WorldWideScience

Sample records for ground-based deformable mirror

  1. Deformable mirrors : Design fundamentals for force actuation of continuous facesheets

    NARCIS (Netherlands)

    Ravensbergen, S.K.; Hamelinck, R.F.H.M.; Rosielle, P.C.J.N.; Steinbuch, M.

    2009-01-01

    Adaptive Optics is established as essential technology in current and future ground based (extremely) large telescopes to compensate for atmospheric turbulence. Deformable mirrors for astronomic purposes have a high number of actuators (> 10k), a relatively large stroke (> 10µm) on a small spacing (

  2. Deformable mirror with thermal actuators.

    Science.gov (United States)

    Vdovin, Gleb; Loktev, Mikhail

    2002-05-01

    Low-cost adaptive optics is applied in lasers, scientific instrumentation, ultrafast sciences, and ophthalmology. These applications demand that the deformable mirrors used be simple, inexpensive, reliable, and efficient. We report a novel type of ultralow-cost deformable mirror with thermal actuators. The device has a response time of ~5 s , an actuator stroke of ~6mum , and temporal stability of ~lambda/10 rms in the visible range and can be used for correction of rather large aberrations with slow-changing amplitude.

  3. Development of a miniaturized deformable mirror controller

    Science.gov (United States)

    Bendek, Eduardo; Lynch, Dana; Pluzhnik, Eugene; Belikov, Ruslan; Klamm, Benjamin; Hyde, Elizabeth; Mumm, Katherine

    2016-07-01

    High-Performance Adaptive Optics systems are rapidly spreading as useful applications in the fields of astronomy, ophthalmology, and telecommunications. This technology is critical to enable coronagraphic direct imaging of exoplanets utilized in ground-based telescopes and future space missions such as WFIRST, EXO-C, HabEx, and LUVOIR. We have developed a miniaturized Deformable Mirror controller to enable active optics on small space imaging mission. The system is based on the Boston Micromachines Corporation Kilo-DM, which is one of the most widespread DMs on the market. The system has three main components: The Deformable Mirror, the Driving Electronics, and the Mechanical and Heat management. The system is designed to be extremely compact and have lowpower consumption to enable its use not only on exoplanet missions, but also in a wide-range of applications that require precision optical systems, such as direct line-of-sight laser communications, and guidance systems. The controller is capable of handling 1,024 actuators with 220V maximum dynamic range, 16bit resolution, and 14bit accuracy, and operating at up to 1kHz frequency. The system fits in a 10x10x5cm volume, weighs less than 0.5kg, and consumes less than 8W. We have developed a turnkey solution reducing the risk for currently planned as well as future missions, lowering their cost by significantly reducing volume, weight and power consumption of the wavefront control hardware.

  4. Deformable mirrors development program at ESO

    Science.gov (United States)

    Stroebele, Stefan; Vernet, Elise; Brinkmann, Martin; Jakob, Gerd; Lilley, Paul; Casali, Mark; Madec, Pierre-Yves; Kasper, Markus

    2016-07-01

    Over the last decade, adaptive optics has become essential in different fields of research including medicine and industrial applications. With this new need, the market of deformable mirrors has expanded a lot allowing new technologies and actuation principles to be developed. Several E-ELT instruments have identified the need for post focal deformable mirrors but with the increasing size of the telescopes the requirements on the deformable mirrors become more demanding. A simple scaling up of existing technologies from few hundred actuators to thousands of actuators will not be sufficient to satisfy the future needs of ESO. To bridge the gap between available deformable mirrors and the future needs for the E-ELT, ESO started a development program for deformable mirror technologies. The requirements and the path to get the deformable mirrors for post focal adaptive optics systems for the E-ELT is presented.

  5. Pulse compression by use of deformable mirrors.

    Science.gov (United States)

    Zeek, E; Maginnis, K; Backus, S; Russek, U; Murnane, M; Mourou, G; Kapteyn, H; Vdovin, G

    1999-04-01

    An electrostatically deformable, gold-coated, silicon nitride membrane mirror was used as a phase modulator to compress pulses from 92 to 15 fs. Both an iterative genetic algorithm and single-step dispersion compensation based on frequency-resolved optical gating calibration of the mirror were used to compress pulses to within 10% of the transform limit. Frequency-resolved optical gating was used to characterize the pulses and to test the range of the deformable-mirror-based compressor.

  6. Driver ASICs for Advanced Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The program leverages on our extensive expertise in developing high-performance driver ASICs for deformable mirror systems and seeks to expand the capacities of the...

  7. High Resolution Silicon Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal describes a plan to build a prototype small stroke, high precision deformable mirror suitable for space-based operation in systems for high-resolution...

  8. High Resolution Silicon Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this proposal we describe a plan to build a deformable mirror suitable for space-based operation in systems for high-resolution imaging. The prototype DM will be...

  9. Active Beam Shaping System and Method Using Sequential Deformable Mirrors

    Science.gov (United States)

    Norman, Colin A. (Inventor); Pueyo, Laurent A. (Inventor)

    2015-01-01

    An active optical beam shaping system includes a first deformable mirror arranged to at least partially intercept an entrance beam of light and to provide a first reflected beam of light, a second deformable mirror arranged to at least partially intercept the first reflected beam of light from the first deformable mirror and to provide a second reflected beam of light, and a signal processing and control system configured to communicate with the first and second deformable mirrors. The first deformable mirror, the second deformable mirror and the signal processing and control system together provide a large amplitude light modulation range to provide an actively shaped optical beam.

  10. Deformable Mirrors Capture Exoplanet Data, Reflect Lasers

    Science.gov (United States)

    2014-01-01

    To image and characterize exoplanets, Goddard Space Flight Center turned to deformable mirrors (DMs). Berkeley, California-based Iris AO, Inc. worked with Goddard through the SBIR program to improve the company’s microelectromechanical DMs, which are now being evaluated and used for biological research, industrial applications, and could even be used by drug manufacturers.

  11. Cryogenic wavefront correction using membrane deformable mirrors.

    Science.gov (United States)

    Dyson, H; Sharples, R; Dipper, N; Vdovin, G

    2001-01-01

    Micro-machined membrane deformable mirrors (MMDMs) are being evaluated for their suitability as wavefront correctors at cryogenic temperatures. Presented here are experimental results for the change in the initial mirror figure of 37-channel MMDMs from OKO Technologies upon cooling to T=78K. The changes in the influence functions are also explored. Of the sample of 3 mirrors tested, one was found to have sufficiently small initial static aberrations to be useful as a wavefront corrector at this temperature. The influence functions at T=78K were found to be similar in shape to both those at room temperature and theoretical predictions of the MMDMs surface shape. The magnitude of the surface deflection at T=78K was reduced by around 20% compared with room temperature values.

  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. MetaSensing's FastGBSAR: ground based radar for deformation monitoring

    Science.gov (United States)

    Rödelsperger, Sabine; Meta, Adriano

    2014-10-01

    The continuous monitoring of ground deformation and structural movement has become an important task in engineering. MetaSensing introduces a novel sensor system, the Fast Ground Based Synthetic Aperture Radar (FastGBSAR), based on innovative technologies that have already been successfully applied to airborne SAR applications. The FastGBSAR allows the remote sensing of deformations of a slope or infrastructure from up to a distance of 4 km. The FastGBSAR can be setup in two different configurations: in Real Aperture Radar (RAR) mode it is capable of accurately measuring displacements along a linear range profile, ideal for monitoring vibrations of structures like bridges and towers (displacement accuracy up to 0.01 mm). Modal parameters can be determined within half an hour. Alternatively, in Synthetic Aperture Radar (SAR) configuration it produces two-dimensional displacement images with an acquisition time of less than 5 seconds, ideal for monitoring areal structures like dams, landslides and open pit mines (displacement accuracy up to 0.1 mm). The MetaSensing FastGBSAR is the first ground based SAR instrument on the market able to produce two-dimensional deformation maps with this high acquisition rate. By that, deformation time series with a high temporal and spatial resolution can be generated, giving detailed information useful to determine the deformation mechanisms involved and eventually to predict an incoming failure. The system is fully portable and can be quickly installed on bedrock or a basement. The data acquisition and processing can be fully automated leading to a low effort in instrument operation and maintenance. Due to the short acquisition time of FastGBSAR, the coherence between two acquisitions is very high and the phase unwrapping is simplified enormously. This yields a high density of resolution cells with good quality and high reliability of the acquired deformations. The deformation maps can directly be used as input into an Early

  14. Design of deformable mirrors for high power lasers

    Institute of Scientific and Technical Information of China (English)

    Stefano Bonora; Jan Pilar; Antonio Lucianetti; Tomas Mocek

    2016-01-01

    We present the workflow of the design, realization and testing of deformable mirrors suitable for high power diode pumped solid-state lasers. It starts with the study of the aberration to be corrected, and then it continues with the design of the actuators position and characteristic. In this paper, we present and compare three deformable mirrors realized for multi-J level laser facilities. We show that with the same design concept it is possible to realize deformable mirrors for other types of lasers. As an example, we report the realization of a deformable mirror for femtosecond lasers and for a CW CO2 laser.

  15. Advanced Actuator Concepts for High Precision Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes to develop a variety of single crystal actuators for adaptive optics deformable mirrors. Single crystal piezoelectric actuators are...

  16. Actuators of 3-element unimorph deformable mirror

    Science.gov (United States)

    Fu, Tianyang; Ning, Yu; Du, Shaojun

    2016-10-01

    Kinds of wavefront aberrations exist among optical systems because of atmosphere disturbance, device displacement and a variety of thermal effects, which disturb the information of transmitting beam and restrain its energy. Deformable mirror(DM) is designed to adjust these wavefront aberrations. Bimorph DM becomes more popular and more applicable among adaptive optical(AO) systems with advantages in simple structure, low cost and flexible design compared to traditional discrete driving DM. The defocus aberration accounted for a large proportion of all wavefront aberrations, with a simpler surface and larger amplitude than others, so it is very useful to correct the defocus aberration effectively for beam controlling and aberration adjusting of AO system. In this study, we desired on correcting the 3rd and 10th Zernike modes, analyze the characteristic of the 3rd and 10th defocus aberration surface distribution, design 3-element actuators unimorph DM model study on its structure and deformation principle theoretically, design finite element models of different electrode configuration with different ring diameters, analyze and compare effects of different electrode configuration and different fixing mode to DM deformation capacity through COMSOL finite element software, compare fitting efficiency of DM models to the 3rd and 10th Zernike modes. We choose the inhomogeneous electrode distribution model with better result, get the influence function of every electrode and the voltage-PV relationship of the model. This unimorph DM is suitable for the AO system with a mainly defocus aberration.

  17. The deformable mirror method of adaptive phase correction

    Institute of Scientific and Technical Information of China (English)

    Bin Tang(唐斌); Yuxin Leng(冷雨欣); Hanlin Peng(朋汉林); Zhengquan Zhang(张正泉); Lihuang Lin(林礼煌)

    2003-01-01

    In this paper, a simple method of phase correction by using a micromachined deformable mirror (MMDM)is demonstrated. With correction of high-order phases due to propagating through medium, we obtaineda clean pulse shape, flattened spectral phase and decreased the femtosecond laser pulse duration. It isshown by our experiment that the deformable mirror is an effective and easy method for adaptive phasecorrection.

  18. Designing optimized ultra-lightweighted mirror structures made of Cesic for space and ground based applications

    Science.gov (United States)

    Hofbauer, Peter; Krödel, Matthias R.

    2010-07-01

    Today's space applications increasingly utilize lightweighted construction concepts, motivated by the demands of manufacturing and functionality, and by economics. Particularly for space optics, mirror stability and stiffness need to be maximized, while mass needs to be minimized. Therefore, mirror materials must possess, besides high material strength and manufacturing versatility, high thermal conductivity combined with low heat capacity and long-term stability against varying thermal loads. Additionally, optical surfaces need to be compatible with reflective coating materials. In order to achieve these requirements, the interplay between material properties and mirror design on one hand, and budgetary constraints on the other must be considered. In this paper, we address these issues by presenting an FEM design study of open and closed-back mirror structures with extremely thin reinforcing ribs, with the goal of obtaining optimal physical and optical characteristics. Furthermore, we show that ECM's carbon-fiber reinforced SiC composite, Cesic®, and its newly developed, HB-Cesic® , with their low CTE, low density, and high stiffness, are not only excellent mirror materials, but allow the rapid manufacturing of complex monolithic optical structures at reasonable cost.

  19. Correction of low order aberrations using continuous deformable mirrors.

    Science.gov (United States)

    Vdovin, Gleb; Soloviev, Oleg; Samokhin, Alexander; Loktev, Mikhail

    2008-03-03

    By analyzing the Poisson equation describing the static behavior of membrane and bimorph deformable mirrors and biharmonic equation describing the continuous facesheet mirror with push-pull actuators, we found that to achieve a high quality correction of low-order aberrations these mirrors should have sufficient number of actuators positioned outside the correction aperture. In particular, any deformable mirror described by the Poisson equation requires at least two actuators to be placed outside the working aperture per period of the azimuthal aberration of the highest expected order. Any deformable mirror described by the biharmonic equation, such as a continuous facesheet mirror with push-pull actuators, requires at least four actuators to be placed outside the working aperture per period of the azimuthal aberration of the highest expected order, and these actuators should not be positioned on a single circle.

  20. 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.

  1. Global feedforward and glocal feedback control of large deformable mirrors

    Science.gov (United States)

    Ruppel, Thomas; Sawodny, Oliver

    2011-09-01

    With an increasing demand for high spatial resolution and fast temporal response of AO components for ELTs, the need for actively controlled, electronically damped deformable mirrors is evident. With typically more than 1000 actuators and collocated sensors, the evolving multi-input multi-output control task for shaping the deformable mirror requires sophisticated control concepts. Although global position control of the mirror would be the most promising solution, the computational complexity for high order spatial control of the deformable element typically exceeds available computing power. Due to this reason, existing deformable membrane mirrors for large telescopes incorporate local feedback instead of global feedback control and neglect some of the global dynamics of the deformable mirror. As a side effect, coupling of the separately controlled actuators through the deformable membrane can lead to instability of the individually stable loops and draws the need for carefully designing the control parameters of the local feedback loops. In this presentation, the computational demands for global position control of deformable mirrors are revisited and a less demanding model-based modal control concept for large deformable membrane mirrors with distributed force actuators and collocated position sensors is presented. Both global feedforward and glocal feedback control is employed in a two-degree-of-freedom control structure allowing for separately designing tracking performance and disturbance rejection. In order to implement state feedback control, non-measureable state information is reconstructed by using model-based distributed state observers. By taking into account the circular symmetry of the deformable mirror geometry, the computational complexity of the algorithms is discussed and model reduction techniques with quasi-static state approximation are presented. As an example, the geometric layout of required sensor / actuator wiring and computational

  2. Active optics: deformable mirrors with a minimum number of actuators

    CERN Document Server

    Laslandes, Marie; Ferrari, Marc; 10.2971/jeos.2012.12036

    2012-01-01

    We present two concepts of deformable mirror to compensate for first order optical aberrations. Deformation systems are designed using both elasticity theory and Finite Element Analysis in order to minimize the number of actuators. Starting from instrument specifications, we explain the methodology to design dedicated deformable mirrors. The work presented here leads to correcting devices optimized for specific functions. The Variable Off-Axis paraboLA concept is a 3-actuators, 3-modes system able to generate independently Focus, Astigmatism and Coma. The Correcting Optimized Mirror with a Single Actuator is a 1-actuator system able to generate a given combination of optical aberrations.

  3. Deformable Membrane Mirror for Wavefront Correction (Short Communication

    Directory of Open Access Journals (Sweden)

    Amita Gupta

    2009-11-01

    Full Text Available Deformable or adaptive mirrors are used in modern adaptive optics systems for direct correction of the aberrations in the light wavefront. Conventional deformable mirrors used for this purpose are expensive electromechanical devices. Deformable membrane mirror fabricated using microelectromechanical systems (MEMS technology is a low cost, compact adaptive optical element for correction of the lower-order optical aberrations such as defocus and astigmatism. In this paper, important aspects of device design and simulation, fabrication techniques, and test results are discussed.Defence Science Journal, 2009, 59(6, pp.590-594, DOI:http://dx.doi.org/10.14429/dsj.59.1563

  4. Structure modulated electrostatic deformable mirror for focus and geometry control.

    Science.gov (United States)

    Nam, Saekwang; Park, Suntak; Yun, Sungryul; Park, Bongje; Park, Seung Koo; Kyung, Ki-Uk

    2016-01-11

    We suggest a way to electrostatically control deformed geometry of an electrostatic deformable mirror (EDM) based on geometric modulation of a basement. The EDM is composed of a metal coated elastomeric membrane (active mirror) and a polymeric basement with electrode (ground). When an electrical voltage is applied across the components, the active mirror deforms toward the stationary basement responding to electrostatic attraction force in an air gap. Since the differentiated gap distance can induce change in electrostatic force distribution between the active mirror and the basement, the EDMs are capable of controlling deformed geometry of the active mirror with different basement structures (concave, flat, and protrusive). The modulation of the deformed geometry leads to significant change in the range of the focal length of the EDMs. Even under dynamic operations, the EDM shows fairly consistent and large deformation enough to change focal length in a wide frequency range (1~175 Hz). The geometric modulation of the active mirror with dynamic focus tunability can allow the EDM to be an active mirror lens for optical zoom devices as well as an optical component controlling field of view.

  5. Single Crystal Bimorph Array (SCBA) Driven Deformable Mirror (DM) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research (SBIR) Phase II project will research a novel deformable mirror design for NASA adaptive optics telescope applications. The...

  6. Single Crystal Bimorph Array Driven Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research (SBIR) Phase I project will research a novel deformable mirror design for NASA adaptive optics telescope applications . The...

  7. Extreme-Precision MEMS Segmented Deformable Mirror Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In Phase I research, Iris AO developed enhanced electromechanical models and calibration techniques for MEMS-based segmented deformable mirrors (DMs) applicable to a...

  8. Compact Low-Power Driver for Deformable Mirror Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Boston Micromachines Corporation (BMC), a leading developer of unique, high-resolution micromachined deformable mirrors (DMs), will develop a compact, low-power,...

  9. Unimorph deformable mirror for space telescopes: design and manufacturing.

    Science.gov (United States)

    Rausch, Peter; Verpoort, Sven; Wittrock, Ulrich

    2015-07-27

    Large space telescopes made of deployable and lightweight structures suffer from aberrations caused by thermal deformations, gravitational release, and alignment errors which occur during the deployment procedure. An active optics system would allow on-site correction of wave-front errors, and ease the requirements on thermal and mechanical stability of the optical train. In the course of a project funded by the European Space Agency we have developed and manufactured a unimorph deformable mirror based on piezoelectric actuation. The mirror is able to work in space environment and is designed to correct for large aberrations of low order with high surface fidelity. This paper discusses design, manufacturing and performance results of the deformable mirror.

  10. 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.

  11. Driver ASICs for Advanced Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of the SBIR program is to develop a new Application Specified Integrated Circuit (ASIC) driver to be used in driver electronics of a deformable...

  12. 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.

  13. Liquid deformable mirror for high-order wavefront correction

    NARCIS (Netherlands)

    Vuelban, E.M.; Bhattacharya, N.; Braat, J.J.M.

    2006-01-01

    We propose and demonstrate a novel liquid deformable mirror, based on electrocapillary actuation, for highorder wavefront correction. The device consists of a two-dimensional array of vertically oriented microchannels filled with two immiscible liquids, an aqueous electrolyte, and a viscous dielectr

  14. Ultrabroadband pulse shaping with a push-pull deformable mirror.

    Science.gov (United States)

    Bonora, Stefano; Brida, Daniele; Villoresi, Paolo; Cerullo, Giulio

    2010-10-25

    We report the programmable pulse shaping of ultrabroadband pulses by the use of a novel design of electrostatic deformable mirror based on push pull technology. We shape few-optical pulses from near-IR and visible optical parametric amplifiers, and demonstrate strong-field control of excited state population transfer in a dye molecule.

  15. A decomposition approach to distributed control of dynamic deformable mirrors

    NARCIS (Netherlands)

    Fraanje, P.R.; Massioni, P.; Verhaegen, M.

    2010-01-01

    Deformable mirrors with spatially invariant dynamic response can be considered as part of the class of decomposable systems. Such systems can be thought of as the interconnection of a number of identical subsystems, and they can be used to model certain classes of large scale systems. We show in thi

  16. Actuator tests for a large deformable membrane mirror

    NARCIS (Netherlands)

    Hamelinck, R.; Rosielle, N.; Steinbuch, M.; Ellenbroek, R.; Verhagen, M.; Doelman, N.

    2006-01-01

    In the design of a large adaptive deformable membrane mirror, variable reluctance actuators are used. These consist of a closed magnetic circuit in which a strong permanent magnet provides a static magnetic force on a ferromagnetic core which is suspended in a membrane. By applying a current through

  17. Actuator tests for a large deformable membrane mirror

    NARCIS (Netherlands)

    Hamelinck, R.; Rosielle, N.; Steinbuch, M.; Ellenbroek, R.; Verhagen, M.; Doelman, N.

    2006-01-01

    In the design of a large adaptive deformable membrane mirror, variable reluctance actuators are used. These consist of a closed magnetic circuit in which a strong permanent magnet provides a static magnetic force on a ferromagnetic core which is suspended in a membrane. By applying a current through

  18. Large adaptive deformable mirror: design and first prototypes

    NARCIS (Netherlands)

    Hamelinck, R.F.M.M.; Rosielle, P.C.J.N.; Steinbuch, M.; Doelman, N.J.

    2005-01-01

    The first prototype of an actuator for a new adaptive deformable mirror (DM) is presented together with the development of a 61-actuator grid element. The DM design consists of a thin membrane which acts as the correcting element. A grid of low voltage electro-magnetic push-pull actuators, impose ou

  19. Surface Slope Metrology on Deformable Soft X-ray Mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Sheng; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Celestre, Rich; Church, Matthew; McKinney, Wayne R.; Morrison, Greg; Warwick, Tony

    2010-01-31

    We report on the current state of surface slope metrology on deformable mirrors for soft x-rays at the Advanced Light Source (ALS). While we are developing techniques for in situ at-wavelength tuning, we are refining methods of ex situ visible-light optical metrology to achieve sub-100-nrad accuracy. This paper reports on laboratory studies, measurements and tuning of a deformable test-KB mirror prior to its use. The test mirror was bent to a much different optical configuration than its original design, achieving a 0.38 micro-radian residual slope error. Modeling shows that in some cases, by including the image conjugate distance as an additional free parameter in the alignment, along with the two force couples, fourth-order tangential shape errors (the so-called bird shape) can be reduced or eliminated.

  20. Surface Slope Metrology on Deformable Soft X-ray Mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, S.; Yashchuk, V.V.; Goldberg, K.A.; Celestre, R.; Church, M.; McKinney, W.R.; Morrison, G.; Warwick, T.

    2009-09-18

    We report on the current state of surface slope metrology on deformable mirrors for soft x-rays at the Advanced Light Source (ALS). While we are developing techniques for in situ at-wavelength tuning, we are refining methods of ex situvisible-light optical metrology to achieve sub-100-nrad accuracy. This paper reports on laboratory studies, measurements and tuning of a deformable test-KB mirror prior to its use. The test mirror was bent to a much different optical configuration than its original design, achieving a 0.38 micro-radian residual slope error. Modeling shows that in some cases, by including the image conjugate distance as an additional free parameter in the alignment, along with the two force couples, fourth-order tangential shape errors (the so-called bird shape) can be reduced or eliminated.

  1. Lightweight In-Plane Actuated Deformable Mirrors for Space Telescopes

    Science.gov (United States)

    2006-09-01

    a reflective surface, such as a deformable mirror. The Michelson Interferometer, as described by Hecht [63], uses a beam splitter to divide a laser...Columbia University [90, pp. 281-290]. During the period of the lectures, the “ monolithic crys- tal filter” was discovered independently by researchers in...through a monolithic lenslet module (MLM) that focuses the light onto an RS-170v monochrome Shack-Hartmann wavefront sensor. The fidelity of the data

  2. X-ray beam-shaping via deformable mirrors: analytical computation of the required mirror profile

    CERN Document Server

    Spiga, Daniele; Svetina, Cristian; Zangrando, Marco; 10.1016/j.nima.2012.10.117

    2013-01-01

    X-ray mirrors with high focusing performances are in use in both mirror mod- ules for X-ray telescopes and in synchrotron and FEL (Free Electron Laser) beamlines. A degradation of the focus sharpness arises in general from geo- metrical deformations and surface roughness, the former usually described by geometrical optics and the latter by physical optics. In general, technological developments are aimed at a very tight focusing, which requires the mirror profile to comply with the nominal shape as much as possible and to keep the roughness at a negligible level. However, a deliberate deformation of the mirror can be made to endow the focus with a desired size and distribution, via piezo actuators as done at the EIS-TIMEX beamline of FERMI@Elettra. The resulting profile can be characterized with a Long Trace Profilometer and correlated with the expected optical quality via a wavefront propagation code. However, if the roughness contribution can be neglected, the com- putation can be performed via a ray-tracin...

  3. Membrane based Deformable Mirror: Intrinsic aberrations and alignment issues

    CERN Document Server

    Bayanna, A Raja; Chatterjee, S; Mathew, Shibu K; Venkatakrishnan, P

    2015-01-01

    A Deformable Mirror (DM) is an important component of an Adaptive Optics system. It is known that an on-axis spherical/parabolic optical component, placed at an angle to the incident beam introduces defocus as well as astigmatism in the image plane. Although the former can be compensated by changing the focal plane position, the latter cannot be removed by mere optical re-alignment. Since the DM is to be used to compensate a turbulence-induced curvature term in addition to other aberrations, it is necessary to determine the aberrations induced by such (curved DM surface) an optical element when placed at an angle (other than 0 degree) of incidence in the optical path. To this effect, we estimate to a first order, the aberrations introduced by a DM as a function of the incidence angle and deformation of the DM surface. We record images using a simple setup in which the incident beam is reflected by a 37 channel Micro-machined Membrane Deformable Mirror for various angles of incidence. It is observed that astig...

  4. Correction of an active space telescope mirror using a deformable mirror in a woofer-tweeter configuration

    Science.gov (United States)

    Allen, Matthew R.; Kim, Jae Jun; Agrawal, Brij N.

    2016-04-01

    The Naval Postgraduate School's segmented mirror telescope (SMT) was developed using prototype silicon carbide active hybrid mirror technology to demonstrate lower cost and rapid manufacture of primary mirror segments for a space telescope. The developmental mirror segments used too few actuators limiting the ability to adequately correct the surface figure error. To address the unintended shortfall of the developmental mirrors, a deformable mirror is added to the SMT and control techniques are developed. The control techniques are similar to woofer-tweeter adaptive optics, where the SMT segment represents the woofer and the deformable mirror represents the tweeter. The optical design of an SMT woofer-tweeter system is presented, and the impacts of field angle magnification on the placement and size of the deformable mirror are analyzed. A space telescope woofer-tweeter wavefront control technique is proposed using a global influence matrix and closed-loop constrained minimization controller. The control technique simultaneously manipulates the woofer and tweeter mirrors. Simulation and experimental results demonstrate a significant improvement in wavefront error of the primary mirror and the control technique shows significant wavefront error improvement compared to sequentially controlling the woofer and tweeter mirrors.

  5. Wavefront correction with a ferrofluid deformable mirror: experimental results and recent developments

    CERN Document Server

    Brousseau, Denis; Thibaul, Simon; Ritcey, Anna M; Parent, Jocelyn; Seddiki, Omar; Dery, Jean-Philippe; Faucher, Luc; Vassallo, Julien; Naderian, Azadeh

    2008-01-01

    We present the research status of a deformable mirror made of a magnetic liquid whose surface is actuated by a triangular array of small current carrying coils. We demonstrate that the mirror can correct a 11 microns low order aberrated wavefront to a residual RMS wavefront error 0.05 microns. Recent developments show that these deformable mirrors can reach a frequency response of several hundred hertz. A new method for linearizing the response of these mirrors is also presented.

  6. Hybrid Electrostatic/Flextensional Deformable Membrane Mirror for Lightweight, Large Aperture and Cryogenic Space Telescopes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes innovative hybrid electrostatic/flextensional membrane deformable mirror capable of large amplitude aberration correction for large...

  7. The DeMi CubeSat: Wavefront Control with a MEMS Deformable Mirror in Space

    Science.gov (United States)

    Douglas, Ewan S.; Bendek, Eduardo; Marinan, Anne; Belikov, Ruslan; Merck, John; Cahoy, Kerri Lynn

    2017-01-01

    High-contrast imaging instruments on future space telescopes will require precise wavefront correction to detect small exoplanets near their host stars. High-actuator count microelectromechanical system (MEMS) deformable mirrors provide a compact form of wavefront control. The 6U DeMi CubeSat will demonstrate wavefront control with a MEMS deformable mirror over a yearlong mission. The payload includes both an internal laser source and a small telescope, with both focal plane and pupil plane sensing, for deformable mirror characterization. We detail the DeMi payload design, and describe future astrophysics enabled by high-actuator count deformable mirrors and small satellites.

  8. A new deformable mirror architecture for coronagraphic instrumentation

    Science.gov (United States)

    Groff, Tyler D.; Lemmer, Aaron; Eldorado Riggs, A. J.

    2016-07-01

    Coronagraphs are a promising solution for the next generation of exoplanet imaging instrumentation. While a coronagraph can have very good contrast and inner working angle performance, it is highly sensitive to optical aberrations. This necessitates a wavefront control system to correct aberrations within the telescope. The wavefront requirements and desired search area in a deformable mirror (DM) demand control of the electric field out to relatively high spatial frequencies. Conventional wisdom leads us to high stroke, high actuator density DMs that are capable of reaching these spatial frequencies on a single surface. Here we model a different architecture, where nearly every optical surface, powered or unpowered, is a controllable element. Rather than relying on one or two controllable surfaces for the success of the entire instrument the modeled instrument consists of a series of lower actuator count deformable mirrors to achieve the same result by leveraging the conjugate planes that exist in a coronagraphic instrument. To make such an instrument concept effective the imaging optics themselves must become precision deformable elements, akin to the deformable secondary mirrors at major telescope facilities. Such a DM does not exist commercially; all current DMs, while not necessarily incapable of carrying optical power, are manufactured with flat nominal surfaces. This simplifies control and manufacturing, but complicates their integration into an optical system because there is oftentimes a need to pack several into collimated space. Furthermore, high actuator count DMs cannot approximate low order shapes such as focus or tip-tilt without significant mid-spatial frequency residuals, which is not acceptable for a coronagraphic high-contrast imager. The ability to integrate the wavefront control system into the nominal coronagraphic optical train simplifies packaging, reduces cost and complexity, and increases optical throughput of any coronagraphic instrument

  9. Modeling of microelectromechanical systems deformable mirror diffraction grating

    Science.gov (United States)

    Sirbu, Dan; Pluzhnik, Eugene; Belikov, Ruslan

    2016-07-01

    Model-based wavefront control methods such as electric field conjugation require accurate optical propagation models to create high-contrast regions in the focal plane using deformable mirrors (DMs). Recently, it has been shown that it is possible to exceed the controllable outer-working angle imposed by the Nyquist limit based on the number of actuators by utilizing a diffraction grating. The print-through pattern on MEMS-based DMs formed during the fabrication process creates both an amplitude and a phase diffraction grating that can be used to enable Super-Nyquist wavefront control. Using interferometric measurements of a DM-actuator, we develop a DM-diffraction grating model. We compare the total energy enclosed in the first diffraction order due to the phase, amplitude, and combined phase-amplitude gratings with laboratory measurements.

  10. Control x-ray deformable mirrors with few measurements

    Science.gov (United States)

    Huang, Lei; Xue, Junpeng; Idir, Mourad

    2016-09-01

    After years of development from a concept to early experimental stage, X-ray Deformable Mirrors (XDMs) are used in many synchrotron/free-electron laser facilities as a standard x-ray optics tool. XDM is becoming an integral part of the present and future large x-ray and EUV projects and will be essential in exploiting the full potential of the new sources currently under construction. The main objective of using XDMs is to correct wavefront errors or to enable variable focus beam sizes at the sample. Due to the coupling among the N actuators of a DM, it is usually necessary to perform a calibration or training process to drive the DM into the target shape. Commonly, in order to optimize the actuators settings to minimize slope/height errors, an initial measurement need to be collected, with all actuators set to 0, and then either N or 2N measurements are necessary learn each actuator behavior sequentially. In total, it means that N+1 or 2N+1 scans are required to perform this learning process. When the actuators number N is important and the actuator response or the necessary metrology is slow then this learning process can be time consuming. In this work, we present a fast and accurate method to drive an x-ray active bimorph mirror to a target shape with only 3 or 4 measurements. Instead of sequentially measuring and calculating the influence functions of all actuators and then predicting the voltages needed for any desired shape, the metrology data are directly used to "guide" the mirror from its current status towards the particular target slope/height via iterative compensations. The feedback for the iteration process is the discrepancy in curvature calculated by using B-spline fitting of the measured height/slope data. In this paper, the feasibility of this simple and effective approach is demonstrated with experiments.

  11. High-Resolution Adaptive Optics Scanning Laser Ophthalmoscope with Dual Deformable Mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D C; Jones, S M; Silva, D A; Olivier, S S

    2006-08-11

    Adaptive optics scanning laser ophthalmoscope (AO SLO) has demonstrated superior optical quality of non-invasive view of the living retina, but with limited capability of aberration compensation. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina. We used a bimorph mirror to correct large-stroke, low-order aberrations and a MEMS mirror to correct low-stroke, high-order aberration. The measured ocular RMS wavefront error of a test subject was 240 nm without AO compensation. We were able to reduce the RMS wavefront error to 90 nm in clinical settings using one deformable mirror for the phase compensation and further reduced the wavefront error to 48 nm using two deformable mirrors. Compared with that of a single-deformable-mirror SLO system, dual AO SLO offers much improved dynamic range and better correction of the wavefront aberrations. The use of large-stroke deformable mirrors provided the system with the capability of axial sectioning different layers of the retina. We have achieved diffraction-limited in-vivo retinal images of targeted retinal layers such as photoreceptor layer, blood vessel layer and nerve fiber layers with the combined phase compensation of the two deformable mirrors in the AO SLO.

  12. A new concept for large deformable mirrors for extremely large telescopes

    Science.gov (United States)

    Andersen, Torben; Owner-Petersen, Mette; Ardeberg, Arne; Korhonen, Tapio

    2006-06-01

    For extremely large telescopes, there is strong need for thin deformable mirrors in the 3-4 m class. So far, feasibility of such mirrors has not been demonstrated. Extrapolation from existing techniques suggests that the mirrors could be highly expensive. We give a progress report on a study of an approach for construction of large deformable mirrors with a moderate cost. We have developed low-cost actuators and deflection sensors that can absorb mounting tolerances in the millimeter range, and we have tested prototypes in the laboratory. Studies of control laws for mirrors with thousands of sensors and actuators are in good progress and simulations have been carried out. Manufacturing of thin, glass mirror blanks is being studied and first prototypes have been produced by a slumping technique. Development of polishing procedures for thin mirrors is in progress.

  13. 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.

  14. An RF Therapy System for Breast Cancer Using Dual Deformable Mirrors — Computational Study

    Science.gov (United States)

    Arunachalam, Kavitha; Udpa, Satish S.; Udpa, Lalita

    2007-03-01

    Breast cancer is the second leading cause of cancer deaths amongst women in the United States. In the past two decades, the potential of non-ionizing high power RF waves to destroy cancerous biological tissues is actively investigated for cancer therapy. This paper presents the computational feasibility study of an alternative mode of electromagnetic radiation therapy that employs dual source and deformable mirror. The adaptive focusing capability of the deformable mirror is exploited for preferential energy deposition at the tumor site in the breast irradiated by electromagnetic radiation. The outcome of the computational study for the proposed deformable mirror-based thermal therapy for breast cancer is presented in this paper.

  15. Prototype Small Footprint Amplifier for Piezoelectric Deformable Mirrors

    Science.gov (United States)

    Caputa, Kris; Herriot, Glen; Niebergal, Joel; Zielinski, Adam

    2011-09-01

    AO subsystems of the ELT observatories will incorporate deformable mirrors with an order of magnitude larger number of piezoelectric actuators than the AO systems currently deployed. Simply scaling up the drive electronics that are presently available commercially would substantially drive up the AO cost, pose unacceptably high demands for the supply power and heat dissipation, and occupy large physical volume. We have set out to prototype a high voltage amplifier that is compact enough to allow packaging 100 amplifier channels on a single 6U Eurocard with the goal to have a DM drive channel density of 1200 per 6U VME crate. Individual amplifier circuits should be driven by a multichannel A/D converter, consume no more than 0.5W from the +/-400V power supply, be slew rate limited in hardware, and be short-circuit protected. The component cost should be an order of magnitude less than the integrated circuit high voltage amplifiers currently on the market. We started out with modeling candidate circuits in SPICE, then built physical prototypes using inexpensive off the shelf components. In this paper we present experimental results of exposing several prototype circuits to both normal operating conditions and foreseeable fault conditions. The performance is evaluated against the AO requirements for the output range and bandwidth and the DM actuator safety requirements.

  16. Development of Organic FET (OFET)-Based Flexible Integrated Controller for Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal is to complete process development to make OFET’s on flexible substrates compatible with ultra-lightweight deformable mirrors and to demonstrate...

  17. Single Crystal Piezoelectric Deformable Mirrors with High Actuator Density and Large Stroke Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Single crystal piezoelectric deformable mirrors with high actuator density, fine pitch, large stroke and no floating wires will be developed for future NASA science...

  18. Modeling, Calibration and Control for Extreme-Precision MEMS Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Iris AO will develop electromechanical models and actuator calibration methods to enable open-loop control of MEMS deformable mirrors (DMs) with unprecedented...

  19. Development of a Low Mass, Low Power Deformable Mirror with Integrated Drive Electronics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — "Deformable mirrors (DM) are key to achieving high contrast for any mission to image expolanets. Currently Northrup Grumman Xinetics is the only viable source...

  20. Enhanced Fabrication Processes Development for High Actuator Count Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — It is proposed to advance manufacturing science and technology to improve yield and optical surface figure in high actuator count, high-resolution deformable mirrors...

  1. 10^3 Segment MEMS Deformable-Mirror Process Development Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Iris AO will extend its proven segmented MEMS deformable mirror architecture to large array sizes required for high-contrast astrophysical imagers. Current...

  2. Characterisation of the influence function non-additivities for a 1024-actuator MEMS deformable mirror

    CERN Document Server

    Blain, Celia; Bradley, Colin; Guyon, Olivier; Vogel, Curtis

    2010-01-01

    In order to evaluate the potential of MEMS deformable mirrors for open-loop applications, a complete calibration process was performed on a 1024-actuator mirror. The mirror must be perfectly calibrated to obtain deterministic membrane deflection. The actuator's stroke-voltage relationship and the effect of the non- additivity of the influence functions are studied and finally integrated in an open-loop control process. This experiment aimed at minimizing the residual error obtained in open-loop control.

  3. Numerical modelling of a thin deformable mirror for laser beam control

    CSIR Research Space (South Africa)

    Long, CS

    2010-01-01

    Full Text Available For intra-cavity laser beam control, a small, low-cost deformable mirror is required. This mirror can be used to correct for time- dependent phase aberrations to the laser beam, such as those caused by thermal expansion of materials. A piezoelectric...

  4. High-resolution adaptive optics scanning laser ophthalmoscope with dual deformable mirrors for large aberration correction

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D; Jones, S M; Silva, D A; Olivier, S S

    2007-01-25

    Scanning laser ophthalmoscopes with adaptive optics (AOSLO) have been shown previously to provide a noninvasive, cellular-scale view of the living human retina. However, the clinical utility of these systems has been limited by the available deformable mirror technology. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina, making the AOSLO system a viable, non-invasive, high-resolution imaging tool for clinical diagnostics. We used a bimorph deformable mirror to correct low-order aberrations with relatively large amplitudes. The bimorph mirror is manufactured by Aoptix, Inc. with 37 elements and 18 {micro}m stroke in a 10 mm aperture. We used a MEMS deformable mirror to correct high-order aberrations with lower amplitudes. The MEMS mirror is manufactured by Boston Micromachine, Inc with 144 elements and 1.5 {micro}m stroke in a 3 mm aperture. We have achieved near diffraction-limited retina images using the dual deformable mirrors to correct large aberrations up to {+-} 3D of defocus and {+-} 3D of cylindrical aberrations with test subjects. This increases the range of spectacle corrections by the AO systems by a factor of 10, which is crucial for use in the clinical environment. This ability for large phase compensation can eliminate accurate refractive error fitting for the patients, which greatly improves the system ease of use and efficiency in the clinical environment.

  5. Wide aperture piezoceramic deformable mirrors for aberration correction in high-power lasers

    Institute of Scientific and Technical Information of China (English)

    Vadim Samarkin; Alexander Alexandrov; Gilles Borsoni; Takahisa Jitsuno; Pavel Romanov; Aleksei Rukosuev; Alexis Kudryashov

    2016-01-01

    The deformable mirror with the size of 410 mmstacks was developed. The results ×468 mm controlled by the bimorph piezoceramic plates and multilayer piezoceramic of the measurements of the response functions of all the actuators and of the surface shape of the deformable mirror are presented in this paper. The study of the mirror with a Fizeau interferometer and a Shack–Hartmann wavefront sensor has shown that it was possible to improve the flatness of the surface down to a residual roughness of 0.033 μm(RMS). The possibility of correction of the aberrations in high-power lasers was numerically demonstrated.

  6. VLT DSM, the control system of the largest deformable secondary mirror ever manufactured

    Science.gov (United States)

    Manetti, Mauro; Morandini, Marco; Mantegazza, Paolo; Biasi, Roberto; Andrighettoni, Mario; Gallieni, Daniele

    2014-07-01

    A proven technology for the shape control of large secondary deformable mirrors employs a magnetically levitated contactless solution and relies on voice-coil actuators co-located to capacitive position sensors. The present work focuses on the description of the latest upgrade of this technology, as applied to the Very Large Telescope Deformable Secondary Mirror, the largest continuous facesheet adaptive mirror ever manufactured. The controller is based on a completely decentralized high frequency feedback coupled to a lower frequency improved feedforward. The system enhancements and performances are verified through electromechanical tests.

  7. Hard X-ray nanofocusing using adaptive focusing optics based on piezoelectric deformable mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Goto, Takumi; Nakamori, Hiroki; Sano, Yasuhisa; Matsuyama, Satoshi, E-mail: matsuyama@prec.eng.osaka-u.ac.jp [Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Kimura, Takashi [Research Institute for Electronic Science, Hokkaido University, Kita 21 Nishi 10, Kita-ku, Sapporo 001-0021 (Japan); Kohmura, Yoshiki; Tamasaku, Kenji; Yabashi, Makina; Ishikawa, Tetsuya [SPring-8/RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); Yamauchi, Kazuto [Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Center for Ultra-Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); CREST, JST, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)

    2015-04-15

    An adaptive Kirkpatrick–Baez mirror focusing optics based on piezoelectric deformable mirrors was constructed at SPring-8 and its focusing performance characteristics were demonstrated. By adjusting the voltages applied to the deformable mirrors, the shape errors (compared to a target elliptical shape) were finely corrected on the basis of the mirror shape determined using the pencil-beam method, which is a type of at-wavelength figure metrology in the X-ray region. The mirror shapes were controlled with a peak-to-valley height accuracy of 2.5 nm. A focused beam with an intensity profile having a full width at half maximum of 110 × 65 nm (V × H) was achieved at an X-ray energy of 10 keV.

  8. Hard X-ray nanofocusing using adaptive focusing optics based on piezoelectric deformable mirrors.

    Science.gov (United States)

    Goto, Takumi; Nakamori, Hiroki; Kimura, Takashi; Sano, Yasuhisa; Kohmura, Yoshiki; Tamasaku, Kenji; Yabashi, Makina; Ishikawa, Tetsuya; Yamauchi, Kazuto; Matsuyama, Satoshi

    2015-04-01

    An adaptive Kirkpatrick-Baez mirror focusing optics based on piezoelectric deformable mirrors was constructed at SPring-8 and its focusing performance characteristics were demonstrated. By adjusting the voltages applied to the deformable mirrors, the shape errors (compared to a target elliptical shape) were finely corrected on the basis of the mirror shape determined using the pencil-beam method, which is a type of at-wavelength figure metrology in the X-ray region. The mirror shapes were controlled with a peak-to-valley height accuracy of 2.5 nm. A focused beam with an intensity profile having a full width at half maximum of 110 × 65 nm (V × H) was achieved at an X-ray energy of 10 keV.

  9. Micro drilling using deformable mirror for beam shaping of ultra-short laser pulses

    Science.gov (United States)

    Smarra, Marco; Strube, Anja; Dickmann, Klaus

    2016-03-01

    Using ultra-short laser pulses for micro structuring or drilling applications reduces the thermal influence to the surrounding material. The best achievable beam profile equals a Gaussian beam. Drilling with this beam profile results in cylindrical holes. To vary the shape of the holes, the beam can either be scanned or - for single pulse and percussion drilling - manipulated by masks or lenses. A high flexible method for beam shaping can be realized by using a deformable mirror. This mirror contains a piezo-electric ceramic, which can be deformed by an electric potential. By separating the ceramic into independent controllable segments, the shape of the surface can be varied individually. Due to the closed surface of the mirror, there is no loss of intensity due to diffraction. The mirror deformation is controlled by Zernike polynomials and results e.g. in a lens behavior. In this study a deformable mirror was used to generate e.g. slits in thin steel foils by percussion drilling using ultra-short laser pulses. The influence of the cylindrical deformation to the laser beam and the resulting geometry of the generated holes was studied. It was demonstrated that due to the high update rate up to 150 Hz the mirror surface can be varied in each scan cycle, which results in a high flexible drilling process.

  10. Ultraflat Tip-Tilt-Piston MEMS Deformable Mirror Project

    Data.gov (United States)

    National Aeronautics and Space Administration — It is proposed to develop a process for producing arrays of hexagonal mirror segments with deviation from flatness smaller than 1nm RMS over a 600?m segment span,...

  11. Development and control of kilo-pixel MEMS deformable mirrors and spatial light modulators

    Science.gov (United States)

    Perreault, Julie Ann

    This dissertation describes the development of kilo-pixel micro-electro-mechanical optical-quality surface-micromachined deformable mirrors and spatial light modulators along with scalable control electronics. These silicon-based deformable mirrors have the potential to modulate spatial and temporal features of an optical wavefront with applications in imaging, beam-forming, and optical communication systems. Techniques to improve the manufacturing, quality, and capability of these mirrors are detailed. The new mirror system was characterized and a scalable control system was developed to coordinate and control a large array of mirrors. Three types of kilo-pixel deformable mirrors were created: continuous membrane, segmented membrane, and a hybrid stress-relieved membrane mirrors. This new class of mirrors, deformed using electrostatically actuated surface-normal actuators, have an aperature of 10 mm, a stroke of 2 mum, position repeatability of 3 nm, surface roughness of 12 nm, reflectivity of 91%, and a bandwidth in air of 7 kHz. A custom fabrication process was developed in tandem with a new mirror design to address design and layout issues including packaging, residual stress, reliability, yield, fill factor, and surface topography. A chemo-mechanical polishing process improved the surface quality of the mirrors by decreasing surface roughness from an RMS value of 46nm to 12nm. A gold coating process increased reflectivity from 42% to greater than 91% without introducing a significant amount of stress in the mirror membrane. An alternative actuator design and layout was also developed that achieved an increased stroke of 6 mum, with the potential for even longer stroke with stress reduction. The long stroke capability was realized through introduction of split electrodes, actuation membrane cuts, and a double stacked anchor architecture. A computer-driven electronic system was developed to aid in the electro-mechanical testing of these deformable mirrors. Quasi

  12. Controlling the Focal Length and the Spot Size in Flying Optics by Dual-deformable-mirror-systems

    Institute of Scientific and Technical Information of China (English)

    ZHAO Quanzhong; CHENG Zhaogu; GAO Haijun; CHAI Xiongliang; LUO Hongxin

    2002-01-01

    The models of several dual-deformable-mirror-systems,which can control focal the length and the spot size in flying optics,were introduced and their operating principle and adjusting characteristics were analyzed.The simulation results indicate that dual-deformable-mirror-systems can control the focal length and the spot size.This research is a good guidance to engineering application of dual-deformable-mirror-systems.

  13. Integrated optical design for highly dynamic laser beam shaping with membrane deformable mirrors

    Science.gov (United States)

    Pütsch, Oliver; Stollenwerk, Jochen; Loosen, Peter

    2017-02-01

    The utilization of membrane deformable mirrors has raised its importance in laser materials processing since they enable the generation of highly spatial and temporal dynamic intensity distributions for a wide field of applications. To take full advantage of these devices for beam shaping, the huge amount of degrees of freedom has to be considered and optimized already within the early stage of the optical design. Since the functionality of commercial available ray-tracing software has been mainly specialized on geometric dependencies and their optimization within constraints, the complex system characteristics of deformable mirrors cannot be sufficiently taken into account yet. The main reasons are the electromechanical interdependencies of electrostatic membrane deformable mirrors, namely saturation and mechanical clamping, that result in non-linear deformation. This motivates the development of an integrative design methodology. The functionality of the ray-tracing program ZEMAX is extended with a model of an electrostatic membrane mirror. This model is based on experimentally determined influence functions. Furthermore, software routines are derived and integrated that allow for the compilation of optimization criteria for the most relevant analytically describable beam shaping problems. In this way, internal optimization routines can be applied for computing the appropriate membrane deflection of the deformable mirror as well as for the parametrization of static optical components. The experimental verification of simulated intensity distributions demonstrates that the beam shaping properties can be predicted with a high degree of reliability and precision.

  14. Mirror actively deformed and regulated for applications in space: design and performance

    CERN Document Server

    Laslandes, Marie; Ferrari, Marc; Hourtoule, Claire; Singer, Christian; Devilliers, Christophe; Lopez, Celine; Chazallet, Frederic; 10.1117/1.OE.52.9.091803

    2013-01-01

    The need for both high quality images and lightweight structures is one of the main drivers in space telescope design. An efficient wavefront control system will become mandatory in future large observatories, retaining performance while relaxing specifications in the global system's stability. We present the mirror actively deformed and regulated for applications in space project, which aims to demonstrate the applicability of active optics for future space instrumentation. It has led to the development of a 24-actuator, 90-mm-diameter active mirror, able to compensate for large lightweight primary mirror deformations in the telescope's exit pupil. The correcting system has been designed for expected wavefront errors from 3-m-class lightweight primary mirrors, while also taking into account constraints for space use. Finite element analysis allowed an optimization of the system in order to achieve a precision of correction better than 10 nm rms. A dedicated testbed has been designed to fully characterize the...

  15. Measurement of copper vapour laser-induced deformation of dielectric-coated mirror surface by Michelson interferometer

    Indian Academy of Sciences (India)

    A Wahid; S Kundu; J S B Singh; A K Singh; A Khattar; S K Maurya; J S Dhumal; K Dasgupta

    2014-02-01

    AMichelson interferometer-based technique has been used to measure the deformation of dielectric-coated mirror, caused by an incident repetitive pulsed laser beam with high average power. Minimum measurable deformation of 17 nm is reported.

  16. Research on the optimization of a bimorph piezoelectric deformable mirror based on zeroth-order method

    Science.gov (United States)

    Wang, Hairen; Hu, Lin

    2016-07-01

    The deformable mirror adjusts the mirror surface shape to compensate the wavefront error in the adaptive optics system. Recently, the adaptive optics has been widely used in many applications, such as astronomical telescopes, high power laser systems, etc. These applications require large diameter deformable mirrors with large stroke, high speed and low cost. Thus, the bimorph piezoelectric deformable mirror, which is a good match for the applications, has attracted more and more attentions. In this paper, we use zeroth-order optimization method to optimize the physical parameters of a bimorph piezoelectric deformable mirror that consists of a metal reflective layer deposited on the top of a slim piezoelectric ceramic surface layer. The electrodes are deposited on the bottom of the piezoelectric ceramic layer. The physical parameters to be optimized include the optimal thickness ratio between the piezoelectric layer and reflective layer, inter-electrode distance, and so on. A few reasonable designs are obtained by a comparative study presented for three geometries of electrodes, which are circular, square and hexagon, respectively.

  17. Sub-nanometer flattening of a 45-cm long, 45-actuator x-ray deformable mirror

    CERN Document Server

    Poyneer, L A; Pardini, T; Palmer, D; Brooks, A; Pivovaroff, M J; Macintosh, B

    2014-01-01

    We have built a 45-cm long x-ray deformable mirror of super-polished single-crystal silicon that has 45 actuators along the tangential axis. After assembly the surface height error was 19 nm rms. With use of high-precision visible-light metrology and precise control algorithms, we have actuated the x-ray deformable mirror and flattened its entire surface to 0.7 nm rms controllable figure error. This is, to our knowledge, the first sub-nanometer active flattening of a substrate longer than 15 cm.

  18. Computational feasibility of deformable mirror microwave hyperthermia technique for localized breast tumors.

    Science.gov (United States)

    Arunachalam, Kavitha; Udpa, Satish S; Udpa, Lalita

    2007-11-01

    Computational feasibility of a new non-invasive microwave hyperthermia technique that employs dual deformable mirror is investigated using simplified computational tools and anatomically realistic breast models. The proposed technique employs two pairs of electromagnetic sources and continuously deformable mirrors to focus the electromagnetic radiation at the target site for hyperthermia. The mirror functions like a continuum of radiating elements that offer effective scan coverage inside the breast with efficient field focusing at the target location. The electric field focusing and temperature mapping in the two-dimensional numerical simulations are investigated using wave propagation and bio-heat transfer models respectively. The method of moments, a popular numerical simulation tool, is used to model the electric field maintained by the deformable mirrors for continuous wave excitation. The electromagnetic (EM) energy deposited by the mirrors is used in the steady state bio-heat transfer equation to quantify the temperature distribution inside two-dimensional anatomically realistic breast models. Feasibility of the proposed technique is evaluated using numerical breast models derived from magnetic resonance images of patients with variation in breast density, age and pathology. The computational study indicates preferential EM energy deposition and temperature elevation inside tumor tissue with minimum collateral damage to the neighboring normal tissues. Simulation results obtained for the magnetic resonance (MR) breast data appear promising and indicate the merit in pursuing the investigation using 3D computational models.

  19. Freeform high-speed large-amplitude deformable Piezo Mirrors

    CERN Document Server

    Wapler, Matthias C; Wallrabe, Ulrike

    2013-01-01

    We present a new type of tunable mirror with sharply-featured freeform displacement profiles, large displacements of several 100\\mu m and high operating frequencies close to the kHz range at 15mm diameter. The actuation principle is based on a recently explored "topological" displacement mode of piezo sheets. The prototypes presented here include a rotationally symmetric axicon, a hyperbolic sech-icon and a non-symmetric pyram-icon and are scalable to smaller dimensions. The fabrication process is economic and cleanroom-free, and the optical quality is sufficient to demonstrate the diffraction patterns of the optical elements.

  20. Optimization of electrode geometry and piezoelectric layer thickness of a deformable mirror

    Directory of Open Access Journals (Sweden)

    Nováková Kateřina

    2013-05-01

    Full Text Available Deformable mirrors are the most commonly used wavefront correctors in adaptive optics systems. Nowadays, many applications of adaptive optics to astronomical telescopes, high power laser systems, and similar fast response optical devices require large diameter deformable mirrors with a fast response time and high actuator stroke. In order to satisfy such requirements, deformable mirrors based on piezoelectric layer composite structures have become a subject of intense scientific research during last two decades. In this paper, we present an optimization of several geometric parameters of a deformable mirror that consists of a nickel reflective layer deposited on top of a thin lead zirconate titanate (PZT piezoelectric disk. Honeycomb structure of gold electrodes is deposited on the bottom of the PZT layer. The analysis of the optimal thickness ratio between the PZT and nickel layers is performed to get the maximum actuator stroke using the finite element method. The effect of inter-electrode distance on the actuator stroke and influence function is investigated. Applicability and manufacturing issues are discussed.

  1. Single-plane multiple speckle pattern phase retrieval using a deformable mirror

    DEFF Research Database (Denmark)

    Almoro, Percival F.; Glückstad, Jesper; Hanson, Steen Grüner

    2010-01-01

    A design for a single-plane multiple speckle pattern phase retrieval technique using a deformable mirror (DM) is analyzed within the formalism of complex ABCD-matrices, facilitating its use in conjunction with dynamic wavefronts. The variable focal length DM positioned at a Fourier plane of a lens...

  2. Type Ii/heterotic Duality And Mirror Symmetry (bundle Deformation, String Duality)

    CERN Document Server

    Perevalov, E V

    1998-01-01

    Toric geometry is used to systematically construct Type II compactifications dual to Heterotic models in six dimensions involving singular K3 surfaces as well as vector bundles. Reflexive polyhedra are shown to encode the spectra of the resulting low-energy theories. Finally, the connection between mirror symmetry and deformation of bundles on K3 surfaces is exhibited via string duality.

  3. Large adaptive deformable membrane mirror with high actuator density: design and first prototypes

    NARCIS (Netherlands)

    Hamelinck, R.; Rosielle, N.; Steinbuch, M.; Doelman, N.J.

    2005-01-01

    A large adaptive deformable mirror with high actuator density is presented. The DM consists of a thin continuous membrane which acts as the correcting element. A grid of low voltage electro-magnetical push-pull actuators, - located in an actuator plate -, impose out-of-plane displacements in the mir

  4. Large adaptive deformable membrane mirror with high actuator density: design and first prototypes

    NARCIS (Netherlands)

    Hamelinck, R.; Rosielle, N.; Steinbuch, M.; Doelman, N.J.

    2005-01-01

    A large adaptive deformable mirror with high actuator density is presented. The DM consists of a thin continuous membrane which acts as the correcting element. A grid of low voltage electro-magnetical push-pull actuators, - located in an actuator plate -, impose out-of-plane displacements in the

  5. 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...

  6. Characterization of deformable mirrors for spherical aberration correction in optical sectioning microscopy.

    Science.gov (United States)

    Shaw, Michael; Hall, Simon; Knox, Steven; Stevens, Richard; Paterson, Carl

    2010-03-29

    In this paper we describe the wavefront aberrations that arise when imaging biological specimens using an optical sectioning microscope and generate simulated wavefronts for a planar refractive index mismatch. We then investigate the capability of two deformable mirrors for correcting spherical aberration at different focusing depths for three different microscope objective lenses. Along with measurement and analysis of the mirror influence functions we determine the optimum mirror pupil size and number of spatial modes included in the wavefront expansion and we present measurements of actuator linearity and hysteresis. We find that both mirrors are capable of correcting the wavefront aberration to improve imaging and greatly extend the depth at which diffraction limited imaging is possible.

  7. Design of a white-light interferometric measuring system for co-phasing the primary mirror segments of the next generation of ground-based telescope

    Science.gov (United States)

    Song, Helun; Xian, Hao; Jiang, Wenhan; Rao, Changhui; Wang, Shengqian

    2007-12-01

    With the increase of telescope size, the manufacture of monolithic primaries becomes increasingly difficult. Instead, the use of segmented mirrors, where many individual mirrors (the segments) work together to provide good image quality and an aperture equivalent to that of a large monolithic mirror, is considered a more appropriate strategy. But, with the introduction of large telescope mirror comprised of many individual segments, the problem of insuring a smooth continuous mirror surface (co-phased mirrors) becomes critical. One of the main problems arising in the co-phasing of the segmented mirrors telescope is the problem of measurements of the vertical displacements between the individual segments (piston errors). Because of such mirrors to exhibit diffraction-limited performance, a phasing process is required in order to guarantee that the segments have to be positioned with an accuracy of a fraction of a wavelength of the incoming light.The measurements become especially complicated when the piston error is in order of wavelength fractions. To meet the performance capabilities, a novel method for phasing the segmented mirrors optical system is described. The phasing method is based on a high-aperture Michelson interferometer. The use of an interferometric technique allows the measurement of segment misalignment during daytime with high accuracy, which is a major design guideline. The innovation introduced in the optical design of the interferometer is the simultaneous use of both monochromatic and white-light sources that allows the system to measure the piston error with an uncertainty of 6nm in 50µm range. The description about the expected monochromatic and white-light illumination interferograms and the feasibility of the phasing method are presented here.

  8. Development of a new technology of deformable mirror for ultra intense laser applications

    Energy Technology Data Exchange (ETDEWEB)

    Lefaudeux, Nicolas, E-mail: nlefaudeux@imagine-optic.com [Imagine Optic, 18 rue charles de gaulle, 91400 Orsay (France); Levecq, Xavier; Dovillaire, Guillaume; Ballesta, Jerome; Lavergne, Emeric [Imagine Optic, 18 rue charles de gaulle, 91400 Orsay (France); Sauvageot, Paul; Escolano, Lionnel [ISP System (France)

    2011-10-11

    Adaptive optics is now a standard feature for the current ultra high intensity lasers facilities. Aberration induced by both the optical components and the thermal effects in the amplification stages can be corrected with an adaptive optics system to reach both maximum peak energy and fluence. In this article, we present the development of a new technology of deformable mirror. These mirrors are designed taking into account the needs and specificities of ultra intense laser applications. They provide exceptional stability, optical quality and innovative features like scalability and maintenance of the reflective surface.

  9. Demonstration of a 17 cm robust carbon fiber deformable mirror for adaptive optics

    Energy Technology Data Exchange (ETDEWEB)

    Ammons, S M; Hart, M; Coughenour, B; Romeo, R; Martin, R; Rademacher, M

    2011-09-12

    Carbon-fiber reinforced polymer (CFRP) composite is an attractive material for fabrication of optics due to its high stiffness-to-weight ratio, robustness, zero coefficient of thermal expansion (CTE), and the ability to replicate multiple optics from the same mandrel. We use 8 and 17 cm prototype CFRP thin-shell deformable mirrors to show that residual CTE variation may be addressed with mounted actuators for a variety of mirror sizes. We present measurements of surface quality at a range of temperatures characteristic of mountaintop observatories. For the 8 cm piece, the figure error of the Al-coated reflective surface under best actuator correction is {approx}43 nm RMS. The 8 cm mirror has a low surface error internal to the outer ring of actuators (17 nm RMS at 20 C and 33 nm RMS at -5 C). Surface roughness is low (< 3 nm P-V) at a variety of temperatures. We present new figure quality measurements of the larger 17 cm mirror, showing that the intra-actuator figure error internal to the outer ring of actuators (38 nm RMS surface with one-third the actuator density of the 8 cm mirror) does not scale sharply with mirror diameter.

  10. Study of a wide-aperture combined deformable mirror for high-power pulsed phosphate glass lasers

    Energy Technology Data Exchange (ETDEWEB)

    Samarkin, V V; Aleksandrov, A G; Romanov, P N; Rukosuev, A L; Kudryashov, A V [Moscow State University of Mechanical Engineering, Moscow (Russian Federation); Jitsuno, T [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)

    2015-12-31

    A deformable mirror with the size of 410 × 468 mm controlled by bimorph piezoceramic plates and multilayer piezo stacks is developed. The response functions of individual actuators and the measurements of the flatness of the deformable mirror surface are presented. The study of mirrors with an interferometer and a wavefront sensor has shown that it is possible to improve the surface flatness down to a residual roughness of 0.033 μm (RMS). The possibility of correction of beam aberrations in an ultra-high-power laser using the created bimorph mirror is demonstrated. (letters)

  11. Scalable stacked array piezoelectric deformable mirror for astronomy and laser processing applications.

    Science.gov (United States)

    Wlodarczyk, Krystian L; Bryce, Emma; Schwartz, Noah; Strachan, Mel; Hutson, David; Maier, Robert R J; Atkinson, David; Beard, Steven; Baillie, Tom; Parr-Burman, Phil; Kirk, Katherine; Hand, Duncan P

    2014-02-01

    A prototype of a scalable and potentially low-cost stacked array piezoelectric deformable mirror (SA-PDM) with 35 active elements is presented in this paper. This prototype is characterized by a 2 μm maximum actuator stroke, a 1.4 μm mirror sag (measured for a 14 mm × 14 mm area of the unpowered SA-PDM), and a ±200 nm hysteresis error. The initial proof of concept experiments described here show that this mirror can be successfully used for shaping a high power laser beam in order to improve laser machining performance. Various beam shapes have been obtained with the SA-PDM and examples of laser machining with the shaped beams are presented.

  12. Continuous optical zoom module based on two deformable mirrors for mobile device applications

    Science.gov (United States)

    Lin, Yu-Hung; Su, Guo-Dung J.

    2011-10-01

    In recent years, optical zoom function of the mobile camera phones has been studied. However, traditional systems use motors to change separation of lenses to achieve zoom function, suffering from long total length and high power consumption, which is not suitable for mobile phones use. Adopting MEMS polymer deformable mirrors in zoom systems has the potential to reduce thickness and have the advantage of low chromatic aberration. In this paper, we presented a 2X continuous optical zoom systems for mobile phones, using two deformable mirrors, suitable for 5-Mega-pixel image sensors. In our design, the thickness of the zoom system is about 11 mm. The smallest EFL (effective focal length) is 4.7 mm at full field angle of 52° and the f/# is 4.4. The longest EFL of the module is 9.4 mm and the f/# is 6.4.

  13. Woofer-tweeter deformable mirror control for closed-loop adaptive optics: theory and practice

    CERN Document Server

    Gavel, Donald

    2014-01-01

    Deformable mirrors with very high order correction generally have smaller dynamic range of motion than what is required to correct seeing over large aperture telescopes. As a result, systems will need to have an architecture that employs two deformable mirrors in series, one for the low-order but large excursion parts of the wavefront and one for the finer and smaller excursion components. The closed-loop control challenge is to a) keep the overall system stable, b) avoid the two mirrors using control energy to cancel each other's correction, c) resolve actuator saturations stably, d) assure that on average the mirrors are each correcting their assigned region of spatial frequency space. We present the control architecture and techniques for assuring that it is linear and stable according to the above criteria. We derived the analytic forms for stability and performance and show results from simulations and on-sky testing using the new ShaneAO system on the Lick 3-meter telescope.

  14. Wavefront correction performed by a deformable mirror of arbitrary actuator pattern within a multireflection waveguide.

    Science.gov (United States)

    Ma, Xingkun; Huang, Lei; Bian, Qi; Gong, Mali

    2014-09-10

    The wavefront correction ability of a deformable mirror with a multireflection waveguide was investigated and compared via simulations. By dividing a conventional actuator array into a multireflection waveguide that consisted of single-actuator units, an arbitrary actuator pattern could be achieved. A stochastic parallel perturbation algorithm was proposed to find the optimal actuator pattern for a particular aberration. Compared with conventional an actuator array, the multireflection waveguide showed significant advantages in correction of higher order aberrations.

  15. Swept source optical coherence tomography Gabor fusion splicing technique for microscopy of thick samples using a deformable mirror

    Science.gov (United States)

    Costa, Christopher; Bradu, Adrian; Rogers, John; Phelan, Pauline; Podoleanu, Adrian

    2015-01-01

    We present a swept source optical coherence tomography (OCT) system at 1060 nm equipped with a wavefront sensor at 830 nm and a deformable mirror in a closed-loop adaptive optics (AO) system. Due to the AO correction, the confocal profile of the interface optics becomes narrower than the OCT axial range, restricting the part of the B-scan (cross section) with good contrast. By actuating on the deformable mirror, the depth of the focus is changed and the system is used to demonstrate Gabor filtering in order to produce B-scan OCT images with enhanced sensitivity throughout the axial range from a Drosophila larvae. The focus adjustment is achieved by manipulating the curvature of the deformable mirror between two user-defined limits. Particularities of controlling the focus for Gabor filtering using the deformable mirror are presented.

  16. Mirroring

    DEFF Research Database (Denmark)

    Wegener, Gregers

    2016-01-01

    and metaphorical value of mirroring for creativity theory across two different research fields — neuroscience and learning. We engage in a mutual (possibly creative) exploration of mirroring from ‘mirror neurons’ to mirroring in social learning theory. One of the most fascinating aspects of mirroring......Most definitions of creativity emphasise originality. The creative product is recognised as distinct from other products and the creative person as someone who stands out from the crowd. What tend to be overlooked are acts of mirroring as a crucial element of the creative process. The human ability...... to empathise and socialise is partly due to another, more fundamental ability to duplicate the stance of the other (see also Chapter 13). Through mirroring, we attune to other people and thus create resonance and preparedness for mutual creative exploration. In this chapter, we investigate the object...

  17. Real-time characterization of the spatio-temporal dynamics of deformable mirrors

    Science.gov (United States)

    Kilpatrick, James; Apostol, Adela; Khizhnya, Anatoliy; Markov, Vladimir; Beresnev, Leonid

    2016-09-01

    Innovative technologies are needed to support and augment the development of various types of deformable mirrors (DM), such as Micro Electro Mechanical Systems (MEMS), segmented, bimorph and membrane types that are currently used in adaptive-optic (AO) systems. The paper discusses the results of initial studies that, could, potentially, be employed for full characterization of the dynamic behavior of adaptive optics mirrors. The experimental data were obtained from a typical bimorph mirror using both, a Shack-Hartman wavefront sensor (SHWFS) and an Imaging Laser Doppler Vibrometer (ILDV) developed exclusively by AS and T Inc. These two sensors were employed for quantitative measurement of both the spatial and temporal dynamics of the DM under broadband excitation via the piezo electric drive elements. The need to characterize the spatial and temporal dynamic response of current and future DM mirror designs is essential for optimizing their performance to a level adequate for high bandwidth AO systems, such as those employed for real-time compensation of wavefront perturbations.

  18. Calibration strategy of the pyramid wavefront sensor module of ERIS with the VLT deformable secondary mirror

    Science.gov (United States)

    Riccardi, A.; Briguglio, R.; Pinna, E.; Agapito, G.; Quiros-Pacheco, F.; Esposito, S.

    2012-07-01

    ERIS is a new Adaptive Optics Instrument for the Adaptive Optics Facility of the VLT that foresees, in its design phase, a Pyramid Wavefront Sensor Module (PWM) to be used with the VLT Deformable Secondary Mirror (VLT-DSM) as corrector. As opposite to the concave secondary mirrors currently in use (e.g. at LBT), VLT-DSM is convex and calibration of the interaction matrix (IM) between the PWM and the DSM is not foreseen on-telescope during day-time. In this paper different options of calibration are evaluated and compared with particular attention on the synthetic evaluation and on-sky calibration of the IM. A trade-off of the calibration options, the optimization techniques and the related validation with numerical simulations are also provided.

  19. Integration of Micro-Electro-Mechanical Deformable Mirrors in Doped Fiber Amplifiers

    CERN Document Server

    Bouyge, D; Crunteanu, A; Blondy, P; Couderc, V; Lhermite, J; Grossard, L; Barthélemy, A

    2007-01-01

    We present a simple technique to produce active Q-switching in various types of fiber amplifiers by active integration of an electrostatic actuated deformable metallic micro-mirror. The optical MEMS (MOEMS) device acts as one of the laser cavity reflectors and, at the same time, as switching/ modulator element. We aim to obtain laser systems emitting short, high-power pulses and having variable repetition rate. The electro-mechanical behavior of membrane (bridge-type) was simulated by using electrostatic and modal 3D finite element analysis (FEA). The results of the simulations fit well with the experimental mechanical, electrical and thermal measurements of the components. In order to decrease the sensitiveness to fiber-mirror alignment we are developing novel optical devices based on stressed-metal cantilever-type geometry that allow deflections up to 50 $\\mu$m with increased reflectivity discrimination during actuation.

  20. Mathematical and computational modeling of a ferrofluid deformable mirror for high-contrast imaging

    Science.gov (United States)

    Lemmer, Aaron J.; Griffiths, Ian M.; Groff, Tyler D.; Rousing, Andreas W.; Kasdin, N. Jeremy

    2016-07-01

    Deformable mirrors (DMs) are an enabling and mission-critical technology in any coronagraphic instrument designed to directly image exoplanets. A new ferro fluid deformable mirror technology for high-contrast imaging is currently under development at Princeton, featuring a flexible optical surface manipulated by the local electromagnetic and global hydraulic actuation of a reservoir of ferro fluid. The ferro fluid DM is designed to prioritize high optical surface quality, high-precision/low-stroke actuation, and excellent low-spatial-frequency performance - capabilities that meet the unique demands of high-contrast coronagraphy in a space-based platform. To this end, the ferro-fluid medium continuously supports the DM face sheet, a configuration that eliminates actuator print-through (or, quilting) by decoupling the nominal surface figure from the geometry of the actuator array. The global pressure control allows independent focus actuation. In this paper we describe an analytical model for the quasi-static deformation response of the DM face sheet to both magnetic and pressure actuation. These modeling efforts serve to identify the key design parameters and quantify their contributions to the DM response, model the relationship between actuation commands and DM surface-profile response, and predict performance metrics such as achievable spatial resolution and stroke precision for specific actuator configurations. Our theoretical approach addresses the complexity of the boundary conditions associated with mechanical mounting of the face sheet, and makes use of asymptotic approximations by leveraging the three distinct length scales in the problem - namely, the low-stroke ( nm) actuation, face sheet thickness ( mm), and mirror diameter (cm). In addition to describing the theoretical treatment, we report the progress of computational multi physics simulations which will be useful in improving the model fidelity and in drawing conclusions to improve the design.

  1. The use of a high-order MEMS deformable mirror in the Gemini Planet Imager

    Energy Technology Data Exchange (ETDEWEB)

    Poyneer, L A; Bauman, B; Cornelissen, S; Jones, S; Macintosh, B; Palmer, D; Isaacs, J

    2010-12-17

    We briefly review the development history of the Gemini Planet Imager's 4K Boston Micromachines MEMS deformable mirror. We discuss essential calibration steps and algorithms to control the MEMS with nanometer precision, including voltage-phase calibration and influence function characterization. We discuss the integration of the MEMS into GPI's Adaptive Optics system at Lawrence Livermore and present experimental results of 1.5 kHz closed-loop control. We detail mitigation strategies in the coronagraph to reduce the impact of abnormal actuators on final image contrast.

  2. High-precision system identification method for a deformable mirror in wavefront control.

    Science.gov (United States)

    Huang, Lei; Ma, Xingkun; Bian, Qi; Li, Tenghao; Zhou, Chenlu; Gong, Mali

    2015-05-10

    Based on a mathematic model, the relation between the accuracy of the influence matrix and the performance of the wavefront correction is established. Based on the least squares method, a two-step system identification is proposed to improve the accuracy of the influence matrix, where the measurement noise can be suppressed and the nonlinearity of the deformable mirror can be compensated. The validity of the two-step system identification method is tested in the experiment, where improvements in wavefront correction precision as well as closed-loop control efficiency were observed.

  3. Sub-nanometer flattening of 45 cm long, 45 actuator x-ray deformable mirror.

    Science.gov (United States)

    Poyneer, Lisa A; McCarville, Thomas; Pardini, Tommaso; Palmer, David; Brooks, Audrey; Pivovaroff, Michael J; Macintosh, Bruce

    2014-06-01

    We have built a 45 cm long x-ray deformable mirror (XDM) of super-polished single-crystal silicon that has 45 actuators along the tangential axis. After assembly, the surface height error was 19 nm rms. With use of high-precision visible-light metrology and precise control algorithms, we have actuated the XDM and flattened its entire surface to 0.7 nm rms controllable figure error. This is, to our knowledge, the first sub-nanometer active flattening of a substrate longer than 15 cm.

  4. Self-Tuning Mechanism for the Design of Adaptive Secondary Mirror Position Control

    NARCIS (Netherlands)

    Battistelli, Giorgio; Mari, Daniele; Riccardi, Armando; Tesi, Pietro

    2015-01-01

    Deformable mirrors (DMs) are electromechanical devices used in ground-based telescopes to compensate for the distortions caused by the atmospheric turbulence, the main factor limiting the resolution of astronomical imaging. Adaptive secondary mirrors (ASMs) represent a new type of DMs; two of them

  5. Stability of the micromachined membrane deformable mirror as a freeform optical element

    Science.gov (United States)

    Vdovin, Gleb; Soloviev, Oleg; Patlan, Seva

    2014-09-01

    Micromachined membrane deformable mirror (MMDM) can serve as an ad hoc" free-form optical element. To test the repeatability and stability of the standard MMDM, we have conducted the test of surface figure during multiple thermal cycling, test of figure drift at elevated temperatures, and a long-term 16-day stability test of actively formed mirror figure. The average rms error did not exceed λ =25 at λ = 633 nm, after repeated cycling from -14 to +70 C, with return to the room temperature. The existing design provides ~10° stability in the temperature range of ~10°. Optimization of the design, eliminating astigmatism, would allow one to extend the temperature range to about 30. The long-term mirror figure instability at a constant temperature reaches λ/20 rms in 16 days. The P-V error with respect to the nearest sphere changes from λ/20 in the first day, to about λ/10 in the 16-th day. The tests show that MMDM is stable enough to make a reasonable alternative to free-form optics in applications that require various optical shapes to be formed with a single element.

  6. Digital holographic interferometry for characterizing deformable mirrors in aero-optics

    Science.gov (United States)

    Trolinger, James D.; Hess, Cecil F.; Razavi, Payam; Furlong, Cosme

    2016-08-01

    Measuring and understanding the transient behavior of a surface with high spatial and temporal resolution are required in many areas of science. This paper describes the development and application of a high-speed, high-dynamic range, digital holographic interferometer for high-speed surface contouring with fractional wavelength precision and high-spatial resolution. The specific application under investigation here is to characterize deformable mirrors (DM) employed in aero-optics. The developed instrument was shown capable of contouring a deformable mirror with extremely high-resolution at frequencies exceeding 40 kHz. We demonstrated two different procedures for characterizing the mechanical response of a surface to a wide variety of input forces, one that employs a high-speed digital camera and a second that employs a low-speed, low-cost digital camera. The latter is achieved by cycling the DM actuators with a step input, producing a transient that typically lasts up to a millisecond before reaching equilibrium. Recordings are made at increasing times after the DM initiation from zero to equilibrium to analyze the transient. Because the wave functions are stored and reconstructable, they can be compared with each other to produce contours including absolute, difference, and velocity. High-speed digital cameras recorded the wave functions during a single transient at rates exceeding 40 kHz. We concluded that either method is fully capable of characterizing a typical DM to the extent required by aero-optical engineers.

  7. Feasible optimal deformable mirror shaping algorithm for high-contrast imaging

    Science.gov (United States)

    Give'on, Amir; Kasdin, N. Jeremy; Vanderbei, Robert J.; Spergel, David N.; Littman, Michael G.; Gurfil, Pini

    2003-12-01

    The Princeton University Terrestrial Planet Finder (TPF) group has been working on a novel method for direct imaging of extra solar planets using a shaped-pupil coronagraph. The entrance pupil of the coronagraph is optimized to have a point spread function (PSF) that provides the suppression level needed at the angular separation required for detection of extra solar planets. When integration time is to be minimized, the photon count at the planet location in the image plane is a Poisson distributed random process. The ultimate limitation of these high-dynamic-range imaging systems comes from scattering due to imperfections in the optical surfaces of the collecting system. The first step in correcting the wavefront errors is the estimation of the phase aberrations. The phase aberration caused by these imperfections is assumed to be a sum of two-dimensional sinusoidal functions. Assuming one uses a deformable mirror to correct these aberrations, we propose an algorithm that optimally decreases the scattering level in specified localized areas in the image plane independent of the choice of influence function of the deformable mirror.

  8. Wave-front correction of femtosecond terawatt lasers by deformable mirrors.

    Science.gov (United States)

    Druon, F; Chériaux, G; Faure, J; Nees, J; Nantel, M; Maksimchuk, A; Mourou, G; Chanteloup, J C; Vdovin, G

    1998-07-01

    Wave-front correction and focal spot improvement of femtosecond laser beams have been achieved, for the first time to our knowledge, with a deformable mirror with an on-line single-shot three-wave lateral shearing interferometer diagnostic. Wave-front distortions of a 100-fs laser that are due to third-order nonlinear effects have been compensated for. This technique, which permits correction in a straightforward process that requires no feedback loop, is also used on a 10-TW Ti:sapphire-Nd:phosphate glass laser in the subpicosecond regime. We also demonstrate that having a focal spot close to the diffraction limit does not constitute a good criterion for the quality of the laser in terms of peak intensity.

  9. 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.

  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. A 45-element continuous facesheet surface micromachined deformable mirror for optical aberration correction

    Directory of Open Access Journals (Sweden)

    Weimin Wang

    2014-02-01

    Full Text Available A 45-element continuous facesheet surface micromachined deformable mirror (DM is presented and is fabricated using the PolyMUMPs multi-user micro-electro-mechanical system processes. The effects of the structural parameters on the characteristics of the DM, such as its stroke, frequency and actuator coupling, are analyzed. In addition, the DM design has also been verified through experimental testing. This DM prototype has a surface figure of 0.5 μm and a fill factor of 95%. The DM can provide a 0.6 μm stroke with 5.9% actuator coupling. A static aberration correction based on this DM is also demonstrated, which acts as a reference for the potential adaptive optics (AO applications of the device.

  12. Optimization with numerical simulations of the conjugate altitudes of deformable mirrors in an MCAO system

    CERN Document Server

    Femenia, B

    2003-01-01

    This article reports on the results of simulations conducted to assess the performance of a modal Multi-Conjugate Adaptive Optics (MCAO) system on a 10m telescope with one Deformable Mirror (DM) conjugated to the telescope pupil and a second DM conjugated at a certain altitude above the pupil. The main goal of these simulations is to study the dependence of MCAO performance upon the altitude of the high-altitude conjugated DM and thereby determine its optimal conjugation. The performance is also studied with respect to the geometry of the Guide Star constellation when using constellations of Natural Guide Stars (NGS), which are rare, or constellations of Laser Guide Stars (LGS) which would allow large sky coverage.

  13. Wave front adaptation using a deformable mirror for adiabatic nanofocusing along an ultrasharp gold taper.

    Science.gov (United States)

    Schmidt, Slawa; Engelke, Pascal; Piglosiewicz, Björn; Esmann, Martin; Becker, Simon F; Yoo, Kyungwan; Park, Namkyoo; Lienau, Christoph; Groß, Petra

    2013-11-01

    We describe and demonstrate the use of an adaptive wave front optimization scheme for enhancing the efficiency of adiabatic nanofocusing of surface plasmon polariton (SPP) waves along an ultrasharp conical gold taper. Adiabatic nanofocusing is an emerging and promising scheme for controlled focusing of far field light into nanometric volumes. It comprises three essential steps: SPP excitation by coupling far field light to an SPP waveguide, SPP propagation along the waveguide and adiabatic SPP nanofocusing towards a geometric singularity. For commonly used complex waveguide geometries, such as, e.g., conical metal tapers, a realistic modeling and efficiency optimization is challenging. Here, we use a deformable mirror to adaptively control the wave front of the incident far field light. We demonstrate an eight-fold enhancement in nanofocusing efficiency and analyze the shape of the resulting optimized wave front. The introduced wave front optimization scheme is of general interest for guiding and controlling light on the nanoscale.

  14. X-ray metrology and performance of a 45-cm long x-ray deformable mirror.

    Science.gov (United States)

    Poyneer, Lisa A; Brejnholt, Nicolai F; Hill, Randall; Jackson, Jessie; Hagler, Lisle; Celestre, Richard; Feng, Jun

    2016-05-01

    We describe experiments with a 45-cm long x-ray deformable mirror (XDM) that have been conducted in End Station 2, Beamline 5.3.1 at the Advanced Light Source. A detailed description of the hardware implementation is provided. We explain our one-dimensional Fresnel propagation code that correctly handles grazing incidence and includes a model of the XDM. This code is used to simulate and verify experimental results. Initial long trace profiler metrology of the XDM at 7.5 keV is presented. The ability to measure a large (150-nm amplitude) height change on the XDM is demonstrated. The results agree well with the simulated experiment at an error level of 1 μrad RMS. Direct imaging of the x-ray beam also shows the expected change in intensity profile at the detector.

  15. Experience with wavefront sensor and deformable mirror interfaces for wide-field adaptive optics systems

    Science.gov (United States)

    Basden, A. G.; Atkinson, D.; 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.; Le Roux, B.; 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.; Sanchez Lasheras, F.; Sanchez Rodriguez, M.; Santos, J. D.; Sevin, A.; Sivo, G.; Stadler, E.; Stobie, B.; Talbot, G.; Todd, S.; Vidal, F.; Younger, E. J.

    2016-06-01

    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 AO 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.

  16. Thermal stability test and analysis of a 20-actuator bimorph deformable mirror

    Institute of Scientific and Technical Information of China (English)

    Ning Yu; Zhou Hong; Yu Hao; Rao Chang-Hui; Jiang Wen-Han

    2009-01-01

    One of the important characteristic of adaptive mirrors is the thermal stability of surface flatness. In this paper, the thermal stability from 13℃ to 25℃ of a 20-actuator bimorph deformable mirror is tested by a Shack-Hartmann wavefront sensor. Experimental results show that, the surface P-V of bimorph increases nearly linearly with ambient temperature. The ratio is 0.11 μm/℃ and the major component of surface displacement is defocused, compared with which, astigmatism, coma and spherical aberration contribute very small. Besides, a finite element model is built up to analyse the influence of thickness, thermal expansion coefficient and Young's modulus of materials on thermal stability. Calculated results show that bimorph has the best thermal stability when the materials have the same thermal expansion coefficient. And when the thickness ratio of glass to PZT is 3 and Young's modulus ratio is approximately 0.4, the surface instability behaviour of the bimorph manifests itself most severely.

  17. Principles And Design Of Multibeam Interference Devices: A Microelectromechanical-Systems Segment-Deformable-Mirror-Based Adaptive Spectrum Attenuator

    OpenAIRE

    Huang, Z.Y.; Zhu, Y. Z.; Wang, Anbo

    2005-01-01

    Fourier analysis of multibeam interference shows that the total electric field and relative time delay of the beams form a Fourier-transform pair. Fourier-analysis-based multibeam interference analysis and device design is discussed in detail. The principle of the proposed segment-deformable-mirror-based adaptive spectrum attenuator is illustrated. (c) 2005 Optical Society of America.

  18. Experimental study and analytical model of deformation of magnetostrictive films as applied to mirrors for x-ray space telescopes.

    Science.gov (United States)

    Wang, Xiaoli; Knapp, Peter; Vaynman, S; Graham, M E; Cao, Jian; Ulmer, M P

    2014-09-20

    The desire for continuously gaining new knowledge in astronomy has pushed the frontier of engineering methods to deliver lighter, thinner, higher quality mirrors at an affordable cost for use in an x-ray observatory. To address these needs, we have been investigating the application of magnetic smart materials (MSMs) deposited as a thin film on mirror substrates. MSMs have some interesting properties that make the application of MSMs to mirror substrates a promising solution for making the next generation of x-ray telescopes. Due to the ability to hold a shape with an impressed permanent magnetic field, MSMs have the potential to be the method used to make light weight, affordable x-ray telescope mirrors. This paper presents the experimental setup for measuring the deformation of the magnetostrictive bimorph specimens under an applied magnetic field, and the analytical and numerical analysis of the deformation. As a first step in the development of tools to predict deflections, we deposited Terfenol-D on the glass substrates. We then made measurements that were compared with the results from the analytical and numerical analysis. The surface profiles of thin-film specimens were measured under an external magnetic field with white light interferometry (WLI). The analytical model provides good predictions of film deformation behavior under various magnetic field strengths. This work establishes a solid foundation for further research to analyze the full three-dimensional deformation behavior of magnetostrictive thin films.

  19. Intracavity control of a 200-W continuous-wave Nd:YAG laser by a micromachined deformable mirror.

    Science.gov (United States)

    Vdovin, G; Kiyko, V

    2001-06-01

    A silicon micromachined membrane deformable mirror with a diameter of 10 mm, reflectivity of better than 99.8%, and a surface deflection range of 3mum has been used for intracavity control of an industrial 200-W cw Nd:YAG laser. When it was placed in the resonator, the mirror demonstrated continuous (more than 40-h) stable operation under an ~550-W cw optical load, with beam diameters in the range 3-6 mm. Periodic modulation of the curvature of the deformable mirror with a frequency of 250 Hz produced quick switching between stable and unstable resonator configurations, which resulted in pulse-period Q -switched generation with average power in the range 50-200 W, modulation depth from 95% to 10%, and an M(2) parameter of 6.5 to 30.

  20. Long-term stability and temperature variability of Iris AO segmented MEMS deformable mirrors

    CERN Document Server

    Helmbrecht, M A; Kempf, C J; Marchis, F

    2016-01-01

    Long-term stability of deformable mirrors (DM) is a critical performance requirement for instruments requiring open-loop corrections. The effects of temperature changes in the DM performance are equally critical for such instruments. This paper investigates the long-term stability of three different Iris AO PTT111 DMs that were calibrated at different times ranging from 13 months to nearly 29 months prior to subsequent testing. Performance testing showed that only a small increase in positioning errors occurred from the initial calibration date to the test dates. The increases in errors ranged from as little as 1.38 nm rms after 18 months to 5.68 nm rms after 29 months. The paper also studies the effects of small temperature changes, up to 6.2{\\deg}C around room temperature. For three different arrays, the errors ranged from 0.62-1.42 nm rms/{\\deg}C. Removing the effects of packaging shows that errors are $\\le$0.50 nm rms/{\\deg}C. Finally, measured data showed that individual segments deformed $\\le$0.11 nm rm...

  1. Modified deformable mirror stroke minimization control for direct imaging of exoplanets

    Science.gov (United States)

    Sun, He; Eldorado Riggs, A. J.; Kasdin, N. Jeremy; Vanderbei, Robert; Groff, Tyler

    2016-08-01

    For direct imaging of faint exoplanets, coronagraphs are widely used to suppress light and achieve a high contrast. Wavefront correction algorithms based on adaptive optics are introduced simultaneously to mitigate aberrations in the optical system. Stroke minimization is one of the primary control algorithms used for high-contrast wavefront control. This technique calculates the minimum deformation across the deformable mirrors' surface under the constraint that a targeted average contrast level in the search areas, namely the dark holes, is achieved. In this paper we present a modified linear constraint stroke minimization algorithm. Instead of using a single constraint on intensity averaged over all pixels, we constrain the electric field's real and imaginary part of each pixel in the dark holes. The new control algorithm can be written into a linear programming problem. Model reduction methods, including pixel binning and singular value decomposition (SVD), are further employed to avoid over-constraining the problem and to speed up computation. In numerical simulation, we find that the revised algorithm leads to more uniform dark holes and faster convergence.

  2. A new driving method for piezo deformable mirrors: open loop control and MOAO made easy

    Science.gov (United States)

    Ouattara, Issa; Gach, Jean-Luc; Amram, Philippe

    2016-07-01

    This paper presents the design and the realisation of a technique to attenuate the hysteresis nonlinear phenomenon of piezoelectric actuators. Piezoelectric actuator are widely utilised for deformable mirrors used for MOAO and power laser beam shaping techniques. The nonlinearities of piezo are usually iteratively compensa- ted using closed-loop set-ups. In open-loop control, the hysteresis and the creep of the piezo cannot be corrected, thus this nonlinearities must be removed or at least minimised. The concept has been demonstrated on high displacement Amplified Piezoelectric Actuators (APA) mounted in a Fabry-Perot interferometer. The hysteresis attenuation technique aims to assist the Fabry-Perots nano-positioning control system to attain its main scientific specification. In such system, each APA has a maximum stroke of 270 μm within a 170 V (-20 V to +150 V) range and is used to position a high reflective mirror plate. The Fabry-Perots nano-positioning control system is specified to limit the APAs positioning steady-state noise to 3nm rms, but the hysteresis limits the positioning accuracy. In order to attenuate hysteresis, a hybrid amplifier circuit built with a high power operational amplifier has been designed and applied for each APA. The experiments results show that the hysteresis effect has almost been eliminated, and consequently the positioning steady-state noise can significantly been reduced. Because of the excellent results of this hybrid amplifier, a patent application has been introduced in June 12, 2015 under number No.1555381 and is being reviewed now.

  3. Long-term stability and temperature variability of Iris AO segmented MEMS deformable mirrors

    Science.gov (United States)

    Helmbrecht, M. A.; He, M.; Kempf, C. J.; Marchis, F.

    2016-07-01

    Long-term stability of deformable mirrors (DM) is a critical performance requirement for instruments requiring open-loop corrections. The effects of temperature changes in the DM performance are equally critical for such instruments. This paper investigates the long-term stability of three different Iris AO PTT111 DMs that were calibrated at different times ranging from 13 months to nearly 29 months prior to subsequent testing. Performance testing showed that only a small increase in positioning errors occurred from the initial calibration date to the test dates. The increases in errors ranged from as little as 1.38 nm rms after 18 months to 5.68 nm rms after 29 months. The paper also studies the effects of small temperature changes, up to 6.2°C around room temperature. For three different arrays, the errors ranged from 0.62-1.42 nm rms/°C. Removing the effects of packaging shows that errors are heated.

  4. Preparation and Characterization of Silver Liquid Thin Films for Magnetic Fluid Deformable Mirror

    Directory of Open Access Journals (Sweden)

    Lianchao Zhang

    2015-01-01

    Full Text Available Silver liquid thin film, formed by silver nanoparticles stacking and spreading on the surface of the liquid, is one of the important parts of magnetic fluid deformable mirror. First, silver nanoparticles were prepared by liquid phase chemical reduction method using sodium citrate as reducing agent and stabilizer and silver nitrate as precursor. Characterization of silver nanoparticles was studied using X-ray diffractometer, UV-vis spectrophotometer, and transmission electron microscope (TEM. The results showed that silver nanoparticles are spherical and have a good monodispersity. Additionally, the effect of the reaction conditions on the particle size of silver is obvious. And then silver liquid thin films were prepared by oil-water two-phase interface technology using as-synthesized silver nanoparticles. Properties of the film were investigated using different technology. The results showed that the film has good reflectivity and the particle size has a great influence on the reflectivity of the films. SEM photos showed that the liquid film is composed of multilayer silver nanoparticles. In addition, stability of the film was studied. The results showed that after being stored for 8 days under natural conditions, the gloss and reflectivity of the film start to decrease.

  5. Enhancing ablation efficiency in micro structuring using a deformable mirror for beam shaping of ultra-short laser pulses

    Science.gov (United States)

    Smarra, M.; Dickmann, K.

    2016-03-01

    Using ultra-short laser pulses for the generation of microstructures results in a high flexible tool for free form geometries in the micro range. Increasing laser power and repetition rates increase as well the demand of high flexible and efficient process strategies. To increase the ablation efficiency the optimal fluency can be determined, which is a material specific value. By varying the beam shape, the ablation efficiency can be enhanced. In this study a deformable mirror was used to vary the beam shape. This mirror is built by combining a piezo-electric ceramic and a mirror substrate. The ceramic is divided into several segments, which can be controlled independently. This results in a high flexible deformable mirror which influences the beam shape and can be used to vary the spot size or generate line geometries. The ablation efficiency and roughness of small generated cavities were analyzed in this study as well as the dimensions of the cavity. This can be used to optimize process strategies to combine high volume ablation and fine detail generation.

  6. Optical Correction Of Space-Based Telescopes Using A Deformable Mirror System

    Science.gov (United States)

    2016-12-01

    Experimental work first studied a severely degraded one-meter carbon fiber reinforced polymer mirror to establish a baseline. Simulations were...telescope. Experimental work first studied a severely degraded one-meter carbon fiber reinforced polymer mirror to establish a baseline. Simulations... INTRODUCTION ..................................................................................................1  A.  PURPOSE

  7. Characterising x-ray mirror deformations with a phase measuring deflectometry system

    Science.gov (United States)

    Breunig, E.; Friedrich, P.; Proserpio, L.; Winter, A.

    2014-07-01

    MPE is developing modular x-ray mirrors for the next generation of high-energy astronomy missions. The mirror segments are based on thermally formed (a.k.a. slumped) glass sheets, with a typical thickness of 400µm. One of the major challenges is the alignment and integration of the mirror segments and the associated metrology. The optical performance of the mirror can be significantly compromised by adhesive shrinkage, gravity sag or residual stresses influenced by the properties of the mirror mounting and the integration procedure. In parallel with classic coordinate measurement techniques we utilize a deflectometry based metrology system to characterization shape errors of the mirror surfaces. A typical deflectometry setup uses a TFT display to project a sinusoidal pattern onto a specular test surface (SUT) and a camera that observes the reflected image. This reflected image contains slope information of the SUT in the form of distortions of the original displayed pattern. A phase shifting technique can be used to recover this slope information with only very few exposures and reasonable computational effort. The deflectometry system enables us to characterize bonding interfaces of slumped glass mirrors, as well as influence of temporary mounting points, handling and thermal distortions. It is also well suited to measure transient effects.

  8. Enhanced Fabrication Processes Development for High Actuator Count Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to design and fabricate a MEMS micromirror array consisting of 1021 ultra-flat, close-packed hexagonal mirror elements, each capable of 6mrad of tip and...

  9. Development of a Lightweight Segmented Deformable Mirror for High-Order Wavefront Control

    Science.gov (United States)

    Bastaits, R.; Alaluf, D.; Horodinca, M.; Romanescu, I.; Burda, I.; Martic, G.; Preumont, A.

    2014-06-01

    This paper discusses a concept of light weight segmented bimorph mirror for adaptive optics. The first part of the paper discusses the morphing strategy and addresses the ill-conditioning of the Jacobian of the segments which are partly outside the optical pupil. A comparison of various configurations of segmented mirrors is conducted; it is shown that segmentation increases sharply the natural frequency of the system with a limited deterioration of the image quality. The second part of the paper discusses a few technological aspects of the segment design which are critical for space applications, describes a single segment demonstrator and reports on open loop shape control experimental results.

  10. Coupling of a CMOS Optical Sensor to a Micromachined Deformable Mirror with an Adaline Neural Method

    NARCIS (Netherlands)

    De Lima Monteiro, D.W.; Ferreira, A.I.; Teixeira, F.B.; Melo, J.G.M.; Vdovin, G.V.

    2006-01-01

    We report on the preliminary results of an Adaline neural method for the coupling of a custom CMOS wavefront sensor to a micromachined adaptive mirror. The algorithm does not rely on a fixed basis matrix -as opposed to traditional methods-, offers excellent immunity to round-off errors and admits re

  11. Coupling of a CMOS Optical Sensor to a Micromachined Deformable Mirror with an Adaline Neural Method

    NARCIS (Netherlands)

    De Lima Monteiro, D.W.; Ferreira, A.I.; Teixeira, F.B.; Melo, J.G.M.; Vdovin, G.V.

    2006-01-01

    We report on the preliminary results of an Adaline neural method for the coupling of a custom CMOS wavefront sensor to a micromachined adaptive mirror. The algorithm does not rely on a fixed basis matrix -as opposed to traditional methods-, offers excellent immunity to round-off errors and admits re

  12. Correcting Surface Figure Error in Imaging Satellites Using a Deformable Mirror

    Science.gov (United States)

    2013-12-01

    phrase, “Going to the lab—be back in a while.” xvi THIS PAGE INTENTIONALLY LEFT BLANK 1 I. INTRODUCTION The Intelligence Community (IC...this thesis is to provide a proof-of-concept for an integral component that would serve as a mirror surface figure corrector to enable the ultimate...included in the DM sub-assembly to eliminate unwanted back reflections. A ¼ wave-plate is used after the interferometer to convert circularly

  13. Modeling of a Micro-Electronic Mechanical Systems (MEMS) Deformable Mirror for Simulation and Characterization

    Science.gov (United States)

    2016-09-01

    25  B.  MODEL USER APPLICABILITY ........................................................29  V.  CONCLUSION AND FUTURE WORK...this research, as it is the most complex mirror type. This device is composed of two mechanical systems: an array of actuations and a non- linear ...3.5) Equation (3.5) can be adapted into an algebraic expression in order to solve for the plate

  14. Design of a Compact, Bimorph Deformable Mirror-Based Adaptive Optics Scanning Laser Ophthalmoscope.

    Science.gov (United States)

    He, Yi; Deng, Guohua; Wei, Ling; Li, Xiqi; Yang, Jinsheng; Shi, Guohua; Zhang, Yudong

    2016-01-01

    We have designed, constructed and tested an adaptive optics scanning laser ophthalmoscope (AOSLO) using a bimorph mirror. The simulated AOSLO system achieves diffraction-limited criterion through all the raster scanning fields (6.4 mm pupil, 3° × 3° on pupil). The bimorph mirror-based AOSLO corrected ocular aberrations in model eyes to less than 0.1 μm RMS wavefront error with a closed-loop bandwidth of a few Hz. Facilitated with a bimorph mirror at a stroke of ±15 μm with 35 elements and an aperture of 20 mm, the new AOSLO system has a size only half that of the first-generation AOSLO system. The significant increase in stroke allows for large ocular aberrations such as defocus in the range of ±600° and astigmatism in the range of ±200°, thereby fully exploiting the AO correcting capabilities for diseased human eyes in the future.

  15. Pair-Wise, Deformable Mirror, Image Plane-Based Diversity Electric Field Estimation for High Contrast Coronagraphy

    Science.gov (United States)

    Give'on, Amir; Kern, Brian D.; Shaklan, Stuart

    2011-01-01

    In this paper we describe the complex electric field reconstruction from image plane intensity measurements for high contrast coronagraphic imaging. A deformable mirror (DM) surface is modied with pairs of complementary shapes to create diversity in the image plane of the science camera where the intensity of the light is measured. Along with the Electric Field Conjugation correction algorithm, this estimation method has been used in various high contrast imaging testbeds to achieve the best contrasts to date both in narrow and in broad band light. We present the basic methodology of estimation in easy to follow list of steps, present results from HCIT and raise several open quations we are confronted with using this method.

  16. Monte-Carlo simulation of ELT scale multi-object adaptive optics deformable mirror requirements and tolerances

    CERN Document Server

    Basden, A G; Myers, R M; Morris, S L; Morris, T J

    2013-01-01

    Multi-object adaptive optics (MOAO) has been demonstrated by the CANARY instrument on the William Herschel Telescope. However, for proposed MOAO systems on the next generation Extremely Large Telescopes, such as EAGLE, many challenges remain. Here we investigate requirements that MOAO operation places on deformable mirrors (DMs) using a full end-to-end Monte-Carlo AO simulation code. By taking into consideration a prior global ground-layer (GL) correction, we show that actuator density for the MOAO DMs can be reduced with little performance loss. We note that this reduction is only possible with the addition of a GL DM, whose order is greater than or equal to that of the original MOAO mirrors. The addition of a GL DM of lesser order does not affect system performance (if tip/tilt star sharpening is ignored). We also quantify the maximum mechanical DM stroke requirements (3.5 $\\mu$m desired) and provide tolerances for the DM alignment accuracy, both lateral (to within an eighth of a sub-aperture) and rotationa...

  17. Modelling and optimization of a deformable mirror for laser beam control

    CSIR Research Space (South Africa)

    Loveday, PW

    2008-03-01

    Full Text Available -6 Normalised radius Di sp la c em en t [m ] Rayleigh-Ritz R-Dof Comsol (a) Vdrive=[200:0:0]. (b) Vdrive=[0:200:0]. (c) Vdrive=[0:0:200]. Figure 6. Comparison of mirror surface displacement prediction using different numerical models.... When a voltage is applied to the piezoelectric disc the induced strains in the plane of the disc cause bending of the unimorph. In this way relatively large displacements, compared to the 10.6 µm wavelength of a CO2 laser, can be obtained from a...

  18. Fault-tolerant drive electronics for a Xinetics deformable mirror at GeMS DM0

    Science.gov (United States)

    Barberio, Michael J.

    2016-07-01

    Gemini South is replacing one of the (3) CILAS DMs with a 349-actuator Xinetics DM in its GeMS MCAO system. Xinetics mirrors operate over a 40-100V dynamic range and require that inter-actuator stroke differences are limited to half-scale; each actuator must be within 30V of its neighbor to prevent mechanical stress and possible face sheet separation. A robust way to implement this protection is to use high power transient voltage suppressors (TVSs) as a 2D-mesh between the amplifiers and mirror, but this has system implications. A sustained clamp condition dissipates significant power in the devices, and if an actuator fails as short (which occurred once with the DM in a thermal chamber), the system is subject to a cascade failure event as multiple outputs drive the shorted actuator through the TVS network. This latter risk is readily resolved by using series fuses to the DM. In this third-generation driver, current sensing and logic inhibit amplifier outputs after a sustained TVS clamp condition or shorted output, and LED indicators show the location. Redundant thermal sensing is used on modular TVS row and column boards. A second 2D-mesh of high impedance resistors after the fuses will hold an unpowered channel to the average voltage of its neighbors, with a negligible influence function. A Failure Modes and Effects Analysis shows significant fault tolerance.

  19. Nearly diffraction-limited X-ray focusing with variable-numerical-aperture focusing optical system based on four deformable mirrors

    Science.gov (United States)

    Matsuyama, Satoshi; Nakamori, Hiroki; Goto, Takumi; Kimura, Takashi; Khakurel, Krishna P.; Kohmura, Yoshiki; Sano, Yasuhisa; Yabashi, Makina; Ishikawa, Tetsuya; Nishino, Yoshinori; Yamauchi, Kazuto

    2016-04-01

    Unlike the electrostatic and electromagnetic lenses used in electron microscopy, most X-ray focusing optical systems have fixed optical parameters with constant numerical apertures (NAs). This lack of adaptability has significantly limited application targets. In the research described herein, we developed a variable-NA X-ray focusing system based on four deformable mirrors, two sets of Kirkpatrick-Baez-type focusing mirrors, in order to control the focusing size while keeping the position of the focus unchanged. We applied a mirror deformation procedure using optical/X-ray metrology for offline/online adjustments. We performed a focusing test at a SPring-8 beamline and confirmed that the beam size varied from 108 nm to 560 nm (165 nm to 1434 nm) in the horizontal (vertical) direction by controlling the NA while maintaining diffraction-limited conditions.

  20. Nearly diffraction-limited X-ray focusing with variable-numerical-aperture focusing optical system based on four deformable mirrors.

    Science.gov (United States)

    Matsuyama, Satoshi; Nakamori, Hiroki; Goto, Takumi; Kimura, Takashi; Khakurel, Krishna P; Kohmura, Yoshiki; Sano, Yasuhisa; Yabashi, Makina; Ishikawa, Tetsuya; Nishino, Yoshinori; Yamauchi, Kazuto

    2016-04-21

    Unlike the electrostatic and electromagnetic lenses used in electron microscopy, most X-ray focusing optical systems have fixed optical parameters with constant numerical apertures (NAs). This lack of adaptability has significantly limited application targets. In the research described herein, we developed a variable-NA X-ray focusing system based on four deformable mirrors, two sets of Kirkpatrick-Baez-type focusing mirrors, in order to control the focusing size while keeping the position of the focus unchanged. We applied a mirror deformation procedure using optical/X-ray metrology for offline/online adjustments. We performed a focusing test at a SPring-8 beamline and confirmed that the beam size varied from 108 nm to 560 nm (165 nm to 1434 nm) in the horizontal (vertical) direction by controlling the NA while maintaining diffraction-limited conditions.

  1. 基于静电排斥力的大冲程MEMS变形镜%Large-Stroke MEMS Deformable Mirrors Based on Electrostatic-Repulsive-Force

    Institute of Scientific and Technical Information of China (English)

    陈科帆; 姚军; 高福华; 汪为民; 倪祖高

    2011-01-01

    A large-stroke electrostatic-repulsive-force MEMS deformable mirror was designed and fabricated. This deformable mirror was prepared using a surface-micromachining polysilicon process, and consisted of three polysilicon structural layers and a metal reflective layer. Three types of the mirrors with different actuator electrodes arrangements were investigated by finite element analysis, and measured with a scanning white light interferometer. The results show that the displacement of the electrostatic-repulsive-force deformable mirrors is more than 1.7 μm at 200 V, and the stroke of which is larger than that of conventional electrostatic-attractive-force deformable mirrors. Additionally, the deformable mirror has the largest stroke of 2.42 μm at 210 V with the third polysilicon layer as the fringe electrode.%设计并制造了一种基于静电排斥力的大冲程MEMS变形镜,此变形镜采用了三个多晶硅结构层和一个金属反射层的设计.利用表面硅工艺完成了变形镜的加工,结合有限元分析软件和白光干涉仪对三种不同驱动器电极空间分布方式的静电排斥型变形镜进行了分析和研究.测试结果表明,静电排斥型变形镜在200V下能实现1.7 μm以上的位移,冲程较传统静电吸引型变形镜有显著提高.在相同电压下,第三层多晶硅作为边缘电极时的变形镜获得的位移最大,在210 V下达到2.42 μm.

  2. Design and Fabrication of a Large-Stroke Deformable Mirror Using a Gear-Shape Ionic-Conductive Polymer Metal Composite

    Directory of Open Access Journals (Sweden)

    Guo-Dung John Su

    2012-08-01

    Full Text Available Conventional camera modules with image sensors manipulate the focus or zoom by moving lenses. Although motors, such as voice-coil motors, can move the lens sets precisely, large volume, high power consumption, and long moving time are critical issues for motor-type camera modules. A deformable mirror (DM provides a good opportunity to improve these issues. The DM is a reflective type optical component which can alter the optical power to focus the lights on the two dimensional optical image sensors. It can make the camera system operate rapidly. Ionic polymer metal composite (IPMC is a promising electro-actuated polymer material that can be used in micromachining devices because of its large deformation with low actuation voltage. We developed a convenient simulation model based on Young’s modulus and Poisson’s ratio. We divided an ion exchange polymer, also known as Nafion®, into two virtual layers in the simulation model: one was expansive and the other was contractive, caused by opposite constant surface forces on each surface of the elements. Therefore, the deformation for different IPMC shapes can be described more easily. A standard experiment of voltage vs. tip displacement was used to verify the proposed modeling. Finally, a gear shaped IPMC actuator was designed and tested. Optical power of the IPMC deformable mirror is experimentally demonstrated to be 17 diopters with two volts. The needed voltage was about two orders lower than conventional silicon deformable mirrors and about one order lower than the liquid lens.

  3. Effects of mirror distortion by thermal deformation in an interferometry beam size monitor system at PLS-II

    Science.gov (United States)

    Hwang, Ji-Gwang; Kim, Eun-San; Kim, Changbum; Huang, Jung-Yun; Kim, Dotae

    2016-10-01

    Extraction mirrors installed at the most upstream position of interferometry beam size monitor are frequently used for measuring the beam size in storage rings. These mirrors receive the high power synchrotron radiation and are distorted owing to the heat distribution that depends on the position on the mirror surface. The distortion of the mirror changes the effective separation of the slit in the interferometry beam size monitor. Estimation of the effects of the front-end mirror distortion is important for measuring the beam size accurately. In this paper, we present the result of the numerical simulation of the temperature distribution and thermal expansion of the front-end mirror using ANSYS code, the theoretical basis of the effects of mirror distortion and compare with experimental results from Pohang Light Source II (PLS-II) at the Pohang Accelerator Laboratory (PAL). The equipment in the beam diagnosis line in PLS-II and experimental set-up for measuring the distortion of the front-end mirror using a multi-hole square array Hartmann screen are described.

  4. Ground based materials science experiments

    Science.gov (United States)

    Meyer, M. B.; Johnston, J. C.; Glasgow, T. K.

    1988-01-01

    The facilities at the Microgravity Materials Science Laboratory (MMSL) at the Lewis Research Center, created to offer immediate and low-cost access to ground-based testing facilities for industrial, academic, and government researchers, are described. The equipment in the MMSL falls into three categories: (1) devices which emulate some aspect of low gravitational forces, (2) specialized capabilities for 1-g development and refinement of microgravity experiments, and (3) functional duplicates of flight hardware. Equipment diagrams are included.

  5. Ground based materials science experiments

    Science.gov (United States)

    Meyer, M. B.; Johnston, J. C.; Glasgow, T. K.

    1988-01-01

    The facilities at the Microgravity Materials Science Laboratory (MMSL) at the Lewis Research Center, created to offer immediate and low-cost access to ground-based testing facilities for industrial, academic, and government researchers, are described. The equipment in the MMSL falls into three categories: (1) devices which emulate some aspect of low gravitational forces, (2) specialized capabilities for 1-g development and refinement of microgravity experiments, and (3) functional duplicates of flight hardware. Equipment diagrams are included.

  6. Creating flat-top X-ray beams by applying surface profiles of alternating curvature to deformable piezo bimorph mirrors.

    Science.gov (United States)

    Sutter, John P; Alcock, Simon G; Kashyap, Yogesh; Nistea, Ioana; Wang, Hongchang; Sawhney, Kawal

    2016-11-01

    Beam shaping is becoming increasingly important for synchrotron X-ray applications. Although routine for visible light lasers, this is challenging for X-rays due to the limited source coherence and extreme optical tolerances required for the shaping mirrors. In deliberate defocusing, even surface errors piezo bimorph mirrors permit a continuous range of X-ray beam sizes and shapes. A new theory is developed for applying non-periodic modifications of alternating curvature to optical surfaces. The position and length of the segments may be freely chosen. For the first time, surface modifications of alternating curvature are applied to bimorph mirrors to generate non-Gaussian X-ray beam profiles of specified width. The new theory's freedom is exploited to choose the segments to match the polishing errors of medium wavelength (>10 mm) and the piezos' influence on the mirror's figure. Five- and seven-segment modifications of alternating curvature are calculated and verified by visible light and X-ray metrology. The latter yields beam profiles with less striation than those made by defocusing. Remaining beam striations are explained by applying geometrical optics to the deviations from the ideal surface modifications of alternating curvature.

  7. The STACEE Ground-Based Gamma-ray Observatory

    Science.gov (United States)

    Ragan, Ken

    2002-04-01

    The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a ground-based instrument designed to study astrophysical sources of gamma rays in the energy range from 50 to 500 GeV using an array of heliostat mirrors at the National Solar Thermal Test Facility in New Mexico. The mirrors collect Cherenkov light generated by gamma-ray air showers and concentrate it onto cameras composed of photomultiplier tubes. The STACEE instrument is now complete, and uses a total of 64 heliostats. Prototype instruments, using smaller numbers of heliostats, have previously detected gamma emission from both the Crab Nebula and the Active Galactic Nucleus Mrk421. The complete instrument has a lower threshold -- approximately 50 GeV -- than those prototypes due to superior triggering and electronics, including flash ADCs for every channel.We will discuss the performance of the complete instrument in its first full season of operation, and present preliminary results of selected observations.

  8. Progress in the ULTRA 1-m ground-based telescope

    Science.gov (United States)

    Romeo, Robert C.; Martin, Robert N.; Twarog, Bruce; Anthony-Twarog, Barbara; Taghavi, Ray; Hale, Rick; Etzel, Paul; Fesen, Rob; Shawl, Steve

    2006-06-01

    We present the technical status of the Ultra Lightweight Telescope for Research in Astronomy (ULTRA) program. The program is a 3-year Major Research Instrumentation (MRI) program funded by NSF. The MRI is a collaborative effort involving Composite Mirror Applications, Inc. (CMA), University of Kansas, San Diego State University and Dartmouth College. Objectives are to demonstrate the feasibility of carbon fiber reinforced plastic (CFRP) composite mirror technology for ground-based optical telescopes. CMA is spearheading the development of surface replication techniques to produce the optics, fabricating the 1m glass mandrel, and constructing the optical tube assembly (OTA). Presented will be an overview and status of the 1-m mandrel fabrication, optics development, telescope design and CFRP telescope fabrication by CMA for the ULTRA Telescope.

  9. Close-loop performance of a high precision deflectometry controlled deformable mirror (DCDM) unit for wavefront correction in adaptive optics system

    Science.gov (United States)

    Huang, Lei; Zhou, Chenlu; Zhao, Wenchuan; Choi, Heejoo; Graves, Logan; Kim, Daewook

    2017-06-01

    We present a high precision deflectometry system (DS) controlled deformable mirror (DM) solution for optical system. Different from wavefront and non-wavefront system, the DS and the DM are set to be an individual integrated DCDM unit and can be installed in one base plate. In the DCDM unit, the DS can directly provide the influence functions and surface shape of the DM to the industrial computer in any adaptive optics system. As an integrated adaptive unit, the DCDM unit could be put into various optical systems to realize aberration compensation. In this paper, the configuration and principle of the DCDM unit is introduced first. Theoretical simulation on the close-loop performance of the DCDM unit is carried out. Finally, a verification experiment is proposed to verify the compensation capability of the DCDM unit.

  10. The Actuator Design and the Experimental Tests of a New Technology Large Deformable Mirror for Visible Wavelengths Adaptive Optics

    CERN Document Server

    Del Vecchio, Ciro; Arcidiacono, Carmelo; Carbonaro, Luca; Marignetti, Fabrizio; De Santis, Enzo; Biliotti, Valdemaro; Riccardi, Armando

    2012-01-01

    Recently, Adaptive Secondary Mirrors showed excellent on-sky results in the Near Infrared wavelengths. They currently provide 30mm inter-actuator spacing and about 1 kHz bandwidth. Pushing these devices to be operated at visible wavelengths is a challenging task. Compared to the current systems, working in the infrared, the more demanding requirements are the higher spatial resolution and the greater correction bandwidth. In fact, the turbulence scale is shorter and the parameter variation is faster. Typically, the former is not larger than 25 mm (projected on the secondary mirror) and the latter is 2 kHz, therefore the actuator has to be more slender and faster than the current ones. With a soft magnetic composite core, a dual-stator and a single-mover, VRALA, the actuator discussed in this paper, attains unprecedented performances with a negligible thermal impact. Pre-shaping the current required to deliver a given stroke greatly simplifies the control system, whose output supplies the current generator. As...

  11. Ground-based observations of exoplanet atmospheres

    NARCIS (Netherlands)

    Mooij, Ernst Johan Walter de

    2011-01-01

    This thesis focuses on the properties of exoplanet atmospheres. The results for ground-based near-infrared secondary eclipse observations of three different exoplanets, TrES-3b, HAT-P-1b and WASP-33b, are presented which have been obtained with ground-based telescopes as part of the GROUSE project.

  12. Ground-based observations of exoplanet atmospheres

    NARCIS (Netherlands)

    Mooij, Ernst Johan Walter de

    2011-01-01

    This thesis focuses on the properties of exoplanet atmospheres. The results for ground-based near-infrared secondary eclipse observations of three different exoplanets, TrES-3b, HAT-P-1b and WASP-33b, are presented which have been obtained with ground-based telescopes as part of the GROUSE project.

  13. Development of binary image masks for TPF-C and ground-based AO coronagraphs

    Science.gov (United States)

    Ge, Jian; Crepp, Justin; Vanden Heuvel, Andrew; Miller, Shane; McDavitt, Dan; Kravchenko, Ivan; Kuchner, Marc

    2006-06-01

    We report progress on the development of precision binary notch-filter focal plane coronagraphic masks for directly imaging Earth-like planets at visible wavelengths with the Terrestrial Planet Finder Coronagraph (TPF-C), and substellar companions at near infrared wavelengths from the ground with coronagraphs coupled to high-order adaptive optics (AO) systems. Our recent theoretical studies show that 8th-order image masks (Kuchner, Crepp & Ge 2005, KCG05) are capable of achieving unlimited dynamic range in an ideal optical system, while simultaneously remaining relatively insensitive to low-spatial-frequency optical aberrations, such as tip/tilt errors, defocus, coma, astigmatism, etc. These features offer a suite of advantages for the TPF-C by relaxing many control and stability requirements, and can also provide resistance to common practical problems associated with ground-based observations; for example, telescope flexure and low-order errors left uncorrected by the AO system due to wavefront sensor-deformable mirror lag time can leak light at significant levels. Our recent lab experiments show that prototype image masks can generate contrast levels on the order of 2x10 -6 at 3 λ/D and 6x10 -7 at 10 λ/D without deformable mirror correction using monochromatic light (Crepp et al. 2006), and that this contrast is limited primarily by light scattered by imperfections in the optics and extra diffraction created by mask construction errors. These experiments also indicate that the tilt and defocus sensitivities of high-order masks follow the theoretical predictions of Shaklan and Green 2005. In this paper, we discuss these topics as well as review our progress on developing techniques for fabricating a new series of image masks that are "free-standing", as such construction designs may alleviate some of the (mostly chromatic) problems associated with masks that rely on glass substrates for mechanical support. Finally, results obtained from our AO coronagraph

  14. 激光辐照下镀铬介质高吸收镜的热变形%Thermal deformation of high absorption chrome plated mirror irradiated by laser

    Institute of Scientific and Technical Information of China (English)

    聂山钧; 郭劲; 邵俊峰; 王挺峰; 汤伟

    2015-01-01

    In order to analyze the effect of thermal deformation of the mirror irradiated by laser beam on the beam quality , thermal-static structural coupled model of high absorption chrome plated mirror irradiated by la-ser beam with the incidence angle of 45°is built.Thermal deformation under different irradiation laser and the influence of mirror thickness on the deformation are analyzed .Then thermal deformation is detected with Hart-mann wavefront sensor on free boundary condition .The results show that thermal deformation increases approx-imately linearly with the increase of the power absorbed at the range of 0.085-0.185 W.When the diameter of the facula increases , the deformation decreases .When mirror's thickness keeps in the range of 1~5 mm, the deformation merely keeps constant .In the initial stage of laser irradiation , the temperature and deformation increase rapidly .After 20 s, the increase of temperature on the mirror becomes slowly .The deformation in-creases to 0.27 μm in 1 s, and then increase slowly .The deformation will reach balance after 100 s.When the irradiation laser is removed , the mirror will return to the initial state after 120 s.The analysis result shows that the testing error is mainly caused by the error of the diameter of the facula and the incident angle of the la -ser .%为了分析激光辐照下反射镜热变形对光束质量的影响,本文建立了激光光束45°角入射时镀铬介质高吸收镜的热固耦合模型,对不同辐照光束下反射镜的热变形和镜体厚度对热变形的影响进行了分析,并用哈特曼波前传感器对自由边界条件下的镜面热变形进行了检测。结果表明:吸收功率在0.085~0.185 W时,镜面热变形随吸收功率的增加近似线性增加,随辐照光斑的增加而减小;反射镜厚度在1~5 mm范围,镜面热变形基本不变。在激光照射的初始阶段,反射镜表面温度和热变形迅速增加,在激光连续照射20 s后

  15. Fresnel zones for ground-based antennas

    DEFF Research Database (Denmark)

    Andersen, J. Bach

    1964-01-01

    The ordinary Fresnel zone concept is modified to include the influence of finite ground conductivity. This is important for ground-based antennas because the influence on the radiation pattern of irregularities near the antenna is determined by the amplitude and phase of the groundwave. A new...

  16. Calibration of Ground-based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement unce...

  17. Calibration of Ground -based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Yordanova, Ginka

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement unce...

  18. 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.

  19. A demonstration of wavefront sensing and mirror phasing from the image domain

    Science.gov (United States)

    Pope, Benjamin; Cvetojevic, Nick; Cheetham, Anthony; Martinache, Frantz; Norris, Barnaby; Tuthill, Peter

    2014-05-01

    In astronomy and microscopy, distortions in the wavefront affect the dynamic range of a high-contrast imaging system. These aberrations are either imposed by a turbulent medium such as the atmosphere, by static or thermal aberrations in the optical path, or by imperfectly phased subapertures in a segmented mirror. Active and adaptive optics (AO), consisting of a wavefront sensor and a deformable mirror, are employed to address this problem. Nevertheless, the non-common-path between the wavefront sensor and the science camera leads to persistent quasi-static speckles that are difficult to calibrate and which impose a floor on the image contrast. In this paper, we present the first experimental demonstration of a novel wavefront sensor requiring only a minor asymmetric obscuration of the pupil, using the science camera itself to detect high-order wavefront errors from the speckle pattern produced. We apply this to correct errors imposed on a deformable microelectromechanical segmented mirror in a closed loop, restoring a high-quality point spread function and residual wavefront errors of the order of ˜10 nm using 1600 nm light, from a starting point of ˜300 nm in piston and ˜0.3 mrad in tip-tilt. We recommend this as a method for measuring the non-common-path error in AO-equipped ground based telescopes, as well as an approach to phasing difficult segmented mirrors such as on the James Webb Space Telescope primary and as a future direction for extreme AO.

  20. Design, fabrication and characterization of high-stroke high-aspect ratio micro electro mechanical systems deformable mirrors for adaptive optics

    Science.gov (United States)

    Fernandez Rocha, Bautista

    Adaptive optic (AO) systems for next generation of extremely large telescopes (30--50 meter diameter primary mirrors) require high-stroke (10 microns), high-order (100x100) deformable mirrors at lower-cost than current technology. The required specifications are achievable with Micro Electro Mechanical Systems (MEMS) devices fabricated with high-aspect ratio processing techniques. This dissertation will review simulation results compared with displacement measurements of actuators utilizing a white-light interferometer. It will also review different actuator designs, materials and post-processing procedures fabricated in three different high-aspect ratio processes, Microfabrica's Electrochemical Fabrication (EFAB(TM)), HT-Micro's Precision Fabrication Technology (HTPF(TM)), and Innovative Micro Technologies (IMT) fabrication process. These manufacturing processes allow high-precision multilayer fabrication and their sacrificial layer thicknesses can be specified by the designer, rather than by constraints of the fabrication process. Various types of high-stroke gold actuators for AO consisting of folded springs with rectangular and circular membranes as well as X-beam actuators supported diagonally by beams were designed, simulated, fabricated, and tested individually and as part of a continuous facesheet DM system. The design, modeling and simulation of these actuators are compared to experimental measurements of their pull-in voltages, which characterizes their stiffness and maximum stroke. Vertical parallel plate ganged actuators fabricated with the EFAB(TM) process have a calculated pull-in voltage of 95V for a 600mum size device. In contrast, the pull-in voltages for the comb-drive actuators ranged from 55V for the large actuator, to 203V for the smallest actuator. Simulations and interferometer scans of actuator designs fabricated with HT-Micro's Precision Fabrication (HTPF(TM)) two wafer bonded process with different spring supports have shown the ability of

  1. Space and Ground-Based Infrastructures

    Science.gov (United States)

    Weems, Jon; Zell, Martin

    This chapter deals first with the main characteristics of the space environment, outside and inside a spacecraft. Then the space and space-related (ground-based) infrastructures are described. The most important infrastructure is the International Space Station, which holds many European facilities (for instance the European Columbus Laboratory). Some of them, such as the Columbus External Payload Facility, are located outside the ISS to benefit from external space conditions. There is only one other example of orbital platforms, the Russian Foton/Bion Recoverable Orbital Capsule. In contrast, non-orbital weightless research platforms, although limited in experimental time, are more numerous: sounding rockets, parabolic flight aircraft, drop towers and high-altitude balloons. In addition to these facilities, there are a number of ground-based facilities and space simulators, for both life sciences (for instance: bed rest, clinostats) and physical sciences (for instance: magnetic compensation of gravity). Hypergravity can also be provided by human and non-human centrifuges.

  2. Development of Ground-Based Plant Sentinels

    Science.gov (United States)

    2007-11-02

    plants in response to different strains of Pseudomonas syringae. Planta . 217:767-775. De Moraes CM, Schultz JC, Mescher MC, Tumlinson JH. (2004...09-30-2004 Final Technical _ April 2001 - April 2003 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Developing Plants as Ground-based Sentinels 5b. GRANT...SUPPLEMENTARY NOTES 14. ABSTRACT 9 "Z Plants emit volatile mixes characteristic of exposure to both plant and animal (insect) pathogens (bacteria and fungi). The

  3. Illumination compensation in ground based hyperspectral imaging

    Science.gov (United States)

    Wendel, Alexander; Underwood, James

    2017-07-01

    Hyperspectral imaging has emerged as an important tool for analysing vegetation data in agricultural applications. Recently, low altitude and ground based hyperspectral imaging solutions have come to the fore, providing very high resolution data for mapping and studying large areas of crops in detail. However, these platforms introduce a unique set of challenges that need to be overcome to ensure consistent, accurate and timely acquisition of data. One particular problem is dealing with changes in environmental illumination while operating with natural light under cloud cover, which can have considerable effects on spectral shape. In the past this has been commonly achieved by imaging known reference targets at the time of data acquisition, direct measurement of irradiance, or atmospheric modelling. While capturing a reference panel continuously or very frequently allows accurate compensation for illumination changes, this is often not practical with ground based platforms, and impossible in aerial applications. This paper examines the use of an autonomous unmanned ground vehicle (UGV) to gather high resolution hyperspectral imaging data of crops under natural illumination. A process of illumination compensation is performed to extract the inherent reflectance properties of the crops, despite variable illumination. This work adapts a previously developed subspace model approach to reflectance and illumination recovery. Though tested on a ground vehicle in this paper, it is applicable to low altitude unmanned aerial hyperspectral imagery also. The method uses occasional observations of reference panel training data from within the same or other datasets, which enables a practical field protocol that minimises in-field manual labour. This paper tests the new approach, comparing it against traditional methods. Several illumination compensation protocols for high volume ground based data collection are presented based on the results. The findings in this paper are

  4. Ground based spectroscopy of hot Jupiters

    Science.gov (United States)

    Waldmann, Ingo

    2010-05-01

    It has been shown in recent years with great success that spectroscopy of exoplanetary atmospheres is feasible using space based observatories such as the HST and Spitzer. However, with the end of the Spitzer cold-phase, space based observations in the near to mid infra-red are limited, which will remain true until the the onset of the JWST. The importance of developing methods of ground based spectroscopic analysis of known hot Jupiters is therefore apparent. In the past, various groups have attempted exoplanetary spectroscopy using ground based facilities and various techniques. Here I will present results using a novel spectral retrieval method for near to mid infra-red emission and transmission spectra of exoplanetary atmospheres taken from the ground and discuss the feasibility of future ground-based spectroscopy in a broader context. My recently commenced PhD project is under the supervision of Giovanna Tinetti (University College London) and in collaboration with J. P. Beaulieu (Institut d'Astrophysique de Paris), Mark Swain and Pieter Deroo (Jet Propulsion Laboratory, Caltech).

  5. 强光辐照下白宝石高反镜尺寸对热变形的影响%Effect of dimensions on thermal deformation of high reflectance sapphire mirrors under high power laser irradiation

    Institute of Scientific and Technical Information of China (English)

    梅艳莹; 杨涛

    2014-01-01

    为了进一步减小白宝石( Al2 O3)高反镜在强光辐照下的热变形,提高光束质量,研究了白宝石高反镜厚度、直径尺寸对热变形的影响。采用以极坐标表示的热传导方程和热变形公式来描述白宝石高反镜的温度场分布和位移场分布;在有限元分析软件中建立数值计算模型,并计算了不同厚度、直径尺寸下的温度场和位移场,得到了热变形随厚度尺寸和直径尺寸变化的规律。结果表明,影响白宝石高反镜反射面峰谷值变化的主要因素是温度,而尺寸变化对温度和刚度均有影响;选择合适的高反镜直径和厚度尺寸,可以有效降低镜面温升,同时得到合适的轴向结构刚度,从而减小反射镜镜面热变形。该研究结果对强光辐照下白宝石高反镜尺寸设计和选择具有一定的参考价值。%In order to reduce thermal deformation of high reflectance sapphire mirrors under high power laser irradiation and improve the beam quality , effect of the diameter and thickness on thermal deformation of the high reflectance mirror was studied .The heat conduction equation expressed in polar coordinate and the thermal deformation formula were used to describe the distribution of the temperature field and the displacement field of the sapphire mirror .Then, the numerical calculation model was built with the finite element analysis software and the temperature field and displacement field in different thickness and diameter was calculated .The thermal deformation with respect to the thickness and diameter was obtained .The results indicate that the main factors affecting the PV value of the sapphire mirror surface is the temperature variation and the change of the size has effect on both temperature and stiffness .Appropriate size and thickness effectively reduce the rise of mirror ’ s temperature and keep suitable axial structural stiffness , and thus the thermal deformation of the

  6. 流道截面参量对微通道水冷镜热变形的影响%Influence of Channel Parameters on Thermal-Deformation of Microchannel Mirror

    Institute of Scientific and Technical Information of China (English)

    胡攀攀; 朱海红; 左都罗

    2011-01-01

    采用将有限体积法求解三维层流传热方程获得的温度场耦合到ANSYS进行热变形分析的方法,研究了流道截面形状和尺寸对微通道水冷镜内传热现象和镜面热畸变的影响.计算了矩形、梯形、圆形3种截面形状以及3种不同水力直径(百微米量级)下微通道水冷镜的平均换热系数、温升和镜面热变形.结果表明,同一条流道,各壁面温度并不随激光辐照面和镜面呈对称分布,最高温度偏向下游;侧壁的换热系数最大,且沿水流方向逐步减小;流道距进水口距离越大,其换热系数越小.在3种截面形状微通道中,减小截面尺寸可获得较大换热系数,且梯形截面微通道水冷镜能获得最小的镜面热变形量,在热流密度为14730 W/m2,水力直径为239 μm,入口速度为2.54 m/s的条件下,其镜面热变形仅为0.016 μm.%The effect of cross-section shape and geometrical parameters of the channel on heat transfer and thermal deformation of the microchannel water-cooled mirror is studied by analyzing the temperature field obtained by using finite volume method to solve the three-dimensional steady laminar flow and heat transfer equations, and the deformation obtained by coupling the temperature field to ANSYS software. Three different cross-section shapes of microchannel, i.e., rectangle, trapezoid and circle, are investigated in this paper. Average heat transfer coefficient, temperature increasing and thermal deformation of mirror of each shape examined with three geometrical dimensions, are simulated. It is found that for the same channel, temperature distribution is not symmetrical, the highest temperature moves to the downstream, the heat transfer coefficient of each interface is also different, the heat transfer coefficient of side wall is the biggest, heat transfer coefficient of other walls decreases along the water flow direction. For the mirror using the same shape microchannel and hydraulic diameter, the

  7. 反射镜热畸变对激光光束质量影响的研究%Influence of mirror thermal deformation on beam quality of laser

    Institute of Scientific and Technical Information of China (English)

    李艳娜; 谢翔云; 王刚; 唐力铁

    2016-01-01

    基于热传导理论,建立了高斯光束辐照硅反射镜的物理模型,利用多物理场数值分析软件 COMSOL Multiphysics 求解热传导方程,仿真计算得到镜面表面温度分布曲线以及镜面变形曲线,进一步结合光学仿真软件模拟计算,研究得到 Si 反射镜镜面的热畸变对输出光束质量的影响。结果表明:随着激光辐照时间的增大,反射镜热变形越显著,输出光束质量β因子越大,但β值的变化首先较快而后趋于平缓。随着辐照激光功率的增加,反射镜热变形越大,输出光束质量β因子不断增大。%The physical models of Si mirror under Gauss laser irradiation was built based on heat transfer theory.The temperature field and thermal deformation distributions on the mirror surface were calculated and analyzed by using Comsol Multiphysics software.And then the effect of thermal distortion of Si mirror on output beam quality of high -power laser has also been analyzed combining with simulation software.The results show that Si mirror thermal de-formation increases with the increase of the irradiation time,and beam quality factor βincreases accordingly,but βin-creased significantly and then approaches flat with the increase of the irradiation time.Beam quality and mirror ther-mal deformation also increase with the increase of the laser power.

  8. Calibration of Ground-based Lidar instrument

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Gómez Arranz, Paula

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement...... uncertainties provided by measurement standard and corresponding lidar wind speed indications with associated measurement uncertainties. The lidar calibration concerns the 10 minute mean wind speed measurements. The comparison of the lidar measurements of the wind direction with that from wind vanes...

  9. Calibration of Ground-based Lidar instrument

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Gómez Arranz, Paula

    This report presents the result of a test of a ground-based lidar of other type. The test was performed at DTU’s test site for large wind turbines at Høvsøre, Denmark. The result as an establishment of a relation between the reference wind speed measurements with measurement uncertainties provided...... by measurement standard and corresponding lidar wind speed indications with associated measurement uncertainties. The comparison of the lidar measurements of the wind direction with that from the wind vanes is also given....

  10. Calibration of Ground -based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Yordanova, Ginka

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement...... uncertainties provided by measurement standard and corresponding lidar wind speed indications with associated measurement uncertainties. The lidar calibration concerns the 10 minute mean wind speed measurements. The comparison of the lidar measurements of the wind direction with that from wind vanes...

  11. Calibration of Ground-based Lidar instrument

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Gómez Arranz, Paula

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement...... uncertainties provided by measurement standard and corresponding lidar wind speed indications with associated measurement uncertainties. The lidar calibration concerns the 10 minute mean wind speed measurements. The comparison of the lidar measurements of the wind direction with that from wind vanes...

  12. Calibration of Ground -based Lidar instrument

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Georgieva Yankova, Ginka

    This report presents the result of the lidar calibration performed for the given Ground-based Lidar at DTU’s test site for large wind turbines at Høvsøre, Denmark. Calibration is here understood as the establishment of a relation between the reference wind speed measurements with measurement...... uncertainties provided by measurement standard and corresponding lidar wind speed indications with associated measurement uncertainties. The lidar calibration concerns the 10 minute mean wind speed measurements. The comparison of the lidar measurements of the wind direction with that from wind vanes...

  13. Einstein's Mirror

    Science.gov (United States)

    Gjurchinovski, Aleksandar; Skeparovski, Aleksandar

    2008-01-01

    Reflection of light from a plane mirror in uniform rectilinear motion is a century-old problem, intimately related to the foundations of special relativity. The problem was first investigated by Einstein in his famous 1905 paper by using the Lorentz transformations to switch from the mirror's rest frame to the frame where the mirror moves at a…

  14. Study on the control of micro- deformation of resonator mirrors and windows in high power laser%控制高功率激光器腔镜与窗口微变形技术的探讨

    Institute of Scientific and Technical Information of China (English)

    马梦林; 郭劲; 张来明; 杨飞

    2007-01-01

    A few of technologies are demonstrated, such as the water- cooling, the thermoelectric cooling,the phase - change cooling and so on. All of these are induced to minimize the thermal deformation and damage of resonator mirrors and windows in high power laser. According to the working principle, these technologies are used in different lasers. The application of multi - layer complex liquid - cooling technology is more extensive, which can reduce effectively heating effect of the high power laser. And then the mirror surface deformation of the high power laser system is controlled.%阐述了用来控制和改善高功率激光器腔镜及其窗口热变形产生的破坏的几种技术,如水冷技术、半导体致冷技术和相变致冷等技术.由于各种技术应用原理不同,其适用的范围也有很大的差别.其中一种新技术多层水冷技术适应性比较广,并且能有效地减少高功率激光器热效应对其光学元件的影响,从而使镜面变形得到很好的控制.

  15. Chiral mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Plum, Eric, E-mail: erp@orc.soton.ac.uk [Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Zheludev, Nikolay I., E-mail: niz@orc.soton.ac.uk [Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); The Photonics Institute and Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637378 (Singapore)

    2015-06-01

    Mirrors are used in telescopes, microscopes, photo cameras, lasers, satellite dishes, and everywhere else, where redirection of electromagnetic radiation is required making them arguably the most important optical component. While conventional isotropic mirrors will reflect linear polarizations without change, the handedness of circularly polarized waves is reversed upon reflection. Here, we demonstrate a type of mirror reflecting one circular polarization without changing its handedness, while absorbing the other. The polarization-preserving mirror consists of a planar metasurface with a subwavelength pattern that cannot be superimposed with its mirror image without being lifted out of its plane, and a conventional mirror spaced by a fraction of the wavelength from the metasurface. Such mirrors enable circularly polarized lasers and Fabry-Pérot cavities with enhanced tunability, gyroscopic applications, polarization-sensitive detectors of electromagnetic waves, and can be used to enhance spectroscopies of chiral media.

  16. Deformation Analysis of Laser Cavity Mirror and Method of Heat Pipe Cooling%激光器腔镜变形分析及热管冷却方法研究

    Institute of Scientific and Technical Information of China (English)

    刘丽; 安朝卫; 宋洁冰; 毕祥丽

    2011-01-01

    激光器运行中,腔镜的变形造成激光输出功率下降和光束质量变坏,大大制约了高功率激光器性能的提高。通过对激光器腔镜吸热产生的热变形及冷却流体对镜片压力变形分析,提出了热管冷却腔镜的方法,介绍了热管冷却原理和热管在导热方面的优点,设计了热管冷却腔镜方案,为有效控制强激光系统中镜片表面变形提供了有效途径。%The cavity deformation can lead to the decline in the laser output power and the beam quality de terioration when the laser operates,so the performance enhancement of the high power laser is restricted greatly.The heat deformation based on the heat absorption of the laser cavity and the lens pressure deformation based on cooling fluid are analyzed,the method of the heat pipe cooling cavity mirror is proposed.The principle of the heat pipe cooling and the advantage of heat pipe in heat conductivity are introduced,the solution of heat pipe cooling cavity mirror is designed,which provides the effective way to effectively control the lens surface defor mation of the high power laser system.

  17. 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.

  18. Magic Mirrors

    Science.gov (United States)

    Mills, Allan

    2011-01-01

    "Magic mirrors" were so named because, when they were positioned to throw a reflected patch of sunlight on a nearby wall, this area contained an outline of a design cast on the back of the (bronze) mirror. Investigations begun in the 19th century showed that this was a response to heavy localized pressures exerted on the face of the thin mirror…

  19. Shell Separation for Mirror Replication

    Science.gov (United States)

    1999-01-01

    NASA's Space Optics Manufacturing Center has been working to expand our view of the universe via sophisticated new telescopes. The Optics Center's goal is to develop low-cost, advanced space optics technologies for the NASA program in the 21st century - including the long-term goal of imaging Earth-like planets in distant solar systems. To reduce the cost of mirror fabrication, Marshall Space Flight Center (MSFC) has developed replication techniques, the machinery, and materials to replicate electro-formed nickel mirrors. Optics replication uses reusable forms, called mandrels, to make telescope mirrors ready for final finishing. MSFC optical physicist Bill Jones monitors a device used to chill a mandrel, causing it to shrink and separate from the telescope mirror without deforming the mirror's precisely curved surface.

  20. Mirror symmetry

    CERN Document Server

    Voisin, Claire

    1999-01-01

    This is the English translation of Professor Voisin's book reflecting the discovery of the mirror symmetry phenomenon. The first chapter is devoted to the geometry of Calabi-Yau manifolds, and the second describes, as motivation, the ideas from quantum field theory that led to the discovery of mirror symmetry. The other chapters deal with more specialized aspects of the subject: the work of Candelas, de la Ossa, Greene, and Parkes, based on the fact that under the mirror symmetry hypothesis, the variation of Hodge structure of a Calabi-Yau threefold determines the Gromov-Witten invariants of its mirror; Batyrev's construction, which exhibits the mirror symmetry phenomenon between hypersurfaces of toric Fano varieties, after a combinatorial classification of the latter; the mathematical construction of the Gromov-Witten potential, and the proof of its crucial property (that it satisfies the WDVV equation), which makes it possible to construct a flat connection underlying a variation of Hodge structure in the ...

  1. Mirror neurons

    National Research Council Canada - National Science Library

    Rubia Vila, Francisco José

    2011-01-01

    Mirror neurons were recently discovered in frontal brain areas of the monkey. They are activated when the animal makes a specific movement, but also when the animal observes the same movement in another animal...

  2. Ground-based observations of Kepler asteroseismic targets

    DEFF Research Database (Denmark)

    Uyttterhoeven , K.; Karoff, Christoffer

    2010-01-01

    We present the ground-based activities within the different working groups of the Kepler Asteroseismic Science Consortium (KASC). The activities aim at the systematic characterization of the 5000+ KASC targets, and at the collection of ground-based follow-up time-series data of selected promising...

  3. Movable Ground Based Recovery System for Reuseable Space Flight Hardware

    Science.gov (United States)

    Sarver, George L. (Inventor)

    2013-01-01

    A reusable space flight launch system is configured to eliminate complex descent and landing systems from the space flight hardware and move them to maneuverable ground based systems. Precision landing of the reusable space flight hardware is enabled using a simple, light weight aerodynamic device on board the flight hardware such as a parachute, and one or more translating ground based vehicles such as a hovercraft that include active speed, orientation and directional control. The ground based vehicle maneuvers itself into position beneath the descending flight hardware, matching its speed and direction and captures the flight hardware. The ground based vehicle will contain propulsion, command and GN&C functionality as well as space flight hardware landing cushioning and retaining hardware. The ground based vehicle propulsion system enables longitudinal and transverse maneuverability independent of its physical heading.

  4. DATA PROCESSING AND ANALYSIS TOOLS BASED ON GROUND-BASED SYNTHETIC APERTURE RADAR IMAGERY

    Directory of Open Access Journals (Sweden)

    M. Crosetto

    2017-09-01

    Full Text Available The Ground-Based SAR (GBSAR is a terrestrial remote sensing technique used to measure and monitor deformation. In this paper we describe two complementary approaches to derive deformation measurements using GBSAR data. The first approach is based on radar interferometry, while the second one exploits the GBSAR amplitude. In this paper we consider the so-called discontinuous GBSAR acquisition mode. The interferometric process is not always straightforward: it requires appropriate data processing and analysis tools. One of the main critical steps is phase unwrapping, which can critically affect the deformation measurements. In this paper we describe the procedure used at the CTTC to process and analyse discontinuous GBSAR data. In the second part of the paper we describe the approach based on GBSAR amplitude images and an image-matching method.

  5. Mirror, mirror on the wall

    CERN Multimedia

    2005-01-01

    RICH 2, one of the two Ring Imaging Cherenkov detectors of the LHCb experiment, is being prepared to join the other detector elements ready for the first proton-proton collisions at LHC. The mirrors of the RICH2 detector are meticulously assembled in a clean room.In a large dark room, men in white move around an immense structure some 7 metres high, 10 metres wide and nearly 2.5 metres deep. Apparently effortlessly, they are installing the two large high-precision spherical mirrors. These mirrors will focus Cherenkov light, created by the charged particles that will traverse this detector, onto the photon detectors. Each spherical mirror wall is made up of facets like a fly's eye. Twenty-eight individual thin glass mirrors will all point to the same point in space to within a few micro-radians. The development of these mirrors has been technically demanding : Ideally they should be massless, sturdy, precise and have high reflectivity. In practice, though not massless, they are made from a mere 6 mm thin gl...

  6. Numerical study on mirror of high power laser with heatpipe cooling

    Science.gov (United States)

    Chen, Jiayuan, II; Zhu, Haihong; Cheng, Zuhai

    2008-12-01

    Mirror surface of high power laser would be deformed by the pressure of the coolant in a liquid cooling mirror system. In order to eliminate the impact of pressure and vibration of cooling water to the stability of the output beam, a cooling mirror with heatpipe is designed. With the same structure and conditions, solid mirror, water cooling mirror and heat pipe cooling mirror are simulated by ANSYS program. The time-varying thermal deformations of the group mirrors after 60s under the net heat absorption of 12W/cm2 are obtained. The maximal peak and valley difference value of mirror surface deformation of solid mirror along Z-axis, water cooling mirror and heat pipe cooling mirror after 60s is 1.33μm, 0.845 μm and 0.1094 μm respectively.

  7. [Mirror neurons].

    Science.gov (United States)

    Rubia Vila, Francisco José

    2011-01-01

    Mirror neurons were recently discovered in frontal brain areas of the monkey. They are activated when the animal makes a specific movement, but also when the animal observes the same movement in another animal. Some of them also respond to the emotional expression of other animals of the same species. These mirror neurons have also been found in humans. They respond to or "reflect" actions of other individuals in the brain and are thought to represent the basis for imitation and empathy and hence the neurobiological substrate for "theory of mind", the potential origin of language and the so-called moral instinct.

  8. Homological Perturbation Theory and Mirror Symmetry

    Institute of Scientific and Technical Information of China (English)

    Jian ZHOU

    2003-01-01

    We explain how deformation theories of geometric objects such as complex structures,Poisson structures and holomorphic bundle structures lead to differential Gerstenhaber or Poisson al-gebras. We use homological perturbation theory to construct A∞ algebra structures on the cohomology,and their canonically defined deformations. Such constructions are used to formulate a version of A∞algebraic mirror symmetry.

  9. What do mirror neurons mirror?

    NARCIS (Netherlands)

    Uithol, S.; Rooij, I.J.E.I. van; Bekkering, H.; Haselager, W.F.G.

    2011-01-01

    Single cell recordings in monkeys provide strong evidence for an important role of the motor system in action understanding. This evidence is backed up by data from studies of the (human) mirror neuron system using neuroimaging or TMS techniques, and behavioral experiments. Although the data acquire

  10. What do mirror neurons mirror?

    NARCIS (Netherlands)

    Uithol, S.; Rooij, I.J.E.I. van; Bekkering, H.; Haselager, W.F.G.

    2011-01-01

    Single cell recordings in monkeys provide strong evidence for an important role of the motor system in action understanding. This evidence is backed up by data from studies of the (human) mirror neuron system using neuroimaging or TMS techniques, and behavioral experiments. Although the data

  11. Toward a large lightweight mirror for AO: development of a 1m Ni coated CFRP mirror

    Science.gov (United States)

    Thompson, S. J.; Doel, A. P.; Brooks, D.; Strangwood, M.

    2008-07-01

    We present our recent developments towards the construction of a large, thin, single-piece mirror for adaptive optics (AO). Our current research program aims to have completed fabrication and testing of a 1m diameter, nickel coated carbon-fibre reinforced cyanate ester resin mirror by the last quarter of 2009. This composite mirror material is being developed to provide a lightweight and robust alternative to thin glass shell mirrors, with the challenge of future large deformable mirrors such as the 2.5m M4 on the E-ELT in mind. A detailed analysis of the material properties of test mirror samples is being performed at the University of Birmingham (UK), the first results of which are discussed and presented here. We discuss the project progress achieved so far, including fabrication of the 1m flat moulds for the replication process, manufacturing and testing methods for 20 cm diameter sample mirrors and system simulations.

  12. Mirror monochromator

    Energy Technology Data Exchange (ETDEWEB)

    Mankos, Marian [Electron Optica, Inc., Palo Alto, CA (United States); Shadman, Khashayar [Electron Optica, Inc., Palo Alto, CA (United States)

    2014-12-02

    In this SBIR project, Electron Optica, Inc. (EOI) is developing a mirror electron monochromator (MirrorChrom) attachment to new and retrofitted electron microscopes (EMs) for improving the energy resolution of the EM from the characteristic range of 0.2-0.5 eV to the range of 10-50 meV. This improvement will enhance the characterization of materials by imaging and spectroscopy. In particular, the monochromator will refine the energy spectra characterizing materials, as obtained from transmission EMs [TEMs] fitted with electron spectrometers, and it will increase the spatial resolution of the images of materials taken with scanning EMs (SEMs) operated at low voltages. EOI’s MirrorChrom technology utilizes a magnetic prism to simultaneously deflect the electron beam off the axis of the microscope column by 90° and disperse the electrons in proportional to their energies into a module with an electron mirror and a knife-edge. The knife-edge cuts off the tails of the energy distribution to reduce the energy spread of the electrons that are reflected, and subsequently deflected, back into the microscope column. The knife-edge is less prone to contamination, and thereby charging, than the conventional slits used in existing monochromators, which improves the reliability and stability of the module. The overall design of the MirrorChrom exploits the symmetry inherent in reversing the electron trajectory in order to maintain the beam brightness – a parameter that impacts how well the electron beam can be focused downstream onto a sample. During phase I, EOI drafted a set of candidate monochromator architectures and evaluated the trade-offs between energy resolution and beam current to achieve the optimum design for three particular applications with market potential: increasing the spatial resolution of low voltage SEMs, increasing the energy resolution of low voltage TEMs (beam energy of 5-20 keV), and increasing the energy resolution of conventional TEMs (beam

  13. Mirror systems

    Energy Technology Data Exchange (ETDEWEB)

    Howells, M.R.

    1985-12-01

    The physics of VUV and x-ray reflection is reviewed. The main functions of mirrors in synchrotron beamlines are stated briefly and include deflection, filtration, power absorption, formation of a real image of the source, focusing, and collimation. Methods of fabrication of optical surfaces are described. Types of imperfections are discussed, including, aberrations, surface figure inaccuracy, roughness, and degradation due to use. Calculation of the photon beam thermal load, including computer modelling, is considered. 50 refs., 7 figs. (LEW)

  14. Design and finite element analysis of lightmass silicon carbide primary mirror

    Institute of Scientific and Technical Information of China (English)

    HAN Yuan-yuan; ZHANG Yu-min; HAN Jie-cai; ZHANG Jian-han; YAO Wang; ZHOU Yu-feng

    2006-01-01

    Primary mirror is one of the key components in the space remote sensing system. To minimize the mass of the mirror without compromising its stiffness and decrease the deformation of the mirror surface at the different temperatures are the mainly two objects in the development of the primary mirror. Silicon carbide (SiC),the most promising optical material,was used as the material of the primary mirror with triangle lightmass structure in a Cassegrain system. By using finite element method,the properties of the SiC mirror were compared with that of the traditional Be mirror and fused silica mirror. The results of static,dynamic and thermo-mechanical analysis indicate that the deformation of the mirror surface caused by temperature field is much bigger than that caused by gravity field. The SiC mirror has the best overall properties,and the SiC material is much suitable for the primary mirror.

  15. Improved ground-based FTS measurement for column abundance CO2 retrievals(Conference Presentation)

    Science.gov (United States)

    Goo, Tae-Young

    2016-10-01

    The National Institute of Meteorological Sciences has operated a ground-based Fourier Transform Spectrometer (FTS) at Anmyeondo, Korea since December 2012. Anmyeondo FTS site is a designated operational station of Total Carbon Column Observing Network (TCCON) and belongs to regional Global Atmosphere Watch observatory. A Bruker IFS-125HR model, which has a significantly high spectral resolution by 0.02 cm-1, is employed and instrument specification is almost same as the TCCON configuration. such as a spectrum range of 3,800 16,000 cm-1, a resolution of 1 cm-1, InGaAs and Si-Diode detectors and CaF2 beam splitter. It is found that measured spectra have a good agreement with simulated spectra. In order to improve the spectral accuracy and stability, The Operational Automatic System for Intensity of Sunray (OASIS) has been developed. The OASIS can provide consistent photon energy optimized to detector range by controlling the diameter of solar beam reflected from the mirror of suntracker. As a result, monthly modulation efficiency (ME), which indicates the spectral accuracy of FTS measurement, has been recorded the vicinity of 99.9% since Feb 2015. The ME of 98% is regarded as the error of 0.1% in the ground-based in-situ CO2 measurement. Total column abundances of CO2 and CH4 during 2015 are estimated by using GGG v14 and compared with ground-based in-situ CO2 and CH4 measurements at the height of 86 m above sea level. The seasonality of CO2 is well captured by both FTS and in-situ measurements while there is considerable difference on the amplitude of CO2 seasonal variation due to the insensitivity of column CO2 to the surface carbon cycle dynamics in nature as well as anthropogenic sources. Total column CO2 and CH4 approximately vary from 395 ppm to 405 ppm and from 1.82 ppm to 1.88 ppm, respectively. It should be noted that few measurements obtained in July to August because of a lot of cloud and fog. It is found that enhancement of CH4 from the FTS at Anmyeondo

  16. GLAST and Ground-Based Gamma-Ray Astronomy

    Science.gov (United States)

    McEnery, Julie

    2008-01-01

    The launch of the Gamma-ray Large Area Space Telescope together with the advent of a new generation of ground-based gamma-ray detectors such as VERITAS, HESS, MAGIC and CANGAROO, will usher in a new era of high-energy gamma-ray astrophysics. GLAST and the ground based gamma-ray observatories will provide highly complementary capabilities for spectral, temporal and spatial studies of high energy gamma-ray sources. Joint observations will cover a huge energy range, from 20 MeV to over 20 TeV. The LAT will survey the entire sky every three hours, allowing it both to perform uniform, long-term monitoring of variable sources and to detect flaring sources promptly. Both functions complement the high-sensitivity pointed observations provided by ground-based detectors. Finally, the large field of view of GLAST will allow a study of gamma-ray emission on large angular scales and identify interesting regions of the sky for deeper studies at higher energies. In this poster, we will discuss the science returns that might result from joint GLAST/ground-based gamma-ray observations and illustrate them with detailed source simulations.

  17. GLAST and Ground-Based Gamma-Ray Astronomy

    Science.gov (United States)

    McEnery, Julie

    2008-01-01

    The launch of the Gamma-ray Large Area Space Telescope together with the advent of a new generation of ground-based gamma-ray detectors such as VERITAS, HESS, MAGIC and CANGAROO, will usher in a new era of high-energy gamma-ray astrophysics. GLAST and the ground based gamma-ray observatories will provide highly complementary capabilities for spectral, temporal and spatial studies of high energy gamma-ray sources. Joint observations will cover a huge energy range, from 20 MeV to over 20 TeV. The LAT will survey the entire sky every three hours, allowing it both to perform uniform, long-term monitoring of variable sources and to detect flaring sources promptly. Both functions complement the high-sensitivity pointed observations provided by ground-based detectors. Finally, the large field of view of GLAST will allow a study of gamma-ray emission on large angular scales and identify interesting regions of the sky for deeper studies at higher energies. In this poster, we will discuss the science returns that might result from joint GLAST/ground-based gamma-ray observations and illustrate them with detailed source simulations.

  18. Lightweight Metal Mirrors

    Science.gov (United States)

    Gossett, E.; Winslow, P.

    1984-01-01

    Two "eggcrate" halves brazed together. Lightweight flat mirrors fabricated by machining pockets in two plates of beryllium and brazing machined halves together. Mirror less than half weight of same mirror made by previous design.

  19. Lightweight design and finite element analysis of primary mirror for the space telescope

    Science.gov (United States)

    Zhang, Dandan; Li, Weiyan; Lv, Qunbo; Liu, Yangyang; Chen, Xinwen

    2015-09-01

    In order to satisfy the strict requirements of the lightweight ratios and high dimensional stability for space mirror, the design method of lightweight structure and the flexible supporting structure of the primary mirror is proposed. Subsequently, the surface deformations of two different lightweight structures for primary mirror are discussed for analyzing the influence of the mirror weight on its surface. Finally, the finite element models for primary mirror assembly are built for calculating the surface deformation caused by different gravity orientations and various thermal environments. It is proved that the weight, stiffness and surface accuracy of the structure design for primary mirror can meet the engineering requirement.

  20. Large thin adaptive x-ray mirrors

    Science.gov (United States)

    Doel, Peter; Atkins, Carolyn; Thompson, Samantha; Brooks, David; Yao, Jun; Feldman, Charlotte; Willingale, Richard; Button, Tim; Zhang, Dou; James, Ady

    2007-09-01

    This paper describes the progress made in a proof of concept study and recent results of a research program into large active x-ray mirrors that is part of the UK Smart X-ray Optics project. The ultimate aim is to apply the techniques of active/adaptive optics to the next generation of nested shell astronomical X-ray space telescopes. A variety of deformable mirror technologies are currently available, the most promising of which for active X-ray mirrors are probably unimorph and bimorph piezoelectric mirrors. In this type of mirror one or more sheets of piezoelectric material are bonded to or coated with a passive reflective layer. On the back or between the piezoceramic layer/layers are series of electrodes. Application of an electric field causes the piezoelectric material to undergo local deformation thus changing the mirror shape. Starting in 2005 a proof of concept active mirror research program has been undertaken. This work included modelling and development of actively controlled thin shell mirrors. Finite element models of piezo-electric actuated mirrors have been developed and verified against experimental test systems. This has included the modelling and test of piezo-electric hexagonal unimorph segments. Various actuator types and low shrinkage conductive bonding methods have been investigated and laboratory tests of the use of piezo-electric actuators to adjust the form of an XMM-Newton space telescope engineering model mirror shell have been conducted and show that movement of the optics at the required level is achievable. Promising technological approaches have been identified including moulded piezo-ceramics and piezo-electrics fibre bundles.

  1. Investigations and experiments of a new multi-layer complex liquid-cooled mirror

    Institute of Scientific and Technical Information of China (English)

    Yuling Lu(陆宇灵); Zuhai Cheng(程祖海); Yaoning Zhang(张耀宁); Feng Sun(孙锋); Wenfeng Yu(余文峰)

    2004-01-01

    This paper describes a new multi-layer complex liquid-cooled Si mirror with 3 cooling ducts in Archimedes spirals. Utilizing the ANSYS program, the structure of the mirror is optimized and the thermal deformation model of the mirror is simulated. The simulation results show that the mirror has the following advantages:very small amount of surface deformation, uniform distribution of temperature and surface deformation,and fast surface shape restoration. The results of the experiments of thermal deformation and the surface restoration are accurately mapped to the simulation results.

  2. Communication Applications for Deformable Mirror Devices.

    Science.gov (United States)

    1997-06-01

    here labeled FBM, for flexure beam micromirror). (b) Example system for optical antenna aberration correction [after Gustafson. 1995] 1.3 General...micromirror array (here labeled FBM. for flexure beam micromirror), (b) Example system for optical antenna aberration correction [after Gustafson, 1995...Astronomical Telescope," Nature, Vol. 351, pp. 300-302. 23 May 1991. W. C. Brown. "Omi-directional Optical Antenna Element," U.S. Patent No. 5,033.833,23

  3. Double arch mirror study

    Science.gov (United States)

    Vukobratovich, D.; Hillman, D.

    1983-01-01

    The development of a method of mounting light weight glass mirrors for astronomical telescopes compatible with the goals of the Shuttle Infrared Telescope Facility (SIRTF) was investigated. A 20 in. diameter double arch lightweight mirror previously fabricated was modified to use a new mount configuration. This mount concept was developed and fabricated. The mounting concept of the double mounting mirror is outlined. The modifications made to the mirror, fabrication of the mirror mount, and room temperature testing of the mirror and mount and the extension of the mirror and mount concept to a full size (40 in. diameter) primary mirror for SIRTF are discussed.

  4. Ground-based observations of Kepler asteroseismic targets

    CERN Document Server

    Uytterhoeven, K; Southworth, J; Randall, S; Ostensen, R; Molenda-Zakowicz, J; Marconi, M; Kurtz, D W; Kiss, L; Gutierrez-Soto, J; Frandsen, S; De Cat, P; Bruntt, H; Briquet, M; Zhang, X B; Telting, J H; Steslicki, M; Ripepi, V; Pigulski, A; Paparo, M; Oreiro, R; Choong, Ngeow Chow; Niemczura, E; Nemec, J; Narwid, A; Mathias, P; Martin-Ruiz, S; Lehman, H; Kopacki, G; Karoff, C; Jackiewicz, J; Henden, A A; Handler, G; Grigachene, A; Green, E M; Garrido, R; Machado, L Fox; Debosscher, J; Creevey, O L; Catanzaro, G; Bognar, Z; Biazzo, K; Bernabei, S

    2010-01-01

    We present the ground-based activities within the different working groups of the Kepler Asteroseismic Science Consortium (KASC). The activities aim at the systematic characterization of the 5000+ KASC targets, and at the collection of ground-based follow-up time-series data of selected promising Kepler pulsators. So far, 35 different instruments at 30 telescopes on 22 different observatories in 12 countries are in use, and a total of more than 530 observing nights has been awarded. (Based on observations made with the Isaac Newton Telescope, William Herschel Telescope, Nordic Optical Telescope, Telescopio Nazionale Galileo, Mercator Telescope (La Palma, Spain), and IAC-80 (Tenerife, Spain). Also based on observations taken at the observatories of Sierra Nevada, San Pedro Martir, Vienna, Xinglong, Apache Point, Lulin, Tautenburg, Loiano, Serra la Nave, Asiago, McDonald, Skinakas, Pic du Midi, Mauna Kea, Steward Observatory, Bialkow Observatory of the Wroclaw University, Piszkesteto Mountain Station, Observato...

  5. Ground-based Nuclear Detonation Detection (GNDD) Technology Roadmap

    Energy Technology Data Exchange (ETDEWEB)

    Casey, Leslie A.

    2014-01-13

    This GNDD Technology Roadmap is intended to provide guidance to potential researchers and help management define research priorities to achieve technology advancements for ground-based nuclear explosion monitoring science being pursued by the Ground-based Nuclear Detonation Detection (GNDD) Team within the Office of Nuclear Detonation Detection in the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy (DOE). Four science-based elements were selected to encompass the entire scope of nuclear monitoring research and development (R&D) necessary to facilitate breakthrough scientific results, as well as deliver impactful products. Promising future R&D is delineated including dual use associated with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Important research themes as well as associated metrics are identified along with a progression of accomplishments, represented by a selected bibliography, that are precursors to major improvements to nuclear explosion monitoring.

  6. Ground-Based Calibration Of A Microwave Landing System

    Science.gov (United States)

    Kiriazes, John J.; Scott, Marshall M., Jr.; Willis, Alfred D.; Erdogan, Temel; Reyes, Rolando

    1996-01-01

    System of microwave instrumentation and data-processing equipment developed to enable ground-based calibration of microwave scanning-beam landing system (MSBLS) at distances of about 500 to 1,000 ft from MSBLS transmitting antenna. Ensures accuracy of MSBLS near touchdown point, without having to resort to expense and complex logistics of aircraft-based testing. Modified versions prove useful in calibrating aircraft instrument landing systems.

  7. Fabrication of Electrostatically Actuated MEMS Deformable Mirror with Continuous Surface%静电驱动连续面形微机电系统变形镜的制作

    Institute of Scientific and Technical Information of China (English)

    胡放荣; 马文英; 汪为民

    2011-01-01

    Based on a three-layer polysilicon surface micromachining process and some experience formulas of adaptive optics, an electrostatically actuated microelectromechanical systems (MEMS) deformable mirror (DM) with 16 actuators and continuous surface is designed and fabricated. Both static and dynamic characteristics of the prototype are tested using a scanning white light interferometer ZygoNewView7300. The result from the static test shows that the displacement of the actuator is 0. 667 jim at 150 V, the interaction between the neighboring actuator is 9% , and the position repeatability of the surface of DM is 10%. At the same time, the result from the dynamic test shows that the response time of the prototype is less than 30 fis and a cosine curve is observed under a sine driving signal. The resonance frequency of the actuator is about 36 kHz. This type of DM can be used for free space optical communication, laser beam shaping, wavefront correction, projection, biomedical imaging and human eye aberration correction.%基于三层多晶硅表面加工工艺和自适应光学经验公式,设计并制作了一种静电驱动的16单元连续面形微机电系统(MEMS)变形镜(DM),并用ZygoNewView7300白光干涉仪对样片的静态特性和动态响应特性进行了测试.静态测试结果表明,器件在150 V电压下的最大形变量为0.667 μm,相邻单元之间的交联值为9%,镜面位置重复性为10%.动态测试结果表明,器件对正弦驱动信号的响应时间小于30μs,响应曲线近似为一条余弦曲线,谐振频率为36 kHz.该变形镜可用于自由空间光通信、激光光束整形、波前畸变校正、投影显示、生物医学成像和人眼视差校正等重要领域.

  8. Ground-Based Lidar for Atmospheric Boundary Layer Ozone Measurements

    Science.gov (United States)

    Kuang, Shi; Newchurch, Michael J.; Burris, John; Liu, Xiong

    2013-01-01

    Ground-based lidars are suitable for long-term ozone monitoring as a complement to satellite and ozonesonde measurements. However, current ground-based lidars are unable to consistently measure ozone below 500 m above ground level (AGL) due to both engineering issues and high retrieval sensitivity to various measurement errors. In this paper, we present our instrument design, retrieval techniques, and preliminary results that focus on the high-temporal profiling of ozone within the atmospheric boundary layer (ABL) achieved by the addition of an inexpensive and compact mini-receiver to the previous system. For the first time, to the best of our knowledge, the lowest, consistently achievable observation height has been extended down to 125 m AGL for a ground-based ozone lidar system. Both the analysis and preliminary measurements demonstrate that this lidar measures ozone with a precision generally better than 10% at a temporal resolution of 10 min and a vertical resolution from 150 m at the bottom of the ABL to 550 m at the top. A measurement example from summertime shows that inhomogeneous ozone aloft was affected by both surface emissions and the evolution of ABL structures.

  9. Ground-based lidar for atmospheric boundary layer ozone measurements.

    Science.gov (United States)

    Kuang, Shi; Newchurch, Michael J; Burris, John; Liu, Xiong

    2013-05-20

    Ground-based lidars are suitable for long-term ozone monitoring as a complement to satellite and ozonesonde measurements. However, current ground-based lidars are unable to consistently measure ozone below 500 m above ground level (AGL) due to both engineering issues and high retrieval sensitivity to various measurement errors. In this paper, we present our instrument design, retrieval techniques, and preliminary results that focus on the high-temporal profiling of ozone within the atmospheric boundary layer (ABL) achieved by the addition of an inexpensive and compact mini-receiver to the previous system. For the first time, to the best of our knowledge, the lowest, consistently achievable observation height has been extended down to 125 m AGL for a ground-based ozone lidar system. Both the analysis and preliminary measurements demonstrate that this lidar measures ozone with a precision generally better than ±10% at a temporal resolution of 10 min and a vertical resolution from 150 m at the bottom of the ABL to 550 m at the top. A measurement example from summertime shows that inhomogeneous ozone aloft was affected by both surface emissions and the evolution of ABL structures.

  10. High Speed Magnetostrictive MEMS Actuated Mirror Deflectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The main goal of this proposal is to develop high speed magnetostrictive and MEMS actuators for rapidly deflecting or deforming mirrors. High speed, light-weight,...

  11. High Speed Magnetostrictive MEMS Actuated Mirror Deflectors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop high speed magnetostrictive and MEMS actuators for rapidly deflecting or deforming mirrors. High speed, light-weight, low voltage beam...

  12. Lightweight ZERODUR: Validation of Mirror Performance and Mirror Modeling Predictions

    Science.gov (United States)

    Hull, Tony; Stahl, H. Philip; Westerhoff, Thomas; Valente, Martin; Brooks, Thomas; Eng, Ron

    2017-01-01

    Upcoming spaceborne missions, both moderate and large in scale, require extreme dimensional stability while relying both upon established lightweight mirror materials, and also upon accurate modeling methods to predict performance under varying boundary conditions. We describe tests, recently performed at NASA's XRCF chambers and laboratories in Huntsville Alabama, during which a 1.2 m diameter, f/1.2988% lightweighted SCHOTT lightweighted ZERODUR(TradeMark) mirror was tested for thermal stability under static loads in steps down to 230K. Test results are compared to model predictions, based upon recently published data on ZERODUR(TradeMark). In addition to monitoring the mirror surface for thermal perturbations in XRCF Thermal Vacuum tests, static load gravity deformations have been measured and compared to model predictions. Also the Modal Response(dynamic disturbance) was measured and compared to model. We will discuss the fabrication approach and optomechanical design of the ZERODUR(TradeMark) mirror substrate by SCHOTT, its optical preparation for test by Arizona Optical Systems (AOS). Summarize the outcome of NASA's XRCF tests and model validations

  13. 镜像右位心及合并畸形彩色多普勒超声心动图特征和规律性研究%Atudy on Imaging Characteristics and Regularity of Color Doppler Echocardiography on Mirror Image Dextrocardia and Deformity

    Institute of Scientific and Technical Information of China (English)

    侯传举; 齐岩梅; 邓东安; 朱鲜阳; 韩秀敏; 卢迪

    2011-01-01

    Objective To explore the image characteristics and regularity of color Doppler echocardiography (CDE)on mirror image dextrocardia and deformity. Methods One hundred patients with mirror image dextrocardia and deformity were examined by CDE and the image characteristics and regularity of CDE were found. Ninety-five cases with mirror image dextrocardia and deformity underwent angiocardiography examination after CDE, Seventy-six cases were proved by surgical operations. Results Ninety-two cases were diagnosed correctly by the features of CDE imaging. The diagnostic rate of accuracy is 92 %,eight cases were misdiagnosed. The features in the mirrorimage dextrocardia and deformity CDE image characteristics and regularity were obvious. ① Mirror image dextrocardia usually combines twelve kinds congenital heart disease,among them, ILL type double outlet right ventricle(27 % )are common. IDD type corrected transposition of the great arteies( 17 % ),tetralogy of Fallot(16 % )and ventrcluar septal defect( 12 % )are not as common as the above. Double-inlet ventricle( 7 % ), tricuspid atresia( 5 % ), bilocular heart( 5 % ), ILL type complete transposition of the great arteies(4% ), mitral atresia(2 % ), isolated right ventricular outlet stenosis(2 % ), total anomalous pulmonary venous drainage( 2 % ), and isolated cleft mitral valve ( 1% ) are rare. ② Despite the diversity of combined congenital heart disease,all cases of adult mirror image dextrocardia have a common CDE characteristic of atria situs inversus. ③ adult mirror image dextrocardia combined double outlet right ventricle and complete transposition of the great arteies are left-transposition,combined corrected transposition of the great arteies are right-transposition.④ Mirror image dextrocardia combined pulmonary stenosis(80 % ) are common, pulmonary normal( 12 % ) and pulmonary hypertension(8%)are rare. ⑤ atral septal defect and ventricular septal defect color Doppler flow

  14. Optimum Design of Lightweight Silicon Carbide Mirror Assembly

    Institute of Scientific and Technical Information of China (English)

    HAN Yuanyuan; ZHANG Yumin; HAN Jiecai; ZHANG Jianhan; YAO Wang; ZHOU Yufeng

    2008-01-01

    According to the design requirement and on the basis of the principle that the thermal expansion coefficient of the support structure should match with that of the mirror, a lightweight silicon carbide primary mirror assembly was designed. Finite element analysis combined with the parameter-optimized method was used during the design. Lightweight cell and rigid rib structure were used for the mirror assembly. The static, dynamic and thermal properties of the primary mirror assembly were analyzed. It is shown that after optimization, the lightweight ratio of the silicon carbide mirror is 52.5%, and the rigidity of the silicon carbide structure is high enough to support the required mirror. When temperature changes, the deformation of the mirror surface is in proportion to the temperature difference.

  15. Augmenting WFIRST Microlensing with a Ground-Based Telescope Network

    Science.gov (United States)

    Zhu, Wei; Gould, Andrew

    2016-06-01

    Augmenting the Wide Field Infrared Survey Telescope (WFIRST) microlensing campaigns with intensive observations from a ground-based network of wide-field survey telescopes would have several major advantages. First, it would enable full two-dimensional (2-D) vector microlens parallax measurements for a substantial fraction of low-mass lenses as well as planetary and binary events that show caustic crossing features. For a significant fraction of the free-floating planet (FFP) events and all caustic-crossing planetary/binary events, these 2-D parallax measurements directly lead to complete solutions (mass, distance, transverse velocity) of the lens object (or lens system). For even more events, the complementary ground-based observations will yield 1-D parallax measurements. Together with the 1-D parallaxes from WFIRST alone, they can probe the entire mass range M > M_Earth. For luminous lenses, such 1-D parallax measurements can be promoted to complete solutions (mass, distance, transverse velocity) by high-resolution imaging. This would provide crucial information not only about the hosts of planets and other lenses, but also enable a much more precise Galactic model. Other benefits of such a survey include improved understanding of binaries (particularly with low mass primaries), and sensitivity to distant ice-giant and gas-giant companions of WFIRST lenses that cannot be detected by WFIRST itself due to its restricted observing windows. Existing ground-based microlensing surveys can be employed if WFIRST is pointed at lower-extinction fields than is currently envisaged. This would come at some cost to the event rate. Therefore the benefits of improved characterization of lenses must be weighed against these costs.

  16. The STACEE-32 Ground Based Gamma-ray Detector

    CERN Document Server

    Hanna, D S; Boone, L M; Chantell, M C; Conner, Z; Covault, C E; Dragovan, M; Fortin, P; Gregorich, D T; Hinton, J A; Mukherjee, R; Ong, R A; Oser, S; Ragan, K; Scalzo, R A; Schütte, D R; Theoret, C G; Tümer, T O; Williams, D A; Zweerink, J A

    2002-01-01

    We describe the design and performance of the Solar Tower Atmospheric Cherenkov Effect Experiment detector in its initial configuration (STACEE-32). STACEE is a new ground-based gamma ray detector using the atmospheric Cherenkov technique. In STACEE, the heliostats of a solar energy research array are used to collect and focus the Cherenkov photons produced in gamma-ray induced air showers. The large Cherenkov photon collection area of STACEE results in a gamma-ray energy threshold below that of previous detectors.

  17. The STACEE Ground-Based Gamma-Ray Detector

    CERN Document Server

    Gingrich, D M; Bramel, D; Carson, J; Covault, C E; Fortin, P; Hanna, D S; Hinton, J A; Jarvis, A; Kildea, J; Lindner, T; Müller, C; Mukherjee, R; Ong, R A; Ragan, K; Scalzo, R A; Theoret, C G; Williams, D A; Zweerink, J A

    2005-01-01

    We describe the design and performance of the Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) in its complete configuration. STACEE uses the heliostats of a solar energy research facility to collect and focus the Cherenkov photons produced in gamma-ray induced air showers. The light is concentrated onto an array of photomultiplier tubes located near the top of a tower. The large Cherenkov photon collection area of STACEE results in a gamma-ray energy threshold below that of previous ground-based detectors. STACEE is being used to observe pulsars, supernova remnants, active galactic nuclei, and gamma-ray bursts.

  18. Research on target accuracy for ground-based lidar

    Science.gov (United States)

    Zhu, Ling; Shi, Ruoming

    2009-05-01

    In ground based Lidar system, the targets are used in the process of registration, georeferencing for point cloud, and also can be used as check points. Generally, the accuracy of capturing the flat target center is influenced by scanning range and scanning angle. In this research, the experiments are designed to extract accuracy index of the target center with 0-90°scan angles and 100-195 meter scan ranges using a Leica HDS3000 laser scanner. The data of the experiments are listed in detail and the related results are analyzed.

  19. Mirror symmetry in the presence of branes

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, Adrian

    2011-10-11

    This work deals with mirror symmetry for N=1 compactifications on compact Calabi-Yau threefolds with branes. The mayor tool is a combined deformation space for the Calabi-Yau and a hypersurface within it. Periods of this deformation space contain information about B-type branes within the hypersurface in addition to the usual closed string data. To study these periods we generalize techniques used in closed string mirror symmetry. We derive the Picard-Fuchs system and encode the information in extended toric polytopes. Solutions of the Picard-Fuchs equations give superpotentials for certain brane configurations. This is an efficient way to calculate superpotentials. The deformations we consider are massive for all branes with non trivial superpotential. Depending on a choice of a family of hypersurfaces, the superpotential of the effective low energy theory depends on different massive fields. A priori there is no reason for these fields to be lighter then other fields that are not included. We find however examples where the superpotential is nearly at. In these examples we use the Gauss-Manin connection on the combined deformation space to define an open string mirror map. We find instanton generated superpotentials of A-type branes. This gives predictions for Ooguri-Vafa invariants counting holomorphic disks that end on a Lagrangian brane on the Quintic. A second class of examples does not have preferred nearly massless deformations and different families of hypersurfaces can be used to calculate the same on-shell superpotential. We calculate examples of superpotentials for branes in Calabi-Yau manifolds with several moduli. The on-shell superpotentials are mapped to the mirror A-model to study the instanton expansion and to obtain predictions for disk invariants. The combined deformation spaces are equivalent to the quantum corrected Kaehler deformation spaces of certain non compact Calabi-Yau fourfolds. These fourfolds are fibrations of Calabi-Yau threefolds

  20. Study on imaging characteristics of color Doppler echocardiography on adult mirror image dextrocardia and deformity%成人镜像右位心及合并畸形彩色多普勒超声心动图特征研究

    Institute of Scientific and Technical Information of China (English)

    侯传举; 邹苏娅; 邓东安; 朱鲜阳; 韩秀敏; 刘剑立; 胡斌; 王巧玲

    2011-01-01

    目的:探寻成人镜像右位心及合并畸形彩色多普勒超声心动图(CDE)特征.方法:应用CDE检查31例成人镜像右位心及合并畸形,寻找CDE特征,所有病例均经心导管对照,21例手术证实.结果:根据CDE特征对29例做出正确诊断,诊断准确率93.5%,误诊2例.成人镜像右位心及合并畸形CDE特征明显;①成人镜像右位心合并11种先天性心脏病,其中ILL型右心室双出口(22.6%)、IDD型矫正性大动脉转位(19.4%)和法乐四联症(19.4%)多见,心室双人口(12.9%)和室间隔缺损(6.5%)少见,两腔心、二尖瓣闭锁、三尖瓣闭锁、全肺静脉异位引流、孤立性双腔右心室和孤立性二尖瓣裂隙(各3.2%)更少见;②成人镜像右位心无论合并那种先天性心脏病均为心房反位;③成人镜像右位心合并右心室双出口大动脉均为左转位;合并矫正性大动脉转位大动脉均为右转位;(4)成人镜像右位心合并肺动脉狭窄(93.5%)多见,肺动脉高压(6.5%)少见.肺动脉狭窄时,彩色多普勒血流显像显示过肺动脉五彩镶嵌射流束血流信号;⑤合并房间隔缺损和室间隔缺损时,彩色多普勒血流显像显示过房间隔或室间隔左向右或双向五彩镶嵌分流束血流信号.结论:成人镜像右位心及合并畸形CDE特征明显,应用CDE对成人镜像右位心及合并畸形可做出正确诊断,但检查者必须熟练掌握本病解剖.在探查手法上与正常位心脏明显不同,检查前阅读X线正位胸片对CDE正确诊断有帮助,并可提高检查效率.%Objective:To explore the characteristics of color Doppler echocardiography (CDE) adult mirror image dextrocardia and deformiry. Methods Thirty-one patients with adult mirror image dextrocardia and deformity were examined by CDE. All cases with mirror image dextrocardia and deformity underwent angiocardiography examination after CDE, twenty-one cases were proved by surgical operations. Results: Twenty-nine cases were diagnosed

  1. Ground-Based Global Positioning System (GPS) Meteorology Integrated Precipitable Water Vapor (IPW)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Ground-Based Global Positioning System (GPS) Meteorology Integrated Precipitable Water Vapor (IPW) data set measures atmospheric water vapor using ground-based...

  2. Quality evaluation of spaceborne SiC mirrors (I): analytical examination of the effects on mirror accuracy by variation in the thermal expansion property of the mirror surface.

    Science.gov (United States)

    Kotani, Masaki; Imai, Tadashi; Katayama, Haruyoshi; Yui, Yukari; Tange, Yoshio; Kaneda, Hidehiro; Nakagawa, Takao; Enya, Keigo

    2013-07-10

    The Japan Aerospace Exploration Agency has studied a large-scale lightweight mirror constructed of reaction-bonded silicon carbide-based material as a key technology in future astronomical and earth observation missions. The authors selected silicon carbide as the promising candidate due to excellent characteristics of specific stiffness and thermal stability. One of the most important technical issues for large-scale ceramic components is the uniformity of the material's property, depending on part and processing. It might influence mirror accuracy due to uneven thermal deformation. The authors conducted systematic case studies for the conditions of CTE by finite element analysis to know the typical influence of material property nonuniformity on mirror accuracy and consequently derived a comprehensive empirical equation for the series of CTE's main factors. In addition, the authors computationally reproduced the mirror accuracy profile of a small prototype mirror shown in cryogenic testing and hereby verified wide-range practical computational evaluation technology of mirror accuracy.

  3. Statistical Studies of Ground-Based Optical Lightning Signatures

    Science.gov (United States)

    Hunt, C. R.; Nemzek, R. J.; Suszcynsky, D. M.

    2005-12-01

    Most extensive optical studies of lightning have been conducted from orbit, and the statistics of events collected from earth are relatively poorly documented. The time signatures of optical power measured in the presence of clouds are inevitably affected by scattering,which can distort the signatures by extending and delaying the amplitude profile in time. We have deployed two all-sky photodiode detectors, one in New Mexico and one in Oklahoma, which are gathering data alongside electric field change monitors as part of the LANL EDOTX Great Plains Array. Preliminary results show that the photodiode is sensitive to approximately 50% or more of RF events detected at ranges of up to 30 km, and still has some sensitivity at ranges in excess of 60 km (distances determined by the EDOTX field-change array). The shapes of events within this range were assessed, with focus on rise time, width, peak power, and their correlation to corresponding electric field signatures, and these are being compared with published on-orbit and ground-based data. Initial findings suggest a mean characteristic width (ratio of total detected optical energy to peak power) of 291 +/- 12 microseconds and a mean delay between the RF signal peak and optical peak of 121 +/- 17 microseconds. These values fall between prior ground-based measurements of direct return stroke emissions, and scattering-dominated on-orbit measurements. This work will promote better understanding of the correspondence between radio and optical measurements of lightning.

  4. Detection of atmospheric Cherenkov radiation using solar heliostat mirrors

    CERN Document Server

    Ong, R A

    1996-01-01

    The gamma-ray energy region between 20 and 250 GeV is largely unexplored. Ground-based atmospheric Cherenkov detectors offer a possible way to explore this region, but large Cherenkov photon collection areas are needed to achieve low energy thresholds. This paper discusses the development of a Cherenkov detector using the heliostat mirrors of a solar power plant as the primary collector. As part of this development, we built a prototype detector consisting of four heliostat mirrors and used it to record atmospheric Cherenkov radiation produced in extensive air showers created by cosmic ray particles.

  5. Solar tower atmospheric Cherenkov effect experiment (STACEE) for ground based gamma ray astronomy

    Science.gov (United States)

    Bhattacharya, D.; Chantell, M. C.; Coppi, P.; Covault, C. E.; Dragovan, M.; Gregorich, D. T.; Hanna, D. S.; Mukherjee, R.; Ong, R. A.; Oser, S.; Ragan, K.; Tümer, O. T.; Williams, D. A.

    1997-05-01

    The STACEE experiment is being developed to study very high energy astrophysical gamma rays between 50 and 500 GeV. During the last few years this previously unexplored region has received much attention due to the detection of sources up to about 10 GeV by the EGRET instrument on board the CGRO. However, the paucity of detected sources at ~1 TeV indicates that fundamental processes working within these sources and/or in the intergalactic space are responsible for the cutoff in the photon spectra of the EGRET sources. The cutoff or the spectral change of these sources can be observed with ground-based Cherenkov detectors with a very low threshold. The use of large arrays of mirrors at solar power facilities is a promising way of lowering the threshold. Using this concept a series of tests were conducted at the National Solar Thermal Test Facility (NSTTF) at Sandia National Laboratories (Albuquerque, NM) with a full size prototype of the STACEE telescope system. The tests show that STACEE will be capable of meaningful exploration of the gamma-ray sky between 50 and 500 GeV with good sensitivity.

  6. Ground-based complex for checking the optical system

    Science.gov (United States)

    Grebenyuk, V.; Boreiko, V.; Dmitrotsa, A.; Gorbunov, N.; Khrenov, B.; Klimov, P.; Lavrova, M.; Popescu, E. M.; Sabirov, B.; Tkachenko, A.; Tkachev, L.; Volvach, A.; Yashin, I.

    2016-09-01

    The purpose TUS space experiment is to study cosmic rays of ultrahigh energies produced by extensive air showers from space. The concentrator is located on satellite, made in the form of the Fresnel mirror towards the earth's atmosphere, the focus of which is a photodetector. The angle of view of the mirror is ±4.5° that for a given height of the orbit corresponds to the area 80 × 80 km2 on ground. The ground complex consisting of a number of stations, to check the optical system of the experiment is created, (their location and the amount will be determined after the launch of the satellite based on its actual orbit).

  7. Mirror Neurons and Mirror-Touch Synesthesia.

    Science.gov (United States)

    Linkovski, Omer; Katzin, Naama; Salti, Moti

    2016-05-30

    Since mirror neurons were introduced to the neuroscientific community more than 20 years ago, they have become an elegant and intuitive account for different cognitive mechanisms (e.g., empathy, goal understanding) and conditions (e.g., autism spectrum disorders). Recently, mirror neurons were suggested to be the mechanism underlying a specific type of synesthesia. Mirror-touch synesthesia is a phenomenon in which individuals experience somatosensory sensations when seeing someone else being touched. Appealing as it is, careful delineation is required when applying this mechanism. Using the mirror-touch synesthesia case, we put forward theoretical and methodological issues that should be addressed before relying on the mirror-neurons account. © The Author(s) 2016.

  8. Ground based interferometric radar initial look at Longview, Blue Springs, Tuttle Creek, and Milford Dams

    Science.gov (United States)

    Deng, Huazeng

    Measuring millimeter and smaller deformation has been demonstrated in the literature using RADAR. To address in part the limitations in current commercial satellite-based SAR datasets, a University of Missouri (MU) team worked with GAMMA Remote Sensing to develop a specialized (dual-frequency, polarimetric, and interferometric) ground-based real-aperture RADAR (GBIR) instrument. The GBIR device is portable with its tripod system and control electronics. It can be deployed to obtain data with high spatial resolution (i.e. on the order of 1 meter) and high temporal resolution (i.e. on the order 1 minute). The high temporal resolution is well suited for measurements of rapid deformation. From the same geodetic position, the GBIR may collect dual frequency data set using C-band and Ku-band. The overall goal of this project is to measure the deformation from various scenarios by applying the GBIR system. Initial efforts have been focusing on testing the system performance on different types of targets. This thesis details a number of my efforts on experimental and processing activities at the start of the MU GBIR imaging project. For improved close range capability, a wideband dual polarized antenna option was produced and tested. For GBIR calibration, several trihedral corner reflectors were designed and fabricated. In addition to experimental activities and site selection, I participated in advanced data processing activities. I processed GBIR data in several ways including single-look-complex (SLC) image generation, imagery registration, and interferometric processing. A number of initial-processed GBIR image products are presented from four dams: Longview, Blue Springs, Tuttle Creek, and Milford. Excellent imaging performance of the MU GBIR has been observed for various target types such as riprap, concrete, soil, rock, metal, and vegetation. Strong coherence of the test scene has been observed in the initial interferograms.

  9. Durable solar mirror films

    Energy Technology Data Exchange (ETDEWEB)

    O' Neill, Mark B.; Henderson, Andrew J.; Hebrink, Timothy J.; Katare, Rajesh K.; Jing, Naiyong; North, Diane; Peterson, Eric M.

    2017-02-14

    The present disclosure generally relates to durable solar mirror films, methods of making durable solar mirror films, and constructions including durable solar mirror films. In one embodiment, the present disclosure relates to a solar mirror film comprising: a multilayer optical film layer including having a coefficient of hygroscopic expansion of less than about 30 ppm per percent relative humidity; and a reflective layer having a coefficient of hygroscopic expansion.

  10. The Mirror Oscilloscpoe

    NARCIS (Netherlands)

    Goudriaan, B.

    2003-01-01

    This project is about designing and realizing an oscilloscope based on a laser beam reflected by two mirrors. The ¿Mirror Oscilloscope¿ uses two voice-coils actuators with mounted mirrors to reflect laser light, such that an image of a harmonic signal is projected on a projection screen. For trackin

  11. Atmospheric contamination for CMB ground-based observations

    CERN Document Server

    Errard, J; Akiba, Y; Arnold, K; Atlas, M; Baccigalupi, C; Barron, D; Boettger, D; Borrill, J; Chapman, S; Chinone, Y; Cukierman, A; Delabrouille, J; Dobbs, M; Ducout, A; Elleflot, T; Fabbian, G; Feng, C; Feeney, S; Gilbert, A; Goeckner-Wald, N; Halverson, N W; Hasegawa, M; Hattori, K; Hazumi, M; Hill, C; Holzapfel, W L; Hori, Y; Inoue, Y; Jaehnig, G C; Jaffe, A H; Jeong, O; Katayama, N; Kaufman, J; Keating, B; Kermish, Z; Keskitalo, R; Kisner, T; Jeune, M Le; Lee, A T; Leitch, E M; Leon, D; Linder, E; Matsuda, F; Matsumura, T; Miller, N J; Myers, M J; Navaroli, M; Nishino, H; Okamura, T; Paar, H; Peloton, J; Poletti, D; Puglisi, G; Rebeiz, G; Reichardt, C L; Richards, P L; Ross, C; Rotermund, K M; Schenck, D E; Sherwin, B D; Siritanasak, P; Smecher, G; Stebor, N; Steinbach, B; Stompor, R; Suzuki, A; Tajima, O; Takakura, S; Tikhomirov, A; Tomaru, T; Whitehorn, N; Wilson, B; Yadav, A; Zahn, O

    2015-01-01

    Atmosphere is one of the most important noise sources for ground-based Cosmic Microwave Background (CMB) experiments. By increasing optical loading on the detectors, it amplifies their effective noise, while its fluctuations introduce spatial and temporal correlations between detected signals. We present a physically motivated 3d-model of the atmosphere total intensity emission in the millimeter and sub-millimeter wavelengths. We derive an analytical estimate for the correlation between detectors time-ordered data as a function of the instrument and survey design, as well as several atmospheric parameters such as wind, relative humidity, temperature and turbulence characteristics. Using numerical computation, we examine the effect of each physical parameter on the correlations in the time series of a given experiment. We then use a parametric-likelihood approach to validate the modeling and estimate atmosphere parameters from the POLARBEAR-I project first season data set. We compare our results to previous st...

  12. Observational Selection Effects with Ground-based Gravitational Wave Detectors

    CERN Document Server

    Chen, Hsin-Yu; Vitale, Salvatore; Holz, Daniel E; Katsavounidis, Erik

    2016-01-01

    Ground-based interferometers are not perfectly all-sky instruments, and it is important to account for their behavior when considering the distribution of detected events. In particular, the LIGO detectors are most sensitive to sources above North America and the Indian Ocean and, as the Earth rotates, the sensitive regions are swept across the sky. However, because the detectors do not acquire data uniformly over time, there is a net bias on detectable sources' right ascensions. Both LIGO detectors preferentially collect data during their local night; it is more than twice as likely to be local midnight than noon when both detectors are operating. We discuss these selection effects and how they impact LIGO's observations and electromagnetic follow-up. Beyond galactic foregrounds associated with seasonal variations, we find that equatorial observatories can access over $80\\%$ of the localization probability, while mid-latitudes will access closer to $70\\%$. Facilities located near the two LIGO sites can obser...

  13. Ground-based optical observation system for LEO objects

    Science.gov (United States)

    Yanagisawa, T.; Kurosaki, H.; Oda, H.; Tagawa, M.

    2015-08-01

    We propose a ground-based optical observation system for monitoring LEO objects, which uses numerous optical sensors to cover a vast region of the sky. Its potential in terms of detection and orbital determination were examined. About 30 cm LEO objects at 1000 km altitude are detectable using an 18 cm telescope, a CCD camera and the analysis software developed. Simulations and a test observation showed that two longitudinally separate observation sites with arrays of optical sensors can identify the same objects from numerous data sets and determine their orbits precisely. The proposed system may complement or replace the current radar observation system for monitoring LEO objects, like space-situation awareness, in the near future.

  14. Identification of rainy periods from ground based microwave radiometry

    Directory of Open Access Journals (Sweden)

    Ada Vittoria Bosisio

    2012-03-01

    Full Text Available In this paper the authors present the results of a study aiming at detecting rainy data in measurements collected by a dual band ground-based radiometer. The proposed criterion is based on the ratio of the brightness temperatures observed in the 20-30 GHz band without need of any ancillary information. A major result obtained from the probability density of the ratio computed over one month of data is the identification of threshold values between clear sky, cloudy sky and rainy sky, respectively. A linear fit performed by using radiometric data and concurrent rain gauge measurements shows a correlation coefficient equal to 0.56 between the temperature ratio and the observed precipitation.

  15. Optical vortex coronagraphs on ground-based telescopes

    CERN Document Server

    Jenkins, Charles

    2007-01-01

    The optical vortex coronagraph is potentially a remarkably effective device, at least for an ideal unobstructed telescope. Most ground-based telescopes however suffer from central obscuration and also have to operate through the aberrations of the turbulent atmosphere. This note analyzes the performance of the optical vortex in these circumstances and compares to some other designs, showing that it performs similarly in this situation. There is a large class of coronagraphs of this general type, and choosing between them in particular applications depends on details of performance at small off-axis distances and uniformity of response in the focal plane. Issues of manufacturability to the necessary tolerances are also likely to be important.

  16. Observational Selection Effects with Ground-based Gravitational Wave Detectors

    Science.gov (United States)

    Chen, Hsin-Yu; Essick, Reed; Vitale, Salvatore; Holz, Daniel; Katsavounidis, Erik

    2017-01-01

    Ground-based interferometers are not perfectly all-sky instruments, and it is important to account for their behavior when considering the distribution of detected events. In particular, the LIGO detectors are most sensitive to sources above North America and the Indian Ocean and, as the Earth rotates, the sensitive regions are swept across the sky. However, because the detectors do not acquire data uniformly over time, there is a net bias on detectable sources' right ascensions. Both LIGO detectors preferentially collect data during their local night; it is more than twice as likely to be local midnight than noon when both detectors are operating. We discuss these selection effects and how they impact LIGO's observations and electromagnetic follow-up. These effects can inform electromagnetic follow-up activities and optimization, including the possibility of directing observations even before gravitational-wave events occur.

  17. Unique cell culture systems for ground based research

    Science.gov (United States)

    Lewis, Marian L.

    1990-01-01

    The horizontally rotating fluid-filled, membrane oxygenated bioreactors developed at NASA Johnson for spacecraft applications provide a powerful tool for ground-based research. Three-dimensional aggregates formed by cells cultured on microcarrier beads are useful for study of cell-cell interactions and tissue development. By comparing electron micrographs of plant seedlings germinated during Shuttle flight 61-C and in an earth-based rotating bioreactor it is shown that some effects of microgravity are mimicked. Bioreactors used in the UAH Bioreactor Laboratory will make it possible to determine some of the effects of altered gravity at the cellular level. Bioreactors can be valuable for performing critical, preliminary-to-spaceflight experiments as well as medical investigations such as in vitro tumor cell growth and chemotherapeutic drug response; the enrichment of stem cells from bone marrow; and the effect of altered gravity on bone and muscle cell growth and function and immune response depression.

  18. Spatial-angular modeling of ground-based biaxial lidar

    Science.gov (United States)

    Agishev, Ravil R.

    1997-10-01

    Results of spatial-angular LIDAR modeling based on an efficiency criterion introduced are represented. Their analysis shows that a low spatial-angular efficiency of traditional VIS and NIR systems is a main cause of a low S/BR ratio at the photodetector input. It determines the considerable measurements errors and the following low accuracy of atmospheric optical parameters retrieval. As we have shown, the most effective protection against intensive sky background radiation for ground-based biaxial LIDAR's consist in forming of their angular field according to spatial-angular efficiency criterion G. Some effective approaches to high G-parameter value achievement to achieve the receiving system optimization are discussed.

  19. ZERODUR for stress mirror polishing

    Science.gov (United States)

    Jedamzik, Ralf; Kunisch, Clemens; Westerhoff, Thomas

    2011-09-01

    Stress mirror polishing is considered as one of several polishing technologies for the generation of the aspherical shaped primary mirror segments of the thirty meter telescope (TMT). For stress mirror polishing it is essential to precisely know the elastic response of glass ceramic substrate materials under a given deformation load. In the past it was experimentally shown that glass ceramics do not respond instantaneously to loading and unloading conditions, this effect was called "delayed elasticity." Recently SCHOTT has shown that it is possible to use a model to predict the characteristic thermal expansion behaviour of individual ZERODUR® batches for a given temperature profile. A similar approach will be used to predict the delayed elastic behavior of ZERODUR® under time dependent loads. In this presentation the delayed elasticity effect of ZERODUR® is reviewed. The delayed elastic response of the material to load conditions is shown and discussed. First results of a model approach based on experimental results and tools that have been built up for the modelling of the delayed elasticity effect of ZERODUR® will be presented.

  20. Mirror Technology Roadmap for NASA's Exoplanet Exploration Program

    Science.gov (United States)

    Lawson, Peter R.; Shaklan, Stuart B.; Balasubramanian, K.

    2011-01-01

    There are several possible approaches to designing exoplanet missions: (1) Coronagraphs (2) Interferometers (3) Starshades Wavefront sensing and control is the central concern, not mirror size (1) Starlight suppression with deformable mirrors (2) Thermal and structural stability (3) Metrology for sensing and control Diffraction-limited optical primary mirrors 4-m or larger are needed to detect Earthlike planets (1) Surface figure similar to HST required (2) Smaller primary mirrors can be used with aggressive coronagraph designs, but the stability tolerances become the driving concern (3) Stability tolerances of coronagraphs are greatly reduced when larger primaries are used in conjunction with 8th-order masks Long term vision for large telescope development includes space-based segmented-mirror telescopes using actively-controlled glass segments or silicon carbide hybrid-mirror designs

  1. The 8.2 metre primary mirrors of the VLT

    Science.gov (United States)

    Dierickx, P.; Enard, D.; Merkle, F.; Noethe, L.; Wilson, R. N.

    1990-08-01

    The Very Large Telescope (VLT) presently being developed at ESO is described in terms of technological advances which make its use both technically effective and feasible. The VLT capitalizes on advances in materials, polishing techniques, and mirror support systems. The VLT consists of four 8-m alt-az telescopes and a 2-m auxiliary telescope in a single-dish configuration with Zerodur meniscus mirrors passively supported on a lateral system. A discussion of the tradeoffs between glass and metal mirrors is presented, and computerized polishing is described in relation to optical specifications. The mirror is supported with 150 axial and 60 lateral supports with electromechanical actuators to modulate applied force. The active optics concept is employed via the flexibility of the primary mirror, which generates elastomechanical deformations and the position and orientation of the secondary mirror.

  2. Water Cooled Mirror Design

    Energy Technology Data Exchange (ETDEWEB)

    Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Holloway, Michael Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pulliam, Elias Noel [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-30

    This design is intended to replace the current mirror setup being used for the NorthStar Moly 99 project in order to monitor the target coupon. The existing setup has limited movement for camera alignment and is difficult to align properly. This proposed conceptual design for a water cooled mirror will allow for greater thermal transfer between the mirror and the water block. It will also improve positioning of the mirror by using flexible vacuum hosing and a ball head joint capable of a wide range of motion. Incorporating this design into the target monitoring system will provide more efficient cooling of the mirror which will improve the amount of diffraction caused by the heating of the mirror. The process of aligning the mirror for accurate position will be greatly improved by increasing the range of motion by offering six degrees of freedom.

  3. Probing Pluto's Atmosphere Using Ground-Based Stellar Occultations

    Science.gov (United States)

    Sicardy, Bruno; Rio de Janeiro Occultation Team, Granada Team, International Occultation and Timing Association, Royal Astronomical Society New Zealand Occultation Section, Lucky Star associated Teams

    2016-10-01

    Over the last three decades, some twenty stellar occultations by Pluto have been monitored from Earth. They occur when the dwarf planet blocks the light from a star for a few minutes as it moves on the sky. Such events led to the hint of a Pluto's atmosphere in 1985, that was fully confirmed during another occultation in 1988, but it was only in 2002 that a new occultation could be recorded. From then on, the dwarf planet started to move in front of the galactic center, which amplified by a large factor the number of events observable per year.Pluto occultations are essentially refractive events during which the stellar rays are bent by the tenuous atmosphere, causing a gradual dimming of the star. This provides the density, pressure and temperature profiles of the atmosphere from a few kilometers above the surface up to about 250 km altitude, corresponding respectively to pressure levels of about 10 and 0.1 μbar. Moreover, the extremely fine spatial resolution (a few km) obtained through this technique allows the detection of atmospheric gravity waves, and permits in principle the detection of hazes, if present.Several aspects make Pluto stellar occultations quite special: first, they are the only way to probe Pluto's atmosphere in detail, as the dwarf planet is far too small on the sky and the atmosphere is far too tenuous to be directly imaged from Earth. Second, they are an excellent example of participative science, as many amateurs have been able to record those events worldwide with valuable scientific returns, in collaboration with professional astronomers. Third, they reveal Pluto's climatic changes on decade-scales and constrain the various seasonal models currently explored.Finally, those observations are fully complementary to space exploration, in particular with the New Horizons (NH) mission. I will show how ground-based occultations helped to better calibrate some NH profiles, and conversely, how NH results provide some key boundary conditions

  4. Independet Component Analyses of Ground-based Exoplanetary Transits

    Science.gov (United States)

    Silva Martins-Filho, Walter; Griffith, Caitlin Ann; Pearson, Kyle; Waldmann, Ingo; Biddle, Lauren; Zellem, Robert Thomas; Alvarez-Candal, Alvaro

    2016-10-01

    Most observations of exoplanetary atmospheres are conducted when a "Hot Jupiter" exoplanet transits in front of its host star. These Jovian-sized planets have small orbital periods, on the order of days, and therefore a short transit time, making them more ameanable to observations. Measurements of Hot Jupiter transits must achieve a 10-4 level of accuracy in the flux to determine the spectral modulations of the exoplanetary atmosphere. In order to accomplish this level of precision, we need to extract systematic errors, and, for ground-based measurements, the effects of Earth's atmosphere, from the signal due to the exoplanet, which is several orders of magnitudes smaller. Currently, the effects of the terrestrial atmosphere and the some of the time-dependent systematic errors are treated by dividing the host star by a reference star at each wavelength and time step of the transit. More recently, Independent Component Analyses (ICA) have been used to remove systematic effects from the raw data of space-based observations (Waldmann 2014,2012; Morello et al.,2015,2016). ICA is a statistical method born from the ideas of the blind-source separation studies, which can be used to de-trend several independent source signals of a data set (Hyvarinen and Oja, 2000). One strength of this method is that it requires no additional prior knowledge of the system. Here, we present a study of the application of ICA to ground-based transit observations of extrasolar planets, which are affected by Earth's atmosphere. We analyze photometric data of two extrasolar planets, WASP-1b and GJ3470b, recorded by the 61" Kuiper Telescope at Stewart Observatory using the Harris B and U filters. The presentation will compare the light curve depths and their dispersions as derived from the ICA analysis to those derived by analyses that ratio of the host star to nearby reference stars.References: Waldmann, I.P. 2012 ApJ, 747, 12, Waldamann, I. P. 2014 ApJ, 780, 23; Morello G. 2015 ApJ, 806

  5. a Compact Dial LIDAR for Ground-Based Ozone Atmospheric Profiling Measurements

    Science.gov (United States)

    De Young, R.; Carrion, W.; Pliutau, D.; Ganoe, R. E.

    2013-12-01

    A compact differential absorption lidar (DIAL) system has been developed at NASA Langley Research Center to provide ozone, aerosol and cloud atmospheric measurements in a mobile trailer for ground-based atmospheric ozone campaigns. This lidar will be integrated into the Air Quality lidar Network (AQLNet) currently made up of four other ozone lidars across the country. The lidar system consists of a UV and green laser transmitter, a telescope and an optical signal receiver box with associated Licel photon counting and analog channels. The laser transmitter consist of a Coherent Evolution 30 TEM00 1-kHz diode pumped Q-switched Nd:YLF inter-cavity doubled laser pumping a Ce:LiCAF tunable UV laser with all the associated power and lidar control support units on a single system rack. A custom-designed Ce:LiCAF tunable UV laser has a wavelength range of 282 to 300-nm that is selectable between two or more wavelengths. The current wavelengths are online 286.4 nm and offline 293.1 nm. The 527-nm visible beam is transmitted into the atmosphere for aerosol measurements. The fourth harmonic 262 nm beam is split by a beamsplitter into two pump beams that pump each face of the Ce:LiCAF crystal. A short laser cavity consisting of a 60% reflective (1m radius of curvature) output mirror, a dispersive prism and a flat HR mirror is used to produce the UV wavelengths. In order to produce different wavelengths, the high-reflectivity rear mirror is mounted on a servo controlled galvanometer motor to allow rapid tuning between the on and offline ozone wavelengths. Typical laser results are 6.8-W at 527-nm, 800-mW at 262-nm and 130-mW at the UV transmitted wavelengths. The lidar receiver system consists of a receiver telescope with a 40-cm diameter parabolic mirror. A fiber optic cable transmits the received signal from the telescope to the receiver box, which houses the detectors. A separate one inch diameter telescope with PMT and filter is used to sample the very near field to allow

  6. Observing Tsunamis in the Ionosphere Using Ground Based GPS Measurements

    Science.gov (United States)

    Galvan, D. A.; Komjathy, A.; Song, Y. Tony; Stephens, P.; Hickey, M. P.; Foster, J.

    2011-01-01

    Ground-based Global Positioning System (GPS) measurements of ionospheric Total Electron Content (TEC) show variations consistent with atmospheric internal gravity waves caused by ocean tsunamis following recent seismic events, including the Tohoku tsunami of March 11, 2011. We observe fluctuations correlated in time, space, and wave properties with this tsunami in TEC estimates processed using JPL's Global Ionospheric Mapping Software. These TEC estimates were band-pass filtered to remove ionospheric TEC variations with periods outside the typical range of internal gravity waves caused by tsunamis. Observable variations in TEC appear correlated with the Tohoku tsunami near the epicenter, at Hawaii, and near the west coast of North America. Disturbance magnitudes are 1-10% of the background TEC value. Observations near the epicenter are compared to estimates of expected tsunami-driven TEC variations produced by Embry Riddle Aeronautical University's Spectral Full Wave Model, an atmosphere-ionosphere coupling model, and found to be in good agreement. The potential exists to apply these detection techniques to real-time GPS TEC data, providing estimates of tsunami speed and amplitude that may be useful for future early warning systems.

  7. Tissue Engineering of Cartilage on Ground-Based Facilities

    Science.gov (United States)

    Aleshcheva, Ganna; Bauer, Johann; Hemmersbach, Ruth; Egli, Marcel; Wehland, Markus; Grimm, Daniela

    2016-06-01

    Investigations under simulated microgravity offer the opportunity for a better understanding of the influence of altered gravity on cells and the scaffold-free three-dimensional (3D) tissue formation. To investigate the short-term influence, human chondrocytes were cultivated for 2 h, 4 h, 16 h, and 24 h on a 2D Fast-Rotating Clinostat (FRC) in DMEM/F-12 medium supplemented with 10 % FCS. We detected holes in the vimentin network, perinuclear accumulations of vimentin after 2 h, and changes in the chondrocytes shape visualised by F-actin staining after 4 h of FRC-exposure. Scaffold-free cultivation of chondrocytes for 7 d on the Random Positioning Machine (RPM), the FRC and the Rotating Wall Vessel (RWV) resulted in spheroid formation, a phenomenon already known from spaceflight experiments with chondrocytes (MIR Space Station) and thyroid cancer cells (SimBox/Shenzhou-8 space mission). The experiments enabled by the ESA-CORA-GBF programme gave us an optimal opportunity to study gravity-related cellular processes, validate ground-based facilities for our chosen cell system, and prepare long-term experiments under real microgravity conditions in space

  8. Theoretical validation of ground-based microwave ozone observations

    Directory of Open Access Journals (Sweden)

    P. Ricaud

    Full Text Available Ground-based microwave measurements of the diurnal and seasonal variations of ozoneat 42±4.5 and 55±8 km are validated by comparing with results from a zero-dimensional photochemical model and a two-dimensional (2D chemical/radiative/dynamical model, respectively. O3 diurnal amplitudes measured in Bordeaux are shown to be in agreement with theory to within 5%. For the seasonal analysis of O3 variation, at 42±4.5 km, the 2D model underestimates the yearly averaged ozone concentration compared with the measurements. A double maximum oscillation (~3.5% is measured in Bordeaux with an extended maximum in September and a maximum in February, whilst the 2D model predicts only a single large maximum (17% in August and a pronounced minimum in January. Evidence suggests that dynamical transport causes the winter O3 maximum by propagation of planetary waves, phenomena which are not explicitly reproduced by the 2D model. At 55±8 km, the modeled yearly averaged O3 concentration is in very good agreement with the measured yearly average. A strong annual oscillation is both measured and modeled with differences in the amplitude shown to be exclusively linked to temperature fields.

  9. Models of ionospheric VLF absorption of powerful ground based transmitters

    Science.gov (United States)

    Cohen, M. B.; Lehtinen, N. G.; Inan, U. S.

    2012-12-01

    Ground based Very Low Frequency (VLF, 3-30 kHz) radio transmitters play a role in precipitation of energetic Van Allen electrons. Initial analyses of the contribution of VLF transmitters to radiation belt losses were based on early models of trans-ionospheric propagation known as the Helliwell absorption curves, but some recent studies have found that the model overestimates (by 20-100 dB) the VLF energy reaching the magnetosphere. It was subsequently suggested that conversion of wave energy into electrostatic modes may be responsible for the error. We utilize a newly available extensive record of VLF transmitter energy reaching the magnetosphere, taken from the DEMETER satellite, and perform a direct comparison with a sophisticated full wave model of trans-ionospheric propagation. Although the model does not include the effect of ionospheric irregularities, it correctly predicts the average total power injected into the magnetosphere within several dB. The results, particularly at nighttime, appear to be robust against the variability of the ionospheric electron density. We conclude that the global effect of irregularity scattering on whistler mode conversion to quasi-electrostatic may be no larger than 6 dB.

  10. Atmospheric Refraction Path Integrals in Ground-Based Interferometry

    CERN Document Server

    Mathar, R J

    2004-01-01

    The basic effect of the earth's atmospheric refraction on telescope operation is the reduction of the true zenith angle to the apparent zenith angle, associated with prismatic aberrations due to the dispersion in air. If one attempts coherent superposition of star images in ground-based interferometry, one is in addition interested in the optical path length associated with the refracted rays. In a model of a flat earth, the optical path difference between these is not concerned as the translational symmetry of the setup means no net effect remains. Here, I evaluate these interferometric integrals in the more realistic arrangement of two telescopes located on the surface of a common earth sphere and point to a star through an atmosphere which also possesses spherical symmetry. Some focus is put on working out series expansions in terms of the small ratio of the baseline over the earth radius, which allows to bypass some numerics which otherwise is challenged by strong cancellation effects in building the opti...

  11. Experiments on a Ground-Based Tomographic Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Hoonyol Lee

    2016-08-01

    Full Text Available This paper presents the development and experiment of three-dimensional image formation by using a ground-based tomographic synthetic aperture radar (GB-TomoSAR system. GB-TomoSAR formulates two-dimensional synthetic aperture by the motion of antennae, both in azimuth and vertical directions. After range compression, three-dimensional image focusing is performed by applying Deramp-FFT (Fast Fourier Transform algorithms, both in azimuth and vertical directions. Geometric and radiometric calibrations were applied to make an image cube, which is then projected into range-azimuth and range-vertical cross-sections for visualization. An experiment with a C-band GB-TomoSAR system with a scan length of 2.49 m and 1.86 m in azimuth and vertical-direction, respectively, shows distinctive three-dimensional radar backscattering of stable buildings and roads with resolutions similar to the theoretical values. Unstable objects such as trees and moving cars generate severe noise due to decorrelation during the eight-hour image-acquisition time.

  12. A comparative study of satellite and ground-based phenology.

    Science.gov (United States)

    Studer, S; Stöckli, R; Appenzeller, C; Vidale, P L

    2007-05-01

    Long time series of ground-based plant phenology, as well as more than two decades of satellite-derived phenological metrics, are currently available to assess the impacts of climate variability and trends on terrestrial vegetation. Traditional plant phenology provides very accurate information on individual plant species, but with limited spatial coverage. Satellite phenology allows monitoring of terrestrial vegetation on a global scale and provides an integrative view at the landscape level. Linking the strengths of both methodologies has high potential value for climate impact studies. We compared a multispecies index from ground-observed spring phases with two types (maximum slope and threshold approach) of satellite-derived start-of-season (SOS) metrics. We focus on Switzerland from 1982 to 2001 and show that temporal and spatial variability of the multispecies index correspond well with the satellite-derived metrics. All phenological metrics correlate with temperature anomalies as expected. The slope approach proved to deviate strongly from the temporal development of the ground observations as well as from the threshold-defined SOS satellite measure. The slope spring indicator is considered to indicate a different stage in vegetation development and is therefore less suited as a SOS parameter for comparative studies in relation to ground-observed phenology. Satellite-derived metrics are, however, very susceptible to snow cover, and it is suggested that this snow cover should be better accounted for by the use of newer satellite sensors.

  13. Satellite Type Estination from Ground-based Photometric Observation

    Science.gov (United States)

    Endo, T.; Ono, H.; Suzuki, J.; Ando, T.; Takanezawa, T.

    2016-09-01

    The optical photometric observation is potentially a powerful tool for understanding of the Geostationary Earth Orbit (GEO) objects. At first, we measured in laboratory the surface reflectance of common satellite materials, for example, Multi-layer Insulation (MLI), mono-crystalline silicon cells, and Carbon Fiber Reinforced Plastic (CFRP). Next, we calculated visual magnitude of a satellite by simplified shape and albedo. In this calculation model, solar panels have dimensions of 2 by 8 meters, and the bus area is 2 meters squared with measured optical properties described above. Under these conditions, it clarified the brightness can change the range between 3 and 4 magnitudes in one night, but color index changes only from 1 to 2 magnitudes. Finally, we observed the color photometric data of several GEO satellites visible from Japan multiple times in August and September 2014. We obtained that light curves of GEO satellites recorded in the B and V bands (using Johnson filters) by a ground-base optical telescope. As a result, color index changed approximately from 0.5 to 1 magnitude in one night, and the order of magnitude was not changed in all cases. In this paper, we briefly discuss about satellite type estimation using the relation between brightness and color index obtained from the photometric observation.

  14. Ground-based measurements of UV Index (UVI at Helwan

    Directory of Open Access Journals (Sweden)

    H. Farouk

    2012-12-01

    Full Text Available On October 2010 UV Index (UVI ground-based measurements were carried out by weather station at solar laboratory in NRIAG. The daily variation has maximum values in spring and summer days, while minimum values in autumn and winter days. The low level of UVI between 2.55 and 2.825 was found in December, January and February. The moderate level of UVI between 3.075 and 5.6 was found in March, October and November. The high level of UVI between 6.7 and 7.65 was found in April, May and September. The very high level of UVI between 8 and 8.6 was found in June, July and August. High level of radiation over 6 months per year including 3 months with a very high level UVI. According to the equation {UVI=a[SZA]b} the UVI increases with decreasing SZA by 82% on a daily scale and 88% on a monthly scale. Helwan exposure to a high level of radiation over 6 months per year including 3 months with a very high level UVI, so it is advisable not to direct exposure to the sun from 11 am to 2:00 pm.

  15. Optical Properties of Relativistic Plasma Mirrors

    CERN Document Server

    Vincenti, H; Kahaly, S; Martin, Ph; Quéré, F

    2013-01-01

    The advent of ultrahigh-power femtosecond lasers creates a need for optical components suitable to handle ultrahigh light intensities. Due to the unavoidable laser-induced ionization of matter, these components will have to be based on a plasma medium. An archetype of such optical elements is a plasma mirror, created when an intense femtosecond laser pulse impinges on a solid target. It consists of a dense plasma, formed by the laser field itself, which specularly reflects the main part of the pulse. Plasma mirrors have major potential applications as active optical elements to manipulate the temporal and spatial properties of intense laser beams, in particular for the generation of intense attosecond pulses of light. We investigate the basic physics involved in the deformation of a plasma mirror resulting from the light pressure exerted by the ultraintense laser during reflection, by deriving a simple model of this fundamental process, which we validate both numerically and experimentally. The understanding ...

  16. Active optics and modified-Rumsey wide-field telescopes: MINITRUST demonstrators with vase- and tulip-form mirrors

    Science.gov (United States)

    Lemaître, Gérard R.; Montiel, Pierre; Joulié, Patrice; Dohlen, Kjetil; Lanzoni, Patrick

    2005-12-01

    Wide-field astronomy requires the development of larger aperture telescopes. The optical properties of a three-mirror modified-Rumsey design provide significant advantages when compared to other telescope designs: (i) at any wavelength, the design has a flat field and is anastigmatic; (ii) the system is extremely compact, i.e., it is almost four times shorter than a Schmidt. Compared to the equally compact flat-field Ritchey-Chrétien with a doublet-lens corrector, as developed for the Sloan digital sky survey - and which requires the polishing of six optical surfaces - the proposed modified-Rumsey design requires only a two-surface polishing and provides a better imaging quality. All the mirrors are spheroids of the hyperboloid type. Starting from the classical Rumsey design, it is shown that the use of all eight available free parameters allows the simultaneous aspherization of the primary and tertiary mirrors by active optics methods from a single deformable substrate. The continuity conditions between the primary and the tertiary hyperbolizations are achieved by an intermediate narrow ring of constant thickness that is not optically used. After the polishing of a double vase form in a spherical shape, the primary-tertiary hyperbolizations are achieved by in situ stressing. The tulip-form secondary is hyperbolized by stress polishing. Other active optics alternatives are possible for a space telescope. The modified-Rumsey design is of interest for developing large space- and ground-based survey telescopes in UV, visible, or IR ranges, such as currently demonstrated with the construction of identical telescopes MINITRUST-1 and -2, f/5 - 2° field of view. Double-pass optical tests show diffraction-limited images.

  17. Mirror seeing of the Antarctic survey telescope

    Institute of Scientific and Technical Information of China (English)

    ZHANG Kaiyuan; LI Zhengyang; YUAN Xiangyan; PEI Chong

    2014-01-01

    Site testing results indicate that Antarctic Dome A is an excellent ground-based astronomical site suitable for observations ranging from visible to infrared wavelengths. However, the harsh environment in Antarctica, especially the very low temperature and atmospheric pressure, always produces frost on the telescopes’ mirrors, which are exposed to the air. Since the Dome A site is still unattended, the Antarctic telescope tubes are always designed to be filled with dry nitrogen, and the outer surfaces of the optical system are heated by an indium-tin oxide thin film. These precautions can prevent the optical surfaces from frosting over, but they degrade the image quality by introducing additional mirror seeing. Based on testing observations of the second Antarctic Survey Telescope (AST3-2) in the Mohe site in China, mirror seeing resulting from the heated aspheric plate has been measured using micro-thermal sensors. Results comparing the real-time atmospheric seeing monitored by the Differential Image Motion Monitor and real-time examinations of image quality agree well.

  18. Surface Figure Metrology for CELT Primary Mirror Segments

    Energy Technology Data Exchange (ETDEWEB)

    Sommargren, G; Phillion, D; Seppala, L; Lerner, S

    2001-02-27

    The University of California and California Institute of Technology are currently studying the feasibility of building a 30-m segmented ground based optical telescope called the California Extremely Large Telescope (CELT). The early ideas for this telescope were first described by Nelson and Mast and more recently refined by Nelson. In parallel, concepts for the fabrication of the primary segments were proposed by Mast, Nelson and Sommargren where high risk technologies were identified. One of these was the surface figure metrology needed for fabricating the aspheric mirror segments. This report addresses the advanced interferometry that will be needed to achieve 15nm rms accuracy for mirror segments with aspheric departures as large as 35mm peak-to-valley. For reasons of cost, size, measurement consistency and ease of operation we believe it is desirable to have a single interferometer that can be universally applied to each and every mirror segment. Such an instrument is described in this report.

  19. Relay Mirror Experiment overview: a GBL pointing and tracking demonstration

    Science.gov (United States)

    Dierks, Jeffrey S.; Ross, Susan E.; Brodsky, Aaron; Kervin, Paul W.; Holm, Richard W.

    1991-08-01

    The Relay Mirror Experiment (RME) has successfully demonstrated long-range, low-jitter tracking and pointing capabilities appropriate for ground-based laser (GBL) propagation. The RME program includes (1) a passively maneuverable, free-flying low-orbit spacecraft with a laser diode beacon and spoiled retroreflectors as acquisition aids; (2) a payload experiment package (PEP) consisting of sensors, optics, steerable mirrors, and control electronics. This subsystem accomplishes GBL tracking and pointing and the associated positioning of a space-based relay mirror sufficiently to relay an infrared beam between two ground sites. Design considerations for the control system included base motion disturbance and calibration; (3) two GBL sites each a tracking and pointing exercise in itself, using a combination of sensors and acquisition and tracking capabilities. One site includes a beam relay scoring capability.

  20. Radiometric modeling and calibration of the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) ground based measurement experiment

    Science.gov (United States)

    Tian, Jialin; Smith, William L.; Gazarik, Michael J.

    2008-12-01

    The ultimate remote sensing benefits of the high resolution Infrared radiance spectrometers will be realized with their geostationary satellite implementation in the form of imaging spectrometers. This will enable dynamic features of the atmosphere's thermodynamic fields and pollutant and greenhouse gas constituents to be observed for revolutionary improvements in weather forecasts and more accurate air quality and climate predictions. As an important step toward realizing this application objective, the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) Engineering Demonstration Unit (EDU) was successfully developed under the NASA New Millennium Program, 2000-2006. The GIFTS-EDU instrument employs three focal plane arrays (FPAs), which gather measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The GIFTS calibration is achieved using internal blackbody calibration references at ambient (260 K) and hot (286 K) temperatures. In this paper, we introduce a refined calibration technique that utilizes Principle Component (PC) analysis to compensate for instrument distortions and artifacts, therefore, enhancing the absolute calibration accuracy. This method is applied to data collected during the GIFTS Ground Based Measurement (GBM) experiment, together with simultaneous observations by the accurately calibrated AERI (Atmospheric Emitted Radiance Interferometer), both simultaneously zenith viewing the sky through the same external scene mirror at ten-minute intervals throughout a cloudless day at Logan Utah on September 13, 2006. The accurately calibrated GIFTS radiances are produced using the first four PC scores in the GIFTS-AERI regression model. Temperature and moisture profiles retrieved from the PC-calibrated GIFTS radiances are verified against radiosonde measurements collected throughout the GIFTS sky measurement period. Using the GIFTS GBM calibration model, we compute the calibrated radiances from data

  1. Manufacturing of Lightweight Mirror

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Fabrication of the lightweight mirror is one of the key techniques for many large optical systems. CAD,CAM and CNC technologies are adopted in designing and manufacturing such mirrors in CIOMP. Better working efficiency and higher lightweight grade have been achieved. The results show that mirrors up to 70% weight reduction and 0.02λ(rms.) surface accuracy or better can be obtained.

  2. Mirror Symmetry for Toric Branes on Compact Hypersurfaces

    CERN Document Server

    Alim, M; Mayr, P; Mertens, A

    2009-01-01

    We use toric geometry to study open string mirror symmetry on compact Calabi-Yau manifolds. For a mirror pair of toric branes on a mirror pair of toric hypersurfaces we derive a canonical hypergeometric system of differential equations, whose solutions determine the open/closed string mirror maps and the partition functions for spheres and discs. We define a linear sigma model for the brane geometry and describe a correspondence between dual toric polyhedra and toric brane geometries. The method is applied to study examples with obstructed and classically unobstructed brane moduli at various points in the deformation space. Computing the instanton expansion at large volume in the flat coordinates on the open/closed deformation space we obtain predictions for enumerative invariants.

  3. Nanoscale Deformable Optics

    Science.gov (United States)

    Strauss, Karl F.; Sheldon, Douglas J.

    2011-01-01

    Several missions and instruments in the conceptual design phase rely on the technique of interferometry to create detectable fringe patterns. The intimate emplacement of reflective material upon electron device cells based upon chalcogenide material technology permits high-speed, predictable deformation of the reflective surface to a subnanometer or finer resolution with a very high degree of accuracy. In this innovation, a layer of reflective material is deposited upon a wafer containing (perhaps in the millions) chalcogenic memory cells with the reflective material becoming the front surface of a mirror and the chalcogenic material becoming a means of selectively deforming the mirror by the application of heat to the chalcogenic material. By doing so, the mirror surface can deform anywhere from nil to nanometers in spots the size of a modern day memory cell, thereby permitting realtime tuning of mirror focus and reflectivity to mitigate aberrations caused elsewhere in the optical system. Modern foundry methods permit the design and manufacture of individual memory cells having an area of or equal to the Feature (F) size of the design (assume 65 nm). Fabrication rules and restraints generally require the instantiation of one memory cell to another no closer than 1.5 F, or, for this innovation, 90 nm from its neighbor in any direction. Chalcogenide is a semiconducting glass compound consisting of a combination of chalcogen ions, the ratios of which vary according to properties desired. It has been shown that the application of heat to cells of chalcogenic material cause a large alteration in resistance to the range of 4 orders of magnitude. It is this effect upon which chalcogenidebased commercial memories rely. Upon removal of the heat source, the chalcogenide rapidly cools and remains frozen in the excited state. It has also been shown that the chalcogenide expands in volume because of the applied heat, meaning that the coefficient of expansion of chalcogenic

  4. Observational Selection Effects with Ground-based Gravitational Wave Detectors

    Science.gov (United States)

    Chen, Hsin-Yu; Essick, Reed; Vitale, Salvatore; Holz, Daniel E.; Katsavounidis, Erik

    2017-01-01

    Ground-based interferometers are not perfect all-sky instruments, and it is important to account for their behavior when considering the distribution of detected events. In particular, the LIGO detectors are most sensitive to sources above North America and the Indian Ocean, and as the Earth rotates, the sensitive regions are swept across the sky. However, because the detectors do not acquire data uniformly over time, there is a net bias on detectable sources’ right ascensions. Both LIGO detectors preferentially collect data during their local night; it is more than twice as likely to be local midnight than noon when both detectors are operating. We discuss these selection effects and how they impact LIGO’s observations and electromagnetic (EM) follow-up. Beyond galactic foregrounds associated with seasonal variations, we find that equatorial observatories can access over 80% of the localization probability, while mid-latitudes will access closer to 70%. Facilities located near the two LIGO sites can observe sources closer to their zenith than their analogs in the south, but the average observation will still be no closer than 44° from zenith. We also find that observatories in Africa or the South Atlantic will wait systematically longer before they can begin observing compared to the rest of the world though, there is a preference for longitudes near the LIGOs. These effects, along with knowledge of the LIGO antenna pattern, can inform EM follow-up activities and optimization, including the possibility of directing observations even before gravitational-wave events occur.

  5. Ground-based Measurements of Next Generation Spectroradiometric Standard Stars

    Science.gov (United States)

    McGraw, John T.

    2013-01-01

    Accurate, radiometric standards are essential to the future of ground- and space-based astronomy and astrophysics. While astronomers tend to think of “standard stars” as available calibration sources, progress at NIST to accurately calibrate inexpensive, easy to use photodiode detectors as spectroradiometric standards from 200 nm to 1800 nm allows referencing astronomical measurements to these devices. Direction-, time-, and wavelength-dependent transmission of Earth’s atmosphere is the single largest source of error for ground-based radiometric measurement of astronomical objects. Measurements and impacts of atmospheric extinction - scattering and absorption - on imaging radiometric and spectroradiometric measurements are described. The conclusion is that accurate real-time measurement of extinction in the column of atmosphere through which standard star observations are made, over the spectral region being observed and over the field of view of the telescope are required. New techniques to directly and simultaneously measure extinction in the column of atmosphere through which observations are made are required. Our direct extinction measurement solution employs three small facility-class instruments working in parallel: a lidar to measure rapidly time variable transmission at three wavelengths with uncertainty of 0.25% per airmass, a spectrophotometer to measure rapidly wavelength variable extinction with sub-1% precision per nanometer resolution element from 350 to 1050nm, and a wide-field camera to measure angularly variable extinction over the field of view. These instruments and their operation will be described. We assert that application of atmospheric metadata provided by this instrument suite corrects for a significant fraction of systematic errors currently limiting radiometric precision, and provides a major step towards measurements that are provably dominated by random noise.

  6. Ozone profiles above Kiruna from two ground-based radiometers

    Science.gov (United States)

    Ryan, Niall J.; Walker, Kaley A.; Raffalski, Uwe; Kivi, Rigel; Gross, Jochen; Manney, Gloria L.

    2016-09-01

    This paper presents new atmospheric ozone concentration profiles retrieved from measurements made with two ground-based millimetre-wave radiometers in Kiruna, Sweden. The instruments are the Kiruna Microwave Radiometer (KIMRA) and the Millimeter wave Radiometer 2 (MIRA 2). The ozone concentration profiles are retrieved using an optimal estimation inversion technique, and they cover an altitude range of ˜ 16-54 km, with an altitude resolution of, at best, 8 km. The KIMRA and MIRA 2 measurements are compared to each other, to measurements from balloon-borne ozonesonde measurements at Sodankylä, Finland, and to measurements made by the Microwave Limb Sounder (MLS) aboard the Aura satellite. KIMRA has a correlation of 0.82, but shows a low bias, with respect to the ozonesonde data, and MIRA 2 shows a smaller magnitude low bias and a 0.98 correlation coefficient. Both radiometers are in general agreement with each other and with MLS data, showing high correlation coefficients, but there are differences between measurements that are not explained by random errors. An oscillatory bias with a peak of approximately ±1 ppmv is identified in the KIMRA ozone profiles over an altitude range of ˜ 18-35 km, and is believed to be due to baseline wave features that are present in the spectra. A time series analysis of KIMRA ozone for winters 2008-2013 shows the existence of a local wintertime minimum in the ozone profile above Kiruna. The measurements have been ongoing at Kiruna since 2002 and late 2012 for KIMRA and MIRA 2, respectively.

  7. Project management for complex ground-based instruments: MEGARA plan

    Science.gov (United States)

    García-Vargas, María. Luisa; Pérez-Calpena, Ana; Gil de Paz, Armando; Gallego, Jesús; Carrasco, Esperanza; Cedazo, Raquel; Iglesias, Jorge

    2014-08-01

    The project management of complex instruments for ground-based large telescopes is a challenge itself. A good management is a clue for project success in terms of performance, schedule and budget. Being on time has become a strict requirement for two reasons: to assure the arrival at the telescope due to the pressure on demanding new instrumentation for this first world-class telescopes and to not fall in over-costs. The budget and cash-flow is not always the expected one and has to be properly handled from different administrative departments at the funding centers worldwide distributed. The complexity of the organizations, the technological and scientific return to the Consortium partners and the participation in the project of all kind of professional centers working in astronomical instrumentation: universities, research centers, small and large private companies, workshops and providers, etc. make the project management strategy, and the tools and procedures tuned to the project needs, crucial for success. MEGARA (Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía) is a facility instrument of the 10.4m GTC (La Palma, Spain) working at optical wavelengths that provides both Integral-Field Unit (IFU) and Multi-Object Spectrograph (MOS) capabilities at resolutions in the range R=6,000-20,000. The project is an initiative led by Universidad Complutense de Madrid (Spain) in collaboration with INAOE (Mexico), IAA-CSIC (Spain) and Universidad Politécnica de Madrid (Spain). MEGARA is being developed under contract with GRANTECAN.

  8. Optical Performance Modeling of FUSE Telescope Mirror

    Science.gov (United States)

    Saha, Timo T.; Ohl, Raymond G.; Friedman, Scott D.; Moos, H. Warren

    2000-01-01

    We describe the Metrology Data Processor (METDAT), the Optical Surface Analysis Code (OSAC), and their application to the image evaluation of the Far Ultraviolet Spectroscopic Explorer (FUSE) mirrors. The FUSE instrument - designed and developed by the Johns Hopkins University and launched in June 1999 is an astrophysics satellite which provides high resolution spectra (lambda/Delta(lambda) = 20,000 - 25,000) in the wavelength region from 90.5 to 118.7 nm The FUSE instrument is comprised of four co-aligned, normal incidence, off-axis parabolic mirrors, four Rowland circle spectrograph channels with holographic gratings, and delay line microchannel plate detectors. The OSAC code provides a comprehensive analysis of optical system performance, including the effects of optical surface misalignments, low spatial frequency deformations described by discrete polynomial terms, mid- and high-spatial frequency deformations (surface roughness), and diffraction due to the finite size of the aperture. Both normal incidence (traditionally infrared, visible, and near ultraviolet mirror systems) and grazing incidence (x-ray mirror systems) systems can be analyzed. The code also properly accounts for reflectance losses on the mirror surfaces. Low frequency surface errors are described in OSAC by using Zernike polynomials for normal incidence mirrors and Legendre-Fourier polynomials for grazing incidence mirrors. The scatter analysis of the mirror is based on scalar scatter theory. The program accepts simple autocovariance (ACV) function models or power spectral density (PSD) models derived from mirror surface metrology data as input to the scatter calculation. The end product of the program is a user-defined pixel array containing the system Point Spread Function (PSF). The METDAT routine is used in conjunction with the OSAC program. This code reads in laboratory metrology data in a normalized format. The code then fits the data using Zernike polynomials for normal incidence

  9. Optomechanical design software for segmented mirrors

    Science.gov (United States)

    Marrero, Juan

    2016-08-01

    The software package presented in this paper, still under development, was born to help analyzing the influence of the many parameters involved in the design of a large segmented mirror telescope. In summary, it is a set of tools which were added to a common framework as they were needed. Great emphasis has been made on the graphical presentation, as scientific visualization nowadays cannot be conceived without the use of a helpful 3d environment, showing the analyzed system as close to reality as possible. Use of third party software packages is limited to ANSYS, which should be available in the system only if the FEM results are needed. Among the various functionalities of the software, the next ones are worth mentioning here: automatic 3d model construction of a segmented mirror from a set of parameters, geometric ray tracing, automatic 3d model construction of a telescope structure around the defined mirrors from a set of parameters, segmented mirror human access assessment, analysis of integration tolerances, assessment of segments collision, structural deformation under gravity and thermal variation, mirror support system analysis including warping harness mechanisms, etc.

  10. System Estimates Radius of Curvature of a Segmented Mirror

    Science.gov (United States)

    Rakoczy, John

    2008-01-01

    A system that estimates the global radius of curvature (GRoC) of a segmented telescope mirror has been developed for use as one of the subsystems of a larger system that exerts precise control over the displacements of the mirror segments. This GRoC-estimating system, when integrated into the overall control system along with a mirror-segment- actuation subsystem and edge sensors (sensors that measure displacements at selected points on the edges of the segments), makes it possible to control the GROC mirror-deformation mode, to which mode contemporary edge sensors are insufficiently sensitive. This system thus makes it possible to control the GRoC of the mirror with sufficient precision to obtain the best possible image quality and/or to impose a required wavefront correction on incoming or outgoing light. In its mathematical aspect, the system utilizes all the information available from the edge-sensor subsystem in a unique manner that yields estimates of all the states of the segmented mirror. The system does this by exploiting a special set of mirror boundary conditions and mirror influence functions in such a way as to sense displacements in degrees of freedom that would otherwise be unobservable by means of an edge-sensor subsystem, all without need to augment the edge-sensor system with additional metrological hardware. Moreover, the accuracy of the estimates increases with the number of mirror segments.

  11. Primary mirror assemblies for large space telescopes

    Science.gov (United States)

    Malamed, Evgeny R.; Sokolsky, M. N.

    1995-09-01

    In this report are considered the basic problems which relate to developemnt, manufacture, experimental trying out, and usage of primary mirrors (PM) of the large space telescopes intended to perform distant sounding of the Earth. Attention is concentrated on development of weight-reduced passive mirrors which ensure more reliable operation of the telescope as a whole. In the report we expressed the opinion that it is quite possible to manufacture a passive weight-reduced PM if its diameter is equal approximately to 3 m. Materials which may be used for the manufacturing of PM are beryllium and silicon carbide, physical and mechanical parameters of which are the most preferable ones. But it should be taken into consideration that this is the glass ceramic of CO115M brand which has been mastered by the industry of Russia in the greatest extent. It was confirmed that parameters of this material remain unchanged during a long period of time. Constructions of the PM, made of glass ceramic, as well as constructions of holders intended to fix the mirror, are presented in this report. A holder is used first of all to prevent lowering of a PM surface quality after a mirror has been removed from a machine and fixed in a primary mirror assembly (PMA). At present two-layer construction of a PM is preferable. This construction consists of thick base including weight reduction structure, which is in a radius which is optimum from the standpoint of deformation of a mirror operating surface. In the process of manufacture a mirror is deprived of its weight with the use of special pneumatic off-loading elements. PMA is erected in vertical plane by means of using an interferometric inspection system. In the end of this report we expressed the views on an approach to engineering of a PM by taking into account potentialities both of space ships and of carrier rockets.

  12. The mirror box

    Science.gov (United States)

    Thompson, Gene; Mathieson, Don

    2001-11-01

    The mirror box is an old standby in magic shows and an impressive demonstration of the law of reflection for the physics instructor. The box creates the illusion of an object floating in space by the use of a plane mirror.

  13. Corticospinal mirror neurons.

    Science.gov (United States)

    Kraskov, A; Philipp, R; Waldert, S; Vigneswaran, G; Quallo, M M; Lemon, R N

    2014-01-01

    Here, we report the properties of neurons with mirror-like characteristics that were identified as pyramidal tract neurons (PTNs) and recorded in the ventral premotor cortex (area F5) and primary motor cortex (M1) of three macaque monkeys. We analysed the neurons' discharge while the monkeys performed active grasp of either food or an object, and also while they observed an experimenter carrying out a similar range of grasps. A considerable proportion of tested PTNs showed clear mirror-like properties (52% F5 and 58% M1). Some PTNs exhibited 'classical' mirror neuron properties, increasing activity for both execution and observation, while others decreased their discharge during observation ('suppression mirror-neurons'). These experiments not only demonstrate the existence of PTNs as mirror neurons in M1, but also reveal some interesting differences between M1 and F5 mirror PTNs. Although observation-related changes in the discharge of PTNs must reach the spinal cord and will include some direct projections to motoneurons supplying grasping muscles, there was no EMG activity in these muscles during action observation. We suggest that the mirror neuron system is involved in the withholding of unwanted movement during action observation. Mirror neurons are differentially recruited in the behaviour that switches rapidly between making your own movements and observing those of others.

  14. Advanced Mirror Technology Development

    Science.gov (United States)

    Stahl, H. Philip

    2017-01-01

    The Advanced Mirror Technology Development (AMTD) project matures critical technologies required to enable ultra-stable 4-m-or-larger monolithic or segmented ultraviolet, optical, and infrared (UVOIR) space telescope primary-mirror assemblies for general astrophysics and ultra-high-contrast observations of exoplanets.

  15. Ground Based Investigation of Electrostatic Accelerometer in HUST

    Science.gov (United States)

    Bai, Y.; Zhou, Z.

    2013-12-01

    High-precision electrostatic accelerometers with six degrees of freedom (DOF) acceleration measurement were successfully used in CHAMP, GRACE and GOCE missions which to measure the Earth's gravity field. In our group, space inertial sensor based on the capacitance transducer and electrostatic control technique has been investigated for test of equivalence principle (TEPO), searching non-Newtonian force in micrometer range, and satellite Earth's field recovery. The significant techniques of capacitive position sensor with the noise level at 2×10-7pF/Hz1/2 and the μV/Hz1/2 level electrostatic actuator are carried out and all the six servo loop controls by using a discrete PID algorithm are realized in a FPGA device. For testing on ground, in order to compensate one g earth's gravity, the fiber torsion pendulum facility is adopt to measure the parameters of the electrostatic controlled inertial sensor such as the resolution, and the electrostatic stiffness, the cross couple between different DOFs. A short distance and a simple double capsule equipment the valid duration about 0.5 second is set up in our lab for the free fall tests of the engineering model which can directly verify the function of six DOF control. Meanwhile, high voltage suspension method is also realized and preliminary results show that the horizontal axis of acceleration noise is about 10-8m/s2/Hz1/2 level which limited mainly by the seismic noise. Reference: [1] Fen Gao, Ze-Bing Zhou, Jun Luo, Feasibility for Testing the Equivalence Principle with Optical Readout in Space, Chin. Phys. Lett. 28(8) (2011) 080401. [2] Z. Zhu, Z. B. Zhou, L. Cai, Y. Z. Bai, J. Luo, Electrostatic gravity gradiometer design for the advanced GOCE mission, Adv. Sp. Res. 51 (2013) 2269-2276. [3] Z B Zhou, L Liu, H B Tu, Y Z Bai, J Luo, Seismic noise limit for ground-based performance measurements of an inertial sensor using a torsion balance, Class. Quantum Grav. 27 (2010) 175012. [4] H B Tu, Y Z Bai, Z B Zhou, L Liu, L

  16. Ground-Based Observing Campaign of Briz-M Debris

    Science.gov (United States)

    Lederer, S. M.; Buckalew, B.; Frith, J.; Cowardin, H. M.; Hickson, P.; Matney, M.; Anz-Meador, P.

    2017-01-01

    In 2015, NASA's Orbital Debris Program Office (ODPO) completed the installation of the Meter Class Autonomous Telescope (MCAT) on Ascension Island. MCAT is a 1.3m optical telescope designed with a fast tracking capability for observing orbital debris at all orbital regimes (Low-Erath orbits to Geosyncronous (GEO) orbits) from a low latitude site. This new asset is dedicated year-round for debris observations, and its location fills a geographical gap in the Ground-based Electro Optical Space Surveillance (GEODSS) network. A commercial off the shelf (COTS) research grade 0.4m telescope (named the Benbrook telescope) will also be installed on Ascension at the end of 2016. This smaller version is controlled by the same master software, designed by Euclid Research, and can be tasked to work independently or in concert with MCAT. Like MCAT, it has a the same suite of filters, a similar field of view, and a fast-tracking Astelco mount, and is also capable of tracking debris at all orbital regimes. These assets are well suited for targeted campagins or surveys of debris. Since 2013, NASA's ODPO has also had extensive access to the 3.8m infrared UKIRT telescope, located on Mauna Kea. At nearly 14,000-ft, this site affords excellent conditions for collecting both photometery and spectroscopy at near-IR (0.9 - 2.5 micrometers SWIR) and thermal-IR (8 - 25 micrometers; LWIR) regimes, ideal for investigating material properties as well as thermal characteristics and sizes of debris. For the purposes of understanding orbital debris, taking data in both survey mode as well as targeting individual objects for more in-depth characterizations are desired. With the recent break-ups of Briz-M rocket bodies, we have collected a suite of data in the optical, near-infrared, and mid-infrared of in-tact objects as well as those classified as debris. A break-up at GEO of a Briz-M rocket occurred in January, 2016, well timed for the first remote observing survey-campaign with MCAT. Access to

  17. Shifts in the eruptive styles at Stromboli in 2010–2014 revealed by ground-based InSAR data

    Science.gov (United States)

    Di Traglia, Federico; Battaglia, Maurizio; Nolesini, Teresa; Lagomarsino, Daniela; Casaglia, Nicola

    2015-01-01

    Ground-Based Interferometric Synthetic Aperture Radar (GBInSAR) is an efficient technique for capturing short, subtle episodes of conduit pressurization in open vent volcanoes like Stromboli (Italy), because it can detect very shallow magma storage, which is difficult to identify using other methods. This technique allows the user to choose the optimal radar location for measuring the most significant deformation signal, provides an exceptional geometrical resolution, and allows for continuous monitoring of the deformation. Here, we present and model ground displacements collected at Stromboli by GBInSAR from January 2010 to August 2014. During this period, the volcano experienced several episodes of intense volcanic activity, culminated in the effusive flank eruption of August 2014. Modelling of the deformation allowed us to estimate a source depth of 482 ± 46 m a.s.l. The cumulative volume change was 4.7 ± 2.6 × 105 m3. The strain energy of the source was evaluated 3–5 times higher than the surface energy needed to open the 6–7 August eruptive fissure. The analysis proposed here can help forecast shifts in the eruptive style and especially the onset of flank eruptions at Stromboli and at similar volcanic systems (e.g. Etna, Piton de La Fournaise, Kilauea).

  18. The potential of advanced ground-based gravitational wave detectors to detect generic deviations from general relativity

    Science.gov (United States)

    Narikawa, Tatsuya; Tagoshi, Hideyuki

    2016-09-01

    We discuss the potential of advanced ground-based gravitational wave detectors such as LIGO, Virgo, and KAGRA to detect generic deviations of gravitational waveforms from the predictions of general relativity. We use the parameterized post-Einsteinian formalism to characterize the deviations, and assess what magnitude of deviations are detectable by using an approximate decision scheme based on Bayesian statistics. We find that there exist detectable regions of the parameterized post-Einsteinian parameters for different binary masses from the observation of a single gravitational wave event. The regions are not excluded by currently existing binary pulsar observations for the parameterized post-Einsteinian parameters at higher post-Newtonian order. We also find that neglect of orbital eccentricity or tidal deformation effects do not cause a significant bias on the detectable region of generic deviations from general relativity.

  19. Comparison of Stress Relief Procedures for Cryogenic Aluminum Mirrors

    Science.gov (United States)

    Ohl, Raymond G.; Barthelmy, Michael P.; Zewari, S. Wahid; Toland, Ronald; Mink, Ronald; Mentzell, J. Eric; Greenhouse, Matthew A.; McMann, Joseph C.; Hylan, Jason; Hagopian, John G.; Krebs, Carolyn (Technical Monitor)

    2002-01-01

    The Infrared Multi-Object Spectrograph (IRMOS) is a facility instrument for the Kitt Peak National Observatory Mayall Telescope (3.8 meter) and an engineering prototype for a potential design for the Next Generation Space Telescope/Multi-Object Spectrograph. IRMOS is a low-to mid-resolution (R = lambda/delta-lambda = 300-3800), near-IR (0.8-2.5 micron) spectrograph which produces simultaneous spectra of approximately 100 objects in its 2.8 x 2.0 arcmin field of view using a commercial MEMS multimirror array device. The instrument operating temperature is 80 K and the design is athermal --- the optical bench and mirrors are machined from aluminum 6061-T651. In spite of its baseline mechanical stress relief, aluminum 6061-T651 harbors some residual stress, which, unless relieved during fabrication, may relieve and distort mirror figure to unacceptable levels at the operating temperature. Other cryogenic instruments using aluminum mirrors for both ground-based and space IR astronomy have employed a variety of heat treatment formulae, with mixed results. We present the results of a test program designed to empirically determine the best stress relief procedure for the IRMOS mirrors. Identical test mirrors with spherical and flat optical prescriptions are processed with five different heat treatment formulae from the literature and compared to samples with out any additional processing. After figuring via diamond turning, the mirrors are tested for figure error and radius of curvature at room temperature and at 80 K for several thermal cycles. The heat treatment procedure for the mirrors that yielded the least and most repeatable change in figure error and radius is applied to the IRMOS mirror blanks. We correlate the results of our optical testing with heat treatment and metallographic data.

  20. Sentinel-1 and ground-based sensors for a continuous monitoring of the Corvara landslide kinematic (South Tirol, Italy)

    Science.gov (United States)

    Schlögel, Romy; Darvishi, Mehdi; Cuozzo, Giovanni; Kofler, Christian; Rutzinger, Martin; Zieher, Thomas; Toschi, Isabella; Remondino, Fabio

    2017-04-01

    Sentinel-1 mission allows us to have Synthetic Aperture Radar (SAR) acquisitions over large areas every 6 days with spatial resolution of 20 m. This new open-source generation of satellites has enhanced the capabilities for continuously studying earth surface changes. Over the past two decades, several studies have demonstrated the potential of Differential Synthetic Aperture Radar Interferometry (DInSAR) for detecting and quantifying land surface deformation. DInSAR limitations and challenges are linked to the SAR properties and the field conditions (especially in Alpine environments) leading to spatial and temporal decorrelation of the SAR signal. High temporal decorrelation can be caused by changes in vegetation (particularly in non-urban areas), atmospheric conditions or high ground surface velocity. In this study, kinematics of the complex and vegetated Corvara landslide, situated in Val Badia (South Tirol, Italy), are monitored by a network of 3 permanent and 13 monthly Differential Global Positioning System (DGPS) stations. The slope displacement rates are found to be highly unsteady and reach several meters a year. This analysis focuses on evaluating the limitations of Sentinel-1 imagery processed with Small Baseline Subset (SBAS) technique in comparison to ground-based measurements for assessing the landslide kinematic linked to meteorological conditions. Selecting some particular acquisitions, coherence thresholds and unwrapping processes gives various results in terms of reliability and accuracy supporting the understanding of the landslide velocity field. The evolution of the coherence and phase signals are studied according to the changing field conditions and the monitored ground-based displacements. DInSAR deformation maps and residual topographic heights are finally compared with difference of high resolution Digital Elevation Models at local scale. This research is conducted within the project LEMONADE (http://lemonade.mountainresearch.at) funded

  1. Space Mirror Alignment System

    Science.gov (United States)

    Jau, Bruno M.; McKinney, Colin; Smythe, Robert F.; Palmer, Dean L.

    2011-01-01

    An optical alignment mirror mechanism (AMM) has been developed with angular positioning accuracy of +/-0.2 arcsec. This requires the mirror s linear positioning actuators to have positioning resolutions of +/-112 nm to enable the mirror to meet the angular tip/tilt accuracy requirement. Demonstrated capabilities are 0.1 arc-sec angular mirror positioning accuracy, which translates into linear positioning resolutions at the actuator of 50 nm. The mechanism consists of a structure with sets of cross-directional flexures that enable the mirror s tip and tilt motion, a mirror with its kinematic mount, and two linear actuators. An actuator comprises a brushless DC motor, a linear ball screw, and a piezoelectric brake that holds the mirror s position while the unit is unpowered. An interferometric linear position sensor senses the actuator s position. The AMMs were developed for an Astrometric Beam Combiner (ABC) optical bench, which is part of an interferometer development. Custom electronics were also developed to accommodate the presence of multiple AMMs within the ABC and provide a compact, all-in-one solution to power and control the AMMs.

  2. Ground-based monitoring of solar radiation in Moldova

    Science.gov (United States)

    Aculinin, Alexandr; Smicov, Vladimir

    2010-05-01

    Integrated measurements of solar radiation in Kishinev, Moldova have been started by Atmospheric Research Group (ARG) at the Institute of Applied Physics from 2003. Direct, diffuse and total components of solar and atmospheric long-wave radiation are measured by using of the radiometric complex at the ground-based solar radiation monitoring station. Measurements are fulfilled at the stationary and moving platforms equipped with the set of 9 broadband solar radiation sensors overlapping wavelength range from UV-B to IR. Detailed description of the station can be found at the site http://arg.phys.asm.md. Ground station is placed in an urban environment of Kishinev city (47.00N; 28.56E). Summary of observation data acquired at the station in the course of short-term period from 2004 to 2009 are presented below. Solar radiation measurements were fulfilled by using CM11(280-3000 nm) and CH1 sensors (Kipp&Zonen). In the course of a year maximum and minimum of monthly sums of total radiation was ~706.4 MJm-2 in June and ~82.1MJm-2 in December, respectively. Monthly sums of direct solar radiation (on horizontal plane) show the maximum and minimum values of the order ~456.9 MJm-2 in July and ~25.5MJm-2 in December, respectively. In an average, within a year should be marked the predominance of direct radiation over the scattered radiation, 51% and 49%, respectively. In the course of a year, the percentage contribution of the direct radiation into the total radiation is ~55-65% from May to September. In the remaining months, the percentage contribution decreases and takes the minimum value of ~ 28% in December. In an average, annual sum of total solar radiation is ~4679.9 MJm-2. For the period from April to September accounts for ~76% of the annual amount of total radiation. Annual sum of sunshine duration accounts for ~2149 hours, which is of ~ 48% from the possible sunshine duration. In an average, within a year maximum and minimum of sunshine duration is ~ 304 hours in

  3. Biosensors for EVA: Improved Instrumentation for Ground-based Studies

    Science.gov (United States)

    Soller, B.; Ellerby, G.; Zou, F.; Scott, P.; Jin, C.; Lee, S. M. C.; Coates, J.

    2010-01-01

    During lunar excursions in the EVA suit, real-time measurement of metabolic rate is required to manage consumables and guide activities to ensure safe return to the base. Metabolic rate, or oxygen consumption (VO2), is normally measured from pulmonary parameters but cannot be determined with standard techniques in the oxygen-rich environment of a spacesuit. Our group has developed novel near infrared spectroscopic (NIRS) methods to calculate muscle oxygen saturation (SmO 2), hematocrit, and pH, and we recently demonstrated that we can use our NIRS sensor to measure VO 2 on the leg during cycling. Our NSBRI project has 4 objectives: (1) increase the accuracy of the metabolic rate calculation through improved prediction of stroke volume; (2) investigate the relative contributions of calf and thigh oxygen consumption to metabolic rate calculation for walking and running; (3) demonstrate that the NIRS-based noninvasive metabolic rate methodology is sensitive enough to detect decrement in VO 2 in a space analog; and (4) improve instrumentation to allow testing within a spacesuit. Over the past year we have made progress on all four objectives, but the most significant progress was made in improving the instrumentation. The NIRS system currently in use at JSC is based on fiber optics technology. Optical fiber bundles are used to deliver light from a light source in the monitor to the patient, and light reflected back from the patient s muscle to the monitor for spectroscopic analysis. The fiber optic cables are large and fragile, and there is no way to get them in and out of the test spacesuit used for ground-based studies. With complimentary funding from the US Army, we undertook a complete redesign of the sensor and control electronics to build a novel system small enough to be used within the spacesuit and portable enough to be used by a combat medic. In the new system the filament lamp used in the fiber optic system was replaced with a novel broadband near infrared

  4. Biosensors for EVA: Improved Instrumentation for Ground-based Studies

    Science.gov (United States)

    Soller, B.; Ellerby, G.; Zou, F.; Scott, P.; Jin, C.; Lee, S. M. C.; Coates, J.

    2010-01-01

    During lunar excursions in the EVA suit, real-time measurement of metabolic rate is required to manage consumables and guide activities to ensure safe return to the base. Metabolic rate, or oxygen consumption (VO2), is normally measured from pulmonary parameters but cannot be determined with standard techniques in the oxygen-rich environment of a spacesuit. Our group has developed novel near infrared spectroscopic (NIRS) methods to calculate muscle oxygen saturation (SmO 2), hematocrit, and pH, and we recently demonstrated that we can use our NIRS sensor to measure VO 2 on the leg during cycling. Our NSBRI project has 4 objectives: (1) increase the accuracy of the metabolic rate calculation through improved prediction of stroke volume; (2) investigate the relative contributions of calf and thigh oxygen consumption to metabolic rate calculation for walking and running; (3) demonstrate that the NIRS-based noninvasive metabolic rate methodology is sensitive enough to detect decrement in VO 2 in a space analog; and (4) improve instrumentation to allow testing within a spacesuit. Over the past year we have made progress on all four objectives, but the most significant progress was made in improving the instrumentation. The NIRS system currently in use at JSC is based on fiber optics technology. Optical fiber bundles are used to deliver light from a light source in the monitor to the patient, and light reflected back from the patient s muscle to the monitor for spectroscopic analysis. The fiber optic cables are large and fragile, and there is no way to get them in and out of the test spacesuit used for ground-based studies. With complimentary funding from the US Army, we undertook a complete redesign of the sensor and control electronics to build a novel system small enough to be used within the spacesuit and portable enough to be used by a combat medic. In the new system the filament lamp used in the fiber optic system was replaced with a novel broadband near infrared

  5. Ground-based Space Weather Monitoring with LOFAR

    Science.gov (United States)

    Wise, Michael; van Haarlem, Michiel; Lawrence, Gareth; Reid, Simon; Bos, Andre; Rawlings, Steve; Salvini, Stef; Mitchell, Cathryn; Soleimani, Manuch; Amado, Sergio; Teresa, Vital

    As one of the first of a new generation of radio instruments, the International LOFAR Telescope (ILT) will provide a number of unique and novel capabilities for the astronomical community. These include remote configuration and operation, dynamic real-time processing and system response, and the ability to provide multiple simultaneous streams of data to a community whose scientific interests run the gamut from lighting in the atmospheres of distant planets to the origins of the universe itself. The LOFAR (LOw Frequency ARray) system is optimized for a frequency range from 30-240 MHz and consists of multiple antenna fields spread across Europe. In the Netherlands, a total 36 LOFAR stations are nearing completion with an initial 8 international stations currently being deployed in Germany, France, Sweden, and the UK. Digital beam-forming techniques make the LOFAR system agile and allow for rapid repointing of the telescope as well as the potential for multiple simultaneous observations. With its dense core array and long interferometric baselines, LOFAR has the potential to achieve unparalleled sensitivity and spatial resolution in the low frequency radio regime. LOFAR will also be one of the first radio observatories to feature automated processing pipelines to deliver fully calibrated science products to its user community. As we discuss in this presentation, the same capabilities that make LOFAR a powerful tool for radio astronomy also provide an excellent platform upon which to build a ground-based monitoring system for space weather events. For example, the ability to monitor Solar activity in near real-time is one of the key scientific capabilities being developed for LOFAR. With only a fraction of its total observing capacity, LOFAR will be able to provide continuous monitoring of the Solar spectrum over the entire 10-240 MHz band down to microsecond timescales. Autonomous routines will scan these incoming spectral data for evidence of Solar flares and be

  6. Mesmerising mirror neurons.

    Science.gov (United States)

    Heyes, Cecilia

    2010-06-01

    Mirror neurons have been hailed as the key to understanding social cognition. I argue that three currents of thought-relating to evolution, atomism and telepathy-have magnified the perceived importance of mirror neurons. When they are understood to be a product of associative learning, rather than an adaptation for social cognition, mirror neurons are no longer mesmerising, but they continue to raise important questions about both the psychology of science and the neural bases of social cognition. Copyright 2010 Elsevier Inc. All rights reserved.

  7. An empirical RBF model of the magnetosphere parameterized by interplanetary and ground-based drivers

    Science.gov (United States)

    Tsyganenko, N. A.; Andreeva, V. A.

    2016-11-01

    In our recent paper (Andreeva and Tsyganenko, 2016), a novel method was proposed to model the magnetosphere directly from spacecraft data, with no a priori knowledge nor ad hoc assumptions about the geometry of the magnetic field sources. The idea was to split the field into the toroidal and poloidal parts and then expand each part into a weighted sum of radial basis functions (RBF). In the present work we take the next step forward by having developed a full-fledged model of the near magnetosphere, based on a multiyear set of space magnetometer data (1995-2015) and driven by ground-based and interplanetary input parameters. The model consolidates the largest ever amount of data and has been found to provide the best ever merit parameters, in terms of both the overall RMS residual field and record-high correlation coefficients between the observed and model field components. By experimenting with different combinations of input parameters and their time-averaging intervals, we found the best so far results to be given by the ram pressure Pd, SYM-H, and N-index by Newell et al. (2007). In addition, the IMF By has also been included as a model driver, with a goal to more accurately represent the IMF penetration effects. The model faithfully reproduces both externally and internally induced variations in the global distribution of the geomagnetic field and electric currents. Stronger solar wind driving results in a deepening of the equatorial field depression and a dramatic increase of its dawn-dusk asymmetry. The Earth's dipole tilt causes a consistent deformation of the magnetotail current sheet and a significant north-south asymmetry of the polar cusp depressions on the dayside. Next steps to further develop the new approach are also discussed.

  8. Geocenter Coordinates from a Combined Processing of LEO and Ground-based GPS Observations

    Science.gov (United States)

    Männel, Benjamin; Rothacher, Markus

    2017-04-01

    The GPS observations provided by the global IGS (International GNSS Service) tracking network play an important role for the realization of a unique terrestrial reference frame that is accurate enough to allow the monitoring of the Earth's system. Combining these ground-based data with GPS observations tracked by high-quality dual-frequency receivers on-board Low Earth Orbiters (LEO) might help to further improve the realization of the terrestrial reference frame and the estimation of the geocenter coordinates, GPS satellite orbits and Earth rotation parameters (ERP). To assess the scope of improvement, we processed a network of 50 globally distributed and stable IGS-stations together with four LEOs (GRACE-A, GRACE-B, OSTM/Jason-2 and GOCE) over a time interval of three years (2010-2012). To ensure fully consistent solutions the zero-difference phase observations of the ground stations and LEOs were processed in a common least-square adjustment, estimating GPS orbits, LEO orbits, station coordinates, ERPs, site-specific tropospheric delays, satellite and receiver clocks and ambiguities. We present the significant impact of the individual LEOs and a combination of all four LEOs on geocenter coordinates derived by using a translational approach (also called network shift approach). In addition, we present geocenter coordinates derived from the same set of GPS observations by using a unified approach. This approach combines the translational and the degree-one approach by estimating translations and surface deformations simultaneously. Based on comparisons against each other and against geocenter time series derived by other techniques the effect of the selected approach is assessed.

  9. Minimal Mirror Twin Higgs

    CERN Document Server

    Barbieri, Riccardo; Harigaya, Keisuke

    2016-01-01

    In a Mirror Twin World with a maximally symmetric Higgs sector the little hierarchy of the Standard Model can be significantly mitigated, perhaps displacing the cutoff scale above the LHC reach. We show that consistency with observations requires that the Z2 parity exchanging the Standard Model with its mirror be broken in the Yukawa couplings. A minimal such effective field theory, with this sole Z2 breaking, can generate the Z2 breaking in the Higgs sector necessary for the Twin Higgs mechanism, and has constrained and correlated signals in invisible Higgs decays, direct Dark Matter Detection and Dark Radiation, all within reach of foreseen experiments. For dark matter, both mirror neutrons and a variety of self-interacting mirror atoms are considered. Neutrino mass signals and the effects of a possible additional Z2 breaking from the vacuum expectation values of B-L breaking fields are also discussed.

  10. The Athena Mirror

    Science.gov (United States)

    Wille, Eric

    2016-07-01

    The Athena mission (Advanced Telescope for High Energy Astrophysics) requires lightweight X-ray Wolter optics with a high angular resolution and large effective area. For achieving an effective area of 2 m^2 (at 1 keV) and an angular resolution of below 5 arcsec, the Silicon Pore Optics technology was developed by ESA together with a consortium of European industry. Silicon Pore Optics are made of commercial Si wafers using process technology adapted from the semiconductor industry. We present the current design of the Athena mirror concentrating on the technology development status of the Silicon Pore Optics, ranging from the manufacturing of single mirror plates towards complete focusing mirror modules and their integration into the mirror structure.

  11. Mirror reactor surface study

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, A. L.; Damm, C. C.; Futch, A. H.; Hiskes, J. R.; Meisenheimer, R. G.; Moir, R. W.; Simonen, T. C.; Stallard, B. W.; Taylor, C. E.

    1976-09-01

    A general survey is presented of surface-related phenomena associated with the following mirror reactor elements: plasma first wall, ion sources, neutral beams, director converters, vacuum systems, and plasma diagnostics. A discussion of surface phenomena in possible abnormal reactor operation is included. Several studies which appear to merit immediate attention and which are essential to the development of mirror reactors are abstracted from the list of recommended areas for surface work. The appendix contains a discussion of the fundamentals of particle/surface interactions. The interactions surveyed are backscattering, thermal desorption, sputtering, diffusion, particle ranges in solids, and surface spectroscopic methods. A bibliography lists references in a number of categories pertinent to mirror reactors. Several complete published and unpublished reports on surface aspects of current mirror plasma experiments and reactor developments are also included.

  12. Manufacturing parabolic mirrors

    CERN Multimedia

    CERN PhotoLab

    1975-01-01

    The photo shows the construction of a vertical centrifuge mounted on an air cushion, with a precision of 1/10000 during rotation, used for the manufacture of very high=precision parabolic mirrors. (See Annual Report 1974.)

  13. The obsidian mirror The obsidian mirror

    Directory of Open Access Journals (Sweden)

    Maria do Socorro Reis Amorin

    2008-04-01

    Full Text Available The author James Norman is an American who has always lived in Mexico during the summer. He seems to love Mexican - Indian traditions and he is well acquainted with the pre-historic culture as it is shown in his book: "The Obsidian Mirror". "The Obsidian Mirror" is a mysterious story about an archeologist: Quigley that lives in a small village in Mexico-San Marcos. He is searching for antiques that belong to some tribes of pre-historic Indians in order to find out their mysteries. Quigley becomes so engaged in his work that his mind has reached a stage that is impossible to separate between Quigley the archeologist, and Quigley as an ancient Indian. The culture, the myth, the sensation of Omen - characteristics of the Indians are within himself. As a result, Quigley acts sometimes as a real Indian. The author James Norman is an American who has always lived in Mexico during the summer. He seems to love Mexican - Indian traditions and he is well acquainted with the pre-historic culture as it is shown in his book: "The Obsidian Mirror". "The Obsidian Mirror" is a mysterious story about an archeologist: Quigley that lives in a small village in Mexico-San Marcos. He is searching for antiques that belong to some tribes of pre-historic Indians in order to find out their mysteries. Quigley becomes so engaged in his work that his mind has reached a stage that is impossible to separate between Quigley the archeologist, and Quigley as an ancient Indian. The culture, the myth, the sensation of Omen - characteristics of the Indians are within himself. As a result, Quigley acts sometimes as a real Indian.

  14. Mirror contamination in space I: mirror modelling

    Science.gov (United States)

    Krijger, J. M.; Snel, R.; van Harten, G.; Rietjens, J. H. H.; Aben, I.

    2014-10-01

    We present a comprehensive model that can be employed to describe and correct for degradation of (scan) mirrors and diffusers in satellite instruments that suffer from changing optical Ultraviolet to visible (UV-VIS) properties during their operational lifetime. As trend studies become more important, so does the importance of understanding and correcting for this degradation. This is the case not only with respect to the transmission of the optical components, but also with respect to wavelength, polarisation, or scan-angle effects. Our hypothesis is that mirrors in flight suffer from the deposition of a thin absorbing layer of contaminant, which slowly builds up over time. We describe this with the Mueller matrix formalism and Fresnel equations for thin multi-layer contamination films. Special care is taken to avoid the confusion often present in earlier publications concerning the Mueller matrix calculus with out-of-plane reflections. The method can be applied to any UV-VIS satellite instrument. We illustrate and verify our approach to the optical behaviour of the multiple scan mirrors of SCIAMACHY (onboard ENVISAT).

  15. Detection of the Zeeman effect in atmospheric O2 using a ground-based microwave radiometer

    Science.gov (United States)

    Navas-Guzmán, Francisco; Kämpfer, Niklaus; Murk, Axel; Larsson, Richard; Buehler, Stefan A.; Eriksson, Patrick

    2015-04-01

    In this work we study the Zeeman effect on stratospheric O2 using ground-based microwave radiometer measurements. The Zeeman effect is a phenomenon which occurs when an external magnetic field interacts with a molecule or an atom of total electron spin different from zero. Such an interaction will split an original energy level into several sub-levels [1]. In the atmosphere, oxygen is an abundant molecule which in its ground electronic state has a permanent magnetic dipole moment coming from two parallel electron spins. The interaction of the magnetic dipole moment with the Earth magnetic field leads to a Zeeman splitting of the O2 rotational transitions which polarizes the emission spectra. A special campaign was carried out in order to measure this effect in the oxygen emission line centered at 53.07 GHz in Bern (Switzerland). The measurements were possible using a Fast Fourier Transform (FFT) spectrometer with 1 GHz of band width to measure the whole oxygen emission line centered at 53.07 GHz and a narrow spectrometer (4 MHz) to measure the center of the line with a very high resolution (1 kHz). Both a fixed and a rotating mirror were incorporated to the TEMPERA (TEMPERature RAdiometer) radiometer in order to be able to measure under different observational angles. This new configuration allowed us to change the angle between the observational path and the Earth magnetic field direction. The measured spectra showed a clear polarized signature when the observational angles were changed evidencing the Zeeman effect in the oxygen molecule. In addition, simulations carried out with the Atmospheric Radiative Transfer Simulator (ARTS) [2] allowed us to verify the microwave measurements showing a very good agreement between model and measurements. The incorporation of this effect to the forward model will allow to extend the temperature retrievals beyond 50 km. This improvement in the forward model will be very useful for the assimilation of brightness temperatures in

  16. Roughness tolerances for Cherenkov telescope mirrors

    CERN Document Server

    Tayabaly, K; Canestrari, R; Bonnoli, G; Lavagna, M; Pareschi, G

    2016-01-01

    The Cherenkov Telescope Array (CTA) is a forthcoming international ground-based observatory for very high-energy gamma rays. Its goal is to reach sensitivity five to ten times better than existing Cherenkov telescopes such as VERITAS, H.E.S.S. or MAGIC and extend the range of observation to energies down to few tens of GeV and beyond 100 TeV. To achieve this goal, an array of about 100 telescopes is required, meaning a total reflective surface of several thousands of square meters. Thence, the optimal technology used for CTA mirrors manufacture should be both low-cost (~1000 euros/m2) and allow high optical performances over the 300-550 nm wavelength range. More exactly, a reflectivity higher than 85% and a PSF (Point Spread Function) diameter smaller than 1 mrad. Surface roughness can significantly contribute to PSF broadening and limit telescope performances. Fortunately, manufacturing techniques for mirrors are now available to keep the optical scattering well below the geometrically-predictable effect of ...

  17. Study on supporting force sensing and control during large aperture space mirror test

    Science.gov (United States)

    Zhang, Long; Hu, Wenqi; Zheng, Liehua; Hao, Peiming

    2016-10-01

    During the machining of large aperture lightweight space mirror, the mirror figure consistency between ground test and space mission is a problem. In order to effectively control the supporting deformation effect on test results in gravity environment, in view of a 1.2-m space mirror with back blind holes, a supporting method for optical axis horizontal test is proposed, with this method, mirror under test is positioned by three center hole surfaces and supported by six external hole surfaces. The effect of deformation caused by different supporting force value, area and position is analyzed by finite element method, the simulation results show that this supporting method can control the mirror supporting deformation within PV0.035λ rms0.005λ. The actual supporting system uses soft expansion mandrel to control the mirror position and pneumatic lever to realize the floating support. In order to ensure that the support force can evenly distribute on the contact surface, a pressure mapping system is adopted to measure the interface pressure between the mirror blind holes and the soft supporting pads for the first time. This method can meet the test requirements of rms=1/40λ mirror and provides a technical support for high precision test of large aperture space mirror with back blind holes.

  18. Mirror decay of {sup 75}Sr

    Energy Technology Data Exchange (ETDEWEB)

    Huikari, J.; Huang, W.X. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40351, Jyvaeskylae (Finland); Oinonen, M. [Helsinki Institute of Physics, FIN-00014 University of Helsinki (Finland); CERN, CH-1211 Geneva 23 (Switzerland); Algora, A.; Nacher, E. [Instituto de Fisica Corpuscular, CSIC - University of Valencia, E-46071 Valencia (Spain); Cederkaell, J.; Fraile, L.; Franchoo, S.; Fynbo, H.; Peraejaervi, K.; Weissman, L. [CERN, CH-1211 Geneva 23 (Switzerland); Courtin, S.; Dessagne, P.; Knipper, A.; Marechal, F.; Miehe, C.; Poirier, E. [Institut de Recherches Subatomiques, F-67037 Strasbourg Cedex 2 (France); Jokinen, A.; Aeystoe, J. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40351, Jyvaeskylae (Finland); Helsinki Institute of Physics, FIN-00014 University of Helsinki (Finland)

    2003-03-01

    The {beta}-decay of {sup 75}Sr to its mirror nucleus {sup 75}Rb was studied at the ISOLDE PSB facility at CERN by means of {beta}-delayed {gamma} and proton spectroscopy. The decay Q-value and {beta}-delayed {gamma} intensity were measured for the first time. These results, 10.60{+-}0.22 MeV and 4.5{sup +1.9}{sub -0.7}%, together with accurate measurements of the {beta}-decay half-life and {beta}-delayed proton branching ratio yielded the Gamow-Teller strength 0.35{+-}0.05 for the mirror transition. Implications of the results on studies of deformation effects and on the path of the rapid proton capture process are discussed. (orig.)

  19. Decrypting geophysical signals at Stromboli Volcano (Italy): Integration of seismic and Ground-Based InSAR displacement data.

    Science.gov (United States)

    Di Traglia, F; Cauchie, L; Casagli, N; Saccorotti, G

    2014-04-28

    We present the integration of seismic and Ground-Based Interferometric Synthetic Aperture Radar system (GBInSAR) displacement data at Stromboli Volcano. Ground deformation in the area of summit vents is positively correlated with both seismic tremor amplitude and cumulative amplitudes of very long period (VLP) signals associated with Strombolian explosions. Changes in VLP amplitudes precede by a few days the variations in ground deformation and seismic tremor. We propose a model where the arrival of fresh, gas-rich magma from depth enhances gas slug formation, promoting convection and gas transfer throughout the conduit system. At the shallowest portion of the conduit, an increase in volatile content causes a density decrease, expansion of the magmatic column and augmented degassing activity, which respectively induce inflation of the conduit, and increased tremor amplitudes. The temporal delay between increase of VLP and tremor amplitudes/conduit inflation can be interpreted in terms of the different timescales characterizing bulk gas transfer versus slug formation and ascent.

  20. Ground-based Infrared Observations of Water Vapor and Hydrogen Peroxide in the Atmosphere of Mars

    Science.gov (United States)

    Encrenaz, T.; Greathouse, T. K.; Bitner, M.; Kruger, A.; Richter, M. J.; Lacy, J. H.; Bézard, B.; Fouchet, T.; Lefevre, F.; Forget, F.; Atreya, S. K.

    2008-11-01

    Ground-based observations of water vapor and hydrogen peroxide have been obtained in the thermal infrared range, using the TEXES instrument at the NASA Infrared Telescope Facility, for different times of the seasonal cycle.

  1. Informing hydrological models with ground-based time-lapse relative gravimetry: potential and limitations

    DEFF Research Database (Denmark)

    Bauer-Gottwein, Peter; Christiansen, Lars; Rosbjerg, Dan

    2011-01-01

    Coupled hydrogeophysical inversion emerges as an attractive option to improve the calibration and predictive capability of hydrological models. Recently, ground-based time-lapse relative gravity (TLRG) measurements have attracted increasing interest because there is a direct relationship between ...

  2. Changes in ground-based solar ultraviolet radiation during fire episodes: a case study

    CSIR Research Space (South Africa)

    Wright, CY

    2013-09-01

    Full Text Available about the relationship between fires and solar UVR without local high-quality column or ground-based ambient air pollution (particulate matter in particular) data; however, the threat to public health from fires was acknowledged....

  3. Structural-optical integrated analysis on the large aperture mirror with active mounting

    Science.gov (United States)

    Ren, Zhiyuan; Zhu, Jianqiang; Liu, Zhigang

    2016-11-01

    Deformation of the large aperture mirror caused by the external environment load seriously affects the optical performance of the optical system, and there is a limit to develop the shape quality of large aperture mirror with traditional mounting method. It is effective way to reduce the optical mirror distortion with active support method, and the structural-optical integrated method is the effective means to assess the merits of the mounting for large aperture mirror. Firstly, we proposes a new support scheme that uses specific boundary constraints on the large lens edges and imposes flexible torque to resist deformation induced by gravity to improve surface quantity of large aperture mirror. We calculate distortion of the large aperture mirror at the edges of the flexible torque respectively with the finite element method; secondly, we extract distortion value within clear aperture of the mirror with MATLAB, solve the corresponding Zernike polynomial coefficients; lastly, we obtain the peak-valley value (PV) and root mean square value (RMS) with optical-structural integrated analysis . The results for the 690x400x100mm mirror show that PV and RMS values within the clear aperture with 0.4MPa torques than the case without applying a flexible torque reduces 82.7% and 72.9% respectively. The active mounting on the edge of the large aperture mirror can greatly improve the surface quality of the large aperture mirror.

  4. System Identification and Automatic Mass Balancing of Ground-Based Three-Axis Spacecraft Simulator

    Science.gov (United States)

    2006-08-01

    System Identification and Automatic Mass Balancing of Ground-Based Three-Axis Spacecraft Simulator Jae-Jun Kim∗ and Brij N. Agrawal † Department of...TITLE AND SUBTITLE System Identification and Automatic Mass Balancing of Ground-Based Three-Axis Spacecraft Simulator 5a. CONTRACT NUMBER 5b...and Dynamics, Vol. 20, No. 4, July-August 1997, pp. 625-632. 6Schwartz, J. L. and Hall, C. D., “ System Identification of a Spherical Air-Bearing

  5. White Light Focusing Mirror

    Science.gov (United States)

    Johnson, Eric; Lyndaker, Aaron; Deyhim, Alex; Sullivan, Michael; Chance, Mark; Abel, Don; Toomey, John; Hulbert, Steven

    2007-01-01

    The NSLS X28C white-light beamline is being outfitted with a focusing mirror in order to increase, as well as control, the x-ray intensity at the sample position. The new mirror is a 50 mm × 100 mm × 1100 mm single crystal silicon cylindrical 43.1mm radius substrate bendable to a toroid from infinite to 1200 m radius. The unique feature of this mirror system is the dual use of Indalloy 51 as both a mechanism for heat transfer and a buoyant support to negate the effects of gravity. The benefit of the liquid metal support is the ability to correct for minor slope errors that take the form of a parabola. A bobber mechanism is employed to displace the fluid under the mirror +/- 1.5 mm. This allows RMS slope error correction on the order of 2 urad. The unique mounting of the mirror ensures the contributions to slope error from errant mechanical stresses due to machining tolerances are virtually non-existent. After correction, the surface figure error (measured minus ideal) is <= 0.5 urad rms.

  6. Influence functions of a thin shallow meniscus-shaped mirror.

    Science.gov (United States)

    Arnold, L

    1997-04-01

    Thin shallow spherical shell theory is used to derive the general influence function, owing to uniform and/or discrete (actuators) loads, for a thin shallow meniscus-shaped mirror of uniform thickness with a central hole and supported at discrete points. Small elastic deformations are considered. No symmetry on the load distribution constrains the model. Explicit analytical expressions of the set of equations are given for calculating the influence functions. Results agree with the finite element analysis (FEA) to within 1%. When the FEA requires megabytes of RAM memory, the analytical method needs only kilobytes and typically runs 30 times faster. This is a crucial advantage for the iterative optimization of mirror supports such as large passive or active meniscus-shaped primary mirror supports or Cassegrain/Gregorian adaptive secondary actuator configurations. References are given on estimating the shear effects (thick mirror), the thickness variation effect, and the influence of the size of the support pads.

  7. The DKIST Data Center: Meeting the Data Challenges for Next-Generation, Ground-Based Solar Physics

    Science.gov (United States)

    Davey, A. R.; Reardon, K.; Berukoff, S. J.; Hays, T.; Spiess, D.; Watson, F. T.; Wiant, S.

    2016-12-01

    The Daniel K. Inouye Solar Telescope (DKIST) is under construction on the summit of Haleakalā in Maui, and scheduled to start science operations in 2020. The DKIST design includes a four-meter primary mirror coupled to an adaptive optics system, and a flexible instrumentation suite capable of delivering high-resolution optical and infrared observations of the solar chromosphere, photosphere, and corona. Through investigator-driven science proposals, the facility will generate an average of 8 TB of data daily, comprised of millions of images and hundreds of millions of metadata elements. The DKIST Data Center is responsible for the long-term curation and calibration of data received from the DKIST, and for distributing it to the user community for scientific use. Two key elements necessary to meet the inherent big data challenge are the development of flexible public/private cloud computing and coupled relational and non-relational data storage mechanisms. We discuss how this infrastructure is being designed to meet the significant expectation of automatic and manual calibration of ground-based solar physics data, and the maximization the data's utility through efficient, long-term data management practices implemented with prudent process definition and technology exploitation.

  8. ULE design considerations for a 3m class light weighted mirror blank for E-ELT M5

    Science.gov (United States)

    Fox, Andrew; Hobbs, Tom; Edwards, Mary; Arnold, Matthew; Sawyer, Kent

    2016-07-01

    It is expected that the next generation of large ground based astronomical telescopes will need large fast-steering/tip-tilt mirrors made of ultra-lightweight construction. These fast-steering mirrors are used to continuously correct for atmospheric disturbances and telescope vibrations. An example of this is the European Extremely Large Telescope (E-ELT) M5 lightweight mirror, which is part of the Tip-Tilt/Field-Stabilization Unit. The baseline design for the E-ELT M5 mirror, as presented in the E-ELT Construction Proposal, is a closed-back ULE mirror with a lightweight core using square core cells. Corning Incorporated (Corning) has a long history of manufacturing lightweight mirror blanks using ULE in a closed-back construction, going back to the 1960's, and includes the Hubble Space Telescope primary mirror, Subaru Telescope secondary and tertiary mirrors, the Magellan I and II tertiary mirrors, and Kepler Space Telescope primary mirror, among many others. A parametric study of 1-meter class lightweight mirror designs showed that Corning's capability to seal a continuous back sheet to a light-weighted core structure provides superior mirror rigidity, in a near-zero thermal expansion material, relative to other existing technologies in this design space. Corning has investigated the parametric performance of several design characteristics for a 3-meter class lightweight mirror blank for the E-ELT M5. Finite Element Analysis was performed on several design scenarios to obtain weight, areal density, and first Eigen frequency. This paper presents an overview of Corning ULE and lightweight mirror manufacturing capabilities, the parametric performance of design characteristics for 1-meter class and 3-meter class lightweight mirrors, as well as the manufacturing advantages and disadvantages of those characteristics.

  9. Evaluation of Spaceborne SiC Mirror Materials Using Samples Cut from the Periphery of a Mirror Body

    Science.gov (United States)

    Kotani, Masaki; Muta, Yoshikazu; Yoshimura, Akinori; Ogihara, Shinji; Imai, Tadashi; Katayama, Haruyoshi; Yui, Yukari; Tange, Yoshio; Enya, Keigo; Kaneda, Hidehiro; Nakagawa, Takao

    2014-03-01

    The Japan Aerospace Exploration Agency has studied large-scale, lightweight mirrors constructed of SiC-based materials as a key technology for future earth observations and astronomical missions. One of the most important technical issues for large-scale ceramic components is their quality stability (viz., differences in material properties depending on the part and the processing), which might influence the structural and/or thermal reliability through unforeseen deformation and breakage. In this study, the authors used a simple, low-cost method for evaluating the properties of SiC mirror materials. Using mechanical testing, thermodilatometry, and microstructural analysis on samples cut from the periphery of a prototype 800-mm-diameter mirror body, the overall quality of the mirror body material was determined.

  10. Orbifolded Konishi from the mirror TBA

    Energy Technology Data Exchange (ETDEWEB)

    De Leeuw, Marius [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institute, Am Muehlenberg 1, 14476 Potsdam (Germany); Van Tongeren, Stijn J, E-mail: Marius.de.Leeuw@aei.mpg.de, E-mail: S.J.vanTongeren@uu.nl [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, 3508 TD Utrecht (Netherlands)

    2011-08-12

    Starting with a discussion of the general applicability of the simplified mirror thermodynamic Bethe ansatz (TBA) equations to simple deformations of the AdS{sub 5} x S{sup 5} superstring, we proceed to study a specific type of orbifold to which the undeformed simplified TBA equations directly apply. We then use this set of equations, as well as Luescher's approach, to determine the next-to-leading-order wrapping correction to the energy of what we call the orbifolded Konishi state and show that they perfectly agree. In addition we discuss wrapping corrections to the ground-state energy of the orbifolded model under consideration.

  11. Surface micromachined scanning mirrors

    DEFF Research Database (Denmark)

    Mattsson, Kent Erik

    1992-01-01

    Both aluminum cantilever and torsional scanning mirrors have been fabricated and their static and dynamic properties are studied experimentally and theoretically. The experiments showed resonance frequencies in the range of 163 k-Hz - 632 kHz for cantilever beams with Q values between 5 and 11....... Torsional mirrors showed resonance frequencies in the range of 410 kHz - 667 kHz with Q values of 10 - 17. All measurements performed at atmospheric pressure. Both types of mechanical structures were deflected electrostatically at large angles (± 5°) more than 1011 times without breaking and without any...

  12. Unification with mirror fermions

    Directory of Open Access Journals (Sweden)

    Triantaphyllou George

    2014-04-01

    Full Text Available We present a new framework unifying interactions in nature by introducing mirror fermions, explaining the hierarchy between the weak scale and the coupling unification scale, which is found to lie close to Planck energies. A novel process leading to the emergence of symmetry is proposed, which not only reduces the arbitrariness of the scenario proposed but is also followed by significant cosmological implications. Phenomenology includes the probability of detection of mirror fermions via the corresponding composite bosonic states and the relevant quantum corrections at the LHC.

  13. Mirror neurons and mirror systems in monkeys and humans.

    Science.gov (United States)

    Fabbri-Destro, Maddalena; Rizzolatti, Giacomo

    2008-06-01

    Mirror neurons are a distinct class of neurons that transform specific sensory information into a motor format. Mirror neurons have been originally discovered in the premotor and parietal cortex of the monkey. Subsequent neurophysiological (TMS, EEG, MEG) and brain imaging studies have shown that a mirror mechanism is also present in humans. According to its anatomical locations, mirror mechanism plays a role in action and intention understanding, imitation, speech, and emotion feeling.

  14. Some Considerations for Precision Metrology of Thin X-Ray Mirrors

    Science.gov (United States)

    Lehan, J. P.; Saha, T.; Zhang, W. W.; Rohrbach, S.; Chan, K.-W.; Hadjimichael, T.; Hong, M.; Davis, W.

    2008-01-01

    Determination of the shape of very thin x-ray mirrors employed in spaced-based telescopes continues to be challenging. The mirrors shapes are not readily deduced to the required accuracy because the mount induced distortions are often larger than the uncertainty tolerable for the mission metrology. In addition to static deformations, dynamic and thermal considerations are exacerbated for this class of mirrors. We report on the performance of one temporary mounting scheme for the thin glass mirrors for the Constellation-X mission and prospects for deducing their undistorted shapes.

  15. Wavefront alignment research of segmented mirror synthetic aperture optical (SAO) system

    Science.gov (United States)

    Deng, Jian; An, Xiaoqiang; Tian, Hao

    2010-05-01

    Wavefront control technology and imaging experiment are introduced for a segmented mirror SAO system with deformable sub-mirrors. This system is a RC style with 300mm aperture, 4.5 F#, +/-0.4°FOV, 0.45~0.75μm wave band, and diffraction-limit design MTF. The primary mirror is composed by three sub-mirrors, with parabolic shape, and each deformable sub-mirror has 19 actuators to control and keep the surface shape, and 5 actuators to align sub-mirrors location in 5 degree of freedom. Interferometer is used to feed back and control exit wavefront error, and base on measurement and finite element analysis, location and quanitity of actuators are optimized, making the surface shape and misadjustment errors interact and compensate each other, and the synthetic system exit pupil wavefront error is controlled. The integrated exit pupil wavefront errors are gotten by ZYGO interferometer, and central FOV is 0.077λRMS, and edge FOV is 0.093λRMS. At the end, an imaging experiment is executed, and good results are obtained, which proves, the deformable sub-mirrors have the ability to meliorate alignment and the latter can retroact the former, and this relationship iterate make system exit pupil wavefront error convergence and improve segmented mirror SAO system imaging ability.

  16. Effects of thermal inhomogeneity on 4m class mirror substrates

    Science.gov (United States)

    Jedamzik, Ralf; Kunisch, Clemens; Westerhoff, Thomas

    2016-07-01

    The new ground based telescope generation is moving to a next stage of performance and resolution. Mirror substrate material properties tolerance and homogeneity are getting into focus. The coefficient of thermal expansion (CTE) homogeneity is even more important than the absolute CTE. The error in shape of a mirror, even one of ZERODUR, is affected by changes in temperature, and by gradients in temperature. Front to back gradients will change the radius of curvature R that in turn will change the focus. Some systems rely on passive athermalization and do not have means to focus. Similarly changes in soak temperature will result in surface changes to the extent there is a non-zero coefficient of thermal expansion. When there are in-homogeneities in CTE, the mirror will react accordingly. Results of numerical experiments are presented discussing the impact of CTE in-homogeneities on the optical performance of 4 m class mirror substrates. Latest improvements in 4 m class ZERODUR CTE homogeneity and the thermal expansion metrology are presented as well.

  17. Rearview Mirror Dimming Function

    Science.gov (United States)

    Layton, William

    2011-01-01

    Students are often unaware of the little tab on a rear-view mirror that is used to dim headlights from the rear. Those who know about this tab are usually interested in knowing how it works. Explanations of the optics involved can be found in Serway and Jewett and Jones and Edge. An alternate explanation is given.

  18. Rearview Mirror Dimming Function

    Science.gov (United States)

    Layton, William

    2011-01-01

    Students are often unaware of the little tab on a rear-view mirror that is used to dim headlights from the rear. Those who know about this tab are usually interested in knowing how it works. Explanations of the optics involved can be found in Serway and Jewett and Jones and Edge. An alternate explanation is given.

  19. GB-SAR Experiment On Deformation Extraction And System Error Analysis

    Science.gov (United States)

    Qu, Shibo; Wang, Yanping; Tan, Weixian; Hong, Wen

    2010-10-01

    Ground Based Synthetic Aperture Radar (GB-SAR) provides a new method to monitoring deformation in relative small region. In this paper, we present the GB-SAR imaging geometry and analyze the interferometric phase for the purpose of deformation monitoring. Deformation monitoring error sources are also analyzed through sensitivity equations, including frequency instability and its influence on interferometric phase and deformation extraction, incident angle and monitoring distance. At last, a deformation monitoring experiment is carry out using ASTRO (Advanced Scannable Two-dimensional Rail Observation system), a GB-SAR system constructed by Institute of Electronics Chinese Academy of Sciences (IECAS). The deformation monitoring results show good consistent with metal objects' movement.

  20. On deformations of triangulated models

    CERN Document Server

    De Deken, Olivier

    2012-01-01

    This paper is the first part of a project aimed at understanding deformations of triangulated categories, and more precisely their dg and A infinity models, and applying the resulting theory to the models occurring in the Homological Mirror Symmetry setup. In this first paper, we focus on models of derived and related categories, based upon the classical construction of twisted objects over a dg or $A_{\\infty}$-algebra. For a Hochschild 2 cocycle on such a model, we describe a corresponding "curvature compensating" deformation which can be entirely understood within the framework of twisted objects. We unravel the construction in the specific cases of derived A infinity and abelian categories, homotopy categories, and categories of graded free qdg-modules. We identify a purity condition on our models which ensures that the structure of the model is preserved under deformation. This condition is typically fulfilled for homotopy categories, but not for unbounded derived categories.

  1. Derived Categories of BHK Mirrors

    CERN Document Server

    Favero, David

    2016-01-01

    We prove a derived analogue to the results of Borisov, Clarke, Kelly, and Shoemaker on the birationality of Berglund-Hubsch-Krawitz mirrors. Heavily bootstrapping off work of Seidel and Sheridan, we obtain Homological Mirror Symmetry for Berglund-Hubsch-Krawitz mirror pencils to hypersurfaces in projective space.

  2. 地基大口径望远镜系统结构技术综述%Overview of structure technologies of large aperture ground-based telescopes

    Institute of Scientific and Technical Information of China (English)

    张景旭

    2012-01-01

    The developing status of large aperture ground-based telescopes is reviewed in this paper.The significance of bigger apertures for telescopes and their main technological approaches are expatiated and the summary on appliance values of modern large aperture telescopes is given.Then,it introduces five kinds of modern typical large telescope systems,which represent the topmost technological level.The key structures and technologies of large telescopes about mount,telescope tubes,primary mirror supports and secondary mirror assemblies are disscussed.Finally,it summarizes the developing trends of the large aperture ground-based telescopes and points out that some of the optical systems in the telescopes have been changed from coaxial systems to off-axial systems,while they are better application prospects.%概述了地基大口径望远镜的发展状况,阐述了口径变大的意义及实现的关键技术途径。概括了当前大口径望远镜的应用价值。介绍了国外5种典型的大口径望远镜系统,它们代表了当前地基大口径望远镜发展的最高技术水平。从跟踪架、主望远镜筒、主镜支撑及次镜支撑调整几个方面论述了大口径望远镜的结构特点及关键技术。最后,总结了大口径望远镜系统的发展趋势,指出其光学系统已从同轴系统向离轴系统发展并极具应用前景。

  3. Ground-based follow-up in relation to Kepler Asteroseismic Investigation

    CERN Document Server

    Uytterhoeven, K; Bruntt, H; De Cat, P; Frandsen, S; Gutierrez-Soto, J; Kiss, L; Kurtz, D W; Marconi, M; Molenda-Zakowicz, J; Ostensen, R; Randall, S; Southworth, J; Szabo, R

    2010-01-01

    The Kepler space mission, successfully launched in March 2009, is providing continuous, high-precision photometry of thousands of stars simultaneously. The uninterrupted time-series of stars of all known pulsation types are a precious source for asteroseismic studies. The Kepler data do not provide information on the physical parameters, such as effective temperature, surface gravity, metallicity, and vsini, which are crucial for successful asteroseismic modelling. Additional ground-based time-series data are needed to characterize mode parameters in several types of pulsating stars. Therefore, ground-based multi-colour photometry and mid/high-resolution spectroscopy are needed to complement the space data. We present ground-based activities within KASC on selected asteroseismic Kepler targets of several pulsation types. (Based on observations made with the Isaac Newton Telescope, William Herschel Telescope, Nordic Optical Telescope, Telescopio Nazionale Galileo, Mercator Telescope (La Palma, Spain), and IAC-...

  4. BigBOSS: The Ground-Based Stage IV BAO Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Schlegel, David; Bebek, Chris; Heetderks, Henry; Ho, Shirley; Lampton, Michael; Levi, Michael; Mostek, Nick; Padmanabhan, Nikhil; Perlmutter, Saul; Roe, Natalie; Sholl, Michael; Smoot, George; White, Martin; Dey, Arjun; Abraham, Tony; Jannuzi, Buell; Joyce, Dick; Liang, Ming; Merrill, Mike; Olsen, Knut; Salim, Samir

    2009-04-01

    The BigBOSS experiment is a proposed DOE-NSF Stage IV ground-based dark energy experiment to study baryon acoustic oscillations (BAO) and the growth of structure with an all-sky galaxy redshift survey. The project is designed to unlock the mystery of dark energy using existing ground-based facilities operated by NOAO. A new 4000-fiber R=5000 spectrograph covering a 3-degree diameter field will measure BAO and redshift space distortions in the distribution of galaxies and hydrogen gas spanning redshifts from 0.2< z< 3.5. The Dark Energy Task Force figure of merit (DETF FoM) for this experiment is expected to be equal to that of a JDEM mission for BAO with the lower risk and cost typical of a ground-based experiment.

  5. Comparing Dawn, Hubble Space Telescope, and Ground-Based Interpretations of (4) Vesta

    CERN Document Server

    Reddy, Vishnu; Corre, Lucille Le; Scully, Jennifer E C; Gaskell, Robert; Russell, Christopher T; Park, Ryan S; Nathues, Andreas; Raymond, Carol; Gaffey, Michael J; Sierks, Holger; Becker, Kris J; McFadden, Lucy A

    2013-01-01

    Observations of asteroid 4 Vesta by NASA's Dawn spacecraft are interesting because its surface has the largest range of albedo, color and composition of any other asteroid visited by spacecraft to date. These hemispherical and rotational variations in surface brightness and composition have been attributed to impact processes since Vesta's formation. Prior to Dawn's arrival at Vesta, its surface properties were the focus of intense telescopic investigations for nearly a hundred years. Ground-based photometric and spectroscopic observations first revealed these variations followed later by those using Hubble Space Telescope. Here we compare interpretations of Vesta's rotation period, pole, albedo, topographic, color, and compositional properties from ground-based telescopes and HST with those from Dawn. Rotational spectral variations observed from ground-based studies are also consistent with those observed by Dawn. While the interpretation of some of these features was tenuous from past data, the interpretati...

  6. Ka-band bistatic ground-based SAR using noise signals

    Science.gov (United States)

    Lukin, K.; Mogyla, A.; Vyplavin, P.; Palamarchuk, V.; Zemlyaniy, O.; Tarasenko, V.; Zaets, N.; Skretsanov, V.; Shubniy, A.; Glamazdin, V.; Natarov, M.; Nechayev, O.

    2008-01-01

    Currently, one of the actual problems is remote monitoring of technical state of large objects. Different methods can be used for that purpose. The most promising of them relies on application of ground based synthetic aperture radars (SAR) and differential interferometry. We have designed and tested Ground Based Noise Waveform SAR based on noise radar technology [1] and synthetic aperture antennas [2]. It enabled to build an instrument for precise all-weather monitoring of large objects in real-time. We describe main performance of ground-based interferometric SAR which uses continuous Ka-band noise waveform as a probe signal. Besides, results of laboratory trials and evaluation of its main performance are presented as well.

  7. Mechanical and Thermal Tests of the Containers of Liquid Mirrors

    CERN Document Server

    Borra, E F; Tremblay, G; Daigle, A; Huot, Y

    2003-01-01

    We give a generic description of a liquid mirror system and summarize some practical information useful to making them. We compare laboratory measurements of deformations, due to the weight of mercury on the container of a 3.7-m mirror and to temperature changes on a 1-m container, to finite element computer simulations. We find that the measurements agree reasonably well with the numerical simulations. The measurements on the 1-m container show no evidence of fatigue after a few thermal cycles. These results validate the computer models of containers described in a companion article.

  8. Mirror image agnosia.

    Science.gov (United States)

    Chandra, Sadanandavalli Retnaswami; Issac, Thomas Gregor

    2014-10-01

    Gnosis is a modality-specific ability to access semantic knowledge of an object or stimulus in the presence of normal perception. Failure of this is agnosia or disorder of recognition. It can be highly selective within a mode. self-images are different from others as none has seen one's own image except in reflection. Failure to recognize this image can be labeled as mirror image agnosia or Prosopagnosia for reflected self-image. Whereas mirror agnosia is a well-recognized situation where the person while looking at reflected images of other objects in the mirror he imagines that the objects are in fact inside the mirror and not outside. Five patients, four females, and one male presented with failure to recognize reflected self-image, resulting in patients conversing with the image as a friend, fighting because the person in mirror is wearing her nose stud, suspecting the reflected self-image to be an intruder; but did not have prosopagnosia for others faces, non living objects on self and also apraxias except dressing apraxia in one patient. This phenomena is new to our knowledge. Mirror image agnosia is an unique phenomena which is seen in patients with parietal lobe atrophy without specificity to a category of dementing illness and seems to disappear as disease advances. Reflected self-images probably have a specific neural substrate that gets affected very early in posterior dementias specially the ones which predominantly affect the right side. At that phase most patients are mistaken as suffering from psychiatric disorder as cognition is moderately preserved. As disease becomes more widespread this symptom becomes masked. A high degree of suspicion and proper assessment might help physicians to recognize the organic cause of the symptom so that early therapeutic interventions can be initiated. Further assessment of the symptom with FMRI and PET scan is likely to solve the mystery of how brain handles reflected self-images. A new observation involving failure

  9. Mirror image agnosia

    Directory of Open Access Journals (Sweden)

    Sadanandavalli Retnaswami Chandra

    2014-01-01

    Full Text Available Background: Gnosis is a modality-specific ability to access semantic knowledge of an object or stimulus in the presence of normal perception. Failure of this is agnosia or disorder of recognition. It can be highly selective within a mode. self-images are different from others as none has seen one′s own image except in reflection. Failure to recognize this image can be labeled as mirror image agnosia or Prosopagnosia for reflected self-image. Whereas mirror agnosia is a well-recognized situation where the person while looking at reflected images of other objects in the mirror he imagines that the objects are in fact inside the mirror and not outside. Material and Methods:: Five patients, four females, and one male presented with failure to recognize reflected self-image, resulting in patients conversing with the image as a friend, fighting because the person in mirror is wearing her nose stud, suspecting the reflected self-image to be an intruder; but did not have prosopagnosia for others faces, non living objects on self and also apraxias except dressing apraxia in one patient. This phenomena is new to our knowledge. Results: Mirror image agnosia is an unique phenomena which is seen in patients with parietal lobe atrophy without specificity to a category of dementing illness and seems to disappear as disease advances. Discussion: Reflected self-images probably have a specific neural substrate that gets affected very early in posterior dementias specially the ones which predominantly affect the right side. At that phase most patients are mistaken as suffering from psychiatric disorder as cognition is moderately preserved. As disease becomes more widespread this symptom becomes masked. A high degree of suspicion and proper assessment might help physicians to recognize the organic cause of the symptom so that early therapeutic interventions can be initiated. Further assessment of the symptom with FMRI and PET scan is likely to solve the mystery

  10. Deformation twinning in monazite

    Energy Technology Data Exchange (ETDEWEB)

    Hay, R.S.; Marshall, D.B

    2003-10-20

    Polycrystalline monazite (LaPO{sub 4}) was deformed at room temperature by a spherical indenter. Deformation twins were identified by TEM in 70 grains. Five twin planes were found: (100) was by far the most common; (001) and (120) were less common; (122-bar)was rare, and kinks in (120) twins were identified as irrational '(483)' twin planes. The twinning modes on these planes were inferred from the expression of twinning shear at free surfaces, predictions of classical deformation twinning theory, and various considerations of twin morphology and crystal structure. Atomic shuffle calculations that allow formation of either a glide plane or a mirror plane at the twin interface were used to analyze twin modes. The inferred twin modes all have small atomic shuffles. For (001) twins, the smallest shuffles were obtained with a glide plane at the interface, with displacement vector R=((1)/(2))[010]. The results do not uniquely define a twin mode on (100), leaving open the possibility of more than one mode operating on this plane. Factors that may determine the operative deformation twinning modes are discussed. Crystal structure considerations suggest that the relative abundance of twinning modes may correlate with low shear modulus on the twin plane in the direction of twinning shear, and with a possible low-energy interface structure consisting of a layer of xenotime of one half-unit-cell thickness that could form at (100) and (001) twins. The three most common twins have low strains to low {sigma} coincidence site lattices (CSLs)

  11. First ground-based FTIR-observations of methane in the tropics

    Directory of Open Access Journals (Sweden)

    A. K. Petersen

    2010-02-01

    Full Text Available Total column concentrations and volume mixing ratio profiles of methane have been retrieved from ground-based solar absorption FTIR spectra in the near-infrared recorded in Paramaribo (Suriname. The methane FTIR observations are compared with TM5 model simulations and satellite observations from SCIAMACHY, and represent the first validation of SCIAMACHY retrievals in the tropics using ground-based remote sensing techniques. Apart from local biomass burning features, our methane FTIR observations agree well with the SCIAMACHY retrievals and TM5 model simulations.

  12. Extended lateral heating of the nighttime ionosphere by ground-based VLF transmitters

    OpenAIRE

    İnan, Umran Savaş; Graf, K. L.; Spasojevic, M.; Marshall, R. A.; Lehtinen, N. G.; Foust, F. R.

    2013-01-01

    JOURNAL OF GEOPHYSICAL RESEARCH: SPACE PHYSICS, VOL. 118, 7783–7797, doi:10.1002/2013JA019337, 2013 Extended lateral heating of the nighttime ionosphere by ground-based VLF transmitters K. L. Graf,1 M. Spasojevic,1 R. A. Marshall,2 N. G. Lehtinen,1 F. R. Foust,1 and U. S. Inan1,3 Received 16 August 2013; revised 9 October 2013; accepted 11 November 2013; published 3 December 2013. [1] The effects of ground-based very low frequency (VLF) transmitters on the lower ionospher...

  13. Status of advanced ground-based laser interferometers for gravitational-wave detection

    CERN Document Server

    Dooley, Katherine L; Dwyer, Sheila; Puppo, Paola

    2014-01-01

    Ground-based laser interferometers for gravitational-wave (GW) detection were first constructed starting 20 years ago and as of 2010 collection of several years' worth of science data at initial design sensitivities was completed. Upgrades to the initial detectors together with construction of brand new detectors are ongoing and feature advanced technologies to improve the sensitivity to GWs. This conference proceeding provides an overview of the common design features of ground-based laser interferometric GW detectors and establishes the context for the status updates of each of the four gravitational-wave detectors around the world: Advanced LIGO, Advanced Virgo, GEO600 and KAGRA.

  14. Asteroseismology of solar-type stars with Kepler: III. Ground-based data

    DEFF Research Database (Denmark)

    Karoff, Christoffer; Molenda-Żakowicz , J.

    2010-01-01

    We report on the ground-based follow-up program of spectroscopic and photometric observations of solar-like asteroseismic targets for the Kepler space mission. These stars constitute a large group of more than a thousand objects which are the subject of an intensive study by the Kepler Asteroseis......We report on the ground-based follow-up program of spectroscopic and photometric observations of solar-like asteroseismic targets for the Kepler space mission. These stars constitute a large group of more than a thousand objects which are the subject of an intensive study by the Kepler...

  15. Estimation of solar irradiance using ground-based whole sky imagers

    CERN Document Server

    Dev, Soumyabrata; Lee, Yee Hui; Winkler, Stefan

    2016-01-01

    Ground-based whole sky imagers (WSIs) can provide localized images of the sky of high temporal and spatial resolution, which permits fine-grained cloud observation. In this paper, we show how images taken by WSIs can be used to estimate solar radiation. Sky cameras are useful here because they provide additional information about cloud movement and coverage, which are otherwise not available from weather station data. Our setup includes ground-based weather stations at the same location as the imagers. We use their measurements to validate our methods.

  16. Bosonization and Mirror Symmetry

    CERN Document Server

    Kachru, Shamit; Torroba, Gonzalo; Wang, Huajia

    2016-01-01

    We study bosonization in 2+1 dimensions using mirror symmetry, a duality that relates pairs of supersymmetric theories. Upon breaking supersymmetry in a controlled way, we dynamically obtain the bosonization duality that equates the theory of a free Dirac fermion to QED3 with a single scalar boson. This duality may be used to demonstrate the bosonization duality relating an $O(2)$-symmetric Wilson-Fisher fixed point to QED3 with a single Dirac fermion, Peskin-Dasgupta-Halperin duality, and the recently conjectured duality relating the theory of a free Dirac fermion to fermionic QED3 with a single flavor. Chern-Simons and BF couplings for both dynamical and background gauge fields play a central role in our approach. In the course of our study, we describe a chiral mirror pair that may be viewed as the minimal supersymmetric generalization of the two bosonization dualities.

  17. Dynamic coherent backscattering mirror

    Energy Technology Data Exchange (ETDEWEB)

    Zeylikovich, I.; Xu, M., E-mail: mxu@fairfield.edu [Physics Department, Fairfield University, Fairfield, CT 06824 (United States)

    2016-02-15

    The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation.

  18. Dynamic coherent backscattering mirror

    Science.gov (United States)

    Xu, M.

    2016-01-01

    The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation. PMID:26937296

  19. Mirror Principle, 1

    CERN Document Server

    Lian Bong H; Yau, S T

    1997-01-01

    We propose and study the following Mirror Principle: certain sequences of multiplicative equivariant characteristic classes on Kontsevich's stable map moduli spaces can be computed in terms of certain hypergeometric type classes. As applications, we compute the equivariant Euler classes of obstruction bundles induced by any concavex bundles -- including any direct sum of line bundles -- on $\\P^n$. This includes proving the formula of Candelas-de la Ossa-Green-Parkes hence completing the program of Candelas et al, Kontesevich, Manin, and Givental, to compute rigorously the instanton prepotential function for the quintic in $\\P^4$. We derive, among many other examples, the multiple cover formula for Gromov-Witten invariants of $\\P^1$, computed earlier by Morrison-Aspinwall and by Manin in different approaches. We also prove a formula for enumerating Euler classes which arise in the so-called local mirror symmetry for some noncompact Calabi-Yau manifolds. At the end we interprete an infinite dimensional transfor...

  20. Bosonization and mirror symmetry

    Science.gov (United States)

    Kachru, Shamit; Mulligan, Michael; Torroba, Gonzalo; Wang, Huajia

    2016-10-01

    We study bosonization in 2 +1 dimensions using mirror symmetry, a duality that relates pairs of supersymmetric theories. Upon breaking supersymmetry in a controlled way, we dynamically obtain the bosonization duality that equates the theory of a free Dirac fermion to QED3 with a single scalar boson. This duality may be used to demonstrate the bosonization duality relating an O (2 )-symmetric Wilson-Fisher fixed point to QED3 with a single Dirac fermion, Peskin-Dasgupta-Halperin duality, and the recently conjectured duality relating the theory of a free Dirac fermion to fermionic QED3 with a single flavor. Chern-Simons and BF couplings for both dynamical and background gauge fields play a central role in our approach. In the course of our study, we describe a "chiral" mirror pair that may be viewed as the minimal supersymmetric generalization of the two bosonization dualities.

  1. Contracture deformity

    Science.gov (United States)

    Deformity - contracture ... Contracture can be caused by any of the following: Brain and nervous system disorders, such as cerebral ... Follow your health care provider's instructions for treating contracture at home. Treatments may include: Doing exercises and ...

  2. Complex/Symplectic Mirrors

    CERN Document Server

    Chuang, W; Tomasiello, A; Chuang, Wu-yen; Kachru, Shamit; Tomasiello, Alessandro

    2005-01-01

    We construct a class of symplectic non--Kaehler and complex non--Kaehler string theory vacua, extending and providing evidence for an earlier suggestion by Polchinski and Strominger. The class admits a mirror pairing by construction. Comparing hints from a variety of sources, including ten--dimensional supergravity and KK reduction on SU(3)--structure manifolds, suggests a picture in which string theory extends Reid's fantasy to connect classes of both complex non-Kaehler and symplectic non-Kaehler manifolds.

  3. Mirrors Containing Biomimetic Shape-Control Actuators

    Science.gov (United States)

    Bar-Cohen, Yoseph; Mouroulis, Pantazis; Bao, Xiaoqi; Sherrit, Stewart

    2003-01-01

    Curved mirrors of a proposed type would comprise lightweight sheets or films containing integral, biologically inspired actuators for controlling their surface figures. These mirrors could be useful in such applications as collection of solar energy, focusing of radio beams, and (provided sufficient precision could be achieved) imaging. These mirrors were originally intended for use in outer space, but it should also be possible to develop terrestrial versions. Several prior NASA Tech Briefs articles have described a variety of approaches to the design of curved, lightweight mirrors containing integral shape-control actuators. The primary distinction between the present approach and the prior approaches lies in the actuator design concept, which involves shapes and movements reminiscent of those of a variety of small, multi-armed animals. The shape and movement of an actuator of this type can also be characterized as reminiscent of that of an umbrella. This concept can be further characterized as a derivative of that of multifinger grippers, the fingers of which are bimorph bending actuators (see Figure 1). The fingers of such actuators can be strips containing any of a variety of materials that have been investigated for use as actuators, including such electroactive polymers as ionomeric polymer/metal composites (IPMCs), ferroelectric polymers, and grafted elastomers. A mirror according to this proposal would be made from a sheet of one of the actuator composites mentioned above. The design would involve many variables, including the pre-curvature and stiffness of the mirror sheet, the required precision of figure control, the required range of variation in focal length (see Figure 2), the required precision of figure control for imaging or non-imaging use, the bending and twisting moments needed to effect the required deformations, and voltage-tomoment coefficients of the actuators, and the voltages accordingly required for actuation. A typical design would call

  4. The meter-class carbon fiber reinforced polymer mirror and segmented mirror telescope at the Naval Postgraduate School

    Science.gov (United States)

    Wilcox, Christopher; Fernandez, Bautista; Bagnasco, John; Martinez, Ty; Romeo, Robert; Agrawal, Brij

    2015-03-01

    The Adaptive Optics Center of Excellence for National Security at the Naval Postgraduate School has implemented a technology testing platform and array of facilities for next-generation space-based telescopes and imaging system development. The Segmented Mirror Telescope is a 3-meter, 6 segment telescope with actuators on its mirrors for system optical correction. Currently, investigation is being conducted in the use of lightweight carbon fiber reinforced polymer structures for large monolithic optics. Advantages of this material include lower manufacturing costs, very low weight, and high durability and survivability compared to its glass counterparts. Design and testing has begun on a 1-meter, optical quality CFRP parabolic mirror for the purpose of injecting collimated laser light through the SMT primary and secondary mirrors as well as the following aft optics that include wavefront sensors and deformable mirrors. This paper will present the design, testing, and usage of this CFRP parabolic mirror and the current path moving forward with this ever-evolving technology.

  5. Ground-Based VIS/NIR Reflectance Spectra of 25143 Itokawa: What Hayabusa will See and How Ground-Based Data can Augment Analyses

    Science.gov (United States)

    Vilas, Faith; Abell, P. A.; Jarvis, K. S.

    2004-01-01

    Planning for the arrival of the Hayabusa spacecraft at asteroid 25143 Itokawa includes consideration of the expected spectral information to be obtained using the AMICA and NIRS instruments. The rotationally-resolved spatial coverage the asteroid we have obtained with ground-based telescopic spectrophotometry in the visible and near-infrared can be utilized here to address expected spacecraft data. We use spectrophotometry to simulate the types of data that Hayabusa will receive with the NIRS and AMICA instruments, and will demonstrate them here. The NIRS will cover a wavelength range from 0.85 m, and have a dispersion per element of 250 Angstroms. Thus, we are limited in coverage of the 1.0 micrometer and 2.0 micrometer mafic silicate absorption features. The ground-based reflectance spectra of Itokawa show a large component of olivine in its surface material, and the 2.0 micrometer feature is shallow. Determining the olivine to pyroxene abundance ratio is critically dependent on the attributes of the 1.0- and 2.0 micrometer features. With a cut-off near 2,1 micrometer the longer edge of the 2.0- feature will not be obtained by NIRS. Reflectance spectra obtained using ground-based telescopes can be used to determine the regional composition around space-based spectral observations, and possibly augment the longer wavelength spectral attributes. Similarly, the shorter wavelength end of the 1.0 micrometer absorption feature will be partially lost to the NIRS. The AMICA filters mimic the ECAS filters, and have wavelength coverage overlapping with the NIRS spectral range. We demonstrate how merging photometry from AMICA will extend the spectral coverage of the NIRS. Lessons learned from earlier spacecraft to asteroids should be considered.

  6. Radiometric Modeling and Calibration of the Geostationary Imaging Fourier Transform Spectrometer (GIFTS)Ground Based Measurement Experiment

    Science.gov (United States)

    Tian, Jialin; Smith, William L.; Gazarik, Michael J.

    2008-01-01

    The ultimate remote sensing benefits of the high resolution Infrared radiance spectrometers will be realized with their geostationary satellite implementation in the form of imaging spectrometers. This will enable dynamic features of the atmosphere s thermodynamic fields and pollutant and greenhouse gas constituents to be observed for revolutionary improvements in weather forecasts and more accurate air quality and climate predictions. As an important step toward realizing this application objective, the Geostationary Imaging Fourier Transform Spectrometer (GIFTS) Engineering Demonstration Unit (EDU) was successfully developed under the NASA New Millennium Program, 2000-2006. The GIFTS-EDU instrument employs three focal plane arrays (FPAs), which gather measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The GIFTS calibration is achieved using internal blackbody calibration references at ambient (260 K) and hot (286 K) temperatures. In this paper, we introduce a refined calibration technique that utilizes Principle Component (PC) analysis to compensate for instrument distortions and artifacts, therefore, enhancing the absolute calibration accuracy. This method is applied to data collected during the GIFTS Ground Based Measurement (GBM) experiment, together with simultaneous observations by the accurately calibrated AERI (Atmospheric Emitted Radiance Interferometer), both simultaneously zenith viewing the sky through the same external scene mirror at ten-minute intervals throughout a cloudless day at Logan Utah on September 13, 2006. The accurately calibrated GIFTS radiances are produced using the first four PC scores in the GIFTS-AERI regression model. Temperature and moisture profiles retrieved from the PC-calibrated GIFTS radiances are verified against radiosonde measurements collected throughout the GIFTS sky measurement period. Using the GIFTS GBM calibration model, we compute the calibrated radiances from data

  7. A spectrum of shadowed mirroring.

    Science.gov (United States)

    Wanamaker, Melissa C

    2012-04-01

    The central focus of this paper is to explore and extend Kohut's theory of maternal mirroring and to place it within the current context of psychoanalytic thinking. Kohut believed a child must experience "positive" mirroring from his or her mother in infancy and beyond to ensure development of a healthy self. Kohut alludes, however, to a possible situation in which the mother's face, metaphorically a mirror, can appear "faceless" to her child. From this I have inferred the concept of what I shall call "shadowed mirroring." Clinical and literary examples show that distorted, "shadowed" mirroring appears on a spectrum, with passive mirroring at one end and hostile (either verbal or nonverbal) mirroring on the other; some individuals experience both. I then consider how "shadowed mirroring," especially hostile mirroring, can be understood within the twin contexts of the overall mother-child relationship and present-day Intersubjective/Relational thinking that is both bidirectional and co-constructed. Shadowed mirroring can lead to severe personality dysfunction along the borderline-narcissistic range, as well as to difficulties in the areas of identity formation, failure of self-cohesiveness, and the blunting of certain humane qualities like empathy.

  8. On reconciling ground-based with spaceborne normalized radar cross section measurements

    DEFF Research Database (Denmark)

    Baumgartner, Francois; Munk, Jens; Jezek, K C

    2002-01-01

    This study examines differences in the normalized radar cross section, derived from ground-based versus spaceborne radar data. A simple homogeneous half-space model, indicates that agreement between the two improves as 1) the distance from the scatterer is increased; and/or 2) the extinction...

  9. Precision simulation of ground-based lensing data using observations from space

    CERN Document Server

    Mandelbaum, Rachel; Leauthaud, Alexie; Massey, Richard J; Rhodes, Jason

    2011-01-01

    Current and upcoming wide-field, ground-based, broad-band imaging surveys promise to address a wide range of outstanding problems in galaxy formation and cosmology. Several such uses of ground-based data, especially weak gravitational lensing, require highly precise measurements of galaxy image statistics with careful correction for the effects of the point-spread function (PSF). In this paper, we introduce the SHERA (SHEar Reconvolution Analysis) software to simulate ground-based imaging data with realistic galaxy morphologies and observing conditions, starting from space-based data (from COSMOS, the Cosmological Evolution Survey) and accounting for the effects of the space-based PSF. This code simulates ground-based data, optionally with a weak lensing shear applied, in a model-independent way using a general Fourier space formalism. The utility of this pipeline is that it allows for a precise, realistic assessment of systematic errors due to the method of data processing, for example in extracting weak len...

  10. Analysis of the substorm trigger phase using multiple ground-based instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Kauristie, K.; Pulkkinen, T.I.; Pellinen, R.J. [Finnish Meteorological Institute, Helsinki (Finland)] [and others

    1995-08-01

    The authors discuss in detail the observation of an event of auroral activity fading during the trigger, or growth phase of a magnetic storm. This event was observed by all-sky cameras, EISCAT radar and magnetometers, riometers, and pulsation magnetometers, from ground based stations in Finland and Scandanavia. Based on their detailed analysis, they present a possible cause for the observed fading.

  11. Simulation of the imaging quality of ground-based telescopes affected by atmospheric disturbances

    Science.gov (United States)

    Ren, Yubin; Kou, Songfeng; Gu, Bozhong

    2014-08-01

    Ground-based telescope imaging model is developed in this paper, the relationship between the atmospheric disturbances and the ground-based telescope image quality is studied. Simulation of the wave-front distortions caused by atmospheric turbulences has long been an important method in the study of the propagation of light through the atmosphere. The phase of the starlight wave-front is changed over time, but in an appropriate short exposure time, the atmospheric disturbances can be considered as "frozen". In accordance with Kolmogorov turbulence theory, simulating atmospheric disturbances of image model based on the phase screen distorted by atmospheric turbulences is achieved by the fast Fourier transform (FFT). Geiger mode avalanche photodiode array (APD arrays) model is used for atmospheric wave-front detection, the image is achieved by inversion method of photon counting after the target starlight goes through phase screens and ground-based telescopes. Ground-based telescope imaging model is established in this paper can accurately achieve the relationship between the quality of telescope imaging and monolayer or multilayer atmosphere disturbances, and it is great significance for the wave-front detection and optical correction in a Multi-conjugate Adaptive Optics system (MCAO).

  12. Ground-based LIDAR: a novel approach to quantify fine-scale fuelbed characteristics

    Science.gov (United States)

    E.L. Loudermilk; J.K. Hiers; J.J. O’Brien; R.J. Mitchell; A. Singhania; J.C. Fernandez; W.P. Cropper; K.C. Slatton

    2009-01-01

    Ground-based LIDAR (also known as laser ranging) is a novel technique that may precisely quantify fuelbed characteristics important in determining fire behavior. We measured fuel properties within a south-eastern US longleaf pine woodland at the individual plant and fuelbed scale. Data were collected using a mobile terrestrial LIDAR unit at sub-cm scale for individual...

  13. Use of neural networks in ground-based aerosol retrievals from multi-angle spectropolarimetric observations

    NARCIS (Netherlands)

    Di Noia, A.; Hasekamp, O.P.; Harten, G. van; Rietjens, J.H.H.; Smit, J.M.; Snik, F.; Henzing, J.S.; Boer, J. de; Keller, C.U.; Volten, H.

    2015-01-01

    In this paper, the use of a neural network algorithm for the retrieval of the aerosol properties from ground-based spectropolarimetric measurements is discussed. The neural network is able to retrieve the aerosol properties with an accuracy that is almost comparable to that of an iterative retrieval

  14. Retrieval of liquid water cloud properties from ground-based remote sensing observations

    NARCIS (Netherlands)

    Knist, C.L.

    2014-01-01

    Accurate ground-based remotely sensed microphysical and optical properties of liquid water clouds are essential references to validate satellite-observed cloud properties and to improve cloud parameterizations in weather and climate models. This requires the evaluation of algorithms for retrieval of

  15. Ground-based remote sensing scheme for monitoring aerosol–cloud interactions (discussion)

    NARCIS (Netherlands)

    Sarna, K.; Russchenberg, H.W.J.

    2015-01-01

    A method for continuous observation of aerosol–cloud interactions with ground-based remote sensing instruments is presented. The main goal of this method is to enable the monitoring of cloud microphysical changes due to the changing aerosol concentration. We use high resolution measurements from lid

  16. Ground-based remote sensing scheme for monitoring aerosol-cloud interactions

    NARCIS (Netherlands)

    Sarna, K.; Russchenberg, H.W.J.

    2016-01-01

    A new method for continuous observation of aerosol–cloud interactions with ground-based remote sensing instruments is presented. The main goal of this method is to enable the monitoring of the change of the cloud droplet size due to the change in the aerosol concentration. We use high-resolution mea

  17. Low Power Ground-Based Laser Illumination for Electric Propulsion Applications

    Science.gov (United States)

    Lapointe, Michael R.; Oleson, Steven R.

    1994-01-01

    A preliminary evaluation of low power, ground-based laser powered electric propulsion systems is presented. A review of available and near-term laser, photovoltaic, and adaptive optic systems indicates that approximately 5-kW of ground-based laser power can be delivered at an equivalent one-sun intensity to an orbit of approximately 2000 km. Laser illumination at the proper wavelength can double photovoltaic array conversion efficiencies compared to efficiencies obtained with solar illumination at the same intensity, allowing a reduction in array mass. The reduced array mass allows extra propellant to be carried with no penalty in total spacecraft mass. The extra propellant mass can extend the satellite life in orbit, allowing additional revenue to be generated. A trade study using realistic cost estimates and conservative ground station viewing capability was performed to estimate the number of communication satellites which must be illuminated to make a proliferated system of laser ground stations economically attractive. The required number of satellites is typically below that of proposed communication satellite constellations, indicating that low power ground-based laser beaming may be commercially viable. However, near-term advances in low specific mass solar arrays and high energy density batteries for LEO applications would render the ground-based laser system impracticable.

  18. Asteroseismology of solar-type stars with Kepler: III. Ground-based data

    DEFF Research Database (Denmark)

    Karoff, Christoffer; Molenda-Żakowicz , J.

    2010-01-01

    We report on the ground-based follow-up program of spectroscopic and photometric observations of solar-like asteroseismic targets for the Kepler space mission. These stars constitute a large group of more than a thousand objects which are the subject of an intensive study by the Kepler Asteroseis...

  19. Relating the "mirrorness" of mirror neurons to their origins.

    Science.gov (United States)

    Kilner, James M; Friston, Karl J

    2014-04-01

    Ever since their discovery, mirror neurons have generated much interest and debate. A commonly held view of mirror neuron function is that they transform "visual information into knowledge," thus enabling action understanding and non-verbal social communication between con-specifics (Rizzolatti & Craighero 2004). This functionality is thought to be so important that it has been argued that mirror neurons must be a result of selective pressure.

  20. A Fast Method for Embattling Optimization of Ground-Based Radar Surveillance Network

    Science.gov (United States)

    Jiang, H.; Cheng, H.; Zhang, Y.; Liu, J.

    A growing number of space activities have created an orbital debris environment that poses increasing impact risks to existing space systems and human space flight. For the safety of in-orbit spacecraft, a lot of observation facilities are needed to catalog space objects, especially in low earth orbit. Surveillance of Low earth orbit objects are mainly rely on ground-based radar, due to the ability limitation of exist radar facilities, a large number of ground-based radar need to build in the next few years in order to meet the current space surveillance demands. How to optimize the embattling of ground-based radar surveillance network is a problem to need to be solved. The traditional method for embattling optimization of ground-based radar surveillance network is mainly through to the detection simulation of all possible stations with cataloged data, and makes a comprehensive comparative analysis of various simulation results with the combinational method, and then selects an optimal result as station layout scheme. This method is time consuming for single simulation and high computational complexity for the combinational analysis, when the number of stations increases, the complexity of optimization problem will be increased exponentially, and cannot be solved with traditional method. There is no better way to solve this problem till now. In this paper, target detection procedure was simplified. Firstly, the space coverage of ground-based radar was simplified, a space coverage projection model of radar facilities in different orbit altitudes was built; then a simplified objects cross the radar coverage model was established according to the characteristics of space objects orbit motion; after two steps simplification, the computational complexity of the target detection was greatly simplified, and simulation results shown the correctness of the simplified results. In addition, the detection areas of ground-based radar network can be easily computed with the

  1. Ground-Based Lidar Measurements During the CALIPSO and Twilight Zone (CATZ) Campaign

    Science.gov (United States)

    Berkoff, Timothy; Qian, Li; Kleidman, Richard; Stewart, Sebastian; Welton, Ellsworth; Li, Zhu; Holbem, Brent

    2008-01-01

    The CALIPSO and Twilight Zone (CATZ) field campaign was carried out between June 26th and August 29th of 2007 in the multi-state Maryland-Virginia-Pennsylvania region of the U.S. to study aerosol properties and cloud-aerosol interactions during overpasses of the CALIPSO satellite. Field work was conducted on selected days when CALIPSO ground tracks occurred in the region. Ground-based measurements included data from multiple Cimel sunphotometers that were placed at intervals along a segment of the CALIPSO ground-track. These measurements provided sky radiance and AOD measurements to enable joints inversions and comparisons with CALIPSO retrievals. As part of this activity, four ground-based lidars provided backscatter measurements (at 523 nm) in the region. Lidars at University of Maryland Baltimore County (Catonsville, MD) and Goddard Space Flight Center (Greenbelt, MD) provided continuous data during the campaign, while two micro-pulse lidar (MPL) systems were temporarily stationed at various field locations directly on CALIPSO ground-tracks. As a result, thirteen on-track ground-based lidar observations were obtained from eight different locations in the region. In some cases, nighttime CALIPSO coincident measurements were also obtained. In most studies reported to date, ground-based lidar validation efforts for CALIPSO rely on systems that are at fixed locations some distance away from the satellite ground-track. The CATZ ground-based lidar data provide an opportunity to examine vertical structure properties of aerosols and clouds both on and off-track simultaneously during a CALIPSO overpass. A table of available ground-based lidar measurements during this campaign will be presented, along with example backscatter imagery for a number of coincident cases with CALIPSO. Results indicate that even for a ground-based measurements directly on-track, comparisons can still pose a challenge due to the differing spatio-temporal properties of the ground and satellite

  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. Phase-Controlled Magnetic Mirror for Wavefront Correction

    Science.gov (United States)

    Hagopian, John; Wollack, Edward

    2011-01-01

    Typically, light interacts with matter via the electric field and interaction with weakly bound electrons. In a magnetic mirror, a patterned nanowire is fabricated over a metallic layer with a dielectric layer in between. Oscillation of the electrons in the nanowires in response to the magnetic field of incident photons causes a re-emission of photons and operation as a "magnetic mirror." By controlling the index of refraction in the dielectric layer using a local applied voltage, the phase of the emitted radiation can be controlled. This allows electrical modification of the reflected wavefront, resulting in a deformable mirror that can be used for wavefront control. Certain applications require wavefront quality in the few-nanometer regime, which is a major challenge for optical fabrication and alignment of mirrors or lenses. The use of a deformable magnetic mirror allows for a device with no moving parts that can modify the phase of incident light over many spatial scales, potentially with higher resolution than current approaches. Current deformable mirrors modify the incident wavefront by using nano-actuation of a substrate to physically bend the mirror to a desired shape. The purpose of the innovation is to modify the incident wavefront for the purpose of correction of fabrication and alignment-induced wavefront errors at the system level. The advanced degree of precision required for some applications such as gravity wave detection (LISA - Laser Interferometer Space Antenna) or planet finding (FKSI - Fourier-Kelvin Stellar Interferometer) requires wavefront control at the limits of the current state of the art. All the steps required to fabricate a magnetic mirror have been demonstrated. The modification is to apply a bias voltage to the dielectric layer so as to change the index of refraction and modify the phase of the reflected radiation. Light is reflected off the device and collected by a phase-sensing interferometer. The interferometer determines the

  5. SXI Prototype mirror mount

    Science.gov (United States)

    1995-01-01

    This final report describes the work performed from June 1993 to January 1995. The purpose of this contract was to provide optomechanical engineering and fabrication support to the Solar X-ray Imager (SXI) program in the areas of mirror, optical bench and camera assemblies of the telescope. The Center for Applied Optics (CAO) worked closely with the Optics and S&E technical staff of MSFC to develop and investigate the most viable and economical options for the design and fabrication of a number of parts for the various telescope assemblies. All the tasks under this delivery order have been successfully completed within budget and schedule.

  6. Look Into the Mirror

    Institute of Scientific and Technical Information of China (English)

    夏文虹

    2007-01-01

    Look into the mirror. Who is that girl I see, staring strange back at me? Is it a true myself or someone I have never known? Who am I? Why am I in this world? What am I going to do? So many times I questioned myself. I could never find a perfect answer. Why do I have to do such a lot of hard work? Why must I have so many exams? Why do I always read and read, write and write? Don't tell me it is the very life. Don't tell me these should be my happiness.

  7. Eavesdropping with a Mirror

    Institute of Scientific and Technical Information of China (English)

    JENNIFER LIM

    1994-01-01

    It was a custom in Yidu that on New Year’s Eve, people eavesdropped outside other people’s homes with a bronze mirror hidden in the bosom after reciting a rhyme to it. People believed that what they had heard would often fortell good or bad luck. A family named Zheng once lived in Yidu. The two sons of this family were both considered intellectuals, But the older son was eager to learn while the younger was lazy and sluggish. Their parents only liked the older son. Because of this, the old couple’s attitudes toward their two daughters-in-law were also

  8. Complex/Symplectic Mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Wu-yen; Kachru, Shamit; /Stanford U., ITP /SLAC; Tomasiello, Alessandro; /Stanford U., ITP

    2005-10-28

    We construct a class of symplectic non-Kaehler and complex non-Kaehler string theory vacua, extending and providing evidence for an earlier suggestion by Polchinski and Strominger. The class admits a mirror pairing by construction. Comparing hints from a variety of sources, including ten-dimensional supergravity and KK reduction on SU(3)-structure manifolds, suggests a picture in which string theory extends Reid's fantasy to connect classes of both complex non-Kaehler and symplectic non-Kaehler manifolds.

  9. Mirror symmetry II

    CERN Document Server

    Greene, Brian R

    1997-01-01

    Mirror symmetry has undergone dramatic progress during the last five years. Tremendous insight has been gained on a number of key issues. This volume surveys these results. Some of the contributions in this work have appeared elsewhere, while others were written specifically for this collection. The areas covered are organized into 4 sections, and each presents papers by both physicists and mathematicians. This volume collects the most important developments that have taken place in mathematical physics since 1991. It is an essential reference tool for both mathematics and physics libraries and for students of physics and mathematics.

  10. Foundry Microfabrication of Deformable Mirrors for Adaptive Optics

    Science.gov (United States)

    1998-04-28

    R. T. Howe, and A. P. Pisano, "Wafer-to-wafer transfer of microstrucrures for vacuum packaging ," Proceedings of the Solid-State Sensor and Actuator...Liang, R. Y. Howe, and A. P. Pisano, "Wafer-to-wafer transfer of microstructures for vacuum packaging ", in Proceedings of the Solid-State Sensor and

  11. Ultraflat Tip-Tilt-Piston MEMS Deformable Mirror Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal describes a Phase II SBIR project to develop high-resolution, ultraflat micromirror array devices using advanced silicon surface micromachining...

  12. Fabrication Process Development for Light Deformable Mirrors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This development is a collaborative effort between California Institute of Technology (Caltech) and the Jet Propulsion Laboratory (JPL). The fabrication is done...

  13. Enhanced Reliability MEMS Deformable Mirrors for Space Imaging Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of this project is to develop and demonstrate a reliable, fault-tolerant wavefront control system that will fill a critical technology gap in NASA's vision...

  14. Compact Low-Power Driver for Deformable Mirror Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal describes a new concept to drive MEMS DMs using low-power, high-voltage multiplexing. Compared to other reported approaches, the proposed architecture...

  15. Ronchi test for flat mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Estrada, N. [Instituto de Fisica, Universidad Autonoma de San Luis Potosi (Mexico); Engelfried, J. [Instituto de Fisica, Universidad Autonoma de San Luis Potosi (Mexico)]. E-mail: jurgen@ifisica.uaslp.mx; Morelos, A. [Instituto de Fisica, Universidad Autonoma de San Luis Potosi (Mexico)

    2005-11-11

    One of the RICHes in the velocity spectrometers of the proposed CKM experiment requires a flat mirror, situated in the high intensity kaon beam. To reduce the interaction background for the experiment, this mirror has to be as thin as possible. First glass prototypes were produced in Mexico. To test the surface quality of these prototypes, we extended the Ronchi method so flat mirrors can also be tested. We present the methods and report on results of our measurements.

  16. Focusing Mirror with Tunable Eccentricity

    CERN Document Server

    Stürmer, Moritz; Brunne, Jens; Wallrabe, Ulrike

    2013-01-01

    We present a new kind of varifocal mirror with independently adjustable curvatures in the major directions. For actuation we use two stacked piezo bending actuators with crossed in-plane polarization. This mirror can be used for example as an off-axis focusing device with tunable focal length and compensation for a variable angle of incidence or for coma correction. We demonstrate the prototype of such a mirror and characterize the mechanical deflection, as well as the focusing capabilities.

  17. Deformation microstructures

    DEFF Research Database (Denmark)

    Hansen, N.; Huang, X.; Hughes, D.A.

    2004-01-01

    Microstructural characterization and modeling has shown that a variety of metals deformed by different thermomechanical processes follows a general path of grain subdivision, by dislocation boundaries and high angle boundaries. This subdivision has been observed to very small structural scales...... of the order of 10 nm, produced by deformation under large sliding loads. Limits to the evolution of microstructural parameters during monotonic loading have been investigated based on a characterization by transmission electron microscopy. Such limits have been observed at an equivalent strain of about 10...

  18. Ground-based Hyperspectral Remote Sensing for Mapping Rock Alterations and Lithologies: Case Studies from Semail Ophiolite, Oman and Rush Springs Sandstone, Oklahoma

    Science.gov (United States)

    Sun, L.; Khan, S.; Hauser, D. L.; Glennie, C. L.; Snyder, C.; Okyay, U.

    2014-12-01

    This study used ground-based hyperspectral remote sensing data to map rock alterations and lithologies at Semail Ophiolite, Oman, as well as hydrocarbon-induced rock alterations at Cement, Oklahoma. The Samail Ophiolite exposed the largest, least-deformed, and the most-studied ophiolite in the world. Hydrocarbon seepages at Cement, Oklahoma brought hydrocarbons to the Rush Springs sandstones at surface, and generated rock alterations including bleaching of red beds, and carbonate cementation. Surficial expressions of rock alterations and different lithofacies are distinct from adjacent rocks, and can be detected by remote sensing techniques. Hyperspectral remote sensing acquires light intensity for hundreds of bands in a continuous electromagnetic spectrum from visible light to short-wave infrared radiation, and holds potential to characterize rocks with great precision. Ground-based hyperspectral study could scan the objects at close ranges thus provide very fine spatial resolutions (millimeters to centimeters). This study mapped all the major iconic outcrops of Semail ophiolite including pillow lava, sheeted dykes, layered gabbros, and peridotites. This study also identified surficial rock alterations induced by hydrocarbons at Cement, Oklahoma. Reddish-brown Rush Spring sandstones are bleached to pink, yellow, and gray colors; pore spaces in the sandstones have been filled with carbonate cementation. Laboratory spectroscopy was used to assist with mineral identification and classification in hyperspectral data. Terrestrial laser scanning (TLS) was used to provide high-accuracy spatial references. Principal component analysis, minimum noise fraction, spectral angle mapper, and band ratios are used in image processing. Combining lithological, remote sensing and geochemical data, this study built a model for petroleum seepage and related rock alterations, and provided a workflow for employing ground-based hyperspectral remote sensing techniques in petrological

  19. Water erosion as a cause for agricultural soil loss: modeling of dynamic processes using high-resolution ground based LiDAR measurements

    Science.gov (United States)

    Oz, Imri; Filin, Sagi; Assouline, Shmuel; Shtain, Zachi; Furman, Alexander

    2016-04-01

    Soil erosion by rainfall and water flow is a frequent natural geomorphic process shaping the earth's surface at various scales. Conventional agrotechnical methods enhance soil erosion at the field scale and are at the origin of the reduction of the upper soil layer depth. This reduction is expressed in two aspects: decrease of soil depth, mainly due to erosion, and the diminution of soil quality, mainly due to the loss of fine material, nutrients and organic matter. Rain events, not even the most extremes, cause detachment and transport of fertile soil rich in organic matter and nutrients away from the fields, filling and plugging drainage channels, blocking infrastructure and contaminating water sources. Empirical, semi-empirical and mechanistic models are available to estimate soil erosion by water flow and sediment transport (e.g. WEPP, KINEROSS, EUROSEM). Calibration of these models requires data measured at high spatial and temporal resolutions. Development of high-resolution measurement tools (for both spatial and temporal aspects) should improve the calibration of functions related to particles detachment and transport from the soil surface. In addition, despite the great impact of different tillage systems on the soil erosion process, the vast majority of the models ignore this fundamental factor. The objective of this study is to apply high-resolution ground-based LiDAR measurements to different tillage schemes and scales to improve the ability of models to accurately describe the process of soil erosion induced by rainfall and overland flow. Ground-based laser scans provide high resolution accurate and subtle geomorphic changes, as well as larger-scale deformations. As such, it allows frequent monitoring, so that even the effect of a single storm can be measured, thus improving the calibration of the erosion models. Preliminary results for scans made in the field show the potential and limitations of ground-based LiDAR, and at this point qualitatively can

  20. Design Study of an 8 Meter Monolithic Mirror UV/Optical Space Telescope

    Science.gov (United States)

    Stahl, H. Philip

    2008-01-01

    This paper will review a recent NASA MSFC preliminary study that demonstrated the feasibility of launching a 6 to 8 meter class monolithic primary mirror telescope to Sun-Earth L2 using an Ares V. The study started with the unique capabilities of the Ares V vehicle and examined the feasibility of launching a large aperture low cost low risk telescope based on a conventional ground based glass primary mirror. Specific technical areas studied included optical design; structural design/analysis including primary mirror support structure, sun shade and secondary mirror support structure; thermal analysis; launch vehicle performance and trajectory; spacecraft including structure, propulsion, GN & C, avionics, power systems and reaction wheels; operations & servicing, mass budget and system cost. The study telescope was an on-axis three-mirror anastigmatic design with a fine steering mirror. The observatory has a 100 arc-minute (8.4 X 12 arc-minutes) of diffraction limited field of view at a wavelength les than 500 nm. The study assumed that the primary mirror would be fabricated from an existing Schott Zerodur residual VLT blank edged to 6.2 meters, 175 mm thick at the edge with a mass of 11,000 kg. The entire mass budget for the observatory including primary mirror, structure, light baffle tube, instruments, space craft, avionics, etc. is less than 40,000 kg - a 33% mass margin on the Ares V's 60,000 kg Sun-Earth L2 capability. An 8 meter class observatory would have a total mass of less than 60,000 kg of which the primary mirror is the largest contributor.

  1. Effects of Forged Stock and Pure Aluminum Coating on Cryogenic Performance of Heat Treated Aluminum Mirrors

    Science.gov (United States)

    Toland, Ronald; Ohl, Raymond G.; Barthelmy, Michael P.; Zewari, S. Wahid; Greenhouse, Matthew A.; MacKenty, John W.

    2003-01-01

    In spite of its baseline mechanical stress relief, aluminum 6061-T651 harbors some residual stress that may relieve and distort mirror figure to unacceptable levels at cryogenic operating temperatures unless relieved during fabrication. Cryogenic instruments using aluminum mirrors for both ground-based and space IR astronomy have employed a variety of heat treatment formulae, with mixed results. We present the results of an on-going test program designed to empirically determine the effects of different stress relief procedures for aluminum mirrors. Earlier test results identified a preferred heat treatment for flat and spherical mirrors diamond turned from blanks cut out of Al6061-T651 plate stock. Further tests have been performed on mirrors from forged stock and one set from plate stock coated with Alumiplate(TM) aluminum coating to measure the effect of these variables on cryogenic performance. The mirrors are tested for figure error and radius of curvature at room temperature and at 80 K for three thermal cycles. We correlate the results of our optical testing with heat treatment and metallographic data.

  2. Deformation of rectangular thin glass plate coated with magnetostrictive material

    Science.gov (United States)

    Wang, Xiaoli; Yao, Youwei; Liu, Tianchen; Liu, Chian; Ulmer, M. P.; Cao, Jian

    2016-08-01

    As magnetic smart materials (MSMs), magnetostrictive materials have great potential to be selected as coating materials for lightweight x-ray telescope mirrors due to their capability to tune the mirror profile to the desired shape under a magnetic field. To realize this potential, it is necessary to study the deformation of the mirror substrate with the MSM coating subjected to a localized magnetic field. In this paper, an analytical model is developed to calculate the deformation of rectangular coated samples locally affected by magnetostrictive strains driven by an external magnetic field. As a specific case to validate the model, a square glass sample coated with MSMs is prepared, and its deformation is measured in a designed experimental setup by applying a magnetic field. The measured deformation of the sample is compared with the results calculated from the analytical model. The comparison results demonstrate that the analytical model is effective in calculating the deformation of a coated sample with the localized mismatch strains between the film and the substrate. In the experiments, different shape patterns of surface profile changes are achieved by varying the direction of the magnetic field. The analytical model and the experimental method proposed in this paper can be utilized to further guide the application of magnetostrictive coating to deformable lightweight x-ray mirrors in the future.

  3. Mirror development for CTA

    Science.gov (United States)

    Förster, A.; Doro, M.; Brun, P.; Canestrari, R.; Chadwick, P.; Font, L.; Ghigo, M.; Lorenz, E.; Mariotti, M.; Michalowski, J.; Niemiec, J.; Pareschi, G.; Peyaud, B.; Seweryn, K.

    2009-08-01

    The Cherenkov Telescope Array (CTA), currently in its early design phase, is a proposed new project for groundbased gamma-ray astronomy with at least 10 times higher sensitivity than current instruments. CTA is planned to consist of several tens of large Imaging Atmospheric Cherenkov Telescopes (IACTs) with a combined reflective surface of up to 10,000 m2. The challenge for the future CTA array is to develop lightweight and cost efficient mirrors with high production rates, good longterm durability and adequate optical properties. The technologies currently under investigation comprise different methods of carbon fibre/epoxy based substrates, sandwich concepts with cold-slumped surfaces made of thin float glass and different structural materials like aluminum honeycomb, glass foam or PU foam inside, and aluminum sandwich structures with either diamond milled surfaces or reflective foils. The current status of the mirror development for CTA will be summarized together with investigations on the improvement of the reflective surfaces and their protection against degradation.

  4. Haglund's Deformity

    Science.gov (United States)

    ... to follow the surgeon’s instructions for postsurgical care. Prevention To help prevent a recurrence of Haglund’s deformity: wear appropriate shoes; avoid shoes with a rigid heel back use arch supports or orthotic devices perform stretching exercises to prevent the Achilles tendon from tightening ...

  5. Shock Simulation of the Optics Mirror Assembly By Numerical Method

    Directory of Open Access Journals (Sweden)

    Mr. Brijeshkumar Patel

    2015-09-01

    Full Text Available Satellite faces many extreme types of loading throughout their life time from the harsh launch environment to the critical space environment. Launch load mainly dynamic is the main design concern for space structure. Shocks are the one of the most critical dynamic load occurs in spacecraft. Optics Mirror Assembly (OMA is used in the telescope of the satellite. The telescope performance relies on dimensional control & the geometric positioning of the mirror, pointing accuracy and controlled surface deformation of the mirror; Mirror fixation device (MFD is used for controlling all these factors. It should not distort due to launch loads mainly shocks as well as loads during operation of the telescope. In the present work an attempt has been made to perform experimental and computational analysis of the shock load on Optics Mirror Assembly. The FE modal for Shock Analysis purpose has been analysed with a specific Linear Transient Response Analysis in order to obtain the time history of acceleration in several output points. The analysis has been conducted over the time interval 0 to 62 ms and frequency band between 10 - 10 KHz. In order to verify the feasibility and reliability of the numerical (Implicit Finite Element Code, Nastran analysis, the numerical results obtained by Nastran have been compared with those obtained experimentally in the form of SRS. The overall outcome of the simulation method has proven its reliability in simulating Satellite payloads subjected to shocks.

  6. Active thermal figure control for the TOPS II primary mirror

    Science.gov (United States)

    Angel, Roger; Kang, Tae; Cuerden, Brian; Guyon, Olivier; Stahl, Phil

    2007-09-01

    TOPS (Telescope to Observe Planetary Systems) is the first coronagraphic telescope concept designed specifically to take advantage of Guyon's method of Phase Induced Amplitude Apodization PIAA).1 The TOPS primary mirror may incorporates active figure control to help achieve the desired wavefront control to approximately 1 angstrom RMS accurate across the spectral bandwidth. Direct correction of the primary figure avoids the need for a separate small deformable mirror. Because of Fresnel propagation, correction at a separate surface can introduce serious chromatic errors unless it is precisely conjugated to the primary. Active primary control also reduces complexity and mass and increases system throughput, and will likely enable a full system test to the 10-10 level in the 1 g environment before launch. We plan to use thermal actuators with no mechanical disturbance, using radiative heating or cooling fingers distributed inside the cells of a honeycomb mirror. The glass would have very small but finite coefficient of expansion of ~ 5x10 -8/C. Low order modes would be controlled by front-to-back gradients and high order modes by local rib expansion and contraction. Finite element models indicate that for a mirror with n cells up to n Zernike modes can be corrected to better than 90% fidelity, with still higher accuracy for the lower modes. An initial demonstration has been made with a borosilicate honeycomb mirror. Interferometric measurements show a single cell influence function with 300 nm stroke and ~5 minute time constant.

  7. Entry Dispersion Analysis for the Hayabusa Spacecraft using Ground Based Optical Observation

    CERN Document Server

    Yamaguchi, T; Yagi, M; Tholen, D J

    2011-01-01

    Hayabusa asteroid explorer successfully released the sample capsule to Australia on June 13, 2010. Since the Earth reentry phase of sample return was critical, many backup plans for predicting the landing location were prepared. This paper investigates the reentry dispersion using ground based optical observation as a backup observation for radiometric observation. Several scenarios are calculated and compared for the reentry phase of the Hayabusa to evaluate the navigation accuracy of the ground-based observation. The optical observation doesn't require any active reaction from a spacecraft, thus these results show that optical observations could be a steady backup strategy even if a spacecraft had some trouble. We also evaluate the landing dispersion of the Hayabusa only with the optical observation.

  8. Ground-based walking training improves quality of life and exercise capacity in COPD.

    Science.gov (United States)

    Wootton, Sally L; Ng, L W Cindy; McKeough, Zoe J; Jenkins, Sue; Hill, Kylie; Eastwood, Peter R; Hillman, David R; Cecins, Nola; Spencer, Lissa M; Jenkins, Christine; Alison, Jennifer A

    2014-10-01

    This study was designed to determine the effect of ground-based walking training on health-related quality of life and exercise capacity in people with chronic obstructive pulmonary disease (COPD). People with COPD were randomised to either a walking group that received supervised, ground-based walking training two to three times a week for 8-10 weeks, or a control group that received usual medical care and did not participate in exercise training. 130 out of 143 participants (mean±sd age 69±8 years, forced expiratory volume in 1 s 43±15% predicted) completed the study. Compared to the control group, the walking group demonstrated greater improvements in the St George's Respiratory Questionnaire total score (mean difference -6 points (95% CI -10- -2), pimproves quality of life and endurance exercise capacity in people with COPD.

  9. Nulling interferometry: performance comparison between space and ground-based sites for exozodiacal disc detection

    CERN Document Server

    Defrère, D; Foresto, V Coudé du; Danchi, W C; Hartog, R den

    2008-01-01

    Characterising the circumstellar dust around nearby main sequence stars is a necessary step in understanding the planetary formation process and is crucial for future life-finding space missions such as ESA's Darwin or NASA's Terrestrial Planet Finder (TPF). Besides paving the technological way to Darwin/TPF, the space-based infrared interferometers Pegase and FKSI (Fourier-Kelvin Stellar Interferometer) will be valuable scientific precursors in that respect. In this paper, we investigate the performance of Pegase and FKSI for exozodiacal disc detection and compare the results with ground-based nulling interferometers. Besides their main scientific goal (characterising hot giant extrasolar planets), Pegase and FKSI are very efficient in assessing within a few minutes the level of circumstellar dust in the habitable zone around nearby main sequence stars. They are capable of detecting exozodiacal discs respectively 5 and 1 time as dense as the solar zodiacal cloud and they outperform any ground-based instrumen...

  10. Techniques to extend the reach of ground based gravitational wave detectors

    Science.gov (United States)

    Dwyer, Sheila

    2016-03-01

    While the current generation of advanced ground based detectors will open the gravitational wave universe to observation, ground based interferometry has the potential to extend the reach of these observatories to high redshifts. Several techniques have the potential to improve the advanced detectors beyond design sensitivity, including the use of squeezed light, upgraded suspensions, and possibly new optical coatings, new test mass materials, and cryogenic suspensions. To improve the sensitivity by more than a factor of 10 compared to advanced detectors new, longer facilities will be needed. Future observatories capable of hosting interferometers 10s of kilometers long have the potential to extend the reach of gravitational wave astronomy to cosmological distances, enabling detection of binary inspirals from throughout the history of star formation.

  11. Ground-based near-infrared imaging of the HD141569 circumstellar disk

    CERN Document Server

    Boccaletti, A; Marchis, F; Hanh, J

    2003-01-01

    We present the first ground-based near-infrared image of the circumstellar disk around the post-Herbig Ae/Be star HD141569A initially detected with the HST. Observations were carried out in the near-IR (2.2 $\\mu$m) at the Palomar 200-inch telescope using the adaptive optics system PALAO. The main large scale asymmetric features of the disk are detected on our ground-based data. In addition, we measured that the surface brightness of the disk is slightly different than that derived by HST observations (at 1.1 $\\mu$m and 1.6 $\\mu$m). We interpret this possible color-effect in terms of dust properties and derive a minimal

  12. Validation of Aura OMI by Aircraft and Ground-Based Measurements

    Science.gov (United States)

    McPeters, R. D.; Petropavlovskikh, I.; Kroon, M.

    2006-12-01

    Both aircraft-based and ground-based measurements have been used to validate ozone measurements by the OMI instrument on Aura. Three Aura Validation Experiment (AVE) flights have been conducted, in November 2004 and June 2005 with the NASA WB57, and in January/February 2005 with the NASA DC-8. On these flights, validation of OMI was primarily done using data from the CAFS (CCD Actinic Flux Spectroradiometer) instrument, which is used to measure total column ozone above the aircraft. These measurements are used to differentiate changes in stratospheric ozone from changes in total column ozone. Also, changes in ozone over high clouds measured by OMI were checked in a flight over tropical storm Arlene on a flight on June 11th. Ground-based measurements were made during the SAUNA campaign in Sodankyla, Finland, in March and April 2006. Both total column ozone and the ozone vertical distribution were validated.

  13. REMOTE SENSING OF WATER VAPOR CONTENT USING GROUND-BASED GPS DATA

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Spatial and temporal resolution of water vapor content is useful in improving the accuracy of short-term weather prediction.Dense and continuously tracking regional GPS arrays will play an important role in remote sensing atmospheric water vapor content.In this study,a piecewise linear solution method was proposed to estimate the precipitable water vapor (PWV) content from ground-based GPS observations in Hong Kong.To evaluate the solution accuracy of the water vapor content sensed by GPS,the upper air sounding data (radiosonde) that are collected locally was used to calculate the precipitable water vapor during the same period.One-month results of PWV from both ground-based GPS sensing technique and radiosonde method are in agreement within 1~2 mm.This encouraging result will motivate the GPS meteorology application based on the establishment of a dense GPS array in Hong Kong.

  14. DEM extraction and its accuracy analysis with ground-based SAR interferometry

    Science.gov (United States)

    Dong, J.; Yue, J. P.; Li, L. H.

    2014-03-01

    Two altimetry models extracting DEM (Digital Elevation Model) with the GBSAR (Ground-Based Synthetic Aperture Radar) technology are studied and their accuracies are analyzed in detail. The approximate and improved altimetry models of GBSAR were derived from the spaceborne radar altimetry based on the principles of the GBSAR technology. The error caused by the parallel ray approximation in the approximate model was analyzed quantitatively, and the results show that the errors cannot be ignored for the ground-based radar system. For the improved altimetry model, the elevation error expression can be acquired by simulating and analyzing the error propagation coefficients of baseline length, wavelength, differential phase and range distance in the mathematical model. By analyzing the elevation error with the baseline and range distance, the results show that the improved altimetry model is suitable for high-precision DEM and the accuracy can be improved by adjusting baseline and shortening slant distance.

  15. Polishing technique for beryllium mirror

    Science.gov (United States)

    Froechtenigt, J. F.

    1976-01-01

    Performance tests, accomplished by inserting entire X ray telescope and polished mirror into vacuum line 67 m long and taking photographs of an X ray resolution source, indicate that polishing increases mirror efficiency from 0.06 percent for X rays at 0.8 nm and increases resolution from 15 to 3.75 arc-seconds.

  16. Investigating the long-term evolution of subtropical ozone profiles applying ground-based FTIR spectrometry

    OpenAIRE

    García, O.E.; Schneider, M; A. Redondas; Y. González; Hase, F.; Blumenstock, T.; Sepúlveda, E.

    2012-01-01

    This study investigates the long-term evolution of subtropical ozone profile time series (1999–2010) obtained from ground-based FTIR (Fourier Transform InfraRed) spectrometry at the Izaña Observatory ozone super-site. Different ozone retrieval strategies are examined, analysing the influence of an additional temperature retrieval and different constraints. The theoretical assessment reveals that the FTIR system is able to resolve four independent ozone layers with a precision of better than 6...

  17. Space Fence Ground-Based Radar System Increment 1 (Space Fence Inc 1)

    Science.gov (United States)

    2015-12-01

    Selected Acquisition Report (SAR) RCS: DD-A&T(Q&A)823-438 Space Fence Ground-Based Radar System Increment 1 (Space Fence Inc 1) As of FY 2017...11 Track to Budget 17 Cost and Funding 18 Low Rate Initial Production 23 Foreign Military Sales 24 Nuclear Costs 24 Unit Cost...Document CLIN - Contract Line Item Number CPD - Capability Production Document CY - Calendar Year DAB - Defense Acquisition Board DAE - Defense Acquisition

  18. Particle production during inflation and gravitational waves detectable by ground-based interferometers

    OpenAIRE

    Cook, Jessica L.; Sorbo, Lorenzo

    2011-01-01

    Inflation typically predicts a quasi scale-invariant spectrum of gravitational waves. In models of slow-roll inflation, the amplitude of such a background is too small to allow direct detection without a dedicated space-based experiment such as the proposed BBO or DECIGO. In this paper we note that particle production during inflation can generate a feature in the spectrum of primordial gravitational waves. We discuss the possibility that such a feature might be detected by ground-based laser...

  19. NASA Requirements for Ground-Based Pressure Vessels and Pressurized Systems (PVS). Revision C

    Science.gov (United States)

    Greulich, Owen Rudolf

    2017-01-01

    The purpose of this document is to ensure the structural integrity of PVS through implementation of a minimum set of requirements for ground-based PVS in accordance with this document, NASA Policy Directive (NPD) 8710.5, NASA Safety Policy for Pressure Vessels and Pressurized Systems, NASA Procedural Requirements (NPR) 8715.3, NASA General Safety Program Requirements, applicable Federal Regulations, and national consensus codes and standards (NCS).

  20. Comparison of NO2 vertical profiles from satellite and ground based measurements over Antarctica

    OpenAIRE

    Kulkarni, Pavan; Bortoli, Daniele; Costa, Maria João; Silva, Ana Maria; Ravegnani, Fabrizio; Giovanelli, Giorgio

    2011-01-01

    The Intercomparison of nitrogen dioxide (NO2) vertical profiles, derived from the satellite based HALogen Occultation Experiment (HALOE) measurements and from the ground based UV-VIS spectrometer GASCOD (Gas Analyzer Spectrometer Correlating Optical Differences) observations at the Mario Zucchelli Station (MZS), in Antarctica, are done for the first time. It is shown here that both datasets are in good agreement showing the same features in terms of magnitude, profile structure, a...

  1. The Gaia Era: synergy between space missions and ground based surveys

    CERN Document Server

    Vallenari, A

    2008-01-01

    The Gaia mission is expected to provide highly accurate astrometric, photometric, and spectroscopic measurements for about $10^9$ objects. Automated classification of detected sources is a key part of the data processing. Here a few aspects of the Gaia classification process are presented. Information from other surveys at longer wavelengths, and from follow-up ground based observations will be complementary to Gaia data especially at faint magnitudes, and will offer a great opportunity to understand our Galaxy.

  2. Generation-X mirror technology development plan and the development of adjustable x-ray optics

    Science.gov (United States)

    Reid, Paul B.; Davis, William; O'Dell, Stephen; Schwartz, Daniel A.; Tolier-McKinstry, Susan; Wilke, Rudeger H. T.; Zhang, William

    2009-08-01

    Generation-X is being studied as an extremely high resolution, very large area grazing incidence x-ray telescope. Under a NASA Advanced Mission Concepts Study, we have developed a technology plan designed to lead to the 0.1 arcsec (HPD) resolution adjustable optics with 50 square meters of effective area necessary to meet Generation-X requirements. We describe our plan in detail. In addition, we report on our development activities of adjustable grazing incidence optics via the fabrication of bimorph mirrors. We have successfully deposited thin-film piezo-electric material on the back surface of thin glass mirrors. We report on the electrical and mechanical properties of the bimorph mirrors. We also report on initial finite element modeling of adjustable grazing incidence mirrors; in particular, we examine the impact of how the mirrors are supported - the boundary conditions - on the deformations which can be achieved.

  3. Opto-thermal analysis of a lightweighted mirror for solar telescope

    CERN Document Server

    Banyal, Ravinder K; Chatterjee, S

    2013-01-01

    In this paper, an opto-thermal analysis of a moderately heated lightweighted solar telescope mirror is carried out using 3D finite element analysis (FEA). A physically realistic heat transfer model is developed to account for the radiative heating and energy exchange of the mirror with surroundings. The numerical simulations show the non-uniform temperature distribution and associated thermo-elastic distortions of the mirror blank clearly mimicking the underlying discrete geometry of the lightweighted substrate. The computed mechanical deformation data is analyzed with surface polynomials and the optical quality of the mirror is evaluated with the help of a ray-tracing software. The thermal print-through distortions are further shown to contribute to optical figure changes and mid-spatial frequency errors of the mirror surface. A comparative study presented for three commonly used substrate materials, namely, Zerodur, Pyrex and Silicon Carbide (SiC) is relevant to vast area of large optics requirements in gro...

  4. Cryogenic optical measurements of 12-segment-bonded carbon-fiber-reinforced silicon carbide composite mirror with support mechanism

    Science.gov (United States)

    Kaneda, Hidehiro; Nakagawa, Takao; Onaka, Takashi; Enya, Keigo; Makiuti, Sin'itirou; Takaki, Junji; Haruna, Masaki; Kume, Masami; Ozaki, Tsuyoshi

    2008-03-01

    A 720 mm diameter 12-segment-bonded carbon-fiber-reinforced silicon carbide (C/SiC) composite mirror has been fabricated and tested at cryogenic temperatures. Interferometric measurements show significant cryogenic deformation of the C/SiC composite mirror, which is well reproduced by a model analysis with measured properties of the bonded segments. It is concluded that the deformation is due mostly to variation in coefficients of thermal expansion among segments. In parallel, a 4-degree-of-freedom ball-bearing support mechanism has been developed for cryogenic applications. The C/SiC composite mirror was mounted on an aluminum base plate with the support mechanism and tested again. Cryogenic deformation of the mirror attributed to thermal contraction of the aluminum base plate via the support mechanism is highly reduced by the support, confirming that the newly developed support mechanism is promising for its future application to large-aperture cooled space telescopes.

  5. First-generation Science Cases for Ground-based Terahertz Telescopes

    CERN Document Server

    Hirashita, Hiroyuki; Matsushita, Satoki; Takakuwa, Shigehisa; Nakamura, Masanori; Asada, Keiichi; Liu, Hauyu Baobab; Urata, Yuji; Wang, Ming-Jye; Wang, Wei-Hao; Takahashi, Satoko; Tang, Ya-Wen; Chang, Hsian-Hong; Huang, Kuiyun; Morata, Oscar; Otsuka, Masaaki; Lin, Kai-Yang; Tsai, An-Li; Lin, Yen-Ting; Srinivasan, Sundar; Martin-Cocher, Pierre; Pu, Hung-Yi; Kemper, Francisca; Patel, Nimesh; Grimes, Paul; Huang, Yau-De; Han, Chih-Chiang; Huang, Yen-Ru; Nishioka, Hiroaki; Lin, Lupin Chun-Che; Zhang, Qizhou; Keto, Eric; Burgos, Roberto; Chen, Ming-Tang; Inoue, Makoto; Ho, Paul T P

    2015-01-01

    Ground-based observations at terahertz (THz) frequencies are a newly explorable area of astronomy for the next ten years. We discuss science cases for a first-generation 10-m class THz telescope, focusing on the Greenland Telescope as an example of such a facility. We propose science cases and provide quantitative estimates for each case. The largest advantage of ground-based THz telescopes is their higher angular resolution (~ 4 arcsec for a 10-m dish), as compared to space or airborne THz telescopes. Thus, high-resolution mapping is an important scientific argument. In particular, we can isolate zones of interest for Galactic and extragalactic star-forming regions. The THz windows are suitable for observations of high-excitation CO lines and [N II] 205 um lines, which are scientifically relevant tracers of star formation and stellar feedback. Those lines are the brightest lines in the THz windows, so that they are suitable for the initiation of ground-based THz observations. THz polarization of star-forming...

  6. Interactive dynamic three-dimensional scene for the ground-based three-dimensional display

    Science.gov (United States)

    Hou, Peining; Sang, Xinzhu; Guo, Nan; Chen, Duo; Yan, Binbin; Wang, Kuiru; Dou, Wenhua; Xiao, Liquan

    2016-10-01

    Three-dimensional (3D) displays provides valuable tools for many fields, such as scientific experiment, education, information transmission, medical imaging and physical simulation. Ground based 360° 3D display with dynamic and controllable scene can find some special applications, such as design and construction of buildings, aeronautics, military sand table and so on. It can be utilized to evaluate and visualize the dynamic scene of the battlefield, surgical operation and the 3D canvas of art. In order to achieve the ground based 3D display, the public focus plane should be parallel to the camera's imaging planes, and optical axes should be offset to the center of public focus plane in both vertical and horizontal directions. Virtual cameras are used to display 3D dynamic scene with Unity 3D engine. Parameters of virtual cameras for capturing scene are designed and analyzed, and locations of virtual cameras are determined by the observer's eye positions in the observing space world. An interactive dynamic 3D scene for ground based 360° 3D display is demonstrated, which provides high-immersion 3D visualization.

  7. Intercomparison of ground-based ozone and NO2 measurements during the MANTRA 2004 campaign

    Directory of Open Access Journals (Sweden)

    K. Strong

    2007-11-01

    Full Text Available The MANTRA (Middle Atmosphere Nitrogen TRend Assessment 2004 campaign took place in Vanscoy, Saskatchewan, Canada (52° N, 107° W from 3 August to 15 September, 2004. In support of the main balloon launch, a suite of five zenith-sky and direct-Sun-viewing UV-visible ground-based spectrometers was deployed, primarily measuring ozone and NO2 total columns. Three Fourier transform spectrometers (FTSs that were part of the balloon payload also performed ground-based measurements of several species, including ozone. Ground-based measurements of ozone and NO2 differential slant column densities from the zenith-viewing UV-visible instruments are presented herein. They are found to partially agree within NDACC (Network for the Detection of Atmospheric Composition Change standards for instruments certified for process studies and satellite validation. Vertical column densities of ozone from the zenith-sky UV-visible instruments, the FTSs, a Brewer spectrophotometer, and ozonesondes are compared, and found to agree within the combined error estimates of the instruments (15%. NO2 vertical column densities from two of the UV-visible instruments are compared, and are also found to agree within combined error (15%.

  8. Limitation of Ground-based Estimates of Solar Irradiance Due to Atmospheric Variations

    Science.gov (United States)

    Wen, Guoyong; Cahalan, Robert F.; Holben, Brent N.

    2003-01-01

    The uncertainty in ground-based estimates of solar irradiance is quantitatively related to the temporal variability of the atmosphere's optical thickness. The upper and lower bounds of the accuracy of estimates using the Langley Plot technique are proportional to the standard deviation of aerosol optical thickness (approx. +/- 13 sigma(delta tau)). The estimates of spectral solar irradiance (SSI) in two Cimel sun photometer channels from the Mauna Loa site of AERONET are compared with satellite observations from SOLSTICE (Solar Stellar Irradiance Comparison Experiment) on UARS (Upper Atmospheric Research Satellite) for almost two years of data. The true solar variations related to the 27-day solar rotation cycle observed from SOLSTICE are about 0.15% at the two sun photometer channels. The variability in ground-based estimates is statistically one order of magnitude larger. Even though about 30% of these estimates from all Level 2.0 Cimel data fall within the 0.4 to approx. 0.5% variation level, ground-based estimates are not able to capture the 27-day solar variation observed from SOLSTICE.

  9. Kepler and Ground-based Transits of the Exo-Neptune HAT-P-11b

    CERN Document Server

    Deming, Drake; Jackson, Brian; Peterson, Steven W; Agol, Eric; Knutson, Heather A; Jennings, Donald E; Haase, Flynn; Bays, Kevin

    2011-01-01

    We analyze 26 archival Kepler transits of the exo-Neptune HAT-P-11b, supplemented by ground-based transits observed in the blue (B-band) and near-IR (J-band). Both the planet and host star are smaller than previously believed; our analysis yields Rp=4.31 +/-0.06 Earth-radii, and Rs = 0.683 +/-0.009 solar radii, both about 3-sigma smaller than the discovery values. Our ground-based transit data at wavelengths bracketing the Kepler bandpass serve to check the wavelength dependence of stellar limb darkening, and the J-band transit provides a precise and independent constraint on the transit duration. Both the limb darkening and transit duration from our ground-based data are consistent with the new Kepler values for the system parameters. Our smaller radius for the planet implies that its gaseous envelope can be less extensive than previously believed, being very similar to the H-He envelope of GJ436b and Kepler-4b. HAT-P-11 is an active star, and signatures of star spot crossings are ubiquitous in the Kepler tr...

  10. Structure and evolution of Pluto's Atmosphere from ground-based stellar occultations between 2002 and 2015

    Science.gov (United States)

    Meza, Erick; Sicardy, Bruno; Rio de Janeiro occultation team, Granada occultation team, International Occultation and Timing Association

    2016-10-01

    Ground-Based stellar occultations probe Pluto's atmosphere from about 3 km altitude (~ 10 μbar pressure level) up to 260 km altitude (~0.1 μbar). Our main goal is to derive Pluto's atmosphere evolution using thirteen ground-based occultations observed between 2002 and 2015 (plus 2016, if available). We consistently analyze the light curves using the Dias et al. (ApJ 811, 53, 2015) model, and confirm the general pressure increase by a factor of about 1.5 between 2002 and 2015 and a factor of almost three between 1988 and 2015. Implications for Pluto's seasonal evolution will be briefly discussed in the context of the New Horizons (NH) findings.Ground-based-derived temperature profiles will be compared with NH's results, where we use new temperature boundary conditions in our inversion procedures, as given by NH near 260 km altitude. Although the profiles reasonably agree, significant discrepancies are observed both in the deeper stratospheric zone (altitude topographic features revealed by NH.Finally, possible correlations between spike activity in the occultation light-curves and local underlying presence of free nitrogen ice terrains will be investigated.Part of the research leading to these results has received funding from the European Research Council under the European Community's H2020 (2014-2020/ ERC Grant Agreement n 669416 "LUCKY STAR").

  11. Flow Characteristics of Tidewater Glaciers in Greenland and Alaska using Ground-Based LiDAR

    Science.gov (United States)

    Finnegan, D. C.; Stearns, L. A.; Hamilton, G. S.; O'Neel, S.

    2010-12-01

    LiDAR scanning systems have been employed to characterize and quantify multi-temporal glacier and ice sheet changes for nearly three decades. Until recently, LiDAR scanning systems were limited to airborne and space-based platforms which come at a significant cost to deploy and are limited in spatial and temporal sampling capabilities necessary to compare with in-situ field measurements. Portable ground-based LiDAR scanning systems are now being used as a glaciological tool. We discuss research efforts to employ ground-based near-infrared LiDAR systems at two differing tidewater glacier systems in the spring of 2009; Helheim Glacier in southeast Greenland and Columbia Glacier in southeast Alaska. Preliminary results allow us to characterize short term displacement rates and detailed observations of calving processes. These results highlight the operational limitations and capabilities of commercially available LiDAR systems, and allow us to identify optimal operating characteristics for monitoring small to large-scale tidewater glaciers in near real-time. Furthermore, by identifying the operational limitations of these sensors it allows for optimal design characteristics of new sensors necessary to meet ground-based calibration and validation requirements of ongoing scientific missions.

  12. Phase-coherent mapping of gravitational-wave backgrounds using ground-based laser interferometers

    CERN Document Server

    Romano, Joseph D; Cornish, Neil J; Gair, Jonathan; Mingarelli, Chiara M F; van Haasteren, Rutger

    2015-01-01

    We extend the formalisms developed in Gair et al. and Cornish and van Haasteren to create maps of gravitational-wave backgrounds using a network of ground-based laser interferometers. We show that in contrast to pulsar timing arrays, which are insensitive to half of the gravitational-wave sky (the curl modes), a network of ground-based interferometers is sensitive to both the gradient and curl components of the background. The spatial separation of a network of interferometers, or of a single interferometer at different times during its rotational and orbital motion around the Sun, allows for recovery of both components. We derive expressions for the response functions of a laser interferometer in the small-antenna limit, and use these expressions to calculate the overlap reduction function for a pair of interferometers. We also construct maximum-likelihood estimates of the + and x-polarization modes of the gravitational-wave sky in terms of the response matrix for a network of ground-based interferometers, e...

  13. A Ground-Based Array to Observe Geospace Electrodynamics During Adverse Space Weather Conditions

    Science.gov (United States)

    Sojka, J. J.; Eccles, J. V.; Rice, D.

    2004-05-01

    Geomagnetic Storms occur with surprising frequency and create adverse space weather conditions. During these periods, our knowledge and ability to specify or forecast in adequate detail for user needs is negligible. Neither experimental observations nor theoretical developments have made a significant new impact on the problem for over two decades. Although we can now map Total Electron Content (TEC) in the ionosphere over a continent with sufficient resolution to see coherent long-lived structures, these do not provide constraints on the geospace electrodynamics that is at the heart of our lack of understanding. We present arguments for the need of a continental deployment of ground-based sensors to stepwise advance our understanding of the geospace electrodynamics when it is most adverse from a space weather perspective and also most frustrating from an understanding of Magnetosphere-Ionosphere coupling. That a continental-scale deployment is more productive at addressing the problem than a realizable global distribution is shown. Each measurement is discussed from the point-of-view of either providing new knowledge or becoming a key for future real-time specification and forecasting for user applications. An example of a storm database from one mid-latitude station for the 31 March 2002 is used as a conceptual point in a ground-based array. The presentation focuses on scientific questions that have eluded a quantitative solution for over three decades and view a ground-based array as an "IGY" type of catalyst for answering these questions.

  14. Mirroring patients – or not

    DEFF Research Database (Denmark)

    Davidsen, Annette Sofie; Fosgerau, Christina Fogtmann

    2015-01-01

    on studies of imitative behaviour within linguistics and psychology, we argue that interactional mirroring is an important aspect of displaying implicit mentalization. We aimed to explore if, and in that case how, mirroring is displayed by general practitioners (GPs) and psychiatrists in consultations...... with patients with depression. We wanted to see how implicit mentalizing unfolds in physician–patient interactions. Consultations were videorecorded and analysed within the framework of conversation analysis. GPs and psychiatrists differed substantially in their propensity to mirror body movements and verbal...... and acoustic features of speech. GPs mirrored their patients more than psychiatrists in all modalities and were more flexible in their interactional behaviour. Psychiatrists seemed more static, regardless of the emotionality displayed by patients. Implicitly mirroring and attuning to patients could signify...

  15. Resonance MEMS mirrors design considerations

    Science.gov (United States)

    Sourani, S.

    2010-02-01

    Resonance MEMS mirrors are widely used today for many applications such as barcode scanners and personalprojectors. bTendo manufactures Personal Projection Engines on two types of mirrors: 1. Resonance mirrors for horizontal scanning 2. Linear mirrors for vertical scanning In this lecture we will discuss the "Energy Balance" and start-up conditions for resonance mirrors. We will derive the conditions for start-up as well as the predicted curve of θ(v): (see manuscript for equation) We will show simulation results in the time domain that prove the validity of the last equation. Finite element simulation could be used to calculate the comb capacitance and to predict the performance of a new structure.

  16. IXO glass mirrors development in Europe

    Science.gov (United States)

    Pareschi, G.; Basso, S.; Bavdaz, M.; Citterio, O.; Civitani, M. M.; Conconi, P.; Gallieni, D.; Ghigo, M.; Martelli, F.; Parodi, G.; Proserpio, L.; Sironi, G.; Spiga, D.; Tagliaferri, G.; Tintori, M.; Wille, E.; Zambra, A.

    2011-09-01

    The mirrors of the International X-ray Observatory (IXO) were based on of a large number of high quality segments, aiming at achieving a global spatial resolution better than 5 arcsec (HEW). A study concerning the slumping of thin glass foils for the IXO mirrors is under development in Europe, funded by ESA and led by the Brera Observatory and is continuing even after that the programhas been descoped, in the perspective of using the technology under development for other future missions. After a preliminary trade-off study, we have focused our the effort on the "Direct" slumping approach, based on the use of convex moulds. In this case during the thermal cycle the optical surface of the glass is in direct contact with the mould surface. The thin plates are made of thin glass sheets (0.4 mm thick), with a reflecting area of 200 mm × 200 mm. The adopted integration process foresees the use of reinforcing ribs for bonding together the plates and forming in that way a rigid and stiff stack of segmented mirror shells; the stack is supported by a thick backplane. During the bonding process the plates are constrained to stay in close contact with the surface of the master (i.e. the same mould used for the hot slumping process) by the application of vacuum pump suction. In this way the spring-back deformations and low frequency errors still present on the foil profile after slumping can be corrected. In this paper we will give an overview and a status report of the project.

  17. First results of the two square meters multilayer glass composite mirror design proposed for the Cherenkov Telescope Array developed at INFN

    CERN Document Server

    Schultz, C; Lessio, L; Mariotti, M; Rando, R

    2015-01-01

    The Cherenkov Telescope Array (CTA) is a future ground-based gamma-ray astronomy detector that will consist of more than 100 Imaging Atmospheric Cherenkov Telescopes of different sizes. The total reflective surface of roughly 10 000 m$^2$ requires unprecedented technological efforts towards a cost-efficient production of light-weight and reliable mirror substrates at high production rate. We report on a new mirror concept proposed for CTA developed by INFN, which is based on the replication from a spherical convex mold under low pressure. The mirror substrate is an open structure design made by thin glass layers at the mirror's front and rear interspaced by steel cylinders. A first series of nominal size mirrors has been produced, for which we discuss the optical properties in terms of radius of curvature and focusing power.

  18. Mirror man: a case of skilled deliberate mirror writing.

    Science.gov (United States)

    McIntosh, Robert D; De Lucia, Natascia; Della Sala, Sergio

    2014-01-01

    Mirror writing is a striking behaviour that is common in children and can reemerge in adults following brain damage. Skilled deliberate mirror writing has also been reported, but only anecdotally. We provide the first quantitative study of skilled deliberate mirror writing. K.B. can write forward or backward, vertically upright or inverted, with the hands acting alone or simultaneously. K.B. is predominantly left handed, but writes habitually with his right hand. Of his writing formats, his left hand mirror writing is by far the most similar in style to his normal handwriting. When writing bimanually, he performs better when his two hands make mirror-symmetrical movements to write opposite scripts than if they move in the same direction to write similar scripts. He has no special facility for reading mirrored text. These features are consistent with prior anecdotal cases and support a motor basis for K.B.'s ability, according to which his skilled mirror writing results from the left hand execution of a low-level motor program for a right hand abductive writing action. Our methods offer a novel framework for investigating the sharing of motor representations across effectors.

  19. Comparison of Thermal Structure Results from Venus Express and Ground Based Observations since Vira

    Science.gov (United States)

    Limaye, Sanjay

    2016-07-01

    An international team was formed in 2013 through the International Space Studies Institute (Bern, Switzerland) to compare recent results of the Venus atmospheric thermal structure from spacecraft and ground based observations made since the Venus International Reference Atmosphere (VIRA) was developed (Kliore et al., 1985, Keating et al., 1985). Five experiments on European Space Agency's Venus Express orbiter mission have yielded results on the atmospheric structure during is operational life (April 2006 - November 2014). Three of these were from occultation methods: at near infrared wavelengths from solar occultations, (SOIR, 70 - 170 km), at ultraviolet wavelengths from stellar occultations (SPICAV, 90-140 km), and occultation of the VEx-Earth radio signal (VeRa, 40-90 km). In-situ drag measurements from three different techniques (accelerometry, torque, and radio tracking, 130 - 200 km) were also obtained using the spacecraft itself while passive infrared remote sensing was used by the VIRTIS experiment (70 - 120 km). The only new data in the -40-70 km altitude range are from radio occultation, as no new profiles of the deep atmosphere have been obtained since the VeGa 2 lander measurements in 1985 (not included in VIRA). Some selected ground based results available to the team were also considered by team in the inter comparisons. The temperature structure in the lower thermosphere from disk resolved ground based observations (except for one ground based investigation), is generally consistent with the Venus Express results. These experiments sampled at different periods, at different locations and at different local times and have different vertical and horizontal resolution and coverage. The data were therefore binned in latitude and local time bins and compared, ignoring temporal variations over the life time of the Venus Express mission and assumed north-south symmetry. Alternating warm and cooler layers are present in the 120-160 altitude range in results

  20. Mirror symmetry, toric branes and topological string amplitudes as polynomials

    Energy Technology Data Exchange (ETDEWEB)

    Alim, Murad

    2009-07-13

    The central theme of this thesis is the extension and application of mirror symmetry of topological string theory. The contribution of this work on the mathematical side is given by interpreting the calculated partition functions as generating functions for mathematical invariants which are extracted in various examples. Furthermore the extension of the variation of the vacuum bundle to include D-branes on compact geometries is studied. Based on previous work for non-compact geometries a system of differential equations is derived which allows to extend the mirror map to the deformation spaces of the D-Branes. Furthermore, these equations allow the computation of the full quantum corrected superpotentials which are induced by the D-branes. Based on the holomorphic anomaly equation, which describes the background dependence of topological string theory relating recursively loop amplitudes, this work generalizes a polynomial construction of the loop amplitudes, which was found for manifolds with a one dimensional space of deformations, to arbitrary target manifolds with arbitrary dimension of the deformation space. The polynomial generators are determined and it is proven that the higher loop amplitudes are polynomials of a certain degree in the generators. Furthermore, the polynomial construction is generalized to solve the extension of the holomorphic anomaly equation to D-branes without deformation space. This method is applied to calculate higher loop amplitudes in numerous examples and the mathematical invariants are extracted. (orig.)

  1. Improvements in analysis techniques for segmented mirror arrays

    Science.gov (United States)

    Michels, Gregory J.; Genberg, Victor L.; Bisson, Gary R.

    2016-08-01

    The employment of actively controlled segmented mirror architectures has become increasingly common in the development of current astronomical telescopes. Optomechanical analysis of such hardware presents unique issues compared to that of monolithic mirror designs. The work presented here is a review of current capabilities and improvements in the methodology of the analysis of mechanically induced surface deformation of such systems. The recent improvements include capability to differentiate surface deformation at the array and segment level. This differentiation allowing surface deformation analysis at each individual segment level offers useful insight into the mechanical behavior of the segments that is unavailable by analysis solely at the parent array level. In addition, capability to characterize the full displacement vector deformation of collections of points allows analysis of mechanical disturbance predictions of assembly interfaces relative to other assembly interfaces. This capability, called racking analysis, allows engineers to develop designs for segment-to-segment phasing performance in assembly integration, 0g release, and thermal stability of operation. The performance predicted by racking has the advantage of being comparable to the measurements used in assembly of hardware. Approaches to all of the above issues are presented and demonstrated by example with SigFit, a commercially available tool integrating mechanical analysis with optical analysis.

  2. Advanced Mirror & Modelling Technology Development

    Science.gov (United States)

    Effinger, Michael; Stahl, H. Philip; Abplanalp, Laura; Maffett, Steven; Egerman, Robert; Eng, Ron; Arnold, William; Mosier, Gary; Blaurock, Carl

    2014-01-01

    The 2020 Decadal technology survey is starting in 2018. Technology on the shelf at that time will help guide selection to future low risk and low cost missions. The Advanced Mirror Technology Development (AMTD) team has identified development priorities based on science goals and engineering requirements for Ultraviolet Optical near-Infrared (UVOIR) missions in order to contribute to the selection process. One key development identified was lightweight mirror fabrication and testing. A monolithic, stacked, deep core mirror was fused and replicated twice to achieve the desired radius of curvature. It was subsequently successfully polished and tested. A recently awarded second phase to the AMTD project will develop larger mirrors to demonstrate the lateral scaling of the deep core mirror technology. Another key development was rapid modeling for the mirror. One model focused on generating optical and structural model results in minutes instead of months. Many variables could be accounted for regarding the core, face plate and back structure details. A portion of a spacecraft model was also developed. The spacecraft model incorporated direct integration to transform optical path difference to Point Spread Function (PSF) and between PSF to modulation transfer function. The second phase to the project will take the results of the rapid mirror modeler and integrate them into the rapid spacecraft modeler.

  3. LSST primary/tertiary monolithic mirror

    Science.gov (United States)

    Sebag, J.; Gressler, W.; Liang, M.; Neill, D.; Araujo-Hauck, C.; Andrew, J.; Angeli, G.; Cho, M.; Claver, C.; Daruich, F.; Gessner, C.; Hileman, E.; Krabbendam, V.; Muller, G.; Poczulp, G.; Repp, R.; Wiecha, O.; Xin, B.; Kenagy, K.; Martin, H. M.; Tuell, M. T.; West, S. C.

    2016-08-01

    At the core of the Large Synoptic Survey Telescope (LSST) three-mirror optical design is the primary/tertiary (M1M3) mirror that combines these two large mirrors onto one monolithic substrate. The M1M3 mirror was spin cast and polished at the Steward Observatory Mirror Lab at The University of Arizona (formerly SOML, now the Richard F. Caris Mirror Lab at the University of Arizona (RFCML)). Final acceptance of the mirror occurred during the year 2015 and the mirror is now in storage while the mirror cell assembly is being fabricated. The M1M3 mirror will be tested at RFCML after integration with its mirror cell before being shipped to Chile.

  4. Tandem mirror and field-reversed mirror experiments

    Energy Technology Data Exchange (ETDEWEB)

    Coensgen, F.H.; Simonen, T.C.; Turner, W.C.

    1979-08-21

    This paper is largely devoted to tandem mirror and field-reversed mirror experiments at the Lawrence Livermore Laboratory (LLL), and briefly summarizes results of experiments in which field-reversal has been achieved. In the tandem experiment, high-energy, high-density plasmas (nearly identical to 2XIIB plasmas) are located at each end of a solenoid where plasma ions are electrostatically confined by the high positive poentials arising in the end plug plasma. End plug ions are magnetically confined, and electrons are electrostatically confined by the overall positive potential of the system. The field-reversed mirror reactor consists of several small field-reversed mirror plasmas linked together for economic reasons. In the LLL Beta II experiment, generation of a field-reversed plasma ring will be investigated using a high-energy plasma gun with a transverse radial magnetic field. This plasma will be further heated and sustained by injection of intense, high-energy neutral beams.

  5. MIRROR MOVEMENT: A CASE REPORT

    Directory of Open Access Journals (Sweden)

    AA. Momen

    2008-11-01

    Full Text Available Mirror movement is an interesting but often overlooked neurological soft sign;these movements are described as simultaneous contralateral, involuntary, identical movements that accompany voluntary movements. This neurologic problem is very rarely seen in children; in familial cases there is a positive history of these movements in parents, diminishing with time. Here, we have presented the case of an 11-year old girl with mirror movements in her upper limbs which interfered with her hand writing. Her neurological examination revealed normal results. In this report, we have tried to explain some of the pathophysiologic mechanisms related to these abnormal movements.Keywords:Mirror Movements, Children, Soft neurologic sign

  6. Theta functions and mirror symmetry

    CERN Document Server

    Gross, Mark

    2012-01-01

    This is a survey covering aspects of varied work of the authors with Mohammed Abouzaid, Paul Hacking, and Sean Keel. While theta functions are traditionally canonical sections of ample line bundles on abelian varieties, we motivate, using mirror symmetry, the idea that theta functions exist in much greater generality. This suggestion originates with the work of the late Andrei Tyurin. We outline how to construct theta functions on the degenerations of varieties constructed in previous work of the authors, and then explain applications of this construction to homological mirror symmetry and constructions of broad classes of mirror varieties.

  7. Edificio Daily Mirror

    Directory of Open Access Journals (Sweden)

    Williams, Owen

    1963-07-01

    Full Text Available The building has 18 levels. The Press occupies the 4 basement floors. The ground floor is taken up with the entrance hall, and an indoor carriage way. A snack bar and the telephone operators are situated on the second floor. The production department and the medical services are located on the third storey, whilst the fourth is occupied by the offices and library. The fifth floor is the beginning of the higher section of the building. This floor and up to including the 11th floor are devoted to office space, except for the 10th storey, which contains the office apartments of the directors and the Council Chamber. Equipment related to various services of the building is housed on the 12th storey. Finally, this tall building constitutes a fine landmark in the London skyline. The Daily Mirror building is outstanding for the appropriate nature, the completeness and the quality of its installations, which thus provide the most widely read paper in the world with outstandingly efficient offices.Este edificio consta de 18 plantas. El cuerpo de Prensa se aloja en los cuatro sótanos; los vestíbulos de entrada y una calzada interior para vehículos se hallan en la planta baja; la primera alberga un snack-bar y centralita telefónica; la segunda, el departamento de producción y centro de asistencia médica, y la tercera, las oficinas y biblioteca principales. La cuarta planta señala el comienzo del bloque alto; esta planta, junto con las quinta, sexta, séptima, octava y décima, están dedicadas a oficinas. La novena contiene las oficinas-apartamentos de los directores y salas de Consejo, y la undécima, la maquinaria para las diversas instalaciones del edificio. La elevada torre constituye un grandioso hito de referencia en esta zona de Londres. El «Daily Mirror» se distingue por el acierto, número y perfección de sus instalaciones, que proporcionan, al periódico de mayor actualidad mundial, las más adecuadas y amplias oficinas modernas.

  8. Evanescent Wave Atomic Mirror

    Science.gov (United States)

    Ghezali, S.; Taleb, A.

    2008-09-01

    A research project at the "Laboratoire d'électronique quantique" consists in a theoretical study of the reflection and diffraction phenomena via an atomic mirror. This poster presents the principle of an atomic mirror. Many groups in the world have constructed this type of atom optics experiments such as in Paris-Orsay-Villetaneuse (France), Stanford-Gaithersburg (USA), Munich-Heidelberg (Germany), etc. A laser beam goes into a prism with an incidence bigger than the critical incidence. It undergoes a total reflection on the plane face of the prism and then exits. The transmitted resulting wave out of the prism is evanescent and repulsive as the frequency detuning of the laser beam compared to the atomic transition δ = ωL-ω0 is positive. The cold atomic sample interacts with this evanescent wave and undergoes one or more elastic bounces by passing into backward points in its trajectory because the atoms' kinetic energy (of the order of the μeV) is less than the maximum of the dipolar potential barrier ℏΩ2/Δ where Ω is the Rabi frequency [1]. In fact, the atoms are cooled and captured in a magneto-optical trap placed at a distance of the order of the cm above the prism surface. The dipolar potential with which interact the slow atoms is obtained for a two level atom in a case of a dipolar electric transition (D2 Rubidium transition at a wavelength of 780nm delivered by a Titane-Saphir laser between a fundamental state Jf = l/2 and an excited state Je = 3/2). This potential is corrected by an attractive Van der Waals term which varies as 1/z3 in the Lennard-Jones approximation (typical atomic distance of the order of λ0/2π where λ0 is the laser wavelength) and in 1/z4 if the distance between the atom and its image in the dielectric is big in front of λ0/2π. This last case is obtained in a quantum electrodynamic calculation by taking into account an orthornormal base [2]. We'll examine the role of spontaneous emission for which the rate is inversely

  9. Responder fast steering mirror

    Science.gov (United States)

    Bullard, Andrew; Shawki, Islam

    2013-10-01

    Raytheon Space and Airborne Systems (SAS) has designed, built and tested a 3.3-inch diameter fast steering mirror (FSM) for space application. This 2-axis FSM operates over a large angle (over 10 degree range), has a very high servo bandwidth (over 3.3 Khz closed loop bandwidth), has nanoradian-class noise, and is designed to support microradian class line of sight accuracy. The FSM maintains excellent performance over large temperature ranges (which includes wave front error) and has very high reliability with the help of fully redundant angle sensors and actuator circuits. The FSM is capable of achieving all its design requirements while also being reaction-compensated. The reaction compensation is achieved passively and does not need a separate control loop. The FSM has undergone various environmental testing which include exported forces and torques and thermal vacuum testing that support the FSM design claims. This paper presents the mechanical design and test results of the mechanism which satisfies the rigorous vacuum and space application requirements.

  10. Tinbergen on mirror neurons.

    Science.gov (United States)

    Heyes, Cecilia

    2014-01-01

    Fifty years ago, Niko Tinbergen defined the scope of behavioural biology with his four problems: causation, ontogeny, survival value and evolution. About 20 years ago, there was another highly significant development in behavioural biology-the discovery of mirror neurons (MNs). Here, I use Tinbergen's original four problems (rather than the list that appears in textbooks) to highlight the differences between two prominent accounts of MNs, the genetic and associative accounts; to suggest that the latter provides the defeasible 'best explanation' for current data on the causation and ontogeny of MNs; and to argue that functional analysis, of the kind that Tinbergen identified somewhat misleadingly with studies of 'survival value', should be a high priority for future research. In this kind of functional analysis, system-level theories would assign MNs a small, but potentially important, role in the achievement of action understanding-or another social cognitive function-by a production line of interacting component processes. These theories would be tested by experimental intervention in human and non-human animal samples with carefully documented and controlled developmental histories.

  11. Study on the support technology of the light-weighted mirror

    Science.gov (United States)

    Zhu, Nengbing; QI, Bo; Ren, Ge; Zhu, Fuyin; Ai, Zhiwei

    2016-10-01

    To reduce the surface deformation of a space remote sensor mirror in space environments, a flexible supporting structure of space mirror is designed to improve the surface accuracy of mirror under operating conditions, making the mirror in good thermal dimensional stability and the structure stiffness meet the requirements of mechanics at the same time. Using the finite element method to do simulation analysis about the surface accuracy and structural strength and dynamic stiffness of the mirror assembly under the force-heat coupling state. Simulation results show that the first-order natural frequency of the mirror component is 393.73Hz, and the RMS values of 1g gravity respectively reach 8.920nm, 1.856nm, 4.516nm; under 1g gravity and 4 degrees centigrade rising coupling state in three directions, the RMS values respectively reach 10.02nm, 3.312nm, 5.718nm, the results meet the design specifications requirement that the RMS value less than λ/50 (λ=632.8nm). Finally, the analysis of the random vibration was carried out on the mirror components, results show that the mirror and its supporting structure was designed reasonable which can meet the requirements of space applications.

  12. Kepler and Ground-Based Transits of the exo-Neptune HAT-P-11b

    Science.gov (United States)

    Deming, Drake; Sada, Pedro V.; Jackson, Brian; Peterson, Steven W.; Agol, Eric; Knutson, Heather A.; Jennings, Donald E.; Haase, Plynn; Bays, Kevin

    2011-01-01

    We analyze 26 archival Kepler transits of the exo-Neptune HAT-P-11b, supplemented by ground-based transits observed in the blue (B band) and near-IR (J band). Both the planet and host star are smaller than previously believed; our analysis yields Rp = 4.31 R xor 0.06 R xor and Rs = 0.683 R solar mass 0.009 R solar mass, both about 3 sigma smaller than the discovery values. Our ground-based transit data at wavelengths bracketing the Kepler bandpass serve to check the wavelength dependence of stellar limb darkening, and the J-band transit provides a precise and independent constraint on the transit duration. Both the limb darkening and transit duration from our ground-based data are consistent with the new Kepler values for the system parameters. Our smaller radius for the planet implies that its gaseous envelope can be less extensive than previously believed, being very similar to the H-He envelope of GJ 436b and Kepler-4b. HAT-P-11 is an active star, and signatures of star spot crossings are ubiquitous in the Kepler transit data. We develop and apply a methodology to correct the planetary radius for the presence of both crossed and uncrossed star spots. Star spot crossings are concentrated at phases 0.002 and +0.006. This is consistent with inferences from Rossiter-McLaughlin measurements that the planet transits nearly perpendicular to the stellar equator. We identify the dominant phases of star spot crossings with active latitudes on the star, and infer that the stellar rotational pole is inclined at about 12 deg 5 deg to the plane of the sky. We point out that precise transit measurements over long durations could in principle allow us to construct a stellar Butterfly diagram to probe the cyclic evolution of magnetic activity on this active K-dwarf star.

  13. Toward High Altitude Airship Ground-Based Boresight Calibration of Hyperspectral Pushbroom Imaging Sensors

    Directory of Open Access Journals (Sweden)

    Aiwu Zhang

    2015-12-01

    Full Text Available The complexity of the single linear hyperspectral pushbroom imaging based on a high altitude airship (HAA without a three-axis stabilized platform is much more than that based on the spaceborne and airborne. Due to the effects of air pressure, temperature and airflow, the large pitch and roll angles tend to appear frequently that create pushbroom images highly characterized with severe geometric distortions. Thus, the in-flight calibration procedure is not appropriate to apply to the single linear pushbroom sensors on HAA having no three-axis stabilized platform. In order to address this problem, a new ground-based boresight calibration method is proposed. Firstly, a coordinate’s transformation model is developed for direct georeferencing (DG of the linear imaging sensor, and then the linear error equation is derived from it by using the Taylor expansion formula. Secondly, the boresight misalignments are worked out by using iterative least squares method with few ground control points (GCPs and ground-based side-scanning experiments. The proposed method is demonstrated by three sets of experiments: (i the stability and reliability of the method is verified through simulation-based experiments; (ii the boresight calibration is performed using ground-based experiments; and (iii the validation is done by applying on the orthorectification of the real hyperspectral pushbroom images from a HAA Earth observation payload system developed by our research team—“LanTianHao”. The test results show that the proposed boresight calibration approach significantly improves the quality of georeferencing by reducing the geometric distortions caused by boresight misalignments to the minimum level.

  14. Estimation of Antarctic ozone loss from Ground-based total column measurements

    Directory of Open Access Journals (Sweden)

    J. Kuttippurath

    2010-03-01

    Full Text Available The passive ozone method is used to estimate ozone loss from ground-based measurements in the Antarctic. A sensitivity study shows that the O3 loss can be estimated within an accuracy of ~4%. The method is then applied to the observations from Amundsen-Scott/South Pole, Arrival Heights, Belgrano, Concordia, Dumont d'Urville, Faraday, Halley, Marambio, Neumayer, Rothera, Syowa and Zhongshan for the diagnosis of ozone loss in the Antarctic. On average, the five-day running mean of the vortex averaged ozone column loss deduced from the ground-based stations shows about 53% in 2009, 59% in 2008, 55% in 2007, 56% in 2006 and 61% in 2005. The observed O3 loss and loss rates are in very good agreement with the satellite observations (Ozone Monitoring Instrument and Sciamachy and are well reproduced by the model (Reprobus and SLIMCAT calculations.

    The historical ground-based total ozone measurements show that the depletion started in the late 1970s, reached a maximum in the early 1990s, stabilising afterwards at this level until present, with the exception of 2002, the year of an early vortex break-up. There is no indication of significant recovery yet.

    At southern mid-latitudes, a total ozone reduction of 40–50% is observed at the newly installed station Rio Gallegos and 25–35% at Kerguelen in October–November of 2008–2009 and 2005–2009 (except 2008 respectively, and of 10–20% at Macquarie Island in July–August of 2006–2009. This illustrates the significance of measurements at the edges of Antarctica.

  15. Comparison of OMI UV observations with ground-based measurements at high northern latitudes

    Directory of Open Access Journals (Sweden)

    G. Bernhard

    2015-03-01

    Full Text Available The Dutch-Finnish Ozone Monitoring Instrument (OMI on board NASA's Aura spacecraft provides estimates of erythemal (sunburning ultraviolet (UV dose rates and erythemal daily doses. These data were compared with ground-based measurements at 13 stations located throughout the Arctic and Scandinavia from 60 to 83° N. The study corroborates results from earlier work, but is based on a longer time series (eight vs. two years and considers additional data products, such as the erythemal dose rate at the time of the satellite overpass. Furthermore, systematic errors in satellite UV data resulting from inaccuracies in the surface albedo climatology used in the OMI UV algorithm are systematically assessed. At times when the surface albedo is correctly known, OMI data typically exceed ground-based measurements by 0–11%. When the OMI albedo climatology exceeds the actual albedo, OMI data may be biased high by as much as 55%. In turn, when the OMI albedo climatology is too low, OMI data can be biased low by up to 59%. Such large negative biases may occur when reflections from snow and ice, which increase downwelling UV irradiance, are misinterpreted as reflections from clouds, which decrease the UV flux at the surface. Results suggest that a better OMI albedo climatology would greatly improve the accuracy of OMI UV data products even if year-to-year differences of the actual albedo cannot be accounted for. A pathway for improving the OMI albedo climatology is discussed. Results also demonstrate that ground-based measurements from the center of Greenland, where high, homogenous surface albedo is observed year round, are ideally suited to detect systematic problems or temporal drifts in estimates of surface UV irradiance from space.

  16. Ground-based microwave measuring of middle atmosphere ozone and temperature profiles during sudden stratospheric warming

    Science.gov (United States)

    Feigin, A. M.; Shvetsov, A. A.; Krasilnikov, A. A.; Kulikov, M. Y.; Karashtin, D. A.; Mukhin, D.; Bolshakov, O. S.; Fedoseev, L. I.; Ryskin, V. G.; Belikovich, M. V.; Kukin, L. M.

    2012-12-01

    We carried out the experimental campaign aimed to study the response of middle atmosphere on a sudden stratospheric warming in winter 2011-2012 above Nizhny Novgorod, Russia (56N, 44E). We employed the ground-based microwave complex for remote sensing of middle atmosphere developed in the Institute of Applied Physics of the Russian Academy of Science. The complex combines two room-temperature radiometers, i.e. microwave ozonometer and the stratospheric thermometer. Ozonometer is a heterodyne spectroradiometer, operating in a range of frequencies that include the rotation transition of ozone molecules with resonance frequency 110.8 GHz. Operating frequency range of the stratospheric thermometer is 52.5-5.4 GHz and includes lower frequency edge of 5 mm molecular oxygen absorption bands and among them two relatively weak lines of O2 emission. Digital fast Fourier transform spectrometers developed by "Acqiris" are employed for signal spectral analysis. The spectrometers have frequency range 0.05-1 GHz and realizes the effective resolution about 61 KHz. For retrieval vertical profiles of ozone and temperature from radiometric data we applied novel method based on Bayesian approach to inverse problem solution, which assumed a construction of probability distribution of the characteristics of retrieved profiles with taking into account measurement noise and available a priori information about possible distributions of ozone and temperature in the middle atmosphere. Here we introduce the results of the campaign in comparison with Aura MLS data. Presented data includes one sudden stratospheric warming event which took place in January 13-14 and was accompanied by temperature increasing up to 310 K at 45 km height. During measurement period, ozone and temperature variations were (almost) anti-correlated, and total ozone abundance achieved a local maxima during the stratosphere cooling phase. In general, results of ground-based measurements are in good agreement with

  17. Ground-Based Network and Supersite Observations to Complement and Enrich EOS Research

    Science.gov (United States)

    Tsay, Si-Chee; Holben, Brent N.; Welton, Ellsworth J.

    2011-01-01

    Since 1997 NASA has been successfully launching a series of satellites - the Earth Observing System (EOS) - to intensively study, and gain a better understanding of, the Earth as an integrated system. Space-borne remote sensing observations, however, are often plagued by contamination of surface signatures. Thus, ground-based in-situ and remote-sensing measurements, where signals come directly from atmospheric constituents, the sun, and/or the Earth-atmosphere interactions, provide additional information content for comparisons that confirm quantitatively the usefulness of the integrated surface, aircraft, and satellite datasets. Through numerous participations, particularly but not limited to the EOS remote-sensing/retrieval and validation projects over the years, NASA/GSFC has developed and continuously refined ground-based networks and mobile observatories that proved to be vital in providing high temporal measurements, which complement and enrich the satellite observations. These are: the AERO NET (AErosol RObotic NETwork) a federation of ground-based globally distributed network of spectral sun-sky photometers; the MPLNET (Micro-Pulse Lidar NETwork, a similarly organized network of micro-pulse lidar systems measuring aerosol and cloud vertical structure continuously; and the SMART-COMMIT (Surface-sensing Measurements for Atmospheric Radiative Transfer - Chemical, Optical & Microphysical Measurements of In-situ Troposphere, mobile observatories, a suite of spectral radiometers and in-situ probes acquiring supersite measurements. Most MPLNET sites are collocated with those of AERONET, and both networks always support the deployment of SMART-COMMIT worldwide. These data products follow the data structure of EOS conventions: Level-0, instrument archived raw data; Level-1 (or 1.5), real-time data with no (or limited) quality assurance; Level-2, not real high temporal and spectral resolutions. In this talk, we will present NASA/GSFC groundbased facilities, serving

  18. Ground-based SMART-COMMIT Measurements for Studying Aerosol and Cloud Properties

    Science.gov (United States)

    Tsay, Si-Chee

    2008-01-01

    From radiometric principles, it is expected that the retrieved properties of extensive aerosols and clouds from reflected/emitted measurements by satellite (and/or aircraft) should be consistent with those retrieved from transmitted/emitted radiance observed at the surface. Although space-borne remote sensing observations cover large spatial domain, they are often plagued by contamination of surface signatures. Thus, ground-based in-situ and remote-sensing measurements, where signals come directly from atmospheric constituents, the sun, and/or the Earth-atmosphere interactions, provide additional information content for comparisons that confirm quantitatively the usefulness of the integrated surface, aircraft, and satellite data sets. The development and deployment of SMARTCOMMIT (Surface-sensing Measurements for Atmospheric Radiative Transfer - Chemical, Optical & Microphysical Measurements of In-situ Troposphere) mobile facilities are aimed for the optimal utilization of collocated ground-based observations as constraints to yield higher fidelity satellite retrievals and to determine any sampling bias due to target conditions. To quantify the energetics of the surface-atmosphere system and the atmospheric processes, SMART-COMMIT instruments fall into three categories: flux radiometer, radiance sensor and in-situ probe. In this paper, we will demonstrate the capability of SMART-COMMIT in recent field campaigns (e.g., CRYSTAL-FACE, UAE 2, BASEASIA, NAMMA) that were designed and executed to study the compelling variability in temporal scale of both anthropogenic and natural aerosols (e.g., biomass-burning smoke, airborne dust) and cirrus clouds. We envision robust approaches in which well-collocated ground-based measurements and space-borne observations will greatly advance our knowledge of extensive aerosols and clouds.

  19. Advanced Mirror Material System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Peregrine will bring together recent laboratory developments and mature the technology so that complete mirror and telescope assemblies can be reliably and robustly...

  20. Autism: Lost in the Mirror?

    Directory of Open Access Journals (Sweden)

    Alison Barry

    2015-01-01

    Full Text Available When I began my training as an analyst I took up a placement in an early intervention centre for autistic pre-scholars. The school was run on the psychological principles of ABA and children were tutored on a reward system promoting positive behaviors. Whilst working there I noticed that a number of children had a particular fascination for their mirrored image. This fascination was pervasive and many children would do their work primarily for the reward of the mirror. Through the lens of psychoanalysis I found this very interesting and Lacan’s Mirror Phase immediately came to mind and with this it bore the question as to whether or not there was something in the Mirror Phase of development that had an impact on what we see as symptoms of Autism.

  1. Fast Picometer Mirror Mount Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is a 6DOF controllable mirror mount with high dynamic range and fast tip/tilt capability for space based applications. It will enable the...

  2. Reflections on a Black Mirror

    CERN Document Server

    Good, Michael R R

    2016-01-01

    A black mirror is an accelerated boundary that produces particles in an exact correspondence to an evaporating black hole. We investigate the spectral dynamics of the particle creation during the formation process.

  3. Dielectric Coatings for IACT Mirrors

    CERN Document Server

    Förster, A; Chadwick, P; Held, M

    2013-01-01

    Imaging Atmospheric Cherenkov Telescopes for very-high energy gamma-ray astronomy need mirror with high reflectance roughly in the wavelength between 300 and 550 nm. The current standard reflective layer of such mirrors is aluminum. Being permanently exposed to the environment they show a constant degradation over the years. New and improved dielectric coatings have been developed to enhance their resistance to environmental impact and to extend their possible lifetime. In addition, these customized coatings have an increased reflectance of over 95% and are designed to significantly lower the night-sky background contribution. The development of such coatings for mirrors with areas up to 2 m2 and low application temperatures to suite the composite materials used for the new mirror susbtrates of the Cherenkov Telescope Array (CTA) and the results of extensive durability tests are presented.

  4. Ground-based measurements of aerosol optical properties and radiative forcing in North China

    Institute of Scientific and Technical Information of China (English)

    Hongbin Chen; Xiangao Xia; Pucai Wang; Wenxing Zhang

    2007-01-01

    In order to gain an insight into the aerosol properties and their climatic effect over the continental source regions of China, it is of significance to carry out long-term ground-based measurements of aerosol optical properties and radiative forcing. A couple of temporary and permanent Aerosol Robotic Network (AERONET) sites and three comprehensive radiative sites were established in China as a result of international cooperation in recent years. Heavy aerosol loading and significant temporal and spatial variation over North China are revealed by the AERONET data.Aerosol-induced reductions in surface radiation budget are examined on the basis of collocated observations by sun photometers and pyranometers.

  5. Estimation of above ground biomass in boreal forest using ground-based Lidar

    Science.gov (United States)

    Taheriazad, L.; Moghadas, H.; Sanchez-Azofeifa, A.

    2017-05-01

    Assessing above ground biomass of forest is important for carbon storage monitoring in boreal forest. In this study, a new model is developed to estimate the above ground biomass using ground based Lidar data. 21 trees were measured and scanned across the plot area study in boreal forests of Alberta, Canada. The study area was scanned in the summer season 2014 to quantify the green biomass. The average of total crown biomass and green biomass in this study was 377 kg (standard deviation, S.D. = 243 kg) and 6.42 kg (S.D. = 2.69 m), respectively.

  6. Synergetic ground-based methods for remote measurements of ozone vertical profiles

    Science.gov (United States)

    Timofeyev, Yuriy; Kostsov, Vladimir; Virolainen, Yana

    2013-05-01

    The technique of combining ground-based measurements in infrared and microwave spectral regions in order to achieve higher accuracy of ozone profile retrieval in extensive altitude ranges is described and analyzed. The information content, errors, altitude ranges and vertical resolution of ozone profile retrieval have been studied on the basis of numerical simulation of synergetic experiments. Optimal conditions of measurements are defined and requirements to additional information are formulated. The first results on ozone vertical profile retrieval using groundbased measurements of FTIR-spectrometer and microwave radiometer are given.

  7. Solar diameter, eclipses and transits: the importance of ground-based observations

    CERN Document Server

    Sigismondi, Costantino

    2012-01-01

    According to satellite measurements the difference between polar and equatorial radius does not exceed 10 milliarcsec. These measurements are differential, and the absolute value of the solar diameter is not precisely known to a level of accuracy needed for finding variations during years or decades. Moreover the lifetime of a satellite is limited, and its calibration is not stable. This shows the need to continue ground-based observations of the Sun exploiting in particular the methods less affected by atmospheric turbulence, as the planetary transits and the total and annular eclipses. The state of art, the advantages and the limits of these two methods are here considered.

  8. Asteroseismology of Solar-type stars with Kepler III. Ground-based Data

    CERN Document Server

    Molenda-Zakowicz, Joanna; Sousa, Sergio; Frasca, Antonio; Biazzo, Katia; Huber, Daniel; Ireland, Mike; Bedding, Tim; Stello, Dennis; Uytterhoeven, Katrien; Dreizler, Stefan; De Cat, Peter; Briquet, Maryline; Catanzaro, Giovanni; Karoff, Chistoffer; Frandsen, Soeren; Spezzi, Loredana; Catala, Claude

    2010-01-01

    We report on the ground-based follow-up program of spectroscopic and photometric observations of solar-like asteroseismic targets for the Kepler space mission. These stars constitute a large group of more than thousand objects which are the subject of an intensive study of the Kepler Asteroseismic Science Consortium Working Group 1 (KASC WG-1). The main goal of this coordinated research is the determination of the fundamental stellar atmospheric parameters, which are used for the computing of their asteroseismic models, as well as for the verification of the Kepler Input Catalogue (KIC).

  9. Boost-Phase ballistic missile trajectory estimation with ground based radar

    Institute of Scientific and Technical Information of China (English)

    Tang Yuyan; Huang Peikang

    2006-01-01

    A conditional boost-phase trajectory estimation method based on ballistic missile (BM) information database and classification is developed to estimate and predict boos-phase BM trajectory. The main uncertain factors to describe BM dynamics equation are reduced to the control law of trajectory pitch angle in boost-phase. After the BM mass at the beginning of estimation, the BM attack angle and the modification of engine thrust denoting BM acceleration are modeled reasonably, the boost-phase BM trajectory estimation with ground based radar is well realized. The validity of this estimation method is testified by computer simulation with a typical example.

  10. Integrated interpretation of helicopter and ground-based geophysical data recorded within the Okavango Delta, Botswana

    DEFF Research Database (Denmark)

    Podgorski, Joel E.; Green, Alan G.; Kalscheuer, Thomas

    2015-01-01

    ) data recorded across most of the delta, (ii) 2D models and images derived from ground-based electrical resistance tomographic, transient electromagnetic, and high resolution seismic reflection/refraction tomographic data acquired at four selected sites in western and north-central regions of the delta...... resistivities and very low to low P-wave velocities. Except for images of several buried abandoned river channels, it is non-reflective. The laterally extensive underlying unit of low resistivities, low P-wave velocity, and subhorizontal reflectors very likely contains saline-water-saturated sands and clays...... reflectivity. The interface between the POM unit and basement is a prominent seismic reflector....

  11. Hypergravity Facilities in the ESA Ground-Based Facility Program - Current Research Activities and Future Tasks

    Science.gov (United States)

    Frett, Timo; Petrat, Guido; W. A. van Loon, Jack J.; Hemmersbach, Ruth; Anken, Ralf

    2016-06-01

    Research on Artificial Gravity (AG) created by linear acceleration or centrifugation has a long history and could significantly contribute to realize long-term human spaceflight in the future. Employing centrifuges plays a prominent role in human physiology and gravitational biology. This article gives a short review about the background of Artificial Gravity with respect to hypergravity (including partial gravity) and provides information about actual ESA ground-based facilities for research on a variety of biosystems such as cells, plants, animals or, particularly, humans.

  12. Images of Neptune's ring arcs obtained by a ground-based telescope

    Science.gov (United States)

    Sicardy, B.; Roddier, F.; Roddier, C.; Perozzi, E.; Graves, J. E.; Guyon, O.; Northcott, M. J.

    1999-08-01

    Neptune has a collection of incomplete narrow rings, known as ring arcs, which should in isolation be destroyed by differential motion in a matter of months. Yet since first discovered by stellar occultations in 1984, they appear to have persisted, perhaps through a gravitational resonance effect involving the satellite Galatea. Here we report ground-based observations of the ring arcs, obtained using an adaptive optics system. Our data, and those obtained using the Hubble Space Telescope (reported in a companion paper), indicate that the ring arcs are near, but not within the resonance with Galatea, in contrast to what is predicted by some models.

  13. SCENARIO AND TARGET SIMULATION FOR A GROUND BASED MULTIFUNCTION PHASED ARRAY RADAR

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper describes a scenario and target simulation which operates in non real-time to provide full closed-loop operation of the ground based multifunction phased array radar simulation system in support of ballistic missile defence experiments against countermeasure.By simulating the target scattering signature and dynamical signature,this scenario and target simulation provide re- alistic scenario source to evaluate the system performance of multifunction phased array radar,and the key algorithms verification and validation such as target tracking,multi-target imaging and target recognition.

  14. The laser calibration system for the STACEE ground-based gamma ray detector

    CERN Document Server

    Hanna, D

    2002-01-01

    We describe the design and performance of the laser system used for calibration monitoring of components of the STACEE detector. STACEE is a ground based gamma ray detector which uses the heliostats of a solar power facility to collect and focus Cherenkov light onto a system of secondary optics and photomultiplier tubes. To monitor the gain and check the linearity and timing properties of the phototubes and associated electronics, a system based on a dye laser, neutral density filters and optical fibres has been developed. In this paper we describe the system and present some results from initial tests made with it.

  15. Ground-Based Gas-Liquid Flow Research in Microgravity Conditions: State of Knowledge

    Science.gov (United States)

    McQuillen, J.; Colin, C.; Fabre, J.

    1999-01-01

    During the last decade, ground-based microgravity facilities have been utilized in order to obtain predictions for spacecraft system designers and further the fundamental understanding of two-phase flow. Although flow regime, pressure drop and heat transfer coefficient data has been obtained for straight tubes and a limited number of fittings, measurements of the void fraction, film thickness, wall shear stress, local velocity and void information are also required in order to develop general mechanistic models that can be utilized to ascertain the effects of fluid properties, tube geometry and acceleration levels. A review of this research is presented and includes both empirical data and mechanistic models of the flow behavior.

  16. Ground-based and spaceborn observations of the type II burst with developed fine structure

    Science.gov (United States)

    Dorovskyy, V.; Melnik, V.; Konovalenko, A.; Brazhenko, A.; Rucker, H.; Stanislavskyy, A.; Panchenko, M.

    2012-09-01

    The combination of two huge ground-based radio telescopes (UTR-2 and URAN-2) operated in decameter wavelengths with three spatially separated spacecrafts (SOHO, STEREO-A and STEREO-B) equipped with white light coronagraphs, UV telescopes and decameter-hectometer band radio telescopes created a unique opportunity to investigate the high energy solar transients, such as CMEs and their manifestations in radio bands - type II bursts. In this paper we made detailed analysis of the powerful and complex event occurred on 7 June 2011 consisted of Halo-CME and type II burst with rich fine structure.

  17. Advanced ground-based gravitational-wave detectors' potential to detect generic deviations from general relativity

    CERN Document Server

    Narikawa, Tatsuya

    2016-01-01

    We discuss the potential of the advanced ground-based gravitational-wave detectors, such as LIGO, Virgo, and KAGRA, to detect generic deviations of gravitational waveforms from the prediction of General Relativity. We use the parameterized post-Einsteinian formalism to characterize the deviations, and assess how much magnitude of the deviations are detectable by using an approximate decision scheme based on Bayesian statistics. We find that there exist detectable regions of the parameterized post-Einsteinian parameters by using a single gravitational wave event. The regions are not excluded by currently existing binary pulsar observations for the parameterized post-Einsteinian parameters at higher post-Newtonian order.

  18. Polymer glazing for silver mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Neidlinger, H H; Schissel, P

    1985-07-01

    This paper reports on an evaluation and modification of polymeric glazings to protect silver mirrors. The mirrors were made using Corning 7809 glass as a substrate onto which a thin silver film is deposited. The modified polymeric films are then cast from solution onto the silver. The mirrors were characterized by measuring the hemispherical reflectance and the specular reflectance at 660 nm and selected acceptance angles (7.5 mrad or 3.5 mrad). The mirrors were exposed to environmental degradation using accelerated weathering devices and outdoor exposure. Empirical evidence has demonstrated that polymethylmethacrylate is a stable polymer in a terrestrial environment, but the polymer does not provide adequate protection for the silver reflector. The crucial role in degradation played by ultraviolet (uv) light is shown by several experimental results. It has been demonstrated that uv stabilizers added to the polymer improve the weatherability of mirrors. The relative effectiveness of different stabilizers will be discussed in terms of the weathering modes, retention of optical properties, and effectiveness of the additives. The process for silver deposition influences the reflectance of silver mirrors, and the optical properties depend on subtle relationships between the metallization and the dielectric (polymeric) films that are in contact with the silver.

  19. Study on the Application Technology of Ground-based InSAR%地基雷达干涉技术应用研究进展

    Institute of Scientific and Technical Information of China (English)

    邱志伟; 汪学琴; 岳顺; 郭献涛; 桑杰

    2015-01-01

    近年来,地基合成孔径雷达干涉技术的应用领域不断地扩展.本文详细地介绍了变形监测系统IBIS,并对其监测原理进行了简单概括.不仅对地基InSAR技术近期的应用及发展进行归纳总结,而且对该技术存在的问题从大气改正、断点校正及数据融合等方面进行深入的分析和讨论.通过对地基雷达干涉技术的应用研究分析,说明其在变形监测中将具有更为广泛的应用前景.%In recent years, the application field of ground-based synthetic aperture radar interferometry technique has been expanded. This paper introduces the deformation monitoring system IBIS and summarized the principle of monitoring briefly. Not only the application and development of InSAR technology are summarized in this paper, and the existing problems such as the atmospheric correction, breakpoint adjustment and the data fusion are analyzed and discussed in depth. Through the application research of ground radar interferometry analysis, this technology has broad application prospects in deformation monitoring.

  20. Detection of atmospheric Cherenkov radiation using solar heliostat mirrors

    Science.gov (United States)

    Ong, R. A.; Bhattacharya, D.; Covault, C. E.; Dixon, D. D.; Gregorich, D. T.; Hanna, D. S.; Oser, S.; Québert, J.; Smith, D. A.; Tümer, O. T.; Zych, A. D.

    1996-10-01

    There is considerable interest world-wide in developing large area atmospheric Cherenkov detectors for ground-based gamma-ray astronomy. This interest stems, in large part, from the fact that the gamma-ray energy region between 20 and 250 GeV is unexplored by any experiment. Atmospheric Cherenkov detectors offer a possible way to explore this region, but large photon collection areas are needed to achieve low energy thresholds. We are developing an experiment using the heliostat mirrors of a solar power plant as the primary collecting element. As part of this development, we built a detector using four heliostat mirrors, a secondary Fresnel lens, and a fast photon detection system. In November 1994, we used this detector to record atmospheric Cherenkov radiation produced by cosmic ray particles showering in the atmosphere. The detected rate of cosmic ray events was consistent with an energy threshold near 1 TeV. The data presented here represent the first detection of atmospheric Cherenkov radiation using solar heliostats viewed from a central tower.

  1. Exploring the relationship between monitored ground-based and satellite aerosol measurements over the City of Johannesburg

    CSIR Research Space (South Africa)

    Garland, Rebecca M

    2012-09-01

    Full Text Available This project studied the relationship between aerosol optical depth (AOD) from the Multi-angle Imaging SpectroRadiometer (MISR) instrument on the Terra satellite, and ground-based monitored particulate matter (PM) mass concentrations measured...

  2. A Process Model for Deployment Planning of Ground-based Air Defense System Against Asymmetric Homeland Threat

    Science.gov (United States)

    2009-01-01

    A Process Model for Deployment Planning of Ground-based Air Defense System Against Asymmetric Homeland Threat Ronald L. Cypert Scientific...units, along with coordination at the state and federal agency level, a dynamic process modeling capability was chosen to chart the myriad...COVERED 00-00-2009 to 00-00-2009 4. TITLE AND SUBTITLE A Process Model for Deployment Planning of Ground-based Air Defense System Against

  3. Alignment Mirror Mechanisms for Space Use

    Science.gov (United States)

    Jau, Bruno M.; McKinney, Colin M.; Smythe, Robert F.; Palmer, Dean

    2011-01-01

    The paper describes an optical Alignment Mirror Mechanism (AMM), and discusses its control scheme. The mirror's angular positioning accuracy requirement is +/- 0.2 arc-sec. This requires the mirror's linear positioning actuators to have a positioning accuracy of +/- 109 nm to enable the mirror to meet the angular tip/tilt accuracy requirement. Demonstrated capabilities are +/- 35 nm linear positioning capability at the actuator, which translates into +/- 0.07 arc-sec angular mirror positioning accuracy.

  4. Development of a Ground-Based Atmospheric Monitoring Network for the Global Mercury Observation System (GMOS

    Directory of Open Access Journals (Sweden)

    Sprovieri F.

    2013-04-01

    Full Text Available Consistent, high-quality measurements of atmospheric mercury (Hg are necessary in order to better understand Hg emissions, transport, and deposition on a global scale. Although the number of atmospheric Hg monitoring stations has increased in recent years, the available measurement database is limited and there are many regions of the world where measurements have not been extensively performed. Long-term atmospheric Hg monitoring and additional ground-based monitoring sites are needed in order to generate datasets that will offer new insight and information about the global scale trends of atmospheric Hg emissions and deposition. In the framework of the Global Mercury Observation System (GMOS project, a coordinated global observational network for atmospheric Hg is being established. The overall research strategy of GMOS is to develop a state-of-the-art observation system able to provide information on the concentration of Hg species in ambient air and precipitation on the global scale. This network is being developed by integrating previously established ground-based atmospheric Hg monitoring stations with newly established GMOS sites that are located both at high altitude and sea level locations, as well as in climatically diverse regions. Through the collection of consistent, high-quality atmospheric Hg measurement data, we seek to create a comprehensive assessment of atmospheric Hg concentrations and their dependence on meteorology, long-range atmospheric transport and atmospheric emissions.

  5. Potential use of ground-based sensor technologies for weed detection.

    Science.gov (United States)

    Peteinatos, Gerassimos G; Weis, Martin; Andújar, Dionisio; Rueda Ayala, Victor; Gerhards, Roland

    2014-02-01

    Site-specific weed management is the part of precision agriculture (PA) that tries to effectively control weed infestations with the least economical and environmental burdens. This can be achieved with the aid of ground-based or near-range sensors in combination with decision rules and precise application technologies. Near-range sensor technologies, developed for mounting on a vehicle, have been emerging for PA applications during the last three decades. These technologies focus on identifying plants and measuring their physiological status with the aid of their spectral and morphological characteristics. Cameras, spectrometers, fluorometers and distance sensors are the most prominent sensors for PA applications. The objective of this article is to describe-ground based sensors that have the potential to be used for weed detection and measurement of weed infestation level. An overview of current sensor systems is presented, describing their concepts, results that have been achieved, already utilized commercial systems and problems that persist. A perspective for the development of these sensors is given. © 2013 Society of Chemical Industry.

  6. Ground-based observation of emission lines from the corona of a red-dwarf star.

    Science.gov (United States)

    Schmitt, J H; Wichmann, R

    2001-08-02

    All 'solar-like' stars are surrounded by coronae, which contain magnetically confined plasma at temperatures above 106 K. (Until now, only the Sun's corona could be observed in the optical-as a shimmering envelope during a total solar eclipse.) As the underlying stellar 'surfaces'-the photospheres-are much cooler, some non-radiative process must be responsible for heating the coronae. The heating mechanism is generally thought to be magnetic in origin, but is not yet understood even for the case of the Sun. Ultraviolet emission lines first led to the discovery of the enormous temperature of the Sun's corona, but thermal emission from the coronae of other stars has hitherto been detectable only from space, at X-ray wavelengths. Here we report the detection of emission from highly ionized iron (Fe XIII at 3,388.1 A) in the corona of the red-dwarf star CN Leonis, using a ground-based telescope. The X-ray flux inferred from our data is consistent with previously measured X-ray fluxes, and the non-thermal line width of 18.4 km s-1 indicates great similarities between solar and stellar coronal heating mechanisms. The accessibility and spectral resolution (45,000) of the ground-based instrument are much better than those of X-ray satellites, so a new window to the study of stellar coronae has been opened.

  7. Proceedings of the 2011 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Wetovsky, Marvin A. [Editor; Patterson, Eileen F. [Editor; Sandoval, Marisa N. [Editor

    2011-09-13

    These proceedings contain papers prepared for the Monitoring Research Review 2011: Ground-Based Nuclear Explosion Monitoring Technologies, held 13-15 September, 2011 in Tucson, Arizona. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Defense Threat Reduction Agency (DTRA), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), National Science Foundation (NSF), and other invited sponsors. The scientific objectives of the research are to improve the United States' capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.

  8. Ground-based Observations of the Solar Sources of Space Weather (Invited Review)

    CERN Document Server

    Veronig, Astrid M

    2016-01-01

    Monitoring of the Sun and its activity is a task of growing importance in the frame of space weather research and awareness. Major space weather disturbances at Earth have their origin in energetic outbursts from the Sun: solar flares, coronal mass ejections and associated solar energetic particles. In this review we discuss the importance and complementarity of ground-based and space-based observations for space weather studies. The main focus is drawn on ground-based observations in the visible range of the spectrum, in particular in the diagnostically manifold H$\\alpha$ spectral line, which enables us to detect and study solar flares, filaments, filament eruptions, and Moreton waves. Existing H$\\alpha$ networks such as the GONG and the Global High-Resolution H$\\alpha$ Network are discussed. As an example of solar observations from space weather research to operations, we present the system of real-time detection of H$\\alpha$ flares and filaments established at Kanzelh\\"ohe Observatory (KSO; Austria) in the...

  9. Proceedings of the 27th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Wetovsky, Marvin A. [Editor; Benson, Jody [Editor; Patterson, Eileen F. [Editor

    2005-09-20

    These proceedings contain papers prepared for the 27th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 20-22 September, 2005 in Rancho Mirage, California. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.

  10. Modelling systematics of ground-based transit photometry I. Implications on transit timing variations

    CERN Document Server

    von Essen, C; Mallonn, M; Tingley, B; Marcussen, M

    2016-01-01

    The transit timing variation technique (TTV) has been widely used to detect and characterize multiple planetary systems. Due to the observational biases imposed mainly by the photometric conditions and instrumentation and the high signal-to-noise required to produce primary transit observations, ground-based data acquired using small telescopes limit the technique to the follow-up of hot Jupiters. However, space-based missions such as Kepler and CoRoT have already revealed that hot Jupiters are mainly found in single systems. Thus, it is natural to question ourselves if we are properly using the observing time at hand carrying out such follow-ups, or if the use of medium-to-low quality transit light curves, combined with current standard techniques of data analysis, could be playing a main role against exoplanetary search via TTVs. The purpose of this work is to investigate to what extent ground-based observations treated with current modelling techniques are reliable to detect and characterize additional pla...

  11. Pc5 Oscillation Analysis by the Satellite and Ground-Based Data

    Institute of Scientific and Technical Information of China (English)

    A. Potapov; T. Polyushkina; T. L. Zhang; H. Zhao; A. Guglielmi; J. Kultima

    2005-01-01

    Large amplitude Pc5 event was observed in the space and on ground on August 3, 2001, about three hours after contact of the strong discontinuity in the solar wind with the magnetosphere according to data from ACE and Wind satellites. The Pc5 amplitude was as high as 15 nT in the tail of magnetosphere and about 5 nT at the ground based stations. In the magnetosphere Pc5 waves were observed by Cluster and Polar satellites, which occupied positions in the morning part of the near tail at the close field lines but were parted by distance of 11.5 Re, mainly along the x-axis of the GSM coordinate system. Both compressional and transverse components of the Pc5 wave activity were observed in the space, with the transverse component having the larger amplitude. Time delay between the Cluster and Polar satellites was about 8 minutes, which could be interpreted as a wave propagation from the geomagnetic tail to the Earth with the 150km/s group velocity.The ground-based Pc5 activity was analysed by using data from the Image magnetometer network. Doubtless demonstrations of a field line resonant structure were found in variations of amplitude and polarization with latitude. Finnish chain of search coil magnetometers observed modulated Pc1 emission simultaneously with the Pc5 wave train. A possibility of non-linear impact of Pc5 wave energy on the plasma and waves in the magnetosphere is discussed.

  12. CRRES/Ground-based multi-instrument observations of an interval of substorm activity

    Directory of Open Access Journals (Sweden)

    T. K. Yeoman

    Full Text Available Observations are presented of data taken during a 3-h interval in which five clear substorm onsets/intensifications took place. During this interval ground-based data from the EISCAT incoherent scatter radar, a digital CCD all sky camera, and an extensive array of magnetometers were recorded. In addition data from the CRRES and DMSP spacecraft, whose footprints passed over Scandinavia very close to most of the ground-based instrumentation, are available. The locations and movements of the substorm current system in latitude and longitude, determined from ground and spacecraft magnetic field data, have been correlated with the locations and propagation of increased particle precipitation in the E-region at EISCAT, increased particle fluxes measured by CRRES and DMSP, with auroral luminosity and with ionospheric convection velocities. The onsets and propagation of the injection of magnetospheric particle populations and auroral luminosity have been compared. CRRES was within or very close to the substorm expansion phase onset sector during the interval. The onset region was observed at low latitudes on the ground, and has been confirmed to map back to within L=7 in the magnetotail. The active region was then observed to propagate tailward and poleward. Delays between the magnetic signature of the substorm field aligned currents and field dipolarisation have been measured. The observations support a near-Earth plasma instability mechanism for substorm expansion phase onset.

  13. Towards the development of tamper-resistant, ground-based mobile sensor nodes

    Science.gov (United States)

    Mascarenas, David; Stull, Christopher; Farrar, Charles

    2011-11-01

    Mobile sensor nodes hold great potential for collecting field data using fewer resources than human operators would require and potentially requiring fewer sensors than a fixed-position sensor array. It would be very beneficial to allow these mobile sensor nodes to operate unattended with a minimum of human intervention. In order to allow mobile sensor nodes to operate unattended in a field environment, it is imperative that they be capable of identifying and responding to external agents that may attempt to tamper with, damage or steal the mobile sensor nodes, while still performing their data collection mission. Potentially hostile external agents could include animals, other mobile sensor nodes, or humans. This work will focus on developing control policies to help enable a mobile sensor node to identify and avoid capture by a hostile un-mounted human. The work is developed in a simulation environment, and demonstrated using a non-holonomic, ground-based mobile sensor node. This work will be a preliminary step toward ensuring the cyber-physical security of ground-based mobile sensor nodes that operate unattended in potentially unfriendly environments.

  14. a Universal De-Noising Algorithm for Ground-Based LIDAR Signal

    Science.gov (United States)

    Ma, Xin; Xiang, Chengzhi; Gong, Wei

    2016-06-01

    Ground-based lidar, working as an effective remote sensing tool, plays an irreplaceable role in the study of atmosphere, since it has the ability to provide the atmospheric vertical profile. However, the appearance of noise in a lidar signal is unavoidable, which leads to difficulties and complexities when searching for more information. Every de-noising method has its own characteristic but with a certain limitation, since the lidar signal will vary with the atmosphere changes. In this paper, a universal de-noising algorithm is proposed to enhance the SNR of a ground-based lidar signal, which is based on signal segmentation and reconstruction. The signal segmentation serving as the keystone of the algorithm, segments the lidar signal into three different parts, which are processed by different de-noising method according to their own characteristics. The signal reconstruction is a relatively simple procedure that is to splice the signal sections end to end. Finally, a series of simulation signal tests and real dual field-of-view lidar signal shows the feasibility of the universal de-noising algorithm.

  15. Understanding the Laminar Distribution of Tropospheric Ozone from Ground-Based, Airborne, Spaceborne, and Modeling Perspectives

    Science.gov (United States)

    Newchurch, Mike; Johnson, Matthew S.; Huang, Guanyu; Kuang, Shi; Wang, Lihua; Chance, Kelly; Liu, Xiong

    2016-01-01

    Laminar ozone structure is a ubiquitous feature of tropospheric-ozone distributions resulting from dynamic and chemical atmospheric processes. Understanding the characteristics of these ozone laminae and the mechanisms responsible for producing them is important to outline the transport pathways of trace gases and to quantify the impact of different sources on tropospheric background ozone. In this study, we present a new method to detect ozone laminae to understand their climatological characteristics of occurrence frequency in terms of thickness and altitude. We employ both ground-based and airborne ozone lidar measurements and other synergistic observations and modeling to investigate the sources and mechanisms such as biomass burning transport, stratospheric intrusion, lightning-generated NOx, and nocturnal low-level jets that are responsible for depleted or enhanced tropospheric ozone layers. Spaceborne (e.g., OMI (Ozone Monitoring Instrument), TROPOMI (Tropospheric Monitoring Instrument), TEMPO (Tropospheric Emissions: Monitoring of Pollution)) measurements of these laminae will observe greater horizontal extent and lower vertical resolution than balloon-borne or lidar measurements will quantify. Using integrated ground-based, airborne, and spaceborne observations in a modeling framework affords insight into how to gain knowledge of both the vertical and horizontal evolution of these ubiquitous ozone laminae.

  16. Ground Based Retrievals of Small Ice Crystals and Water Phase in Arctic Cirrus

    Science.gov (United States)

    Mishra, Subhashree; Mitchell, David L.; DeSlover, Daniel

    2009-03-01

    The microphysical properties of cirrus clouds are uncertain due to the problem of ice particles shattering at the probe inlet upon sampling. To facilitate better estimation of small ice crystal concentrations in cirrus clouds, a new ground-based remote sensing technique has been used in combination with in situ aircraft measurements. Data from the Mixed-Phase Arctic Cloud Experiment (M-PACE), conducted at the north slope of Alaska (winter 2004), have been used to test a new method for retrieving the liquid water path (LWP) and ice water path (IWP) in mixed phase clouds. The framework of the retrieval algorithm consists of the modified anomalous diffraction approximation or MADA (for mixed phase cloud optical properties), a radar reflectivity-ice microphysics relationship and a temperature-dependent ice particle size distribution (PSD) scheme. Cloud thermal emission measurements made by the ground-based Atmospheric Emitted Radiance Interferometer (AERI) yield information on the total water path (TWP) while reflectivity measurements from the Millimeter Cloud Radar (MMCR) are used to derive the IWP. The AERI is also used to indicate the concentration of small ice crystals (DBeer's law absorption. While this is still a work in progress, the anticipated products from this AERI-radar retrieval scheme are the IWP, LWP, small-to-large ice crystal number concentration ratio and effective diameter for cirrus, as well as the ice particle number concentration for a given ice water content (IWC).

  17. Synchronized observations by using the STEREO and the largest ground-based decametre radio telescope

    Science.gov (United States)

    Konovalenko, A. A.; Stanislavsky, A. A.; Rucker, H. O.; Lecacheux, A.; Mann, G.; Bougeret, J.-L.; Kaiser, M. L.; Briand, C.; Zarka, P.; Abranin, E. P.; Dorovsky, V. V.; Koval, A. A.; Mel'nik, V. N.; Mukha, D. V.; Panchenko, M.

    2013-08-01

    We consider the approach to simultaneous (synchronous) solar observations of radio emission by using the STEREO-WAVES instruments (frequency range 0.125-16 MHz) and the largest ground-based low-frequency radio telescope. We illustrate it by the UTR-2 radio telescope implementation (10-30 MHz). The antenna system of the radio telescope is a T-shape-like array of broadband dipoles and is located near the village Grakovo in the Kharkiv region (Ukraine). The third observation point on the ground in addition to two space-based ones improves the space-mission performance capabilities for the determination of radio-emission source directivity. The observational results from the high sensitivity antenna UTR-2 are particularly useful for analysis of STEREO data in the condition of weak event appearances during solar activity minima. In order to improve the accuracy of flux density measurements, we also provide simultaneous observations with a large part of the UTR-2 radio telescope array and its single dipole close to the STEREO-WAVES antennas in sensitivity. This concept has been studied by comparing the STEREO data with ground-based records from 2007-2011 and shown to be effective. The capabilities will be useful in the implementation of new instruments (LOFAR, LWA, MWA, etc.) and during the future Solar Orbiter mission.

  18. Ground-based and spacecraft observations of lightning activity on Saturn

    Science.gov (United States)

    Zakharenko, V.; Mylostna, C.; Konovalenko, A.; Zarka, P.; Fischer, G.; Grießmeier, J.-M.; Litvinenko, G.; Rucker, H.; Sidorchuk, M.; Ryabov, B.; Vavriv, D.; Ryabov, V.; Cecconi, B.; Coffre, A.; Denis, L.; Fabrice, C.; Pallier, L.; Schneider, J.; Kozhyn, R.; Vinogradov, V.; Mukha, D.; Weber, R.; Shevchenko, V.; Nikolaenko, V.

    2012-02-01

    In late 2007, Saturn electrostatic discharges (SED) were simultaneously observed at the radio telescope UTR-2 and with the Cassini spacecraft. Observations at UTR-2 were performed with a multichannel receiver in the frequency range 12-33 MHz, and those performed on Cassini-with a swept frequency receiver that is part of the RPWS (Radio and Plasma Wave Science) instrument in the frequency band 1.8-16 MHz. We got a very good coincidence between data of UTR-2 and Cassini. It is shown for the first time that ground-based radio astronomy lets us detect Saturn's lightning with a high degree of reliability despite terrestrial interferences. This is the necessary basis for further detailed study of the temporal and spectral characteristics of the SEDs with ground based radio telescopes. Based on six observation sessions, several parameters of SEDs were determined, in particularly a correlation of 0.77±0.15 between the average intensity of storms and the e-folding time.

  19. Nighttime Aerosol Optical Depth Measurements Using a Ground-based Lunar Photometer

    Science.gov (United States)

    Berkoff, Tim; Omar, Ali; Haggard, Charles; Pippin, Margaret; Tasaddaq, Aasam; Stone, Tom; Rodriguez, Jon; Slutsker, Ilya; Eck, Tom; Holben, Brent; hide

    2015-01-01

    In recent years it was proposed to combine AERONET network photometer capabilities with a high precision lunar model used for satellite calibration to retrieve columnar nighttime AODs. The USGS lunar model can continuously provide pre-atmosphere high precision lunar irradiance determinations for multiple wavelengths at ground sensor locations. When combined with measured irradiances from a ground-based AERONET photometer, atmospheric column transmissions can determined yielding nighttime column aerosol AOD and Angstrom coefficients. Additional demonstrations have utilized this approach to further develop calibration methods and to obtain data in polar regions where extended periods of darkness occur. This new capability enables more complete studies of the diurnal behavior of aerosols, and feedback for models and satellite retrievals for the nighttime behavior of aerosols. It is anticipated that the nighttime capability of these sensors will be useful for comparisons with satellite lidars such as CALIOP and CATS in additional to ground-based lidars in MPLNET at night, when the signal-to-noise ratio is higher than daytime and more precise AOD comparisons can be made.

  20. Evaluation of brightness temperature from a forward model of ground-based microwave radiometer

    Indian Academy of Sciences (India)

    S Rambabu; J S Pillai; A Agarwal; G Pandithurai

    2014-06-01

    Ground-based microwave radiometers are getting great attention in recent years due to their capability to profile the temperature and humidity at high temporal and vertical resolution in the lower troposphere. The process of retrieving these parameters from the measurements of radiometric brightness temperature () includes the inversion algorithm, which uses the background information from a forward model. In the present study, an algorithm development and evaluation of this forward model for a ground-based microwave radiometer, being developed by Society for Applied Microwave Electronics Engineering and Research (SAMEER) of India, is presented. Initially, the analysis of absorption coefficient and weighting function at different frequencies was made to select the channels. Further the range of variation of for these selected channels for the year 2011, over the two stations Mumbai and Delhi is discussed. Finally the comparison between forward-model simulated s and radiometer measured s at Mahabaleshwar (73.66°E and 17.93°N) is done to evaluate the model. There is good agreement between model simulations and radiometer observations, which suggests that these forward model simulations can be used as background for inversion models for retrieving the temperature and humidity profiles.

  1. Proceedings of the 29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Wetovsky, Marvin A. [Editor; Benson, Jody [Editor; Patterson, Eileen F. [Editor

    2007-09-25

    These proceedings contain papers prepared for the 29th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 25-27 September, 2007 in Denver, Colorado. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.

  2. Proceedings of the 28th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Wetovsky, Marvin A. [Editor; Benson, Jody [Editor; Patterson, Eileen F. [Editor

    2006-09-19

    These proceedings contain papers prepared for the 28th Seismic Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 19-21 September, 2006 in Orlando, Florida. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.

  3. Proceedings of the 30th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Wetovsky, Marv A [Los Alamos National Laboratory; Aguilar-chang, Julio [Los Alamos National Laboratory; Arrowsmith, Marie [Los Alamos National Laboratory; Arrowsmith, Stephen [Los Alamos National Laboratory; Baker, Diane [Los Alamos National Laboratory; Begnaud, Michael [Los Alamos National Laboratory; Harste, Hans [Los Alamos National Laboratory; Maceira, Monica [Los Alamos National Laboratory; Patton, Howard [Los Alamos National Laboratory; Phillips, Scott [Los Alamos National Laboratory; Randall, George [Los Alamos National Laboratory; Revelle, Douglas [Los Alamos National Laboratory; Rowe, Charlotte [Los Alamos National Laboratory; Stead, Richard [Los Alamos National Laboratory; Steck, Lee [Los Alamos National Laboratory; Whitaker, Rod [Los Alamos National Laboratory; Yang, Xiaoning [Los Alamos National Laboratory

    2008-09-23

    These proceedings contain papers prepared for the 30th Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies, held 23-25 September, 2008 in Portsmouth, Virginia. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Technical Applications Center (AFTAC), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States’ capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.

  4. Proceedings of the 2010 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Wetovsky, Marvin A [Editor; Patterson, Eileen F [Editor

    2010-09-21

    These proceedings contain papers prepared for the Monitoring Research Review 2010: Ground-Based Nuclear Explosion Monitoring Technologies, held 21-23 September, 2010 in Orlando, Florida,. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, National Science Foundation (NSF), Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.

  5. Proceedings of the 2009 Monitoring Research Review: Ground-Based Nuclear Explosion Monitoring Technologies

    Energy Technology Data Exchange (ETDEWEB)

    Wetovsky, Marv A [Los Alamos National Laboratory; Aguilar - Chang, Julio [Los Alamos National Laboratory; Anderson, Dale [Los Alamos National Laboratory; Arrowsmith, Marie [Los Alamos National Laboratory; Arrowsmith, Stephen [Los Alamos National Laboratory; Baker, Diane [Los Alamos National Laboratory; Begnaud, Michael [Los Alamos National Laboratory; Harste, Hans [Los Alamos National Laboratory; Maceira, Monica [Los Alamos National Laboratory; Patton, Howard [Los Alamos National Laboratory; Phillips, Scott [Los Alamos National Laboratory; Randall, George [Los Alamos National Laboratory; Rowe, Charlotte [Los Alamos National Laboratory; Stead, Richard [Los Alamos National Laboratory; Steck, Lee [Los Alamos National Laboratory; Whitaker, Rod [Los Alamos National Laboratory; Yang, Xiaoning ( David ) [Los Alamos National Laboratory

    2009-09-21

    These proceedings contain papers prepared for the Monitoring Research Review 2009: Ground -Based Nuclear Explosion Monitoring Technologies, held 21-23 September, 2009 in Tucson, Arizona,. These papers represent the combined research related to ground-based nuclear explosion monitoring funded by the National Nuclear Security Administration (NNSA), Air Force Research Laboratory (AFRL), US Army Space and Missile Defense Command, Comprehensive Test Ban Treaty Organization (CTBTO), and other invited sponsors. The scientific objectives of the research are to improve the United States’ capability to detect, locate, and identify nuclear explosions. The purpose of the meeting is to provide the sponsoring agencies, as well as potential users, an opportunity to review research accomplished during the preceding year and to discuss areas of investigation for the coming year. For the researchers, it provides a forum for the exchange of scientific information toward achieving program goals, and an opportunity to discuss results and future plans. Paper topics include: seismic regionalization and calibration; detection and location of sources; wave propagation from source to receiver; the nature of seismic sources, including mining practices; hydroacoustic, infrasound, and radionuclide methods; on-site inspection; and data processing.

  6. De-mystifying earned value management for ground based astronomy projects, large and small

    Science.gov (United States)

    Norton, Timothy; Brennan, Patricia; Mueller, Mark

    2014-08-01

    The scale and complexity of today's ground based astronomy projects have justifiably required Principal Investigator's and their project teams to adopt more disciplined management processes and tools in order to achieve timely and accurate quantification of the progress and relative health of their projects. Earned Value Management (EVM) is one such tool. Developed decades ago and used extensively in the defense and construction industries, and now a requirement of NASA projects greater than $20M; EVM has gained a foothold in ground-based astronomy projects. The intent of this paper is to de-mystify EVM by discussing the fundamentals of project management, explaining how EVM fits with existing principles, and describing key concepts every project can use to implement their own EVM system. This paper also discusses pitfalls to avoid during implementation and obstacles to its success. The authors report on their organization's most recent experience implementing EVM for the GMT-Consortium Large Earth Finder (G-CLEF) project. G-CLEF is a fiber-fed, optical echelle spectrograph that has been selected as a first light instrument for the Giant Magellan Telescope (GMT), planned for construction at the Las Campanas Observatory in Chile's Atacama Desert region.

  7. Augmenting WFIRST Microlensing with a Ground-based Optical Telescope Network

    CERN Document Server

    Zhu, Wei

    2016-01-01

    Augmenting the WFIRST microlensing campaigns with intensive observations from a ground-based network of wide-field survey telescopes would have several major advantages. First, it would enable one-dimensional (1-D) microlens parallax measurements over the entire mass range $M\\gtrsim M_\\oplus$. For luminous lenses, such 1-D parallax measurements can be promoted to complete solutions (mass, distance, transverse velocity) by high-resolution imaging a few years after the observations. This would provide crucial information not only about the hosts of planets and other lenses, but also enable a much more precise Galactic model. The addition of such a ground-based survey would also yield full 2-D vector parallax measurements, with largest sensitivity to low-mass lenses, which (being non-luminous) are not subject to followup imaging. These 2-D parallax measurements will directly yield mass and distance measurements for most planetary and binary events. It would also yield additional complete solutions for single-len...

  8. Which future for electromagnetic Astronomy: Ground Based vs Space Borne Large Astrophysical Facilities

    Science.gov (United States)

    Ubertini, Pietro

    2015-08-01

    The combined use of large ground based facilities and large space observatories is playing a key role in the advance of astrophysics by providing access to the entire electromagnetic spectrum, allowing high sensitivity observations from the lower radio wavelength to the higher energy gamma rays.It is nowadays clear that a forward steps in the understanding of the Universe evolution and large scale structure formation is essential and only possible with the combined use of multiwavelength imaging and spectral high resolution instruments.The increasing size, complexity and cost of large ground and space observatories places a growing emphasis on international collaboration. If the present set of astronomical facilities is impressive and complete, with nicely complementary space and ground based telescopes, the scenario becomes worrisome and critical in the next two decades. In fact, only a few ‘Large’ main space missions are planned and there is a need to ensure proper ground facility coverage: the synergy Ground-Space is not escapable in the timeframe 2020-2030.The scope of this talk is to review the current astronomical instrumentation panorama also in view of the recent major national agencies and international bodies programmatic decisions.This Division B meeting give us a unique opportunity to review the current situation and discuss the future perspectives taking advantage of the large audience ensured by the IAU GA.

  9. 地基SAR干涉测量原理及其形变监测应用研究%Ground-based SAR Interferometry Principles and Its Applications to Displacement Monitoring

    Institute of Scientific and Technical Information of China (English)

    王鹏; 周校

    2012-01-01

    详细介绍了地基SAR的基本理论,结合建筑物二维和一维的实测数据,分析了其在距离向和方位向的分辨率以及形变的监测精度,说明了地基SAR在形变监测中的有效性,并对地基SAR今后的应用与发展作了初步展望。%We describe the basic theoretical principles for ground-based SAR, including stepped- frequency continuous wave, synthetic aperture radar and interferometric measurement. The anal-ysis of the measured monitoring data of a building structure in two-dimension and one-dimension shows the validity of ground-based SAR in ground deformation monitoring. We also make some preliminary look in applications and developments of ground-based SAR in future.

  10. AdS5×S(5) mirror model as a string sigma model.

    Science.gov (United States)

    Arutyunov, Gleb; van Tongeren, Stijn J

    2014-12-31

    Doing a double Wick rotation in the world sheet theory of the light cone AdS5×S(5) superstring results in an inequivalent, so-called mirror theory that plays a central role in the field of integrability in the AdS-CFT correspondence. We show that this mirror theory can be interpreted as the light cone theory of a free string on a different background. This background is related to dS5×H(5) by a double T-duality, and has hidden supersymmetry. The geometry can also be extracted from an integrable deformation of the AdS5×S(5) sigma model, and we prove the observed mirror duality of these deformed models at the bosonic level as a byproduct. While we focus on AdS5×S(5), our results apply more generally.

  11. A Demonstration of Wavefront Sensing and Mirror Phasing from the Image Domain

    CERN Document Server

    Pope, Benjamin; Cheetham, Anthony; Martinache, Frantz; Norris, Barnaby; Tuthill, Peter

    2014-01-01

    In astronomy and microscopy, distortions in the wavefront affect the dynamic range of a high contrast imaging system. These aberrations are either imposed by a turbulent medium such as the atmosphere, by static or thermal aberrations in the optical path, or by imperfectly phased subapertures in a segmented mirror. Active and adaptive optics (AO), consisting of a wavefront sensor and a deformable mirror, are employed to address this problem. Nevertheless, the non-common-path between the wavefront sensor and the science camera leads to persistent quasi-static speckles that are difficult to calibrate and which impose a floor on the image contrast. In this paper we present the first experimental demonstration of a novel wavefront sensor requiring only a minor asymmetric obscuration of the pupil, using the science camera itself to detect high order wavefront errors from the speckle pattern produced. We apply this to correct errors imposed on a deformable microelectromechanical (MEMS) segmented mirror in a closed l...

  12. The Active Mirror Control of the MAGIC Telescope

    CERN Document Server

    Biland, A; Anderhub, H; Danielyan, V; Hakobyan, D; Lorenz, E; Mirzoyan, R

    2007-01-01

    One of the main design goals of the MAGIC telescopes is the very fast repositioning in case of Gamma Ray Burst (GRB) alarms, implying a low weight of the telescope dish. This is accomplished by using a space frame made of carbon fiber epoxy tubes, resulting in a strong but not very rigid support structure. Therefore it is necessary to readjust the individual mirror tiles to correct for deformations of the dish under varying gravitational load while tracking an object. We present the concept of the Active Mirror Control (AMC) as implemented in the MAGIC telescopes and the actual performance reached. Additionally we show that also telescopes using a stiff structure can benefit from using an AMC.

  13. Manufacturing aspheric mirrors made of zero thermal expansion cordierite ceramics using Magnetorheological Finishing (MRF)

    Science.gov (United States)

    Sugawara, Jun; Maloney, Chris

    2016-07-01

    NEXCERATM cordierite ceramics, which have ultra-low thermal expansion properties, are perfect candidate materials to be used for light-weight satellite mirrors that are used for geostationary earth observation and for mirrors used in ground-based astronomical metrology. To manufacture the high precision aspheric shapes required, the deterministic aspherization and figure correction capabilities of Magnetorheological Finishing (MRF) are tested. First, a material compatibility test is performed to determine the best method for achieving the lowest surface roughness of RMS 0.8nm on plano surfaces made of NEXCERATM ceramics. Secondly, we will use MRF to perform high precision figure correction and to induce a hyperbolic shape into a conventionally polished 100mm diameter sphere.

  14. More questions for mirror neurons.

    Science.gov (United States)

    Borg, Emma

    2013-09-01

    The mirror neuron system is widely held to provide direct access to the motor goals of others. This paper critically investigates this idea, focusing on the so-called 'intentional worry'. I explore two answers to the intentional worry: first that the worry is premised on too limited an understanding of mirror neuron behaviour (Sections 2 and 3), second that the appeal made to mirror neurons can be refined in such a way as to avoid the worry (Section 4). I argue that the first response requires an account of the mechanism by which small-scale gestures are supposedly mapped to larger chains of actions but that none of the extant accounts of this mechanism are plausible. Section 4 then briefly examines refinements of the mirror neuron-mindreading hypothesis which avoid the intentional worry. I conclude that these refinements may well be plausible but that they undermine many of the claims standardly made for mirror neurons. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Metamaterial mirrors in optoelectronic devices

    KAUST Repository

    Esfandyarpour, Majid

    2014-06-22

    The phase reversal that occurs when light is reflected from a metallic mirror produces a standing wave with reduced intensity near the reflective surface. This effect is highly undesirable in optoelectronic devices that use metal films as both electrical contacts and optical mirrors, because it dictates a minimum spacing between the metal and the underlying active semiconductor layers, therefore posing a fundamental limit to the overall thickness of the device. Here, we show that this challenge can be circumvented by using a metamaterial mirror whose reflection phase is tunable from that of a perfect electric mirror († = €) to that of a perfect magnetic mirror († = 0). This tunability in reflection phase can also be exploited to optimize the standing wave profile in planar devices to maximize light-matter interaction. Specifically, we show that light absorption and photocurrent generation in a sub-100 nm active semiconductor layer of a model solar cell can be enhanced by ∼20% over a broad spectral band. © 2014 Macmillan Publishers Limited.

  16. Monitoring greenhouse gas emissions in Australian landscapes: Comparing ground based mobile surveying data to GOSAT observations

    Science.gov (United States)

    Bashir, S.; Iverach, C.; Kelly, B. F. J.

    2016-12-01

    Climate change is threatening the health and stability of the natural world and human society. Such concerns were emphasized at COP21 conference in Paris 2015 which highlighted the global need to improve our knowledge of sources of greenhouse gas and to develop methods to mitigate the effects of their emissions. Ongoing spatial and temporal measurements of greenhouse gases at both point and regional scales is important for clarification of climate change mechanisms and accounting. The Greenhouse gas Observing SATellite (GOSAT) is designed to monitor the global distribution of carbon dioxide (CO2) and methane (CH4) from orbit. As existing ground monitoring stations are limited and still unevenly distributed, satellite observations provide important frequent, spatially extensive, but low resolution observations. Recent developments in portable laser based greenhouse gas measurement systems have enabled the rapid measurement of greenhouse gases in ppb at the ground surface. This study was conducted to map major sources of CO2 and CH4 in the eastern states of Australia at the landscape scale and to compare the results to GOSAT observations. During April 2016 we conducted a regional CH4 and CO2 mobile survey, using an LGR greenhouse gas analyzer. Measurements were made along a 4000 KM circuit through major cities, country towns, dry sclerophyll forests, coastal wetlands, coal mining regions, coal seam gas developments, dryland farming and irrigated agricultural landscapes. The ground-based survey data were then compared with the data (L2) from GOSAT. Ground-based mobile surveys showed that there are clear statistical differences in the ground level atmospheric concentration of CH4 and CO2 associated with all major changes in land use. These changes extend for kilometers, and cover one or more GOSAT pixels. In the coal mining districts the ground-level atmospheric concentration of CH4 exceeded 2 ppm for over 40 km, yet this was not discernable in the retrieved data (L2

  17. Aerosol Single Scattering Albedo retrieved from ground-based measurements in the UV-visible

    Directory of Open Access Journals (Sweden)

    V. Buchard

    2010-07-01

    Full Text Available Estimates of Aerosol Single Scattering Albedo (SSA from ground-based spectral measurements in the UV-visible are conducted at Villeneuve d'Ascq (VdA in France. In order to estimate this parameter, measurements of global and diffuse UV-visible solar irradiances performed under cloud-free conditions since 2003 with a spectroradiometer operated by the Laboratoire d'Optique Atmosphérique (LOA are used. The technique consists in comparing the measured irradiance values to modelled irradiances computed for various SSA. The retrieval is restricted to the 330–450 nm range to avoid ozone influence.

    For validation purpose, the retrieved values of SSA at 440 nm are compared to the ones obtained from sunphotometer measurements of the AERONET/PHOTONS network available on the LOA site. The results are rather satisfying: in 2003 and 2005–2006 the Root Mean Square (RMS of the differences are about 0.05, these values are within the uncertainty domain of retrieval of both products. Distinction between days characterized by different aerosol content, by means of the aerosol optical thickness (AOT retrieved from ground-based measurements at the same wavelength, shows that the comparisons between both products are better when AOT are higher. Indeed in case AOT are greater than 0.2, the RMS is 0.027 in 2003 and 0.035 in 2005–2006. The SSA estimated at 340 and 380 nm from ground-based spectra are also studied, though no validation can be carried out with sunphotometer data (440 nm is the shortest wavelength at which the SSA is provided by the network. The good comparisons observed at 440 nm can let assume that the SSA retrieved from spectroradiometer measurements at the two other wavelengths are also obtained with a good confidence level. Thus these values in the UV range can be used to complete aerosol data provided by AERONET/PHOTONS at VdA. Moreover they can be used for a best knowledge of the aerosol absorption that is necessary to quantify the

  18. Investigation of Rainfall Characteristics Using TRMM PR and Ground Based Radar

    Science.gov (United States)

    Dolan, B.; Lang, T. J.; Nesbitt, S. W.; Cifelli, R.; Rutledge, S. A.

    2011-12-01

    Despite relatively good agreement between reflectivity profiles, comparisons of rainfall statistics derived from TRMM Precipitation Radar (PR) deviate from ground-based radar (GR) observations in various field locations across the globe. TRMM PR rain rate probability distribution functions underestimate the occurrence of high rain rates (> 80 mm hr-1) compared with similar ground-based statistics, and similarly, GR distributes the total rain volume over a larger range of rain rates. Analysis of ten years of TRMM data over three field sites has shown that the greatest disagreements occur in the most intense convection, such as over land and during the east and break wind regimes over the Amazon and Australia, respectively. These differences are investigated further in this study. Ten years of TRMM PR data are analyzed in conjunction with data collected during two field experiments involving the NCAR S-Pol radar. S-Pol was deployed in Brazil in the Amazon during TRMM LBA in 1998-1999 and near Mazatlan, Mexico as part of the North American Monsoon Experiment (NAME) in 2004. Additionally, multiple years of data from the Australian Bureau of Meteorology CPOL radar located in Darwin, Australia, are examined to extend the robustness of the GR observations beyond the relatively short field campaigns. Polarimetric data collected by the two radars are used to characterize the differences between TRMM PR and GR observations as a function of bulk hydrometeor type. For example, profiles with significant graupel, as identified by GR, are analyzed to investigate the role of mixed phase in the PR retrievals. The vertical variability of D0 is examined as a function of reflectivity and related to the underlying microphysical conditions using the polarimetric data provided by the GR observations. Spatial variability of D0 is also explored by correlating D0 values derived from GR at different heights. Several significant changes were made to the TRMM processing algorithms in the

  19. Ground-based Observations of the Solar Sources of Space Weather

    Science.gov (United States)

    Veronig, A. M.; Pötzi, W.

    2016-04-01

    Monitoring of the Sun and its activity is a task of growing importance in the frame of space weather research and awareness. Major space weather disturbances at Earth have their origin in energetic outbursts from the Sun: solar flares, coronal mass ejections and associated solar energetic particles. In this review we discuss the importance and complementarity of ground-based and space-based observations for space weather studies. The main focus is drawn on ground-based observations in the visible range of the spectrum, in particular in the diagnostically manifold Hα spectral line, which enables us to detect and study solar flares, filaments (prominences), filament (prominence) eruptions, and Moreton waves. Existing Hα networks such as the GONG and the Global High-Resolution Hα Network are discussed. As an example of solar observations from space weather research to operations, we present the system of real-time detection of Hα flares and filaments established at Kanzelhöhe Observatory (KSO; Austria) in the frame of the space weather segment of the ESA Space Situational Awareness programme (swe.ssa.esa.int). An evaluation of the system, which is continuously running since July 2013 is provided, covering an evaluation period of almost 2.5 years. During this period, KSO provided 3020 hours of real-time Hα observations at the ESA SWE portal. In total, 824 Hα flares were detected and classified by the real-time detection system, including 174 events of Hα importance class 1 and larger. For the total sample of events, 95 % of the automatically determined flare peak times lie within ±5 min of the values given in the official optical flares reports (by NOAA and KSO), and 76 % of the start times. The heliographic positions determined are better than ±5°. The probability of detection of flares of importance 1 or larger is 95 %, with a false alarm rate of 16 %. These numbers confirm the high potential of automatic flare detection and alerting from ground-based

  20. Ground-based follow-up in relation to Kepler asteroseismic investigation

    Science.gov (United States)

    Uytterhoeven, K.; Briquet, M.; Bruntt, H.; De Cat, P.; Frandsen, S.; Gutiérrez-Soto, J.; Kiss, L.; Kurtz, D. W.; Marconi, M.; Molenda-Żakowicz, J.; Østensen, R.; Randall, S.; Southworth, J.; Szabó, R.

    2010-12-01

    The Kepler space mission, successfully launched in March 2009, is providing continuous and high-precision photometry of thousands of stars simultaneously. The uninterrupted time-series of stars of all known pulsation types are a precious source for asteroseismic studies. The Kepler data do not provide information on the physical parameters, such as T_eff, log g, metallicity, and v sin i, which are crucial for successful asteroseismic modelling. Additional ground-based time-series data are needed to characterize mode parameters in several types of pulsating stars. Therefore, ground-based multi-colour photometry and mid/high-resolution spectroscopy are needed to complement the space data. We present ground-based activities within KASC on selected asteroseismic Kepler targets of several pulsation types. Based on observations made with the Isaac Newton Telescope and William Herschel Telescope operated by the Isaac Newton Group, with the Nordic Optical Telescope, operated jointly by Denmark, Finland, Iceland, Norway, and Sweden, with the Italian Telescopio Nazionale Galileo (TNG) operated by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica), and with the Mercator telescope, operated by the Flemish Community, all on the island of La Palma at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (IAC). Based on observations made with the IAC-80 operated on the island of Tenerife by the IAC at the Spanish Observatorio del Teide. Also based on observations taken at the observatories of Sierra Nevada, San Pedro Mártir, Vienna, Xinglong, Apache Point, Lulin, Tautenburg, McDonald, Skinakas, Pic du Midi, Mauna Kea, Steward Observatory, Mt. Wilson, Białków Observatory of the Wrocław University, Piszkésteto Mountain Station, and Observatoire de Haute Provence. Based on spectra taken at the Loiano (INAF - OA Bologna), Serra La Nave (INAF - OA Catania) and Asiago (INAF - OA Padova) observatories. Also