaptive optics (MCAO), atmospheric tomography is the major mathematical and computational challenge. In this severely ill-posed problem a fast and stable reconstruction algorithm is needed that can take into account many real-life phenomena of telescope imaging. We introduce a novel reconstruction m...

  10. Receding-horizon adaptive contyrol of aero-optical wavefronts

    NARCIS (Netherlands)

    Tesch, J.; Gibson, S.; Verhaegen, M.

    2013-01-01

    A new method for adaptive prediction and correction of wavefront errors in adaptive optics (AO) is introduced. The new method is based on receding-horizon control design and an adaptive lattice filter. Experimental results presented illustrate the capability of the new adaptive controller to predict

  11. The Durham adaptive optics real-time controller

    CERN Document Server

    Basden, Alastair; Myers, Richard; Younger, Eddy

    2010-01-01

    The Durham adaptive optics real-time controller was initially a proof of concept design for a generic adaptive optics control system. It has since been developed into a modern and powerful CPU based real-time control system, capable of using hardware acceleration (including FPGAs and GPUs), based primarily around commercial off the shelf hardware. It is powerful enough to be used as the real-time controller for all currently planned 8~m class telescope adaptive optics systems. Here we give details of this controller and the concepts behind it, and report on performance including latency and jitter, which is less than 10~$\\mu$s for small adaptive optics systems.

  12. Adaptive optics optical coherence tomography at 1 MHz.

    Science.gov (United States)

    Kocaoglu, Omer P; Turner, Timothy L; Liu, Zhuolin; Miller, Donald T

    2014-12-01

    Image acquisition speed of optical coherence tomography (OCT) remains a fundamental barrier that limits its scientific and clinical utility. Here we demonstrate a novel multi-camera adaptive optics (AO-)OCT system for ophthalmologic use that operates at 1 million A-lines/s at a wavelength of 790 nm with 5.3 μm axial resolution in retinal tissue. Central to the spectral-domain design is a novel detection channel based on four high-speed spectrometers that receive light sequentially from a 1 × 4 optical switch assembly. Absence of moving parts enables ultra-fast (50ns) and precise switching with low insertion loss (-0.18 dB per channel). This manner of control makes use of all available light in the detection channel and avoids camera dead-time, both critical for imaging at high speeds. Additional benefit in signal-to-noise accrues from the larger numerical aperture afforded by the use of AO and yields retinal images of comparable dynamic range to that of clinical OCT. We validated system performance by a series of experiments that included imaging in both model and human eyes. We demonstrated the performance of our MHz AO-OCT system to capture detailed images of individual retinal nerve fiber bundles and cone photoreceptors. This is the fastest ophthalmic OCT system we know of in the 700 to 915 nm spectral band.

  13. Optical Design and Optimization of Translational Reflective Adaptive Optics Ophthalmoscopes

    Science.gov (United States)

    Sulai, Yusufu N. B.

    The retina serves as the primary detector for the biological camera that is the eye. It is composed of numerous classes of neurons and support cells that work together to capture and process an image formed by the eye's optics, which is then transmitted to the brain. Loss of sight due to retinal or neuro-ophthalmic disease can prove devastating to one's quality of life, and the ability to examine the retina in vivo is invaluable in the early detection and monitoring of such diseases. Adaptive optics (AO) ophthalmoscopy is a promising diagnostic tool in early stages of development, still facing significant challenges before it can become a clinical tool. The work in this thesis is a collection of projects with the overarching goal of broadening the scope and applicability of this technology. We begin by providing an optical design approach for AO ophthalmoscopes that reduces the aberrations that degrade the performance of the AO correction. Next, we demonstrate how to further improve image resolution through the use of amplitude pupil apodization and non-common path aberration correction. This is followed by the development of a viewfinder which provides a larger field of view for retinal navigation. Finally, we conclude with the development of an innovative non-confocal light detection scheme which improves the non-invasive visualization of retinal vasculature and reveals the cone photoreceptor inner segments in healthy and diseased eyes.

  14. Optically sensitive Medipix2 detector for adaptive optics wavefront sensing

    CERN Document Server

    Vallerga, John; Tremsina, Anton; Siegmund, Oswald; Mikulec, Bettina; Clark, Allan G; CERN. Geneva

    2005-01-01

    A new hybrid optical detector is described that has many of the attributes desired for the next generation adaptive optics (AO) wavefront sensors. The detector consists of a proximity focused microchannel plate (MCP) read out by multi-pixel application specific integrated circuit (ASIC) chips developed at CERN ("Medipix2") with individual pixels that amplify, discriminate and count input events. The detector has 256 x 256 pixels, zero readout noise (photon counting), can be read out at 1 kHz frame rates and is abutable on 3 sides. The Medipix2 readout chips can be electronically shuttered down to a temporal window of a few microseconds with an accuracy of 10 ns. When used in a Shack-Hartmann style wavefront sensor, a detector with 4 Medipix chips should be able to centroid approximately 5000 spots using 7 x 7 pixel sub-apertures resulting in very linear, off-null error correction terms. The quantum efficiency depends on the optical photocathode chosen for the bandpass of interest.

  15. Wavefront Control for Extreme Adaptive Optics

    Energy Technology Data Exchange (ETDEWEB)

    Poyneer, L A

    2003-07-16

    Current plans for Extreme Adaptive Optics systems place challenging requirements on wave-front control. This paper focuses on control system dynamics, wave-front sensing and wave-front correction device characteristics. It may be necessary to run an ExAO system after a slower, low-order AO system. Running two independent systems can result in very good temporal performance, provided specific design constraints are followed. The spatially-filtered wave-front sensor, which prevents aliasing and improves PSF sensitivity, is summarized. Different models of continuous and segmented deformable mirrors are studied. In a noise-free case, a piston-tip-tilt segmented MEMS device can achieve nearly equivalent performance to a continuous-sheet DM in compensating for a static phase aberration with use of spatial filtering.

  16. Phase retrieval techniques for adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Carrano, C. J., LLNL

    1998-03-01

    We have developed and tested a method for minimizing static aberrations in adaptive optics systems. In order to correct the static phase aberrations, we need to measure the aberrations through the entire system. We have employed various phase retrieval algorithms to detect these aberrations. We have performed simulations of our experimental setup demonstrating that phase retrieval can improve the static aberrations to below the 20 nm rms level, with the limiting factor being local turbulence in the A0 system. Experimentally thus far, we have improved the static aberrations down to the 50 nm level, with the limiting factor being the ability to adjust the deformable mirror. This should be improved with better control algorithms now being implemented.

  17. Durham adaptive optics real-time controller.

    Science.gov (United States)

    Basden, Alastair; Geng, Deli; Myers, Richard; Younger, Eddy

    2010-11-10

    The Durham adaptive optics (AO) real-time controller was initially a proof of concept design for a generic AO control system. It has since been developed into a modern and powerful central-processing-unit-based real-time control system, capable of using hardware acceleration (including field programmable gate arrays and graphical processing units), based primarily around commercial off-the-shelf hardware. It is powerful enough to be used as the real-time controller for all currently planned 8 m class telescope AO systems. Here we give details of this controller and the concepts behind it, and report on performance, including latency and jitter, which is less than 10 μs for small AO systems.

  18. Design and performance optimization of fiber optic adaptive filters.

    Science.gov (United States)

    Paparao, P; Ghosh, A; Allen, S D

    1991-05-10

    There is a great need for easy-to-fabricate and versatile fiber optic signal processing systems in which optical fibers are used for the delay and storage of wideband guided lightwave signals. We describe the design of the least-mean-square algorithm-based fiber optic adaptive filters for processing guided lightwave signals in real time. Fiber optic adaptive filters can learn to change their parameters or to process a set of characteristics of the input signal. In our realization we employ as few electronic devices as possible and use optical computation to utilize the advantages of optics in the processing speed, parallelism, and interconnection. Many schemes for optical adaptive filtering of electronic signals are available in the literature. The new optical adaptive filters described in this paper are for optical processing of guided lightwave signals, not electronic signals. We analyzed the convergence or learning characteristics of the adaptive filtering process as a function of the filter parameters and the fiber optic hardware errors. From this analysis we found that the effects of the optical round-off errors and noise can be reduced, and the learning speed can be comparatively increased in our design through an optimal selection of the filter parameters. A general knowledge of the fiber optic hardware, the statistics of the lightwave signal, and the desired goal of the adaptive processing are enough for this optimum selection of the parameters. Detailed computer simulations validate the theoretical results of performance optimization.

  19. Proposed Multiconjugate Adaptive Optics Experiment at Lick Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Bauman, B J; Gavel, D T; Flath, L M; Hurd, R L; Max, C E; Olivier, S S

    2001-08-15

    While the theory behind design of multiconjugate adaptive optics (MCAO) systems is growing, there is still a paucity of experience building and testing such instruments. We propose using the Lick adaptive optics (AO) system as a basis for demonstrating the feasibility/workability of MCAO systems, testing underlying assumptions, and experimenting with different approaches to solving MCAO system issues.

  20. Linear zonal atmospheric prediction for adaptive optics

    Science.gov (United States)

    McGuire, Patrick C.; Rhoadarmer, Troy A.; Coy, Hanna A.; Angel, J. Roger P.; Lloyd-Hart, Michael

    2000-07-01

    We compare linear zonal predictors of atmospheric turbulence for adaptive optics. Zonal prediction has the possible advantage of being able to interpret and utilize wind-velocity information from the wavefront sensor better than modal prediction. For simulated open-loop atmospheric data for a 2- meter 16-subaperture AO telescope with 5 millisecond prediction and a lookback of 4 slope-vectors, we find that Widrow-Hoff Delta-Rule training of linear nets and Back- Propagation training of non-linear multilayer neural networks is quite slow, getting stuck on plateaus or in local minima. Recursive Least Squares training of linear predictors is two orders of magnitude faster and it also converges to the solution with global minimum error. We have successfully implemented Amari's Adaptive Natural Gradient Learning (ANGL) technique for a linear zonal predictor, which premultiplies the Delta-Rule gradients with a matrix that orthogonalizes the parameter space and speeds up the training by two orders of magnitude, like the Recursive Least Squares predictor. This shows that the simple Widrow-Hoff Delta-Rule's slow convergence is not a fluke. In the case of bright guidestars, the ANGL, RLS, and standard matrix-inversion least-squares (MILS) algorithms all converge to the same global minimum linear total phase error (approximately 0.18 rad2), which is only approximately 5% higher than the spatial phase error (approximately 0.17 rad2), and is approximately 33% lower than the total 'naive' phase error without prediction (approximately 0.27 rad2). ANGL can, in principle, also be extended to make non-linear neural network training feasible for these large networks, with the potential to lower the predictor error below the linear predictor error. We will soon scale our linear work to the approximately 108-subaperture MMT AO system, both with simulations and real wavefront sensor data from prime focus.

  1. Adaptive optics and phase diversity imaging for responsive space applications.

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Mark William; Wick, David Victor

    2004-11-01

    The combination of phase diversity and adaptive optics offers great flexibility. Phase diverse images can be used to diagnose aberrations and then provide feedback control to the optics to correct the aberrations. Alternatively, phase diversity can be used to partially compensate for aberrations during post-detection image processing. The adaptive optic can produce simple defocus or more complex types of phase diversity. This report presents an analysis, based on numerical simulations, of the efficiency of different modes of phase diversity with respect to compensating for specific aberrations during post-processing. It also comments on the efficiency of post-processing versus direct aberration correction. The construction of a bench top optical system that uses a membrane mirror as an active optic is described. The results of characterization tests performed on the bench top optical system are presented. The work described in this report was conducted to explore the use of adaptive optics and phase diversity imaging for responsive space applications.

  2. Turbulence profiling for adaptive optics tomographic reconstructors

    Science.gov (United States)

    Laidlaw, Douglas J.; Osborn, James; Wilson, Richard W.; Morris, Timothy J.; Butterley, Timothy; Reeves, Andrew P.; Townson, Matthew J.; Gendron, Éric; Vidal, Fabrice; Morel, Carine

    2016-07-01

    To approach optimal performance advanced Adaptive Optics (AO) systems deployed on ground-based telescopes must have accurate knowledge of atmospheric turbulence as a function of altitude. Stereo-SCIDAR is a high-resolution stereoscopic instrument dedicated to this measure. Here, its profiles are directly compared to internal AO telemetry atmospheric profiling techniques for CANARY (Vidal et al. 20141), a Multi-Object AO (MOAO) pathfinder on the William Herschel Telescope (WHT), La Palma. In total twenty datasets are analysed across July and October of 2014. Levenberg-Marquardt fitting algorithms dubbed Direct Fitting and Learn 2 Step (L2S; Martin 20142) are used in the recovery of profile information via covariance matrices - respectively attaining average Pearson product-moment correlation coefficients with stereo-SCIDAR of 0.2 and 0.74. By excluding the measure of covariance between orthogonal Wavefront Sensor (WFS) slopes these results have revised values of 0.65 and 0.2. A data analysis technique that combines L2S and SLODAR is subsequently introduced that achieves a correlation coefficient of 0.76.

  3. Adaptive optics for laser space debris removal

    Science.gov (United States)

    Bennet, Francis; Conan, Rodolphe; D'Orgeville, Celine; Dawson, Murray; Paulin, Nicolas; Price, Ian; Rigaut, Francois; Ritchie, Ian; Smith, Craig; Uhlendorf, Kristina

    2012-07-01

    Space debris in low Earth orbit below 1500km is becoming an increasing threat to satellites and spacecrafts. Radar and laser tracking are currently used to monitor the orbits of thousands of space debris and active satellites are able to use this information to manoeuvre out of the way of a predicted collision. However, many satellites are not able to manoeuvre and debris-on debris collisions are becoming a signicant contributor to the growing space debris population. The removal of the space debris from orbit is the preferred and more denitive solution. Space debris removal may be achieved through laser ablation, whereby a high power laser corrected with an adaptive optics system could, in theory, allow ablation of the debris surface and so impart a remote thrust on the targeted object. The goal of this is to avoid collisions between space debris to prevent an exponential increase in the number of space debris objects. We are developing an experiment to demonstrate the feasibility of laser ablation for space debris removal. This laser ablation demonstrator utilises a pulsed sodium laser to probe the atmosphere ahead of the space debris and the sun re ection of the space debris is used to provide atmospheric tip{tilt information. A deformable mirror is then shaped to correct an infrared laser beam on the uplink path to the debris. We present here the design and the expected performance of the system.

  4. KAPAO: A Pomona College Adaptive Optics Instrument

    Science.gov (United States)

    Choi, Philip I.; Severson, S. A.; Rudy, A. R.; Gilbreth, B. N.; Contreras, D. S.; McGonigle, L. P.; Chin, R. M.; Horn, B.; Hoidn, O.; Spjut, E.; Baranec, C.; Riddle, R.

    2011-01-01

    We describe our project (KAPAO) to develop and deploy a low-cost, remote-access, natural guide star adaptive optics system for the Pomona College Table Mountain Observatory (TMO) 1-meter telescope. The system will offer simultaneous dual-band, diffraction-limited imaging at visible and near-infrared wavelengths and will deliver an order-of-magnitude improvement in point source sensitivity and angular resolution relative to the current TMO seeing limits. In order to ensure reliability, minimize costs and encourage replication efforts, off-the-shelf components that include a MEMS deformable mirror, a Shack-Hartmann wavefront sensor and a piezo-electric tip-tilt mirror are being adopted for the core hardware elements. We present: the instrument design; performance predictions based on AO simulations; and the current status of the testbed instrument and high-speed control system. Beyond the expanded scientific capabilities enabled by AO-enhanced resolution and sensitivity, the interdisciplinary nature of the instrument development effort provides an exceptional opportunity to train a broad range of undergraduate STEM students in AO technologies and techniques. The breadth of our collaboration, which includes both public (Sonoma State University) and private (Pomona and Harvey Mudd Colleges) undergraduate institutions has enabled us to engage students ranging from physics, astronomy, engineering and computer science in the early stages of this project. This material is based upon work supported by the National Science Foundation under Grant No. 0960343.

  5. Stellar photometry with Multi Conjugate Adaptive Optics

    CERN Document Server

    Fiorentino, Giuliana; McConnachie, Alan; Stetson, Peter B; Bono, Giuseppe; Turri, Paolo; Andersen, David; Veran, Jean-Pierre; Diolaiti, Emiliano; Schreiber, Laura; Ciliegi, Paolo; Bellazzini, Michele; Tolstoy, Eline; Monelli, Matteo; Iannicola, Giacinto; Ferraro, Ivan; Testa, Vincenzo

    2016-01-01

    We overview the current status of photometric analyses of images collected with Multi Conjugate Adaptive Optics (MCAO) at 8-10m class telescopes that operated, or are operating, on sky. Particular attention will be payed to resolved stellar population studies. Stars in crowded stellar systems, such as globular clusters or in nearby galaxies, are ideal test particles to test AO performance. We will focus the discussion on photometric precision and accuracy reached nowadays. We briefly describe our project on stellar photometry and astrometry of Galactic globular clusters using images taken with GeMS at the Gemini South telescope. We also present the photometry performed with DAOPHOT suite of programs into the crowded regions of these globulars reaching very faint limiting magnitudes Ks ~21.5 mag on moderately large fields of view (~1.5 arcmin squared). We highlight the need for new algorithms to improve the modeling of the complex variation of the Point Spread Function across the ?eld of view. Finally, we outl...

  6. Recent advances in astronomical adaptive optics.

    Science.gov (United States)

    Hart, Michael

    2010-06-01

    The imaging performance of large ground-based astronomical telescopes is compromised by dynamic wavefront aberration caused by atmospheric turbulence. Techniques to measure and correct the aberration in real time, collectively called adaptive optics (AO), have been developed over the past half century, but it is only within the past decade that the delivery of diffraction-limited image quality at near- and mid-infrared wavelengths at many of the world's biggest telescopes has become routine. Exploitation of this new capability has led to a number of ground-breaking astronomical results, which has in turn spurred the continued development of AO to address ever more technical challenges that limit its scientific applicability. I review the present state of the art, highlight a number of noteworthy scientific results, and outline several ongoing experiments designed to broaden the scope of observations that can be undertaken with AO. In particular, I explore the significant advances required in AO technology to satisfy the needs for a new generation of extremely large telescopes of diameter 25 m and larger that are now being designed.

  7. Large Binocular Telescope Adaptive Optics System: New achievements and perspectives in adaptive optics

    CERN Document Server

    Esposito, Simone; Pinna, Enrico; Puglisi, Alfio; Quirós-Pacheco, Fernando; Arcidiacono, Carmelo; Xompero, Marco; Briguglio, Runa; Agapito, Guido; Busoni, Lorenzo; Fini, Luca; Argomedo, Javier; Gherardi, Alessandro; Brusa, Guido; Miller, Douglas; Guerra, Juan Carlos; Stefanini, Paolo; Salinari, Piero; 10.1117/12.898641

    2012-01-01

    The Large Binocular Telescope (LBT) is a unique telescope featuring two co-mounted optical trains with 8.4m primary mirrors. The telescope Adaptive Optics (AO) system uses two innovative key components, namely an adaptive secondary mirror with 672 actuators and a high-order pyramid wave-front sensor. During the on-sky commissioning such a system reached performances never achieved before on large ground-based optical telescopes. Images with 40mas resolution and Strehl Ratios higher than 80% have been acquired in H band (1.6 micron). Such images showed a contrast as high as 10e-4. Based on these results, we compare the performances offered by a Natural Guide Star (NGS) system upgraded with the state-of-the-art technology and those delivered by existing Laser Guide Star (LGS) systems. The comparison, in terms of sky coverage and performances, suggests rethinking the current role ascribed to NGS and LGS in the next generation of AO systems for the 8-10 meter class telescopes and Extremely Large Telescopes (ELTs)...

  8. Adaptive optics parallel near-confocal scanning ophthalmoscopy.

    Science.gov (United States)

    Lu, Jing; Gu, Boyu; Wang, Xiaolin; Zhang, Yuhua

    2016-08-15

    We present an adaptive optics parallel near-confocal scanning ophthalmoscope (AOPCSO) using a digital micromirror device (DMD). The imaging light is modulated to be a line of point sources by the DMD, illuminating the retina simultaneously. By using a high-speed line camera to acquire the image and using adaptive optics to compensate the ocular wave aberration, the AOPCSO can image the living human eye with cellular level resolution at the frame rate of 100 Hz. AOPCSO has been demonstrated with improved spatial resolution in imaging of the living human retina compared with adaptive optics line scan ophthalmoscopy.

  9. Simulating Astronomical Adaptive Optics Systems Using Yao

    Science.gov (United States)

    Rigaut, François; Van Dam, Marcos

    2013-12-01

    Adaptive Optics systems are at the heart of the coming Extremely Large Telescopes generation. Given the importance, complexity and required advances of these systems, being able to simulate them faithfully is key to their success, and thus to the success of the ELTs. The type of systems envisioned to be built for the ELTs cover most of the AO breeds, from NGS AO to multiple guide star Ground Layer, Laser Tomography and Multi-Conjugate AO systems, with typically a few thousand actuators. This represents a large step up from the current generation of AO systems, and accordingly a challenge for existing AO simulation packages. This is especially true as, in the past years, computer power has not been following Moore's law in its most common understanding; CPU clocks are hovering at about 3GHz. Although the use of super computers is a possible solution to run these simulations, being able to use smaller machines has obvious advantages: cost, access, environmental issues. By using optimised code in an already proven AO simulation platform, we were able to run complex ELT AO simulations on very modest machines, including laptops. The platform is YAO. In this paper, we describe YAO, its architecture, its capabilities, the ELT-specific challenges and optimisations, and finally its performance. As an example, execution speed ranges from 5 iterations per second for a 6 LGS 60x60 subapertures Shack-Hartmann Wavefront sensor Laser Tomography AO system (including full physical image formation and detector characteristics) up to over 30 iterations/s for a single NGS AO system.

  10. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

    Science.gov (United States)

    Cua, Michelle; Wahl, Daniel J.; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J.; Jian, Yifan; Sarunic, Marinko V.

    2016-09-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems.

  11. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging.

    Science.gov (United States)

    Cua, Michelle; Wahl, Daniel J; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J; Jian, Yifan; Sarunic, Marinko V

    2016-09-07

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems.

  12. Piezoelectric deformable mirror for intra-cavity laser adaptive optics.

    CSIR Research Space (South Africa)

    Long, CS

    2008-03-01

    Full Text Available This paper describes the development of a deformable mirror to be used in conjunction with diffractive optical elements inside a laser cavity. A prototype piezoelectric unimorph adaptive mirror was developed to correct for time dependent phase...

  13. Solar adaptive optics: specificities, lessons learned, and open alternatives

    Science.gov (United States)

    Montilla, I.; Marino, J.; Asensio Ramos, A.; Collados, M.; Montoya, L.; Tallon, M.

    2016-07-01

    First on sky adaptive optics experiments were performed on the Dunn Solar Telescope on 1979, with a shearing interferometer and limited success. Those early solar adaptive optics efforts forced to custom-develop many components, such as Deformable Mirrors and WaveFront Sensors, which were not available at that time. Later on, the development of the correlation Shack-Hartmann marked a breakthrough in solar adaptive optics. Since then, successful Single Conjugate Adaptive Optics instruments have been developed for many solar telescopes, i.e. the National Solar Observatory, the Vacuum Tower Telescope and the Swedish Solar Telescope. Success with the Multi Conjugate Adaptive Optics systems for GREGOR and the New Solar Telescope has proved to be more difficult to attain. Such systems have a complexity not only related to the number of degrees of freedom, but also related to the specificities of the Sun, used as reference, and the sensing method. The wavefront sensing is performed using correlations on images with a field of view of 10", averaging wavefront information from different sky directions, affecting the sensing and sampling of high altitude turbulence. Also due to the low elevation at which solar observations are performed we have to include generalized fitting error and anisoplanatism, as described by Ragazzoni and Rigaut, as non-negligible error sources in the Multi Conjugate Adaptive Optics error budget. For the development of the next generation Multi Conjugate Adaptive Optics systems for the Daniel K. Inouye Solar Telescope and the European Solar Telescope we still need to study and understand these issues, to predict realistically the quality of the achievable reconstruction. To improve their designs other open issues have to be assessed, i.e. possible alternative sensing methods to avoid the intrinsic anisoplanatism of the wide field correlation Shack-Hartmann, new parameters to estimate the performance of an adaptive optics solar system, alternatives to

  14. Astronomy applications of adaptive optics at Lawrence Livermore National Laboratory

    Science.gov (United States)

    Bauman, Brian J.; Gavel, Donald T.

    2003-06-01

    Astronomical applications of adaptive optics at Lawrence Livermore National Laboratory (LLNL) has a history that extends from 1984. The program started with the Lick Observatory Adaptive Optics system and has progressed through the years to lever-larger telescopes: Keck, and now the proposed CELT (California Extremely Large Telescope) 30m telescope. LLNL AO continues to be at the forefront of AO development and science.

  15. Laser guide star adaptive optics: Present and future

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, S.S.; Max, C.E.

    1993-03-01

    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.

  16. Astronomy Applications of Adaptive Optics at Lawrence Livermore National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Bauman, B J; Gavel, D T

    2003-04-23

    Astronomical applications of adaptive optics at Lawrence Livermore National Laboratory (LLNL) has a history that extends from 1984. The program started with the Lick Observatory Adaptive Optics system and has progressed through the years to lever-larger telescopes: Keck, and now the proposed CELT (California Extremely Large Telescope) 30m telescope. LLNL AO continues to be at the forefront of AO development and science.

  17. How adaptive optics may have won the Cold War

    Science.gov (United States)

    Tyson, Robert K.

    2013-05-01

    While there are many theories and studies concerning the end of the Cold War, circa 1990, I postulate that one of the contributors to the result was the development of adaptive optics. The emergence of directed energy weapons, specifically space-based and ground-based high energy lasers made practicable with adaptive optics, showed that a successful defense against inter-continental ballistic missiles was not only possible, but achievable in a reasonable period of time.

  18. Adaptive optics in digital micromirror based confocal microscopy

    Science.gov (United States)

    Pozzi, P.; Wilding, D.; Soloviev, O.; Vdovin, G.; Verhaegen, M.

    2016-03-01

    This proceeding reports early results in the development of a new technique for adaptive optics in confocal microscopy. The term adaptive optics refers to the branch of optics in which an active element in the optical system is used to correct inhomogeneities in the media through which light propagates. In its most classical form, mostly used in astronomical imaging, adaptive optics is achieved through a closed loop in which the actuators of a deformable mirror are driven by a wavefront sensor. This approach is severely limited in fluorescence microscopy, as the use of a wavefront sensor requires the presence of a bright, point like source in the field of view, a condition rarely satisfied in microscopy samples. Previously reported approaches to adaptive optics in fluorescence microscopy are therefore limited to the inclusion of fluorescent microspheres in the sample, to use as bright stars for wavefront sensors, or time consuming sensorless optimization procedures, requiring several seconds of optimization before the acquisition of a single image. We propose an alternative approach to the problem, implementing sensorless adaptive optics in a Programmable array microscope. A programmable array microscope is a microscope based on a digital micromirror device, in which the single elements of the micromirror act both as point sources and pinholes.

  19. Optimization-based wavefront sensorless adaptive optics for multiphoton microscopy

    NARCIS (Netherlands)

    Antonello, J.; Werkhoven, T. van; Verhaegen, M.; Truong, H.H.; Keller, C.U.; Gerritsen, H.C.

    2014-01-01

    Optical aberrations have detrimental effects in multiphoton microscopy. These effects can be curtailed by implementing model-based wavefront sensorless adaptive optics, which only requires the addition of a wavefront shaping device, such as a deformable mirror (DM) to an existing microscope. The abe

  20. Photonic crystal-adaptive optical devices

    DEFF Research Database (Denmark)

    Buss, Thomas

    -doped liquid crystal gain medium for the realization of cheap and compact optically pumped, electrically tunable lasers. Finally, a transparent projection display is presented which uses sub-wavelength gratings for redirection of light guided inside a waveguide and facilitates electro-optic switching by means...

  1. Micro-opto-electro-mechanical (MOEM) adaptive optic system

    Science.gov (United States)

    Clark, Rodney L.; Karpinisky, John R.; Hammer, Jay A.; Anderson, Roland B.; Lindsey, Randall L.; Brown, Daniel M.; Merritt, Paul H.

    1997-04-01

    This paper discusses the application of MOEM technology to adaptive optics. An experiment is described in which a micromachined mirror array is used in a closed loop adaptive optic demonstration. An interferometer wavefront sensor is used for wavefront sensing. Parallel analog electronics are used for the wavefront reconstruction. Parallel operational amplifiers are used to drive the micromirrors. The actuators utilize a novel silicon design developed by SY Technology, Inc. The actuators have a measured frequency response of 15kHz, and a maximum usable stroke of 4 microns. The entire adaptive optic demonstration has a bandwidth exceeding 10kHz. Measured performance is described. The experiments conducted are designed to explore the feasibility of creating a single chip adaptive optic system, also described in this paper. This chip would combine all on a single VLSI chip aspects of a complete adaptive optics system, wavefront sensing, wavefront reconstruction, and wavefront correction. The wavefront sensing would be accomplished with a novel compact shearing interferometer design. The analog refractive and diffractive micro optics will be fabricated using a new single step analog mask technology. The reconstruction circuit would use an analog resistive grid solver. The resistive grid would be fabricated in polysilicon. The drive circuits and micromirror actuators would use standard CMOS silicon fabrication methods.

  2. A dual-modal retinal imaging system with adaptive optics.

    Science.gov (United States)

    Meadway, Alexander; Girkin, Christopher A; Zhang, Yuhua

    2013-12-02

    An adaptive optics scanning laser ophthalmoscope (AO-SLO) is adapted to provide optical coherence tomography (OCT) imaging. The AO-SLO function is unchanged. The system uses the same light source, scanning optics, and adaptive optics in both imaging modes. The result is a dual-modal system that can acquire retinal images in both en face and cross-section planes at the single cell level. A new spectral shaping method is developed to reduce the large sidelobes in the coherence profile of the OCT imaging when a non-ideal source is used with a minimal introduction of noise. The technique uses a combination of two existing digital techniques. The thickness and position of the traditionally named inner segment/outer segment junction are measured from individual photoreceptors. In-vivo images of healthy and diseased human retinas are demonstrated.

  3. Bayesian adaptive survey protocols for resource management

    Science.gov (United States)

    Halstead, Brian J.; Wylie, Glenn D.; Coates, Peter S.; Casazza, Michael L.

    2011-01-01

    Transparency in resource management decisions requires a proper accounting of uncertainty at multiple stages of the decision-making process. As information becomes available, periodic review and updating of resource management protocols reduces uncertainty and improves management decisions. One of the most basic steps to mitigating anthropogenic effects on populations is determining if a population of a species occurs in an area that will be affected by human activity. Species are rarely detected with certainty, however, and falsely declaring a species absent can cause improper conservation decisions or even extirpation of populations. We propose a method to design survey protocols for imperfectly detected species that accounts for multiple sources of uncertainty in the detection process, is capable of quantitatively incorporating expert opinion into the decision-making process, allows periodic updates to the protocol, and permits resource managers to weigh the severity of consequences if the species is falsely declared absent. We developed our method using the giant gartersnake (Thamnophis gigas), a threatened species precinctive to the Central Valley of California, as a case study. Survey date was negatively related to the probability of detecting the giant gartersnake, and water temperature was positively related to the probability of detecting the giant gartersnake at a sampled location. Reporting sampling effort, timing and duration of surveys, and water temperatures would allow resource managers to evaluate the probability that the giant gartersnake occurs at sampled sites where it is not detected. This information would also allow periodic updates and quantitative evaluation of changes to the giant gartersnake survey protocol. Because it naturally allows multiple sources of information and is predicated upon the idea of updating information, Bayesian analysis is well-suited to solving the problem of developing efficient sampling protocols for species of

  4. PASSATA - Object oriented numerical simulation software for adaptive optics

    CERN Document Server

    Agapito, G; Esposito, S

    2016-01-01

    We present the last version of the PyrAmid Simulator Software for Adaptive opTics Arcetri (PASSATA), an IDL and CUDA based object oriented software developed in the Adaptive Optics group of the Arcetri observatory for Monte-Carlo end-to-end adaptive optics simulations. The original aim of this software was to evaluate the performance of a single conjugate adaptive optics system for ground based telescope with a pyramid wavefront sensor. After some years of development, the current version of PASSATA is able to simulate several adaptive optics systems: single conjugate, multi conjugate and ground layer, with Shack Hartmann and Pyramid wavefront sensors. It can simulate from 8m to 40m class telescopes, with diffraction limited and resolved sources at finite or infinite distance from the pupil. The main advantages of this software are the versatility given by the object oriented approach and the speed given by the CUDA implementation of the most computational demanding routines. We describe the software with its...

  5. PASSATA: object oriented numerical simulation software for adaptive optics

    Science.gov (United States)

    Agapito, G.; Puglisi, A.; Esposito, S.

    2016-07-01

    We present the last version of the PyrAmid Simulator Software for Adaptive opTics Arcetri (PASSATA), an IDL and CUDA based object oriented software developed in the Adaptive Optics group of the Arcetri observatory for Monte-Carlo end-to-end adaptive optics simulations. The original aim of this software was to evaluate the performance of a single conjugate adaptive optics system for ground based telescope with a pyramid wavefront sensor. After some years of development, the current version of PASSATA is able to simulate several adaptive optics systems: single conjugate, multi conjugate and ground layer, with Shack Hartmann and Pyramid wavefront sensors. It can simulate from 8m to 40m class telescopes, with diffraction limited and resolved sources at finite or infinite distance from the pupil. The main advantages of this software are the versatility given by the object oriented approach and the speed given by the CUDA implementation of the most computational demanding routines. We describe the software with its last developments and present some examples of application.

  6. The VLT Adaptive Optics Facility Project: Telescope Systems

    Science.gov (United States)

    Arsenault, Robin; Hubin, Norbert; Stroebele, Stefan; Fedrigo, Enrico; Oberti, Sylvain; Kissler-Patig, Markus; Bacon, Roland; McDermid, Richard; Bonaccini-Calia, Domenico; Biasi, Roberto; Gallieni, Daniele; Riccardi, Armando; Donaldson, Rob; Lelouarn, Miska; Hackenberg, Wolfgang; Conzelman, Ralf; Delabre, Bernard; Stuik, Remko; Paufique, Jerome; Kasper, Markus; Vernet, Elise; Downing, Mark; Esposito, Simone; Duchateau, Michel; Franx, Marijn; Myers, Richard; Goodsell, Steven

    2006-03-01

    The Adaptive Optics Facility is a project to convert UT4 into a specialised Adaptive Telescope. The present secondary mirror (M2) will be replaced by a new M2-Unit hosting a 1170-actuator deformable mirror. The three focal stations will be equipped with instruments adapted to the new capability of this UT. Two instruments have been identified for the two Nasmyth foci: Hawk-I with its AO module GRAAL allowing a Ground Layer Adaptive Optics correction and MUSE with GALACSI for GLAO correction and Laser Tomography Adaptive Optics correction. A future instrument still needs to be defined for the Cassegrain focus. Several guide stars are required for the type of adaptive corrections needed and a Four Laser Guide Star Facility (4LGSF) is being developed in the scope of the AO Facility. Convex mirrors like the VLT M2 represent a major challenge for testing and a substantial effort is dedicated to this. ASSIST, is a test bench that will allow testing of the Deformable Secondary Mirror and both instruments with simulated turbulence. This article focusses on the telescope systems (Adaptive Secondary, Four Laser Guide Star Facility, RTC platform and ASSIST Test Bench). The following article describes the AO Modules GALACSI and GRAAL.

  7. Accuracy requirements of optical linear algebra processors in adaptive optics imaging systems

    Science.gov (United States)

    Downie, John D.

    1990-01-01

    A ground-based adaptive optics imaging telescope system attempts to improve image quality by detecting and correcting for atmospherically induced wavefront aberrations. The required control computations during each cycle will take a finite amount of time. Longer time delays result in larger values of residual wavefront error variance since the atmosphere continues to change during that time. Thus an optical processor may be well-suited for this task. This paper presents a study of the accuracy requirements in a general optical processor that will make it competitive with, or superior to, a conventional digital computer for the adaptive optics application. An optimization of the adaptive optics correction algorithm with respect to an optical processor's degree of accuracy is also briefly discussed.

  8. Accuracy requirements of optical linear algebra processors in adaptive optics imaging systems

    Science.gov (United States)

    Downie, John D.

    1990-01-01

    A ground-based adaptive optics imaging telescope system attempts to improve image quality by detecting and correcting for atmospherically induced wavefront aberrations. The required control computations during each cycle will take a finite amount of time. Longer time delays result in larger values of residual wavefront error variance since the atmosphere continues to change during that time. Thus an optical processor may be well-suited for this task. This paper presents a study of the accuracy requirements in a general optical processor that will make it competitive with, or superior to, a conventional digital computer for the adaptive optics application. An optimization of the adaptive optics correction algorithm with respect to an optical processor's degree of accuracy is also briefly discussed.

  9. Very Large Telescope Adaptive Optics Community Days Report on the ESO Workshop

    Science.gov (United States)

    Leibundgut, B.; Kasper, M.; Kuntschner, H.

    2016-12-01

    The future of adaptive optics (AO) instruments at the VLT was discussed during a two-day workshop. Three major directions emerged from these discussions: adaptive optics in the optical; multi-object adaptive optics (MOAO); and extreme adaptive optics (XAO). The science cases for these three options were presented and the discussions are summarised. ESO is now planning to provide detailed science cases for an optical AO system and to prepare upgrade plans for XAO and MOAO.

  10. Active optics in Large Synoptic Survey Telescope

    Science.gov (United States)

    Liang, Ming; Krabbendam, Victor; Claver, Charles F.; Chandrasekharan, Srinivasan; Xin, Bo

    2012-09-01

    The Large Synoptic Survey Telescope (LSST) has a 3.5º field of view and F/1.2 focus that makes the performance quite sensitive to the perturbations of misalignments and mirror surface deformations. In order to maintain the image quality, LSST has an active optics system (AOS) to measure and correct those perturbations in a closed loop. The perturbed wavefront errors are measured by the wavefront sensors (WFS) located at the four corners of the focal plane. The perturbations are solved by the non-linear least square algorithm by minimizing the rms variation of the measured and baseline designed wavefront errors. Then the correction is realized by applying the inverse of the perturbations to the optical system. In this paper, we will describe the correction processing in the LSST AOS. We also will discuss the application of the algorithm, the properties of the sensitivity matrix and the stabilities of the correction. A simulation model, using ZEMAX as a ray tracing engine and MATLAB as an analysis platform, is set up to simulate the testing and correction loop of the LSST AOS. Several simulation examples and results are presented.

  11. Wavelet methods in multi-conjugate adaptive optics

    CERN Document Server

    Helin, Tapio

    2013-01-01

    The next generation ground-based telescopes rely heavily on adaptive optics for overcoming the limitation of atmospheric turbulence. In the future adaptive optics modalities, like multi-conjugate adaptive optics (MCAO), atmospheric tomography is the major mathematical and computational challenge. In this severely ill-posed problem a fast and stable reconstruction algorithm is needed that can take into account many real-life phenomena of telescope imaging. We introduce a novel reconstruction method for the atmospheric tomography problem and demonstrate its performance and flexibility in the context of MCAO. Our method is based on using locality properties of compactly supported wavelets, both in the spatial and frequency domain. The reconstruction in the atmospheric tomography problem is obtained by solving the Bayesian MAP estimator with a conjugate gradient based algorithm. An accelerated algorithm with preconditioning is also introduced. Numerical performance is demonstrated on the official end-to-end simul...

  12. Beaconless adaptive-optics technique for HEL beam control

    Science.gov (United States)

    Khizhnyak, Anatoliy; Markov, Vladimir

    2016-05-01

    Effective performance of forthcoming laser systems capable of power delivery on a distant target requires an adaptive optics system to correct atmospheric perturbations on the laser beam. The turbulence-induced effects are responsible for beam wobbling, wandering, and intensity scintillation, resulting in degradation of the beam quality and power density on the target. Adaptive optics methods are used to compensate for these negative effects. In its turn, operation of the AOS system requires a reference wave that can be generated by the beacon on the target. This report discusses a beaconless approach for wavefront correction with its performance based on the detection of the target-scattered light. Postprocessing of the beacon-generated light field enables retrieval and detailed characterization of the turbulence-perturbed wavefront -data that is essential to control the adaptive optics module of a high-power laser system.

  13. Wavelet methods in multi-conjugate adaptive optics

    Science.gov (United States)

    Helin, T.; Yudytskiy, M.

    2013-08-01

    The next generation ground-based telescopes rely heavily on adaptive optics for overcoming the limitation of atmospheric turbulence. In the future adaptive optics modalities, like multi-conjugate adaptive optics (MCAO), atmospheric tomography is the major mathematical and computational challenge. In this severely ill-posed problem, a fast and stable reconstruction algorithm is needed that can take into account many real-life phenomena of telescope imaging. We introduce a novel reconstruction method for the atmospheric tomography problem and demonstrate its performance and flexibility in the context of MCAO. Our method is based on using locality properties of compactly supported wavelets, both in the spatial and frequency domains. The reconstruction in the atmospheric tomography problem is obtained by solving the Bayesian MAP estimator with a conjugate-gradient-based algorithm. An accelerated algorithm with preconditioning is also introduced. Numerical performance is demonstrated on the official end-to-end simulation tool OCTOPUS of European Southern Observatory.

  14. Accuracy requirements of optical linear algebra processors in adaptive optics imaging systems.

    Science.gov (United States)

    Downie, J D; Goodman, J W

    1989-10-15

    A ground-based adaptive optics imaging telescope system attempts to improve image quality by measuring and correcting for atmospherically induced wavefront aberrations. The necessary control computations during each cycle will take a finite amount of time, which adds to the residual error variance since the atmosphere continues to change during that time. Thus an optical processor may be well-suited for this task. This paper investigates this possibility by studying the accuracy requirements in a general optical processor that will make it competitive with, or superior to, a conventional digital computer for adaptive optics use.

  15. Adaptive optics technology for high-resolution retinal imaging.

    Science.gov (United States)

    Lombardo, Marco; Serrao, Sebastiano; Devaney, Nicholas; Parravano, Mariacristina; Lombardo, Giuseppe

    2012-12-27

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging.

  16. Adaptive Optics Technology for High-Resolution Retinal Imaging

    Directory of Open Access Journals (Sweden)

    Giuseppe Lombardo

    2012-12-01

    Full Text Available Adaptive optics (AO is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging.

  17. Surface Plasmon Wave Adapter Designed with Transformation Optics

    DEFF Research Database (Denmark)

    Zhang, Jingjing; Xiao, Sanshui; Wubs, Martijn

    2011-01-01

    On the basis of transformation optics, we propose the design of a surface plasmon wave adapter which confines surface plasmon waves on non-uniform metal surfaces and enables adiabatic mode transformation of surface plasmon polaritons with very short tapers. This adapter can be simply achieved...... with homogeneous anisotropic naturally occurring materials or subwavelength grating-structured dielectric materials. Full wave simulations based on a finite-element method have been performed to validate our proposal....

  18. Surface Plasmon Wave Adapter Designed with Transformation Optics

    DEFF Research Database (Denmark)

    Zhang, Jingjing; Xiao, Sanshui; Wubs, Martijn;

    2011-01-01

    On the basis of transformation optics, we propose the design of a surface plasmon wave adapter which confines surface plasmon waves on non-uniform metal surfaces and enables adiabatic mode transformation of surface plasmon polaritons with very short tapers. This adapter can be simply achieved...... with homogeneous anisotropic naturally occurring materials or subwavelength grating-structured dielectric materials. Full wave simulations based on a finite-element method have been performed to validate our proposal....

  19. Holographic fluorescence microscopy with incoherent digital holographic adaptive optics.

    Science.gov (United States)

    Jang, Changwon; Kim, Jonghyun; Clark, David C; Lee, Seungjae; Lee, Byoungho; Kim, Myung K

    2015-01-01

    Introduction of adaptive optics technology into astronomy and ophthalmology has made great contributions in these fields, allowing one to recover images blurred by atmospheric turbulence or aberrations of the eye. Similar adaptive optics improvement in microscopic imaging is also of interest to researchers using various techniques. Current technology of adaptive optics typically contains three key elements: a wavefront sensor, wavefront corrector, and controller. These hardware elements tend to be bulky, expensive, and limited in resolution, involving, for example, lenslet arrays for sensing or multiactuator deformable mirrors for correcting. We have previously introduced an alternate approach based on unique capabilities of digital holography, namely direct access to the phase profile of an optical field and the ability to numerically manipulate the phase profile. We have also demonstrated that direct access and compensation of the phase profile are possible not only with conventional coherent digital holography, but also with a new type of digital holography using incoherent light: selfinterference incoherent digital holography (SIDH). The SIDH generates a complex—i.e., amplitude plus phase—hologram from one or several interferograms acquired with incoherent light, such as LEDs, lamps, sunlight, or fluorescence. The complex point spread function can be measured using guide star illumination and it allows deterministic deconvolution of the full-field image. We present experimental demonstration of aberration compensation in holographic fluorescence microscopy using SIDH. Adaptive optics by SIDH provides new tools for improved cellular fluorescence microscopy through intact tissue layers or other types of aberrant media.

  20. Characterization and Operation of Liquid Crystal Adaptive Optics Phoropter

    Energy Technology Data Exchange (ETDEWEB)

    Awwal, A; Bauman, B; Gavel, D; Olivier, S; Jones, S; Hardy, J L; Barnes, T; Werner, J S

    2003-02-05

    Adaptive optics (AO), a mature technology developed for astronomy to compensate for the effects of atmospheric turbulence, can also be used to correct the aberrations of the eye. The classic phoropter is used by ophthalmologists and optometrists to estimate and correct the lower-order aberrations of the eye, defocus and astigmatism, in order to derive a vision correction prescription for their patients. An adaptive optics phoropter measures and corrects the aberrations in the human eye using adaptive optics techniques, which are capable of dealing with both the standard low-order aberrations and higher-order aberrations, including coma and spherical aberration. High-order aberrations have been shown to degrade visual performance for clinical subjects in initial investigations. An adaptive optics phoropter has been designed and constructed based on a Shack-Hartmann sensor to measure the aberrations of the eye, and a liquid crystal spatial light modulator to compensate for them. This system should produce near diffraction-limited optical image quality at the retina, which will enable investigation of the psychophysical limits of human vision. This paper describes the characterization and operation of the AO phoropter with results from human subject testing.

  1. Holographic fluorescence microscopy with incoherent digital holographic adaptive optics

    Science.gov (United States)

    Jang, Changwon; Kim, Jonghyun; Clark, David C.; Lee, Seungjae; Lee, Byoungho; Kim, Myung K.

    2015-11-01

    Introduction of adaptive optics technology into astronomy and ophthalmology has made great contributions in these fields, allowing one to recover images blurred by atmospheric turbulence or aberrations of the eye. Similar adaptive optics improvement in microscopic imaging is also of interest to researchers using various techniques. Current technology of adaptive optics typically contains three key elements: a wavefront sensor, wavefront corrector, and controller. These hardware elements tend to be bulky, expensive, and limited in resolution, involving, for example, lenslet arrays for sensing or multiactuator deformable mirrors for correcting. We have previously introduced an alternate approach based on unique capabilities of digital holography, namely direct access to the phase profile of an optical field and the ability to numerically manipulate the phase profile. We have also demonstrated that direct access and compensation of the phase profile are possible not only with conventional coherent digital holography, but also with a new type of digital holography using incoherent light: self­interference incoherent digital holography (SIDH). The SIDH generates a complex-i.e., amplitude plus phase-hologram from one or several interferograms acquired with incoherent light, such as LEDs, lamps, sunlight, or fluorescence. The complex point spread function can be measured using guide star illumination and it allows deterministic deconvolution of the full-field image. We present experimental demonstration of aberration compensation in holographic fluorescence microscopy using SIDH. Adaptive optics by SIDH provides new tools for improved cellular fluorescence microscopy through intact tissue layers or other types of aberrant media.

  2. Adaptation of the methodology of sample surveys for marketing researches

    Directory of Open Access Journals (Sweden)

    Kataev Andrey

    2015-08-01

    Full Text Available The article presents the results of the theory of adaptation of sample survey for the purposes of marketing, that allows to answer the fundamental question of any marketing research – how many objects should be studied for drawing adequate conclusions.

  3. Adaptive Forward Error Correction for Energy Efficient Optical Transport Networks

    DEFF Research Database (Denmark)

    Rasmussen, Anders; Ruepp, Sarah Renée; Berger, Michael Stübert

    2013-01-01

    In this paper we propose a novel scheme for on the fly code rate adjustment for forward error correcting (FEC) codes on optical links. The proposed scheme makes it possible to adjust the code rate independently for each optical frame. This allows for seamless rate adaption based on the link state...... of the optical light path and the required amount of throughput going towards the destination node. The result is a dynamic FEC, which can be used to optimize the connections for throughput and/or energy efficiency, depending on the current demand....

  4. Data-Driven Optimal Control for Adaptive Optics

    NARCIS (Netherlands)

    Hinnen, K.J.G.

    2007-01-01

    Adaptive optics (AO) is a technique to actively correct the wavefront distortions introduced in a light beam as it propagates through a turbulent medium. Nowadays, it is commonly applied in ground-based telescopes to counteract the devastating effect of atmospheric turbulence. This thesis focuses on

  5. eXtreme Adaptive Optics Planet Imager: overview and status

    Science.gov (United States)

    Macintosh, Bruce A.; Bauman, Brian; Wilhelmsen Evans, Julia; Graham, James R.; Lockwood, Christopher; Poyneer, Lisa; Dillon, Daren; Gavel, Don T.; Green, Joseph J.; Lloyd, James P.; Makidon, Russell B.; Olivier, Scot; Palmer, Dave; Perrin, Marshall D.; Severson, Scott; Sheinis, Andrew I.; Sivaramakrishnan, Anand; Sommargren, Gary; Soummer, Remi; Troy, Mitchell; Wallace, J. Kent; Wishnow, Edward

    2004-10-01

    As adaptive optics (AO) matures, it becomes possible to envision AO systems oriented towards specific important scientific goals rather than general-purpose systems. One such goal for the next decade is the direct imaging detection of extrasolar planets. An "extreme" adaptive optics (ExAO) system optimized for extrasolar planet detection will have very high actuator counts and rapid update rates - designed for observations of bright stars - and will require exquisite internal calibration at the nanometer level. In addition to extrasolar planet detection, such a system will be capable of characterizing dust disks around young or mature stars, outflows from evolved stars, and high Strehl ratio imaging even at visible wavelengths. The NSF Center for Adaptive Optics has carried out a detailed conceptual design study for such an instrument, dubbed the eXtreme Adaptive Optics Planet Imager or XAOPI. XAOPI is a 4096-actuator AO system, notionally for the Keck telescope, capable of achieving contrast ratios >107 at angular separations of 0.2-1". ExAO system performance analysis is quite different than conventional AO systems - the spatial and temporal frequency content of wavefront error sources is as critical as their magnitude. We present here an overview of the XAOPI project, and an error budget highlighting the key areas determining achievable contrast. The most challenging requirement is for residual static errors to be less than 2 nm over the controlled range of spatial frequencies. If this can be achieved, direct imaging of extrasolar planets will be feasible within this decade.

  6. Wavefront Control for Space Telescope Applications Using Adaptive Optics

    Science.gov (United States)

    2007-12-01

    science and chemistry . Although many of the principles behind adaptive optics have been understood for quite some time it hasn’t been until recent... SIMULINK and DSPACE by applying a voltage between +/-5 volts. Figure 11 Baker One Inch Fast Steering Mirror 16 E. POSITION SENSING MODULE

  7. On the influence of the Illuminati in astronomical adaptive optics

    CERN Document Server

    Morzinski, Katie M

    2012-01-01

    Astronomical adaptive optics (AO) has come into its own. Major O/IR telescopes are achieving diffraction-limited imaging; major facilities are being built with AO as an integral part. To the layperson, it may seem that AO has developed along a serpentine path. However, with a little illumination, the mark of Galileo's heirs becomes apparent in explaining the success of AO.

  8. Adaptive optics at Lick Observatory: system architecture and operations

    Science.gov (United States)

    Brase, James M.; An, Jong; Avicola, Kenneth; Bissinger, Horst D.; Friedman, Herbert W.; Gavel, Donald T.; Johnston, Brooks; Max, Claire E.; Olivier, Scot S.; Presta, Robert W.; Rapp, David A.; Salmon, J. Thaddeus; Waltjen, Kenneth E.; Fisher, William A.

    1994-05-01

    We will describe an adaptive optics system developed for the 1 meter Nickel and 3 meter Shane telescopes at Lick Observatory. Observing wavelengths will be in the visible for the 1 meter telescope and in the near IR on the 3 meter. The adaptive optics system design is based on a 69 actuator continuous surface deformable mirror and a Hartmann wavefront sensor equipped with an intensified CCD framing camera. The system has been tested at the Cassegrain focus of the 1 meter telescope where the subaperture size is 12.5 cm. The wavefront control calculations are performed on a four processor single board computer controlled by a Unix-based system. We will describe the optical system and give details of the wavefront control system design. We will present predictions of the system performance and initial test results.

  9. The AVES adaptive optics spectrograph for the VLT: status report

    Science.gov (United States)

    Pallavicini, Roberto; Delabre, Bernard; Pasquini, Luca; Zerbi, Filippo M.; Bonanno, Giovanni; Comari, Maurizio; Conconi, Paolo; Mazzoleni, Ruben; Santin, Paolo; Damiani, Francesco; Di Marcantonio, Paolo; Franchini, Mariagrazia; Spano, Paolo; Bonifacio, P.; Catalano, Santo; Molaro, Paolo P.; Randich, S.; Rodono, Marcello

    2003-03-01

    We report on the status of AVES, the Adaptive-optics Visual Echelle Spectrograph proposed for the secondary port of the Nasmyth Adaptive Optics System (NAOS) recently installed at the VLT. AVES is an intermediate resolution (R ≍ 16,000) high-efficiency fixed- format echelle spectrograph which operates in the spectral band 500 - 1,000 nm. In addition to a high intrinsic efficiency, comparable to that of ESI at Keck II, it takes advantage of the adaptive optics correction provided by NAOS to reduce the sky and detector contribution in background-limited observations of weak sources, thus allowing a further magnitude gain with respect to comparable non-adaptive optics spectrographs. Simulations show that the instrument will be capable of reaching a magnitude V = 22.5 at S/N > 10 in two hours, two magnitudes weaker than GIRAFFE at the same resolution and 3 magnitudes weaker than the higher resolution UVES spectrograph. Imaging and coronographic functions have also been implemented in the design. We present the results of the final design study and we dicuss the technical and operational issues related to its implementation at the VLT as a visitor instrument. We also discuss the possibility of using a scaled-up non-adaptive optics version of the same design as an element of a double- or triple-arm intermediate-resolution spectrograph for the VLT. Such an option looks attractive in the context of a high-efficiency large-bandwidth (320 - 1,500 nm) spectrograph ("fast-shooter") being considered by ESO as a 2nd-generation VLT instrument.

  10. Wavefront sensors for adaptive optical systems

    Science.gov (United States)

    Lukin, V. P.; Botygina, N. N.; Emaleev, O. N.; Konyaev, P. A.

    2010-10-01

    A high precision Shack-Hartmann wavefront (WF) sensor has been developed on the basis of a low-aperture off-axis diffraction lens array. The device is capable of measuring WF slopes at array sub-apertures of size 640x640 μm with an error not exceeding 4.80 arcsec (0.15 pixel), which corresponds to the standard deviation equal to 0.017λ at the reconstructed WF with wavelength λ . Also the modification of this sensor for adaptive system of solar telescope using extended scenes as tracking objects, such as sunspot, pores, solar granulation and limb, is presented. The software package developed for the proposed WF sensors includes three algorithms of local WF slopes estimation (modified centroids, normalized cross-correlation and fast Fourier-demodulation), as well as three methods of WF reconstruction (modal Zernike polynomials expansion, deformable mirror response functions expansion and phase unwrapping), that can be selected during operation with accordance to the application.

  11. Optical interferometry and adaptive optics of bright transients

    CERN Document Server

    Millour, Florentin; Meilland, Anthony; Nardetto, Nicolas

    2014-01-01

    Bright optical transients (i.e. transients typically visible with the naked eye) are populated mainly by novae eruptions plus a few supernovae (among which the SN1987a event). One bright nova happen every two years, either in the North ot in the South hemisphere. It occurs that current interferometers have matching sensitivities, with typically visible or infrared limiting magnitude in the range 5--7. The temporal development of the fireball, followed by a dust formation phase or the appearance of many coronal lines can be sudied with the Very Large Telescope Interferometer. The detailed geometry of the first phases of novae in outburst remains virtually unexplored. This paper summarizes the work which has been done to date using the VLTI.

  12. Probing other solar systems with current and future adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B; Marois, C; Phillion, D; Poyneer, L; Graham, J; Zuckerman, B; Gavel, D; Veran, J; Wilhelmsen-Evans, J; Mellis, C

    2008-09-08

    Over the past decade, the study of extrasolar planets through indirect techniques--primarily Doppler measurements--has revolutionized our understanding of other solar systems. The next major step in this field will be the direct detection and characterization, via imaging and spectroscopy, of the planets themselves. To achieve this, we must separate the light from the faint planet from the extensive glare of its parent star. We pursued this goal using the current generation of adaptive optics (AO) systems on large ground-based telescopes, using infrared imaging to search for the thermal emission from young planets and developing image processing techniques to distinguish planets from telescope-induced artifacts. Our new Angular Differential Imaging (ADI) technique, which uses the sidereal rotation of the Earth and telescope, is now standard for ground-based high-contrast imaging. Although no young planets were found in our surveys, we placed the strongest limits yet on giant planets in wide orbits (>30 AU) around young stars and characterized planetary companion candidates. The imaging of planetary companions on solar-system-like scales (5-30 AU) will require a new generation of advanced AO systems that are an order of magnitude more powerful than the LLNL-built Keck AO system. We worked to develop and test the key technologies needed for these systems, including a spatially-filtered wavefront sensor, efficient and accurate wavefront reconstruction algorithms, and precision AO wavefront control at the sub-nm level. LLNL has now been selected by the Gemini Observatory to lead the construction of the Gemini Planet Imager, a $24M instrument that will be the most advanced AO system in the world.

  13. Probing other solar systems with current and future adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B; Marois, C; Phillion, D; Poyneer, L; Graham, J; Zuckerman, B; Gavel, D; Veran, J; Wilhelmsen-Evans, J; Mellis, C

    2008-09-08

    Over the past decade, the study of extrasolar planets through indirect techniques--primarily Doppler measurements--has revolutionized our understanding of other solar systems. The next major step in this field will be the direct detection and characterization, via imaging and spectroscopy, of the planets themselves. To achieve this, we must separate the light from the faint planet from the extensive glare of its parent star. We pursued this goal using the current generation of adaptive optics (AO) systems on large ground-based telescopes, using infrared imaging to search for the thermal emission from young planets and developing image processing techniques to distinguish planets from telescope-induced artifacts. Our new Angular Differential Imaging (ADI) technique, which uses the sidereal rotation of the Earth and telescope, is now standard for ground-based high-contrast imaging. Although no young planets were found in our surveys, we placed the strongest limits yet on giant planets in wide orbits (>30 AU) around young stars and characterized planetary companion candidates. The imaging of planetary companions on solar-system-like scales (5-30 AU) will require a new generation of advanced AO systems that are an order of magnitude more powerful than the LLNL-built Keck AO system. We worked to develop and test the key technologies needed for these systems, including a spatially-filtered wavefront sensor, efficient and accurate wavefront reconstruction algorithms, and precision AO wavefront control at the sub-nm level. LLNL has now been selected by the Gemini Observatory to lead the construction of the Gemini Planet Imager, a $24M instrument that will be the most advanced AO system in the world.

  14. Nonlinear optical crystals a complete survey

    CERN Document Server

    Nikogosyan, David N

    2005-01-01

    Nonlinear optical crystals are widely used in modern optical science and technology for frequency conversion of laser light, i.e. to generate laser radiation at any specific wavelength in visible, UV or IR spectral regions. This unrivalled reference book contains the most complete and up-to-date information on properties of nonlinear optical crystals. It includes: * Database of 63 common and novel nonlinear optical crystals * Periodically-poled and self-frequency-doubling materials * Full description of linear and nonlinear optical properties * Significant amount of crystallophysical, thermophysical, spectroscopic, electro-optic and magneto-optic information * 7 mini-reviews on novel applications, such as deep-UV light generation, terahertz-wave generation, ultrashort laser pulse compression, photonic band-gap crystals, x3 nonlinearity, etc. * More than 1500 different references with full titles It is a vital source of information for scientists and engineers dealing with modern applications of nonlinear opti...

  15. Pixelized Device Control Actuators for Large Adaptive Optics

    Science.gov (United States)

    Knowles, Gareth J.; Bird, Ross W.; Shea, Brian; Chen, Peter

    2009-01-01

    A fully integrated, compact, adaptive space optic mirror assembly has been developed, incorporating new advances in ultralight, high-performance composite mirrors. The composite mirrors use Q-switch matrix architecture-based pixelized control (PMN-PT) actuators, which achieve high-performance, large adaptive optic capability, while reducing the weight of present adaptive optic systems. The self-contained, fully assembled, 11x11x4-in. (approx.= 28x28x10-cm) unit integrates a very-high-performance 8-in. (approx.=20-cm) optic, and has 8-kHz true bandwidth. The assembled unit weighs less than 15 pounds (=6.8 kg), including all mechanical assemblies, power electronics, control electronics, drive electronics, face sheet, wiring, and cabling. It requires just three wires to be attached (power, ground, and signal) for full-function systems integration, and uses a steel-frame and epoxied electronics. The three main innovations are: 1. Ultralightweight composite optics: A new replication method for fabrication of very thin composite 20-cm-diameter laminate face sheets with good as-fabricated optical figure was developed. The approach is a new mandrel resin surface deposition onto previously fabricated thin composite laminates. 2. Matrix (regenerative) power topology: Waveform correction can be achieved across an entire face sheet at 6 kHz, even for large actuator counts. In practice, it was found to be better to develop a quadrant drive, that is, four quadrants of 169 actuators behind the face sheet. Each quadrant has a single, small, regenerative power supply driving all 169 actuators at 8 kHz in effective parallel. 3. Q-switch drive architecture: The Q-switch innovation is at the heart of the matrix architecture, and allows for a very fast current draw into a desired actuator element in 120 counts of a MHz clock without any actuator coupling.

  16. Adaptive Quality of Transmission Control in Elastic Optical Network

    Science.gov (United States)

    Cai, Xinran

    Optical fiber communication is becoming increasingly important due to the burgeoning demand in the internet capacity. However, traditional wavelength division multiplexing (WDM) technique fails to address such demand because of its inefficient spectral utilization. As a result, elastic optical networking (EON) has been under extensive investigation recently. Such network allows sub-wavelength and super-wavelength channel accommodation, and mitigates the stranded bandwidth problem in the WDM network. In addition, elastic optical network is also able to dynamically allocate the spectral resources of the network based on channel conditions and impairments, and adaptively control the quality of transmission of a channel. This application requires two aspects to be investigated: an efficient optical performance monitoring scheme and networking control and management algorithms to reconfigure the network in a dynamic fashion. This thesis focuses on the two aspects discussed above about adaptive QoT control. We demonstrated a supervisory channel method for optical signal to noise ratio (OSNR) and chromatic dispersion (CD) monitoring. In addition, our proof-of-principle testbed experiments show successful impairment aware reconfiguration of the network with modulation format switching (MFS) only and MFS combined with lightpath rerouting (LR) for hundred-GHz QPSK superchannels undergoing time-varying OSNR impairment.

  17. Segmented bimorph mirrors for adaptive optics: morphing strategy.

    Science.gov (United States)

    Bastaits, Renaud; Alaluf, David; Belloni, Edoardo; Rodrigues, Gonçalo; Preumont, André

    2014-08-01

    This paper discusses the concept of a light weight segmented bimorph mirror for adaptive optics. It focuses on the morphing strategy and addresses the ill-conditioning of the Jacobian of the segments, which are partly outside the optical pupil. Two options are discussed, one based on truncating the singular values and one called damped least squares, which minimizes a combined measure of the sensor error and the voltage vector. A comparison of various configurations of segmented mirrors was conducted; it is shown that segmentation sharply increases the natural frequency of the system with limited deterioration of the image quality.

  18. Adaptive optics for improved retinal surgery and diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Humayun, M S; Sadda, S R; Thompson, C A; Olivier, S S; Kartz, M W

    2000-08-21

    It is now possible to field a compact adaptive optics (AO) system on a surgical microscope for use in retinal diagnostics and surgery. Recent developments in integrated circuit technology and optical photonics have led to the capability of building an AO system that is compact and significantly less expensive than traditional AO systems. It is foreseen that such an AO system can be integrated into a surgical microscope while maintaining a package size of a lunchbox. A prototype device can be developed in a manner that lends itself well to large-scale manufacturing.

  19. Results from the adaptive optics coronagraph at the WHT

    CERN Document Server

    Thompson, S J; Bingham, R G; Charalambous, A; Myers, R M; Bissonauth, N; Clark, P; Talbot, G

    2005-01-01

    Described here is the design and commissioning of a coronagraph facility for the 4.2 metre William Herschel Telescope (WHT) and its Nasmyth Adaptive Optics system for Multi-purpose Instrumentation (NAOMI). The use of the NAOMI system gives an improved image resolution of ~0.15 arcsecs at a wavelength of 2.2um. This enables the Optimised Stellar Coronagraph for Adaptive optics (OSCA) to suppress stellar light using smaller occulting masks and thus allows regions closer to bright astronomical objects to be imaged. OSCA provides a selection of 10 different occulting masks with sizes of 0.25 - 2.0 arcsecs in diameter, including two with full greyscale Gaussian profiles. There is also a choice of different sized and shaped Lyot stops (pupil plane masks). Computer simulations of the different coronagraphic options with the NAOMI segmented mirror have relevance for the next generation of highly segmented extremely large telescopes.

  20. Laser Guide Star Adaptive Optics without Tip-tilt

    CERN Document Server

    Davies, R; Lidman, C; Louarn, M Le; Kasper, M; Förster-Schreiber, N M; Roccatagliata, V; Ageorges, N; Amico, P; Dumas, C; Mannucci, F

    2008-01-01

    Adaptive optics (AO) systems allow a telescope to reach its diffraction limit at near infrared wavelengths. But to achieve this, a bright natural guide star (NGS) is needed for the wavefront sensing, severely limiting the fraction of the sky over which AO can be used. To some extent this can be overcome with a laser guide star (LGS). While the laser can be pointed anywhere in the sky, one still needs to have a natural star, albeit fainter, reasonably close to correct the image motion (tip-tilt) to which laser guide stars are insensitive. There are in fact many astronomical targets without suitable tip-tilt stars, but for which the enhanced resolution obtained with the Laser Guide Star Facility (LGSF) would still be very beneficial. This article explores what adaptive optics performance one might expect if one dispenses with the tip-tilt star, and in what situations this mode of observing might be needed.

  1. MEMS-based extreme adaptive optics for planet detection

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B A; Graham, J R; Oppenheimer, B; Poyneer, L; Sivaramakrishnan, A; Veran, J

    2005-11-18

    The next major step in the study of extrasolar planets will be the direct detection, resolved from their parent star, of a significant sample of Jupiter-like extrasolar giant planets. Such detection will open up new parts of the extrasolar planet distribution and allow spectroscopic characterization of the planets themselves. Detecting Jovian planets at 5-50 AU scale orbiting nearby stars requires adaptive optics systems and coronagraphs an order of magnitude more powerful than those available today--the realm of ''Extreme'' adaptive optics. We present the basic requirements and design for such a system, the Gemini Planet Imager (GPI.) GPI will require a MEMS-based deformable mirror with good surface quality, 2-4 micron stroke (operated in tandem with a conventional low-order ''woofer'' mirror), and a fully-functional 48-actuator-diameter aperture.

  2. Laser Tomography Adaptive Optics (LTAO): A performance study

    CERN Document Server

    Tatulli, E

    2013-01-01

    We present an analytical derivation of the on-axis performance of Adaptive Optics systems using a given number of guide stars of arbitrary altitude, distributed at arbitrary angular positions in the sky. The expressions of the residual error are given for cases of both continuous and discrete turbulent atmospheric profiles. Assuming Shack-Hartmann wavefront sensing with circular apertures, we demonstrate that the error is formally described by integrals of products of three Bessel functions. We compare the performance of Adaptive Optics correction when using natural, Sodium or Rayleigh laser guide stars. For small diameter class telescopes (~5m), we show that a few number of Rayleigh beacons can provide similar performance to that of a single Sodium laser, for a lower overall cost of the instrument. For bigger apertures, using Rayleigh stars may not be such a suitable alternative because of the too severe cone effect that drastically degrades the quality of the correction.

  3. Nanolubrication of sliding components in adaptive optics used in microprojectors

    Science.gov (United States)

    Bhushan, Bharat; Lee, Hyungoo; Chaparala, Satish C.; Bhatia, Vikram

    2010-10-01

    Integrated microprojectors are being developed to project a large image on any surface chosen by the users. For a laser-based microprojector, a piezo-electric based adaptive optics unit is adopted in the green laser architecture. The operation of this unit depends on stick-slip motion between the sliding components. Nanolubrication of adaptive optics sliding components is needed to reduce wear and for smooth operation. In this study, a methodology to measure lubricant thickness distribution with a nanoscale resolution is developed. Friction, adhesion, and wear mechanisms of lubricant on the sliding components are studied. Effect of actual composite components, scan direction, scale effect, temperature, and humidity to correlate AFM data with the microscale device performance is studied.

  4. Closed-loop adaptive optical system with a liquid mirror.

    Science.gov (United States)

    Vdovin, Gleb

    2009-02-15

    A deformable mirror based on internal reflection from an electrostatically deformable liquid-air interface is proposed and investigated. A differential equation describing the static behavior of such a mirror is analyzed and solved numerically. Stable closed-loop operation of an adaptive optical system with a liquid deformable mirror is demonstrated, including forming and the correction of low-order aberrations described by Zernike polynomials and the real-time correction of dynamically changing aberrations.

  5. Wavefront Reconstruction and Mirror Surface Optimizationfor Adaptive Optics

    Science.gov (United States)

    2014-06-01

    correction. A DM has a reflective surface with actuators along the back struc- ture that apply forces causing the mirror surface to adapt to a desired shape...actuators. The actuators cause forces along the back of the mirror structure and the mirror surface deflects to form the conjugate shape of the wavefront...optical axis of the primary mirror. The interferometer and null corrector are mounted to remove the 81 Interferometer Null corrector Hexapod ❋✐❣✉r

  6. Limits of spherical blur determined with an adaptive optics mirror.

    Science.gov (United States)

    Atchison, David A; Guo, Huanqing; Fisher, Scott W

    2009-05-01

    We extended an earlier study (Vision Research, 45, 1967-1974, 2005) in which we investigated limits at which induced blur of letter targets becomes noticeable, troublesome and objectionable. Here we used a deformable adaptive optics mirror to vary spherical defocus for conditions of a white background with correction of astigmatism; a white background with reduction of all aberrations other than defocus; and a monochromatic background with reduction of all aberrations other than defocus. We used seven cyclopleged subjects, lines of three high-contrast letters as targets, 3-6 mm artificial pupils, and 0.1-0.6 logMAR letter sizes. Subjects used a method of adjustment to control the defocus component of the mirror to set the 'just noticeable', 'just troublesome' and 'just objectionable' defocus levels. For the white-no adaptive optics condition combined with 0.1 logMAR letter size, mean 'noticeable' blur limits were +/-0.30, +/-0.24 and +/-0.23 D at 3, 4 and 6 mm pupils, respectively. White-adaptive optics and monochromatic-adaptive optics conditions reduced blur limits by 8% and 20%, respectively. Increasing pupil size from 3-6 mm decreased blur limits by 29%, and increasing letter size increased blur limits by 79%. Ratios of troublesome to noticeable, and of objectionable to noticeable, blur limits were 1.9 and 2.7 times, respectively. The study shows that the deformable mirror can be used to vary defocus in vision experiments. Overall, the results of noticeable, troublesome and objectionable blur agreed well with those of the previous study. Attempting to reduce higher-order aberrations or chromatic aberrations, reduced blur limits to only a small extent.

  7. Robotic Laser-Adaptive-Optics Imaging of 715 Kepler Exoplanet Candidates using Robo-AO

    CERN Document Server

    Law, Nicholas M; Baranec, Christoph; Riddle, Reed; Ravichandran, Ganesh; Ziegler, Carl; Johnson, John Asher; Tendulkar, Shriharsh P; Bui, Khanh; Burse, Mahesh P; Das, H K; Dekany, Richard G; Kulkarni, Shrinivas; Punnadi, Sujit; Ramaprakash, A N

    2013-01-01

    The Robo-AO Kepler Planetary Candidate Survey is designed to observe every Kepler planet candidate host star with laser adaptive optics imaging to search for blended nearby stars, which may be physically associated companions and/or responsible for transit false positives. In this paper we present the results from the 2012 observing season, searching for stars close to 715 representative Kepler planet candidate hosts. We find 53 companions, 44 of which are new discoveries. We detail the Robo-AO survey data reduction methods including a method of using the large ensemble of target observations as mutual point-spread-function references, along with a new automated companion-detection algorithm designed for large adaptive optics surveys. Our survey is sensitive to objects from 0.15" to 2.5" separation, with contrast ratios up to delta-m~6. We measure an overall nearby-star-probability for Kepler planet candidates of 7.4% +/- 1.0%, and calculate the effects of each detected nearby star on the Kepler-measured plan...

  8. Stellar populations from adaptive optics observations four test cases

    CERN Document Server

    Bedding, T R; Courbin, F; Sams, B J

    1997-01-01

    We describe a first attempt to apply adaptive optics to the study of resolved stellar populations in galaxies. Advantages over traditional approaches are (i) improved spatial resolution and point-source sensitivity through adaptive optics, and (ii) use of the near-infrared region, where the peak of the spectral energy distribution for old populations is found. Disadvantages are the small area covered and the need for excellent seeing. We made observations with the ADONIS system at the European Southern Observatory of the peculiar elliptical galaxy NGC 5128; the irregular galaxy IC 5152 (a possible outer member of the Local Group); the Sc galaxy NGC 300 (a member of the Sculptor group); and the Sgr window in the bulge of the Milky Way. These different fields give excellent test cases for the potential of adaptive optics. In the first two cases, we failed to obtain photometry of individual stars, which would have required excellent seeing. For NGC 300 we measured magnitudes for nine individual supergiants (H = ...

  9. Adaptive optics with pupil tracking for high resolution retinal imaging.

    Science.gov (United States)

    Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Harms, Fabrice; Dainty, Chris

    2012-02-01

    Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware. We also present the first experiments done with a compact adaptive optics flood illumination fundus camera where it was possible to compensate for the higher order aberrations of a moving model eye and in vivo in real time based on pupil tracking measurements, without the real time contribution of a wavefront sensor. As an outcome of this research, we showed that pupil tracking can be effectively used as a low cost and practical adaptive optics tool for high resolution retinal imaging because eye movements constitute an important part of the ocular wavefront dynamics.

  10. Recent progress on the portable solar adaptive optics

    Science.gov (United States)

    Ren, Deqing; Zhang, Xi; Penn, Matt; Wang, Haimin; Dou, Jiangpei; Zhu, Yongtian; Rong, Li; Wang, Xue

    2012-07-01

    The portable solar adaptive optics is a compact adaptive optics system that will be the first visitor solar instrument in the world. As so, it will be able to work with any solar telescope with a aperture size up to ~ 2.0 meters, which will cover the largest solar telescope currently operational. The portable AO features small physical size, high-flexibility and high-performance, and is a duplicable and affordable system. It will provide wave-front correction down to the 0.5-μm wavelength, and will be used for solar high-resolution imaging in the near infrared and the visible. It will be the first AO system that uses LabVIEW based high quality parallel and block-diagram programming, which fully takes advantage of today's multi-core CPUs, and makes a rapid development of an AO system possible. In this publication, we report our recent progress on the portable adaptive optics, which includes the laboratory test for performance characterization, and initial on-site scientific observations.

  11. Optimizing Photon Collection from Point Sources with Adaptive Optics

    Science.gov (United States)

    Hill, Alexander; Hervas, David; Nash, Joseph; Graham, Martin; Burgers, Alexander; Paudel, Uttam; Steel, Duncan; Kwiat, Paul

    2015-05-01

    Collection of light from point-like sources is typically poor due to the optical aberrations present with very high numerical-aperture optics. In the case of quantum dots, the emitted mode is nonisotropic and may be quite difficult to couple into single- or even few-mode fiber. Wavefront aberrations can be corrected using adaptive optics at the classical level by analyzing the wavefront directly (e.g., with a Shack-Hartmann sensor); however, these techniques are not feasible at the single-photon level. We present a new technique for adaptive optics with single photons using a genetic algorithm to optimize collection from point emitters with a deformable mirror. We first demonstrate our technique for improving coupling from a subwavelength pinhole, which simulates isotropic emission from a point source. We then apply our technique in situto InAs/GaAs quantum dots, obtaining coupling increases of up to 50% even in the presence of an artificial source of drift.

  12. Point spread function optimization for STORM using adaptive optics

    Science.gov (United States)

    Forouhesh Tehrani, Kayvan; Kner, Peter

    2014-03-01

    Stochastic Optical Reconstruction Microscopy (STORM) requires a high Strehl ratio point spread function (PSF) to achieve high resolution, especially in the presence of background fluorescence. The PSF is degraded by aberrations caused by imperfections in the optics, the refractive index mismatch between the sample and coverslip, and the refractive index variations of the sample. These aberrations distort the shape of the PSF and increase the PSF width directly reducing the resolution of STORM. Here we discuss the use of Adaptive Optics (AO) to correct aberrations, maintaining a high Strehl ratio even in thick tissue. Because the intensity fluctuates strongly from frame to frame, image intensity is not a reliable measure of PSF quality, and the choice of a robust optimization metric is critical. We demonstrate the use of genetic algorithms with single molecule imaging for optimization of the wavefront and introduce a metric that is relatively insensitive to image intensity. We demonstrate the correction of the wavefront from measurements of single quantum dots.

  13. Anisoplanatism in adaptive optics systems due to pupil aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Bauman, B

    2005-08-01

    Adaptive optics systems typically include an optical relay that simultaneously images the science field to be corrected and also a set of pupil planes conjugate to the deformable mirror of the system. Often, in the optical spaces where DM's are placed, the pupils are aberrated, leading to a displacement and/or distortion of the pupil that varies according to field position--producing a type of anisoplanatism, i.e., a degradation of the AO correction with field angle. The pupil aberration phenomenon is described and expressed in terms of Seidel aberrations. An expression for anisoplanatism as a function of pupil distortion is derived, an example of an off-axis parabola is given, and a convenient method for controlling pupil-aberration-generated anisoplanatism is proposed.

  14. Manufacturing of glassy thin shell for adaptive optics: results achieved

    Science.gov (United States)

    Poutriquet, F.; Rinchet, A.; Carel, J.-L.; Leplan, H.; Ruch, E.; Geyl, R.; Marque, G.

    2012-07-01

    Glassy thin shells are key components for the development of adaptive optics and are part of future & innovative projects such as ELT. However, manufacturing thin shells is a real challenge. Even though optical requirements for the front face - or optical face - are relaxed compared to conventional passive mirrors, requirements concerning thickness uniformity are difficult to achieve. In addition, process has to be completely re-defined as thin mirror generates new manufacturing issues. In particular, scratches and digs requirement is more difficult as this could weaken the shell, handling is also an important issue due to the fragility of the mirror. Sagem, through REOSC program, has recently manufactured different types of thin shells in the frame of European projects: E-ELT M4 prototypes and VLT Deformable Secondary Mirror (VLT DSM).

  15. Adaptive-optics Optical Coherence Tomography Processing Using a Graphics Processing Unit*

    Science.gov (United States)

    Shafer, Brandon A.; Kriske, Jeffery E.; Kocaoglu, Omer P.; Turner, Timothy L.; Liu, Zhuolin; Lee, John Jaehwan; Miller, Donald T.

    2015-01-01

    Graphics processing units are increasingly being used for scientific computing for their powerful parallel processing abilities, and moderate price compared to super computers and computing grids. In this paper we have used a general purpose graphics processing unit to process adaptive-optics optical coherence tomography (AOOCT) images in real time. Increasing the processing speed of AOOCT is an essential step in moving the super high resolution technology closer to clinical viability. PMID:25570838

  16. Adaptive-optics optical coherence tomography processing using a graphics processing unit.

    Science.gov (United States)

    Shafer, Brandon A; Kriske, Jeffery E; Kocaoglu, Omer P; Turner, Timothy L; Liu, Zhuolin; Lee, John Jaehwan; Miller, Donald T

    2014-01-01

    Graphics processing units are increasingly being used for scientific computing for their powerful parallel processing abilities, and moderate price compared to super computers and computing grids. In this paper we have used a general purpose graphics processing unit to process adaptive-optics optical coherence tomography (AOOCT) images in real time. Increasing the processing speed of AOOCT is an essential step in moving the super high resolution technology closer to clinical viability.

  17. Optical properties of photoreceptor and retinal pigment epithelium cells investigated with adaptive optics optical coherence tomography

    Science.gov (United States)

    Liu, Zhuolin

    Human vision starts when photoreceptors collect and respond to light. Photoreceptors do not function in isolation though, but share close interdependence with neighboring photoreceptors and underlying retinal pigment epithelium (RPE) cells. These cellular interactions are essential for normal function of the photoreceptor-RPE complex, but methods to assess these in the living human eye are limited. One approach that has gained increased promise is high-resolution retinal imaging that has undergone tremendous technological advances over the last two decades to probe the living retina at the cellular level. Pivotal in these advances has been adaptive optics (AO) and optical coherence tomography (OCT) that together allow unprecedented spatial resolution of retinal structures in all three dimensions. Using these high-resolution systems, cone photoreceptor are now routinely imaged in healthy and diseased retina enabling fundamental structural properties of cones to be studied such as cell spacing, packing arrangement, and alignment. Other important cell properties, however, have remained elusive to investigation as even better imaging performance is required and thus has resulted in an incomplete understanding of how cells in the photoreceptor-RPE complex interact with light. To address this technical bottleneck, we expanded the imaging capability of AO-OCT to detect and quantify more accurately and completely the optical properties of cone photoreceptor and RPE cells at the cellular level in the living human retina. The first objective of this thesis was development of a new AO-OCT method that is more precise and sensitive, thus enabling a more detailed view of the 3D optical signature of the photoreceptor-RPE complex than was previously possible (Chapter 2). Using this new system, the second objective was quantifying the waveguide properties of individual cone photoreceptor inner and outer segments across the macula (Chapter 3). The third objective extended the AO

  18. Integrated modeling of the GMT laser tomography adaptive optics system

    Science.gov (United States)

    Piatrou, Piotr

    2014-08-01

    Laser Tomography Adaptive Optics (LTAO) is one of adaptive optics systems planned for the Giant Magellan Telescope (GMT). End-to-end simulation tools that are able to cope with the complexity and computational burden of the AO systems to be installed on the extremely large telescopes such as GMT prove to be an integral part of the GMT LTAO system development endeavors. SL95, the Fortran 95 Simulation Library, is one of the software tools successfully used for the LTAO system end-to-end simulations. The goal of SL95 project is to provide a complete set of generic, richly parameterized mathematical models for key elements of the segmented telescope wavefront control systems including both active and adaptive optics as well as the models for atmospheric turbulence, extended light sources like Laser Guide Stars (LGS), light propagation engines and closed-loop controllers. The library is implemented as a hierarchical collection of classes capable of mutual interaction, which allows one to assemble complex wavefront control system configurations with multiple interacting control channels. In this paper we demonstrate the SL95 capabilities by building an integrated end-to-end model of the GMT LTAO system with 7 control channels: LGS tomography with Adaptive Secondary and on-instrument deformable mirrors, tip-tilt and vibration control, LGS stabilization, LGS focus control, truth sensor-based dynamic noncommon path aberration rejection, pupil position control, SLODAR-like embedded turbulence profiler. The rich parameterization of the SL95 classes allows to build detailed error budgets propagating through the system multiple errors and perturbations such as turbulence-, telescope-, telescope misalignment-, segment phasing error-, non-common path-induced aberrations, sensor noises, deformable mirror-to-sensor mis-registration, vibration, temporal errors, etc. We will present a short description of the SL95 architecture, as well as the sample GMT LTAO system simulation

  19. Cellular resolution volumetric in vivo retinal imaging with adaptive optics-optical coherence tomography.

    Science.gov (United States)

    Zawadzki, Robert J; Choi, Stacey S; Fuller, Alfred R; Evans, Julia W; Hamann, Bernd; Werner, John S

    2009-03-02

    Ultrahigh-resolution adaptive optics-optical coherence tomography (UHR-AO-OCT) instrumentation allowing monochromatic and chromatic aberration correction was used for volumetric in vivo retinal imaging of various retinal structures including the macula and optic nerve head (ONH). Novel visualization methods that simplify AO-OCT data viewing are presented, and include co-registration of AO-OCT volumes with fundus photography and stitching of multiple AO-OCT sub-volumes to create a large field of view (FOV) high-resolution volume. Additionally, we explored the utility of Interactive Science Publishing by linking all presented AO-OCT datasets with the OSA ISP software.

  20. Effectiveness of adaptive optics system in satellite-to-ground coherent optical communication.

    Science.gov (United States)

    Jian, Huang; Ke, Deng; Chao, Liu; Peng, Zhang; Dagang, Jiang; Zhoushi, Yao

    2014-06-30

    Adaptive optics (AO) systems can suppress the signal fade induced by atmospheric turbulence in satellite-to-ground coherent optical communication. The lower bound of the signal fade under AO compensation was investigated by analyzing the pattern of aberration modes for a one-stage imaging AO system. The distribution of the root mean square of the residual aberration is discussed on the basis of the spatial and temporal characteristics of the residual aberration of the AO system. The effectiveness of the AO system for improving the performance of coherent optical communication is presented in terms of the bit error rate and system availability.

  1. High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography

    Science.gov (United States)

    Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.

    2010-09-07

    This invention permits retinal images to be acquired at high speed and with unprecedented resolution in three dimensions (4.times.4.times.6 .mu.m). The instrument achieves high lateral resolution by using adaptive optics to correct optical aberrations of the human eye in real time. High axial resolution and high speed are made possible by the use of Fourier-domain optical coherence tomography. Using this system, we have demonstrated the ability to image microscopic blood vessels and the cone photoreceptor mosaic.

  2. Graphite/Cyanate Ester Face Sheets for Adaptive Optics

    Science.gov (United States)

    Bennett, Harold; Shaffer, Joseph; Romeo, Robert

    2008-01-01

    It has been proposed that thin face sheets of wide-aperture deformable mirrors in adaptive-optics systems be made from a composite material consisting of cyanate ester filled with graphite. This composite material appears to offer an attractive alternative to low-thermal-expansion glasses that are used in some conventional optics and have been considered for adaptive-optics face sheets. Adaptive-optics face sheets are required to have maximum linear dimensions of the order of meters or even tens of meters for some astronomical applications. If the face sheets were to be made from low-thermal-expansion glasses, then they would also be required to have thicknesses of the order of a millimeter so as to obtain the optimum compromise between the stiffness needed for support and the flexibility needed to enable deformation to controlled shapes by use of actuators. It is difficult to make large glass sheets having thicknesses less than 3 mm, and 3-mm-thick glass sheets are too stiff to be deformable to the shapes typically required for correction of wavefronts of light that has traversed the terrestrial atmosphere. Moreover, the primary commercially produced candidate low-thermal-expansion glass is easily fractured when in the form of thin face sheets. Graphite-filled cyanate ester has relevant properties similar to those of the low-expansion glasses. These properties include a coefficient of thermal expansion (CTE) of the order of a hundredth of the CTEs of other typical mirror materials. The Young s modulus (which quantifies stiffness in tension and compression) of graphite-filled cyanate ester is also similar to the Young's moduli of low-thermal-expansion glasses. However, the fracture toughness of graphite-filled cyanate ester is much greater than that of the primary candidate low-thermal-expansion glass. Therefore, graphite-filled cyanate ester could be made into nearly unbreakable face sheets, having maximum linear dimensions greater than a meter and thicknesses of

  3. Robotic Transit Follow-up: Adaptive Optics Imaging of Thousands of Stars

    Science.gov (United States)

    Law, Nicholas M.; Morton, T.; Baranec, C.; Riddle, R. L.; Tendulkar, S. P.; Johnson, J. A.; Bui, K.; Burse, M.; Chordia, P.; Das, H.; Dekany, R.; Kulkarni, S. R.; Punnadi, S.; Ramaprakash, A. N.; Robo-AO Collaboration

    2013-01-01

    Stars that host transiting exoplanet candidates may have close companions. If undetected, these companions can produce false-positive planets or affect the measured exoplanet characteristics. High-angular-resolution imaging is required to resolve these systems. Up to now, it has been impossible to obtain adaptive optics images of all the thousands of candidates generated by large surveys like Kepler because of the faintness of the targets and the excessive observing time required. The Robo-AO robotic laser adaptive optics system, newly-commissioned on the Palomar 60-inch telescope, is the first system capable of rapidly observing thousands of targets at high resolution. Robo-AO routinely images 200+ targets per night and produces 0.1" FWHM images in visible wavelengths similar to the Kepler passband. We are using Robo-AO to perform a stellar companion search of unprecedented size, including every Kepler planet candidate and 3,000 nearby planet-search stars. In our first observing season we have imaged over 1,000 Kepler objects of interest and 75% of the Northern stars within 25pc. We will describe the system and discuss its use for future exoplanet surveys such as TESS. We will also present the first results from the survey: a comprehensive assessment of stellar multiplicity among Kepler exoplanet hosts and the discovery of new close stellar companions around Kepler objects of interest.

  4. Adapting smartphones for low-cost optical medical imaging

    Science.gov (United States)

    Pratavieira, Sebastião.; Vollet-Filho, José D.; Carbinatto, Fernanda M.; Blanco, Kate; Inada, Natalia M.; Bagnato, Vanderlei S.; Kurachi, Cristina

    2015-06-01

    Optical images have been used in several medical situations to improve diagnosis of lesions or to monitor treatments. However, most systems employ expensive scientific (CCD or CMOS) cameras and need computers to display and save the images, usually resulting in a high final cost for the system. Additionally, this sort of apparatus operation usually becomes more complex, requiring more and more specialized technical knowledge from the operator. Currently, the number of people using smartphone-like devices with built-in high quality cameras is increasing, which might allow using such devices as an efficient, lower cost, portable imaging system for medical applications. Thus, we aim to develop methods of adaptation of those devices to optical medical imaging techniques, such as fluorescence. Particularly, smartphones covers were adapted to connect a smartphone-like device to widefield fluorescence imaging systems. These systems were used to detect lesions in different tissues, such as cervix and mouth/throat mucosa, and to monitor ALA-induced protoporphyrin-IX formation for photodynamic treatment of Cervical Intraepithelial Neoplasia. This approach may contribute significantly to low-cost, portable and simple clinical optical imaging collection.

  5. Iterative optical vector-matrix processors (survey of selected achievable operations)

    Science.gov (United States)

    Casasent, D.; Neuman, C.

    1981-01-01

    An iterative optical vector-matrix multiplier with a microprocessor-controlled feedback loop capable of performing a wealth of diverse operations was described. A survey and description of many of its operations demonstrates the versatility and flexibility of this class of optical processor and its use in diverse applications. General operations described include: linear difference and differential equations, linear algebraic equations, matrix equations, matrix inversion, nonlinear matrix equations, deconvolution and eigenvalue and eigenvector computations. Engineering applications being addressed for these different operations and for the IOP are: adaptive phased-array radar, time-dependent system modeling, deconvolution and optimal control.

  6. Novel spectral range expansion method for liquid crystal adaptive optics.

    Science.gov (United States)

    Mu, Quanquan; Cao, Zhaoliang; Hu, Lifa; Liu, Yonggang; Peng, Zenghui; Xuan, Li

    2010-10-11

    Energy loss is a main problem of liquid crystal adaptive optics systems (LC AOSs). It is caused by the polarization dependence and narrow spectral range. The polarization dependence has been avoided by Love and Mu et al. [Appl. Opt. 32, 2222 (1993); Appl. Opt. 47, 4297 (2008)]. In this paper, a novel method was proposed to extend the spectral range of LC AOSs using multiple liquid crystal wavefront correctors (LCWFCs) to improve the energy utilization. Firstly, the chromatism of an LCWFC was measured and analyzed. The calculated results indicate that one LCWFC is only suitable to perform adaptive correction for a narrow waveband; therefore, multiple LCWFCs must be used to achieve a broadband correction. Secondly, based on open-loop control, a novel optical layout consisting of three LCWFCs was proposed to extend the spectral range of LC AOSs and thus achieve correction in the whole waveband of 520-810 nm. Thirdly, a broadband correction experiment was conducted and near diffraction-limited resolution was achieved in the waveband of 520-690 nm. Finally, a 500 m horizontal turbulence correction experiment was performed in the waveband of 520-690 nm. With adaptive correction, the resolution of the optical system was improved significantly and the image of the single fiber was clearly resolved. Furthermore, compared with a sub-waveband system, the system energy was improved. The energy of the whole waveband is equal to the sum of all the sub-wavebands. The experiment results validated our method and indicate that the chromatism in a broad waveband of LC AOSs can be eliminated. And then, the system energy can be improved greatly using the novel method.

  7. Adaptive optical design in surface plasma resonance sensor

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng; ZHONG Jin-gang

    2006-01-01

    A double-prism adaptive optical design in surface plasma resonance (SPR) sensor is proposed,which consists of two identical isosceles right-triangular prisms. One prism is used as a component of Kretschmann configuration,and the other is for regulation of the optical path. When double-prism structure is angle-scanned by an immovable incident ray,the output ray will be always parallel with the incident ray and just has a small displacement with the shift of output point.The output ray can be focused on a fixed photodetector by a convex lens.Thus it can be avoided that a prism and a photodetector rotate by θ and 2θ respectively in conventional angular scanning SPR sensor.This new design reduces the number of the movable components,makes the structure simple and compact,and makes the manipulation convenient.

  8. Aberrations and adaptive optics in super-resolution microscopy.

    Science.gov (United States)

    Booth, Martin; Andrade, Débora; Burke, Daniel; Patton, Brian; Zurauskas, Mantas

    2015-08-01

    As one of the most powerful tools in the biological investigation of cellular structures and dynamic processes, fluorescence microscopy has undergone extraordinary developments in the past decades. The advent of super-resolution techniques has enabled fluorescence microscopy - or rather nanoscopy - to achieve nanoscale resolution in living specimens and unravelled the interior of cells with unprecedented detail. The methods employed in this expanding field of microscopy, however, are especially prone to the detrimental effects of optical aberrations. In this review, we discuss how super-resolution microscopy techniques based upon single-molecule switching, stimulated emission depletion and structured illumination each suffer from aberrations in different ways that are dependent upon intrinsic technical aspects. We discuss the use of adaptive optics as an effective means to overcome this problem.

  9. High Resolution Observations using Adaptive Optics: Achievements and Future Needs

    Indian Academy of Sciences (India)

    K. Sankarasubramanian; T. Rimmele

    2008-03-01

    Over the last few years, several interesting observations were obtained with the help of solar Adaptive Optics (AO). In this paper, few observations made using the solarAOare enlightened and briefly discussed. A list of disadvantages with the current AO system are presented. With telescopes larger than 1.5 m expected during the next decade, there is a need to develop the existing AO technologies for large aperture telescopes. Some aspects of this development are highlighted. Finally, the recent AO developments in India are also presented.

  10. Speckle reconstruction of photometric data observed with adaptive optics

    OpenAIRE

    Puschmann, K. G.; Sailer, M

    2006-01-01

    To achieve the highest spatial resolution for ground-based observations one has to correct for degradations by the Earth’s atmosphere. This can be done by on-line and post-facto techniques. Here we combine observations with Adaptive Optics (AO) and speckle reconstruction. As possible techniques we present two modified versions (methods B and C) of the Göttingen speckle masking code and describe their application to observations of a solar active region obtained with the Swedish 1-m S...

  11. Supernovae and extragalactic astronomy with laser guide star adaptive optics

    CERN Document Server

    Ryder, Stuart D; Kankare, Erkki; Vaisanen, Petri

    2014-01-01

    Using the latest generation of adaptive optics imaging systems together with laser guide stars on 8m-class telescopes, we are finally revealing the previously-hidden population of supernovae in starburst galaxies. Finding these supernovae and measuring the amount of absorption due to dust is crucial to being able to accurately trace the star formation history of our Universe. Our images of the host galaxies are amongst the sharpest ever obtained from the ground, and reveal much about how and why these galaxies are forming massive stars (that become supernovae) at such a prodigious rate.

  12. Self-characterization of linear and nonlinear adaptive optics systems

    Science.gov (United States)

    Hampton, Peter J.; Conan, Rodolphe; Keskin, Onur; Bradley, Colin; Agathoklis, Pan

    2008-01-01

    We present methods used to determine the linear or nonlinear static response and the linear dynamic response of an adaptive optics (AO) system. This AO system consists of a nonlinear microelectromechanical systems deformable mirror (DM), a linear tip-tilt mirror (TTM), a control computer, and a Shack-Hartmann wavefront sensor. The system is modeled using a single-input-single-output structure to determine the one-dimensional transfer function of the dynamic response of the chain of system hardware. An AO system has been shown to be able to characterize its own response without additional instrumentation. Experimentally determined models are given for a TTM and a DM.

  13. An adaptive optics imaging system designed for clinical use.

    Science.gov (United States)

    Zhang, Jie; Yang, Qiang; Saito, Kenichi; Nozato, Koji; Williams, David R; Rossi, Ethan A

    2015-06-01

    Here we demonstrate a new imaging system that addresses several major problems limiting the clinical utility of conventional adaptive optics scanning light ophthalmoscopy (AOSLO), including its small field of view (FOV), reliance on patient fixation for targeting imaging, and substantial post-processing time. We previously showed an efficient image based eye tracking method for real-time optical stabilization and image registration in AOSLO. However, in patients with poor fixation, eye motion causes the FOV to drift substantially, causing this approach to fail. We solve that problem here by tracking eye motion at multiple spatial scales simultaneously by optically and electronically integrating a wide FOV SLO (WFSLO) with an AOSLO. This multi-scale approach, implemented with fast tip/tilt mirrors, has a large stabilization range of ± 5.6°. Our method consists of three stages implemented in parallel: 1) coarse optical stabilization driven by a WFSLO image, 2) fine optical stabilization driven by an AOSLO image, and 3) sub-pixel digital registration of the AOSLO image. We evaluated system performance in normal eyes and diseased eyes with poor fixation. Residual image motion with incremental compensation after each stage was: 1) ~2-3 arc minutes, (arcmin) 2) ~0.5-0.8 arcmin and, 3) ~0.05-0.07 arcmin, for normal eyes. Performance in eyes with poor fixation was: 1) ~3-5 arcmin, 2) ~0.7-1.1 arcmin and 3) ~0.07-0.14 arcmin. We demonstrate that this system is capable of reducing image motion by a factor of ~400, on average. This new optical design provides additional benefits for clinical imaging, including a steering subsystem for AOSLO that can be guided by the WFSLO to target specific regions of interest such as retinal pathology and real-time averaging of registered images to eliminate image post-processing.

  14. Harnessing Adaptive Optics for Space Debris Collision Mitigation

    Science.gov (United States)

    Zovaro, A.; Bennet, F.; Copeland, M.; Rigaut, F.; d'Orgeville, C.; Grosse, D.

    2016-09-01

    Human kind's continued use of space depends upon minimising the build-up of debris in low Earth-orbit (LEO). Preventing collisions between satellites and debris is essential given that a single collision can generate thousands of new debris objects. However, in-orbit manoeuvring of satellites is extremely expensive and shortens their operational life. Adjusting the orbits of debris objects instead of satellites would shift the responsibility of collision avoidance away from satellite operators altogether, thereby offering a superior solution. The Research School of Astronomy and Astrophysics at the Australian National University, partnered with Electro Optic Systems (EOS) Space Systems, Lockheed Martin Corporation and the Space Environment Research Centre (SERC) Limited, are developing the Adaptive Optics Tracking and Pushing (AOTP) system. AOTP will be used to perturb the orbits of debris objects using photon pressure from a 10 kW IR laser beam launched from the 1.8 m telescope at Mount. Stromlo Observatory, Australia. Initial simulations predict that AOTP will be able to displace debris objects 10 cm in size by up to 100 m with several overhead passes. An operational demonstrator is planned for 2019. Turbulence will distort the laser beam as it propagates through the atmosphere, resulting in a lower photon flux on the target and reduced pointing accuracy. To mitigate these effects, adaptive optics (AO) will be used to apply wavefront correction to the beam prior to launch. A unique challenge in designing the AO system arises from the high slew rate needed to track objects in LEO, which in turn requires laser guide star AO for satisfactory wavefront correction. The optical design and results from simulations of estimated performance of AOTP will be presented. In particular, design considerations associated with the high-power laser will be detailed.

  15. Adaptive optics sky coverage modeling for extremely large telescopes.

    Science.gov (United States)

    Clare, Richard M; Ellerbroek, Brent L; Herriot, Glen; Véran, Jean-Pierre

    2006-12-10

    A Monte Carlo sky coverage model for laser guide star adaptive optics systems was proposed by Clare and Ellerbroek [J. Opt. Soc. Am. A 23, 418 (2006)]. We refine the model to include (i) natural guide star (NGS) statistics using published star count models, (ii) noise on the NGS measurements, (iii) the effect of telescope wind shake, (iv) a model for how the Strehl and hence NGS wavefront sensor measurement noise varies across the field, (v) the focus error due to imperfectly tracking the range to the sodium layer, (vi) the mechanical bandwidths of the tip-tilt (TT) stage and deformable mirror actuators, and (vii) temporal filtering of the NGS measurements to balance errors due to noise and servo lag. From this model, we are able to generate a TT error budget for the Thirty Meter Telescope facility narrow-field infrared adaptive optics system (NFIRAOS) and perform several design trade studies. With the current NFIRAOS design, the median TT error at the galactic pole with median seeing is calculated to be 65 nm or 1.8 mas rms.

  16. Photometric Calibration of the Gemini South Adaptive Optics Imager

    Science.gov (United States)

    Stevenson, Sarah Anne; Rodrigo Carrasco Damele, Eleazar; Thomas-Osip, Joanna

    2017-01-01

    The Gemini South Adaptive Optics Imager (GSAOI) is an instrument available on the Gemini South telescope at Cerro Pachon, Chile, utilizing the Gemini Multi-Conjugate Adaptive Optics System (GeMS). In order to allow users to easily perform photometry with this instrument and to monitor any changes in the instrument in the future, we seek to set up a process for performing photometric calibration with standard star observations taken across the time of the instrument’s operation. We construct a Python-based pipeline that includes IRAF wrappers for reduction and combines the AstroPy photutils package and original Python scripts with the IRAF apphot and photcal packages to carry out photometry and linear regression fitting. Using the pipeline, we examine standard star observations made with GSAOI on 68 nights between 2013 and 2015 in order to determine the nightly photometric zero points in the J, H, Kshort, and K bands. This work is based on observations obtained at the Gemini Observatory, processed using the Gemini IRAF and gemini_python packages, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil).

  17. AVES: an adaptive optics visual echelle spectrograph for the VLT

    Science.gov (United States)

    Pasquini, Luca; Delabre, Bernard; Avila, Gerardo; Bonaccini, Domenico

    1998-07-01

    We present the preliminary study of a low cost, high performance spectrograph for the VLT, for observations in the V, R and I bands. This spectrograph is meant for intermediate (R equals 16,000) resolution spectroscopy of faint (sky and/or detector limited) sources, with particular emphasis on the study of solar-type (F-G) stars belonging to the nearest galaxies and to distant (or highly reddened) galactic clusters. The spectrograph is designed to use the adaptive optics (AO) systems at the VLT Telescope. Even if these AO systems will not provide diffraction limited images in the V, R and I bands, the photon concentration will still be above approximately 60% of the flux in an 0.3 arcsecond aperture for typical Paranal conditions. This makes the construction of a compact, cheap and efficient echelle spectrograph possible. AVES will outperform comparable non adaptive optic instruments by more than one magnitude for sky- and/or detector-limited observations, and it will be very suitable for observations in crowded fields.

  18. A New, Adaptable, Optical High-Resolution 3-Axis Sensor

    Directory of Open Access Journals (Sweden)

    Niels Buchhold

    2017-01-01

    Full Text Available This article presents a new optical, multi-functional, high-resolution 3-axis sensor which serves to navigate and can, for example, replace standard joysticks in medical devices such as electric wheelchairs, surgical robots or medical diagnosis devices. A light source, e.g., a laser diode, is affixed to a movable axis and projects a random geometric shape on an image sensor (CMOS or CCD. The downstream microcontroller’s software identifies the geometric shape’s center, distortion and size, and then calculates x, y, and z coordinates, which can be processed in attached devices. Depending on the image sensor in use (e.g., 6.41 megapixels, the 3-axis sensor features a resolution of 1544 digits from right to left and 1038 digits up and down. Through interpolation, these values rise by a factor of 100. A unique feature is the exact reproducibility (deflection to coordinates and its precise ability to return to its neutral position. Moreover, optical signal processing provides a high level of protection against electromagnetic and radio frequency interference. The sensor is adaptive and adjustable to fit a user’s range of motion (stroke and force. This recommendation aims to optimize sensor systems such as joysticks in medical devices in terms of safety, ease of use, and adaptability.

  19. A New, Adaptable, Optical High-Resolution 3-Axis Sensor.

    Science.gov (United States)

    Buchhold, Niels; Baumgartner, Christian

    2017-01-27

    This article presents a new optical, multi-functional, high-resolution 3-axis sensor which serves to navigate and can, for example, replace standard joysticks in medical devices such as electric wheelchairs, surgical robots or medical diagnosis devices. A light source, e.g., a laser diode, is affixed to a movable axis and projects a random geometric shape on an image sensor (CMOS or CCD). The downstream microcontroller's software identifies the geometric shape's center, distortion and size, and then calculates x, y, and z coordinates, which can be processed in attached devices. Depending on the image sensor in use (e.g., 6.41 megapixels), the 3-axis sensor features a resolution of 1544 digits from right to left and 1038 digits up and down. Through interpolation, these values rise by a factor of 100. A unique feature is the exact reproducibility (deflection to coordinates) and its precise ability to return to its neutral position. Moreover, optical signal processing provides a high level of protection against electromagnetic and radio frequency interference. The sensor is adaptive and adjustable to fit a user's range of motion (stroke and force). This recommendation aims to optimize sensor systems such as joysticks in medical devices in terms of safety, ease of use, and adaptability.

  20. A New, Adaptable, Optical High-Resolution 3-Axis Sensor

    Science.gov (United States)

    Buchhold, Niels; Baumgartner, Christian

    2017-01-01

    This article presents a new optical, multi-functional, high-resolution 3-axis sensor which serves to navigate and can, for example, replace standard joysticks in medical devices such as electric wheelchairs, surgical robots or medical diagnosis devices. A light source, e.g., a laser diode, is affixed to a movable axis and projects a random geometric shape on an image sensor (CMOS or CCD). The downstream microcontroller’s software identifies the geometric shape’s center, distortion and size, and then calculates x, y, and z coordinates, which can be processed in attached devices. Depending on the image sensor in use (e.g., 6.41 megapixels), the 3-axis sensor features a resolution of 1544 digits from right to left and 1038 digits up and down. Through interpolation, these values rise by a factor of 100. A unique feature is the exact reproducibility (deflection to coordinates) and its precise ability to return to its neutral position. Moreover, optical signal processing provides a high level of protection against electromagnetic and radio frequency interference. The sensor is adaptive and adjustable to fit a user’s range of motion (stroke and force). This recommendation aims to optimize sensor systems such as joysticks in medical devices in terms of safety, ease of use, and adaptability. PMID:28134824

  1. Overview of deformable mirror technologies for adaptive optics and astronomy

    Science.gov (United States)

    Madec, P.-Y.

    2012-07-01

    From the ardent bucklers used during the Syracuse battle to set fire to Romans’ ships to more contemporary piezoelectric deformable mirrors widely used in astronomy, from very large voice coil deformable mirrors considered in future Extremely Large Telescopes to very small and compact ones embedded in Multi Object Adaptive Optics systems, this paper aims at giving an overview of Deformable Mirror technology for Adaptive Optics and Astronomy. First the main drivers for the design of Deformable Mirrors are recalled, not only related to atmospheric aberration compensation but also to environmental conditions or mechanical constraints. Then the different technologies available today for the manufacturing of Deformable Mirrors will be described, pros and cons analyzed. A review of the Companies and Institutes with capabilities in delivering Deformable Mirrors to astronomers will be presented, as well as lessons learned from the past 25 years of technological development and operation on sky. In conclusion, perspective will be tentatively drawn for what regards the future of Deformable Mirror technology for Astronomy.

  2. Adaptive Optics and Lucky Imager (AOLI): presentation and first light

    CERN Document Server

    Velasco, S; Mackay, C; Oscoz, A; King, D L; Crass, J; Díaz-Sánchez, A; Femenía, B; González-Escalera, V; Labadie, L; López, R L; Garrido, A Pérez; Puga, M; Rodríguez-Ramos, L F; Zuther, J

    2015-01-01

    In this paper we present the Adaptive Optics Lucky Imager (AOLI), a state-of-the-art instrument which makes use of two well proved techniques for extremely high spatial resolution with ground-based telescopes: Lucky Imaging (LI) and Adaptive Optics (AO). AOLI comprises an AO system, including a low order non-linear curvature wavefront sensor together with a 241 actuators deformable mirror, a science array of four 1024x1024 EMCCDs, allowing a 120x120 down to 36x36 arcseconds field of view, a calibration subsystem and a powerful LI software. Thanks to the revolutionary WFS, AOLI shall have the capability of using faint reference stars ({\\it I\\/} $\\sim$ 16.5-17.5), enabling it to be used over a much wider part of the sky than with common Shack-Hartmann AO systems. This instrument saw first light in September 2013 at William Herschel Telescope. Although the instrument was not complete, these commissioning demonstrated its feasibility, obtaining a FWHM for the best PSF of 0.151$\\pm$0.005 arcsec and a plate scale o...

  3. Non-iterative adaptive optical microscopy using wavefront sensing

    Science.gov (United States)

    Tao, X.; Azucena, O.; Kubby, J.

    2016-03-01

    This paper will review the development of wide-field and confocal microscopes with wavefront sensing and adaptive optics for correcting refractive aberrations and compensating scattering when imaging through thick tissues (Drosophila embryos and mouse brain tissue). To make wavefront measurements in biological specimens we have modified the laser guide-star techniques used in astronomy for measuring wavefront aberrations that occur as star light passes through Earth's turbulent atmosphere. Here sodium atoms in Earth's mesosphere, at an altitude of 95 km, are excited to fluoresce at resonance by a high-power sodium laser. The fluorescent light creates a guide-star reference beacon at the top of the atmosphere that can be used for measuring wavefront aberrations that occur as the light passes through the atmosphere. We have developed a related approach for making wavefront measurements in biological specimens using cellular structures labeled with fluorescent proteins as laser guide-stars. An example is a fluorescently labeled centrosome in a fruit fly embryo or neurons and dendrites in mouse brains. Using adaptive optical microscopy we show that the Strehl ratio, the ratio of the peak intensity of an aberrated point source relative to the diffraction limited image, can be improved by an order of magnitude when imaging deeply into live dynamic specimens, enabling near diffraction limited deep tissue imaging.

  4. Emerging Science Capabilities of Modern Adaptive Optics Systems for Exoplanet and Stellar Astrophysics

    Science.gov (United States)

    Jensen-Clem, Rebecca M.

    2017-01-01

    In this dissertation talk, I discuss new science capabilities enabled by the latest generation of adaptive optics systems in the context of faint companion detection and characterization. I address two regimes of adaptive optics: 1) extreme-AO systems that are combined with coronagraphs to detect companions many times fainter than their parent stars; 2) AO systems that are designed to maximize observing efficiency. GPI and SPHERE, two recent extreme-AO high contrast spectro-polarimeters, embody the first regime. These instruments’ design and sensitivity open up the possibility of a new observable for exoplanet characterization: polarized radiation from self-luminous, directly imaged exoplanets in the near-infrared. As part of my dissertation, I demonstrated that GPI can detect linear polarizations on the 1% scale predicted for cloudy, oblate gas giant exoplanets. Future polarimetric surveys will provide the empirical data needed to build the next generation of cloudy atmospheric models, shedding new light on the compositions of exoplanet atmospheres. The second regime of efficiency-optimized adaptive optics is embodied by Robo-AO, a robotic laser guide star AO system newly installed at the Kitt Peak 2.1-m telescope. Capable of observing over 1000 targets per week, Robo-AO enables LGS-AO surveys of unprecedented scale. I exploited Robo-AO’s efficiency to study the origins of stellar angular momentum: by resolving binaries from among the 700+ Pleiades members observed by K2, I related binary separations to K2’s photometrically determined rotation periods. In this talk, I will also describe Robo-AO’s commissioning at the 2.1-m and subsequent pipeline development.

  5. Wavefront sensors and algorithms for adaptive optical systems

    Science.gov (United States)

    Lukin, V. P.; Botygina, N. N.; Emaleev, O. N.; Konyaev, P. A.

    2010-07-01

    The results of recent works related to techniques and algorithms for wave-front (WF) measurement using Shack-Hartmann sensors show their high efficiency in solution of very different problems of applied optics. The goal of this paper was to develop a sensitive Shack-Hartmann sensor with high precision WF measurement capability on the base of modern technology of optical elements making and new efficient methods and computational algorithms of WF reconstruction. The Shack-Hartmann sensors sensitive to small WF aberrations are used for adaptive optical systems, compensating the wave distortions caused by atmospheric turbulence. A high precision Shack-Hartmann WF sensor has been developed on the basis of a low-aperture off-axis diffraction lens array. The device is capable of measuring WF slopes at array sub-apertures of size 640×640 μm with an error not exceeding 4.80 arcsec (0.15 pixel), which corresponds to the standard deviation equal to 0.017λ at the reconstructed WF with wavelength λ . Also the modification of this sensor for adaptive system of solar telescope using extended scenes as tracking objects, such as sunspot, pores, solar granulation and limb, is presented. The software package developed for the proposed WF sensors includes three algorithms of local WF slopes estimation (modified centroids, normalized cross-correlation and fast Fourierdemodulation), as well as three methods of WF reconstruction (modal Zernike polynomials expansion, deformable mirror response functions expansion and phase unwrapping), that can be selected during operation with accordance to the application.

  6. Accounting for anisoplanatic point spread function in deep wide-field adaptive optics images

    CERN Document Server

    Cresci, G; Baker, A J; Lehnert, M D

    2005-01-01

    In this paper we present the approach we have used to determine and account for the anisoplanatic point spread function (PSF) in deep adaptive optics (AO) images for the Survey of a Wide Area with NACO (SWAN) at the ESO VLT. The survey comprises adaptive optics observations in the Ks band totaling ~ 30 arcmin^2, assembled from 42 discrete fields centered on different bright stars suitable for AO guiding. We develop a parametric model of the PSF variations across the field of view in order to build an accurate model PSF for every galaxy detected in each of the fields. We show that this approach is particularly convenient, as it uses only easily available data and makes no uncertain assumptions about the stability of the isoplanatic angle during any given night. The model was tested using simulated galaxy profiles to check its performance in terms of recovering the correct morphological parameters; we find that the results are reliable up to Ks ~ 20.5 (K_AB ~ 22.3) in a typical SWAN field. Finally, the model ob...

  7. Accounting for the anisoplanatic point spread function in deep wide-field adaptive optics images

    Science.gov (United States)

    Cresci, G.; Davies, R. I.; Baker, A. J.; Lehnert, M. D.

    2005-08-01

    In this paper we present the approach we have used to determine and account for the anisoplanatic point spread function (PSF) in deep adaptive optics (AO) images for the Survey of a Wide Area with NACO (SWAN) at the ESO VLT. The survey comprises adaptive optics observations in the Ks band totaling ~30~arcmin^2, assembled from 42 discrete fields centered on different bright stars suitable for AO guiding. We develop a parametric model of the PSF variations across the field of view in order to build an accurate model PSF for every galaxy detected in each of the fields. We show that this approach is particularly convenient, as it uses only easily available data and makes no uncertain assumptions about the stability of the isoplanatic angle during any given night. The model was tested using simulated galaxy profiles to check its performance in terms of recovering the correct morphological parameters; we find that the results are reliable up to Ks ˜ 20.5 (KAB˜22.3) in a typical SWAN field. Finally, the model obtained was used to derive the first results from five SWAN fields, and to obtain the AO morphology of 55 galaxies brighter than Ks = 20. These preliminary results demonstrate the unique power of AO observations to derive the details of faint galaxy morphologies and to study galaxy evolution.

  8. Adaptive Steganography: A survey of Recent Statistical Aware Steganography Techniques

    Directory of Open Access Journals (Sweden)

    Manish Mahajan

    2012-09-01

    Full Text Available Steganography is the science that deals with hiding of secret data in some carrier media which may be image, audio, formatted text or video. The main idea behind this is to conceal the very existence of data. We will be dealing here with image steganography. Many algorithms have been proposed for this purpose in spatial & frequency domain. But in almost all the algorithms it has been noticed that as we embed the secret data in the image the certain characteristics or statistics of the image get disturbed. Based on these disturbed statistics steganalysts can get the reflection about the existence of secret data which they further decode with the help of available steganalytic tools. Steganalysis is a science of attacking the hidden data to get an authorized access. Although steganalysis is not a part of this work but it may be sometimes discussed as a part of literature. Even in steganography we are not purely concerned with spatial or frequency domain rather our main emphasis is on adaptive steganography or model based steganography. Adaptive steganography is not entirely a new branch of steganography rather it is based upon spatial & frequency domain with an additional layer of mathematical model. So here we will be dealing with adaptive steganography which take care about the important characteristics & statistics of the cover image well in advance to the embedding of secret data so that the disturbance of image statistics as mentioned earlier, which attracts the forgery or unauthorized access, can be minimized. In this survey we will analyze the various steganography algorithms which are based upon certain mathematical model or in other words algorithms which come under the category of model based steganography.

  9. Adaptive distributed Kalman filtering with wind estimation for astronomical adaptive optics.

    Science.gov (United States)

    Massioni, Paolo; Gilles, Luc; Ellerbroek, Brent

    2015-12-01

    In the framework of adaptive optics (AO) for astronomy, it is a common assumption to consider the atmospheric turbulent layers as "frozen flows" sliding according to the wind velocity profile. For this reason, having knowledge of such a velocity profile is beneficial in terms of AO control system performance. In this paper we show that it is possible to exploit the phase estimate from a Kalman filter running on an AO system in order to estimate wind velocity. This allows the update of the Kalman filter itself with such knowledge, making it adaptive. We have implemented such an adaptive controller based on the distributed version of the Kalman filter, for a realistic simulation of a multi-conjugate AO system with laser guide stars on a 30 m telescope. Simulation results show that this approach is effective and promising and the additional computational cost with respect to the distributed filter is negligible. Comparisons with a previously published slope detection and ranging wind profiler are made and the impact of turbulence profile quantization is assessed. One of the main findings of the paper is that all flavors of the adaptive distributed Kalman filter are impacted more significantly by turbulence profile quantization than the static minimum mean square estimator which does not incorporate wind profile information.

  10. HI Survey Science with the Canadian Large Adaptive Reflector

    CERN Document Server

    Côté, S; Dewdney, P E

    2002-01-01

    The Canadian Large Adaptive Reflector (CLAR) is a proposed prototype of a new concept for large, filled-aperture radio telescopes. The prototype would have a 300-metre aperture, working up to frequencies of at least 1.4 GHz, and would be equipped with a multi-beam phased array providing a field-of-view of 0.8deg at that frequency. The largest fully-steerable radio telescope in the world, and endowed with a large field-of-view, the CLAR will be uniquely suited for deep spectral imaging over large areas of the sky. Conducted over a period of three to four years, a CLAR Northern-Sky Survey would allow us to simultaneously: survey at arcminute scales the distribution and kinematics of the faint HI in the halo of the Milky Way and High Velocity Clouds; chart the large scale distribution of galaxies in HI out to redshift close to 1; reveal the structure and dynamics of the cosmic web responsible for wide-spread Lyman $\\alpha$ absorption systems; image the signal of the reionization of the Universe over a large area...

  11. Site survey for optimum location of Optical Communication Experimental Facility

    Science.gov (United States)

    1968-01-01

    Site survey was made to determine the optimum location for an Optical Communication Experimental Facility /OCEF/ and to recommend several sites, graded according to preference. A site was desired which could perform two-way laser communication with a spacecraft and laser tracking with a minimum of interruption by weather effects.

  12. Robotic laser adaptive optics imaging of 715 Kepler exoplanet candidates using Robo-AO

    Energy Technology Data Exchange (ETDEWEB)

    Law, Nicholas M.; Ziegler, Carl [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255 (United States); Morton, Tim; Riddle, Reed; Tendulkar, Shriharsh P.; Bui, Khanh; Dekany, Richard G.; Kulkarni, Shrinivas; Punnadi, Sujit [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Baranec, Christoph [Institute for Astronomy, University of Hawai' i at Mānoa, Hilo, HI 96720-2700 (United States); Ravichandran, Ganesh [West Tresper Clarke High School, East Meadow School District, 740 Edgewood Drive, Westbury, NY 11590 (United States); Johnson, John Asher [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Burse, Mahesh P.; Das, H. K.; Ramaprakash, A. N. [Inter-University Centre for Astronomy and Astrophysics, Ganeshkhind, Pune 411007 (India)

    2014-08-10

    The Robo-AO Kepler Planetary Candidate Survey is observing every Kepler planet candidate host star with laser adaptive optics imaging to search for blended nearby stars, which may be physically associated companions and/or responsible for transit false positives. In this paper, we present the results from the 2012 observing season, searching for stars close to 715 Kepler planet candidate hosts. We find 53 companions, 43 of which are new discoveries. We detail the Robo-AO survey data reduction methods including a method of using the large ensemble of target observations as mutual point-spread-function references, along with a new automated companion-detection algorithm designed for large adaptive optics surveys. Our survey is sensitive to objects from ≈0.''15 to 2.''5 separation, with magnitude differences up to Δm ≈ 6. We measure an overall nearby-star probability for Kepler planet candidates of 7.4% ± 1.0%, and calculate the effects of each detected nearby star on the Kepler-measured planetary radius. We discuss several Kepler Objects of Interest (KOIs) of particular interest, including KOI-191 and KOI-1151, which are both multi-planet systems with detected stellar companions whose unusual planetary system architecture might be best explained if they are 'coincident multiple' systems, with several transiting planets shared between the two stars. Finally, we find 98% confidence evidence that short-period giant planets are two to three times more likely than longer-period planets to be found in wide stellar binaries.

  13. Robotic Laser Adaptive Optics Imaging of 715 Kepler Exoplanet Candidates Using Robo-AO

    Science.gov (United States)

    Law, Nicholas M.; Morton, Tim; Baranec, Christoph; Riddle, Reed; Ravichandran, Ganesh; Ziegler, Carl; Johnson, John Asher; Tendulkar, Shriharsh P.; Bui, Khanh; Burse, Mahesh P.; Das, H. K.; Dekany, Richard G.; Kulkarni, Shrinivas; Punnadi, Sujit; Ramaprakash, A. N.

    2014-08-01

    The Robo-AO Kepler Planetary Candidate Survey is observing every Kepler planet candidate host star with laser adaptive optics imaging to search for blended nearby stars, which may be physically associated companions and/or responsible for transit false positives. In this paper, we present the results from the 2012 observing season, searching for stars close to 715 Kepler planet candidate hosts. We find 53 companions, 43 of which are new discoveries. We detail the Robo-AO survey data reduction methods including a method of using the large ensemble of target observations as mutual point-spread-function references, along with a new automated companion-detection algorithm designed for large adaptive optics surveys. Our survey is sensitive to objects from ≈0.''15 to 2.''5 separation, with magnitude differences up to Δm ≈ 6. We measure an overall nearby-star probability for Kepler planet candidates of 7.4% ± 1.0%, and calculate the effects of each detected nearby star on the Kepler-measured planetary radius. We discuss several Kepler Objects of Interest (KOIs) of particular interest, including KOI-191 and KOI-1151, which are both multi-planet systems with detected stellar companions whose unusual planetary system architecture might be best explained if they are "coincident multiple" systems, with several transiting planets shared between the two stars. Finally, we find 98% confidence evidence that short-period giant planets are two to three times more likely than longer-period planets to be found in wide stellar binaries.

  14. Postural adaptations to repeated optic flow stimulation in older adults.

    Science.gov (United States)

    O'Connor, Kathryn W; Loughlin, Patrick J; Redfern, Mark S; Sparto, Patrick J

    2008-10-01

    The purpose of this study is to understand the processes of adaptation (changes in within-trial postural responses) and habituation (reductions in between-trial postural responses) to visual cues in older and young adults. Of particular interest were responses to sudden increases in optic flow magnitude. The postural sway of 25 healthy young adults and 24 healthy older adults was measured while subjects viewed anterior-posterior 0.4 Hz sinusoidal optic flow for 45 s. Three trials for each of three conditions were performed: (1) constant 12 cm optic flow amplitude (24 cm peak-to-peak), (2) constant 4 cm amplitude (8 cm p-t-p), and (3) a transition in amplitude from 4 to 12 cm. The average power of head sway velocity (P(vel)) was calculated for consecutive 5s intervals during the trial to examine the changes in sway within and between trials. A mixed factor repeated measures ANOVA was performed to examine the effects of subject Group, Trial, and Interval on the P(vel). P(vel) was greater in older adults in all conditions (phabituation. P(vel) of the older adults decreased significantly between all 3 trials, but decreased only between Trials 1 and 2 in young adults. While the responses of the young adults to the transition in optic flow from 4 to 12 cm did not significantly change, older adults had an increase in P(vel) following the transition, ranging from 6.5 dB for the first trial to 3.4 dB for the third trial. These results show that older adults can habituate to repeated visual perturbation exposures; however, this habituation requires a greater number of exposures than young adults. This suggests aging impacts the ability to quickly modify the relative weighting of the sensory feedback for postural stabilization.

  15. Closed-loop optical stabilization and digital image registration in adaptive optics scanning light ophthalmoscopy.

    Science.gov (United States)

    Yang, Qiang; Zhang, Jie; Nozato, Koji; Saito, Kenichi; Williams, David R; Roorda, Austin; Rossi, Ethan A

    2014-09-01

    Eye motion is a major impediment to the efficient acquisition of high resolution retinal images with the adaptive optics (AO) scanning light ophthalmoscope (AOSLO). Here we demonstrate a solution to this problem by implementing both optical stabilization and digital image registration in an AOSLO. We replaced the slow scanning mirror with a two-axis tip/tilt mirror for the dual functions of slow scanning and optical stabilization. Closed-loop optical stabilization reduced the amplitude of eye-movement related-image motion by a factor of 10-15. The residual RMS error after optical stabilization alone was on the order of the size of foveal cones: ~1.66-2.56 μm or ~0.34-0.53 arcmin with typical fixational eye motion for normal observers. The full implementation, with real-time digital image registration, corrected the residual eye motion after optical stabilization with an accuracy of ~0.20-0.25 μm or ~0.04-0.05 arcmin RMS, which to our knowledge is more accurate than any method previously reported.

  16. Statistical learning methods for aero-optic wavefront prediction and adaptive-optic latency compensation

    Science.gov (United States)

    Burns, W. Robert

    Since the early 1970's research in airborne laser systems has been the subject of continued interest. Airborne laser applications depend on being able to propagate a near diffraction-limited laser beam from an airborne platform. Turbulent air flowing over the aircraft produces density fluctuations through which the beam must propagate. Because the index of refraction of the air is directly related to the density, the turbulent flow imposes aberrations on the beam passing through it. This problem is referred to as Aero-Optics. Aero-Optics is recognized as a major technical issue that needs to be solved before airborne optical systems can become routinely fielded. This dissertation research specifically addresses an approach to mitigating the deleterious effects imposed on an airborne optical system by aero-optics. A promising technology is adaptive optics: a feedback control method that measures optical aberrations and imprints the conjugate aberrations onto an outgoing beam. The challenge is that it is a computationally-difficult problem, since aero-optic disturbances are on the order of kilohertz for practical applications. High control loop frequencies and high disturbance frequencies mean that adaptive-optic systems are sensitive to latency in sensors, mirrors, amplifiers, and computation. These latencies build up to result in a dramatic reduction in the system's effective bandwidth. This work presents two variations of an algorithm that uses model reduction and data-driven predictors to estimate the evolution of measured wavefronts over a short temporal horizon and thus compensate for feedback latency. The efficacy of the two methods are compared in this research, and evaluated against similar algorithms that have been previously developed. The best version achieved over 75% disturbance rejection in simulation in the most optically active flow region in the wake of a turret, considerably outperforming conventional approaches. The algorithm is shown to be

  17. Compact MEMS-based Adaptive Optics Optical Coherence Tomography for Clinical Use

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D; Olivier, S; Jones, S; Zawadzki, R; Evans, J; Choi, S; Werner, J

    2008-02-04

    We describe a compact MEMS-based adaptive optics (AO) optical coherence tomography system with improved AO performance and ease of clinical use. A typical AO system consists of a Shack-Hartmann wavefront sensor and a deformable mirror that measures and corrects the ocular and system aberrations. Because of the limitation on the current deformable mirror technologies, the amount of real-time ocular-aberration compensation is restricted and small in the previous AO-OCT instruments. In this instrument, we proposed to add an optical apparatus to correct the spectacle aberrations of the patients such as myopia, hyperopia and astigmatism. This eliminated the tedious process of the trial lenses in clinical imaging. Different amount of spectacle aberration compensation was achieved by motorized stages and automated with the AO computer for ease of clinical use. In addition, the compact AO-OCT was optimized to have minimum system aberrations to reduce AO registration errors and improve AO performance.

  18. Binary stars observed with adaptive optics at the starfire optical range

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, Jack D. [Air Force Research Laboratory, Directed Energy Directorate, RDSAM, 3550 Aberdeen Avenue SE, Kirtland AFB, NM 87117-5776 (United States)

    2014-03-01

    In reviewing observations taken of binary stars used as calibration objects for non-astronomical purposes with adaptive optics on the 3.5 m Starfire Optical Range telescope over the past 2 years, one-fifth of them were found to be off-orbit. In order to understand such a high number of discrepant position angles and separations, all previous observations in the Washington Double Star Catalog for these rogue binaries were obtained from the Naval Observatory. Adding our observations to these yields new orbits for all, resolving the discrepancies. We have detected both components of γ Gem for the first time, and we have shown that 7 Cam is an optical pair, not physically bound.

  19. Kalman filtering to suppress spurious signals in Adaptive Optics control

    Energy Technology Data Exchange (ETDEWEB)

    Poyneer, L; Veran, J P

    2010-03-29

    In many scenarios, an Adaptive Optics (AO) control system operates in the presence of temporally non-white noise. We use a Kalman filter with a state space formulation that allows suppression of this colored noise, hence improving residual error over the case where the noise is assumed to be white. We demonstrate the effectiveness of this new filter in the case of the estimated Gemini Planet Imager tip-tilt environment, where there are both common-path and non-common path vibrations. We discuss how this same framework can also be used to suppress spatial aliasing during predictive wavefront control assuming frozen flow in a low-order AO system without a spatially filtered wavefront sensor, and present experimental measurements from Altair that clearly reveal these aliased components.

  20. `imaka - a ground-layer adaptive optics system on Maunakea

    CERN Document Server

    Chun, Mark; Toomey, Douglas; Lu, Jessica; Service, Max; Baranec, Christoph; Thibault, Simon; Brousseau, Denis; Hayano, Yutaka; Oya, Shin; Santi, Shane; Kingery, Christopher; Loss, Keith; Gardiner, John; Steele, Brad

    2016-01-01

    We present the integration status for `imaka, the ground-layer adaptive optics (GLAO) system on the University of Hawaii 2.2-meter telescope on Maunakea, Hawaii. This wide-field GLAO pathfinder system exploits Maunakea's highly confined ground layer and weak free-atmosphere to push the corrected field of view to ~1/3 of a degree, an areal field approaching an order of magnitude larger than any existing or planned GLAO system, with a FWHM ~ 0.33 arcseconds in the visible and near infrared. We discuss the unique design aspects of the instrument, the driving science cases and how they impact the system, and how we will demonstrate these cases on the sky.

  1. Adaptive optics imaging of low and intermediate redshift quasars

    CERN Document Server

    Márquez, I; Theodore, B; Bremer, M; Monnet, G; Beuzit, J L

    2001-01-01

    We present the results of adaptive-optics imaging in the H and K bands of 12 low and intermediate redshift (z15.0) themselves as reference for the correction, have typical spatial resolution of FWHM~0.3 arcsec before deconvolution. The deconvolved H-band image of PG1700+514 has a spatial resolution of 0.16 arcsec and reveals a wealth of details on the companion and the host-galaxy. Four out of the twelve quasars have close companions and obvious signs of interactions. The two-dimensional images of three of the host-galaxies unambiguously reveal bars and spiral arms. The morphology of the other objects are difficult to determine from one dimensional surface brightness profile and deeper images are needed. Analysis of mocked data shows that elliptical galaxies are always recognized as such, whereas disk hosts can be missed for small disk scale lengths and large QSO contributions.

  2. Development of large aperture elements for active and adaptive optics

    Directory of Open Access Journals (Sweden)

    Stranakova E.

    2013-05-01

    Full Text Available Large-aperture elements for laser active and adaptive optics are investigated in collaboration within IOP AcSci CR, FEng CTU and 5M. A bimorph deformable mirror for high-power lasers based on a lightweight structure with a composite core is currently in development. In order to realize a sufficiently large working aperture we are using new technologies for production of core, bimorph actuator and DM reflector. Detailed simulation of components and structure is validated by measurement and testing. A research of DM actuation and response of a complicated mirror structure needed for an accurate control of a deformation is performed. Testing of samples and subscale measurements are currently performed, measurement of a complete structure is in preparation.

  3. Performance of the Keck Observatory adaptive optics system

    Energy Technology Data Exchange (ETDEWEB)

    van Dam, M A; Mignant, D L; Macintosh, B A

    2004-01-19

    In this paper, the adaptive optics (AO) system at the W.M. Keck Observatory is characterized. The authors calculate the error budget of the Keck AO system operating in natural guide star mode with a near infrared imaging camera. By modeling the control loops and recording residual centroids, the measurement noise and band-width errors are obtained. The error budget is consistent with the images obtained. Results of sky performance tests are presented: the AO system is shown to deliver images with average Strehl ratios of up to 0.37 at 1.58 {micro}m using a bright guide star and 0.19 for a magnitude 12 star.

  4. MICADO: the E-ELT Adaptive Optics Imaging Camera

    CERN Document Server

    Davies, R

    2010-01-01

    MICADO is the adaptive optics imaging camera for the E-ELT. It has been designed and optimised to be mounted to the LGS-MCAO system MAORY, and will provide diffraction limited imaging over a wide (about 1 arcmin) field of view. For initial operations, it can also be used with its own simpler AO module that provides on-axis diffraction limited performance using natural guide stars. We discuss the instrument's key capabilities and expected performance, and show how the science drivers have shaped its design. We outline the technical concept, from the opto-mechanical design to operations and data processing. We describe the AO module, summarise the instrument performance, and indicate some possible future developments.

  5. Adaptive fiber optics collimator based on flexible hinges.

    Science.gov (United States)

    Zhi, Dong; Ma, Yanxing; Ma, Pengfei; Si, Lei; Wang, Xiaolin; Zhou, Pu

    2014-08-20

    In this manuscript, we present a new design for an adaptive fiber optics collimator (AFOC) based on flexible hinges by using piezoelectric stacks actuators for X-Y displacement. Different from traditional AFOC, the new structure is based on flexible hinges to drive the fiber end cap instead of naked fiber. We fabricated a real AFOC based on flexible hinges, and the end cap's deviation and resonance frequency of the device were measured. Experimental results show that this new AFOC can provide fast control of tip-tilt deviation of the laser beam emitting from the end cap. As a result, the fiber end cap can support much higher power than naked fiber, which makes the new structure ideal for tip-tilt controlling in a high-power fiber laser system.

  6. Kalman filtering to suppress spurious signals in Adaptive Optics control

    Energy Technology Data Exchange (ETDEWEB)

    Poyneer, L; Veran, J P

    2010-03-29

    In many scenarios, an Adaptive Optics (AO) control system operates in the presence of temporally non-white noise. We use a Kalman filter with a state space formulation that allows suppression of this colored noise, hence improving residual error over the case where the noise is assumed to be white. We demonstrate the effectiveness of this new filter in the case of the estimated Gemini Planet Imager tip-tilt environment, where there are both common-path and non-common path vibrations. We discuss how this same framework can also be used to suppress spatial aliasing during predictive wavefront control assuming frozen flow in a low-order AO system without a spatially filtered wavefront sensor, and present experimental measurements from Altair that clearly reveal these aliased components.

  7. Atmospheric refractivity effects on mid-infrared ELT adaptive optics

    CERN Document Server

    Kendrew, S; Mathar, R J; Stuik, R; Hippler, S; Brandl, B

    2008-01-01

    We discuss the effect of atmospheric dispersion on the performance of a mid-infrared adaptive optics assisted instrument on an extremely large telescope (ELT). Dispersion and atmospheric chromaticity is generally considered to be negligible in this wavelength regime. It is shown here, however, that with the much-reduced diffraction limit size on an ELT and the need for diffraction-limited performance, refractivity phenomena should be carefully considered in the design and operation of such an instrument. We include an overview of the theory of refractivity, and the influence of infrared resonances caused by the presence of water vapour and other constituents in the atmosphere. `Traditional' atmospheric dispersion is likely to cause a loss of Strehl only at the shortest wavelengths (L-band). A more likely source of error is the difference in wavelengths at which the wavefront is sensed and corrected, leading to pointing offsets between wavefront sensor and science instrument that evolve with time over a long e...

  8. High-redshift quasar host galaxies with adaptive optics

    CERN Document Server

    Kuhlbrodt, B; Wisotzki, L; Jahnke, K

    2005-01-01

    We present K band adaptive optics observations of three high-redshift (z ~ 2.2) high-luminosity quasars, all of which were studied for the first time. We also bserved several point spread function (PSF) calibrators, non-simultaneously because of the small field of view. The significant temporal PSF variations on timescales of minutes inhibited a straightforward scaled PSF removal from the quasar images. Characterising the degree of PSF concentration by the radii encircling 20% and 80% of the total flux, respectively, we found that even under very different observing conditions the r20 vs. r80 relation varied coherently between individual short exposure images, delineating a well-defined relation for point sources. Placing the quasar images on this relation, we see indications that all three objects were resolved. We designed a procedure to estimate the significance of this result, and to estimate host galaxy parameters, by reproducing the statistical distribution of the individual short exposure images. We fi...

  9. Enhancing stellar spectroscopy with extreme adaptive optics and photonics

    CERN Document Server

    Jovanovic, Nemanja; Cvetojevic, Nick; Guyon, Olivier; Martinache, Frantz

    2016-01-01

    Extreme adaptive optics systems are now in operation across the globe. These systems, capable of high order wavefront correction, deliver Strehl ratios of 90% in the near-infrared. Originally intended for the direct imaging of exoplanets, these systems are often equipped with advanced coronagraphs that suppress the on-axis-star, interferometers to calibrate wavefront errors, and low order wavefront sensors to stabilize any tip/tilt residuals to a degree never seen before. Such systems are well positioned to facilitate the detailed spectroscopic characterization of faint substellar companions at small angular separations from the host star. Additionally, the increased light concentration of the point-spread function and the unprecedented stability create opportunities in other fields of astronomy as well, including spectroscopy. With such Strehl ratios, efficient injection into single-mode fibers or photonic lanterns becomes possible. With diffraction-limited components feeding the instrument, calibrating a sp...

  10. Synthetic Modeling of Astronomical Closed Loop Adaptive Optics

    CERN Document Server

    Jolissaint, Laurent

    2010-01-01

    We present an analytical model of a single natural guide star astronomical adaptive optics system, in closed loop mode. The model is used to simulate the long exposure system point spread function, using the spatial frequency (or Fourier) approach, and complement an initial open loop model. Applications range from system design, science case analysis and AO data reduction. All the classical phase errors have been included: deformable mirror fitting error, wavefront sensor spatial aliasing, wavefront sensor noise, and the correlated anisoplanatic and servo-lag error. The model includes the deformable mirror spatial transfer function, and the actuator array geometry can be different from the wavefront sensor lenslet array geometry. We also include the dispersion between the sensing and the correction wavelengths. Illustrative examples are given at the end of the paper.

  11. WISE An Adaptative Simulation of the LHC Optics

    CERN Document Server

    Hagen, P; Koutchouk, Jean-Pierre; Risselada, Thys; Sanfilippo, S; Todesco, E; Wildner, E

    2006-01-01

    The beam dynamics in LHC requires a tight control of the field quality and geometry of the magnets. As the production advances, decisions have to be made on the acceptance of possible imperfections. To ease decision making, an adaptative model of the LHC optics has been built, based on the information available on the day (e.g. magnetic measurements at warm or cold, magnet allocation to machine slots) as well as on statistical evaluations for the missing information (e.g. magnets yet to be built, measured, or for non-allocated slots). The uncertainties are included: relative and absolute measurement errors, warm-to-cold correlations for the fraction of magnets not measured at cold, hysteresis and power supply accuracy. The pre-processor WISE generates instances of the LHC field errors for the MAD-X program, with the possibility of selecting various sources. We present an application to estimate the expected beta-beating.

  12. Chromatic effects of the atmosphere on astronomical adaptive optics.

    Science.gov (United States)

    Devaney, Nicholas; Goncharov, Alexander V; Dainty, J Christopher

    2008-03-10

    The atmosphere introduces chromatic errors that may limit the performance of adaptive optics (AO) systems on large telescopes. Various aspects of this problem have been considered in the literature over the past two decades. It is necessary to revisit this problem in order to examine the effect on currently planned systems, including very high-order AO on current 8-10 m class telescopes and on future 30-42 m extremely large telescopes. We review the literature on chromatic effects and combine an analysis of all effects in one place. We examine implications for AO and point out some effects that should be taken into account in the design of future systems. In particular we show that attention should be paid to chromatic pupil shifts, which may arise in components such as atmospheric dispersion compensators.

  13. Adaptive optics retinal imaging in the living mouse eye.

    Science.gov (United States)

    Geng, Ying; Dubra, Alfredo; Yin, Lu; Merigan, William H; Sharma, Robin; Libby, Richard T; Williams, David R

    2012-04-01

    Correction of the eye's monochromatic aberrations using adaptive optics (AO) can improve the resolution of in vivo mouse retinal images [Biss et al., Opt. Lett. 32(6), 659 (2007) and Alt et al., Proc. SPIE 7550, 755019 (2010)], but previous attempts have been limited by poor spot quality in the Shack-Hartmann wavefront sensor (SHWS). Recent advances in mouse eye wavefront sensing using an adjustable focus beacon with an annular beam profile have improved the wavefront sensor spot quality [Geng et al., Biomed. Opt. Express 2(4), 717 (2011)], and we have incorporated them into a fluorescence adaptive optics scanning laser ophthalmoscope (AOSLO). The performance of the instrument was tested on the living mouse eye, and images of multiple retinal structures, including the photoreceptor mosaic, nerve fiber bundles, fine capillaries and fluorescently labeled ganglion cells were obtained. The in vivo transverse and axial resolutions of the fluorescence channel of the AOSLO were estimated from the full width half maximum (FWHM) of the line and point spread functions (LSF and PSF), and were found to be better than 0.79 μm ± 0.03 μm (STD)(45% wider than the diffraction limit) and 10.8 μm ± 0.7 μm (STD)(two times the diffraction limit), respectively. The axial positional accuracy was estimated to be 0.36 μm. This resolution and positional accuracy has allowed us to classify many ganglion cell types, such as bistratified ganglion cells, in vivo.

  14. 4th International Workshop on Adaptive Optics for Industry and Medicine

    CERN Document Server

    Wittrock, Ulrich

    2005-01-01

    This book treats the development and application of adaptive optics for industry and medicine. The contributions describe recently developed components for adaptive-optics systems such as deformable mirrors, wavefront sensors, and mirror drivers as well as complete adaptive optical systems and their applications in industry and medicine. Applications range from laser-beam forming and adaptive aberration correction for high-power lasers to retinal imaging in ophthalmology. The contributions are based on presentations made at the 4th International Workshop on Adaptive Optics in Industry and Medicine which took place in Münster, Germany, in October 2003. This highly successful series of workshops on adaptive optics started in 1997 and continues with the 5th workshop in Beijing in 2005.

  15. ESO adaptive optics facility progress and first laboratory test results

    Science.gov (United States)

    Arsenault, Robin; Madec, Pierre-Yves; Paufique, Jérome; La Penna, Paolo; Stroebele, Stefan; Vernet, Elise; Pirard, Jean-Francois; Hackenberg, Wolfgang; Kuntschner, Harald; Kolb, Johann; Muller, Nicolas; Garcia-Rissmann, Aurea; Le Louarn, Miska; Amico, Paola; Hubin, Norbert; Lizon, Jean-Louis; Ridings, Rob; Haguenauer, Pierre; Abad, Jose A.; Fischer, Gerhard; Heinz, Volker; Kiekebusch, Mario; Argomedo, Javier; Conzelmann, Ralf; Tordo, Sebastien; Donaldson, Rob; Soenke, Christian; Duhoux, Philippe; Fedrigo, Enrico; Delabre, Bernard; Jost, Andrea; Duchateau, Michel; Downing, Mark; Reyes Moreno, Javier; Manescau, Antonio; Bonaccini Calia, Domenico; Quattri, Marco; Dupuy, Christophe; Guidolin, Ivan M.; Comin, Mauro; Guzman, Ronald; Buzzoni, Bernard; Quentin, Jutta; Lewis, Steffan; Jolley, Paul; Kraus, Max; Pfrommer, Thomas; Biasi, Roberto; Gallieni, Daniele; Stuik, Remko; Kaenders, Wilhelm; Ernstberger, Bernhard; Friedenauer, Axel

    2014-07-01

    The Adaptive Optics Facility project is completing the integration of its systems at ESO Headquarters in Garching. The main test bench ASSIST and the 2nd Generation M2-Unit (hosting the Deformable Secondary Mirror) have been granted acceptance late 2012. The DSM has undergone a series of tests on ASSIST in 2013 which have validated its optical performance and launched the System Test Phase of the AOF. This has been followed by the performance evaluation of the GRAAL natural guide star mode on-axis and will continue in 2014 with its Ground Layer AO mode. The GALACSI module (for MUSE) Wide-Field-Mode (GLAO) and the more challenging Narrow-Field-Mode (LTAO) will then be tested. The AOF has also taken delivery of the second scientific thin shell mirror and the first 22 Watt Sodium laser Unit. We will report on the system tests status, the performances evaluated on the ASSIST bench and advancement of the 4Laser Guide Star Facility. We will also present the near future plans for commissioning on the telescope and some considerations on tools to ensure an efficient operation of the Facility in Paranal.

  16. A Bayesian regularized artificial neural network for adaptive optics forecasting

    Science.gov (United States)

    Sun, Zhi; Chen, Ying; Li, Xinyang; Qin, Xiaolin; Wang, Huiyong

    2017-01-01

    Real-time adaptive optics is a technology for enhancing the resolution of ground-based optical telescopes and overcoming the disturbance of atmospheric turbulence. The performance of the system is limited by delay errors induced by the servo system and photoelectrons noise of wavefront sensor. In order to cut these delay errors, this paper proposes a novel model to forecast the future control voltages of the deformable mirror. The predictive model is constructed by a multi-layered back propagation network with Bayesian regularization (BRBP). For the purpose of parallel computation and less disturbance, we adopt a number of sub-BP neural networks to substitute the whole network. The Bayesian regularized network assigns a probability to the network weights, allowing the network to automatically and optimally penalize excessively complex models. The simulation results show that the BRBP introduces smaller mean absolute percentage error (MAPE) and mean square errors (MSE) than other typical algorithms. Meanwhile, real data analysis results show that the BRBP model has strong generalization capability and parallelism.

  17. Advanced capabilities of the multimodal adaptive optics imager

    Science.gov (United States)

    Hammer, Daniel X.; Ferguson, R. D.; Mujat, Mircea; Biss, David P.; Iftimia, Nicusor V.; Patel, Ankit H.; Plumb, Emily; Campbell, Melanie; Norris, Jennifer L.; Dubra, Alfredo; Chui, Toco Y. P.; Akula, James D.; Fulton, Anne B.

    2011-03-01

    We recently developed several versions of a multimodal adaptive optics (AO) retinal imager, which includes highresolution scanning laser ophthalmoscopy (SLO) and Fourier domain optical coherence tomography (FDOCT) imaging channels as well as an auxiliary wide-field line scanning ophthalmoscope (LSO). Some versions have also been equipped with a fluorescence channel and a retinal tracker. We describe the performance of three key features of the multimodal AO system including: simultaneous SLO/OCT imaging, which allows SLO/OCT co-registration; a small animal imaging port, which adjusts the beam diameter at the pupil from 7.5 to 2.5 mm for use with small animals ubiquitous in biological research or for extended depth-of-focus imaging in humans; and slow scan Doppler flowmetry imaging using the wide field auxiliary LSO imaging channel. The systems are currently deployed in several ophthalmology clinics and research laboratories and several investigations have commenced on patients with a variety of retinal diseases and animals in vision research.

  18. The Inner Kiloparsec of Mrk 273 with Keck Adaptive Optics

    CERN Document Server

    Vivian, U; Sanders, David; Max, Claire; Armus, Lee; Iwasawa, Kazushi; Evans, Aaron; Kewley, Lisa; Fazio, Giovanni

    2013-01-01

    There is X-ray, optical, and mid-infrared imaging and spectroscopic evidence that the late-stage ultraluminous infrared galaxy merger Mrk 273 hosts a powerful active galactic nucleus (AGN). However, the exact location of the AGN and the nature of the nuclei have been difficult to determine due to dust obscuration and the limited wavelength coverage of available high-resolution data. Here we present near-infrared integral-field spectra and images of the nuclear region of Mrk 273 taken with OSIRIS and NIRC2 on the Keck II Telescope with laser guide star adaptive optics. We observe three spatially resolved components, and analyze the local molecular and ionized gas emission lines and their kinematics. We confirm the presence of the hard X-ray AGN in the southwest nucleus. In the north nucleus, we find a strongly rotating gas disk whose kinematics indicate a central black hole of mass 1.04 +/- 0.1 x 10^9 Msun. The H2 emission line shows an increase in velocity dispersion along the minor axis in both directions, a...

  19. Adaptive optics ophthalmologic systems using dual deformable mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Jones, S; Olivier, S; Chen, D; Sadda, S; Joeres, S; Zawadzki, R; Werner, J S; Miller, D

    2007-02-01

    Adaptive Optics (AO) have been increasingly combined with a variety of ophthalmic instruments over the last decade to provide cellular-level, in-vivo images of the eye. The use of MEMS deformable mirrors in these instruments has recently been demonstrated to reduce system size and cost while improving performance. However, currently available MEMS mirrors lack the required range of motion for correcting large ocular aberrations, such as defocus and astigmatism. In order to address this problem, we have developed an AO system architecture that uses two deformable mirrors, in a woofer/tweeter arrangement, with a bimorph mirror as the woofer and a MEMS mirror as the tweeter. This setup provides several advantages, including extended aberration correction range, due to the large stroke of the bimorph mirror, high order aberration correction using the MEMS mirror, and additionally, the ability to ''focus'' through the retina. This AO system architecture is currently being used in four instruments, including an Optical Coherence Tomography (OCT) system and a retinal flood-illuminated imaging system at the UC Davis Medical Center, a Scanning Laser Ophthalmoscope (SLO) at the Doheny Eye Institute, and an OCT system at Indiana University. The design, operation and evaluation of this type of AO system architecture will be presented.

  20. Adaptive optics scanning laser ophthalmoscope imaging: technology update.

    Science.gov (United States)

    Merino, David; Loza-Alvarez, Pablo

    2016-01-01

    Adaptive optics (AO) retinal imaging has become very popular in the past few years, especially within the ophthalmic research community. Several different retinal techniques, such as fundus imaging cameras or optical coherence tomography systems, have been coupled with AO in order to produce impressive images showing individual cell mosaics over different layers of the in vivo human retina. The combination of AO with scanning laser ophthalmoscopy has been extensively used to generate impressive images of the human retina with unprecedented resolution, showing individual photoreceptor cells, retinal pigment epithelium cells, as well as microscopic capillary vessels, or the nerve fiber layer. Over the past few years, the technique has evolved to develop several different applications not only in the clinic but also in different animal models, thanks to technological developments in the field. These developments have specific applications to different fields of investigation, which are not limited to the study of retinal diseases but also to the understanding of the retinal function and vision science. This review is an attempt to summarize these developments in an understandable and brief manner in order to guide the reader into the possibilities that AO scanning laser ophthalmoscopy offers, as well as its limitations, which should be taken into account when planning on using it.

  1. Adaptive optics scanning laser ophthalmoscope imaging: technology update

    Directory of Open Access Journals (Sweden)

    Merino D

    2016-04-01

    Full Text Available David Merino, Pablo Loza-Alvarez The Institute of Photonic Sciences (ICFO, The Barcelona Institute of Science and Technology, Castelldefels, Barcelona, Spain Abstract: Adaptive optics (AO retinal imaging has become very popular in the past few years, especially within the ophthalmic research community. Several different retinal techniques, such as fundus imaging cameras or optical coherence tomography systems, have been coupled with AO in order to produce impressive images showing individual cell mosaics over different layers of the in vivo human retina. The combination of AO with scanning laser ophthalmoscopy has been extensively used to generate impressive images of the human retina with unprecedented resolution, showing individual photoreceptor cells, retinal pigment epithelium cells, as well as microscopic capillary vessels, or the nerve fiber layer. Over the past few years, the technique has evolved to develop several different applications not only in the clinic but also in different animal models, thanks to technological developments in the field. These developments have specific applications to different fields of investigation, which are not limited to the study of retinal diseases but also to the understanding of the retinal function and vision science. This review is an attempt to summarize these developments in an understandable and brief manner in order to guide the reader into the possibilities that AO scanning laser ophthalmoscopy offers, as well as its limitations, which should be taken into account when planning on using it. Keywords: high-resolution, in vivo retinal imaging, AOSLO

  2. Precision targeting with a tracking adaptive optics scanning laser ophthalmoscope

    Science.gov (United States)

    Hammer, Daniel X.; Ferguson, R. Daniel; Bigelow, Chad E.; Iftimia, Nicusor V.; Ustun, Teoman E.; Noojin, Gary D.; Stolarski, David J.; Hodnett, Harvey M.; Imholte, Michelle L.; Kumru, Semih S.; McCall, Michelle N.; Toth, Cynthia A.; Rockwell, Benjamin A.

    2006-02-01

    Precise targeting of retinal structures including retinal pigment epithelial cells, feeder vessels, ganglion cells, photoreceptors, and other cells important for light transduction may enable earlier disease intervention with laser therapies and advanced methods for vision studies. A novel imaging system based upon scanning laser ophthalmoscopy (SLO) with adaptive optics (AO) and active image stabilization was designed, developed, and tested in humans and animals. An additional port allows delivery of aberration-corrected therapeutic/stimulus laser sources. The system design includes simultaneous presentation of non-AO, wide-field (~40 deg) and AO, high-magnification (1-2 deg) retinal scans easily positioned anywhere on the retina in a drag-and-drop manner. The AO optical design achieves an error of third generation retinal tracking system achieves a bandwidth of greater than 1 kHz allowing acquisition of stabilized AO images with an accuracy of ~10 μm. Normal adult human volunteers and animals with previously-placed lesions (cynomolgus monkeys) were tested to optimize the tracking instrumentation and to characterize AO imaging performance. Ultrafast laser pulses were delivered to monkeys to characterize the ability to precisely place lesions and stimulus beams. Other advanced features such as real-time image averaging, automatic highresolution mosaic generation, and automatic blink detection and tracking re-lock were also tested. The system has the potential to become an important tool to clinicians and researchers for early detection and treatment of retinal diseases.

  3. A review of astronomical science with visible light adaptive optics

    Science.gov (United States)

    Close, Laird M.

    2016-07-01

    We review astronomical results in the visible (λRobo-AO system (Baranec, et al. 2016) on the robotic Palomar D=1.5 m telescope (currently relocated to the Kitt Peak 1.8m; Salama et al. 2016). Robo-AO uniquely offers the ability to target >15 objects/hr, which has enabled large (>3000 discrete targets) companion star surveys and has resulted in 23 refereed science publications. The most productive large telescope visible AO system is the D=6.5m Magellan telescope AO system (MagAO). MagAO is an advanced Adaptive Secondary Mirror (ASM) AO system at the Magellan 6.5m in Chile (Morzinski et al. 2016). This ASM secondary has 585 actuators with 10m) diameter telescopes in the infrared.

  4. Satellite Imaging with Adaptive Optics on a 1 M Telescope

    Science.gov (United States)

    Bennet, F.; Price, I.; Rigaut, F.; Copeland, M.

    2016-09-01

    The Research School of Astronomy and Astrophysics at the Mount Stromlo Observatory in Canberra, Australia, have been developing adaptive optic (AO) systems for space situational awareness applications. We report on the development and demonstration of an AO system for satellite imaging using a 1 m telescope. The system uses the orbiting object as a natural guide star to measure atmospheric turbulence, and a deformable mirror to provide an optical correction. The AO system utilised modern, high speed and low noise EMCCD technology on both the wavefront sensor and imaging camera to achieve high performance, achieving a Strehl ratio in excess of 30% at 870 nm. Images are post processed with lucky imaging algorithms to further improve the final image quality. We demonstrate the AO system on stellar targets and Iridium satellites, achieving a near diffraction limited full width at half maximum. A specialised realtime controller allows our system to achieve a bandwidth above 100 Hz, with the wavefront sensor and control loop running at 2 kHz. The AO systems we are developing show how ground-based optical sensors can be used to manage the space environment. AO imaging systems can be used for satellite surveillance, while laser ranging can be used to determine precise orbital data used in the critical conjunction analysis required to maintain a safe space environment. We have focused on making this system compact, expandable, and versatile. We are continuing to develop this platform for other space situational awareness applications such as geosynchronous satellite astrometry, space debris characterisation, satellite imaging, and ground-to-space laser communication.

  5. Integrated adaptive optics optical coherence tomography and adaptive optics scanning laser ophthalmoscope system for simultaneous cellular resolution in vivo retinal imaging.

    Science.gov (United States)

    Zawadzki, Robert J; Jones, Steven M; Pilli, Suman; Balderas-Mata, Sandra; Kim, Dae Yu; Olivier, Scot S; Werner, John S

    2011-06-01

    We describe an ultrahigh-resolution (UHR) retinal imaging system that combines adaptive optics Fourier-domain optical coherence tomography (AO-OCT) with an adaptive optics scanning laser ophthalmoscope (AO-SLO) to allow simultaneous data acquisition by the two modalities. The AO-SLO subsystem was integrated into the previously described AO-UHR OCT instrument with minimal changes to the latter. This was done in order to ensure optimal performance and image quality of the AO- UHR OCT. In this design both imaging modalities share most of the optical components including a common AO-subsystem and vertical scanner. One of the benefits of combining Fd-OCT with SLO includes automatic co-registration between two acquisition channels for direct comparison between retinal structures imaged by both modalities (e.g., photoreceptor mosaics or microvasculature maps). Because of differences in the detection scheme of the two systems, this dual imaging modality instrument can provide insight into retinal morphology and potentially function, that could not be accessed easily by a single system. In this paper we describe details of the components and parameters of the combined instrument, including incorporation of a novel membrane magnetic deformable mirror with increased stroke and actuator count used as a single wavefront corrector. We also discuss laser safety calculations for this multimodal system. Finally, retinal images acquired in vivo with this system are presented.

  6. THE CHANDRA COSMOS LEGACY SURVEY: OPTICAL/IR IDENTIFICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Marchesi, S.; Civano, F.; Urry, C. M. [Yale Center for Astronomy and Astrophysics, 260 Whitney Avenue, New Haven, CT 06520 (United States); Elvis, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Salvato, M. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei München (Germany); Brusa, M.; Lanzuisi, G.; Vignali, C. [Dipartimento di Fisica e Astronomia, Università di Bologna, viale Berti Pichat 6/2, I-40127 Bologna (Italy); Comastri, A.; Gilli, R.; Zamorani, G.; Cappelluti, N. [INAF—Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Hasinger, G. [Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Honolulu, HI 96822 (United States); Miyaji, T. [Instituto de Astronomía sede Ensenada, Universidad Nacional Autónoma de México, Km. 103, Carret. Tijunana-Ensenada, Ensenada, BC (Mexico); Treister, E. [Universidad de Concepción, Departamento de Astronomía, Casilla 160-C, Concepción (Chile); Allevato, V.; Finoguenov, A. [Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, FI-00014 Helsinki (Finland); Cardamone, C. [Department of Science, Wheelock College, Boston, MA 02215 (United States); Griffiths, R. E. [Physics and Astronomy Dept., Natural Sciences Division, University of Hawaii at Hilo, 200 W. Kawili Street, Hilo, HI 96720 (United States); Karim, A. [Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, D-53121 Bonn (Germany); and others

    2016-01-20

    We present the catalog of optical and infrared counterparts of the Chandra  COSMOS-Legacy  Survey, a 4.6 Ms Chandra  program on the 2.2 deg{sup 2} of the COSMOS field, combination of 56 new overlapping observations obtained in Cycle 14 with the previous C-COSMOS survey. In this Paper we report the i, K, and 3.6 μm identifications of the 2273 X-ray point sources detected in the new Cycle 14 observations. We use the likelihood ratio technique to derive the association of optical/infrared (IR) counterparts for 97% of the X-ray sources. We also update the information for the 1743 sources detected in C-COSMOS, using new K and 3.6 μm information not available when the C-COSMOS analysis was performed. The final catalog contains 4016 X-ray sources, 97% of which have an optical/IR counterpart and a photometric redshift, while ≃54% of the sources have a spectroscopic redshift. The full catalog, including spectroscopic and photometric redshifts and optical and X-ray properties described here in detail, is available online. We study several X-ray to optical (X/O) properties: with our large statistics we put better constraints on the X/O flux ratio locus, finding a shift toward faint optical magnitudes in both soft and hard X-ray band. We confirm the existence of a correlation between X/O and the the 2–10 keV luminosity for Type 2 sources. We extend to low luminosities the analysis of the correlation between the fraction of obscured AGNs and the hard band luminosity, finding a different behavior between the optically and X-ray classified obscured fraction.

  7. Adaptive-optic approach to mitigating aero-optic disturbances for a forced shear layer

    Science.gov (United States)

    Nightingale, Alice M.

    Non-uniform, variable-density fields, resulting from compressibility effects in turbulent flows, are the source of aero-optical distortions which cause significant reductions in optical system performance. As a laser beam transverses through an optically active medium, containing index-of-refraction variations, several optical phenomena occur including beam wander, image distortion, and beam defocus. When encountering a variation in the index field, light waves refract causing an otherwise planar wavefront of a laser beam to become aberrated, contributing to the adverse effects mentioned above. Adaptive-Optics (AO) is a technique used to correct for such spatially and temporally varying aberrations on an optical beam by applying a conjugate waveform correction prior to the beams transmission through the flow. Conventional AO systems are bandwidth limited by real-time processing issues and wavefront sensor limitations. Therefore, an alternative to the conventional AO approach has been proposed, developed and evaluated with the goal of overcoming such bandwidth limitations. The alternative AO system, presented throughout this document, consists of two main features; feed-forward flow control and a phase-locked-loop AO control strategy. Initially irregular, unpredictable large-scale structures within a shear layer are regularized using flow control. Subsequently, the resulting optical wavefront, and corresponding optical signal, emerging from the regularized flow becomes more periodic and predictable effectively reducing the bandwidth necessary to make real-time corrections. A phase-lock-loop controller is then used to perform real-time corrections. Wavefront corrections are estimated based upon the regularized flow, while two small aperture laser beams provide a non-intrusive means of acquiring amplitude and phase error measurements. The phase-lock-loop controller uses these signals as feedback to synchronize the deformable mirror's waveform to that of the shear

  8. Lasers, lenses and light curves : adaptive optics microscopy and peculiar transiting exoplanets

    NARCIS (Netherlands)

    Werkhoven, Theodorus Isaak Mattheus van

    2014-01-01

    In the first part of this thesis, we present an adaptive optics implementation for multi-photon microscopy correcting sample-induced wavefront aberrations using either direct wavefront sensing to run a close-loop adaptive optics system (Chapter 3), or use a model-based sensorless approach to iterati

  9. Variability of Optical Counterparts in the Chandra Galactic Bulge Survey

    CERN Document Server

    Britt, Christopher T; Johnson, C B; Baldwin, A; Jonker, P G; Nelemans, G; Torres, M A P; Maccarone, T; Steeghs, D; Greiss, S; Heinke, C; Bassa, C G; Collazzi, A; Villar, A; Gabb, M; Gossen, L

    2014-01-01

    We present optical lightcurves of variable stars consistent with the positions of X-ray sources identified with the Chandra X-ray Observatory for the Chandra Galactic Bulge Survey. Using data from the Mosaic-II instrument on the Blanco 4m Telescope at CTIO, we gathered time-resolved photometric data on timescales from $\\sim2$ hr to 8 days over the $\\frac{3}{4}$ of the X-ray survey containing sources from the initial GBS catalog. Among the lightcurve morphologies we identify are flickering in interacting binaries, eclipsing sources, dwarf nova outbursts, ellipsoidal variations, long period variables, spotted stars, and flare stars. $87\\%$ of X-ray sources have at least one potential optical counterpart. $24\\%$ of these candidate counterparts are detectably variable; a much greater fraction than expected for randomly selected field stars, which suggests that most of these variables are real counterparts. We discuss individual sources of interest, provide variability information on candidate counterparts, and di...

  10. Adaptive optics for fluorescence wide-field microscopy using spectrally independent guide star and markers.

    Science.gov (United States)

    Vermeulen, Pierre; Muro, Eleonora; Pons, Thomas; Loriette, Vincent; Fragola, Alexandra

    2011-07-01

    We describe the implementation and use of an adaptive optics loop in the imaging path of a commercial wide field microscope. We show that it is possible to maintain the optical performances of the original microscope when imaging through aberrant biological samples. The sources used for illuminating the adaptive optics loop are spectrally independent, in excitation and emission, from the sample, so they do not appear in the final image, and their use does not contribute to the sample bleaching. Results are compared with equivalent images obtained with an identical microscope devoid of adaptive optics system.

  11. Update on Optical Design of Adaptive Optics System at Lick Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Bauman, B J; Gavel, D T; Waltjen, K E; Freeze, G J; Hurd, R L; Gates, E I; Max, C E; Olivier, S S; Pennington, D M

    2001-07-31

    In 1999, we presented our plan to upgrade the adaptive optics (AO) system on the Lick Observatory Shane telescope (3m) from a prototype instrument pressed into field service to a facility instrument. This paper updates the progress of that plan and details several important improvements in the alignment and calibration of the AO bench. The paper also includes a discussion of the problems seen in the original design of the tip/tilt (t/t) sensor used in laser guide star mode, and how these problems were corrected with excellent results.

  12. Point spread function reconstruction validated using on-sky CANARY data in multiobject adaptive optics mode

    Science.gov (United States)

    Martin, Olivier A.; Correia, Carlos M.; Gendron, Eric; Rousset, Gerard; Gratadour, Damien; Vidal, Fabrice; Morris, Tim J.; Basden, Alastair G.; Myers, Richard M.; Neichel, Benoit; Fusco, Thierry

    2016-10-01

    In preparation of future multiobject spectrographs (MOS) whose one of the major role is to provide an extensive statistical studies of high redshifted galaxies surveyed, the demonstrator CANARY has been designed to tackle technical challenges related to open-loop adaptive optics (AO) control with jointed Natural Guide Star and Laser Guide Star tomography. We have developed a point spread function (PSF) reconstruction algorithm dedicated to multiobject adaptive optics systems using system telemetry to estimate the PSF potentially anywhere in the observed field, a prerequisite to postprocess AO-corrected observations in integral field spectroscopy. We show how to handle off-axis data to estimate the PSF using atmospheric tomography and compare it to a classical approach that uses on-axis residual phase from a truth sensor observing a natural bright source. We have reconstructed over 450 on-sky CANARY PSFs and we get bias/1-σ standard-deviation (std) of 1.3/4.8 on the H-band Strehl ratio (SR) with 92.3% of correlation between reconstructed and sky SR. On the full-width at half-maximum, we get, respectively, 2.94 mas, 19.9 mas, and 88.3% for the bias, std, and correlation. The reference method achieves 0.4/3.5/95% on the SR and 2.71 mas/14.9 mas/92.5% on the FWHM for the bias/std/correlation.

  13. Modeling and Control of Magnetic Fluid Deformable Mirrors for Adaptive Optics Systems

    CERN Document Server

    Wu, Zhizheng; Ben Amara, Foued

    2013-01-01

    Modeling and Control of Magnetic Fluid Deformable Mirrors for Adaptive Optics Systems presents a novel design of wavefront correctors based on magnetic fluid deformable mirrors (MFDM) as well as corresponding control algorithms. The presented wavefront correctors are characterized by their linear, dynamic response. Various mirror surface shape control algorithms are presented along with experimental evaluations of the performance of the resulting adaptive optics systems. Adaptive optics (AO) systems are used in various fields of application to enhance the performance of optical systems, such as imaging, laser, free space optical communication systems, etc. This book is intended for undergraduate and graduate students, professors, engineers, scientists and researchers working on the design of adaptive optics systems and their various emerging fields of application. Zhizheng Wu is an associate professor at Shanghai University, China. Azhar Iqbal is a research associate at the University of Toronto, Canada. Foue...

  14. CATS: Optical to Near-Infrared Colors of the Bulge and Disk of Two z=0.7 Galaxies Using HST and Keck Laser Adaptive Optics Imaging

    CERN Document Server

    Steinbring, E; Metevier, A J; Koo, D C; Chun, M R; Simard, L; Larkin, J E; Max, C E

    2008-01-01

    We have employed laser guide star (LGS) adaptive optics (AO) on the Keck II telescope to obtain near-infrared (NIR) images in the Extended Groth Strip (EGS) deep galaxy survey field. This is a continuation of our Center for Adaptive Optics Treasury Survey (CATS) program of targeting 0.5Surveys (ACS) and the Near Infared Camera and Multiobject Spectrograph (NICMOS). Our AO images at 2.2 microns (K') are comparable in depth to those from HST, have Strehl ratios up to 0.4, and FWHM resolutions superior to that from NICMOS. By sampling the field with the LGS at different positions, we obtain better quality AO images than with an immovable natural guide star. As examples of the power of adding LGS AO to HST data we study the optical to NIR colors and color gradients of the bulge and disk of two galaxies in the field with z=0.7.

  15. The Chandra COSMOS Legacy survey: optical/IR identifications

    CERN Document Server

    Marchesi, S; Elvis, M; Salvato, M; Brusa, M; Comastri, A; Gilli, R; Hasinger, G; Lanzuisi, G; Miyaji, T; Treister, E; Urry, C M; Vignali, C; Zamorani, G; Allevato, V; Cappelluti, N; Cardamone, C; Finoguenov, A; Griffiths, R E; Karim, A; Laigle, C; LaMassa, S M; Jahnke, K; Ranalli, P; Schawinski, K; Schinnerer, E; Silverman, J D; Smolcic, V; Suh, H; Trakhtenbrot, B

    2015-01-01

    We present the catalog of optical and infrared counterparts of the Chandra COSMOS-Legacy Survey, a 4.6 Ms Chandra program on the 2.2 square degrees of the COSMOS field, combination of 56 new overlapping observations obtained in Cycle 14 with the previous C-COSMOS survey. In this Paper we report the i, K, and 3.6 micron identifications of the 2273 X-ray point sources detected in the new Cycle 14 observations. We use the likelihood ratio technique to derive the association of optical/infrared (IR) counterparts for 97% of the X-ray sources. We also update the information for the 1743 sources detected in C-COSMOS, using new K and 3.6 micron information not available when the C-COSMOS analysis was performed. The final catalog contains 4016 X-ray sources, 97% of which have an optical/IR counterpart and a photometric redshift, while 54% of the sources have a spectroscopic redshift. The full catalog, including spectroscopic and photometric redshifts and optical and X-ray properties described here in detail, is availa...

  16. Adaptive Optics Reveals Photoreceptor Abnormalities in Diabetic Macular Ischemia

    Science.gov (United States)

    Nesper, Peter L.; Scarinci, Fabio

    2017-01-01

    Diabetic macular ischemia (DMI) is a phenotype of diabetic retinopathy (DR) associated with chronic hypoxia of retinal tissue. The goal of this prospective observational study was to report evidence of photoreceptor abnormalities using adaptive optics scanning laser ophthalmoscopy (AOSLO) in eyes with DR in the setting of deep capillary plexus (DCP) non-perfusion. Eleven eyes from 11 patients (6 women, age 31–68), diagnosed with DR without macular edema, underwent optical coherence tomography angiography (OCTA) and AOSLO imaging. One patient without OCTA imaging underwent fluorescein angiography to characterize the enlargement of the foveal avascular zone. The parameters studied included photoreceptor heterogeneity packing index (HPi) on AOSLO, as well as DCP non-perfusion and vessel density on OCTA. Using AOSLO, OCTA and spectral domain (SD)-OCT, we observed that photoreceptor abnormalities on AOSLO and SD-OCT were found in eyes with non-perfusion of the DCP on OCTA. All eight eyes with DCP non-flow on OCTA showed photoreceptor abnormalities on AOSLO. Six of the eight eyes also had outer retinal abnormalities on SD-OCT. Three eyes with DR and robust capillary perfusion of the DCP had normal photoreceptors on SD-OCT and AOSLO. Compared to eyes with DR without DCP non-flow, the eight eyes with DCP non-flow had significantly lower HPi (P = 0.013) and parafoveal DCP vessel density (P = 0.016). We found a significant correlation between cone HPi and parafoveal DCP vessel density (r = 0.681, P = 0.030). Using a novel approach with AOSLO and OCTA, this study shows an association between capillary non-perfusion of the DCP and abnormalities in the photoreceptor layer in eyes with DR. This observation is important in confirming the significant contribution of the DCP to oxygen requirements of photoreceptors in DMI, while highlighting the ability of AOSLO to detect subtle photoreceptor changes not always visible on SD-OCT. PMID:28068435

  17. The Second Byurakan Survey Galaxies. I. The Optical Database

    CERN Document Server

    Gyulzadyan, M; Adibekyan, V Zh; Allen, R J; Kunth, D; Petrosian, A; Stepanian, J A

    2011-01-01

    A database for the entire catalog of the Second Byurakan Survey (SBS) galaxies is presented. It contains new measurements of their optical parameters and additional information taken from the literature and other databases. The measurements were made using Ipg(near-infrared), Fpg(red) and Jpg(blue) band images from photographic sky survey plates obtained by the Palomar Schmidt telescope and extracted from the STScI Digital Sky Survey (DSS). The database provides accurate coordinates, morphological type, spectral and activity classes, apparent magnitudes and diameters, axial ratios, and position angles, as well as number counts of neighboring objects in a circle of radius 50 kpc. The total number of individual SBS objects in the database is now 1676. The 188 Markarian galaxies which were re-discovered by SBS are not included in this database. We also include redshifts that are now available for 1576 SBS objects, as well as 2MASS infrared magnitudes for 1117 SBS galaxies.

  18. Robo-AO KP: A new era in robotic adaptive optics

    Science.gov (United States)

    Riddle, Reed L.; Baranec, Christoph; Law, Nicholas M.; Kulkarni, Shrinivas R.; Duev, Dmitry; Ziegler, Carl; Jensen-Clem, Rebecca M.; Atkinson, Dani Eleanor; Tanner, Angelle M.; Zhang, Celia; Ray, Amy

    2016-01-01

    Robo-AO is the first and only fully automated adaptive optics laser guide star AO instrument. It was developed as an instrument for 1-3m robotic telescopes, in order to take advantage of their availability to pursue large survey programs and target of opportunity observations that aren't possible with other AO systems. Robo-AO is currently the most efficient AO system in existence, and it can achieve an observation rate of 20+ science targets per hour. In more than three years of operations at Palomar Observatory, it has been quite successful, producing technology that is being adapted by other AO systems and robotic telescope projects, as well as several high impact scientific publications. Now, Robo-AO has been selected to take over operation of the Kitt Peak National Observatory 2.1m telescope. This will give Robo-AO KP the opportunity to pursue multiple science programs consisting of several thousand targets each during the three years it will be on the telescope. One-sixth of the observing time will be allocated to the US community through the NOAO TAC process. This presentation will discuss the process adapting Robo-AO to the KPNO 2.1m telescope, the plans for integration and initial operations, and the science operations and programs to be pursued.

  19. Wide field of view adaptive optical system for lightweight deployable telescope technologies

    Science.gov (United States)

    McComas, Brian K.; Cermak, Michael A.; Friedman, Edward J.

    2003-02-01

    A NASA research contract (NAS1-00116) was awarded to Ball Aerospace & Technologies Corp. in January 2000 to study wide field-of-view adaptive optical systems. These systems will be required on future high resolution Earth remote sensing systems that employ large, flexible, lightweight, deployed primary mirrors. The deformations from these primary mirrors will introduce aberrations into the optical system, which must be removed by corrective optics. For economic reasons, these remote sensing systems must have a large field-of-view (a few degrees). Unlike ground-based adaptive optical systems, which have a negligible field-of-view, the adaptive optics on these space-based remote sensing systems will be required to correct for the deformations in the primary mirror over the entire field-of-view. A new error function, which is an enhancement to conventional adaptive optics, for wide field-of-view optical systems will be introduced. This paper will present the goals of the NASA research project and its progress. The initial phase of this research project is a demonstration of the wide field-of-view adaptive optics theory. A breadboard has been designed and built for this purpose. The design and assembly of the breadboard will be presented, along with the final results for this phase of the research project. Finally, this paper will show the applicability of wide field-of-view adaptive optics to space-based astronomical systems.

  20. Robo-AO: autonomous and replicable laser-adaptive-optics and science system

    CERN Document Server

    Baranec, C; Ramaprakash, A N; Law, N; Tendulkar, S; Kulkarni, S; Dekany, R; Bui, K; Davis, J; Burse, M; Das, H; Hildebrandt, S; Punnadi, S; Smith, R; 10.1117/12.924867

    2012-01-01

    We have created a new autonomous laser-guide-star adaptive-optics (AO) instrument on the 60-inch (1.5-m) telescope at Palomar Observatory called Robo-AO. The instrument enables diffraction-limited resolution observing in the visible and near-infrared with the ability to observe well over one-hundred targets per night due to its fully robotic operation. Robo- AO is being used for AO surveys of targets numbering in the thousands, rapid AO imaging of transient events and longterm AO monitoring not feasible on large diameter telescope systems. We have taken advantage of cost-effective advances in deformable mirror and laser technology while engineering Robo-AO with the intention of cloning the system for other few-meter class telescopes around the world.

  1. Robo-AO: autonomous and replicable laser-adaptive-optics and science system

    Science.gov (United States)

    Baranec, C.; Riddle, R.; Ramaprakash, A. N.; Law, N.; Tendulkar, S.; Kulkarni, S.; Dekany, R.; Bui, K.; Davis, J.; Burse, M.; Das, H.; Hildebrandt, S.; Punnadi, S.; Smith, R.

    2012-07-01

    We have created a new autonomous laser-guide-star adaptive-optics (AO) instrument on the 60-inch (1.5-m) telescope at Palomar Observatory called Robo-AO. The instrument enables diffraction-limited resolution observing in the visible and near-infrared with the ability to observe well over one-hundred targets per night due to its fully robotic operation. Robo-AO is being used for AO surveys of targets numbering in the thousands, rapid AO imaging of transient events and long-term AO monitoring not feasible on large diameter telescope systems. We have taken advantage of cost-effective advances in deformable mirror and laser technology while engineering Robo-AO with the intention of cloning the system for other few-meter class telescopes around the world.

  2. Close Companions to Nearby Young Stars from Adaptive Optics Imaging on VLT and Keck

    Science.gov (United States)

    Haisch, Karl E.; Jayawardhana, Ray; Brandeker, Alexis; Mardones, Diego

    We report the results of VLT and Keck adaptive optics surveys of known members of the η Chamaeleontis, MBM 12, and TW Hydrae (TWA) associations to search for close companions. The multiplicity statistics of η Cha, MBM 12, and TWA are quite high compared with other clusters and associations, although our errors are large due to small number statistics. We have resolved S18 in MBM 12 and RECX 9 in η Cha into triples for the first time. The tight binary TWA 5Aab in the TWA offers the prospect of measuring the dynamical masses of both components as well as an independent distance to the system within a few years. The AO detection of the close companion to the nearby young star χ1 Orionis, previously inferred from radial velocity and astrometric observations, has already made it possible to derive the dynamical masses of that system without any astrophysical assumption.

  3. Close Companions to Nearby Young Stars from Adaptive Optics Imaging on VLT and Keck

    CERN Document Server

    Haisch, K E; Brandeker, A; Mardones, D; Jr., Karl E. Haisch; Jayawardhana, Ray; Brandeker, Alexis; Mardones, Diego

    2003-01-01

    We report the results of VLT and Keck adaptive optics surveys of known members of the Eta Chamaeleontis, MBM 12, and TW Hydrae (TWA) associations to search for close companions. The multiplicity statistics of Eta Cha, MBM 12, and TWA are quite high compared with other clusters and associations, although our errors are large due to small number statistics. We have resolved S18 in MBM 12 and RECX 9 in Eta Cha into triples for the first time. The tight binary TWA 5Aab in the TWA offers the prospect of measuring the dynamical masses of both components as well as an independent distance to the system within a few years. The AO detection of the close companion to the nearby young star Chi^1 Orionis, previously inferred from radial velocity and astrometric observations, has already made it possible to derive the dynamical masses of that system without any astrophysical assumption.

  4. Morphologies of High Redshift, Dust Obscured Galaxies from Keck Laser Guide Star Adaptive Optics

    CERN Document Server

    Melbourne, J; Armus, Lee; Dey, Arjun; Brand, K; Thompson, D; Soifer, B T; Matthews, K; Jannuzi, B T; Houck, J R

    2008-01-01

    Spitzer MIPS images in the Bootes field of the NOAO Deep Wide-Field Survey have revealed a class of extremely dust obscured galaxy (DOG) at z~2. The DOGs are defined by very red optical to mid-IR (observed-frame) colors, R - [24 um] > 14 mag, i.e. f_v (24 um) / f_v (R) > 1000. They are Ultra-Luminous Infrared Galaxies with L_8-1000 um > 10^12 -10^14 L_sun, but typically have very faint optical (rest-frame UV) fluxes. We imaged three DOGs with the Keck Laser Guide Star Adaptive Optics (LGSAO) system, obtaining ~0.06'' resolution in the K'-band. One system was dominated by a point source, while the other two were clearly resolved. Of the resolved sources, one can be modeled as a exponential disk system. The other is consistent with a de Vaucouleurs profile typical of elliptical galaxies. The non-parametric measures of their concentration and asymmetry, show the DOGs to be both compact and smooth. The AO images rule out double nuclei with separations of greater than 0.1'' (< 1 kpc at z=2), making it unlikely ...

  5. SOAR Adaptive Optics Observations of the Globular Cluster NGC 6496

    Science.gov (United States)

    Fraga, Luciano; Kunder, Andrea; Tokovinin, Andrei

    2013-06-01

    We present high-quality BVRI photometric data in the field of globular cluster NGC 6496 obtained with the SOAR Telescope Adaptive Module (SAM). Our observations were collected as part of the ongoing SAM commissioning. The distance modulus and cluster color excess as found from the red clump are (m - M) V = 15.71 ± 0.02 mag and E(V - I) = 0.28 ± 0.02 mag. An age of 10.5 ± 0.5 Gyr is determined from the difference in magnitude between the red clump and the subgiant branch. These parameters are in excellent agreement with the values derived from isochrone fitting. From the color-magnitude diagram we find a metallicity of [Fe/H] = -0.65 dex and hence support a disk classification for NGC 6496. The complete BVRI data set for NGC 6469 is made available in the electronic edition of the Journal. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

  6. Adaptive optics near infrared integral field spectroscopy of NGC 2992

    CERN Document Server

    Friedrich, S; Hicks, E K S; Engel, H; Müller-Sánchez, F; Genzel, R; Tacconi, L J

    2010-01-01

    NGC 2992 is an intermediate Seyfert 1 galaxy showing outflows on kilo parsec scales which might be due either to AGN or starburst activity. We therefore aim at investigating its central region for a putative starburst in the past and its connection to the AGN and the outflows. Observations were performed with the adaptive optics near infrared integral field spectrograph SINFONI on the VLT, complemented by longslit observations with ISAAC on the VLT, as well as N- and Q-band data from the Spitzer archive. The spatial and spectral resolutions of the SINFONI data are 50 pc and 83 km/s, respectively. The field of view of 3" x 3" corresponds to 450 pc x 450 pc. Br_gamma equivalent width and line fluxes from PAHs were compared to stellar population models to constrain the age of the putative recent star formation. A simple geometric model of two mutually inclined disks and an additional cone to describe an outflow was developed to explain the observed complex velocity field in H_2 1-0S(1). The morphologies of the B...

  7. New challenges for Adaptive Optics Extremely Large Telescopes

    CERN Document Server

    Le Louarn, M; Sarazin, M; Tokovinin, A

    2000-01-01

    The performance of an adaptive optics (AO) system on a 100m diameter ground based telescope working in the visible range of the spectrum is computed using an analytical approach. The target Strehl ratio of 60% is achieved at 0.5um with a limiting magnitude of the AO guide source near R~10, at the cost of an extremely low sky coverage. To alleviate this problem, the concept of tomographic wavefront sensing in a wider field of view using either natural guide stars (NGS) or laser guide stars (LGS) is investigated. These methods use 3 or 4 reference sources and up to 3 deformable mirrors, which increase up to 8-fold the corrected field size (up to 60\\arcsec at 0.5 um). Operation with multiple NGS is limited to the infrared (in the J band this approach yields a sky coverage of 50% with a Strehl ratio of 0.2). The option of open-loop wavefront correction in the visible using several bright NGS is discussed. The LGS approach involves the use of a faint (R ~22) NGS for low-order correction, which results in a sky cov...

  8. AdapTube: Adaptive Optics animations for tutorial purpose

    Science.gov (United States)

    Dima, Marco; Ragazzoni, Roberto; Bergomi, Maria; Farinato, Jacopo; Magrin, Demetrio; Marafatto, Luca; Viotto, Valentina

    2013-12-01

    As it happens in most scientific fields, many Adaptive Optics concepts and instrumental layouts are not easily understandable. Both in outreach and in the framework of addressing experts, computer graphics (CG) and, in particular, animation can aid the speaker and the auditor to simplify concept description, translating them into a more direct message. This paper presents a few examples of how some instruments, as Shack-Hartmann and Pyramid wavefront sensors, or concepts, like MCAO and MOAO, have been depicted and sometimes compared in a more intuitive way, emphasizing differences, pros and cons. Some example linking animation to the real world are also outlined, pushing the boundaries of the way a complicated concept can be illustrated embedding complex drawings into the explanation of a human. The used CG software, which is completely open source and will be presented and briefly described, turns out to be a valid communication tool to highlight what, on a piece of paper, could seem obscure. This poster aims at showing how concepts, such as Pyramid WFS, GLAO, MCAO and GMCAO, sometimes very difficult to explain on paper, can be much more easily outlined by means of dedicated animation SW. Blender is a very powerful freeware SW, used by our group since years to make tutorial videos and explanatory movies, a few examples of which are presented here.

  9. Focusing adaptive-optics for neutron spectroscopy at extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    Simeoni, G. G., E-mail: ggsimeoni@outlook.com [Heinz Maier-Leibnitz Zentrum (MLZ), FRM II, Technical University of Munich, D-85748 Garching (Germany); Physics Department E13, Technical University of Munich, D-85748 Garching (Germany); Valicu, R. G. [Heinz Maier-Leibnitz Zentrum (MLZ), FRM II, Technical University of Munich, D-85748 Garching (Germany); Physics Department E13, Technical University of Munich, D-85748 Garching (Germany); Physics Department E21, Technical University of Munich, D-85748 Garching (Germany); Borchert, G. [Heinz Maier-Leibnitz Zentrum (MLZ), FRM II, Technical University of Munich, D-85748 Garching (Germany); Böni, P. [Physics Department E21, Technical University of Munich, D-85748 Garching (Germany); Rasmussen, N. G. [Nanoscience Center, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen (Denmark); Yang, F.; Kordel, T.; Holland-Moritz, D.; Kargl, F.; Meyer, A. [Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt, D-51170 Köln (Germany)

    2015-12-14

    Neutron Spectroscopy employing extreme-conditions sample environments is nowadays a crucial tool for the understanding of fundamental scientific questions as well as for the investigation of materials and chemical-physical properties. For all these kinds of studies, an increased neutron flux over a small sample area is needed. The prototype of a focusing neutron guide component, developed and produced completely at the neutron source FRM II in Garching (Germany), has been installed at the time-of-flight (TOF) disc-chopper neutron spectrometer TOFTOF and came into routine-operation. The design is based on the compressed Archimedes' mirror concept for finite-size divergent sources. It represents a unique device combining the supermirror technology with Adaptive Optics, suitable for broad-bandwidth thermal-cold TOF neutron spectroscopy (here optimized for 1.4–10 Å). It is able to squeeze the beam cross section down to a square centimeter, with a more than doubled signal-to-background ratio, increased efficiency at high scattering angles, and improved symmetry of the elastic resolution function. We present a comparison between the simulated and measured beam cross sections, as well as the performance of the instrument within real experiments. This work intends to show the unprecedented opportunities achievable at already existing instruments, along with useful guidelines for the design and construction of next-generation neutron spectrometers.

  10. Novel adaptive fiber-optics collimator for coherent beam combination.

    Science.gov (United States)

    Zhi, Dong; Ma, Pengfei; Ma, Yanxing; Wang, Xiaolin; Zhou, Pu; Si, Lei

    2014-12-15

    In this manuscript, we experimentally validate a novel design of adaptive fiber-optics collimator (AFOC), which utilizes two levers to enlarge the movable range of the fiber end cap. The enlargement of the range makes the new AFOC possible to compensate the end-cap/tilt aberration in fiber laser beam combining system. The new AFOC based on flexible hinges and levers was fabricated and the performance of the new AFOC was tested carefully, including its control range, frequency response and control accuracy. Coherent beam combination (CBC) of two 5-W fiber amplifiers array with simultaneously end-cap/tilt control and phase-locking control was implemented successfully with the novel AFOC. Experimental results show that the average normalized power in the bucket (PIB) value increases from 0.311 to 0.934 with active phasing and tilt aberration compensation simultaneously, and with both controls on, the fringe contrast improves to more than 82% from 0% for the case with both control off. This work presents a promising structure for tilt aberration control in high power CBC system.

  11. Adaptive optics for ultra short pulsed lasers in UHV environment

    Science.gov (United States)

    Deneuville, Francois; Ropert, Laurent; Sauvageot, Paul; Theis, Sébastien

    2015-02-01

    ISP SYSTEM has developed an electro-mechanical deformable mirror compatible with Ultra High Vacuum environment, suitable for ultra short pulsed lasers. The design of the MD-AME deformable mirror is based on force application on numerous locations. μ-AME actuators are driven by stepper motors, and their patented special design allows controlling the force with a very high accuracy. Materials and assembly method have been adapted to UHV constraints and the performances were evaluated on a first application for a beam with a diameter of 250mm. A Strehl ratio above 0.9 was reached for this application. Optical aberrations up to Zernike order 5 can be corrected with a very low residual error as for standard MD-AME mirror. Amplitude can reach up to several hundreds of μm for low order corrections. Hysteresis is lower than 0.1% and linearity better than 99%. Contrary to piezo-electric actuators, the μ-AME actuators avoid print-through effects and they permit to keep the mirror shape stable even unpowered, providing a high resistance to electro-magnetic pulses. The deformable mirror design allows changing easily an actuator or even the membrane if needed, in order to improve the facility availability. They are designed for circular, square or elliptical aperture from 30mm up to 500mm or more, with incidence angle from 0° to 45°. They can be equipped with passive or active cooling for high power lasers with high repetition rate.

  12. Point spread function determination for Keck adaptive optics

    Science.gov (United States)

    Ragland, S.; Jolissaint, L.; Wizinowich, P.; van Dam, M. A.; Mugnier, L.; Bouxin, A.; Chock, J.; Kwok, S.; Mader, J.; Witzel, G.; Do, Tuan; Fitzgerald, M.; Ghez, A.; Lu, J.; Martinez, G.; Morris, M. R.; Sitarski, B.

    2016-07-01

    One of the primary scientific limitations of adaptive optics (AO) has been the incomplete knowledge of the point spread function (PSF), which has made it difficult to use AO for accurate photometry and astrometry in both crowded and sparse fields, for extracting intrinsic morphologies and spatially resolved kinematics, and for detecting faint sources in the presence of brighter sources. To address this limitation, we initiated a program to determine and demonstrate PSF reconstruction for science observations obtained with Keck AO. This paper aims to give a broad view of the progress achieved in implementing a PSF reconstruction capability for Keck AO science observations. This paper describes the implementation of the algorithms, and the design and development of the prototype operational tools for automated PSF reconstruction. On-sky performance is discussed by comparing the reconstructed PSFs to the measured PSF's on the NIRC2 science camera. The importance of knowing the control loop performance, accurate mapping of the telescope pupil to the deformable mirror and the science instrument pupil, and the telescope segment piston error are highlighted. We close by discussing lessons learned and near-term future plans.

  13. Keck Adaptive Optics Observations of TW Hydrae Association Members

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B; Max, C; Zuckerman, B; Becklin, E E; Kaisler, D; Lowrance, P; Weinberger, A; Chirstou, J; Schneider, G; Acton, S

    2001-05-30

    Adaptive optics (AO) on 8-10 m telescopes is an enormously powerful tool for studying young nearby stars. It is especially useful for searching for companions. Using AO on the 10-m W.M. Keck II telescope we have measured the position of the brown dwarf companion to TWA5 and resolved the primary into an 0.055{double_prime} double. Over the next several years follow-up astrometry should permit an accurate determination of the masses of these young stars. We have also re-observed the candidate extrasolar planet TWAGB, but measurements of its motion relative to TWA6A are inconclusive. We are carrying out a search for new planetary or brown dwarf companions to TWA stars and, if current giant planet models are correct, are currently capable of detecting a 1 Jupiter-mass companion at {approx} 1.0{double_prime} and a 5 Jupiter-mass companion at {approx} 0.5{double_prime} around a typical TWA member.

  14. Optical techniques to understand biofunctional adaptation in human dentine

    Science.gov (United States)

    Kishen, Anil; Asundi, Anand K.

    2004-08-01

    Human tooth structure in the oral environment is subjected to mechanical forces and thermal fluctuations. Dentine, the major component of the tooth structure, is a bio-composite, mainly composed of a highly mineralized phase and a collagenous phase. When subjected to changes in load and/or temperature, dentine will experience stresses and strains distribution within their structure. Though such effects are found to cause deleterious effects on artificial dental restorations, biological structures such as dentine seem to posses an inherent ability to adapt to functional thermo-mechanical loads. Optical techniques enable visualization and quantification of deformation, strain and stress on dental structures and provide a better understanding on their thermo-mechanical response. In this study 2-dimensional and 3-dimensional digital photoelasticity, digital moiré interferometry and Electronic Speckle Pattern Interferometry (ESPI) are all shown to be quite promising in this application. This paper will highlight these techniques and the corresponding applications. These experiments will aid in designing and development of better dental restorations and implants in clinical practice.

  15. Adaptive optics imaging of the MBM 12 association

    CERN Document Server

    Chauvin, G; Fusco, T; Lagrange, A M; Beuzit, J L; Mouillet, D; Augereau, J C

    2002-01-01

    We report adaptive optics (AO) observations of the young and nearby association MBM 12 obtained with the Canada-France-Hawaii Telescope. Our main observational result is the discovery of six new binary systems, LkHa 264, E 0255+2018, RX J0255.4+2005, S18, MBM 12-10, RX J0255.3+1915, and the confirmation of HD 17332, already known as a binary. We also detected a possible quadruple system. It is composed of the close binary LkHa 263 AB (separation of 0.41 ''), of LkH\\alpha 262 located 15.25 '' from LkHa 263 A, and of LkHa 263 C, located 4.1 '' from LkH\\alpha 263 A. A preliminary study of the binary fraction suggests a binary excess in the MBM 12 association as compared to the field and IC 348. Because of the high binarity rate, previous estimations of spectral types and measurements of IR excesses for several candidate members of MBM 12 have to be revised. LkH\\alpha 263 C is a nebulous object that we interpret as a disk oriented almost perfectly edge-on and seen in scattered light. This object has already been ...

  16. Subcarrier Intensity Modulated Optical Wireless Communications:A Survey from Communication Theory Perspective

    Institute of Scientific and Technical Information of China (English)

    Md Zoheb Hassan; Md Jahangir Hossain; Julian Cheng; Victor C M Leung

    2016-01-01

    Subcarrier intensity modulation with direct detection is a modulation/detection technique for optical wireless communication sys⁃tems, where a pre⁃modulated and properly biased radio frequency signal is modulated on the intensity of the optical carrier. The most important benefits of subcarrier intensity modulation are as follows: 1) it does not provide irreducible error floor like the con⁃ventional on⁃off keying intensity modulation with a fixed detection threshold; 2) it provides improved spectral efficiency and sup⁃ports higher order modulation schemes; and 3) it has much less implementation complexity compared to coherent optical wireless communications with heterodyne or homodyne detection. In this paper, we present an up⁃to⁃date review of subcarrier intensity modulated optical wireless communication systems. We survey the error rate and outage performance of subcarrier intensity modu⁃lations in the atmospheric turbulence channels considering different modulation and coding schemes. We also explore different contemporary atmospheric turbulence fading mitigation solutions that can be employed for subcarrier intensity modulation. These solutions include diversity combining, adaptive transmission, relay assisted transmission, multiple⁃subcarrier intensity modulations, and optical orthogonal frequency division multiplexing. Moreover, we review the performance of subcarrier intensity modulations due to the pointing error and synchronization error.

  17. Configurable adaptive optical system for imaging of ground-based targets from space

    Science.gov (United States)

    McComas, Brian K.; Friedman, Edward J.; Hooker, R. Brian; Cermak, Michael A.

    2003-03-01

    Space-based, high resolution, Earth remote sensing systems, that employ large, flexible, lightweight primary mirrors, will require active wavefront correction, in the form of active and adaptive optics, to correct for thermally and vibrationally induced deformations in the optics. These remote sensing systems typically have a large field-of-view. Unlike the adaptive optics on ground-based astronomical telescopes, which have a negligible field-of-view, the adaptive optics on these space-based remote sensing systems will be required to correct the wavefront over the entire field-of-view, which can be several degrees. The error functions for astronomical adaptive optics have been developed for the narrow field-of-view correction of atmospheric turbulence and do not address the needs of wide field space-based systems. To address these needs, a new wide field adaptive optics theory and a new error function are developed. Modeling and experimental results demonstrate the validity of the wide field adaptive optics theory and new error function. This new error function, which is a new extension of conventional adaptive optics, lead to the development of three new types of imaging systems: wide field-of-view, selectable field-of-view, and steerable field-of-view. These new systems can have nearly diffraction-limited performance across the entire field-of-view or a narrow movable region of high-resolution imaging. The factors limiting system performance will be shown. The range of applicability of the wide field adaptive optics theory is shown. The range of applicability is used to avoid limitations in system performance and to estimate the optical systems parameters, which will meet the system"s performance requirements.

  18. Extrapolating Zernike Moments to Predict Future Optical Wave-fronts in Adaptive Optics Using Real Time Data Mining

    CERN Document Server

    Vyas, Akondi; Prasad, B Raghavendra

    2010-01-01

    We present the details of predicting atmospheric turbulence by mining Zernike moment data obtained from simulations as well as experiments. Temporally correlated optical wave-fronts were simulated such that they followed Kolmogorov phase statistics. The wave-fronts reconstructed either by modal or zonal methods can be represented in terms of Zernike moments. The servo lag error in adaptive optics is minimized by predicting Zernike moments in the near future by using the data from the immediate past. It is shown statistically that the prediction accuracy depends on the number of past phase screens used for prediction and servo lag time scales. The algorithm is optimized in terms of these parameters for real time and efficient operation of the adaptive optics system. On an average, we report more than 3% improvement in the wave-front compensation after prediction. This analysis helps in optimizing the design parameters for sensing and correction in closed loop adaptive optics systems.

  19. The Inner Kiloparsec of Mrk 273 with Keck Adaptive Optics

    Science.gov (United States)

    U, Vivian; Medling, Anne; Sanders, David; Max, Claire; Armus, Lee; Iwasawa, Kazushi; Evans, Aaron; Kewley, Lisa; Fazio, Giovanni

    2013-10-01

    There is X-ray, optical, and mid-infrared imaging and spectroscopic evidence that the late-stage ultraluminous infrared galaxy merger Mrk 273 hosts a powerful active galactic nucleus (AGN). However, the exact location of the AGN and the nature of the nucleus have been difficult to determine due to dust obscuration and the limited wavelength coverage of available high-resolution data. Here we present near-infrared integral-field spectra and images of the nuclear region of Mrk 273 taken with OSIRIS and NIRC2 on the Keck II Telescope with laser guide star adaptive optics. We observe three spatially resolved components, and analyze the nuclear molecular and ionized gas emission lines and their kinematics. We confirm the presence of the hard X-ray AGN in the southwest nucleus. In the north nucleus, we find a strongly rotating gas disk whose kinematics indicate a central black hole of mass 1.04 ± 0.1 × 109 M ⊙. The H2 emission line shows an increase in velocity dispersion along the minor axis in both directions, and an increased flux with negative velocities in the southeast direction; this provides direct evidence for a collimated molecular outflow along the axis of rotation of the disk. The third spatially distinct component appears to the southeast, 640 and 750 pc from the north and southwest nuclei, respectively. This component is faint in continuum emission but shows several strong emission line features, including [Si VI] 1.964 μm which traces an extended coronal-line region. The geometry of the [Si VI] emission combined with shock models and energy arguments suggest that [Si VI] in the southeast component must be at least partly ionized by the SW AGN or a putative AGN in the northern disk, either through photoionization or through shock-heating from strong AGN- and circumnuclear-starburst-driven outflows. This lends support to a scenario in which Mrk 273 may be a dual AGN system.

  20. GPU-based computational adaptive optics for volumetric optical coherence microscopy

    Science.gov (United States)

    Tang, Han; Mulligan, Jeffrey A.; Untracht, Gavrielle R.; Zhang, Xihao; Adie, Steven G.

    2016-03-01

    Optical coherence tomography (OCT) is a non-invasive imaging technique that measures reflectance from within biological tissues. Current higher-NA optical coherence microscopy (OCM) technologies with near cellular resolution have limitations on volumetric imaging capabilities due to the trade-offs between resolution vs. depth-of-field and sensitivity to aberrations. Such trade-offs can be addressed using computational adaptive optics (CAO), which corrects aberration computationally for all depths based on the complex optical field measured by OCT. However, due to the large size of datasets plus the computational complexity of CAO and OCT algorithms, it is a challenge to achieve high-resolution 3D-OCM reconstructions at speeds suitable for clinical and research OCM imaging. In recent years, real-time OCT reconstruction incorporating both dispersion and defocus correction has been achieved through parallel computing on graphics processing units (GPUs). We add to these methods by implementing depth-dependent aberration correction for volumetric OCM using plane-by-plane phase deconvolution. Following both defocus and aberration correction, our reconstruction algorithm achieved depth-independent transverse resolution of 2.8 um, equal to the diffraction-limited focal plane resolution. We have translated the CAO algorithm to a CUDA code implementation and tested the speed of the software in real-time using two GPUs - NVIDIA Quadro K600 and Geforce TITAN Z. For a data volume containing 4096×256×256 voxels, our system's processing speed can keep up with the 60 kHz acquisition rate of the line-scan camera, and takes 1.09 seconds to simultaneously update the CAO correction for 3 en face planes at user-selectable depths.

  1. Enhancing Stellar Spectroscopy with Extreme Adaptive Optics and Photonics

    Science.gov (United States)

    Jovanovic, N.; Schwab, C.; Cvetojevic, N.; Guyon, O.; Martinache, F.

    2016-12-01

    Extreme adaptive optics (AO) systems are now in operation across the globe. These systems, capable of high order wavefront correction, deliver Strehl ratios of ∼ 90 % in the near-infrared. Originally intended for the direct imaging of exoplanets, these systems are often equipped with advanced coronagraphs that suppress the on-axis-star, interferometers to calibrate wavefront errors, and low order wavefront sensors to stabilize any tip/tilt residuals to a degree never seen before. Such systems are well positioned to facilitate the detailed spectroscopic characterization of faint substellar companions at small angular separations from the host star. Additionally, the increased light concentration of the point-spread function and the unprecedented stability create opportunities in other fields of astronomy as well, including spectroscopy. With such Strehl ratios, efficient injection into single-mode fibers (SMFs) or photonic lanterns becomes possible. With diffraction-limited components feeding the instrument, calibrating a spectrograph’s line profile becomes considerably easier, as modal noise or imperfect scrambling of the fiber output are no longer an issue. It also opens up the possibility of exploiting photonic technologies for their advanced functionalities, inherent replicability, and small, lightweight footprint to design and build future instrumentation. In this work, we outline how extreme AO systems will enable advanced photonic and diffraction-limited technologies to be exploited in spectrograph design and the impact it will have on spectroscopy. We illustrate that the precision of an instrument based on these technologies, with light injected from an efficient SMF feed would be entirely limited by the spectral content and stellar noise alone on cool stars and would be capable of achieving a radial velocity precision of several m/s; the level required for detecting an exo-Earth in the habitable zone of a nearby M-dwarf.

  2. Numerical Simulations of Optical Turbulence Using an Advanced Atmospheric Prediction Model: Implications for Adaptive Optics Design

    Science.gov (United States)

    Alliss, R.

    2014-09-01

    Optical turbulence (OT) acts to distort light in the atmosphere, degrading imagery from astronomical telescopes and reducing the data quality of optical imaging and communication links. Some of the degradation due to turbulence can be corrected by adaptive optics. However, the severity of optical turbulence, and thus the amount of correction required, is largely dependent upon the turbulence at the location of interest. Therefore, it is vital to understand the climatology of optical turbulence at such locations. In many cases, it is impractical and expensive to setup instrumentation to characterize the climatology of OT, so numerical simulations become a less expensive and convenient alternative. The strength of OT is characterized by the refractive index structure function Cn2, which in turn is used to calculate atmospheric seeing parameters. While attempts have been made to characterize Cn2 using empirical models, Cn2 can be calculated more directly from Numerical Weather Prediction (NWP) simulations using pressure, temperature, thermal stability, vertical wind shear, turbulent Prandtl number, and turbulence kinetic energy (TKE). In this work we use the Weather Research and Forecast (WRF) NWP model to generate Cn2 climatologies in the planetary boundary layer and free atmosphere, allowing for both point-to-point and ground-to-space seeing estimates of the Fried Coherence length (ro) and other seeing parameters. Simulations are performed using a multi-node linux cluster using the Intel chip architecture. The WRF model is configured to run at 1km horizontal resolution and centered on the Mauna Loa Observatory (MLO) of the Big Island. The vertical resolution varies from 25 meters in the boundary layer to 500 meters in the stratosphere. The model top is 20 km. The Mellor-Yamada-Janjic (MYJ) TKE scheme has been modified to diagnose the turbulent Prandtl number as a function of the Richardson number, following observations by Kondo and others. This modification

  3. Temporally adaptive sampling: a case study in rare species survey design with marbled salamanders (Ambystoma opacum.

    Directory of Open Access Journals (Sweden)

    Noah D Charney

    Full Text Available Improving detection rates for elusive species with clumped distributions is often accomplished through adaptive sampling designs. This approach can be extended to include species with temporally variable detection probabilities. By concentrating survey effort in years when the focal species are most abundant or visible, overall detection rates can be improved. This requires either long-term monitoring at a few locations where the species are known to occur or models capable of predicting population trends using climatic and demographic data. For marbled salamanders (Ambystoma opacum in Massachusetts, we demonstrate that annual variation in detection probability of larvae is regionally correlated. In our data, the difference in survey success between years was far more important than the difference among the three survey methods we employed: diurnal surveys, nocturnal surveys, and dipnet surveys. Based on these data, we simulate future surveys to locate unknown populations under a temporally adaptive sampling framework. In the simulations, when pond dynamics are correlated over the focal region, the temporally adaptive design improved mean survey success by as much as 26% over a non-adaptive sampling design. Employing a temporally adaptive strategy costs very little, is simple, and has the potential to substantially improve the efficient use of scarce conservation funds.

  4. Temporally adaptive sampling: a case study in rare species survey design with marbled salamanders (Ambystoma opacum).

    Science.gov (United States)

    Charney, Noah D; Kubel, Jacob E; Eiseman, Charles S

    2015-01-01

    Improving detection rates for elusive species with clumped distributions is often accomplished through adaptive sampling designs. This approach can be extended to include species with temporally variable detection probabilities. By concentrating survey effort in years when the focal species are most abundant or visible, overall detection rates can be improved. This requires either long-term monitoring at a few locations where the species are known to occur or models capable of predicting population trends using climatic and demographic data. For marbled salamanders (Ambystoma opacum) in Massachusetts, we demonstrate that annual variation in detection probability of larvae is regionally correlated. In our data, the difference in survey success between years was far more important than the difference among the three survey methods we employed: diurnal surveys, nocturnal surveys, and dipnet surveys. Based on these data, we simulate future surveys to locate unknown populations under a temporally adaptive sampling framework. In the simulations, when pond dynamics are correlated over the focal region, the temporally adaptive design improved mean survey success by as much as 26% over a non-adaptive sampling design. Employing a temporally adaptive strategy costs very little, is simple, and has the potential to substantially improve the efficient use of scarce conservation funds.

  5. Engineering aspects of the Large Binocular Telescope Observatory adaptive optics systems

    Science.gov (United States)

    Brusa, Guido; Ashby, Dave; Christou, Julian C.; Kern, Jonathan; Lefebvre, Michael; McMahon, Tom J.; Miller, Douglas; Rahmer, Gustavo; Sosa, Richard; Taylor, Gregory; Vogel, Conrad; Zhang, Xianyu

    2016-07-01

    Vertical profiles of the atmospheric optical turbulence strength and velocity is of critical importance for simulating, designing, and operating the next generation of instruments for the European Extremely Large Telescope. Many of these instruments are already well into the design phase meaning these profies are required immediately to ensure they are optimised for the unique conditions likely to be observed. Stereo-SCIDAR is a generalised SCIDAR instrument which is used to characterise the profile of the atmospheric optical turbulence strength and wind velocity using triangulation between two optical binary stars. Stereo-SCIDAR has demonstrated the capability to resolve turbulent layers with the required vertical resolution to support wide-field ELT instrument designs. These high resolution atmospheric parameters are critical for design studies and statistical evaluation of on-sky performance under real conditions. Here we report on the new Stereo-SCIDAR instrument installed on one of the Auxillary Telescope ports of the Very Large Telescope array at Cerro Paranal. Paranal is located approximately 20 km from Cerro Armazones, the site of the E-ELT. Although the surface layer of the turbulence will be different for the two sites due to local geography, the high-altitude resolution profiles of the free atmosphere from this instrument will be the most accurate available for the E-ELT site. In addition, these unbiased and independent profiles are also used to further characterise the site of the VLT. This enables instrument performance calibration, optimisation and data analysis of, for example, the ESO Adaptive Optics facility and the Next Generation Transit Survey. It will also be used to validate atmospheric models for turbulence forecasting. We show early results from the commissioning and address future implications of the results.

  6. A survey on adaptive engine technology for serious games

    Science.gov (United States)

    Rasim, Langi, Armein Z. R.; Munir, Rosmansyah, Yusep

    2016-02-01

    Serious Games has become a priceless tool in learning because it can simulate abstract concept to appear more realistic. The problem faced is that the players have different ability in playing the games. This causes the players to become frustrated if the game is too difficult or to get bored if it is too easy. Serious games have non-player character (NPC) in it. The NPC should be able to adapt to the players in such a way so that the players can feel comfortable in playing the games. Because of that, serious games development must involve an adaptive engine, which is by applying a learning machine that can adapt to different players. The development of adaptive engine can be viewed in terms of the frameworks and the algorithms. Frameworks include rules based, plan based, organization description based, proficiency of player based, and learning style and cognitive state based. Algorithms include agents based and non-agent based

  7. The numerical simulation tool for the MAORY multiconjugate adaptive optics system

    Science.gov (United States)

    Arcidiacono, C.; Schreiber, L.; Bregoli, G.; Diolaiti, E.; Foppiani, I.; Agapito, G.; Puglisi, A.; Xompero, M.; Oberti, S.; Cosentino, G.; Lombini, M.; Butler, R. C.; Ciliegi, P.; Cortecchia, F.; Patti, M.; Esposito, S.; Feautrier, P.

    2016-07-01

    The Multiconjugate Adaptive Optics RelaY (MAORY) is and Adaptive Optics module to be mounted on the ESO European-Extremely Large Telescope (E-ELT). It is an hybrid Natural and Laser Guide System that will perform the correction of the atmospheric turbulence volume above the telescope feeding the Multi-AO Imaging Camera for Deep Observations Near Infrared spectro-imager (MICADO). We developed an end-to-end Monte- Carlo adaptive optics simulation tool to investigate the performance of a the MAORY and the calibration, acquisition, operation strategies. MAORY will implement Multiconjugate Adaptive Optics combining Laser Guide Stars (LGS) and Natural Guide Stars (NGS) measurements. The simulation tool implement the various aspect of the MAORY in an end to end fashion. The code has been developed using IDL and use libraries in C++ and CUDA for efficiency improvements. Here we recall the code architecture, we describe the modeled instrument components and the control strategies implemented in the code.

  8. The numerical simulation tool for the MAORY multiconjugate adaptive optics system

    CERN Document Server

    Arcidiacono, Carmelo; Bregoli, Giovanni; Diolaiti, Emiliano; Foppiani, Italo; Agapito, Guido; Puglisi, Alfio; Xompero, Marco; Oberti, Sylvain; Cosentino, Giuseppe; Lombini, Matteo; Butler, Chris R; Ciliegi, Paolo; Cortecchia, Fausto; Patti, Mauro; Esposito, Simone; Feautrier, Philippe

    2016-01-01

    The Multiconjugate Adaptive Optics RelaY (MAORY) is and Adaptive Optics module to be mounted on the ESO European-Extremely Large Telescope (E-ELT). It is a hybrid Natural and Laser Guide System that will perform the correction of the atmospheric turbulence volume above the telescope feeding the Multi-AO Imaging Camera for Deep Observations Near Infrared spectro-imager (MICADO). We developed an end-to-end Monte- Carlo adaptive optics simulation tool to investigate the performance of a the MAORY and the calibration, acquisition, operation strategies. MAORY will implement Multiconjugate Adaptive Optics combining Laser Guide Stars (LGS) and Natural Guide Stars (NGS) measurements. The simulation tool implements the various aspect of the MAORY in an end to end fashion. The code has been developed using IDL and uses libraries in C++ and CUDA for efficiency improvements. Here we recall the code architecture, we describe the modeled instrument components and the control strategies implemented in the code.

  9. Experimental Adaptive Digital Performance Monitoring for Optical DP-QPSK Coherent Receiver

    DEFF Research Database (Denmark)

    Borkowski, Robert; Zhang, Xu; Zibar, Darko;

    2011-01-01

    We report on a successful experimental demonstration of a digital optical performance monitoring (OPM) yielding satisfactory estimation accuracy along with adaptive impairment equalization. No observable penalty is measured when equalizer is driven by monitoring module....

  10. An Introduction to the E-ELT Instrumentation and Post-focal Adaptive Optics Module Studies

    Science.gov (United States)

    D'Odorico, S.; Ramsay, S.; Hubin, N.; Gonzalez, J. C.; Zerbi, F. M.

    2010-06-01

    The following eleven articles provide short summaries of the conceptual design studies for the European Extremely Large Telescope instruments and post-focal adaptive optics modules. The background and scope of these studies is outlined in this introduction.

  11. Robo-AO: An Autonomous Laser Adaptive Optics and Science System

    Science.gov (United States)

    Baranec, Christoph; Riddle, Reed; Ramaprakash, A. N.; Law, Nicholas; Tendulkar, Shriharsh; Kulkarni, Shrinivas; Dekany, Richard; Bui, Khanh; Davis, Jack; Zolkower, Jeff; Fucik, Jason; Burse, Mahesh; Das, Hillol; Chordia, Pravin; Kasliwal, Mansi; Ofek, Eran; Morton, Timothy; Johnson, John

    2011-07-01

    Robo-AO, a fully autonomous, laser guide star adaptive optics and science system, is being commissioned at Palomar Observatory's 60-inch telescope. Here we discuss the instrument, scientific goals and results of initial on-sky operation.

  12. Robo-AO: An Autonomous Laser Adaptive Optics and Science System

    CERN Document Server

    Baranec, Christoph; Ramaprakash, A N; Law, Nicholas; Tendulkar, Shriharsh; Kulkarni, Shrinivas; Dekany, Richard; Bui, Khanh; Davis, Jack; Zolkower, Jeff; Fucik, Jason; Burse, Mahesh; Das, Hillol; Chordia, Pravin; Kasliwal, Mansi; Ofek, Eran; Morton, Timothy; Johnson, John

    2012-01-01

    Robo-AO, a fully autonomous, laser guide star adaptive optics and science system, is being commissioned at Palomar Observatory's 60-inch telescope. Here we discuss the instrument, scientific goals and results of initial on-sky operation.

  13. Adaptive Integrated Optical Bragg Grating in Semiconductor Waveguide Suitable for Optical Signal Processing

    Science.gov (United States)

    Moniem, T. A.

    2016-05-01

    This article presents a methodology for an integrated Bragg grating using an alloy of GaAs, AlGaAs, and InGaAs with a controllable refractive index to obtain an adaptive Bragg grating suitable for many applications on optical processing and adaptive control systems, such as limitation and filtering. The refractive index of a Bragg grating is controlled by using an external electric field for controlling periodic modulation of the refractive index of the active waveguide region. The designed Bragg grating has refractive indices programmed by using that external electric field. This article presents two approaches for designing the controllable refractive indices active region of a Bragg grating. The first approach is based on the modification of a planar micro-strip structure of the iGaAs traveling wave as the active region, and the second is based on the modification of self-assembled InAs/GaAs quantum dots of an alloy from GaAs and InGaAs with a GaP traveling wave. The overall design and results are discussed through numerical simulation by using the finite-difference time-domain, plane wave expansion, and opto-wave simulation methods to confirm its operation and feasibility.

  14. Wavefront sensorless adaptive optics versus sensor-based adaptive optics for in vivo fluorescence retinal imaging (Conference Presentation)

    Science.gov (United States)

    Wahl, Daniel J.; Zhang, Pengfei; Jian, Yifan; Bonora, Stefano; Sarunic, Marinko V.; Zawadzki, Robert J.

    2017-02-01

    Adaptive optics (AO) is essential for achieving diffraction limited resolution in large numerical aperture (NA) in-vivo retinal imaging in small animals. Cellular-resolution in-vivo imaging of fluorescently labeled cells is highly desirable for studying pathophysiology in animal models of retina diseases in pre-clinical vision research. Currently, wavefront sensor-based (WFS-based) AO is widely used for retinal imaging and has demonstrated great success. However, the performance can be limited by several factors including common path errors, wavefront reconstruction errors and an ill-defined reference plane on the retina. Wavefront sensorless (WFS-less) AO has the advantage of avoiding these issues at the cost of algorithmic execution time. We have investigated WFS-less AO on a fluorescence scanning laser ophthalmoscopy (fSLO) system that was originally designed for WFS-based AO. The WFS-based AO uses a Shack-Hartmann WFS and a continuous surface deformable mirror in a closed-loop control system to measure and correct for aberrations induced by the mouse eye. The WFS-less AO performs an open-loop modal optimization with an image quality metric. After WFS-less AO aberration correction, the WFS was used as a control of the closed-loop WFS-less AO operation. We can easily switch between WFS-based and WFS-less control of the deformable mirror multiple times within an imaging session for the same mouse. This allows for a direct comparison between these two types of AO correction for fSLO. Our results demonstrate volumetric AO-fSLO imaging of mouse retinal cells labeled with GFP. Most significantly, we have analyzed and compared the aberration correction results for WFS-based and WFS-less AO imaging.

  15. Estimation of Satellite Orientation from Space Surveillance Imagery Measured with an Adaptive Optics Telescope

    Science.gov (United States)

    1996-12-01

    SATELLITE ORIENTATION FROM SPACE SURVEILLANCE IMAGERY MEASURED WITH AN ADAPTIVE OPTICS TELESCOPE THESIS Gregory E. Wood Lieutenant, USAF AFIT/GSO/ENP...the official policy or position of the Department of Defense or the U. S. Government. AFIT/GSO/ENP/96D-02 ESTIMATION OF SATELLITE ORIENTATION FROM...surveillance operations. xii ESTIMATION OF SATELLITE ORIENTATION FROM SPACE SURVEILLANCE IMAGERY MEASURED WITH AN ADAPTIVE OPTICS TELESCOPE

  16. 自适应光传送网%Adaptive Optical Transport Network

    Institute of Scientific and Technical Information of China (English)

    王加莹; 赵继军; 刘赛

    2005-01-01

    提出未来光网络的智能化特征,包括连接智能化、业务智能化和传输自适应三个方面.这几个方面的特征将成为未来自适应光传送网的标志.%Intelligent features of future optical transport self-adaptation' ,which will construct an integrated earmark of future self-adaptive optical transport network.

  17. SHARDS: an optical spectro-photometric survey of distant galaxies

    CERN Document Server

    Perez-Gonzalez, Pablo G; Barro, Guillermo; Villar, Victor; Cardiel, Nicolas; Ferreras, Ignacio; Rodriguez-Espinosa, Jose Miguel; Alonso-Herrero, Almudena; Balcells, Marc; Cenarro, Javier; Cepa, Jordi; Charlot, Stephane; Cimatti, Andrea; Conselice, Christopher J; Daddi, Emmanuele; Donley, Jennifer; Elbaz, David; Espino, Nestor; Gallego, Jesus; Gobat, R; Gonzalez-Martin, Omaira; Guzman, Rafael; Hernan-Caballero, Antonio; Muñoz-Tuñon, Casiana; Renzini, Alvio; Zaurin, Javier Rodriguez; Tresse, Laurence; Trujillo, Ignacio; Zamorano, Jaime

    2012-01-01

    (Abridged) We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out with GTC/OSIRIS. SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field (130 arcmin^2) at wavelengths 500 to 950 nm and using 24 contiguous medium-band filters (spectral resolution R 50). The data reach 26.5 mag (>3-sigma level) with sub-arcsec seeing in all bands. SHARDS main goal is obtaining accurate physical properties of interm- and high-z galaxies using well-sampled optical SEDs with sufficient spectral resolution to measure absorption and emission features. Among the different populations of high-z galaxies, SHARDS principal targets are massive quiescent galaxies at z>1. In this paper, we outline the observational strategy and include a detailed discussion of the special reduction and calibration procedures applied to the GTC/OSIRIS data. We present science demonstration results about the detection and study of emission-line galaxies (star-forming and AGN) ...

  18. VARIABILITY OF OPTICAL COUNTERPARTS IN THE CHANDRA GALACTIC BULGE SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Britt, C. T.; Hynes, R. I.; Johnson, C. B.; Baldwin, A.; Collazzi, A.; Gossen, L. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States); Jonker, P. G.; Torres, M. A. P. [SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands); Nelemans, G. [Department of Astrophysics, IMAPP, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen (Netherlands); Maccarone, T. [Department of Physics, Texas Tech University, Box 41051, Science Building, Lubbock, TX 79409-1051 (United States); Steeghs, D.; Greiss, S. [Astronomy and Astrophysics, Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Heinke, C. [Department of Physics, University of Alberta, CCIS 4-183, Edmonton, AB T6G 2E1 (Canada); Bassa, C. G. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Villar, A. [Department of Physics, Massachussettes Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307 (United States); Gabb, M. [Department of Physics, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991 (United States)

    2014-09-01

    We present optical light curves of variable stars consistent with the positions of X-ray sources identified with the Chandra X-ray Observatory for the Chandra Galactic Bulge Survey (GBS). Using data from the Mosaic-II instrument on the Blanco 4 m Telescope at CTIO, we gathered time-resolved photometric data on timescales from ∼2 hr to 8 days over the 3/4 of the X-ray survey containing sources from the initial GBS catalog. Among the light curve morphologies we identify are flickering in interacting binaries, eclipsing sources, dwarf nova outbursts, ellipsoidal variations, long period variables, spotted stars, and flare stars. Eighty-seven percent of X-ray sources have at least one potential optical counterpart. Twenty-seven percent of these candidate counterparts are detectably variable; a much greater fraction than expected for randomly selected field stars, which suggests that most of these variables are real counterparts. We discuss individual sources of interest, provide variability information on candidate counterparts, and discuss the characteristics of the variable population.

  19. The Subaru/XMM-Newton Deep Survey (SXDS) - V. Optically Faint Variable Object Survey

    CERN Document Server

    Morokuma, Tomoki; Yasuda, Naoki; Akiyama, Masayuki; Sekiguchi, Kazuhiro; Furusawa, Hisanori; Ueda, Yoshihiro; Totani, Tomonori; Oda, Takeshi; Nagao, Tohru; Kashikawa, Nobunari; Murayama, Takashi; Ouchi, Masami; Watson, Mike G; Richmond, Michael W; Lidman, Christopher; Perlmutter, Saul; Spadafora, Anthony L; Aldering, Greg; Wang, Lifan; Hook, Isobel M; Knop, Rob A

    2007-01-01

    We present our survey for optically faint variable objects using multi-epoch (8-10 epochs over 2-4 years) $i'$-band imaging data obtained with Subaru Suprime-Cam over 0.918 deg$^2$ in the Subaru/XMM-Newton Deep Field (SXDF). We found 1040 optically variable objects by image subtraction for all the combinations of images at different epochs. This is the first statistical sample of variable objects at depths achieved with 8-10m class telescopes or HST. The detection limit for variable components is $i'_{\\rm{vari}}\\sim25.5$ mag. These variable objects were classified into variable stars, supernovae (SNe), and active galactic nuclei (AGN), based on the optical morphologies, magnitudes, colors, and optical-mid-infrared colors of the host objects, spatial offsets of variable components from the host objects, and light curves. Detection completeness was examined by simulating light curves for periodic and irregular variability. We detected optical variability for $36\\pm2%$ ($51\\pm3%$ for a bright sample with $i'150$...

  20. High resolution mesospheric sodium properties for adaptive optics applications

    Science.gov (United States)

    Pfrommer, T.; Hickson, P.

    2014-05-01

    Context. The performance of laser guide star adaptive optics (AO) systems for large optical and infrared telescopes is affected by variability of the sodium layer, located at altitudes between 80 and 120 km in the upper mesosphere and lower thermosphere. The abundance and density structure of the atomic sodium found in this region is subject to local and global weather effects, planetary and gravity waves and magnetic storms, and is variable on time scales down to tens of milliseconds, a range relevant to AO. Aims: It is therefore important to characterize the structure and dynamical evolution of the sodium region on small, as well as large spatial and temporal scales. Parameters of particular importance for AO are the mean sodium altitude, sodium layer width and the temporal power spectrum of the centroid altitude. Methods: We have conducted a three-year campaign employing a high-resolution lidar system installed on the 6-m Large Zenith Telescope (LZT) located near Vancouver, Canada. During this period, 112 nights of useful data were obtained. Results: The vertical density profile of atomic sodium shows remarkable structure and variability. Smooth Gaussian-shaped profiles rarely occur. Multiple internal layers are frequently found. These layers often have sharp lower edges, with scale heights of just a few hundred meters, and tend to drift downwards at a typical rate of one kilometer every two to three hours. Individual layers can persist for many hours, but their density and internal structure can be highly variable. Sporadic layers are seen reaching peak densities several times the average, often in just a few minutes. Coherent vertical oscillations are often found, typically extending over tens of kilometers in altitude. Regions of turbulence are evident and Kelvin-Helmholtz instability are sometimes seen. The mean value of the centroid altitude is found to be 90.8 ± 0.1 km. The sodium layer width was determined by computing the altitude range that contains a

  1. [Spanish adaptation and factor structure of the Denison Organizational Culture Survey].

    Science.gov (United States)

    Bonavia, Tomás; Prado Gasco, Vicente J; Barberá Tomás, David

    2009-11-01

    This article presents a Spanish adaptation of the Denison Organizational Culture Survey, a questionnaire designed to evaluate organizational culture. This survey consists of 60 items, grouped in 12 subscales, which identify 4 cultural dimensions. These dimensions have been widely studied and their influence in organizational effectiveness has been accepted. This adaptation was applied to 488 participants, and analysed with confirmatory factor analysis. Results show adequate psychometric properties, so it can be concluded that the Spanish adaptation almost completely replicates the structure of the original version in English.

  2. A survey on object detection in optical remote sensing images

    Science.gov (United States)

    Cheng, Gong; Han, Junwei

    2016-07-01

    Object detection in optical remote sensing images, being a fundamental but challenging problem in the field of aerial and satellite image analysis, plays an important role for a wide range of applications and is receiving significant attention in recent years. While enormous methods exist, a deep review of the literature concerning generic object detection is still lacking. This paper aims to provide a review of the recent progress in this field. Different from several previously published surveys that focus on a specific object class such as building and road, we concentrate on more generic object categories including, but are not limited to, road, building, tree, vehicle, ship, airport, urban-area. Covering about 270 publications we survey (1) template matching-based object detection methods, (2) knowledge-based object detection methods, (3) object-based image analysis (OBIA)-based object detection methods, (4) machine learning-based object detection methods, and (5) five publicly available datasets and three standard evaluation metrics. We also discuss the challenges of current studies and propose two promising research directions, namely deep learning-based feature representation and weakly supervised learning-based geospatial object detection. It is our hope that this survey will be beneficial for the researchers to have better understanding of this research field.

  3. High-speed adaptive interferometer for optical coherence-domain reflectometry through turbid media.

    Science.gov (United States)

    Peng, L; Yu, P; Nolte, D D; Melloch, M R

    2003-03-15

    Two-wave mixing in a dynamic holographic film acts as the adaptive beam combiner in a short-coherence interferometer that performs optical coherence-domain reflectometry (OCDR) through turbid media. This approach combines the high spatial resolution and sensitivity of coherence-domain reflectometry with photorefractive quantum-well-based adaptive homodyne detection. A depth resolution of 28 microm and penetration through 16 mean free paths in a turbid medium have been obtained in this adaptive OCDR application.

  4. Validation of Optical Turbulence Simulations from a Numerical Weather Prediction Model in Support of Adaptive Optics Design

    Science.gov (United States)

    Alliss, R.; Felton, B.

    the vast lava fields which characterize the Big Island to the shoreline have a large impact on turbulence generation. The same turbulence characteristics are also present in the simulations on the Southeastern face of Haleakala. Turbulence is greatest during the daytime when the lava fields produce tremendous heat fluxes. Good agreement is found when the WRF simulations are compared to in situ data taken from the Advanced Technology Solar Telescope (ATST) Site Survey Working Group at the Mees Solar Observatory on Haleakala. The ATST used a solar DIMM instrument; therefore comparisons were limited to daytime. Both the WRF simulations and ATST showed ro values bottoming out in the 3-4 cm range during daytime. Analysis of the horizontal path between Haleakala and Mauna Loa show minimum ro dropping below 1 cm during the peak heating of the day. We are awaiting horizontal observations of Cn2 to become available to continue the validation exercises. Results of these analyses are assisting communication engineers in developing state of the art adaptive optic designs. Detailed results of this study will be presented at the conference.

  5. Three dimensional laser microfabrication in diamond using a dual adaptive optics system.

    Science.gov (United States)

    Simmonds, Richard D; Salter, Patrick S; Jesacher, Alexander; Booth, Martin J

    2011-11-21

    Femtosecond laser fabrication of controlled three dimensional structures deep in the bulk of diamond is facilitated by a dual adaptive optics system. A deformable mirror is used in parallel with a liquid crystal spatial light modulator to compensate the extreme aberrations caused by the refractive index mismatch between the diamond and the objective immersion medium. It is shown that aberration compensation is essential for the generation of controlled micron-scale features at depths greater than 200 μm, and the dual adaptive optics approach demonstrates increased fabrication efficiency relative to experiments using a single adaptive element.

  6. Keck Adaptive Optics Observations of Neptune's Ring and Satellite Keck Adaptive Optics Observations of Neptune's Ring and Satellite System

    Science.gov (United States)

    de Pater, I.; Gibbard, S.; Martin, S.; Marchis, F.; Roe, H. G.; Macintosh, B.

    2003-05-01

    We observed Neptune, its satellites and ring system on UT 27 and 28 July 2002, with NIRC2 on the 10-m Keck II telescope at 2.2 micron. The total field of view was 10". Each image was integrated for 1 minute; on the first day we had a total of 18 frames, and 33 images on the second day, each spread out over a time interval of 1-2 hours. The complete Adams and Le Verrier rings are visible on each day, after combining all images. In the regions away from the ring arcs, we find that the Le Verrier ring is brighter (up to 20-40%) than the Adams ring. The ring arcs are readily apparent in combinations of the data that take into account Keplerian motion. The ring arc positions are in close agreement with Nicholson et al's (1995) result, as in HST/NICMOS images (Dumas et al. 2002). The Egalite ring has broadened even more since observed with HST/NICMOS in 1998, and is clearly the brightest ring arc. Liberte has decreased in intensity since Voyager and NICMOS. Courage was extremely faint in our images. The satellites Proteus, Larissa, Galatea and Despina are easily seen on individual frames. Thalassa is detected after properly shifting/rotating and adding several frames. This is the first time since the Voyager flybys that Thalassa is detected. Preliminary astrometric measurements suggest the satellites Larissa and Galathea, relative to Proteus, to be off from their nominal (JPL Horizons) positions by 0.3", and Despina by 0.1". Recent results indicate that Proteus is offset by 0.1" compared to Triton (Martins et al. 2003). Preliminary I/F values are 0.06 for Proteus, 0.045 for Larissa and Galatea, and 0.03 for Despina and Thalassa. These observations were supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST-9876783

  7. Deriving comprehensive error breakdown for wide field adaptive optics systems using end-to-end simulations

    Science.gov (United States)

    Ferreira, F.; Gendron, E.; Rousset, G.; Gratadour, D.

    2016-07-01

    The future European Extremely Large Telescope (E-ELT) adaptive optics (AO) systems will aim at wide field correction and large sky coverage. Their performance will be improved by using post processing techniques, such as point spread function (PSF) deconvolution. The PSF estimation involves characterization of the different error sources in the AO system. Such error contributors are difficult to estimate: simulation tools are a good way to do that. We have developed in COMPASS (COMputing Platform for Adaptive opticS Systems), an end-to-end simulation tool using GPU (Graphics Processing Unit) acceleration, an estimation tool that provides a comprehensive error budget by the outputs of a single simulation run.

  8. Ingredients of Adaptability: A Survey of Reconfigurable Processors

    Directory of Open Access Journals (Sweden)

    Anupam Chattopadhyay

    2013-01-01

    Full Text Available For a design to survive unforeseen physical effects like aging, temperature variation, and/or emergence of new application standards, adaptability needs to be supported. Adaptability, in its complete strength, is present in reconfigurable processors, which makes it an important IP in modern System-on-Chips (SoCs. Reconfigurable processors have risen to prominence as a dominant computing platform across embedded, general-purpose, and high-performance application domains during the last decade. Significant advances have been made in many areas such as, identifying the advantages of reconfigurable platforms, their modeling, implementation flow and finally towards early commercial acceptance. This paper reviews these progresses from various perspectives with particular emphasis on fundamental challenges and their solutions. Empowered with the analysis of past, the future research roadmap is proposed.

  9. Imaging human retinal pigment epithelium cells using adaptive optics optical coherence tomography

    Science.gov (United States)

    Liu, Zhuolin; Kocaoglu, Omer P.; Turner, Timothy L.; Miller, Donald T.

    2016-03-01

    Retinal pigment epithelium (RPE) cells are vital to health of the outer retina, but are often compromised in ageing and major ocular diseases that lead to blindness. Early manifestation of RPE disruption occurs at the cellular level, and while biomarkers at this scale hold considerable promise, RPE cells have proven extremely challenging to image in the living human eye. We present a novel method based on optical coherence tomography (OCT) equipped with adaptive optics (AO) that overcomes the associated technical obstacles. The method takes advantage of the 3D resolution of AO-OCT, but more critically sub-cellular segmentation and registration that permit organelle motility to be used as a novel contrast mechanism. With this method, we successfully visualized RPE cells and characterized their 3D reflectance profile in every subject and retinal location (3° and 7° temporal to the fovea) imaged to date. We have quantified RPE packing geometry in terms of cell density, cone-to-RPE ratio, and number of nearest neighbors using Voronoi and power spectra analyses. RPE cell density (cells/mm2) showed no significant difference between 3° (4,892+/-691) and 7° (4,780+/-354). In contrast, cone-to- RPE ratio was significantly higher at 3° (3.88+/-0.52:1) than 7° (2.31+/- 0.23:1). Voronoi analysis also showed most RPE cells have six nearest neighbors, which was significantly larger than the next two most prevalent associations: five and seven. Averaged across the five subjects, prevalence of cells with six neighbors was 51.4+/-3.58% at 3°, and 54.58+/-3.01% at 7°. These results are consistent with histology and in vivo studies using other imaging modalities.

  10. Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics.

    Science.gov (United States)

    Kocaoglu, Omer P; Cense, Barry; Jonnal, Ravi S; Wang, Qiang; Lee, Sangyeol; Gao, Weihua; Miller, Donald T

    2011-08-15

    Early detection of axonal tissue loss in retinal nerve fiber layer (RNFL) is critical for effective treatment and management of diseases such as glaucoma. This study aims to evaluate the capability of ultrahigh-resolution optical coherence tomography with adaptive optics (UHR-AO-OCT) for imaging the RNFL axonal bundles (RNFBs) with 3×3×3μm(3) resolution in the eye. We used a research-grade UHR-AO-OCT system to acquire 3°×3° volumes in four normal subjects and one subject with an arcuate retinal nerve fiber layer defect (n=5; 29-62years). Cross section (B-scans) and en face (C-scan) slices extracted from the volumes were used to assess visibility and size distribution of individual RNFBs. In one subject, we reimaged the same RNFBs twice over a 7month interval and compared bundle width and thickness between the two imaging sessions. Lastly we compared images of an arcuate RNFL defect acquired with UHR-AO-OCT and commercial OCT (Heidelberg Spectralis). Individual RNFBs were distinguishable in all subjects at 3° retinal eccentricity in both cross-sectional and en face views (width: 30-50μm, thickness: 10-15μm). At 6° retinal eccentricity, RNFBs were distinguishable in three of the five subjects in both views (width: 30-45μm, thickness: 20-40μm). Width and thickness RNFB measurements taken 7months apart were strongly correlated (p<0.0005). Mean difference and standard deviation of the differences between the two measurement sessions were -0.1±4.0μm (width) and 0.3±1.5μm (thickness). UHR-AO-OCT outperformed commercial OCT in terms of clarity of the microscopic retina. To our knowledge, these are the first measurements of RNFB cross section reported in the living human eye.

  11. Adaptive Optical Phase Estimation Using Time-Symmetric Quantum Smoothing

    CERN Document Server

    Wheatley, T A; Yonezawa, H; Nakane, D; Arao, H; Pope, D T; Ralph, T C; Wiseman, H M; Furusawa, A; Huntington, E H

    2009-01-01

    Quantum parameter estimation has many applications, from gravitational wave detection to quantum key distribution. We present the first experimental demonstration of the time-symmetric technique of quantum smoothing. We consider both adaptive and non-adaptive quantum smoothing, and show that both are better than their well-known time-asymmetric counterparts (quantum filtering). For the problem of estimating a stochastically varying phase shift on a coherent beam, our theory predicts that adaptive quantum smoothing (the best scheme) gives an estimate with a mean-square error up to $2\\sqrt{2}$ times smaller than that from non-adaptive quantum filtering (the standard quantum limit). The experimentally measured improvement is $2.24 \\pm 0.14$.

  12. Adaptive optics for in vivo two-photon calcium imaging of neuronal networks

    Science.gov (United States)

    Meimon, Serge; Conan, Jean-Marc; Mugnier, Laurent M.; Michau, Vincent; Cossart, Rosa; Malvache, Arnaud

    2014-03-01

    The landscape of biomedical research in neuroscience has changed dramatically in recent years as a result of spectacular progress in dynamic microscopy. However, the optical accessibility of deep brain structures or deeper regions of the surgically exposed hippocampus (a few 100 microns typically) remains limited, due to volumic aberrations created by the sample inhomogeneities. Adaptive optics can correct for these aberrations. Our goal is to realize a novel adaptive optics module dedicated to in vivo two-photon calcium imaging of the hippocampus. The key issue in adaptive optics is the ability to perform an accurate and reliable wavefront sensing. In two- photon microscopy indirect methods are required. Two families of approaches have been proposed so far, the modal sensorless technique and a method based on pupil segmentation. We present here a formal comparison of these approaches, in particular as a function of the amount of aberrations.

  13. High-Resolution Adaptive Optics Test-Bed for Vision Science

    Energy Technology Data Exchange (ETDEWEB)

    Wilks, S C; Thomspon, C A; Olivier, S S; Bauman, B J; Barnes, T; Werner, J S

    2001-09-27

    We discuss the design and implementation of a low-cost, high-resolution adaptive optics test-bed for vision research. It is well known that high-order aberrations in the human eye reduce optical resolution and limit visual acuity. However, the effects of aberration-free eyesight on vision are only now beginning to be studied using adaptive optics to sense and correct the aberrations in the eye. We are developing a high-resolution adaptive optics system for this purpose using a Hamamatsu Parallel Aligned Nematic Liquid Crystal Spatial Light Modulator. Phase-wrapping is used to extend the effective stroke of the device, and the wavefront sensing and wavefront correction are done at different wavelengths. Issues associated with these techniques will be discussed.

  14. Optical-SZE Scaling Relations for DES Optically Selected Clusters within the SPT-SZ Survey

    CERN Document Server

    Saro, A; Mohr, J; Rozo, E; Benson, B A; Dodelson, S; Rykoff, E S; Bleem, L; Abbott, T M C; Abdalla, F B; Allen, S; Annis, J; Benoit-Levy, A; Brooks, D; Burke, D L; Capasso, R; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Chiu, I; Crawford, T M; Cunha, C E; D'Andrea, C B; da Costa, L N; Desai, S; Dietrich, J P; Evrard, A E; Neto, A Fausti; Flaugher, B; Fosalba, P; Frieman, J; Gangkofner, C; Gaztanaga, E; Gerdes, D W; Giannantonio, T; Grandis, S; Gruen, D; Gruendl, R A; Gupta, N; Gutierrez, G; Holzapfel, W L; James, D J; Kuehn, K; Kuropatkin, N; Lima, M; Marshall, J L; McDonald, M; Melchior, P; Menanteau, F; Miquel, R; Ogando, R; Plazas, A A; Rapetti, D; Reichardt, C L; Reil, K; Romer, A K; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Soergel, B; Strazzullo, V; Suchyta, E; Swanson, M E C; Tarle, G; Thomas, D; Vikram, V; Walker, A R; Zenteno, A

    2016-01-01

    We study the Sunyaev-Zel'dovich effect (SZE) signature in South Pole Telescope (SPT) data for an ensemble of 719 optically identified galaxy clusters selected from 124.6 deg$^2$ of the Dark Energy Survey (DES) science verification data, detecting a stacked SZE signal down to richness $\\lambda\\sim20$. The SZE signature is measured using matched-filtered maps of the 2500 deg$^2$ SPT-SZ survey at the positions of the DES clusters, and the degeneracy between SZE observable and matched-filter size is broken by adopting as priors SZE and optical mass-observable relations that are either calibrated using SPT selected clusters or through the Arnaud et al. (2010, A10) X-ray analysis. We measure the SPT signal to noise $\\zeta$-$\\lambda$, relation and two integrated Compton-$y$ $Y_\\textrm{500}$-$\\lambda$ relations for the DES-selected clusters and compare these to model expectations accounting for the SZE-optical center offset distribution. For clusters with $\\lambda > 80$, the two SPT calibrated scaling relations are c...

  15. Adaptive optics OCT using 1060nm swept source and dual deformable lenses for human retinal imaging

    Science.gov (United States)

    Jian, Yifan; Lee, Sujin; Cua, Michelle; Miao, Dongkai; Bonora, Stefano; Zawadzki, Robert J.; Sarunic, Marinko V.

    2016-03-01

    Adaptive optics concepts have been applied to the advancement of biological imaging and microscopy. In particular, AO has also been very successfully applied to cellular resolution imaging of the retina, enabling visualization of the characteristic mosaic patterns of the outer retinal layers using flood illumination fundus photography, Scanning Laser Ophthalmoscopy (SLO), and Optical Coherence Tomography (OCT). Despite the high quality of the in vivo images, there has been a limited uptake of AO imaging into the clinical environment. The high resolution afforded by AO comes at the price of limited field of view and specialized equipment. The implementation of a typical adaptive optics imaging system results in a relatively large and complex optical setup. The wavefront measurement is commonly performed using a Hartmann-Shack Wavefront Sensor (HS-WFS) placed at an image plane that is optically conjugated to the eye's pupil. The deformable mirror is also placed at a conjugate plane, relaying the wavefront corrections to the pupil. Due to the sensitivity of the HS-WFS to back-reflections, the imaging system is commonly constructed from spherical mirrors. In this project, we present a novel adaptive optics OCT retinal imaging system with significant potential to overcome many of the barriers to integration with a clinical environment. We describe in detail the implementation of a compact lens based wavefront sensorless adaptive optics (WSAO) 1060nm swept source OCT human retinal imaging system with dual deformable lenses, and present retinal images acquired in vivo from research volunteers.

  16. Segmentation of the Optic Disc and Optic Cup Using Histogram Feature-Based Adaptive Threshold for Cup to Disk Ratio

    Directory of Open Access Journals (Sweden)

    Nugraha Gibran Satya

    2016-01-01

    Full Text Available Glaucoma is a condition of increased intraocular pressure within the eyes. Such increase then causes the damage on optic nerves as the organ bringing information to be processed in brain. One of the parameters to detect the glaucoma is the ratio between the optic cup and optic disc that can be identified through an examination towards the retinal fundus image of the patient. The ratio is obtained by firstly calculating the width of the area of the optic cup and the optic disc. This research was aimed to propose a method of the segmentation of the optic cup and optic disc with the adaptive threshold. The value of the adaptive threshold was obtained once calculating the mean value and standard deviation on the retinal fundus image of the patient. Before conducting the segmentation, the red component of the image would firstly be extracted followed by doing the contrast stretching. The last one was to perform the morphological operation such as closing and opening to remove the blood vessel to make the ratio calculation more accurate. This method has been tested in a number of retinal fundus images coming from DRISTHI-GS and RIM-ONE.

  17. [Adaptation of the Medical Office Survey on Patient Safety Culture (MOSPSC) tool].

    Science.gov (United States)

    Silvestre-Busto, C; Torijano-Casalengua, M L; Olivera-Cañadas, G; Astier-Peña, M P; Maderuelo-Fernández, J A; Rubio-Aguado, E A

    2015-01-01

    To adapt the Medical Office Survey on Patient Safety Culture (MOSPSC) Excel(®) tool for its use by Primary Care Teams of the Spanish National Public Health System. The process of translation and adaptation of MOSPSC from the Agency for Healthcare and Research in Quality (AHRQ) was performed in five steps: Original version translation, Conceptual equivalence evaluation, Acceptability and viability assessment, Content validity and Questionnaire test and response analysis, and psychometric properties assessment. After confirming MOSPSC as a valid, reliable, consistent and useful tool for assessing patient safety culture in our setting, an Excel(®) worksheet was translated and adapted in the same way. It was decided to develop a tool to analyze the "Spanish survey" and to keep it linked to the "Original version" tool. The "Spanish survey" comparison data are those obtained in a 2011 nationwide Spanish survey, while the "Original version" comparison data are those provided by the AHRQ in 2012. The translated and adapted tool and the analysis of the results from a 2011 nationwide Spanish survey are available on the website of the Ministry of Health, Social Services and Equality. It allows the questions which are decisive in the different dimensions to be determined, and it provides a comparison of the results with graphical representation. Translation and adaptation of this tool enables a patient safety culture in Primary Care in Spain to be more effectively applied. Copyright © 2014 SECA. Published by Elsevier Espana. All rights reserved.

  18. Interferometric velocity measurements through a fluctuating gas-liquid interface employing adaptive optics.

    Science.gov (United States)

    Büttner, Lars; Leithold, Christoph; Czarske, Jürgen

    2013-12-16

    Optical transmission through fluctuating interfaces of mediums with different refractive indexes is limited by the occurring distortions. Temporal fluctuations of such distortions deteriorate optical measurements. In order to overcome this shortcoming we propose the use of adaptive optics. For the first time, an interferometric velocity measurement technique with embedded adaptive optics is presented for flow velocity measurements through a fluctuating air-water interface. A low order distortion correction technique using a fast deformable mirror and a Hartmann-Shack camera with high frame rate is employed. The obtained high control bandwidth enables precise measurements also at fast fluctuating media interfaces. This methodology paves the way for several kinds of optical flow measurements in various complex environments.

  19. Optical-SZE scaling relations for DES optically selected clusters within the SPT-SZ Survey

    Science.gov (United States)

    Saro, A.; Bocquet, S.; Mohr, J.; Rozo, E.; Benson, B. A.; Dodelson, S.; Rykoff, E. S.; Bleem, L.; Abbott, T. M. C.; Abdalla, F. B.; Allen, S.; Annis, J.; Benoit-Lévy, A.; Brooks, D.; Burke, D. L.; Capasso, R.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Chiu, I.; Crawford, T. M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Dietrich, J. P.; Evrard, A. E.; Neto, A. Fausti; Flaugher, B.; Fosalba, P.; Frieman, J.; Gangkofner, C.; Gaztanaga, E.; Gerdes, D. W.; Giannantonio, T.; Grandis, S.; Gruen, D.; Gruendl, R. A.; Gupta, N.; Gutierrez, G.; Holzapfel, W. L.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lima, M.; Marshall, J. L.; McDonald, M.; Melchior, P.; Menanteau, F.; Miquel, R.; Ogando, R.; Plazas, A. A.; Rapetti, D.; Reichardt, C. L.; Reil, K.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Soergel, B.; Strazzullo, V.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Vikram, V.; Walker, A. R.; Zenteno, A.

    2017-07-01

    We study the Sunyaev-Zel'dovich effect (SZE) signature in South Pole Telescope (SPT) data for an ensemble of 719 optically identified galaxy clusters selected from 124.6 deg2 of the Dark Energy Survey (DES) science verification data, detecting a clear stacked SZE signal down to richness λ ˜ 20. The SZE signature is measured using matched-filtered maps of the 2500 deg2 SPT-SZ survey at the positions of the DES clusters, and the degeneracy between SZE observable and matched-filter size is broken by adopting as priors SZE and optical mass-observable relations that are either calibrated using SPT-selected clusters or through the Arnaud et al. (A10) X-ray analysis. We measure the SPT signal-to-noise ζ-λ relation and two integrated Compton-y Y500-λ relations for the DES-selected clusters and compare these to model expectations that account for the SZE-optical centre offset distribution. For clusters with λ > 80, the two SPT-calibrated scaling relations are consistent with the measurements, while for the A10-calibrated relation the measured SZE signal is smaller by a factor of 0.61 ± 0.12 compared to the prediction. For clusters at 20 compared to the prediction, with the SPT-calibrated scaling relations and larger λ clusters showing generally better agreement. We quantify the required corrections to achieve consistency, showing that there is a richness-dependent bias that can be explained by some combination of (1) contamination of the observables and (2) biases in the estimated halo masses. We also discuss particular physical effects associated with these biases, such as contamination of λ from line-of-sight projections or of the SZE observables from point sources, larger offsets in the SZE-optical centring or larger intrinsic scatter in the λ-mass relation at lower richnesses.

  20. Optical-SZE Scaling Relations for DES Optically Selected Clusters within the SPT-SZ Survey

    Energy Technology Data Exchange (ETDEWEB)

    Saro, A.; et al.

    2016-05-27

    We study the Sunyaev-Zel'dovich effect (SZE) signature in South Pole Telescope (SPT) data for an ensemble of 719 optically identified galaxy clusters selected from 124.6 deg$^2$ of the Dark Energy Survey (DES) science verification data, detecting a stacked SZE signal down to richness $\\lambda\\sim20$. The SZE signature is measured using matched-filtered maps of the 2500 deg$^2$ SPT-SZ survey at the positions of the DES clusters, and the degeneracy between SZE observable and matched-filter size is broken by adopting as priors SZE and optical mass-observable relations that are either calibrated using SPT selected clusters or through the Arnaud et al. (2010, A10) X-ray analysis. We measure the SPT signal to noise $\\zeta$-$\\lambda$, relation and two integrated Compton-$y$ $Y_\\textrm{500}$-$\\lambda$ relations for the DES-selected clusters and compare these to model expectations accounting for the SZE-optical center offset distribution. For clusters with $\\lambda > 80$, the two SPT calibrated scaling relations are consistent with the measurements, while for the A10-calibrated relation the measured SZE signal is smaller by a factor of $0.61 \\pm 0.12$ compared to the prediction. For clusters at $20 < \\lambda < 80$, the measured SZE signal is smaller by a factor of $\\sim$0.20-0.80 (between 2.3 and 10~$\\sigma$ significance) compared to the prediction, with the SPT calibrated scaling relations and larger $\\lambda$ clusters showing generally better agreement. We quantify the required corrections to achieve consistency, showing that there is a richness dependent bias that can be explained by some combination of contamination of the observables and biases in the estimated masses. We discuss possible physical effects, as contamination from line-of-sight projections or from point sources, larger offsets in the SZE-optical centering or larger scatter in the $\\lambda$-mass relation at lower richnesses.

  1. Analysis and simulation of aperture-sizing strategies with partial adaptive optics

    Science.gov (United States)

    Tyson, Robert K.

    1994-05-01

    The central core intensity of a stellar image observed by a ground-based telescope can be maximized by a judicious balancing of the adaptive optics system and the size of the telescope entrance aperture. For a given aperture, increasing the number of degrees of adaptive optics turbulence compensation will maximize the brightness of the central core. However, for an observatory using an adaptive optics system with a fixed number of degrees-of-freedom, the largest aperture available will not necessarily result in a maximized image central core. The negative effects of atmospheric turbulence, roughly proportional to e(superscript -(D/r(subscript o))(superscript 5/3)), cannot always be compensated by the increased light gathering ability of a larger aperture (proportional to D(superscript 2)). It is shown and verified through simulation that the optimum aperture diameter is a function of N(superscript p) r(subscript o) where N is the number of adaptive optics degrees of freedom and r(subscript o) is the seeing cell size. The simulations show that the exponent p is related to the control algorithm or, more precisely, the figure-of-merit used to drive the deformable mirror actuators. Optimizing the useful aperture of the telescope/adaptive optics system is a strategy that can make use of the variation in site seeing conditions and benefit the astronomer by increasing the available number of observable science objects or reducing the observing time.

  2. Quality evaluation of adaptive optical image based on DCT and Rényi entropy

    Science.gov (United States)

    Xu, Yuannan; Li, Junwei; Wang, Jing; Deng, Rong; Dong, Yanbing

    2015-04-01

    The adaptive optical telescopes play a more and more important role in the detection system on the ground, and the adaptive optical images are so many that we need find a suitable method of quality evaluation to choose good quality images automatically in order to save human power. It is well known that the adaptive optical images are no-reference images. In this paper, a new logarithmic evaluation method based on the use of the discrete cosine transform(DCT) and Rényi entropy for the adaptive optical images is proposed. Through the DCT using one or two dimension window, the statistical property of Rényi entropy for images is studied. The different directional Rényi entropy maps of an input image containing different information content are obtained. The mean values of different directional Rényi entropy maps are calculated. For image quality evaluation, the different directional Rényi entropy and its standard deviation corresponding to region of interest is selected as an indicator for the anisotropy of the images. The standard deviation of different directional Rényi entropy is obtained as the quality evaluation value for adaptive optical image. Experimental results show the proposed method that the sorting quality matches well with the visual inspection.

  3. Optomechanical analysis and design tool for adaptive x-ray optics

    Science.gov (United States)

    Michels, Gregory; Genberg, Victor

    2010-09-01

    Adaptive X-ray optics offer significant potential for new optical systems. An analysis and design tool for the optomechanical design of adaptive X-ray optics is presented. The key issues addressed are: 1) The processing of finite element nodal displacements for optical surface characterization is illustrated. 2) The fitting of Fourier-Legendre polynomials to the radial sag or surface normal displacements of near cylindrical optics is presented. 3) The use of 2D Legendre polynomials are presented as an alternative representation of mechanical displacements. 4) The analysis of adaptive X-ray optics requires the solution of actuator strokes required to minimize surface RMS. Issues include stroke limits and surface slope error minimization. 5) The number and placement of actuators can be optimized by using an embedded genetic selection algorithm. 6) The mirror structure and mounts may be optimized to minimize the adaptively corrected surface error while still satisfying all structural requirements. 7) The implementation of a Monte Carlo technique to predict the impact of random factors in the system such as actuator resolution or mount strain forces.

  4. Packetisation in Optical Packet Switch Fabrics using adaptive timeout values

    DEFF Research Database (Denmark)

    Mortensen, Brian Bach

    2006-01-01

    to the inter arrival rate at the individual VOQs. The remaining thresholds applies to the optical slot level inter arrival rate at the input and output line cards. If any measurements are beyond a given threshold, the higher timeout value is used. The proposed method can be used to make a trade-off between...... either because the timer reaches a specific timeout value, or because the optical packet is completely filled with segments. Only two distinct values of the timeout value are used. Which of the two timeout values to use, is selected by 3 different control thresholds. The first threshold level applies...

  5. Rise of the Machines: Automated Laser Guide Star Adaptive Optics Observations of Thousands of Objects with Robo-AO

    Science.gov (United States)

    Riddle, Reed L.; Baranec, C.; Law, N. M.; Tendulkar, S. P.; Ramaprakash, A. N.; Kulkarni, S. R.; Dekany, R.; Bui, K.; Burse, M.; Das, H.; Punnadi, S.; Chordia, P.

    2013-01-01

    Robo-AO is the first fully automated laser guide star adaptive optics instrument. Robo-AO has completed thousands of automated AO observations at the visible diffraction limit for several scientific programs during its first semester of science observations. These programs include: the Ultimate Binarity Survey to examine stellar binarity properties across the main sequence and beyond; a survey of 1,000 Kepler objects of interest; the multiplicity of solar type stars; and several programs for high precision astrometric observations. A new infrared camera is under development for Robo-AO, and a clone of the system is in the planning stages. This presentation will discuss the Robo-AO instrument capabilities, summarize the science programs undertaken, and discuss the future of Robo-AO.

  6. Computational adaptive optics for broadband interferometric tomography of tissues and cells

    Science.gov (United States)

    Adie, Steven G.; Mulligan, Jeffrey A.

    2016-03-01

    Adaptive optics (AO) can shape aberrated optical wavefronts to physically restore the constructive interference needed for high-resolution imaging. With access to the complex optical field, however, many functions of optical hardware can be achieved computationally, including focusing and the compensation of optical aberrations to restore the constructive interference required for diffraction-limited imaging performance. Holography, which employs interferometric detection of the complex optical field, was developed based on this connection between hardware and computational image formation, although this link has only recently been exploited for 3D tomographic imaging in scattering biological tissues. This talk will present the underlying imaging science behind computational image formation with optical coherence tomography (OCT) -- a beam-scanned version of broadband digital holography. Analogous to hardware AO (HAO), we demonstrate computational adaptive optics (CAO) and optimization of the computed pupil correction in 'sensorless mode' (Zernike polynomial corrections with feedback from image metrics) or with the use of 'guide-stars' in the sample. We discuss the concept of an 'isotomic volume' as the volumetric extension of the 'isoplanatic patch' introduced in astronomical AO. Recent CAO results and ongoing work is highlighted to point to the potential biomedical impact of computed broadband interferometric tomography. We also discuss the advantages and disadvantages of HAO vs. CAO for the effective shaping of optical wavefronts, and highlight opportunities for hybrid approaches that synergistically combine the unique advantages of hardware and computational methods for rapid volumetric tomography with cellular resolution.

  7. Adaptive Optics for EUV Lithography: Phase Retrieval for Wavefront Metrology

    NARCIS (Netherlands)

    Polo, A.

    2014-01-01

    In the semiconductor industry, optical lithography is presently the most widespread technology used to print a geometrical pattern on a semiconductor wafer. Because of the plans imposed by the International Technology Roadmap for Semiconductors (ITRS) for more powerful and smaller chips, new printin

  8. Adaptive Optics for EUV Lithography: Phase Retrieval for Wavefront Metrology

    NARCIS (Netherlands)

    Polo, A.

    2014-01-01

    In the semiconductor industry, optical lithography is presently the most widespread technology used to print a geometrical pattern on a semiconductor wafer. Because of the plans imposed by the International Technology Roadmap for Semiconductors (ITRS) for more powerful and smaller chips, new printin

  9. Elastic all-optical multi-hop interconnection in data centers with adaptive spectrum allocation

    Science.gov (United States)

    Hong, Yuanyuan; Hong, Xuezhi; Chen, Jiajia; He, Sailing

    2017-01-01

    In this paper, a novel flex-grid all-optical interconnect scheme that supports transparent multi-hop connections in data centers is proposed. An inter-rack all-optical multi-hop connection is realized with an optical loop employed at flex-grid wavelength selective switches (WSSs) in an intermediate rack rather than by relaying through optical-electric-optical (O-E-O) conversions. Compared with the conventional O-E-O based approach, the proposed all-optical scheme is able to off-load the traffic at intermediate racks, leading to a reduction of the power consumption and cost. The transmission performance of the proposed flex-grid multi-hop all-optical interconnect scheme with various modulation formats, including both coherently detected and directly detected approaches, are investigated by Monte-Carlo simulations. To enhance the spectrum efficiency (SE), number-of-hop adaptive bandwidth allocation is introduced. Numerical results show that the SE can be improved by up to 33.3% at 40 Gbps, and by up to 25% at 100 Gbps. The impact of parameters, such as targeted bit error rate (BER) level and insertion loss of components, on the transmission performance of the proposed approach are also explored. The results show that the maximum SE improvement of the adaptive approach over the non-adaptive one is enhanced with the decrease of the targeted BER levels and the component insertion loss.

  10. Development of a scalable generic platform for adaptive optics real time control

    CERN Document Server

    Surendran, Avinash; Ramaprakash, A N; Parihar, Padmakar

    2015-01-01

    The main objective of the present project is to explore the viability of an adaptive optics control system based exclusively on Field Programmable Gate Arrays (FPGAs), making strong use of their parallel processing capability. In an Adaptive Optics (AO) system, the generation of the Deformable Mirror (DM) control voltages from the Wavefront Sensor (WFS) measurements is usually through the multiplication of the wavefront slopes with a predetermined reconstructor matrix. The ability to access several hundred hard multipliers and memories concurrently in an FPGA allows performance far beyond that of a modern CPU or GPU for tasks with a well defined structure such as Adaptive Optics control. The target of the current project is to generate a signal for a real time wavefront correction, from the signals coming from a Wavefront Sensor, wherein the system would be flexible to accommodate all the current Wavefront Sensing techniques and also the different methods which are used for wavefront compensation. The system ...

  11. Laboratory comparison of coronagraphic concepts under dynamical seeing and high-order adaptive optics correction

    CERN Document Server

    Martinez, P; Kasper, M; Boccaletti, A; Dorrer, C; Baudrand, J

    2011-01-01

    The exoplanetary science through direct imaging and spectroscopy will largely expand with the forthcoming development of new instruments at the VLT (SPHERE), Gemini (GPI), Subaru (HiCIAO), and Palomar (Project 1640) observatories. All these ground-based adaptive optics instruments combine extremely high performance adaptive optics (XAO) systems correcting for the atmospheric turbulence with advanced starlight-cancellation techniques such as coronagraphy to deliver contrast ratios of about 10-6 to 10-7. While the past fifteen years have seen intensive research and the development of high-contrast coronagraph concepts, very few concepts have been tested under dynamical seeing conditions (either during sky observation or in a realistic laboratory environment). In this paper, we discuss the results obtained with four different coronagraphs -- phase and amplitude types -- on the High-Order Testbench (HOT), the adaptive optics facility developed at ESO. This facility emphasizes realistic conditions encountered at a...

  12. Adaptive, optical, radial basis function neural network for handwritten digit recognition

    Science.gov (United States)

    Foor, Wesley E.; Neifeld, Mark A.

    1995-11-01

    An adaptive, optical, radial basis function classifier for handwritten digit recognition is experimentally demonstrated. We describe a spatially multiplexed system that incorporates an on-line adaptation of weights and basis function widths to provide robustness to optical system imperfections and system noise. The optical system computes the Euclidean distances between a 100-dimensional input vector and 198 stored reference patterns in parallel by using dual vector-matrix multipliers and a contrast-reversing spatial light modulator. Software is used to emulate an electronic chip that performs the on-line learning of the weights and basis function widths. An experimental recognition rate of 92.7% correct out of 300 testing samples is achieved with the adaptive training, versus 31.0% correct for nonadaptive training. We compare the experimental results with a detailed computer model of the system in order to analyze the influence of various noise sources on the system performance.

  13. Sky coverage modeling for the whole sky for laser guide star multiconjugate adaptive optics.

    Science.gov (United States)

    Wang, Lianqi; Andersen, David; Ellerbroek, Brent

    2012-06-01

    The scientific productivity of laser guide star adaptive optics systems strongly depends on the sky coverage, which describes the probability of finding natural guide stars for the tip/tilt wavefront sensor(s) to achieve a certain performance. Knowledge of the sky coverage is also important for astronomers planning their observations. In this paper, we present an efficient method to compute the sky coverage for the laser guide star multiconjugate adaptive optics system, the Narrow Field Infrared Adaptive Optics System (NFIRAOS), being designed for the Thirty Meter Telescope project. We show that NFIRAOS can achieve more than 70% sky coverage over most of the accessible sky with the requirement of 191 nm total rms wavefront.

  14. Star formation properties and dynamics of Luminous Infrared Galaxies with adaptive optics

    CERN Document Server

    Vaisanen, Petri; Ryder, Stuart

    2009-01-01

    Near infrared adaptive optics observations are crucial to be able to interpret kinematic and dynamical data and study star formation properties within the often extremely dusty interacting luminous IR galaxies (LIRGs). NIR AO data are also needed to find supernovae in their bright and dusty central regions and to fully characterize the young stellar clusters found in these kinds of systems. We have used AO in the K-band to survey a sample of LIRGs at 0.1 arcsec (30 to 100 pc) resolution. The data are merged with SALT and AAT spectroscopic follow-up and HST and Spitzer archival imaging. The first AO detected SNe are reported as well as details of the first studied LIRGs. One LIRG showed an unexpected third component in the interaction, which moreover turned out to host the most active star formation. Another target showed evidence in the NIR of a very rare case of leading spiral arms, rotating in the same direction as the arms open.

  15. The Chandra Deep Field South as a test case for Global Multi Conjugate Adaptive Optics

    Science.gov (United States)

    Portaluri, E.; Viotto, V.; Ragazzoni, R.; Gullieuszik, M.; Bergomi, M.; Greggio, D.; Biondi, F.; Dima, M.; Magrin, D.; Farinato, J.

    2017-04-01

    The era of the next generation of giant telescopes requires not only the advent of new technologies but also the development of novel methods, in order to exploit fully the extraordinary potential they are built for. Global Multi Conjugate Adaptive Optics (GMCAO) pursues this approach, with the goal of achieving good performance over a field of view of a few arcmin and an increase in sky coverage. In this article, we show the gain offered by this technique to an astrophysical application, such as the photometric survey strategy applied to the Chandra Deep Field South as a case study. We simulated a close-to-real observation of a 500 × 500 arcsec2 extragalactic deep field with a 40-m class telescope that implements GMCAO. We analysed mock K-band images of 6000 high-redshift (up to z = 2.75) galaxies therein as if they were real to recover the initial input parameters. We attained 94.5 per cent completeness for source detection with SEXTRACTOR. We also measured the morphological parameters of all the sources with the two-dimensional fitting tools GALFIT. The agreement we found between recovered and intrinsic parameters demonstrates GMCAO as a reliable approach to assist extremely large telescope (ELT) observations of extragalactic interest.

  16. Keck Adaptive Optics Imaging of Nearby Young Stars: Detection of Close Multiple Systems

    CERN Document Server

    Brandeker, A; Najita, J R; Brandeker, Alexis; Jayawardhana, Ray; Najita, Joan

    2003-01-01

    Using adaptive optics on the Keck II 10-meter telescope on Mauna Kea, we have surveyed 24 of the nearest young stars known in search of close companions. Our sample includes members of the MBM 12 and TW Hydrae young associations and the classical T Tauri binary UY Aurigae in the Taurus star-forming region. We present relative photometry and accurate astrometry for 10 close multiple systems. The multiplicity frequency in the TW Hydrae and MBM 12 groups are high in comparison to other young regions, though the significance of this result is low because of the small number statistics. We resolve S 18 into a triple system including a tight 63 mas (projected separation of 17 AU at a distance of 275 pc) binary for the first time, with a hierarchical configuration reminiscent of VW Chamaeleontis and T Tauri. Another tight binary in our sample -- TWA 5Aab (54 mas or 3 AU at 55 pc) -- offers the prospect of dynamical mass measurement using astrometric observations within a few years, and thus could be important for te...

  17. Radio over fiber link with adaptive order n‐QAM optical phase modulated OFDM and digital coherent detection

    DEFF Research Database (Denmark)

    Arlunno, Valeria; Borkowski, Robert; Guerrero Gonzalez, Neil

    2011-01-01

    Successful digital coherent demodulation of asynchronous optical phase‐modulated adaptive order QAM (4, 16, and 64) orthogonal frequency division multiplexing signals is achieved by a single reconfigurable digital receiver after 78 km of optical deployed fiber transmission....

  18. Adaptive Optics for Industry and Medicine International Workshop.

    Science.gov (United States)

    1998-01-07

    aberration of the human eye," Biophysics 7, 766-795 (1962).I 5. F. Berny, S. Slansky, "Wavefront determination resulting from foucault test as applied to the...visualization phase distortions by the Foucault knife-edge method, by the autoreference interferometer and by the Zemike valve method [27]. The last was used for...is shorter [9]. ACKNOWLEGMENTS I thank Michael Loktev, who has wrote software for adaptive lens. This research is supported in part by European

  19. SHARDS: AN OPTICAL SPECTRO-PHOTOMETRIC SURVEY OF DISTANT GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Gonzalez, Pablo G.; Cava, Antonio; Barro, Guillermo; Villar, Victor; Cardiel, Nicolas; Espino, Nestor; Gallego, Jesus [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Ferreras, Ignacio [Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT (United Kingdom); Rodriguez-Espinosa, Jose Miguel; Balcells, Marc; Cepa, Jordi [Instituto de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain); Alonso-Herrero, Almudena [Instituto de Fisica de Cantabria, CSIC-Universidad de Cantabria, E-39005 Santander (Spain); Cenarro, Javier [Centro de Estudios de Fisica del Cosmos de Aragon, Plaza San Juan 1, Planta 2, E-44001 Teruel (Spain); Charlot, Stephane [Institut d' Astrophysique de Paris, CNRS, Universite Pierre and Marie Curie, UMR 7095, 98bis bd Arago, F-75014 Paris (France); Cimatti, Andrea [Dipartimento di Astronomia, Universita degli Studi di Bologna, I-40127 Bologna (Italy); Conselice, Christopher J. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Daddi, Emmanuele; Elbaz, David [CEA, Laboratoire AIM, Irfu/SAp, F-91191 Gif-sur-Yvette (France); Donley, Jennifer [Los Alamos National Laboratory, Los Alamos, NM (United States); Gobat, R. [Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d' Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette (France); and others

    2013-01-01

    We present the Survey for High-z Absorption Red and Dead Sources (SHARDS), an ESO/GTC Large Program carried out using the OSIRIS instrument on the 10.4 m Gran Telescopio Canarias (GTC). SHARDS is an ultra-deep optical spectro-photometric survey of the GOODS-N field covering 130 arcmin{sup 2} at wavelengths between 500 and 950 nm with 24 contiguous medium-band filters (providing a spectral resolution R {approx} 50). The data reach an AB magnitude of 26.5 (at least at a 3{sigma} level) with sub-arcsec seeing in all bands. SHARDS' main goal is to obtain accurate physical properties of intermediate- and high-z galaxies using well-sampled optical spectral energy distributions (SEDs) with sufficient spectral resolution to measure absorption and emission features, whose analysis will provide reliable stellar population and active galactic nucleus (AGN) parameters. Among the different populations of high-z galaxies, SHARDS' principal targets are massive quiescent galaxies at z > 1, whose existence is one of the major challenges facing current hierarchical models of galaxy formation. In this paper, we outline the observational strategy and include a detailed discussion of the special reduction and calibration procedures which should be applied to the GTC/OSIRIS data. An assessment of the SHARDS data quality is also performed. We present science demonstration results on the detection and study of emission-line galaxies (star-forming objects and AGNs) at z = 0-5. We also analyze the SEDs for a sample of 27 quiescent massive galaxies with spectroscopic redshifts in the range 1.0 < z {approx}< 1.4. We discuss the improvements introduced by the SHARDS data set in the analysis of their star formation history and stellar properties. We discuss the systematics arising from the use of different stellar population libraries, typical in this kind of study. Averaging the results from the different libraries, we find that the UV-to-MIR SEDs of the massive quiescent galaxies at

  20. An Optical Survey for Black Holes in the Kepler Field

    Science.gov (United States)

    Orosz, Jerome A.; Welsh, W. F.; Windmiller, G.; Short, D. R.

    2014-01-01

    Black holes and neutron stars represent the final evolutionary stages of the most massive stars, and as such are a fossil record of high-mass stellar evolution in the Milky Way. Black holes and neutron stars are ideal laboratories to test General Relativity in the strong field limit. The number of such objects in the Milky Way is not precisely known, but there are roughly one billion neutron stars in the galaxy based on the observed numbers of radio pulsars with corrections for the many observational biases, and about 100 million black holes based on the behavior of the Initial Mass Function at high stellar masses. All of the known steller-mass black holes (and a fair number of neutron stars) are in "X-ray binaries" that were discovered because of their luminous X-ray emission. The requirement to be in an X-ray binary that has recently exhibited X-ray activity places strong observational biases on the discovery rate of stellar-mass black holes. Thus the 21 X-ray binaries that have confirmed black holes represent the tip of the iceberg. We have therefore began an optical survey using Kepler data that may uncover several black holes and neutron stars in both "quiescent'" X-ray binaries and "pre-contact" X-ray binaries. Any such discoveries will be of interest in their own right. In addition, the rate of such objects uncovered in our survey (or even the lack of discoveries) will place meaningful constraints on the formation theories of low-mass X-ray binaries and thus compact objects. We present here a progress report of our work so far, including techniques we use for light curve classification and the identification of the variability type. We gratefully acknowledge support from NASA via the grant NNX13AF23G.

  1. Analysis of adaptive laser scanning optical system with focus-tunable components

    Science.gov (United States)

    Pokorný, P.; Mikš, A.; Novák, J.; Novák, P.

    2015-05-01

    This work presents a primary analysis of an adaptive laser scanner based on two-mirror beam-steering device and focustunable components (lenses with tunable focal length). It is proposed an optical scheme of an adaptive laser scanner, which can focus the laser beam in a continuous way to a required spatial position using the lens with tunable focal length. This work focuses on a detailed analysis of the active optical or opto-mechanical components (e.g. focus-tunable lenses) mounted in the optical systems of laser scanners. The algebraic formulas are derived for ray tracing through different configurations of the scanning optical system and one can calculate angles of scanner mirrors and required focal length of the tunable-focus component provided that the position of the focused beam in 3D space is given with a required tolerance. Computer simulations of the proposed system are performed using MATLAB.

  2. Axial range of conjugate adaptive optics in two-photon microscopy

    CERN Document Server

    Paudel, Hari P; Mertz, Jerome; Bifano, Thomas

    2015-01-01

    We describe an adaptive optics technique for two-photon microscopy in which the deformable mirror used for aberration compensation is positioned in a plane conjugate to the plane of the aberration. We demonstrate in a proof-of-principle experiment that this technique yields a large field of view advantage in comparison to standard pupil-conjugate adaptive optics. Further, we show that the extended field of view in conjugate AO is maintained over a relatively large axial translation of the deformable mirror with respect to the conjugate plane. We conclude with a discussion of limitations and prospects for the conjugate AO technique in two-photon biological microscopy.

  3. AVES-IMCO: an adaptive optics visible spectrograph and imager/coronograph for NAOS

    Science.gov (United States)

    Beuzit, Jean-Luc; Lagrange, A.-M.; Mouillet, D.; Chauvin, G.; Stadler, E.; Charton, J.; Lacombe, F.; AVES-IMCO Team

    2001-05-01

    The NAOS adaptive optics system will very soon provide diffraction-limited images on the VLT, down to the visible wavelengths (0.020 arcseconds at 0.83 micron for instance). At the moment, the only instrument dedicated to NAOS is the CONICA spectro-imager, operating in the near-infrared from 1 to 5 microns. We are now proposing to ESO, in collaboration with an Italian group, the development of a visible spectrograph/imager/coronograph, AVES-IMCO (Adaptive Optics Visual Echelle Spectrograph and IMager/COronograph). We present here the general concept of the new instrument as well as its expected performances in the different modes.

  4. Investigation of Power8 processors for astronomical adaptive optics real-time control

    CERN Document Server

    Basden, Alastair

    2015-01-01

    The forthcoming Extremely Large Telescopes all require adaptive optics systems for their successful operation. The real-time control for these systems becomes computationally challenging, in part limited by the memory bandwidths required for wavefront reconstruction. We investigate new POWER8 processor technologies applied to the problem of real-time control for adaptive optics. These processors have a large memory bandwidth, and we show that they are suitable for operation of first-light ELT instrumentation, and propose some potential real-time control system designs. A CPU-based real-time control system significantly reduces complexity, improves maintainability, and leads to increased longevity for the real-time control system.

  5. Robo-AO: The First Autonomous Laser Guide Star Adaptive Optics System for Small Telescopes

    Science.gov (United States)

    Riddle, Reed L.; Baranec, C.; Ramaprakash, A. N.; Law, N.; Tendulkar, S.; Kulkarni, S.; Bui, K.; Burse, M.; Chordia, P.; Das, H.; Dekany, R.; Kasliwal, M.; Ofek, E.; Zolkower, J.

    2011-01-01

    Robo-AO will be the first fully autonomous laser guide star adaptive optics and science system. Specifically designed to take advantage of small (1 to 3 meter) telescopes, Robo-AO will deliver high angular resolution science in the visible and near infrared for up to hundreds of targets per night. This will enable the exploration of science programs not practical for larger aperture adaptive optics systems. This presentation discusses the current status of the Robo-AO project, including the laboratory testbed, laser guide star facility and plans for a demonstration of the fully autonomous system next year.

  6. Fixation light hue bias revisited: implications for using adaptive optics to study color vision.

    Science.gov (United States)

    Hofer, H J; Blaschke, J; Patolia, J; Koenig, D E

    2012-03-01

    Current vision science adaptive optics systems use near infrared wavefront sensor 'beacons' that appear as red spots in the visual field. Colored fixation targets are known to influence the perceived color of macroscopic visual stimuli (Jameson, D., & Hurvich, L. M. (1967). Fixation-light bias: An unwanted by-product of fixation control. Vision Research, 7, 805-809.), suggesting that the wavefront sensor beacon may also influence perceived color for stimuli displayed with adaptive optics. Despite its importance for proper interpretation of adaptive optics experiments on the fine scale interaction of the retinal mosaic and spatial and color vision, this potential bias has not yet been quantified or addressed. Here we measure the impact of the wavefront sensor beacon on color appearance for dim, monochromatic point sources in five subjects. The presence of the beacon altered color reports both when used as a fixation target as well as when displaced in the visual field with a chromatically neutral fixation target. This influence must be taken into account when interpreting previous experiments and new methods of adaptive correction should be used in future experiments using adaptive optics to study color.

  7. Adaptive optics for reduced threshold energy in femtosecond laser induced optical breakdown in water based eye model

    Science.gov (United States)

    Hansen, Anja; Krueger, Alexander; Ripken, Tammo

    2013-03-01

    In ophthalmic microsurgery tissue dissection is achieved using femtosecond laser pulses to create an optical breakdown. For vitreo-retinal applications the irradiance distribution in the focal volume is distorted by the anterior components of the eye causing a raised threshold energy for breakdown. In this work, an adaptive optics system enables spatial beam shaping for compensation of aberrations and investigation of wave front influence on optical breakdown. An eye model was designed to allow for aberration correction as well as detection of optical breakdown. The eye model consists of an achromatic lens for modeling the eye's refractive power, a water chamber for modeling the tissue properties, and a PTFE sample for modeling the retina's scattering properties. Aberration correction was performed using a deformable mirror in combination with a Hartmann-Shack-sensor. The influence of an adaptive optics aberration correction on the pulse energy required for photodisruption was investigated using transmission measurements for determination of the breakdown threshold and video imaging of the focal region for study of the gas bubble dynamics. The threshold energy is considerably reduced when correcting for the aberrations of the system and the model eye. Also, a raise in irradiance at constant pulse energy was shown for the aberration corrected case. The reduced pulse energy lowers the potential risk of collateral damage which is especially important for retinal safety. This offers new possibilities for vitreo-retinal surgery using femtosecond laser pulses.

  8. DeepSurveyCam—A Deep Ocean Optical Mapping System

    Directory of Open Access Journals (Sweden)

    Tom Kwasnitschka

    2016-01-01

    Full Text Available Underwater photogrammetry and in particular systematic visual surveys of the deep sea are by far less developed than similar techniques on land or in space. The main challenges are the rough conditions with extremely high pressure, the accessibility of target areas (container and ship deployment of robust sensors, then diving for hours to the ocean floor, and the limitations of localization technologies (no GPS. The absence of natural light complicates energy budget considerations for deep diving flash-equipped drones. Refraction effects influence geometric image formation considerations with respect to field of view and focus, while attenuation and scattering degrade the radiometric image quality and limit the effective visibility. As an improvement on the stated issues, we present an AUV-based optical system intended for autonomous visual mapping of large areas of the seafloor (square kilometers in up to 6000 m water depth. We compare it to existing systems and discuss tradeoffs such as resolution vs. mapped area and show results from a recent deployment with 90,000 mapped square meters of deep ocean floor.

  9. DeepSurveyCam--A Deep Ocean Optical Mapping System.

    Science.gov (United States)

    Kwasnitschka, Tom; Köser, Kevin; Sticklus, Jan; Rothenbeck, Marcel; Weiß, Tim; Wenzlaff, Emanuel; Schoening, Timm; Triebe, Lars; Steinführer, Anja; Devey, Colin; Greinert, Jens

    2016-01-28

    Underwater photogrammetry and in particular systematic visual surveys of the deep sea are by far less developed than similar techniques on land or in space. The main challenges are the rough conditions with extremely high pressure, the accessibility of target areas (container and ship deployment of robust sensors, then diving for hours to the ocean floor), and the limitations of localization technologies (no GPS). The absence of natural light complicates energy budget considerations for deep diving flash-equipped drones. Refraction effects influence geometric image formation considerations with respect to field of view and focus, while attenuation and scattering degrade the radiometric image quality and limit the effective visibility. As an improvement on the stated issues, we present an AUV-based optical system intended for autonomous visual mapping of large areas of the seafloor (square kilometers) in up to 6000 m water depth. We compare it to existing systems and discuss tradeoffs such as resolution vs. mapped area and show results from a recent deployment with 90,000 mapped square meters of deep ocean floor.

  10. DeepSurveyCam—A Deep Ocean Optical Mapping System

    Science.gov (United States)

    Kwasnitschka, Tom; Köser, Kevin; Sticklus, Jan; Rothenbeck, Marcel; Weiß, Tim; Wenzlaff, Emanuel; Schoening, Timm; Triebe, Lars; Steinführer, Anja; Devey, Colin; Greinert, Jens

    2016-01-01

    Underwater photogrammetry and in particular systematic visual surveys of the deep sea are by far less developed than similar techniques on land or in space. The main challenges are the rough conditions with extremely high pressure, the accessibility of target areas (container and ship deployment of robust sensors, then diving for hours to the ocean floor), and the limitations of localization technologies (no GPS). The absence of natural light complicates energy budget considerations for deep diving flash-equipped drones. Refraction effects influence geometric image formation considerations with respect to field of view and focus, while attenuation and scattering degrade the radiometric image quality and limit the effective visibility. As an improvement on the stated issues, we present an AUV-based optical system intended for autonomous visual mapping of large areas of the seafloor (square kilometers) in up to 6000 m water depth. We compare it to existing systems and discuss tradeoffs such as resolution vs. mapped area and show results from a recent deployment with 90,000 mapped square meters of deep ocean floor. PMID:26828495

  11. Towards feasible and effective predictive wavefront control for adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Poyneer, L A; Veran, J

    2008-06-04

    We have recently proposed Predictive Fourier Control, a computationally efficient and adaptive algorithm for predictive wavefront control that assumes frozen flow turbulence. We summarize refinements to the state-space model that allow operation with arbitrary computational delays and reduce the computational cost of solving for new control. We present initial atmospheric characterization using observations with Gemini North's Altair AO system. These observations, taken over 1 year, indicate that frozen flow is exists, contains substantial power, and is strongly detected 94% of the time.

  12. Towards feasible and effective predictive wavefront control for adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Poyneer, L A; Veran, J

    2008-06-04

    We have recently proposed Predictive Fourier Control, a computationally efficient and adaptive algorithm for predictive wavefront control that assumes frozen flow turbulence. We summarize refinements to the state-space model that allow operation with arbitrary computational delays and reduce the computational cost of solving for new control. We present initial atmospheric characterization using observations with Gemini North's Altair AO system. These observations, taken over 1 year, indicate that frozen flow is exists, contains substantial power, and is strongly detected 94% of the time.

  13. Adaptation of Instructional Materials Motivation Survey to Turkish: A Validity and Reliability Study

    Directory of Open Access Journals (Sweden)

    Hülya Kutu

    2011-06-01

    Full Text Available The purpose of this study was to adapt “Instructional Materials Motivation Survey [IMMS]”, developed by J. M. Keller, to Turkish and investigate validity and reliability of the Turkish version of the survey. The original version of the survey was composed of 36 items gathered under four factors (attention, relevance, confidence, satisfaction. The survey was translated into Turkish. Views of 15 faculty members who were expert in Turkish and foreign language were sought in terms of correctness of meaning in Turkish and integrity of items into culture of Turkish education system. Turkish version of the survey was administered to total of 262 university students from Education Faculties of Ataturk and Erzincan Universities. The item-total correlations were calculated, and items which had negative or low correlation with the total survey score (r<.30 were excluded from the survey. The construct validity of the survey was examined by exploratory factor analysis. Varimax rotation technique was used due to the separation into irrelevant factors. Finally the survey was constructed from 24 item gathered under two factors. The reliability coefficient (Cronbach Alpha for the whole survey was calculated as 0.83, and 0.79 and 0.69 for the two sub-factors respectively.

  14. Survey of subsurface geophysical exploration technologies adaptable to an airborne platform

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, K.A.

    1992-12-01

    This report has been prepared by the US Department of Energy (DOE) as part of a Research Development Demonstration Testing and Evaluation (RDDT E) project by EG G Energy Measurement's (EG G/EM) Remote Sensing Laboratory. It examines geophysical detection techniques which may be used in Environmental Restoration/Waste Management (ER/WM) surveys to locate buried waste, waste containers, potential waste migratory paths, and aquifer depths. Because of the Remote Sensing Laboratory's unique survey capabilities, only those technologies which have been adapted or are capable of being adapted to an airborne platform were studied. This survey describes several of the available subsurface survey technologies and discusses the basic capabilities of each: the target detectability, required geologic conditions, and associated survey methods. Because the airborne capabilities of these survey techniques have not been fully developed, the chapters deal mostly with the ground-based capabilities of each of the technologies, with reference made to the airborne capabilities where applicable. The information about each survey technique came from various contractors whose companies employ these specific technologies. EG G/EM cannot guarantee or verify the accuracy of the contractor information; however, the data given is an indication of the technologies that are available.

  15. Survey of subsurface geophysical exploration technologies adaptable to an airborne platform

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, K.A.

    1992-12-01

    This report has been prepared by the US Department of Energy (DOE) as part of a Research Development Demonstration Testing and Evaluation (RDDT&E) project by EG&G Energy Measurement`s (EG&G/EM) Remote Sensing Laboratory. It examines geophysical detection techniques which may be used in Environmental Restoration/Waste Management (ER/WM) surveys to locate buried waste, waste containers, potential waste migratory paths, and aquifer depths. Because of the Remote Sensing Laboratory`s unique survey capabilities, only those technologies which have been adapted or are capable of being adapted to an airborne platform were studied. This survey describes several of the available subsurface survey technologies and discusses the basic capabilities of each: the target detectability, required geologic conditions, and associated survey methods. Because the airborne capabilities of these survey techniques have not been fully developed, the chapters deal mostly with the ground-based capabilities of each of the technologies, with reference made to the airborne capabilities where applicable. The information about each survey technique came from various contractors whose companies employ these specific technologies. EG&G/EM cannot guarantee or verify the accuracy of the contractor information; however, the data given is an indication of the technologies that are available.

  16. Dynamic optical aberration correction with adaptive coded apertures techniques in conformal imaging

    Science.gov (United States)

    Li, Yan; Hu, Bin; Zhang, Pengbin; Zhang, Binglong

    2015-02-01

    Conformal imaging systems are confronted with dynamic aberration in optical design processing. In classical optical designs, for combination high requirements of field of view, optical speed, environmental adaption and imaging quality, further enhancements can be achieved only by the introduction of increased complexity of aberration corrector. In recent years of computational imaging, the adaptive coded apertures techniques which has several potential advantages over more traditional optical systems is particularly suitable for military infrared imaging systems. The merits of this new concept include low mass, volume and moments of inertia, potentially lower costs, graceful failure modes, steerable fields of regard with no macroscopic moving parts. Example application for conformal imaging system design where the elements of a set of binary coded aperture masks are applied are optimization designed is presented in this paper, simulation results show that the optical performance is closely related to the mask design and the reconstruction algorithm optimization. As a dynamic aberration corrector, a binary-amplitude mask located at the aperture stop is optimized to mitigate dynamic optical aberrations when the field of regard changes and allow sufficient information to be recorded by the detector for the recovery of a sharp image using digital image restoration in conformal optical system.

  17. SOAR Adaptive Optics Observations of the Globular Cluster NGC6496

    CERN Document Server

    Fraga, Luciano; Tokovinin, Andrei

    2013-01-01

    We present high-quality BVRI photometric data in the field of globular cluster NGC 6496 obtained with the SOAR Telescope Adaptive Module (SAM). Our observations were collected as part of the ongoing SAM commissioning. The distance modulus and cluster color excess as found from the red clump is $\\mMv = 15.71 \\pm 0.02$\\,mag and $\\EVI = 0.28 \\pm 0.02$\\,mag. An age of $10.5 \\pm 0.5$\\,Gyr is determined from the difference in magnitude between the red clump and the subgiant branch. These parameters are in excellent agreement with the values derived from isochrone fitting. From the color-magnitude diagram we find a metallicity of $\\feh = -0.65$\\,dex and hence support a disk classification for NGC 6496. The complete $BVRI$ data set for NGC 6469 is made available in the electronic edition of the Journal.

  18. Soar adaptive optics observations of the globular cluster NGC 6496

    Energy Technology Data Exchange (ETDEWEB)

    Fraga, Luciano [Southern Observatory for Astrophysical Research, Casilla 603, La Serena (Chile); Kunder, Andrea; Tokovinin, Andrei, E-mail: lfraga@ctio.noao.edu, E-mail: lfraga@lna.br [Cerro Tololo Inter-American Observatory, Casilla 603, La Serena (Chile)

    2013-06-01

    We present high-quality BVRI photometric data in the field of globular cluster NGC 6496 obtained with the SOAR Telescope Adaptive Module (SAM). Our observations were collected as part of the ongoing SAM commissioning. The distance modulus and cluster color excess as found from the red clump are (m – M) {sub V} = 15.71 ± 0.02 mag and E(V – I) = 0.28 ± 0.02 mag. An age of 10.5 ± 0.5 Gyr is determined from the difference in magnitude between the red clump and the subgiant branch. These parameters are in excellent agreement with the values derived from isochrone fitting. From the color-magnitude diagram we find a metallicity of [Fe/H] = –0.65 dex and hence support a disk classification for NGC 6496. The complete BVRI data set for NGC 6469 is made available in the electronic edition of the Journal.

  19. Laser based bi-directional Gbit ground links with the Tesat transportable adaptive optical ground station

    Science.gov (United States)

    Heine, Frank; Saucke, Karen; Troendle, Daniel; Motzigemba, Matthias; Bischl, Hermann; Elser, Dominique; Marquardt, Christoph; Henninger, Hennes; Meyer, Rolf; Richter, Ines; Sodnik, Zoran

    2017-02-01

    Optical ground stations can be an alternative to radio frequency based transmit (forward) and receive (return) systems for data relay services and other applications including direct to earth optical communications from low earth orbit spacecrafts, deep space receivers, space based quantum key distribution systems and Tbps capacity feeder links to geostationary spacecrafts. The Tesat Transportable Adaptive Optical Ground Station is operational since September 2015 at the European Space Agency site in Tenerife, Spain.. This paper reports about the results of the 2016 experimental campaigns including the characterization of the optical channel from Tenerife for an optimized coding scheme, the performance of the T-AOGS under different atmospheric conditions and the first successful measurements of the suitability of the Alphasat LCT optical downlink performance for future continuous variable quantum key distribution systems.

  20. High-accuracy calibration of an adaptive optics system using a phase shifting diffraction interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Bauman, B J; Campbell, E W; Olivier, S S; Sweider, D R

    1999-06-23

    A phase-shifting diffraction interferometer (PSDI) has been integrated into an adaptive optics (AO) system developed by LLNL for use on the three meter Shane telescope at Lick Observatory. The interferometer is an all fiber optic design, which is extremely compact. It is useful for calibrating the control sensors, measuring the aberrations of the entire AO optical train, and measuring the influence functions of the individual actuators on the deformable mirror. The PSDI is particularly well suited for this application because it measures converging, quasi-spherical wavefronts, such as are produced by an AO imaging system. Thus, a PSDI can be used to measure the aberrations of the entire AO system, in-situ and without errors introduced by auxiliary optics. This provides an extremely accurate measurement ({approximately} 5 nm RMS) of the optical properties of the AO system.

  1. Comparative study of infrared wavefront sensing solutions for adaptive optics

    Science.gov (United States)

    Plantet, C.; Fusco, T.; Guerineau, N.; Derelle, S.; Robert, C.

    2016-07-01

    The development of new low-noise infrared detectors, such as RAPID (CEA LETI/Sofradir) or SAPHIRA (Selex), has given the possibility to consider infrared wavefront sensing at low ux. We propose here a comparative study of near infrared (J and H bands) wavefront sensing concepts for mid and high orders estimation on a 8m- class telescope, relying on three existing wavefront sensors: the Shack-Hartmann sensor, the pyramid sensor and the quadri-wave lateral shearing interferometer. We consider several conceptual designs using the RAPID camera, making a trade-off between background flux, optical thickness and compatibility with a compact cryostat integration. We then study their sensitivity to noise in order to compare them in different practical scenarios. The pyramid provides the best performance, with a gain up to 0.5 magnitude, and has an advantageous setup.

  2. Push-pull membrane mirrors for adaptive optics.

    Science.gov (United States)

    Bonora, Stefano; Poletto, Luca

    2006-12-11

    We propose an improvement to the electrostatic membrane deformable mirror technique introducing push-pull capability that increases the performance in the correction of optical aberrations. The push-pull effect is achieved by the addition of some transparent electrodes on the top of the device. The transparent electrode is an indium-tin-oxide coated glass. The improvement of the mirror in generating surfaces is demonstrated by the comparison with a pull membrane mirror. The control is carried out in open loop by the knowledge of the response of each single electrode. An effective iterative strategy for the clipping management is presented. The performances are evaluated both in terms of Zernike polynomials generation and in terms of aberrations compensation based on the statistics of human eyes.

  3. Push-pull membrane mirrors for adaptive optics

    Science.gov (United States)

    Bonora, Stefano; Poletto, Luca

    2006-12-01

    We propose an improvement to the electrostatic membrane deformable mirror technique introducing push-pull capability that increases the performance in the correction of optical aberrations. The push-pull effect is achieved by the addition of some transparent electrodes on the top of the device. The transparent electrode is an indium-tin-oxide coated glass. The improvement of the mirror in generating surfaces is demonstrated by the comparison with a pull membrane mirror. The control is carried out in open loop by the knowledge of the response of each single electrode. An effective iterative strategy for the clipping management is presented. The performances are evaluated both in terms of Zernike polynomials generation and in terms of aberrations compensation based on the statistics of human eyes.

  4. A pilot study on slit lamp-adapted optical coherence tomography imaging of trabeculectomy filtering blebs.

    NARCIS (Netherlands)

    Theelen, T.; Wesseling, P.; Keunen, J.E.E.; Klevering, B.J.

    2007-01-01

    BACKGROUND: Our study aims to identify anatomical characteristics of glaucoma filtering blebs by means of slit lamp-adapted optical coherence tomography (SL-OCT) and to identify new parameters for the functional prognosis of the filter in the early post-operative period. METHODS: Patients with

  5. Placing Limits on Extragalactic Substructure with Gravitational Lenses and Adaptive Optics

    NARCIS (Netherlands)

    Lagattuta, David J.; Vegetti, S.; Auger, M. W.; Fassnacht, C. D.; Koopmans, L. V. E.; McKean, J. P.

    2011-01-01

    We present the first results from a systematic search for extragalactic substructure, using high resolution Adaptive Optics (AO) images of known strong gravitational lenses. In particular we focus on two lens systems, B0128+437 and B1939+666, placing limits on both luminous and dark matter substruct

  6. Extracting hysteresis from nonlinear measurement of wavefront-sensorless adaptive optics system

    NARCIS (Netherlands)

    Song, H.; Vdovin, G.; Fraanje, R.; Schitter, G.; Verhaegen, M.

    2008-01-01

    In many scientific and medical applications wavefront-sensorless adaptive optics (AO) systems are used to correct the wavefront aberration by optimizing a certain target parameter, which is nonlinear with respect to the control signal to the deformable mirror (DM). Hysteresis is the most common nonl

  7. A data-driven H2-optimal control approach for adaptive optics

    NARCIS (Netherlands)

    Hinnen, K.; Verhaegen, M.; Doelman, N.J.

    2008-01-01

    Adaptive optics (AO) is used in ground-based astronomical telescopes to improve the resolution by counteracting the effects of atmospheric turbulence. Most AO systems are based on a simple control law that neglects the temporal evolution of the distortions introduced by the atmosphere. This paper pr

  8. Observer-Based Control Techniques for the LBT Adaptive Optics under Telescope Vibrations

    NARCIS (Netherlands)

    Agapito, Guido; Quirós-Pacheco, Fernando; Tesi, Pietro; Riccardi, Armando; Esposito, Simone

    2011-01-01

    This paper addresses the application of observer-based control techniques for the adaptive optics system of the LBT telescope. In such a context, attention is focused on the use of Kalman and H∞ filters to estimate the temporal evolution of phase perturbations due to the atmospheric turbulence and

  9. Optimal control of tip-tilt modes on-sky adaptive optics demonstration

    NARCIS (Netherlands)

    Doelman, N.J.; Fraanje, P.R.; Breeje, R. den

    2011-01-01

    An H2-optimal control approach for Adaptive Optics has been validated in an on-sky experiment on a solar telescope. A substantial performance improvement over the integrator control approach is demonstrated for control of the tip-tilt modes. The experimental results correspond reasonably well with

  10. Adaptive PMD Compensation in 10 Gbit/s RZ Optical Communication System

    Institute of Scientific and Technical Information of China (English)

    Yu; Li; Zhang; Xiaoguang; Zhou; Guangtao; Shen; Yu; Zheng; Yuan; Li; Chaoyang; Liu; Yumin; Chen; Lin; Yang; Bojun

    2003-01-01

    We report an experiment of adaptive compensation for polarization mode dispersion (PMD) in 10Gbit/s return zero (RZ) optical communication system. The quasi-real-time PMD compensation is realized. The algorithm so-called particle swarm optimization (PSO) is used to control feedback compensation system.

  11. Development of a scalable generic platform for adaptive optics real time control

    Science.gov (United States)

    Surendran, Avinash; Burse, Mahesh P.; Ramaprakash, A. N.; Parihar, Padmakar

    2015-06-01

    The main objective of the present project is to explore the viability of an adaptive optics control system based exclusively on Field Programmable Gate Arrays (FPGAs), making strong use of their parallel processing capability. In an Adaptive Optics (AO) system, the generation of the Deformable Mirror (DM) control voltages from the Wavefront Sensor (WFS) measurements is usually through the multiplication of the wavefront slopes with a predetermined reconstructor matrix. The ability to access several hundred hard multipliers and memories concurrently in an FPGA allows performance far beyond that of a modern CPU or GPU for tasks with a well-defined structure such as Adaptive Optics control. The target of the current project is to generate a signal for a real time wavefront correction, from the signals coming from a Wavefront Sensor, wherein the system would be flexible to accommodate all the current Wavefront Sensing techniques and also the different methods which are used for wavefront compensation. The system should also accommodate for different data transmission protocols (like Ethernet, USB, IEEE 1394 etc.) for transmitting data to and from the FPGA device, thus providing a more flexible platform for Adaptive Optics control. Preliminary simulation results for the formulation of the platform, and a design of a fully scalable slope computer is presented.

  12. Conventional to Cloud: Detailed survey and comparative study of multimedia streaming rate Adaptation

    Directory of Open Access Journals (Sweden)

    Selvaraj Kesavan

    2014-06-01

    Full Text Available Infotainment and telecommunication industry is fast evolving towards personalized network connectivity and newer applications services ranging from music playback to ever changing telephony applications. Streaming is the key services which enables the users to view real time multimedia content on-the-go anywhere and everywhere. In streaming, quality of service is a major concern in the increasing network traffic and high user demand. Rate adaptation is crucial process to dynamically evaluate, select and control the media rate based on the network deviation, processing capability and to ensure the best class of service, user experience to the consumer. In this paper, we focuses on the comprehensive survey of existing rate adaptation algorithms used in conventional, adaptive, cloud assisted streaming methods and lists the merits ,limitations of the algorithms. With an experiment setup, we also evaluate and analyze the rate adaptation behavior of the streaming techniques using streaming client.

  13. Adaptive optics in spinning disk microscopy: improved contrast and brightness by a simple and fast method.

    Science.gov (United States)

    Fraisier, V; Clouvel, G; Jasaitis, A; Dimitrov, A; Piolot, T; Salamero, J

    2015-09-01

    Multiconfocal microscopy gives a good compromise between fast imaging and reasonable resolution. However, the low intensity of live fluorescent emitters is a major limitation to this technique. Aberrations induced by the optical setup, especially the mismatch of the refractive index and the biological sample itself, distort the point spread function and further reduce the amount of detected photons. Altogether, this leads to impaired image quality, preventing accurate analysis of molecular processes in biological samples and imaging deep in the sample. The amount of detected fluorescence can be improved with adaptive optics. Here, we used a compact adaptive optics module (adaptive optics box for sectioning optical microscopy), which was specifically designed for spinning disk confocal microscopy. The module overcomes undesired anomalies by correcting for most of the aberrations in confocal imaging. Existing aberration detection methods require prior illumination, which bleaches the sample. To avoid multiple exposures of the sample, we established an experimental model describing the depth dependence of major aberrations. This model allows us to correct for those aberrations when performing a z-stack, gradually increasing the amplitude of the correction with depth. It does not require illumination of the sample for aberration detection, thus minimizing photobleaching and phototoxicity. With this model, we improved both signal-to-background ratio and image contrast. Here, we present comparative studies on a variety of biological samples.

  14. Characterization of a tunable astigmatic fluidic lens with adaptive optics correction for compact phoropter application

    Science.gov (United States)

    Fuh, Yiin-Kuen; Huang, Chieh-Tse

    2014-07-01

    Fluidically controlled lenses which adaptively correct prescribed refractive error without mechanically moving parts are extensively applied in the ophthalmic applications. Capable of variable-focusing properties, however, the associated aberrations due to curvature change and refractive index mismatch can inherently degrade image quality severely. Here we present the experimental study of the aberrations in tunable astigmatic lens and use of adaptive optics to compensate for the wavefront errors. Characterization of the optical properties of the individual lenses is carried out by Shack-Hartmann measurements. An adaptive optics (AO) based scheme is demonstrated for three injected fluidic volumes, resulting in a substantial reduction of the wavefront errors from -0.12, -0.25, -0.32 to 0.01, -0.01, -0.20 μm, respectively, corresponding to the optical power tenability of 0.83 to 1.84 D. Furthermore, an integrated optical phoroptor consisting of adjustable astigmatic lenses and AO correction is demonstrated such that an induced refraction error of -1 D cylinder at 180° of a model eye vision is experimentally corrected.

  15. The adaptive optics and transmit system for NASA's Laser Communications Relay Demonstration project

    Science.gov (United States)

    Roberts, Lewis C.; Burruss, Rick; Fregoso, Santos; Herzog, Harrison; Piazzola, Sabino; Roberts, Jennifer E.; Spiers, Gary D.; Truong, Tuan N.

    2016-09-01

    The Laser Communication Relay Demonstration is NASA's multi-year demonstration of laser communication to a geosynchronous satellite. We are currently assembling the optical system for the first of the two baseline ground stations. The optical system consists of an adaptive optics system, the transmit system and a camera for target acquisition. The adaptive optics system is responsible for compensating the downlink beam for atmospheric turbulence and coupling it into the modem's single mode fiber. The adaptive optics system is a woofer/tweeter design, with one deformable mirror correcting for low spatial frequencies with large amplitude and a second deformable mirror correcting for high spatial frequencies with small amplitude. The system uses a Shack- Hartmann wavefront sensor. The transmit system relays four beacon beams and one communication laser to the telescope for propagation to the space terminal. Both the uplink and downlink beams are centered at 1.55 microns. We present an overview of the design of the system as well as performance predictions including time series of coupling efficiency and expected uplink beam quality.

  16. Adaptive optics imaging of the outer retinal tubules in Bietti's crystalline dystrophy.

    Science.gov (United States)

    Battu, R; Akkali, M C; Bhanushali, D; Srinivasan, P; Shetty, R; Berendschot, T T J M; Schouten, J S A G; Webers, C A

    2016-05-01

    PurposeTo study the outer retinal tubules using spectral domain optical coherence tomography and adaptive optics and in patients with Bietti's crystalline dystrophy.MethodsTen eyes of five subjects from five independent families with Bietti's crystalline Dystrophy (BCD) were characterized with best-corrected visual acuity (BCVA), full-field electroretinography, and fundus autofluorescence (FAF). High-resolution images were obtained with the spectral domain optical coherence tomography (SD-OCT) and adaptive optics (AO).ResultsSD-OCT showed prominent outer retinal layer loss and outer retinal tubulations at the margin of outer retinal loss. AO images displayed prominent macrotubules and microtubules with characteristic features in eight out of the 10 eyes. Crystals were present in all ten eyes. There was a reduction in the cone count in all eyes in the area outside the outer retinal tubules (ORT).ConclusionsThis study describes the morphology of the outer retinal tubules when imaged enface on the adaptive optics in patients with BCD. These findings provide insight into the macular structure of these patients. This may have prognostic implications and refine the study on the pathogenesis of BCD.

  17. A novel data adaptive detection scheme for distributed fiber optic acoustic sensing

    Science.gov (United States)

    Ölçer, Íbrahim; Öncü, Ahmet

    2016-05-01

    We introduce a new approach for distributed fiber optic sensing based on adaptive processing of phase sensitive optical time domain reflectometry (Φ-OTDR) signals. Instead of conventional methods which utilizes frame averaging of detected signal traces, our adaptive algorithm senses a set of noise parameters to enhance the signal-to-noise ratio (SNR) for improved detection performance. This data set is called the secondary data set from which a weight vector for the detection of a signal is computed. The signal presence is sought in the primary data set. This adaptive technique can be used for vibration detection of health monitoring of various civil structures as well as any other dynamic monitoring requirements such as pipeline and perimeter security applications.

  18. Adaptive optics via pupil segmentation for high-resolution imaging in biological tissues.

    Science.gov (United States)

    Ji, Na; Milkie, Daniel E; Betzig, Eric

    2010-02-01

    Biological specimens are rife with optical inhomogeneities that seriously degrade imaging performance under all but the most ideal conditions. Measuring and then correcting for these inhomogeneities is the province of adaptive optics. Here we introduce an approach to adaptive optics in microscopy wherein the rear pupil of an objective lens is segmented into subregions, and light is directed individually to each subregion to measure, by image shift, the deflection faced by each group of rays as they emerge from the objective and travel through the specimen toward the focus. Applying our method to two-photon microscopy, we could recover near-diffraction-limited performance from a variety of biological and nonbiological samples exhibiting aberrations large or small and smoothly varying or abruptly changing. In particular, results from fixed mouse cortical slices illustrate our ability to improve signal and resolution to depths of 400 microm.

  19. Sensorless adaptive optics system based on image second moment measurements

    Science.gov (United States)

    Agbana, Temitope E.; Yang, Huizhen; Soloviev, Oleg; Vdovin, Gleb; Verhaegen, Michel

    2016-04-01

    This paper presents experimental results of a static aberration control algorithm based on the linear relation be- tween mean square of the aberration gradient and the second moment of point spread function for the generation of control signal input for a deformable mirror (DM). Results presented in the work of Yang et al.1 suggested a good feasibility of the method for correction of static aberration for point and extended sources. However, a practical realisation of the algorithm has not been demonstrated. The goal of this article is to check the method experimentally in the real conditions of the present noise, finite dynamic range of the imaging camera, and system misalignments. The experiments have shown strong dependence of the linearity of the relationship on image noise and overall image intensity, which depends on the aberration level. Also, the restoration capability and the rate of convergence of the AO system for aberrations generated by the deformable mirror are experi- mentally investigated. The presented approach as well as the experimental results finds practical application in compensation of static aberration in adaptive microscopic imaging system.

  20. FOCAL PLANE WAVEFRONT SENSING USING RESIDUAL ADAPTIVE OPTICS SPECKLES

    Energy Technology Data Exchange (ETDEWEB)

    Codona, Johanan L.; Kenworthy, Matthew, E-mail: jlcodona@gmail.com [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

    2013-04-20

    Optical imperfections, misalignments, aberrations, and even dust can significantly limit sensitivity in high-contrast imaging systems such as coronagraphs. An upstream deformable mirror (DM) in the pupil can be used to correct or compensate for these flaws, either to enhance the Strehl ratio or suppress the residual coronagraphic halo. Measurement of the phase and amplitude of the starlight halo at the science camera is essential for determining the DM shape that compensates for any non-common-path (NCP) wavefront errors. Using DM displacement ripples to create a series of probe and anti-halo speckles in the focal plane has been proposed for space-based coronagraphs and successfully demonstrated in the lab. We present the theory and first on-sky demonstration of a technique to measure the complex halo using the rapidly changing residual atmospheric speckles at the 6.5 m MMT telescope using the Clio mid-IR camera. The AO system's wavefront sensor measurements are used to estimate the residual wavefront, allowing us to approximately compute the rapidly evolving phase and amplitude of speckle halo. When combined with relatively short, synchronized science camera images, the complex speckle estimates can be used to interferometrically analyze the images, leading to an estimate of the static diffraction halo with NCP effects included. In an operational system, this information could be collected continuously and used to iteratively correct quasi-static NCP errors or suppress imperfect coronagraphic halos.

  1. Focal Plane Wavefront Sensing using Residual Adaptive Optics Speckles

    CERN Document Server

    Codona, Johanan L

    2013-01-01

    Optical imperfections, misalignments, aberrations, and even dust can significantly limit sensitivity in high-contrast imaging systems such as coronagraphs. An upstream deformable mirror (DM) in the pupil can be used to correct or compensate for these flaws, either to enhance Strehl ratio or suppress residual coronagraphic halo. Measurement of the phase and amplitude of the starlight halo at the science camera is essential for determining the DM shape that compensates for any non-common-path (NCP) wavefront errors. Using DM displacement ripples to create a series of probe and anti-halo speckles in the focal plane has been proposed for space-based coronagraphs and successfully demonstrated in the lab. We present the theory and first on-sky demonstration of a technique to measure the complex halo using the rapidly-changing residual atmospheric speckles at the 6.5m MMT telescope using the Clio mid-IR camera. The AO system's wavefront sensor (WFS) measurements are used to estimate the residual wavefront, allowing ...

  2. Rise of the machines: first year operations of the Robo-AO visible-light laser-adaptive optics instrument

    CERN Document Server

    Baranec, Christoph; Law, Nicholas M; Ramaprakash, A N; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Dekany, Richard; Kulkarni, Shrinivas; Punnadi, Sujit; Smith, Roger

    2013-01-01

    Robo-AO is the first autonomous laser adaptive optics system and science instrument operating on sky. With minimal human oversight, the system robotically executes large scale surveys, monitors long-term astrophysical dynamics and characterizes newly discovered transients, all at the visible diffraction limit. The average target-to target operational overhead, including slew time, is a mere 86 s, enabling up to ~20 observations per hour. The first of many envisioned systems went live in June 2012, and has since finished 78 nights of science observing at the Palomar Observatory 60-inch (1.5 m) telescope, with over 9,000 robotic observations executed as of August 2013. The system will be augmented in 2014 with a low-noise wide field infrared camera, which will double as a tip-tilt sensor, to widen the spectral bandwidth of observations, increase available sky coverage as well as enable deeper visible imaging using adaptive-optics sharpened infrared tip-tilt guide sources.

  3. Rise of The Machines: First Year Operations of The Robo-AO Visible-Light Laser-Adaptive-Optics Instrument

    Science.gov (United States)

    Baranec, C.; Riddle, R.; Law, N.; Ramaprakash, A. N.; Tendulkar, S.; Hogstrom, K.; Bui, K.; Burse, M.; Chordia, P.; Das, H.; Dekany, R.

    2013-09-01

    Robo-AO is the first autonomous laser adaptive optics system and science instrument operating on sky. With minimal human oversight, the system robotically executes large scale surveys, monitors long-term astrophysical dynamics and characterizes newly discovered transients, all at the visible diffraction limit. The average target-to-target operational overhead, including slew time, is a mere 86 s, enabling up to ~200 observations per night. The first of many envisioned systems went live in June 2012, and has since finished 51 nights of science observing at the Palomar Observatory 60-inch (1.5 m) telescope, with over 5,600 robotic observations executed as of March 2013. The system will be augmented in late 2013 with a low-noise wide field infrared camera, which will double as a tip-tilt sensor, to widen the spectral bandwidth of observations, increase available sky coverage as well as enable deeper visible imaging using adaptive-optics sharpened infrared tip-tilt guide sources.

  4. Adaptive search techniques for problems in vehicle routing, part I: A survey

    Directory of Open Access Journals (Sweden)

    Kritzinger Stefanie

    2015-01-01

    Full Text Available Research in the field of vehicle routing often focused on finding new ideas and concepts in the development of fast and efficient algorithms for an improved solution process. Early studies introduce static tailor-made strategies, but trends show that algorithms with generic adaptive policies - which emerged in the past years - are more efficient to solve complex vehicle routing problems. In this first part of the survey, we present an overview of recent literature dealing with adaptive or guided search techniques for problems in vehicle routing.

  5. Data-based online nonlinear extremum-seeker for wavefront sensorless adaptive optics OCT (Conference Presentation)

    Science.gov (United States)

    Jian, Yifan; Verstraete, Hans R. G. W.; Heisler, Morgan; Ju, Myeong Jin; Wahl, Daniel J.; Bliek, Laurens; Kalkman, Jeroen; Bonora, Stefano; Verhaegen, Michel; Sarunic, Marinko V.

    2017-02-01

    Adaptive optics has been successfully applied to cellular resolution imaging of the retina, enabling visualization of the characteristic mosaic patterns of the outer retina. Wavefront sensorless adaptive optics (WSAO) is a novel technique that facilitates high resolution ophthalmic imaging; it replaces the Hartmann-Shack Wavefront Sensor with an image-driven optimization algorithm and mitigates some the challenges encountered with sensor-based designs. However, WSAO generally requires longer time to perform aberrations correction than the conventional closed-loop adaptive optics. When used for in vivo retinal imaging applications, motion artifacts during the WSAO optimization process will affect the quality of the aberration correction. A faster converging optimization scheme needs to be developed to account for rapid temporal variation of the wavefront and continuously apply corrections. In this project, we investigate the Databased Online Nonlinear Extremum-seeker (DONE), a novel non-linear multivariate optimization algorithm in combination with in vivo human WSAO OCT imaging. We also report both hardware and software updates of our compact lens based WSAO 1060nm swept source OCT human retinal imaging system, including real time retinal layer segmentation and tracking (ILM and RPE), hysteresis correction for the multi-actuator adaptive lens, precise synchronization control for the 200kHz laser source, and a zoom lens unit for rapid switching of the field of view. Cross sectional images of the retinal layers and en face images of the cone photoreceptor mosaic acquired in vivo from research volunteers before and after WSAO optimization are presented.

  6. High-speed adaptive optics line scan confocal retinal imaging for human eye

    Science.gov (United States)

    Wang, Xiaolin; Zhang, Yuhua

    2017-01-01

    Purpose Continuous and rapid eye movement causes significant intraframe distortion in adaptive optics high resolution retinal imaging. To minimize this artifact, we developed a high speed adaptive optics line scan confocal retinal imaging system. Methods A high speed line camera was employed to acquire retinal image and custom adaptive optics was developed to compensate the wave aberration of the human eye’s optics. The spatial resolution and signal to noise ratio were assessed in model eye and in living human eye. The improvement of imaging fidelity was estimated by reduction of intra-frame distortion of retinal images acquired in the living human eyes with frame rates at 30 frames/second (FPS), 100 FPS, and 200 FPS. Results The device produced retinal image with cellular level resolution at 200 FPS with a digitization of 512×512 pixels/frame in the living human eye. Cone photoreceptors in the central fovea and rod photoreceptors near the fovea were resolved in three human subjects in normal chorioretinal health. Compared with retinal images acquired at 30 FPS, the intra-frame distortion in images taken at 200 FPS was reduced by 50.9% to 79.7%. Conclusions We demonstrated the feasibility of acquiring high resolution retinal images in the living human eye at a speed that minimizes retinal motion artifact. This device may facilitate research involving subjects with nystagmus or unsteady fixation due to central vision loss. PMID:28257458

  7. Adaptive Optics Facility: control strategy and first on-sky results of the acquisition sequence

    Science.gov (United States)

    Madec, P.-Y.; Kolb, J.; Oberti, S.; Paufique, J.; La Penna, P.; Hackenberg, W.; Kuntschner, H.; Argomedo, J.; Kiekebusch, M.; Donaldson, R.; Suarez, M.; Arsenault, R.

    2016-07-01

    The Adaptive Optics Facility is an ESO project aiming at converting Yepun, one of the four 8m telescopes in Paranal, into an adaptive telescope. This is done by replacing the current conventional secondary mirror of Yepun by a Deformable Secondary Mirror (DSM) and attaching four Laser Guide Star (LGS) Units to its centerpiece. In the meantime, two Adaptive Optics (AO) modules have been developed incorporating each four LGS WaveFront Sensors (WFS) and one tip-tilt sensor used to control the DSM at 1 kHz frame rate. The four LGS Units and one AO module (GRAAL) have already been assembled on Yepun. Besides the technological challenge itself, one critical area of AOF is the AO control strategy and its link with the telescope control, including Active Optics used to shape M1. Another challenge is the request to minimize the overhead due to AOF during the acquisition phase of the observation. This paper presents the control strategy of the AOF. The current control of the telescope is first recalled, and then the way the AO control makes the link with the Active Optics is detailed. Lab results are used to illustrate the expected performance. Finally, the overall AOF acquisition sequence is presented as well as first results obtained on sky with GRAAL.

  8. High-speed adaptive optics line scan confocal retinal imaging for human eye.

    Science.gov (United States)

    Lu, Jing; Gu, Boyu; Wang, Xiaolin; Zhang, Yuhua

    2017-01-01

    Continuous and rapid eye movement causes significant intraframe distortion in adaptive optics high resolution retinal imaging. To minimize this artifact, we developed a high speed adaptive optics line scan confocal retinal imaging system. A high speed line camera was employed to acquire retinal image and custom adaptive optics was developed to compensate the wave aberration of the human eye's optics. The spatial resolution and signal to noise ratio were assessed in model eye and in living human eye. The improvement of imaging fidelity was estimated by reduction of intra-frame distortion of retinal images acquired in the living human eyes with frame rates at 30 frames/second (FPS), 100 FPS, and 200 FPS. The device produced retinal image with cellular level resolution at 200 FPS with a digitization of 512×512 pixels/frame in the living human eye. Cone photoreceptors in the central fovea and rod photoreceptors near the fovea were resolved in three human subjects in normal chorioretinal health. Compared with retinal images acquired at 30 FPS, the intra-frame distortion in images taken at 200 FPS was reduced by 50.9% to 79.7%. We demonstrated the feasibility of acquiring high resolution retinal images in the living human eye at a speed that minimizes retinal motion artifact. This device may facilitate research involving subjects with nystagmus or unsteady fixation due to central vision loss.

  9. Adaptive control of modal properties of optical beams using photothermal effects.

    Science.gov (United States)

    Arain, Muzammil A; Korth, William Z; Williams, Luke F; Martin, Rodica M; Mueller, Guido; Tanner, D B; Reitze, David H

    2010-02-01

    We present an experimental demonstration of adaptive control of modal properties of optical beams. The control is achieved via heat-induced photothermal actuation of transmissive optical elements. We apply the heat using four electrical heaters in thermal contact with the element. The system is capable of controlling both symmetrical and astigmatic aberrations providing a powerful means for in situ correction and control of thermal aberrations in high power laser systems. We demonstrate a tunable lens with a focusing power varying from minus infinity to -10 m along two axes using SF57 optical glass. Applications of the proposed system include laser material processing, thermal compensation of high laser power radiation, and optical beam steering.

  10. ADAPTIVE E-LEARNING TECHNIQUES IN THE DEVELOPMENT OF TEACHING ELECTRONIC PORTFOLIO – A SURVEY

    Directory of Open Access Journals (Sweden)

    DEKSON D.E.,

    2010-09-01

    Full Text Available Emerging technologies of communication and information influence the society, in particular the educational system in new directions. Media based educational systems are becoming more popular today and vast student population rely on this for learning. In the technologically emerging education system, it is necessary to have an e-learning system which can understand the learner’s preferences and make attempts to deliver content accordingly. It has become a challenging task to understand the learning preferences of the learners and adapt a method to offer content to suit the learning styles of the learners. Many educationists and researchers in education have made attempts and conducted research on delivering adaptive content. The learners of today are on the look out for content that would suit them in terms of their taste, understanding level, learning curve, own preferences and their personal traits. Thelearning process would be more efficient if we could satisfy the above needs of the learners. This paper makes a survey of the various means of offering adaptive content in an e-learning environment and explores the possible ways of achieving adaptability in learning systems. We conduct a study on the various models of adaptive contentdelivery system and propose newer methods of delivering adaptive content in an e-learning environment.

  11. Translation, cultural adaptation and validation of the Kidney Disease Knowledge Survey (KiKS) to Spanish

    OpenAIRE

    Mota Anaya, Evelin; Wright Nunes, Julie; Mayta Tristán, Percy

    2016-01-01

    Introduction—Chronic kidney disease (CKD) affects 50 million people globally. Several studies show the importance of implementing interventions that enhance patients' knowledge about their disease. In 2011, the Kidney Disease Knowledge Survey (KiKS) was developed, a questionnaire that assesses the specific knowledge about CKD in pre-dialysis patients. Objective—To translate to Spanish, culturally adapt and validate the questionnaire KiKS in a population of patients with pre-dia...

  12. Algorithm for localized adaptive diffuse optical tomography and its application in bioluminescence tomography

    Science.gov (United States)

    Naser, Mohamed A.; Patterson, Michael S.; Wong, John W.

    2014-04-01

    A reconstruction algorithm for diffuse optical tomography based on diffusion theory and finite element method is described. The algorithm reconstructs the optical properties in a permissible domain or region-of-interest to reduce the number of unknowns. The algorithm can be used to reconstruct optical properties for a segmented object (where a CT-scan or MRI is available) or a non-segmented object. For the latter, an adaptive segmentation algorithm merges contiguous regions with similar optical properties thereby reducing the number of unknowns. In calculating the Jacobian matrix the algorithm uses an efficient direct method so the required time is comparable to that needed for a single forward calculation. The reconstructed optical properties using segmented, non-segmented, and adaptively segmented 3D mouse anatomy (MOBY) are used to perform bioluminescence tomography (BLT) for two simulated internal sources. The BLT results suggest that the accuracy of reconstruction of total source power obtained without the segmentation provided by an auxiliary imaging method such as x-ray CT is comparable to that obtained when using perfect segmentation.

  13. Adaptive Bit Rate Video Streaming Through an RF/Free Space Optical Laser Link

    Directory of Open Access Journals (Sweden)

    A. Akbulut

    2010-06-01

    Full Text Available This paper presents a channel-adaptive video streaming scheme which adjusts video bit rate according to channel conditions and transmits video through a hybrid RF/free space optical (FSO laser communication system. The design criteria of the FSO link for video transmission to 2.9 km distance have been given and adaptive bit rate video streaming according to the varying channel state over this link has been studied. It has been shown that the proposed structure is suitable for uninterrupted transmission of videos over the hybrid wireless network with reduced packet delays and losses even when the received power is decreased due to weather conditions.

  14. Experimental verification of the frozen flow atmospheric turbulence assumption with use of astronomical adaptive optics telemetry.

    Science.gov (United States)

    Poyneer, Lisa; van Dam, Marcos; Véran, Jean-Pierre

    2009-04-01

    We use closed-loop deformable mirror telemetry from Altair and Keck adaptive optics (AO) to determine whether atmospheric turbulence follows the frozen flow hypothesis. Using telemetry from AO systems, our algorithms (based on the predictive Fourier control framework) detect frozen flow >94% of the time. Usually one to three layers are detected. Between 20% and 40% of the total controllable phase power is due to frozen flow. Velocity vector RMS variability is less than 0.5 m/s (per axis) on 10-s intervals, indicating that the atmosphere is stable enough for predictive control to measure and adapt to prevailing atmospheric conditions before they change.

  15. Development of an ultra high-precision x-ray telescope with an adaptive optics system

    Science.gov (United States)

    Kitamoto, Shunji; Takano, Haruko; Saitoh, Harue; Yamamoto, Norimasa; Kohmura, Takayoshi; Suga, Kazuharu; Sekiguchi, Hiroyuki

    2003-06-01

    We are developing an ultra high precision Soft X-ray telescope. The design of the telescope is a normal incident one for 13.5 nm band using Mo/Si multilayers. Two ideas are introduced. One is the optical measurement system in order to monitor the prevision of the optics system. The other is the adaptive optics system with a deformable mirror. Using an x-ray optical separation filter, we can always monitor the deformation of the optics by optical light. With this information, we can control the deformable mirror to compensate the system deformation as a closed loop system. We confirmed that the absolute precision of the wave front sensor was less than 3 nm rms. The preicison of the deformable mirror was roughly 5 nm rms. The shape of the primary mirror was an off-axis paraboloide with an effective diameter of 80mm. This primary mirror was coated by Mo/Si multilayers. The reflectivity of the primary mirror at 13.5 nm was rnaging from 30 to 50%. The x-ray optical separation filter was made from Zr with a thicknness of ~170nm. The transmission of the filter for low energy x-ray was measured and was roughly 50% at 13.5nm.

  16. Cellular resolution volumetric in vivo retinal imaging with adaptive optics–optical coherence tomography◊

    Science.gov (United States)

    Zawadzki, Robert J.; Choi, Stacey S.; Fuller, Alfred R.; Evans, Julia W.; Hamann, Bernd; Werner, John S.

    2009-01-01

    Ultrahigh-resolution adaptive optics–optical coherence tomography (UHR-AO-OCT) instrumentation allowing monochromatic and chromatic aberration correction was used for volumetric in vivo retinal imaging of various retinal structures including the macula and optic nerve head (ONH). Novel visualization methods that simplify AO-OCT data viewing are presented, and include co-registration of AO-OCT volumes with fundus photography and stitching of multiple AO-OCT sub-volumes to create a large field of view (FOV) high-resolution volume. Additionally, we explored the utility of Interactive Science Publishing by linking all presented AO-OCT datasets with the OSA ISP software. PMID:19259248

  17. Experimentally observe the effect of spherical aberration on diffractive intraocular lens using adaptive optics

    Science.gov (United States)

    Guo, Huanqing; DeLestrange, Elie

    2015-03-01

    We first investigated the similarity in optical quality of a batch of diffractive intraocular lenses (DIOLs), providing experimental evidence for one DIOL as representative of a batch. Using adaptive optics, we then evaluated one DIOL under different levels of Zernike spherical aberration (SA) by applying both a point spread function test and a psychophysical visual acuity test. We found that for small aperture size SA has the effect of shifting the through-focus curve of DIOL. Also, for a relatively large aperture size, it has different effects on the distant and near foci.

  18. Thermo-optically driven adaptive mirror based on thermal expansion: preparation and resolution

    Science.gov (United States)

    Reinert, Felix; Lüthy, W.

    2005-12-01

    A thermo-optically driven adaptive mirror is presented. It is based on the thermal expansion of a thin film heated with a light pattern. We describe a procedure for the preparation of a silicon elastomer with a high-quality optical surface. This material, Sylgard 184, has a high linear thermal expansion coefficient of 3.1μ10-4 K-1. Surface modulations are recorded in an interferometer. Modulations of 350 nm result at an intensity of 370 mW/cm2. The resolution is measured with a line pattern. The contrast drops to 30 % at 1.6 line pairs per millimeter (lp/mm).

  19. An adaptive filter for studying the life cycle of optical rogue waves.

    Science.gov (United States)

    Liu, Chu; Rees, Eric J; Laurila, Toni; Jian, Shuisheng; Kaminski, Clemens F

    2010-12-06

    We present an adaptive numerical filter for analyzing fiber-length dependent properties of optical rogue waves, which are highly intense and extremely red-shifted solitons that arise during supercontinuum generation in photonic crystal fiber. We use this filter to study a data set of 1000 simulated supercontinuum pulses, produced from 5 ps pump pulses containing random noise. Optical rogue waves arise in different supercontinuum pulses at various positions along the fiber, and exhibit a lifecycle: their intensity peaks over a finite range of fiber length before declining slowly.

  20. Optical Cluster-Finding with An Adaptive Matched-Filter Technique: Algorithm and Comparison with Simulations

    CERN Document Server

    Dong, Feng; Gunn, James E; Wechsler, Risa H

    2007-01-01

    We present a modified adaptive matched filter algorithm designed to identify clusters of galaxies in wide-field imaging surveys such as the Sloan Digital Sky Survey. The cluster-finding technique is fully adaptive to imaging surveys with spectroscopic coverage, multicolor photometric redshifts, no redshift information at all, and any combination of these within one survey. It works with high efficiency in multi-band imaging surveys where photometric redshifts can be estimated with well-understood error distributions. Tests of the algorithm on realistic mock SDSS catalogs suggest that the detected sample is ~85% complete and over 90% pure for clusters with masses above 1.0*10^{14} h^{-1} M_solar and redshifts up to z=0.45. The errors of estimated cluster redshifts from maximum likelihood method are shown to be small (typically less that 0.01) over the whole redshift range with photometric redshift errors typical of those found in the Sloan survey. Inside the spherical radius corresponding to a galaxy overdensi...

  1. Optical Cluster-Finding with an Adaptive Matched-Filter Technique: Algorithm and Comparison with Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Feng; Pierpaoli, Elena; Gunn, James E.; Wechsler, Risa H.

    2007-10-29

    We present a modified adaptive matched filter algorithm designed to identify clusters of galaxies in wide-field imaging surveys such as the Sloan Digital Sky Survey. The cluster-finding technique is fully adaptive to imaging surveys with spectroscopic coverage, multicolor photometric redshifts, no redshift information at all, and any combination of these within one survey. It works with high efficiency in multi-band imaging surveys where photometric redshifts can be estimated with well-understood error distributions. Tests of the algorithm on realistic mock SDSS catalogs suggest that the detected sample is {approx} 85% complete and over 90% pure for clusters with masses above 1.0 x 10{sup 14}h{sup -1} M and redshifts up to z = 0.45. The errors of estimated cluster redshifts from maximum likelihood method are shown to be small (typically less that 0.01) over the whole redshift range with photometric redshift errors typical of those found in the Sloan survey. Inside the spherical radius corresponding to a galaxy overdensity of {Delta} = 200, we find the derived cluster richness {Lambda}{sub 200} a roughly linear indicator of its virial mass M{sub 200}, which well recovers the relation between total luminosity and cluster mass of the input simulation.

  2. Survey of energy efficient tracking and localization techniques in buildings using optical and wireless communication media

    NARCIS (Netherlands)

    Bruintjes, Tom M.; Kokkeler, André B.J.; Karagiannis, Georgios; Smit, Gerard J.M.

    2012-01-01

    This paper presents a survey of beamforming, beamsteering and mobile tracking techniques. The survey was made in the context of the SOWICI project. The aim of this project is to reduce power consumption of data exchanging devices within houses. An optical fiber network is used for data transport to

  3. The ultraviolet, optical, and infrared properties of Sloan Digital Sky Survey sources detected by GALEX

    NARCIS (Netherlands)

    Agueros, MA; Ivezic, Z; Covey, KR; Obric, M; Hao, L; Walkowicz, LM; West, AA; Vanden Berk, DE; Lupton, RH; Knapp, GR; Gunn, JE; Richards, GT; Bochanski, J; Brooks, A; Claire, M; Haggard, D; Kaib, N; Kimball, A; Gogarten, SM; Seth, A; Solontoi, M

    2005-01-01

    We discuss the ultraviolet, optical, and infrared properties of the Sloan Digital Sky Survey (SDSS) sources detected by the Galaxy Evolution Explorer ( GALEX) as part of its All-sky Imaging Survey Early Release Observations. Virtually all (> 99%) the GALEX sources in the overlap region are detected

  4. The ultraviolet, optical, and infrared properties of Sloan Digital Sky Survey sources detected by GALEX

    NARCIS (Netherlands)

    Agueros, MA; Ivezic, Z; Covey, KR; Obric, M; Hao, L; Walkowicz, LM; West, AA; Vanden Berk, DE; Lupton, RH; Knapp, GR; Gunn, JE; Richards, GT; Bochanski, J; Brooks, A; Claire, M; Haggard, D; Kaib, N; Kimball, A; Gogarten, SM; Seth, A; Solontoi, M

    We discuss the ultraviolet, optical, and infrared properties of the Sloan Digital Sky Survey (SDSS) sources detected by the Galaxy Evolution Explorer ( GALEX) as part of its All-sky Imaging Survey Early Release Observations. Virtually all (> 99%) the GALEX sources in the overlap region are detected

  5. Coherent free space optics communications over the maritime atmosphere with use of adaptive optics for beam wavefront correction.

    Science.gov (United States)

    Li, Ming; Cvijetic, Milorad

    2015-02-20

    We evaluate the performance of the coherent free space optics (FSO) employing quadrature array phase-shift keying (QPSK) modulation over the maritime atmosphere with atmospheric turbulence compensated by use of adaptive optics (AO). We have established a comprehensive FSO channel model for maritime conditions and also made a comprehensive comparison of performance between the maritime and terrestrial atmospheric links. The FSO links are modeled based on the intensity attenuation resulting from scattering and absorption effects, the log-amplitude fluctuations, and the phase distortions induced by turbulence. The obtained results show that the FSO system performance measured by the bit-error-rate (BER) can be significantly improved when the optimization of the AO system is achieved. Also, we find that the higher BER is observed in the maritime FSO channel with atmospheric turbulence, as compared to the terrestrial FSO systems if they experience the same turbulence strength.

  6. Burrell-Optical-Kepler Survey (BOKS) II: Early Variability Results

    Science.gov (United States)

    Howell, Steve B.; Feldmeier, J.; von Braun, K.; Everett, M.; Mihos, C.; Harding, P.; Knox, C.; Sherry, W.; Lee, T.; Ciardi, D.; Rudick, C.; Proctor, M.; van Belle, G.

    2006-12-01

    We present preliminary results for the photometric time-series data obtained with the BOKS survey (see BOKS I poster Feldmeier et al.). The BOKS survey covers about 1 square degree in the constellation of Cygnus. We obtained nearly 2000 SDSS r-band images spanning a total time period of 39 days. Each point source in our BOKS survey is also present in the single epoch, 7-color photometric survey catalogue being produced by the NASA Discovery program Kepler mission. Light curves of approximately 60,000 point sources, spanning r=14 to 20, are examined and discussed. We will present variability demographics for the BOKS survey including characterization of the light curves into variable classes based on type, color, amplitude, and any extra-solar planet transit candidates.

  7. Extracting hysteresis from nonlinear measurement of wavefront-sensorless adaptive optics system.

    Science.gov (United States)

    Song, H; Vdovin, G; Fraanje, R; Schitter, G; Verhaegen, M

    2009-01-01

    In many scientific and medical applications wavefront-sensorless adaptive optics (AO) systems are used to correct the wavefront aberration by optimizing a certain target parameter, which is nonlinear with respect to the control signal to the deformable mirror (DM). Hysteresis is the most common nonlinearity of DMs, which can be corrected if the information about the hysteresis behavior is present. We report a general approach to extract hysteresis from the nonlinear behavior of the adaptive optical system, with the illustration of a Foucault knife test, where the voltage-intensity relationship consists of both hysteresis and some memoryless nonlinearity. The hysteresis extracted here can be used for modeling and linearization of the AO system.

  8. Non-common path aberration correction in an adaptive optics scanning ophthalmoscope.

    Science.gov (United States)

    Sulai, Yusufu N; Dubra, Alfredo

    2014-09-01

    The correction of non-common path aberrations (NCPAs) between the imaging and wavefront sensing channel in a confocal scanning adaptive optics ophthalmoscope is demonstrated. NCPA correction is achieved by maximizing an image sharpness metric while the confocal detection aperture is temporarily removed, effectively minimizing the monochromatic aberrations in the illumination path of the imaging channel. Comparison of NCPA estimated using zonal and modal orthogonal wavefront corrector bases provided wavefronts that differ by ~λ/20 in root-mean-squared (~λ/30 standard deviation). Sequential insertion of a cylindrical lens in the illumination and light collection paths of the imaging channel was used to compare image resolution after changing the wavefront correction to maximize image sharpness and intensity metrics. Finally, the NCPA correction was incorporated into the closed-loop adaptive optics control by biasing the wavefront sensor signals without reducing its bandwidth.

  9. Adaptive simultaneous algebraic reconstruction technique for retrieving refractive index profiles of optical fiber

    Science.gov (United States)

    Chang, Zheng; Huang, Sujuan; Wang, Tingyun; Shang, Yi; Zhang, Qianwu; Yan, Cheng; Zou, Fang

    2016-09-01

    An efficient adaptive simultaneous algebraic reconstruction technique (ASART) to calculate optical fiber refractive index profiles is proposed based on phase difference curves obtained by digital holography technique. We develop adaptive relaxation parameter (ARP) on simultaneous algebraic reconstruction technique (SART) to increase the convergence speed and improve the reconstruction accuracy. A formula of ARP is derived mathematically and multilevel scheme (MLS) is used to increase convergence speed in the first iteration. Experimental results show the proposed ASART convergences over 40% faster than SART and achieve significantly higher reconstruction accuracy. Experimental verification shows that ASART is more efficient than SART and filtered back projection in image reconstruction, especially with few projection views. The running time of ASART is much shorter than that of SART, and ASART needs fewer iteration numbers to obtain the same reconstruction effects. In addition, it can be used to measure optical fibers with various diameters that cannot be measured with S14 refractive index profiler (S14).

  10. Experience with wavefront sensor and deformable mirror interfaces for wide-field adaptive optics systems

    CERN Document Server

    Basden, A G; Bharmal, N A; Bitenc, U; Brangier, M; Buey, T; Butterley, T; Cano, D; Chemla, F; Clark, P; Cohen, M; Conan, J -M; de Cos, F J; Dickson, C; Dipper, N A; Dunlop, C N; Feautrier, P; Fusco, T; Gach, J L; Gendron, E; Geng, D; Goodsell, S J; Gratadour, D; Greenaway, A H; Guesalaga, A; Guzman, C D; Henry, D; Holck, D; Hubert, Z; Huet, J M; Kellerer, A; Kulcsar, C; Laporte, P; Roux, B Le; Looker, N; Longmore, A J; Marteaud, M; Martin, O; Meimon, S; Morel, C; Morris, T J; Myers, R M; Osborn, J; Perret, D; Petit, C; Raynaud, H; Reeves, A P; Rousset, G; Lasheras, F Sanchez; Rodriguez, M Sanchez; Santos, J D; Sevin, A; Sivo, G; Stadler, E; Stobie, B; Talbot, G; Todd, S; Vidal, F; Younger, E J

    2016-01-01

    Recent advances in adaptive optics (AO) have led to the implementation of wide field-of-view AO systems. A number of wide-field AO systems are also planned for the forthcoming Extremely Large Telescopes. Such systems have multiple wavefront sensors of different types, and usually multiple deformable mirrors (DMs). Here, we report on our experience integrating cameras and DMs with the real-time control systems of two wide-field AO systems. These are CANARY, which has been operating on-sky since 2010, and DRAGON, which is a laboratory adaptive optics real-time demonstrator instrument. We detail the issues and difficulties that arose, along with the solutions we developed. We also provide recommendations for consideration when developing future wide-field AO systems.

  11. End to end numerical simulations of the MAORY multiconjugate adaptive optics system

    CERN Document Server

    Arcidiacono, Carmelo; Bregoli, Giovanni; Diolaiti, Emiliano; Foppiani, Italo; Cosentino, Giuseppe; Lombini, Matteo; Butler, R C; Ciliegi, Paolo

    2014-01-01

    MAORY is the adaptive optics module of the E-ELT that will feed the MICADO imaging camera through a gravity invariant exit port. MAORY has been foreseen to implement MCAO correction through three high order deformable mirrors driven by the reference signals of six Laser Guide Stars (LGSs) feeding as many Shack-Hartmann Wavefront Sensors. A three Natural Guide Stars (NGSs) system will provide the low order correction. We develop a code for the end-to-end simulation of the MAORY adaptive optics (AO) system in order to obtain high-delity modeling of the system performance. It is based on the IDL language and makes extensively uses of the GPUs. Here we present the architecture of the simulation tool and its achieved and expected performance.

  12. Conjugate adaptive optics in widefield microscopy with an extended-source wavefront sensor

    CERN Document Server

    Li, Jiang; Paudel, Hari; Barankov, Roman; Bifano, Thomas; Mertz, Jerome

    2015-01-01

    Adaptive optics is a strategy to compensate for sample-induced aberrations in microscopy applications. Generally, it requires the presence of "guide stars" in the sample to serve as localized reference targets. We describe an implementation of conjugate adaptive optics that is amenable to widefield (i.e. non-scanning) microscopy, and can provide aberration corrections over potentially large fields of view without the use of guide stars. A unique feature of our implementation is that it is based on wavefront sensing with a single-shot partitioned-aperture sensor that provides large dynamic range compatible with extended samples. Combined information provided by this sensor and the imaging camera enable robust image de-blurring based on a rapid estimation of sample and aberrations obtained by closed-loop feedback. We present the theoretical principle of our technique and proof of concept experimental demonstrations.

  13. Performance simulation of the ERIS pyramid wavefront sensor module in the VLT adaptive optics facility

    Science.gov (United States)

    Quirós-Pacheco, Fernando; Agapito, Guido; Riccardi, Armando; Esposito, Simone; Le Louarn, Miska; Marchetti, Enrico

    2012-07-01

    This paper presents the performance analysis based on numerical simulations of the Pyramid Wavefront sensor Module (PWM) to be included in ERIS, the new Adaptive Optics (AO) instrument for the Adaptive Optics Facility (AOF). We have analyzed the performance of the PWM working either in a low-order or in a high-order wavefront sensing mode of operation. We show that the PWM in the high-order sensing mode can provide SR > 90% in K band using bright guide stars under median seeing conditions (0.85 arcsec seeing and 15 m/s of wind speed). In the low-order sensing mode, the PWM can sense and correct Tip-Tilt (and if requested also Focus mode) with the precision required to assist the LGS observations to get an SR > 60% and > 20% in K band, using up to a ~16.5 and ~19.5 R-magnitude guide star, respectively.

  14. Adaptive optics correction of a tunable fluidic lens for ophthalmic applications

    Science.gov (United States)

    Fuh, Yiin-Kuen; Lin, Ming-Xin

    2013-11-01

    Tunable fluidic lenses are utilizing curvature change via continuously adjusting injected liquid volumes to achieve variable-focusing properties. Nevertheless, the nature of curvature change and refractive index mismatch causes inherent spatial aberrations that severely degrade image quality. Here we present the experimental study of the aberrations in tunable fluidic lenses and use of adaptive optics to compensate for the wavefront errors. Adaptive optics based scheme is demonstrated for three injected liquid volumes, resulting in a substantial reduction of the wavefront errors from 0.42, 1.05, 1.49 to 0.20, 0.21, 0.23 μm, respectively, corresponding to the focal length tunability of 100-200 mm.

  15. Improved performance of the laser guide star adaptive optics system at Lick Observatory

    Energy Technology Data Exchange (ETDEWEB)

    An, J R; Avicola, K; Bauman, B J; Brase, J M; Campbell, E W; Carrano, C; Cooke, J B; Freeze, G J; Friedman, H W; Max, C E; Gates, E L; Gavel, D T; Kanz, V K; Kuklo, T C; Macintosh, B A; Newman, M J; Olivier, S S; Pierce, E L; Waltjen, K E; Watson, A

    1999-07-20

    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 {micro}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 {approx}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.

  16. On distributed wavefront reconstruction for large-scale adaptive optics systems.

    Science.gov (United States)

    de Visser, Cornelis C; Brunner, Elisabeth; Verhaegen, Michel

    2016-05-01

    The distributed-spline-based aberration reconstruction (D-SABRE) method is proposed for distributed wavefront reconstruction with applications to large-scale adaptive optics systems. D-SABRE decomposes the wavefront sensor domain into any number of partitions and solves a local wavefront reconstruction problem on each partition using multivariate splines. D-SABRE accuracy is within 1% of a global approach with a speedup that scales quadratically with the number of partitions. The D-SABRE is compared to the distributed cumulative reconstruction (CuRe-D) method in open-loop and closed-loop simulations using the YAO adaptive optics simulation tool. D-SABRE accuracy exceeds CuRe-D for low levels of decomposition, and D-SABRE proved to be more robust to variations in the loop gain.

  17. Adaptive channel estimation for soft decision decoding over non-Gaussian optical channel

    Science.gov (United States)

    Xiang, Jing-song; Miao, Tao-tao; Huang, Sheng; Liu, Huan-lin

    2016-10-01

    An adaptive priori likelihood ratio (LLR) estimation method is proposed over non-Gaussian channel in the intensity modulation/direct detection (IM/DD) optical communication systems. Using the nonparametric histogram and the weighted least square linear fitting in the tail regions, the LLR is estimated and used for the soft decision decoding of the low-density parity-check (LDPC) codes. This method can adapt well to the three main kinds of intensity modulation/direct detection (IM/DD) optical channel, i.e., the chi-square channel, the Webb-Gaussian channel and the additive white Gaussian noise (AWGN) channel. The performance penalty of channel estimation is neglected.

  18. Adaptive optics in multiphoton microscopy: comparison of two, three and four photon fluorescence.

    Science.gov (United States)

    Sinefeld, David; Paudel, Hari P; Ouzounov, Dimitre G; Bifano, Thomas G; Xu, Chris

    2015-11-30

    We demonstrate adaptive optics system based on nonlinear feedback from 3- and 4-photon fluorescence. The system is based on femtosecond pulses created by soliton self-frequency shift of a 1550-nm fiber-based femtosecond laser together with micro-electro-mechanical system (MEMS) phase spatial light modulator (SLM). We perturb the 1020-segment SLM using an orthogonal Walsh sequence basis set with a modified version of three-point phase shifting interferometry. We show the improvement after aberrations correction in 3-photon signal from fluorescent beads. In addition, we compare the improvement obtained in the same adaptive optical system for 2-, 3- and 4-photon fluorescence using dye pool. We show that signal improvement resulting from aberration correction grows exponentially as a function of the order of nonlinearity.

  19. Perceptual image quality in normalized LOG domain for Adaptive Optics image post-processing

    Science.gov (United States)

    Guo, Shiping; Zhang, Rongzhi; Li, Jisheng; Zou, Jianhua; Liu, Changhai; Gao, Weizhe

    2015-08-01

    Adaptive Optics together with subsequent post-processing techniques obviously improve the resolution of turbulencedegraded images in ground-based space objects detection and identification. The most common method for frame selection and stopping iteration in post-processing has always been subjective viewing of the images due to a lack of widely agreed-upon objective quality metric. Full reference metrics are not applicable for assessing the field data, no-reference metrics tend to perform poor sensitivity for Adaptive Optics images. In the present work, based on the Laplacian of Gaussian (LOG) local contrast feature, a nonlinear normalization is applied to transform the input image into a normalized LOG domain; a quantitative index is then extracted in this domain to assess the perceptual image quality. Experiments show this no-reference quality index is highly consistent with the subjective evaluation of input images for different blur degree and different iteration number.

  20. Adaptive Optics at Optical Wavelengths: Test Observations of Kyoto 3DII Connected to Subaru Telescope AO188

    Science.gov (United States)

    Matsubayashi, K.; Sugai, H.; Shimono, A.; Akita, A.; Hattori, T.; Hayano, Y.; Minowa, Y.; Takeyama, N.

    2016-09-01

    Adaptive optics (AO) enables us to observe objects with high spatial resolution, which is important in most astrophysical observations. Most AO systems are operational at near-infrared wavelengths but not in the optical range, because optical observations require a much higher performance to obtain the same Strehl ratio as near-infrared observations. Therefore, to enable AO-assisted observations at optical wavelengths, we connected the Kyoto Tridimensional Spectrograph II (Kyoto 3DII), which can perform integral field spectroscopy, to the second generation AO system of the Subaru Telescope (AO188). We developed a new beam-splitter that reflects light below 594 nm for the wavefront sensors of AO188 and transmits above 644 nm for Kyoto 3DII. We also developed a Kyoto 3DII mount at the Nasmyth focus of the Subaru Telescope. In test observations, the spatial resolution of the combined AO188-Kyoto 3DII was higher than that in natural seeing conditions, even at 6500 Å. The full width at half maximum of an undersampled (1.5 spaxels) bright guide star (7.0 mag in the V-band) was 0.″12.

  1. Optically Identified BL Lacertae Objects From the Sloan Digital Sky Survey

    Science.gov (United States)

    2007-11-02

    386 BL Lacertae candidates identified from 2860 deg2 of the Sloan Digital Sky Survey ( SDSS ) spectroscopic database. The candidates are primarily...selected to have quasi-featureless optical spectra and low proper motions as measured from SDSS and USNO-B positions; however, our ability to separate...Sky Survey ( SDSS ; York et al. 2000) and the Two-Degree Field QSO Red- shift Survey (2QZ; Boyle et al. 2000), have the potential to reveal new

  2. Predictive wavefront control for adaptive optics with arbitrary control loop delays.

    Science.gov (United States)

    Poyneer, Lisa; Véran, Jean-Pierre

    2008-07-01

    We present a modification of the closed-loop state space model for adaptive optics control that allows delays that are a noninteger multiple of the system frame rate. We derive the new forms of the predictive Fourier control Kalman filters for arbitrary delays and show that they are linear combinations of the whole-frame delay terms. This structure of the controller is independent of the delay. System stability margins and residual error variance both transition gracefully between integer-frame delays.

  3. Neptune’s zonal winds from near-IR Keck adaptive optics imaging in August 2001

    NARCIS (Netherlands)

    Martin, S.C.; De Pater, I.; Marcus, P.

    2011-01-01

    We present H-band (1.4–1.8 μm) images of Neptune with a spatial resolution of ∼0.06″, taken with the W.M. Keck II telescope using the slit-viewing camera (SCAM) of the NIRSPEC instrument backed with Adaptive Optics. Images with 60-second integration times span 4 hours each on UT 20 and 21 August, 20

  4. Neptune’s zonal winds from near-IR Keck adaptive optics imaging in August 2001

    NARCIS (Netherlands)

    Martin, S.C.; De Pater, I.; Marcus, P.

    2011-01-01

    We present H-band (1.4–1.8 μm) images of Neptune with a spatial resolution of ∼0.06″, taken with the W.M. Keck II telescope using the slit-viewing camera (SCAM) of the NIRSPEC instrument backed with Adaptive Optics. Images with 60-second integration times span 4 hours each on UT 20 and 21 August,

  5. Adaptive Optics Assisted 3D spectroscopy observations for black hole mass measurements

    OpenAIRE

    Pastorini, Guia

    2006-01-01

    The very high spatial resolution provided by Adaptive Optics assisted spectroscopic observations at 8m-class telescopes (e.g. with SINFONI at the VLT) will allow to greatly increase the number of direct black hole (BH) mass measurements which is currently very small. This is a fundamental step to investigate the tight link between galaxy evolution and BH growth, revealed by the existing scaling relations between $M_{BH}$ and galaxy structural parameters. I present preliminary results from SIN...

  6. [Survey adaptation for bio-behavioural surveillance of HIV in Chilean female sex workers].

    Science.gov (United States)

    Carvajal, Bielka; Stuardo, Valeria; Manríquez, José Manuel; Belmar, Julieta; Folch, Cinta

    2017-04-12

    To adapt a behavioural questionnaire for second-generation HIV/AIDS surveillance in female sex workers (FSWs) in the Metropolitan Region, Chile. Qualitative study of instruments validation. A Spanish instrument adapted in Catalonia was validated through a translation and back-translation of the original version. The content validity was determined through a modified Delphi method, via FSW and HIV experts representing community, political and institutional levels. Applicability aspects were determined by the application of the questionnaire to FSW in the Metropolitan Region. The questionnaire, drafted in Spain, was successfully adapted to Chilean Spanish. The content validity process enabled sections to be created that address HIV in FSWs. The adapted questionnaire takes less than 15minutes to complete, which makes it usable in fieldwork. The 61 women surveyed came from different countries (all were Latin Americans) and had different educational levels; all this enabled potential applicability problems to be detected. The adapted questionnaire for Chile contains all the UNAIDS indicators for FSWs, as well as the recommended indicators of Family Health International for bio-behavioural surveillance. Said questionnaire serves as a tool for second-generation HIV/other STD surveillance and further contributes to preventive policies in Chilean FSWs. Copyright © 2016 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. MAD Adaptive Optics Imaging of High Luminosity Quasars: A Pilot Project

    CERN Document Server

    Liuzzo, E; Paiano, S; Treves, A; Uslenghi, M; Arcidiacono, C; Baruffolo, A; Diolaiti, E; Farinato, J; Lombini, M; Moretti, A; Ragazzoni, R; Brast, R; Donaldson, R; Kolb, J; Marchetti, E; Tordo, S

    2016-01-01

    We present near-IR images of five luminous quasars at z~2 and one at z~4 obtained with an experimental adaptive optics instrument at the ESO Very Large Telescope. The observations are part of a program aimed at demonstrating the capabilities of multi-conjugated adaptive optics imaging combined with the use of natural guide stars for high spatial resolution studies on large telescopes. The observations were mostly obtained under poor seeing conditions but in two cases. In spite of these non optimal conditions, the resulting images of point sources have cores of FWHM ~0.2 arcsec. We are able to characterize the host galaxy properties for 2 sources and set stringent upper limits to the galaxy luminosity for the others. We also report on the expected capabilities for investigating the host galaxies of distant quasars with adaptive optics systems coupled with future Extremely Large Telescopes. Detailed simulations show that it will be possible to characterize compact (2-3 kpc) quasar host galaxies for QSOs at z = ...

  8. Adaptive optics compensation of atmospheric turbulence: the past, the present, and the promise

    Science.gov (United States)

    Tyson, Robert K.

    1994-06-01

    An overview of adaptive optics systems development is presented with emphasis on its power to compensate for atmospheric turbulence in imaging and laser propagation. A brief history from the conceptual thinking in the 1950s through laboratory implementation in the 1970s to practical reality in the 1990s will be covered. With ongoing research to solve the problem of atmospheric anisoplanatism, the use of artificial guide stars has become as a prominent point of discussion. The understanding of the artificial guide star phenomena and advances in laser technology are bringing systems from the research and technology development mode into systems with scientific utility. Conflicting technical limitations of guide star brightness, laser psoower, and compensation spatial frequency are traded to achieve the most scientific benefit with the least cost. a summary ore recent results from operating adaptive optics systems in observatories around the world will be followed by a brief look at the future promise of adaptive optics in the commercia sector, including requirements of mass market systems for the amateur astronomer.

  9. Integration and bench testing for the GRAVITY Coudé IR adaptive optics (CIAO) wavefront sensor

    Science.gov (United States)

    Deen, C.; Yang, P.; Huber, A.; Suarez-Valles, M.; Hippler, S.; Brandner, W.; Gendron, E.; Clénet, Y.; Kendrew, S.; Glauser, A.; Klein, R.; Laun, W.; Lenzen, R.; Neumann, U.; Panduro, J.; Ramos, J.; Rohloff, R.-R.; Salzinger, A.; Zimmerman, N.; Henning, T.; Perraut, K.; Perrin, G.; Straubmeier, C.; Amorim, A.; Eisenhauer, F.

    2014-08-01

    GRAVITY, a second generation instrument for the Very Large Telescope Interferometer (VLTI), will provide an astrometric precision of order 10 micro-arcseconds, an imaging resolution of 4 milli-arcseconds, and low/medium resolution spectro-interferometry. These improvements to the VLTI represent a major upgrade to its current infrared interferometric capabilities, allowing detailed study of obscured environments (e.g. the Galactic Center, young dusty planet-forming disks, dense stellar cores, AGN, etc...). Crucial to the final performance of GRAVITY, the Coudé IR Adaptive Optics (CIAO) system will correct for the effects of the atmosphere at each of the VLT Unit Telescopes. CIAO consists of four new infrared Shack-Hartmann wavefront sensors (WFS) and associated real-time computers/software which will provide infrared wavefront sensing from 1.45-2.45 microns, allowing AO corrections even in regions where optically bright reference sources are scarce. We present here the latest progress on the GRAVITY wavefront sensors. We describe the adaptation and testing of a light-weight version of the ESO Standard Platform for Adaptive optics Real Time Applications (SPARTA-Light) software architecture to the needs of GRAVITY. We also describe the latest integration and test milestones for construction of the initial wave front sensor.

  10. Clear widens the field for observations of the Sun with multi-conjugate adaptive optics

    Science.gov (United States)

    Schmidt, Dirk; Gorceix, Nicolas; Goode, Philip R.; Marino, Jose; Rimmele, Thomas; Berkefeld, Thomas; Wöger, Friedrich; Zhang, Xianyu; Rigaut, François; von der Lühe, Oskar

    2017-01-01

    The multi-conjugate adaptive optics (MCAO) pathfinder Clear on the New Solar Telescope in Big Bear Lake has provided the first-ever MCAO-corrected observations of the Sun that show a clearly and visibly widened corrected field of view compared to quasi-simultaneous observations with classical adaptive optics (CAO) correction. Clear simultaneously uses three deformable mirrors, each conjugated to a different altitude, to compensate for atmospheric turbulence. While the MCAO correction was most effective over an angle that is approximately three times wider than the angle that was corrected by CAO, the full 53'' field of view did benefit from MCAO correction. We further demonstrate that ground-layer-only correction is attractive for solar observations as a complementary flavor of adaptive optics for observational programs that require homogenous seeing improvement over a wide field rather than diffraction-limited resolution. We show illustrative images of solar granulation and of a sunspot obtained on different days in July 2016, and present a brief quantitative analysis of the generalized Fried parameters of the images. The movies associated to Fig. 1 are available at http://www.aanda.org

  11. Validation Through Simulations of a Cn2 Profiler for the ESO/VLT Adaptive Optics Facility

    CERN Document Server

    Garcia-Rissmann, A; Kolb, J; Louarn, M Le; Madec, P -Y; Neichel, B

    2015-01-01

    The Adaptive Optics Facility (AOF) project envisages transforming one of the VLT units into an adaptive telescope and providing its ESO (European Southern Observatory) second generation instruments with turbulence corrected wavefronts. For MUSE and HAWK-I this correction will be achieved through the GALACSI and GRAAL AO modules working in conjunction with a 1170 actuators Deformable Secondary Mirror (DSM) and the new Laser Guide Star Facility (4LGSF). Multiple wavefront sensors will enable GLAO and LTAO capabilities, whose performance can greatly benefit from a knowledge about the stratification of the turbulence in the atmosphere. This work, totally based on end-to-end simulations, describes the validation tests conducted on a Cn2 profiler adapted for the AOF specifications. Because an absolute profile calibration is strongly dependent on a reliable knowledge of turbulence parameters r0 and L0, the tests presented here refer only to normalized output profiles. Uncertainties in the input parameters inherent t...

  12. The CFH Optical PDCS Survey (COP) First results

    CERN Document Server

    Adami, C; Mazure, A; Castander, F J; Nichol, R; Ulmer, M P; Postman, M; Lubin, L M

    1999-01-01

    We present the first results of the COP survey about the reality of the PDCS clusters, about their velocity dispersions and dynamic and about the periodicity of the structures along the line of sight.

  13. Transverse Pupil Shifts for Adaptive Optics Non-Common Path Calibration

    Science.gov (United States)

    Bloemhof, Eric E.

    2011-01-01

    A simple new way of obtaining absolute wavefront measurements with a laboratory Fizeau interferometer was recently devised. In that case, the observed wavefront map is the difference of two cavity surfaces, those of the mirror under test and of an unknown reference surface on the Fizeau s transmission flat. The absolute surface of each can be determined by applying standard wavefront reconstruction techniques to two grids of absolute surface height differences of the mirror under test, obtained from pairs of measurements made with slight transverse shifts in X and Y. Adaptive optics systems typically provide an actuated periscope between wavefront sensor (WFS) and commonmode optics, used for lateral registration of deformable mirror (DM) to WFS. This periscope permits independent adjustment of either pupil or focal spot incident on the WFS. It would be used to give the required lateral pupil motion between common and non-common segments, analogous to the lateral shifts of the two phase contributions in the lab Fizeau. The technique is based on a completely new approach to calibration of phase. It offers unusual flexibility with regard to the transverse spatial frequency scales probed, and will give results quite quickly, making use of no auxiliary equipment other than that built into the adaptive optics system. The new technique may be applied to provide novel calibration information about other optical systems in which the beam may be shifted transversely in a controlled way.

  14. New adaptive optics control strategy for petawatt-class laser chains

    Science.gov (United States)

    Varkentina, N.; Dovillaire, G.; Legrand, J.; Beaugrand, G.; Stefanon, I.; Treimany, P.; Levecq, X.

    2017-08-01

    A new generation of ultra-high intensity femtosecond petawatt- and above-class lasers requires new approaches to wavefront corrections. New challenges for adaptive optics consist in overcoming the constraints of potentially bigger diameters, larger amplitude aberrations, faster optics, higher risk of damaging optical components and faster and easier maintenance. Here we present a new technology of a mechanical deformable mirror, which has a large stroke, high temporal stability, low hysteresis, no printthrough effect, easy, safe and fast maintenance and an operating frequency up to 10 Hz. We propose the full correction of the final focal spot in the target chamber by a combination of a standard adaptive optics system, a simple focal plane camera and a phase retrieval correction process. We test the reliability of the correction system in terms of intensity variation and wavefront stability. We further verify correction robustness of the method on a large spectral bandwidth and finally perform a focal spot correction on a terawatt laser system in both low and high-power regimes.

  15. Fast binarized time-reversed adapted-perturbation (b-TRAP) optical focusing inside scattering media

    CERN Document Server

    Ma, Cheng; Liu, Yan; Wang, Lihong V

    2015-01-01

    Light scattering inhibits high-resolution optical imaging, manipulation and therapy deep inside biological tissue by preventing focusing. To form deep foci, wavefront-shaping and time-reversal techniques that break the optical diffusion limit have been developed. For in vivo applications, such focusing must provide high gain, high speed, and a large number of spatial modes. However, none of the previous techniques meet these requirements simultaneously. Here, we overcome this challenge by rapidly measuring the perturbed optical field within a single camera exposure followed by adaptively time-reversing the phase-binarized perturbation. Consequently, a phase-conjugated wavefront is synthesized within a millisecond, two orders of magnitude shorter than the digitally achieved record. We demonstrated real-time focusing in dynamic scattering media, and extended laser speckle contrast imaging to new depths. The unprecedented combination of fast response, high gain, and large mode count makes this work a major strid...

  16. Fabrication of two-dimensional micro patterns for adaptive optics by using laser interference lithography

    Science.gov (United States)

    Li, Xinghui; Cai, Yindi; Aihara, Ryo; Shimizu, Yuki; Ito, So; Gao, Wei

    2015-07-01

    This paper presents a fabrication method of two-dimensional micro patterns for adaptive optics with a micrometric or sub-micrometric period to be used for fabrication of micro lens array or two-dimensional diffraction gratings. A multibeam two-axis Lloyd's mirror interferometer is employed to carry out laser interference lithography for the fabrication of two-dimensional grating structures. In the proposed instrument, the optical setup consists of a light source providing a laser beam, a multi-beam generator, two plane mirrors to generate a two-dimensional XY interference pattern and a substrate on which the XY interference pattern is to be exposed. In this paper, pattern exposure tests are carried out by the developed optical configuration optimized by computer simulations. Some experimental results of the XY pattern fabrication will be reported.

  17. Affine nonmagnetic transformation optics and its application to a practical bending adapter design

    CERN Document Server

    Xu, Hongyi; Yu, Tianyuan; Barbastathis, George; Sun, Handong

    2011-01-01

    One of the bottlenecks that limit the transition of transformation-optics devices from concepts to practical use is the nonunit magnetic permeability generally required from a mathematical transformation. Simple renormalization of permeability, as used in many previous designs and experiments, introduces impedance mismatch and thus degrades the functional photonic performance. Here we propose an area-preserving affine coordinate transformation as a general method to solve this problem. Ideal transformation-optics functions can be preserved while nonmagnetism is achieved. As a specific example, we illustrate how to apply this affine method into the design of a two-dimensional electromagnetic beam bending adapter. Concerns related to fabrication, such as anisotropy degree and bending angles, are fully discussed. Our study is a significant step toward practical use of ideal transformation optics devices that can be implemented directly with existing dielectric materials.

  18. Lick Observatory's Shane telescope adaptive optics system (ShaneAO): research directions and progress

    Science.gov (United States)

    Gavel, Donald T.; Kupke, Renate; Rudy, Alexander R.; Srinath, Srikar; Dillon, Daren; Poyneer, Lisa A.

    2016-07-01

    We present a review of the ongoing research activity surrounding the adaptive optics system at the Shane telescope (ShaneAO) particularly the R&D efforts on the technology and algorithms for that will advance AO into wider application for astronomy. We are pursuing the AO challenges for whole sky coverage diffraction-limited correction down to visible science wavelengths. This demands high-order wavefront correction and bright artificial laser beacons. We present recent advancements in the development of MEMS based AO correction, woofer-tweeter architecture, wind-predictive wavefront control algorithms, atmospheric characterization, and a pulsed fiber amplifier guide star laser tuned for optical pumping of the sodium layer. We present the latest on-sky results from the new AO system and present status and experimental plans for the optical pumping guide star laser.

  19. Adaptive coded spreading OFDM signal for dynamic-λ optical access network

    Science.gov (United States)

    Liu, Bo; Zhang, Lijia; Xin, Xiangjun

    2015-12-01

    This paper proposes and experimentally demonstrates a novel adaptive coded spreading (ACS) orthogonal frequency division multiplexing (OFDM) signal for dynamic distributed optical ring-based access network. The wavelength can be assigned to different remote nodes (RNs) according to the traffic demand of optical network unit (ONU). The ACS can provide dynamic spreading gain to different signals according to the split ratio or transmission length, which offers flexible power budget for the network. A 10×13.12 Gb/s OFDM access with ACS is successfully demonstrated over two RNs and 120 km transmission in the experiment. The demonstrated method may be viewed as one promising for future optical metro access network.

  20. Clinical Validation of a Smartphone-Based Adapter for Optic Disc Imaging in Kenya.

    Science.gov (United States)

    Bastawrous, Andrew; Giardini, Mario Ettore; Bolster, Nigel M; Peto, Tunde; Shah, Nisha; Livingstone, Iain A T; Weiss, Helen A; Hu, Sen; Rono, Hillary; Kuper, Hannah; Burton, Matthew

    2016-02-01

    Visualization and interpretation of the optic nerve and retina are essential parts of most physical examinations. To design and validate a smartphone-based retinal adapter enabling image capture and remote grading of the retina. This validation study compared the grading of optic nerves from smartphone images with those of a digital retinal camera. Both image sets were independently graded at Moorfields Eye Hospital Reading Centre. Nested within the 6-year follow-up (January 7, 2013, to March 12, 2014) of the Nakuru Eye Disease Cohort in Kenya, 1460 adults (2920 eyes) 55 years and older were recruited consecutively from the study. A subset of 100 optic disc images from both methods were further used to validate a grading app for the optic nerves. Data analysis was performed April 7 to April 12, 2015. Vertical cup-disc ratio for each test was compared in terms of agreement (Bland-Altman and weighted κ) and test-retest variability. A total of 2152 optic nerve images were available from both methods (also 371 from the reference camera but not the smartphone, 170 from the smartphone but not the reference camera, and 227 from neither the reference camera nor the smartphone). Bland-Altman analysis revealed a mean difference of 0.02 (95% CI, -0.21 to 0.17) and a weighted κ coefficient of 0.69 (excellent agreement). The grades of an experienced retinal photographer were compared with those of a lay photographer (no health care experience before the study), and no observable difference in image acquisition quality was found. Nonclinical photographers using the low-cost smartphone adapter were able to acquire optic nerve images at a standard that enabled independent remote grading of the images comparable to those acquired using a desktop retinal camera operated by an ophthalmic assistant. The potential for task shifting and the detection of avoidable causes of blindness in the most at-risk communities makes this an attractive public health intervention.

  1. High-Contrast Imaging using Adaptive Optics for Extrasolar Planet Detection

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Julia Wilhelmsen [Univ. of California, Davis, CA (United States)

    2006-01-01

    Direct imaging of extrasolar planets is an important, but challenging, next step in planetary science. Most planets identified to date have been detected indirectly--not by emitted or reflected light but through the effect of the planet on the parent star. For example, radial velocity techniques measure the doppler shift in the spectrum of the star produced by the presence of a planet. Indirect techniques only probe about 15% of the orbital parameter space of our solar system. Direct methods would probe new parameter space, and the detected light can be analyzed spectroscopically, providing new information about detected planets. High contrast adaptive optics systems, also known as Extreme Adaptive Optics (ExAO), will require contrasts of between 10-6 and 10-7 at angles of 4-24 λ/D on an 8-m class telescope to image young Jupiter-like planets still warm with the heat of formation. Contrast is defined as the intensity ratio of the dark wings of the image, where a planet might be, to the bright core of the star. Such instruments will be technically challenging, requiring high order adaptive optics with > 2000 actuators and improved diffraction suppression. Contrast is ultimately limited by residual static wavefront errors, so an extrasolar planet imager will require wavefront control with an accuracy of better than 1 nm rms within the low- to mid-spatial frequency range. Laboratory demonstrations are critical to instrument development. The ExAO testbed at the Laboratory for Adaptive Optics was designed with low wavefront error and precision optical metrology, which is used to explore contrast limits and develop the technology needed for an extrasolar planet imager. A state-of-the-art, 1024-actuator micro-electrical-mechanical-systems (MEMS) deformable mirror was installed and characterized to provide active wavefront control and test this novel technology. I present 6.5 x 10-8 contrast measurements with a prolate shaped pupil and

  2. Fibre optics overhead lines: A state-of-the-art survey

    Energy Technology Data Exchange (ETDEWEB)

    Madge, R.C.; Krishnasamy, S.G.

    1991-12-01

    A survey was conducted to gather information on installation, operating experience, economic benefits, and other outstanding issues relating to the use of fiber optic cables as an integral part of power transmission lines. The survey focused on Canadian electric utilities but was also extended to Japan and the USA, where fiber optic cables have been in use considerably longer than in Canada. The fiber optic cables commonly used in overhead power lines can be divided into 3 major groups: composite fiber optic ground wires (OPGW), all-dielectric self-supporting (ADSS) cables, and fiber optic cables lashed to or wrapped around a metallic carrier. Canadian utilities lag significantly behind American and Japanese utilities in installed lengths of fiber optic cables of all kinds. Planned installations over the next several years will improve the Canadian situation. This delayed use may be partly due to the large distances between population and economic centers, resulting in high installation costs. Only 4 of the 13 survey participants indicated problems with use of the cables. These problems were related to improper cable design, improper performance specifications, and installation or operational deficiencies. The survey showed that OPGW and ADSS cables are increasingly considered for communications needs, but their use lags behind the more traditional technologies such as microwaves and power-line carriers. A number of issues were identified as real or perceived concerns to potential users, including lightning effects, aeolian vibration, environmental exposure, hardware design, tower placement, and a lack of shared experiential information. 5 refs., 3 figs., 3 tabs.

  3. Cone structure imaged with adaptive optics scanning laser ophthalmoscopy in eyes with nonneovascular age-related macular degeneration

    National Research Council Canada - National Science Library

    Zayit-Soudry, Shiri; Duncan, Jacque L; Syed, Reema; Menghini, Moreno; Roorda, Austin J

    2013-01-01

    To evaluate cone spacing using adaptive optics scanning laser ophthalmoscopy (AOSLO) in eyes with nonneovascular AMD, and to correlate progression of AOSLO-derived cone measures with standard measures of macular structure...

  4. An adaptive optics aided differential optical positioning for passive orbit determination of the space debris at the geostationary orbit

    Science.gov (United States)

    Piatrou, Piotr; Rigaut, Francois

    2017-10-01

    Proliferation of space debris presents an imminent threat to all space assets. The problem is especially severe for the geostationary band of orbits (GEO) because the GEO objects never leave their orbit and, at the same time, are difficult to observe and operate due to large distance from the Earth. Under the influence of tidal forces, even passive GEO objects achieve high local velocities without vacating GEO positions, which may potentially lead to devastating collisions. Our ability to predict collisions in GEO is limited by the scarcity of the accurate orbital data, especially about the small and passive objects. The efforts to address this omission strongly rely on the ground-based optical sensors and, consequently, on the efficient space object detection and tracking techniques. In this paper we propose a passive differential optical debris tracking technique combining adaptive optics and a high accuracy astrometric references resulting in a significant improvement in the GEO object positioning accuracy. The achievable accuracy is estimated via detailed numerical simulations of two telescopes in different locations.

  5. High-resolution in-depth imaging of optically cleared thick samples using an adaptive SPIM

    Science.gov (United States)

    Masson, Aurore; Escande, Paul; Frongia, Céline; Clouvel, Grégory; Ducommun, Bernard; Lorenzo, Corinne

    2015-11-01

    Today, Light Sheet Fluorescence Microscopy (LSFM) makes it possible to image fluorescent samples through depths of several hundreds of microns. However, LSFM also suffers from scattering, absorption and optical aberrations. Spatial variations in the refractive index inside the samples cause major changes to the light path resulting in loss of signal and contrast in the deepest regions, thus impairing in-depth imaging capability. These effects are particularly marked when inhomogeneous, complex biological samples are under study. Recently, chemical treatments have been developed to render a sample transparent by homogenizing its refractive index (RI), consequently enabling a reduction of scattering phenomena and a simplification of optical aberration patterns. One drawback of these methods is that the resulting RI of cleared samples does not match the working RI medium generally used for LSFM lenses. This RI mismatch leads to the presence of low-order aberrations and therefore to a significant degradation of image quality. In this paper, we introduce an original optical-chemical combined method based on an adaptive SPIM and a water-based clearing protocol enabling compensation for aberrations arising from RI mismatches induced by optical clearing methods and acquisition of high-resolution in-depth images of optically cleared complex thick samples such as Multi-Cellular Tumour Spheroids.

  6. Development of active/adaptive lightweight optics for the next generation of telescopes

    Science.gov (United States)

    Ghigo, M.; Basso, S.; Citterio, O.; Mazzoleni, F.; Vernani, D.

    2006-02-01

    The future large optical telescopes will have such large dimensions to require innovative technical solutions either in the engineering and optical fields. Their optics will have dimensions ranging from 30 to 100 m. and will be segmented. It is necessary to develop a cost effective industrial process, fast and efficient, to create the thousands of segments neeededs to assemble the mirrors of these instruments. INAF-OAB (Astronomical Observatory of Brera) is developing with INAF-Arcetri (Florence Astronomical Observatory) a method of production of lightweight glass optics that is suitable for the manufacturing of these segments. These optics will be also probably active and therefore the segments have to be thin, light and relatively flexible. The same requirements are valid also for the secondary adaptive mirrors foreseen for these telescopes and that therefore will benefit from the same technology. The technique under investigation foresees the thermal slumping of thin glass segments using a high quality ceramic mold (master). The sheet of glass is placed onto the mold and then, by means of a suitable thermal cycle, the glass is softened and its shape is changed copying the master shape. At the end of the slumping the correction of the remaining errors will be performed using the Ion Beam Figuring technique, a non-contact deterministic technique. To reduce the time spent for the correction it will be necessary to have shape errors on the segments as small as possible. A very preliminary series of experiments already performed on reduced size segments have shown that it is possible to copy a master shape with high accuracy (few microns PV) and it is very likely that copy accuracies of 1 micron or less are possible. The paper presents in detail the concepts of the proposed process and describes our current efforts that are aimed at the production of a scaled demonstrative adaptive segment of 50 cm of diameter.

  7. Adaptive Surveying and Early Treatment of Crops with a Team of Autonomous Vehicles

    DEFF Research Database (Denmark)

    Kazmi, Wajahat; Bisgaard, Morten; Garcia-Ruiz, Francisco

    2011-01-01

    The ASETA project (acronym for Adaptive Surveying and Early treatment of crops with a Team of Autonomous vehicles) is a multi-disciplinary project combining cooperating airborne and ground-based vehicles with advanced sensors and automated analysis to implement a smart treatment of weeds in agric...... and allocation, remote sensing and 3D computer vision....... system (UAS) and unmanned ground vehicles (UGV) with advanced vision sensors for 3D and multispectral imaging. This paper presents the scientific and technological challenges in the project, which include multivehicle estimation and guidance, heterogeneous multi-agent systems, task generation...

  8. Status Update and Closed-Loop Performance of the Magellan Adaptive Optics VisAO Camera

    CERN Document Server

    Kopon, Derek; Males, Jared; Gasho, Victor; Morzinski, Katie; Follette, Katherine

    2014-01-01

    We present laboratory results of the closed-loop performance of the Magellan Adaptive Optics (AO) Adaptive Secondary Mirror (ASM), pyramid wavefront sensor (PWFS), and VisAO visible adaptive optics camera. The Magellan AO system is a 585-actuator low-emissivity high-throughput system scheduled for first light on the 6.5 meter Magellan Clay telescope in November 2012. Using a dichroic beamsplitter near the telescope focal plane, the AO system will be able to simultaneously perform visible (500-1000 nm) AO science with our VisAO camera and either 10 micron or 3-5 micron science using either the BLINC/MIRAC4 or CLIO cameras, respectively. The ASM, PWS, and VisAO camera have undergone final system tests in the solar test tower at the Arcetri Institute in Florence, Italy, reaching Strehls of 37% in i'-band with 400 modes and simulated turbulence of 14 cm ro at v-band. We present images and test results of the assembled VisAO system, which includes our prototype advanced Atmospheric Dispersion Corrector (ADC), prot...

  9. A Survey of High Level Frameworks in Block-Structured Adaptive Mesh Refinement Packages

    CERN Document Server

    Dubey, Anshu; Bell, John; Berzins, Martin; Brandt, Steve; Bryan, Greg; Colella, Phillip; Graves, Daniel; Lijewski, Michael; Löffler, Frank; O'Shea, Brian; Schnetter, Erik; Van Straalen, Brian; Weide, Klaus

    2016-01-01

    Over the last decade block-structured adaptive mesh refinement (SAMR) has found increasing use in large, publicly available codes and frameworks. SAMR frameworks have evolved along different paths. Some have stayed focused on specific domain areas, others have pursued a more general functionality, providing the building blocks for a larger variety of applications. In this survey paper we examine a representative set of SAMR packages and SAMR-based codes that have been in existence for half a decade or more, have a reasonably sized and active user base outside of their home institutions, and are publicly available. The set consists of a mix of SAMR packages and application codes that cover a broad range of scientific domains. We look at their high-level frameworks, and their approach to dealing with the advent of radical changes in hardware architecture. The codes included in this survey are BoxLib, Cactus, Chombo, Enzo, FLASH, and Uintah.

  10. Coronagraphic Imager with Adaptive Optics (CIAO) for the Subaru 8.2m Telescope

    Science.gov (United States)

    Tamura, M.; Suto, H.; Murakawa, K.; Hayashi, S.; Kaifu, N.; Itoh, Y.; Fukagawa, M.; Oasa, Y.; Naoi, T.

    2001-05-01

    We describe a near-infrared coronagraphic camera built for use with the Subaru 8.2m telescope and its adaptive optics system. This instrument, CIAO, aims to obtain high-resolution (0.06 arcsec at 2 micron) images of faint objects in close vicinity of bright objects at near-infrared wavelengths. The coronagraphic optics are all cooled. Occulting masks whose diameter ranges from 0.1 to 3 arcsec and several types of Lyot stops are selectable. Standard broad-band imaging and a number of narow-band imaging are possible with or without coronagraph, with two pixel scales of 22 mas/pixel and 11 mas/pixel. Low resolution coronagraphic grism spectroscopy is also available. CIAO utilize one ALLADIN II (1024x1024 InSb) scince-grade array detector manufactured by Raytheon, covering the wavelengths from 1 to 5 micron. CIAO will be very useful for studies of companion brown dwarfs and extra-solar planets, circumstelar disks around both young stelar obejcts and main-sequence stars, jets and outflows from both young stars and evolved stars, circumnuclear regions around AGNs, and host galaxies of QSOs. We also present preliminary results from the first commissioning run with adaptive optics at the Subaru telescope.

  11. Improved fixation quality provided by a Bessel beacon in an adaptive optics system.

    Science.gov (United States)

    Lambert, Andrew J; Daly, Elizabeth M; Dainty, Christopher J

    2013-07-01

    We investigate whether a structured probe beam that creates the beacon for use in a retinal imaging adaptive optics system can provide useful side effects. In particular we investigate whether a Bessel beam that is seen by the subject as a set of concentric rings has a dampening effect on fixation variations of the subject under observation. This calming effect would allow longer periods of observation, particularly for patients with abnormal fixation. An experimental adaptive optics system developed for retinal imaging is used to monitor the fluctuations in aberrations for artificial and human subjects. The probe beam is alternated between a traditional beacon and one provided by a Bessel beam created by SLM. Time-frequency analysis is used to indicate the differences in power and time variation during fixation depending on whether the Bessel beam or the traditional beacon is employed. Comparison is made with the response for an artificial eye to discount systemic variations. Significant evidence is accrued to indicate the reduced fluctuations in fixation when the Bessel beam is employed to create the beacon. © 2013 The Authors Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

  12. Adaptive high-frequency information fusion algorithm of radar and optical images

    Science.gov (United States)

    Wang, Yiding; Qin, Shuai

    2011-12-01

    An adaptive High-frequency Information Fusion Algorithm of Radar and Optical Images is proposed in this paper, in order to improve the resolution of the radar image and reserve more radar information. Firstly, Hough Transform is adopted in the process of low-resolution radar image and high-resolution optical image registration. The implicit linear information is extracted from two different heterogeneous images for better result. Then NSCT transform is used for decomposition and fusion. In different decomposition layers or in the same layer with different directions, fusion rules are adaptive for the high-frequency information of images. The ratio values of high frequency information entropy, variance, gradient and edge strength are calculated after NSCT decomposition. High frequency information entropy, variance, gradient or edge strength, which has the smallest ratio value, is selected as an optimal rule for regional fusion. High-frequency information of radar image could be better retained, at the same time the low-frequency information of optical image also could be remained. Experimental results showed that our approach performs better than those methods with single fusion rule.

  13. Early ComeOn+ Adaptive Optics Observation of GQ Lup and its Substellar Companion

    CERN Document Server

    Janson, M; Henning, T; Zinnecker, H; Janson, Markus; Brandner, Wolfgang; Henning, Thomas; Zinnecker, Hans

    2006-01-01

    An analysis of adaptive optics K-band imaging data of GQ Lup acquired in 1994 by the first generation adaptive optics system ComeOn+ at the ESO 3.6m optical telescope in La Silla is presented. The data reveal a likely candidate for the low-mass companion recently reported in the literature. An a posteriori detection in the 11 year old data would provide a useful astrometric data point for the very long period (~1000 yr) orbit of the GQ Lup system. However, the data is severely contaminated by speckle noise at the given projected separation, which decreases the confidence of the detection. Still, from the data we can conclude that GQ Lup B is not an unrelated background source, but instead a physical companion to GQ Lup A. We present here the reduction and analysis of the ComeOn+ images, as well as the results. We also discuss the nature of the companion based on data and models available in the scientific literature and examine claims made regarding the classification of the object as a planet.

  14. Model-based aberration correction in a closed-loop wavefront-sensor-less adaptive optics system

    NARCIS (Netherlands)

    Song, H.; Fraanje, R.; Schitter, G.; Kroese, H.; Vdovin, G.; Verhaegen, M.

    2010-01-01

    In many scientific and medical applications, such as laser systems and microscopes, wavefront-sensor-less (WFSless) adaptive optics (AO) systems are used to improve the laser beam quality or the image resolution by correcting the wavefront aberration in the optical path. The lack of direct wavefront

  15. DeepSurveyCam—A Deep Ocean Optical Mapping System

    OpenAIRE

    Tom Kwasnitschka; Kevin Köser; Jan Sticklus; Marcel Rothenbeck; Tim Weiß; Emanuel Wenzlaff; Timm Schoening; Lars Triebe; Anja Steinführer; Colin Devey; Jens Greinert

    2016-01-01

    Underwater photogrammetry and in particular systematic visual surveys of the deep sea are by far less developed than similar techniques on land or in space. The main challenges are the rough conditions with extremely high pressure, the accessibility of target areas (container and ship deployment of robust sensors, then diving for hours to the ocean floor), and the limitations of localization technologies (no GPS). The absence of natural light complicates energy budget considerations for deep ...

  16. Adaptive optics correction into single mode fiber for a low Earth orbiting space to ground optical communication link using the OPALS downlink.

    Science.gov (United States)

    Wright, Malcolm W; Morris, Jeffery F; Kovalik, Joseph M; Andrews, Kenneth S; Abrahamson, Matthew J; Biswas, Abhijit

    2015-12-28

    An adaptive optics (AO) testbed was integrated to the Optical PAyload for Lasercomm Science (OPALS) ground station telescope at the Optical Communications Telescope Laboratory (OCTL) as part of the free space laser communications experiment with the flight system on board the International Space Station (ISS). Atmospheric turbulence induced aberrations on the optical downlink were adaptively corrected during an overflight of the ISS so that the transmitted laser signal could be efficiently coupled into a single mode fiber continuously. A stable output Strehl ratio of around 0.6 was demonstrated along with the recovery of a 50 Mbps encoded high definition (HD) video transmission from the ISS at the output of the single mode fiber. This proof of concept demonstration validates multi-Gbps optical downlinks from fast slewing low-Earth orbiting (LEO) spacecraft to ground assets in a manner that potentially allows seamless space to ground connectivity for future high data-rates network.

  17. Classification of human retinal microaneurysms using adaptive optics scanning light ophthalmoscope fluorescein angiography.

    Science.gov (United States)

    Dubow, Michael; Pinhas, Alexander; Shah, Nishit; Cooper, Robert F; Gan, Alexander; Gentile, Ronald C; Hendrix, Vernon; Sulai, Yusufu N; Carroll, Joseph; Chui, Toco Y P; Walsh, Joseph B; Weitz, Rishard; Dubra, Alfredo; Rosen, Richard B

    2014-03-04

    Microaneurysms (MAs) are considered a hallmark of retinal vascular disease, yet what little is known about them is mostly based upon histology, not clinical observation. Here, we use the recently developed adaptive optics scanning light ophthalmoscope (AOSLO) fluorescein angiography (FA) to image human MAs in vivo and to expand on previously described MA morphologic classification schemes. Patients with vascular retinopathies (diabetic, hypertensive, and branch and central retinal vein occlusion) were imaged with reflectance AOSLO and AOSLO FA. Ninety-three MAs, from 14 eyes, were imaged and classified according to appearance into six morphologic groups: focal bulge, saccular, fusiform, mixed, pedunculated, and irregular. The MA perimeter, area, and feret maximum and minimum were correlated to morphology and retinal pathology. Select MAs were imaged longitudinally in two eyes. Adaptive optics scanning light ophthalmoscope fluorescein angiography imaging revealed microscopic features of MAs not appreciated on conventional images. Saccular MAs were most prevalent (47%). No association was found between the type of retinal pathology and MA morphology (P = 0.44). Pedunculated and irregular MAs were among the largest MAs with average areas of 4188 and 4116 μm(2), respectively. Focal hypofluorescent regions were noted in 30% of MAs and were more likely to be associated with larger MAs (3086 vs. 1448 μm(2), P = 0.0001). Retinal MAs can be classified in vivo into six different morphologic types, according to the geometry of their two-dimensional (2D) en face view. Adaptive optics scanning light ophthalmoscope fluorescein angiography imaging of MAs offers the possibility of studying microvascular change on a histologic scale, which may help our understanding of disease progression and treatment response.

  18. Adaptive Sensor Optimization and Cognitive Image Processing Using Autonomous Optical Neuroprocessors

    Energy Technology Data Exchange (ETDEWEB)

    CAMERON, STEWART M.

    2001-10-01

    Measurement and signal intelligence demands has created new requirements for information management and interoperability as they affect surveillance and situational awareness. Integration of on-board autonomous learning and adaptive control structures within a remote sensing platform architecture would substantially improve the utility of intelligence collection by facilitating real-time optimization of measurement parameters for variable field conditions. A problem faced by conventional digital implementations of intelligent systems is the conflict between a distributed parallel structure on a sequential serial interface functionally degrading bandwidth and response time. In contrast, optically designed networks exhibit the massive parallelism and interconnect density needed to perform complex cognitive functions within a dynamic asynchronous environment. Recently, all-optical self-organizing neural networks exhibiting emergent collective behavior which mimic perception, recognition, association, and contemplative learning have been realized using photorefractive holography in combination with sensory systems for feature maps, threshold decomposition, image enhancement, and nonlinear matched filters. Such hybrid information processors depart from the classical computational paradigm based on analytic rules-based algorithms and instead utilize unsupervised generalization and perceptron-like exploratory or improvisational behaviors to evolve toward optimized solutions. These systems are robust to instrumental systematics or corrupting noise and can enrich knowledge structures by allowing competition between multiple hypotheses. This property enables them to rapidly adapt or self-compensate for dynamic or imprecise conditions which would be unstable using conventional linear control models. By incorporating an intelligent optical neuroprocessor in the back plane of an imaging sensor, a broad class of high-level cognitive image analysis problems including geometric

  19. Rate-adaptive modulation and coding for optical fiber transmission systems

    Science.gov (United States)

    Gho, Gwang-Hyun; Kahn, Joseph M.

    2011-01-01

    Rate-adaptive optical transmission techniques adjust information bit rate based on transmission distance and other factors affecting signal quality. These techniques enable increased bit rates over shorter links, while enabling transmission over longer links when regeneration is not available. They are likely to become more important with increasing network traffic and a continuing evolution toward optically switched mesh networks, which make signal quality more variable. We propose a rate-adaptive scheme using variable-rate forward error correction (FEC) codes and variable constellations with a fixed symbol rate, quantifying how achievable bit rates vary with distance. The scheme uses serially concatenated Reed-Solomon codes and an inner repetition code to vary the code rate, combined with singlecarrier polarization-multiplexed M-ary quadrature amplitude modulation (PM-M-QAM) with variable M and digital coherent detection. A rate adaptation algorithm uses the signal-to-noise ratio (SNR) or the FEC decoder input bit-error ratio (BER) estimated by a receiver to determine the FEC code rate and constellation size that maximizes the information bit rate while satisfying a target FEC decoder output BER and an SNR margin, yielding a peak rate of 200 Gbit/s in a nominal 50-GHz channel bandwidth. We simulate single-channel transmission through a long-haul fiber system incorporating numerous optical switches, evaluating the impact of fiber nonlinearity and bandwidth narrowing. With zero SNR margin, we achieve bit rates of 200/100/50 Gbit/s over distances of 650/2000/3000 km. Compared to an ideal coding scheme, the proposed scheme exhibits a performance gap ranging from about 6.4 dB at 650 km to 7.5 dB at 5000 km.

  20. Wavefront sensorless adaptive optics fluorescence biomicroscope for in vivo retinal imaging in mice.

    Science.gov (United States)

    Wahl, Daniel J; Jian, Yifan; Bonora, Stefano; Zawadzki, Robert J; Sarunic, Marinko V

    2016-01-01

    Cellular-resolution in vivo fluorescence imaging is a valuable tool for longitudinal studies of retinal function in vision research. Wavefront sensorless adaptive optics (WSAO) is a developing technology that enables high-resolution imaging of the mouse retina. In place of the conventional method of using a Shack-Hartmann wavefront sensor to measure the aberrations directly, WSAO uses an image quality metric and a search algorithm to drive the shape of the adaptive element (i.e. deformable mirror). WSAO is a robust approach to AO and it is compatible with a compact, low-cost lens-based system. In this report, we demonstrated a hill-climbing algorithm for WSAO with a variable focus lens and deformable mirror for non-invasive in vivo imaging of EGFP (enhanced green fluorescent protein) labelled ganglion cells and microglia cells in the mouse retina.

  1. The field stabilization and adaptive optics mirrors for the European Extremely Large Telescope

    Science.gov (United States)

    Vernet, Elise; Jochum, Lieselotte; La Penna, Paolo; Hubin, Norbert; Muradore, Riccardo; Casalta, Joan Manel; Kjelberg, Ivar; Sinquin, Jean-Christophe; Locre, Frédéric; Morin, Pierre; Cousty, Raphaël; Lurçon, Jean-Marie; Roland, Jean-Jacques; Crepy, Bruno; Gabriel, Eric; Biasi, Roberto; Andrighettoni, Mario; Angerer, Gerald; Gallieni, Daniele; Mantegazza, Marco; Tintori, Matteo; Molinari, Emilio; Tresoldi, Daniela; Toso, Giorgio; Spanó, Paolo; Riva, Marco; Crimi, Giuseppe; Riccardi, Armando; Marque, Gilles; Carel, Jean-Louis; Ruch, Eric

    2008-07-01

    A 42 meters telescope does require adaptive optics to provide few milli arcseconds resolution images. In the current design of the E-ELT, M4 provides adaptive correction while M5 is the field stabilization mirror. Both mirrors have an essential role in the E-ELT telescope strategy since they do not only correct for atmospheric turbulence but have also to cancel part of telescope wind shaking and static aberrations. Both mirrors specifications have been defined to avoid requesting over constrained requirements in term of stroke, speed and guide stars magnitude. Technical specifications and technological issues are discussed in this article. Critical aspects and roadmap to assess the feasibility of such mirrors are outlined.

  2. woptic: optical conductivity with Wannier functions and adaptive k-mesh refinement

    CERN Document Server

    Assmann, E; Kuneš, J; Toschi, A; Blaha, P; Held, K

    2015-01-01

    We present an algorithm for the adaptive tetrahedral integration over the Brillouin zone of crystalline materials, and apply it to compute the optical conductivity, dc conductivity, and thermopower. For these quantities, whose contributions are often localized in small portions of the Brillouin zone, adaptive integration is especially relevant. Our implementation, the woptic package, is tied into the wien2wannier framework and allows including a many-body self energy, e.g. from dynamical mean-field theory (DMFT). Wannier functions and dipole matrix elements are computed with the DFT package Wien2k and Wannier90. For illustration, we show DFT results for fcc-Al and DMFT results for the correlated metal SrVO$_3$.

  3. AMA- and RWE- Based Adaptive Kalman Filter for Denoising Fiber Optic Gyroscope Drift Signal.

    Science.gov (United States)

    Yang, Gongliu; Liu, Yuanyuan; Li, Ming; Song, Shunguang

    2015-10-23

    An improved double-factor adaptive Kalman filter called AMA-RWE-DFAKF is proposed to denoise fiber optic gyroscope (FOG) drift signal in both static and dynamic conditions. The first factor is Kalman gain updated by random weighting estimation (RWE) of the covariance matrix of innovation sequence at any time to ensure the lowest noise level of output, but the inertia of KF response increases in dynamic condition. To decrease the inertia, the second factor is the covariance matrix of predicted state vector adjusted by RWE only when discontinuities are detected by adaptive moving average (AMA).The AMA-RWE-DFAKF is applied for denoising FOG static and dynamic signals, its performance is compared with conventional KF (CKF), RWE-based adaptive KF with gain correction (RWE-AKFG), AMA- and RWE- based dual mode adaptive KF (AMA-RWE-DMAKF). Results of Allan variance on static signal and root mean square error (RMSE) on dynamic signal show that this proposed algorithm outperforms all the considered methods in denoising FOG signal.

  4. Variable Delay With Directly-Modulated R-SOA and Optical Filters for Adaptive Antenna Radio-Fiber Access

    DEFF Research Database (Denmark)

    Prince, Kamau; Presi, Marco; Chiuchiarelli, Andrea

    2009-01-01

    on a directly-modulated reflective emiconductor amplifier (R-SOA) and exploits the interplay between transmission-line dispersion and tunable optical filtering to achieve flexible true time delay, with $2pi$ beam steering at the different antennas. The system was characterized, then successfully tested with two......We present an all-optical adaptive-antenna radio over fiber transport system that uses proven, commercially-available components to effectively deliver standard-compliant optical signaling to adaptive multiantenna arrays for current and emerging radio technology implementations. The system is based...

  5. Smart microscope: an adaptive optics learning system for aberration correction in multiphoton confocal microscopy.

    Science.gov (United States)

    Albert, O; Sherman, L; Mourou, G; Norris, T B; Vdovin, G

    2000-01-01

    Off-axis aberrations in a beam-scanning multiphoton confocal microscope are corrected with a deformable mirror. The optimal mirror shape for each pixel is determined by a genetic learning algorithm, in which the second-harmonic or two-photon fluorescence signal from a reference sample is maximized. The speed of the convergence is improved by use of a Zernike polynomial basis for the deformable mirror shape. This adaptive optical correction scheme is implemented in an all-reflective system by use of extremely short (10-fs) optical pulses, and it is shown that the scanning area of an f:1 off-axis parabola can be increased by nine times with this technique.

  6. Characterization and closed-loop performance of a liquid mirror adaptive optical system.

    Science.gov (United States)

    ten Have, Eric S; Vdovin, Gleb

    2012-04-20

    A deformable mirror based on the principle of total internal reflection of light from an electrostatically deformed liquid-air interface was realized and used to perform closed-loop adaptive optical (AO) correction on a collimated laser beam aberrated by a rotating phase disk. Equations describing the resonant and oscillatory behavior of the liquid system were obtained and applied to the system under consideration. Characterization of the mirror included open- and closed-loop frequency responses, determination of rise times, the damping times of the liquid, and the influence of liquid surface motion in the absence of external optical aberrations. The performance of the AO system was determined for static and dynamic aberrations for various sets of system parameters. The predictions of the general expressions were compared to the results of the experimental realization and were found to be in good agreement.

  7. Recovery Management in All Optical Networks Using Biologically-Inspired Complex Adaptive System

    Directory of Open Access Journals (Sweden)

    Inadyuti Dutt

    2013-01-01

    Full Text Available All-Optical Networks have the ability to display varied advantages like performance efficiency, throughput etc but their efficiency depends on their survivability as they are attack prone. These attacks can be categorised as active or passive because they try to access information within the network or alter the information in the network. The attack once detected has to be recovered by formulating back-up or alternative paths. The proposed heuristic uses biologically inspired Complex Adaptive System, inspired by Natural Immune System. The study shows that natural immune system exhibit unique behaviour of detecting foreign bodies in our body and removing them on their first occurrences. This phenomenon is being utilised in the proposed heuristic for recovery management in All-optical Network

  8. Combinational-deformable-mirror adaptive optics system for compensation of high-order modes of wavefront

    Institute of Scientific and Technical Information of China (English)

    Huafeng Yang; Guilin Liu; Changhui Rao; Yudong Zhang; Wenhan Jiang

    2007-01-01

    A new kind of adaptive optics (AO) system, in which several low spatial frequency deformable mirrors(DMs) with optical conjugation relationship are combined to correct high-order aberrations, is proposed.The phase compensation principle and the control method of the combinational AO system are introduced.The numerical simulations for the AO system with two 60-element DMs are presented. The results indicate that the combinational DM in the AO system can correct different aberrations effectively as one single DM with more actuators, and there is no change of control method. This technique can be applied to a large telescope AO system to improve the spatial compensation capability for wavefront by using current DM.

  9. Stochastic parallel gradient descent based adaptive optics used for high contrast imaging coronagraph

    CERN Document Server

    Dong, Bing; Zhang, Xi

    2011-01-01

    An adaptive optics (AO) system based on stochastic parallel gradient descent (SPGD) algorithm is proposed to reduce the speckle noises in the optical system of stellar coronagraph in order to further improve the contrast. The principle of SPGD algorithm is described briefly and a metric suitable for point source imaging optimization is given. The feasibility and good performance of SPGD algorithm is demonstrated by experimental system featured with a 140-actuators deformable mirror (DM) and a Hartmann- Shark wavefront sensor. Then the SPGD based AO is applied to a liquid crystal array (LCA) based coronagraph. The LCA can modulate the incoming light to generate a pupil apodization mask in any pattern. A circular stepped pattern is used in our preliminary experiment and the image contrast shows improvement from 10^-3 to 10^-4.5 at angular distance of 2{\\lambda}/D after corrected by SPGD based AO.

  10. The IRCAL Polarimeter: Design, Calibration, and Data Reduction for an Adaptive Optics Imaging Polarimeter

    CERN Document Server

    Perrin, Marshall D; Lloyd, James P

    2008-01-01

    We have upgraded IRCAL, the near-infrared science camera of the Lick Observatory adaptive optics system, to add a dual-channel imaging polarimetry mode. This mode uses an optically contacted YLF (LiYF_4) Wollaston prism to provide simultaneous images in perpendicular linear polarizations, providing high resolution, high dynamic range polarimetry in the near infrared. We describe the design and construction of the polarimeter, discuss in detail the data reduction algorithms adopted, and evaluate the instrument's on-the-sky performance. The IRCAL polarimeter is capable of reducing the stellar PSF halo by about two orders of magnitude, thereby increasing contrast for studies of faint circumstellar dust-scattered light. We discuss the various factors that limit the achieved contrast, and present lessons applicable to future high contrast imaging polarimeters.

  11. Fiber Bragg grating dynamic strain sensor using an adaptive reflective semiconductor optical amplifier source.

    Science.gov (United States)

    Wei, Heming; Tao, Chuanyi; Zhu, Yinian; Krishnaswamy, Sridhar

    2016-04-01

    In this paper, a reflective semiconductor optical amplifier (RSOA) is configured to demodulate dynamic spectral shifts of a fiber Bragg grating (FBG) dynamic strain sensor. The FBG sensor and the RSOA source form an adaptive fiber cavity laser. As the reflective spectrum of the FBG sensor changes due to dynamic strains, the wavelength of the laser output shifts accordingly, which is subsequently converted into a corresponding phase shift and demodulated by an unbalanced Michelson interferometer. Due to the short transition time of the RSOA, the RSOA-FBG cavity can respond to dynamic strains at high frequencies extending to megahertz. A demodulator using a PID controller is used to compensate for low-frequency drifts induced by temperature and large quasi-static strains. As the sensitivity of the demodulator is a function of the optical path difference and the FBG spectral width, optimal parameters to obtain high sensitivity are presented. Multiplexing to demodulate multiple FBG sensors is also discussed.

  12. Adaptive Optics Imaging of Lyman Break Galaxies as Progenitors of Spheroids in the Local Universe

    CERN Document Server

    Akiyama, M; Kobayashi, N; Ohta, K; Iwata, I

    2007-01-01

    In order to reveal the stellar mass distribution of z~3 galaxies, we are conducting deep imaging observations of U-dropout Lyman Break Galaxies (LBGs) with Adaptive Optics (AO) systems in K-band, which corresponds to rest-frame V-band of z~3 galaxies. The results of the Subaru intensive-program observations with AO36/NGS/IRCS indicate that 1) the K-band peaks of some of the LBGs brighter than K=22.0 mag show significant offset from those in the optical images, 2) the z~3 Mv* LBGs and serendipitously observed Distant Red Galaxies (DRGs) have flat profiles similar to disk galaxies in the local universe (i.e., Sersic with n2 systems among the luminous z~3 LBGs and DRGs, and their strong spatial clustering, we infer that the dense n2 spheroids of nearby galaxies through relaxations due to major merger events.

  13. Ferrofluid Based Deformable Mirrors - a New Approach to Adaptive Optics Using Liquid Mirrors

    CERN Document Server

    Laird, P; Berube, V; Borra, E F; Ritcey, A; Rioux, M; Robitaille, N; Thibault, S; Yockell-Lelievre, H

    2002-01-01

    The trend towards ever larger telescopes and more advanced adaptive optics systems is driving the need for deformable mirrors with a large number of low cost actuators. Liquid mirrors have long been recognized a potential low cost alternative to conventional solid mirrors. By using a water or oil based ferrofluid we are able to benefit from a stronger magnetic response than is found in magnetic liquid metal amalgams and avoid the difficulty of passing a uniform current through a liquid. Depositing a thin silver colloid known as a metal liquid-like film (MELLF) on the ferrofluid surface solves the problem of low reflectivity of pure ferrofluids. This combination provides a liquid optical surface that can be precisely shaped in a magnetic field. We present experimental results obtained with a prototype deformable liquid mirror based on this combination.

  14. Numerical control matrix rotation for the LINC-NIRVANA multiconjugate adaptive optics system

    Science.gov (United States)

    Arcidiacono, Carmelo; Bertram, Thomas; Ragazzoni, Roberto; Farinato, Jacopo; Esposito, Simone; Riccardi, Armando; Pinna, Enrico; Puglisi, Alfio; Fini, Luca; Xompero, Marco; Busoni, Lorenzo; Quiros-Pacheco, Fernando; Briguglio, Runa

    2010-07-01

    LINC-NIRVANA will realize the interferometric imaging focal station of the Large Binocular Telescope. A double Layer Oriented multi-conjugate adaptive optics system assists the two arms of the interferometer, supplying high order wave-front correction. In order to counterbalance the field rotation, mechanical derotation for the two ground wave-front sensors, and optical derotators for the mid-high layers sensors fix the positions of the focal planes with respect to the pyramids aboard the wave-front sensors. The derotation introduces pupil images rotation on the wavefront sensors: the projection of the deformable mirrors on the sensor consequently change. The proper adjustment of the control matrix will be applied in real-time through numerical computation of the new matrix. In this paper we investigate the temporal and computational aspects related to the pupils rotation, explicitly computing the wave-front errors that may be generated.

  15. Active eye-tracking for an adaptive optics scanning laser ophthalmoscope

    Science.gov (United States)

    Sheehy, Christy K.; Tiruveedhula, Pavan; Sabesan, Ramkumar; Roorda, Austin

    2015-01-01

    We demonstrate a system that combines a tracking scanning laser ophthalmoscope (TSLO) and an adaptive optics scanning laser ophthalmoscope (AOSLO) system resulting in both optical (hardware) and digital (software) eye-tracking capabilities. The hybrid system employs the TSLO for active eye-tracking at a rate up to 960 Hz for real-time stabilization of the AOSLO system. AOSLO videos with active eye-tracking signals showed, at most, an amplitude of motion of 0.20 arcminutes for horizontal motion and 0.14 arcminutes for vertical motion. Subsequent real-time digital stabilization limited residual motion to an average of only 0.06 arcminutes (a 95% reduction). By correcting for high amplitude, low frequency drifts of the eye, the active TSLO eye-tracking system enabled the AOSLO system to capture high-resolution retinal images over a larger range of motion than previously possible with just the AOSLO imaging system alone. PMID:26203370

  16. Performance of wavefront-sensorless adaptive optics using modal and zonal correction

    Science.gov (United States)

    Anzuola, Esdras; Segel, Max; Gladysz, Szymon; Stein, Karin

    2016-10-01

    Unconventional wavefront sensing strategies are being developed to provide alternatives for measuring the wavefront deformation of a laser beam propagating through strong turbulence and/or along a horizontal-path. In this paper we present results from two "wavefront-sensorless" approaches: stochastic parallel gradient descent (SPGD) and its modal version (M-SPGD). We compare the performance of both algorithms through experimental measurements under emulated dynamic atmospheric turbulence by using the coupling efficiency in a single mode fiber as performance metric. We estimate probability density function of coupling efficiency for free-space optical links using adaptive optics (AO) as a function of key parameters such us turbulence strength and AO loop rate. We demonstrate faster convergence rate of the M-SPGD algorithm as compared to the traditional SPGD, although classic SPGD achieves higher correction. Additionally, we constrain the main temporal requirements of an AO system using wavefront-sensorless architectures.

  17. Active eye-tracking for an adaptive optics scanning laser ophthalmoscope.

    Science.gov (United States)

    Sheehy, Christy K; Tiruveedhula, Pavan; Sabesan, Ramkumar; Roorda, Austin

    2015-07-01

    We demonstrate a system that combines a tracking scanning laser ophthalmoscope (TSLO) and an adaptive optics scanning laser ophthalmoscope (AOSLO) system resulting in both optical (hardware) and digital (software) eye-tracking capabilities. The hybrid system employs the TSLO for active eye-tracking at a rate up to 960 Hz for real-time stabilization of the AOSLO system. AOSLO videos with active eye-tracking signals showed, at most, an amplitude of motion of 0.20 arcminutes for horizontal motion and 0.14 arcminutes for vertical motion. Subsequent real-time digital stabilization limited residual motion to an average of only 0.06 arcminutes (a 95% reduction). By correcting for high amplitude, low frequency drifts of the eye, the active TSLO eye-tracking system enabled the AOSLO system to capture high-resolution retinal images over a larger range of motion than previously possible with just the AOSLO imaging system alone.

  18. Centroid gain compensation in Shack-Hartmann adaptive optics systems with natural or laser guide star

    Science.gov (United States)

    Veran; Herriot

    2000-08-01

    In an adaptive optics system with an undersampled Shack-Hartmann wave-front sensor (WFS), variations in seeing, laser guide star quality, and sodium layer thickness and range distance all combine to vary WFS centroid gain across the pupil during an exposure. While using the minimum of 4 pixels per WFS subaperture improves frame rate and read noise, the WFS centroid gain uncertainty may introduce static aberrations and degrade servo loop phase margin. We present a novel method to estimate and compensate WFS gains of each subaperture individually in real time for both natural and laser guide stars.

  19. Bi-photon propagation control with optimized wavefront by means of Adaptive Optics

    CERN Document Server

    Minozzi, M; Sergienko, A V; Vallone, G; Villoresi, P

    2012-01-01

    We present an efficient method to control the spatial modes of entangled photons produced through SPDC process. Bi-photon beam propagation is controlled by a deformable mirror, that shapes a 404nm CW diode laser pump interacting with a nonlinear BBO type-I crystal. Thanks to adaptive optical system, the propagation of 808nm SPDC light produced is optimized over a distance of 2m. The whole system optimization is carried out by a feedback between deformable mirror action and entangled photon coincidence counts. We also demonstrated the improvement of the two-photon coupling into single mode fibers.

  20. Performance of centroiding algorithms at low light level conditions in adaptive optics

    CERN Document Server

    Vyas, Akondi; Prasad, B Raghavendra; 10.1109/ARTCom.2009.30

    2010-01-01

    The performance metrics of different centroiding algorithms at low light level conditions were optimized in the case of a Shack Hartmann Sensor (SHS) for efficient performance of the adaptive optics system. For short exposures and low photon flux, the Hartmann spot does not have a Gaussian shape due to the photon noise which follows Poissonian statistics. The centroiding estimation error was calculated at different photon levels in the case of changing spot size and shift in the spot using Monte Carlo simulations. This analysis also proves to be helpful in optimizing the SHS specifications at low light levels.

  1. Recent Science and Engineering Results with the Laser Guidestar Adaptive Optics System at Lick Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Gavel, D T; Gates, E; Max, C; Olivier, S; Bauman, B; Pennington, D; Macintosh, B; Patience, J; Brown, C; Danforth, P; Hurd, R; Severson, S; Lloyd, J

    2002-10-17

    The Lick Observatory laser guide star adaptive optics system has undergone continual improvement and testing as it is being integrated as a facility science instrument on the Shane 3 meter telescope. Both Natural Guide Star (NGS) and Laser Guide Star (LGS) modes are now used in science observing programs. We report on system performance results as derived from data taken on both science and engineering nights and also describe the newly developed on-line techniques for seeing and system performance characterization. We also describe the future enhancements to the Lick system that will enable additional science goals such as long-exposure spectroscopy.

  2. High-resolution adaptive optics scanning laser ophthalmoscope with multiple deformable mirrors

    Science.gov (United States)

    Chen, Diana C.; Olivier, Scot S.; Jones; Steven M.

    2010-02-23

    An adaptive optics scanning laser ophthalmoscopes is introduced to produce non-invasive views of the human retina. The use of dual deformable mirrors improved the dynamic range for correction of the wavefront aberrations compared with the use of the MEMS mirror alone, and improved the quality of the wavefront correction compared with the use of the bimorph mirror alone. The large-stroke bimorph deformable mirror improved the capability for axial sectioning with the confocal imaging system by providing an easier way to move the focus axially through different layers of the retina.

  3. Performance Impacts for Actuator Misalignments and Failures in Large- Aperture Adaptive-Optic Telescopes

    Science.gov (United States)

    1993-12-01

    reconstitution operations after the Loma Prieta earthquake of 1989. Along with his wife, Mary Ann, and daughters, Kelly Ann and Melissa, he entered the...Block Diagram of Adaptive Optics Simulation ...................................................... 3-3 4-1 Misalignment Effects on Radial-Averaged OTF...r0 = 13, ph = 2x10 6 , vT = 0). 4-10 4-2 Misalignment Effects on Change in OTF (r0 = 13, ph = 2xl0 6 , vt = 0) ............ 4-10 4-3 Misalignment

  4. Progress with multi-conjugate adaptive optics at the Big Bear Solar Observatory

    Science.gov (United States)

    Schmidt, Dirk; Gorceix, Nicolas; Marino, Jose; Zhang, Xianyu; Berkefeld, Thomas; Rimmele, Thomas R.; Goode, Philip R.

    2016-05-01

    The MCAO system at BBSO is the pathfinder system for a future system at the 4-meter DKIST. It deploys three DMs, one in the pupil and two in higher altitudes. The design allows to move the latter independently to adapt to the turbulence profile within about 2-9 km.The optical path has been improved in 2015, and has shown satisfying solar images. The MCAO loop was able to improve the wavefront error across the field slightly compared to classical AO.We will report on the latest improvements, on-Sun results and motivate the design of the system.

  5. Precise Astrometry of Visual Binaries with Adaptive Optics. A Way for Finding Exoplanets?

    CERN Document Server

    Hełminiak, Krzysztof

    2008-01-01

    We present the results of our study of astrometric stability of 200-in Hale (Mt. Palomar) and 10-m Keck II (Mauna Kea) telescopes, both with Adaptive Optics (AO) facilities. A group of nearby visual binaries and multiples was observed in near infrared, relative separations and position angles measured. We have also checked the influence of some systematic effects (e.g. atmospherical refraction, varying plate scale factor) on result and precision of astrometric measurements. We conclude that in visual binaries astrometrical observations it is possible to achieve much better precision than 1 miliarcsecond, which in many cases allows detection of the astrometrical signal produced by planetary-mass object.

  6. High resolution mosaic image of capillaries in human retina by adaptive optics

    Institute of Scientific and Technical Information of China (English)

    Ning Ling; Yudong Zhang; Xuejun Rao; Cheng Wang; Yiyun Hu; Wenhan Jiang

    2005-01-01

    Adaptive optics (AO) has been proved as a powerful means for high resolution imaging of human retina.Because of the pixel number of charge-coupled device (CCD) camera, the field of view is limited to 1°.In order to have image of capillaries around vivo human fovea, we use mosaic method to obtain high resolution image in area of 6°× 6°. Detailed structures of capillaries around fovea with resolution of 2.3μm are clearly shown. Comparison shows that this method has a much higher resolution than current clinic retina imaging methods.

  7. Frida: the first instrument for the adaptive optics system of GTC

    OpenAIRE

    López, J. A.; V. Bringas; S. Cuevas; J. J. Díaz; Eikenberry, S. S.; Espejo, C.; Flores, R.; F. J. Fuentes; Gallego, J.; Garzón, F.; Hammersley, P.; Pelló, R.; Prieto, A.; Sánchez, B.; Watson, A.

    2007-01-01

    FRIDA (inFRrared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) se está diseñando como un instrumento con óptica limitada por difracción con capacidades de imagen de banda ancha y angosta y espectroscopia integral de campo para operar en el intervalo de longitudes de onda de 0.9 2.5 um. FRIDA es un proyecto de colaboración entre los socios principales de GTC; a saber, España, México y Florida. Las principales características de diseño de FRID...

  8. Configuration optimization of laser guide stars and wavefront correctors for multi-conjugation adaptive optics

    Science.gov (United States)

    Xuan, Li; He, Bin; Hu, Li-Fa; Li, Da-Yu; Xu, Huan-Yu; Zhang, Xing-Yun; Wang, Shao-Xin; Wang, Yu-Kun; Yang, Cheng-Liang; Cao, Zhao-Liang; Mu, Quan-Quan; Lu, Xing-Hai

    2016-09-01

    Multi-conjugation adaptive optics (MCAOs) have been investigated and used in the large aperture optical telescopes for high-resolution imaging with large field of view (FOV). The atmospheric tomographic phase reconstruction and projection of three-dimensional turbulence volume onto wavefront correctors, such as deformable mirrors (DMs) or liquid crystal wavefront correctors (LCWCs), is a very important step in the data processing of an MCAO’s controller. In this paper, a method according to the wavefront reconstruction performance of MCAO is presented to evaluate the optimized configuration of multi laser guide stars (LGSs) and the reasonable conjugation heights of LCWCs. Analytical formulations are derived for the different configurations and are used to generate optimized parameters for MCAO. Several examples are given to demonstrate our LGSs configuration optimization method. Compared with traditional methods, our method has minimum wavefront tomographic error, which will be helpful to get higher imaging resolution at large FOV in MCAO. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174274, 11174279, 61205021, 11204299, 61475152, and 61405194) and the State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences.

  9. Delay-aware adaptive sleep mechanism for green wireless-optical broadband access networks

    Science.gov (United States)

    Wang, Ruyan; Liang, Alei; Wu, Dapeng; Wu, Dalei

    2017-07-01

    Wireless-Optical Broadband Access Network (WOBAN) is capacity-high, reliable, flexible, and ubiquitous, as it takes full advantage of the merits from both optical communication and wireless communication technologies. Similar to other access networks, the high energy consumption poses a great challenge for building up WOBANs. To shot this problem, we can make some load-light Optical Network Units (ONUs) sleep to reduce the energy consumption. Such operation, however, causes the increased packet delay. Jointly considering the energy consumption and transmission delay, we propose a delay-aware adaptive sleep mechanism. Specifically, we develop a new analytical method to evaluate the transmission delay and queuing delay over the optical part, instead of adopting M/M/1 queuing model. Meanwhile, we also analyze the access delay and queuing delay of the wireless part. Based on such developed delay models, we mathematically derive ONU's optimal sleep time. In addition, we provide numerous simulation results to show the effectiveness of the proposed mechanism.

  10. Optical local area network emulations over Ethernet passive optical networks: A survey

    Institute of Scientific and Technical Information of China (English)

    PENG YunFeng; KUANG YuJun; LONG KePing

    2008-01-01

    As a promising solution to efficiently achieving fiber to the home (FTTH), Ethernet passive optical network (EPON) is currently improved to provide intercommunica-tion among customers, together with normal traffic delivery, via optical local area network emulation. It is a new research direction and expected to enhance the normal EPON performances. The purpose of this article is to review the state-of-the-art solutions to emulating optical local area networks (OLANs) over EPON. We discuss the major problems involved, e.g., network architecture, control mecha-nisms, and other potential enhancements. We also outline areas for future re-searches.

  11. EDiFiSE full-FPGA adaptive optics: first laboratory results using the IACAT optical ground support equipment

    Science.gov (United States)

    Chulani, Haresh M.; Martín, Yolanda; Fuensalida, Jesús J.; Rodríguez-Ramos, Luis F.; Echeandía, Carlos; Puga, Marta; Alonso, Angel

    2016-07-01

    This paper reviews the EDiFiSE (Equalized and Diffraction-limited Field Spectrograph Experiment) full-FPGA (Field Programmable Gate Array) adaptive optics (AO) system and presents its first laboratory results. EDiFiSE is a prototype equalized integral field unit (EIFU) spectrograph for the observation of high-contrast systems in the Willian Herschel Telescope (WHT). Its AO system comprises two independent parallel full-FPGA control loops, one for tip-tilt and one for higher order aberrations. Xilinx's Virtex-4 and Virtex-5 FPGA's fixed point arithmetic and their interfacing with the rest of the AO components and the user have been adequately dealt with, and a very deterministic system with a negligible computational delay has been obtained. The AO system has been recently integrated in laboratory and verified using the IACAT (IAC Atmosphere and Telescope) optical ground support equipment. Closed loop correction bandwidths of 65 Hz for the tip-tilt and 25 Hz for higher order aberrations are obtained. The system has been tested in the visible range for the WHT with a 9 x 9 subpupil configuration, low star magnitude, wind speeds up to 10 m/s and Fried parameter down to 18 cm, and a resolution below the EIFU's fiber section has been obtained.

  12. Multi-modal adaptive optics system including fundus photography and optical coherence tomography for the clinical setting.

    Science.gov (United States)

    Salas, Matthias; Drexler, Wolfgang; Levecq, Xavier; Lamory, Barbara; Ritter, Markus; Prager, Sonja; Hafner, Julia; Schmidt-Erfurth, Ursula; Pircher, Michael

    2016-05-01

    We present a new compact multi-modal imaging prototype that combines an adaptive optics (AO) fundus camera with AO-optical coherence tomography (OCT) in a single instrument. The prototype allows acquiring AO fundus images with a field of view of 4°x4° and with a frame rate of 10fps. The exposure time of a single image is 10 ms. The short exposure time results in nearly motion artifact-free high resolution images of the retina. The AO-OCT mode allows acquiring volumetric data of the retina at 200kHz A-scan rate with a transverse resolution of ~4 µm and an axial resolution of ~5 µm. OCT imaging is acquired within a field of view of 2°x2° located at the central part of the AO fundus image. Recording of OCT volume data takes 0.8 seconds. The performance of the new system is tested in healthy volunteers and patients with retinal diseases.

  13. A systematic approach to cross-cultural adaptation of survey tools.

    Directory of Open Access Journals (Sweden)

    Costa FA

    2007-09-01

    Full Text Available Background: Involving patients in health care is increasingly acknowledged as the best way to empower patients to manage their illness. Whilst the involvement of patients is laudable and widely recognised, how much they want to be involved needs to be ascertained. Research has shown that inappropriate provision of information to patients can increase their anxieties towards illness and alter perceptions of medicines’ usefulness, consequently impacting on medicines’ taking behaviour. Tools have been validated in the UK to identify information desires, perceived usefulness of medicines and anxiety felt about illness. There is a need to adapt validated tools for use in other settings and countries. This paper is the first of a series describing the processes involved in the adaptation and validation of these. Aim: to review and adapt the processes established to translate and back translate scales and tools in practice. Methods: The survey tool was translated and back-translated according to published guidelines, subsequently tested in a sample of medical patients and further refined by seeking health care professionals’ perceptions and input from lay people. Results: Data demonstrates the importance of including various perspectives in this process, through which sequential modifications were made to the original scales. Issues relating to religious beliefs, educational and health literacy differences between countries highlight the relevance of taking cultural values into account. Some led to significant modifications, discussed in this first paper, and tested for validity and reliability in a second paper.

  14. Optically selected BL Lacertae candidates from the Sloan Digital Sky Survey Data Release Seven

    NARCIS (Netherlands)

    R.M. Plotkin; S.F. Anderson; W.N. Brandt; A.M. Diamond-Stanic; X. Fan; P.B. Hall; A.E. Kimball; M.W. Richmond; D.P. Schneider; O. Shemmer; W. Voges; D.G. York; N.A. Bahcall; S. Snedden; D. Bizyaev; H. Brewington; V. Malanushenko; E. Malanushenko; D. Oravetz; K. Pan; A. Simmons

    2010-01-01

    We present a sample of 723 optically selected BL Lac candidates from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) spectroscopic database encompassing 8250 deg(2) of sky; our sample constitutes one of the largest uniform BL Lac samples yet derived. Each BL Lac candidate has a high-quality S

  15. Seoul National University Bright Quasar Survey in Optical (SNUQSO) I: First Phase Observations and Results

    CERN Document Server

    Lee, Induk; Kim, Minjin; Kang, Eugene; Shim, Hyunjin; Richards, Gordon T; Edge, Alastair C; Lee, Myung Gyoon; Park, Changbom; Park, Myeong-Gu

    2008-01-01

    We present results from the first phase of the Seoul National University Bright Quasar Survey in Optical (SNUQSO) as well as its basic observational setup. Previous and current large-area surveys have been successful in identifying many quasars, but they could have missed bright quasars due to their survey design. In order to help complete the census of bright quasars, we have performed spectroscopic observations of new bright quasar candidates selected from various methods based on optical colors, near-infrared colors, radio, and X-ray data. In 2005/2006, we observed 55 bright quasar candidates using the Bohyunsan Optical Echelle Spectrograph (BOES) on the 1.8 m telescope at the Bohyunsan Optical Astronomy Observatory in Korea. We identify 14 quasars/Seyferts from our observation, including an optically bright quasar with i=14.98 mag at z=0.092 (SDSS J003236.59-091026.2). Non-quasar/Seyfert objects are found to be mostly stars, among which there are five M-type stars and one cataclysmic variable. Our result ...

  16. ESO Imaging Survey. Deep Public Survey Multi-Color Optical Data for the Chandra Deep Field South

    CERN Document Server

    Arnouts, S; Benoist, C; Groenewegen, M A T; Costa, L; Schirmer, M; Mignani, R P; Slijkhuis, R; Hatziminaoglou, E; Hook, R; Madejsky, R; Rité, C; Wicenec, A

    2001-01-01

    (short) This paper presents multi-passband optical data obtained from observations of the Chandra Deep Field South (CDF-S), located at alpha ~ 3h 32m, delta ~ -27d 48m. The observations were conducted at the ESO/MPG 2.2m telescope at La Silla using the 8kx8k Wide-Field Imager (WFI). This data set, taken over a period of one year, represents the first field to be completed by the ongoing Deep Public Survey (DPS) being carried out by the ESO Imaging Survey (EIS) project. This paper describes the optical observations, the techniques employed for un-supervised pipeline processing and the general characteristics of the final data set. The paper includes data taken in six different filters U'UBVRI. The data cover an area of about 0.25 square degrees reaching 5 sigma limiting magnitudes of U'_AB=26.0, U_AB=25.7, B_AB=26.4$, V_AB=25.4, R_AB=25.5 and I_AB= 24.7 mag, as measured within a 2xFWHM aperture. The optical data covers the area of ~ 0.1 square degrees for which moderately deep observations in two near-infrared...

  17. HI and cosmological constraints from intensity mapping, optical, and CMB surveys

    CERN Document Server

    Pourtsidou, Alkistis; Crittenden, Robert

    2016-01-01

    We forecast constraints on neutral hydrogen (HI) and cosmological parameters using near-term intensity mapping surveys with instruments such as BINGO, MeerKAT, and the SKA, and Stage III and IV optical galaxy surveys. If foregrounds and systematic effects can be controlled - a problem which becomes much easier in cross-correlation - these surveys will provide exquisite measurements of the HI density and bias, as well as measurements of the growth of structure, the angular diameter distance, and the Hubble rate, over a wide range of redshift. We also investigate the possibility of detecting the late time ISW effect using the Planck satellite and forthcoming intensity mapping surveys, finding that a large sky survey with Phase 1 of the SKA can achieve a near optimal detection.

  18. Adaptive automatic data analysis in full-field fringe-pattern-based optical metrology

    Science.gov (United States)

    Trusiak, Maciej; Patorski, Krzysztof; Sluzewski, Lukasz; Pokorski, Krzysztof; Sunderland, Zofia

    2016-12-01

    Fringe pattern processing and analysis is an important task of full-field optical measurement techniques like interferometry, digital holography, structural illumination and moiré. In this contribution we present several adaptive automatic data analysis solutions based on the notion of Hilbert-Huang transform for measurand retrieval via fringe pattern phase and amplitude demodulation. The Hilbert-Huang transform consists of 2D empirical mode decomposition algorithm and Hilbert spiral transform analysis. Empirical mode decomposition adaptively dissects a meaningful number of same-scale subimages from the analyzed pattern - it is a data-driven method. Appropriately managing this set of unique subimages results in a very powerful fringe pre-filtering tool. Phase/amplitude demodulation is performed using Hilbert spiral transform aided by the local fringe orientation estimator. We describe several optical measurement techniques for technical and biological objects characterization basing on the especially tailored Hilbert-Huang algorithm modifications for fringe pattern denoising, detrending and amplitude/phase demodulation.

  19. MAD Adaptive Optics Imaging of High-luminosity Quasars: A Pilot Project

    Science.gov (United States)

    Liuzzo, E.; Falomo, R.; Paiano, S.; Treves, A.; Uslenghi, M.; Arcidiacono, C.; Baruffolo, A.; Diolaiti, E.; Farinato, J.; Lombini, M.; Moretti, A.; Ragazzoni, R.; Brast, R.; Donaldson, R.; Kolb, J.; Marchetti, E.; Tordo, S.

    2016-08-01

    We present near-IR images of five luminous quasars at z ˜ 2 and one at z ˜ 4 obtained with an experimental adaptive optics (AO) instrument at the European Southern Observatory Very Large Telescope. The observations are part of a program aimed at demonstrating the capabilities of multi-conjugated adaptive optics imaging combined with the use of natural guide stars for high spatial resolution studies on large telescopes. The observations were mostly obtained under poor seeing conditions but in two cases. In spite of these nonoptimal conditions, the resulting images of point sources have cores of FWHM ˜ 0.2 arcsec. We are able to characterize the host galaxy properties for two sources and set stringent upper limits to the galaxy luminosity for the others. We also report on the expected capabilities for investigating the host galaxies of distant quasars with AO systems coupled with future Extremely Large Telescopes. Detailed simulations show that it will be possible to characterize compact (2-3 kpc) quasar host galaxies for quasi-stellar objects at z = 2 with nucleus K-magnitude spanning from 15 to 20 (corresponding to absolute magnitude -31 to -26) and host galaxies that are 4 mag fainter than their nuclei.

  20. Astrometric performance of the Gemini multi-conjugate adaptive optics system in crowded fields

    CERN Document Server

    Neichel, Benoit; Rigaut, Francois; Ammons, S Mark; Carrasco, Eleazar R; Lassalle, Emmanuel

    2014-01-01

    The Gemini Multi-conjugate adaptive optics System (GeMS) is a facility instrument for the Gemini-South telescope. It delivers uniform, near-diffraction-limited image quality at near-infrared wavelengths over a 2 arcminute field of view. Together with the Gemini South Adaptive Optics Imager (GSAOI), a near-infrared wide field camera, GeMS/GSAOI's combination of high spatial resolution and a large field of view will make it a premier facility for precision astrometry. Potential astrometric science cases cover a broad range of topics including exo-planets, star formation, stellar evolution, star clusters, nearby galaxies, black holes and neutron stars, and the Galactic center. In this paper, we assess the astrometric performance and limitations of GeMS/GSAOI. In particular, we analyze deep, mono-epoch images, multi-epoch data and distortion calibration. We find that for single-epoch, un-dithered data, an astrometric error below 0.2 mas can be achieved for exposure times exceeding one minute, provided enough star...