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Sample records for adaptive secondary mirrors

  1. Static and dynamic responses of an ultrathin adaptive secondary mirror

    NASA Astrophysics Data System (ADS)

    del Vecchio, Ciro; Brusa, Guido; Gallieni, Daniele; Lloyd-Hart, Michael; Davison, Warren B.

    1999-09-01

    We present the results of a compete set of static and dynamic runs of the FEA model of the MMT adaptive secondary. The thin mirror is the most delicate component of the MMT adaptive secondary unit, as it provides the deformable optical surface able to correct the incoming wavefront. The static performances are evaluated as a function of the various load cases arising form gravitational loads and from the forces deriving from the magnetic interactions between actuators. In addition, computations were performed to assess the dynamic response to the high bandwidth, adaptive correcting force.s In both cases, the performances of the adaptive mirror design are able to accommodate the severe specifications.

  2. Design of an Adaptive Secondary Mirror: A Global Approach

    NASA Astrophysics Data System (ADS)

    Brusa, Guido; del Vecchio, Ciro

    1998-07-01

    We present the mechanical and actuator design of an adaptive secondary mirror that matches the optical requirements of the active and adaptive corrections. Conceived for the particular implementation for the 6.5-m conversion of the multiple-mirror telescope, with small variations of the input parameters this study is suitable for applications for telescopes of the same class. We found that a three-layer structure, i.e., a thin deformable shell, a thick reference plate, and a third plate that acts as actuator support and heat sink, is able to provide the required mechanical stability and actuator density. We also found that a simple electromagnetic actuator can be used. This actuator, when optimized, will dissipate a typical power of a few tenths of watts.

  3. Numerical simulations of the LBT adaptive secondary mirror

    NASA Astrophysics Data System (ADS)

    Del Vecchio, Ciro; Gallieni, Daniele

    2000-07-01

    In this paper we describe the design of the deformable mirror of the Large Binocular Telescope adaptive secondary unit. Starting from the optical design, a numerical model of the ultra-thin, aspherical glass shell, accommodating the 918 magnets on the selected actuator geometry, has been run. As a result, we can evaluate the response of this crucial component of the telescope optics with great accuracy. The DM is analyzed from the mechanical standpoint -- gravity deformations, wavefront residue, residue of low-order Zernike aberrations, corrections of magnetic interactions -- in order to compute the optical performances in the most demanding operational circumstances.

  4. Optical fabrication of the MMT adaptive secondary mirror

    NASA Astrophysics Data System (ADS)

    Martin, Hubert M.; Burge, James H.; Del Vecchio, Ciro; Dettmann, Lee R.; Miller, Stephen M.; Smith, Bryan K.; Wildi, Francois P.

    2000-07-01

    We describe the optical fabrication of the adaptive secondary mirror for the MMT. The 640 mm f/15 secondary consists of a flexible glass shell, 1.8 mm thick, whose shape is controlled by 336 electromagnetic actuators. It is designed to give diffraction-limited images at a wavelength of 1 micron. For generating and polishing, the shell was supported by attaching it to a rigid glass blocking body with a thin layer of pitch. It could then be figured and measured using techniques developed for rigid secondaries. The highly aspheric surface was polished with a 30 cm stressed lap and small passive tools, and measured using a swing-arm profilometer and a holographic test plate. The goal for fabrication was to produce diffraction-limited images in the visible, after simulated adaptive correction using only a small fraction of the typical actuator forces. This translates into a surface accuracy of less than 19 nm rms with correction forces of less than 0.05 N rms. We achieved a surface accuracy of 8 nm rms after simulated correction with forces of 0.02 N rms.

  5. The adaptive secondary mirror for the 6.5 conversion of the Multiple Mirror Telescope

    NASA Astrophysics Data System (ADS)

    Riccardi, Armando; Brusa, Guido; Del Vecchio, Ciro; Baisi, Roberto; Andrighettoni, M.; Gallieni, Daneile; Zocchi, F.; Lloyd-Hart, Michael; Martin, Hubert M.; Wildi, François

    We present the laboratory results performed by the non-conventional secondary mirror that will be used as corrector for the adaptive optics system of the 6.5m conversion of MMT. The design of the unit consists of a 2mm-thick 642mm-diameter convex deformable mirror whose figure is controlled by 336 electro-magnetic force actuators, a thick shell used as position reference and an aluminum shell as actuator support and cooling. The actuator forces are controlled using feed-forward and de-centralized closed loop compensation thanks to the 40kHz feedback signals from the 336 capacitive position sensors. The digital real-time control and the unit monitoring is obtained using custom-made on-board electronics based on 168 DSPs. This paper will report on extensive static and dynamical measurements aimed at characterize the mirror response function, that shows a proper atmospheric turbulence compensation.

  6. Adaptive secondary mirror for the 6.5-m conversion of the Multiple Mirror Telescope: first laboratory testing results

    NASA Astrophysics Data System (ADS)

    Brusa, Guido; Riccardi, Armando; Biliotti, Valdemaro; del Vecchio, Ciro; Salinari, Piero; Stefanini, Paolo; Mantegazza, Paolo; Biasi, Roberto; Andrighettoni, Mario; Franchini, Claudio; Gallieni, Daniele

    1999-09-01

    We present the first results of test performed on a reduced size adaptive secondary prototype named P36. The full size unit, named MMT336, is ready to be assembled and it is planned to install it at the 6.5m conversion of the Multiple Mirror Telescope by the end of this year. The design of the final unit consists of: a convex thin deformable mirror whose figure is controlled by 336 electro-magnetic force actuators, a thick reference shell and a third aluminum shell used for actuator support and cooling. The force actuator response function is adjusted using both open and closed loop compensation to obtain an equivalent position actuator thanks to nearly co-located capacitive position sensors. The digital real-time control and the unit monitoring is done using custom-made electronics based on DSPs. The preliminary dynamical test aimed at identifying the P36 mirror response function to obtain a proper dynamics compensation were successful. In fact two main results have been obtained: 1) an accurate identification of the feedforward matrix used to control the mirror 2) settling time of approximately 0.5 ms, well within the specifications. We also complement these lab results with results obtained from simulations of the full size mirror dynamics.

  7. Aluminum reference plate, heat sink, and actuator design for an adaptive secondary mirror

    NASA Astrophysics Data System (ADS)

    del Vecchio, Ciro

    1998-09-01

    The design of an adaptive secondary mirror has to satisfy many requirements coming from different fields. The thin mirror must be actuated very precisely with a large bandwidth. The reference plate has to provide a high stability reference for the optical surfaces. The local seeing is not to be degraded by any significant thermal perturbation. In this article, the performances of a configuration with a single aluminum reference plate, that also provides the heat sink, are computed starting from the input power coming from the magnetic actuators, whose magnetic design has been revised.

  8. The adaptive secondary mirrors for the Large Binocular Telescope: a progress report

    NASA Astrophysics Data System (ADS)

    Riccardi, Armando; Brusa, Guido; Xompero, Marco; Zanotti, Daniela; Del Vecchio, Ciro; Salinari, Piero; Ranfagni, Piero; Gallieni, Daniele; Biasi, Roberto; Andrighettoni, Mario; Miller, Steve; Mantegazza, Paolo

    2004-10-01

    The two 911mm-diameter adaptive secondary (AS) mirrors for the Large Binocular telescope (LBT) are currently under manufacturing process. Each unit has 672 electro-magnetic force actuators. They control the figure of the Gregorian secondary 1.6mm-thick mirrors with an internal loop using the signal of co-located capacitive sensors. The obtained computational power of the on-board control electronics allows to use it as real-time computer for wavefront reconstruction. We present the progress in manufacturing and assembling of the first telescope unit, the progress in software production, the status of the testing facilities and an update on the latest modification of the design.

  9. Stress polishing of thin shells for adaptive secondary mirrors. Application to the Very Large Telescope deformable secondary

    NASA Astrophysics Data System (ADS)

    Hugot, E.; Ferrari, M.; Riccardi, A.; Xompero, M.; Lemaître, G. R.; Arsenault, R.; Hubin, N.

    2011-03-01

    Context. Adaptive secondary mirrors (ASM) are, or will be, key components on all modern telescopes, providing improved seeing conditions or diffraction limited images, thanks to the high-order atmospheric turbulence correction obtained by controlling the shape of a thin mirror. Their development is a key milestone towards future extremely large telescopes (ELT) where this technology is mandatory for successful observations. Aims: The key point of actual adaptive secondaries technology is the thin glass mirror that acts as a deformable membrane, often aspheric. On 6 m - 8 m class telescopes, these are typically 1 m-class with a 2 mm thickness. The optical quality of this shell must be sufficiently good not to degrade the correction, meaning that high spatial frequency errors must be avoided. The innovative method presented here aims at generating aspherical shapes by elastic bending to reach high optical qualities. Methods: This method is called stress polishing and allows generating aspherical optics of a large amplitude with a simple spherical polishing with a full sized lap applied on a warped blank. The main advantage of this technique is the smooth optical quality obtained, free of high spatial frequency ripples as they are classically caused by subaperture toolmarks. After describing the manufacturing process we developed, our analytical calculations lead to a preliminary definition of the geometry of the blank, which allows a precise bending of the substrate. The finite element analysis (FEA) can be performed to refine this geometry by using an iterative method with a criterion based on the power spectral density of the displacement map of the optical surface. Results: Considering the specific case of the Very Large Telescope (VLT) deformable secondary mirror (DSM), extensive FEA were performed for the optimisation of the geometry. Results are showing that the warping will not introduce surface errors higher than 0.3 nm rms on the minimal spatial scale

  10. The adaptive secondary mirror for the Large Binocular Telescope: results of acceptance laboratory test

    NASA Astrophysics Data System (ADS)

    Riccardi, A.; Xompero, M.; Zanotti, D.; Busoni, L.; Del Vecchio, C.; Salinari, P.; Ranfagni, P.; Brusa Zappellini, G.; Biasi, R.; Andrighettoni, M.; Gallieni, D.; Anaclerio, E.; Martin, H. M.; Miller, S. M.

    2008-07-01

    The first of the two Gregorian Adaptive Secondary Mirror (ASM) units for the Large Binocular Telescope (LBT) has been fully integrated and tested for laboratory acceptance. The LBT unit represents the most advanced ASM device existing in hardware. The unit has 672 electro-magnetic force actuators to change the shape of the 1.6mm-thick and 911mm-diameter Zerodur shell. The actuators control the mirror figure using the position feedback from the internal metrology provided by co-located capacitive sensors. The on-board real-time control electronics has a parallel computational power of 163Gflop/s providing not only the internal control of the unit with a 72kHz loop but also the wavefront reconstruction for the 1kHz Adaptive Optics loop. The paper describes the final configuration of the system and reports the results of the characterization and optimization process together with the results of the laboratory acceptance tests.

  11. The LBT experience of adaptive secondary mirror operations for routine seeing- and diffraction-limited science operations

    NASA Astrophysics Data System (ADS)

    Guerra, J. C.; Brusa, G.; Christou, J.; Miller, D.; Ricardi, A.; Xompero, M.; Briguglio, R.; Wagner, M.; Lefebvre, M.; Sosa, R.

    2013-09-01

    The Large Binocular Telescope (LBT) is unique in that it is currently the only large telescope (2 x 8.4m primary mirrors) with permanently mounted adaptive secondary mirrors (ASMs). These ASMs have been used for regular observing since early 2010 on the right side and since late 2011 on the left side. They are currently regularly used for seeing-limited observing as well as for selective diffraction-limited observing and are required to be fully operational every observing night. By comparison the other telescopes using ASMs, the Multi Mirrot Telescope (MMT) and more recently Magellan, use fixed secondaries of seeing-limited observing and switch in the ASMs for diffraction-limited observing. We will discuss the night-to-night operational requirements for ASMs specifically for seeing-limited but also for diffraction-limited observations based on the LBT experience. These will include preparation procedures for observing (mirror flattening and resting as examples); hardware failure statistics and how to deal with them such as for the actuators; observing protocols for; and current limitations of use due to the ASM technology such as the minimum elevation limit (25 degrees) and the hysteresis of the gravity-vector induced astigmatism. We will also discuss the impact of ASM maintenance and preparation

  12. Full-system laboratory testing of the F/15 deformable secondary mirror for the new MMT adaptive optics system

    NASA Astrophysics Data System (ADS)

    Mcguire, Patrick C.; Lloyd-Hart, Michael; Angel, J. Roger P.; Angeli, George Z.; Johnson, Robert L.; Fitz-Patrick, Bruce C.; Davison, Warren B.; Sarlot, Roland J.; Bresloff, Cynthia J.; Hughes, John M.; Miller, Stephen M.; Schaller, Skip; Wildi, Francois P.; Kenworthy, Matthew A.; Cordova, Richard M.; Rademacher, Matthew J.; Rascon, Mario H.; Burge, James H.; Stamper, Brian L.; Zhao, Chunyu; Salinari, Piero; del Vecchio, Ciro; Riccardi, Armando; Brusa, Guido; Biasi, Roberto; Andrighettoni, Mario; Gallieni, Daniele; Franchini, Claudio; Sandler, David G.; Barrett, Todd K.

    1999-09-01

    We will present a system to perform closed-loop optical tests of the 64 cm diameter, 336 actuator adaptive secondary made at the Steward Observatory Mirror Laboratory. Testing will include Shack-Hartmann wavefront sensing and modal correction of static and dynamic aberrated wavefronts. The test optical system is designed so that experiments can be made with both the focal plane instrument and secondary installed in their normal configuration at the MMT, or with the same 9 m spacing in a laboratory test tower. The convex secondary will be illuminated at normal incidence through two 70 cm diameter lenses mounted just below. The artificial, aberrated star is projected from near the wavefront sensor in the Cassegrain focus assembly. Computer generated holograms correct for spherical aberration in the really optics at the test wavelengths of 0.594 and 1.5 micrometers . Atmospheric turbulence is reproduced by two spinning transmission plates imprinted with Kolmogorov turbulence. The Shimmulator will give us the opportunity to test fully the adaptive optics system before installation at the new MMT, hence saving much precious telescope time.

  13. JWST Secondary Mirror Deploy Timelapse

    NASA Video Gallery

    Setting up NASA's James Webb Space Telescope's secondary mirror in space will require special arms that resemble a tripod that was recently demonstrated in a NASA cleanroom. TRT: 1:25 / Credit: NAS...

  14. Giant segmented adaptive mirrors: progress report

    NASA Astrophysics Data System (ADS)

    Riccardi, Armando; Biasi, Roberto; Brusa, Guido; Del Vecchio, Ciro; Esposito, Simone; Gallieni, Daniele; Salinari, Piero

    2003-01-01

    We show that the same technology developed for MMT and LBT Adaptive Secondary mirrors can be used for building segmented adaptive mirrors of essentially any size. This seems to be at the moment the most promising approach to provide the enormous number of degrees of freedom necessary for adaptive correction at visual wavelengths in giant telescopes. In this paper we recall the analytical formulation of the problem and we report recent numerical studies and initial experimental results obtained with prototype actuators for large adaptive segments.

  15. MMT adaptive secondary prototype development

    NASA Astrophysics Data System (ADS)

    Biasi, Roberto; Gallieni, Daniele

    1998-09-01

    We designed and manufacture dan 'Adaptive Secondary Mirror 30 Actuators Prototype' that represents as much as possible the final MMT adaptive optics unit for what concerns mechanical, electronic and cooling system issues. Moreover, different actuator designs have been tested by using the same test bench. The adaptive secondary is based on a thin continuous facesheet mirror moved by electromagnetic actuators. Permanent magnets are glued on the mirror, while voice coils are connected to the support structure by cold fingers. A capacitive sensor co-located with each actuator measures the local gap between the mirror and a reference back plate. Voice coil motors allow to perform chopping and tip-tilt correction by using directly the deformable mirror. Actuators pitch is set to achieve high order correction in the visible wavelength.

  16. LBT adaptive secondary preliminary design

    NASA Astrophysics Data System (ADS)

    Gallieni, Daniele; Del Vecchio, Ciro; Anaclerio, E.; Lazzarini, P. G.

    2000-07-01

    We report on the design of the two Gregorian adaptive secondary mirrors of the Large Binocular Telescope. Each adaptive secondary is a Zerodur shell having an external diameter of 911 mm and a thickness of about 1.5 mm. The deformable mirror is controlled by a pattern of 918 electromagnetic actuators. Its shape is referred to a stable ULE back plate by means of capacitive sensors co-located to the actuators pattern. The preliminary design of the system is addressed with particular attention to the reference plate optimization.

  17. The VST secondary mirror support system

    NASA Astrophysics Data System (ADS)

    Schipani, P.; Perrotta, F.; Molfese, C.; Caputi, O.; Ferragina, L.; Marty, L.; Capaccioli, M.; Gallieni, D.; Fumi, P.; Anaclerio, E.; Lazzarini, P.; De Paris, G.

    2008-07-01

    The VST telescope is equipped with an active optics system based on a wavefront sensor, a set of axial actuators to change the primary mirror shape and a secondary mirror positioner stage. The secondary mirror positioning capability allows the correction of defocus and coma optical aberrations, mainly caused by incorrect relative positions of the optics. The secondary mirror positioner is a 6-6 Stewart platform (also called "hexapod"). It is a parallel robot with a mobile platform moved by 6 linear actuators acting simultaneously. This paper describes the secondary mirror support system and the current status of the work.

  18. Adaptive secondary mirror for the 6.5-m conversion of the Multiple Mirror Telescope: latest laboratory test results of the P36 prototype

    NASA Astrophysics Data System (ADS)

    Riccardi, Armando; Brusa, Guido; Biliotti, Valdemaro; Del Vecchio, Ciro; Salinari, Piero; Stefanini, Paolo; Mantegazza, Paolo; Biasi, Roberto; Andrighettoni, Mario; Franchini, Claudio; Gallieni, Daniele; Lloyd-Hart, Michael; McGuire, Patrick C.; Miller, Stephen M.; Martin, Hubert M.

    2000-07-01

    The 336-actuator adaptive secondary unit (MMT336) for the new MMT is being assembled in Italy and will be delivered in June 2000 for the acceptance test at Steward Observatory (Tucson, AZ). The latest results obtained on a reduced-size (36 actuators) prototype called P36 are reported, confirming a settling time less than 1 ms measured in previous tests. The flattening procedure has been successfully tested on the P36 unit, reducing the initial surface error of 1.1 micrometer down to 43 nm rms. Moreover the dynamical tests on the P36 unit show that the system is able to attenuate the atmospheric-induced error from 466 nm to 31 nm rms. This in the case of median seeing condition at MMT (0.75 arcsec) a high wind speed (48 m/s) and a 1 kHz command rate per actuator. Finally, in the same conditions the atmospheric error is effectively attenuated up to a frequency of 100 Hz (OdB attenuation level).

  19. ZERODUR for lightweight secondary/tertiary mirrors

    NASA Astrophysics Data System (ADS)

    Morian, Hans F.; Mackh, Reiner

    1998-08-01

    ZERODUR, the glass ceramic, with CTE values near zero, has excellent performance up to 8.2 m primary mirrors as well as for lightweight (LW) mirrors for Secondaries and Tertiaries. The high homogeneity of major properties of ZERODUR is an important prerequisite for the LW production and application. The production of CNC grinding and subsequent lightening via acid etching for additional weight reduction will be discussed. Results of Secondary and Tertiary LW mirrors for advanced technology telescopes like 8 m, 6.5 m and 3.5 m telescopes will be addressed. This paper presents also some examples of space based satellites with LW Zerodur mirrors in use since several years.

  20. Development of GMT fast steering secondary mirror assembly

    NASA Astrophysics Data System (ADS)

    Cho, Myung; Corredor, Andrew; Dribusch, Christoph; Park, Won Hyun; Muller, Gary; Johns, Matt; Hull, Charlie; Kern, Jonathan; Kim, Young-Soo

    2014-07-01

    The Giant Magellan Telescope (GMT) is one of Extremely large telescopes, which is 25m in diameter featured with two Gregorian secondary mirrors, an adaptive secondary mirror (ASM) and a fast-steering secondary mirror (FSM). The FSM is 3.2 m in diameter and built as seven 1.1 m diameter circular segments conjugated 1:1 to the seven 8.4m segments of the primary. The guiding philosophy in the design of the FSM segment mirror is to minimize development and fabrication risks ensuring a set of secondary mirrors are available on schedule for telescope commissioning and early operations in a seeing limited mode. Each FSM segment contains a tip-tilt capability for fine co-alignment of the telescope subapertures and fast guiding to attenuate telescope wind shake and mount control jitter, thus optimizing the seeing limited performance of the telescope. The final design of the FSM mirror and support system configuration was optimized using finite element analyses and optical performance analyses. The optical surface deformations, image qualities, and structure functions for the gravity print-through cases, thermal gradient effects, and dynamic performances were evaluated. The results indicated that the GMT FSM mirror and its support system will favorably meet the optical performance goals for residual surface error and the FSM surface figure accuracy requirement defined by encircled energy (EE80) in the focal plane. The mirror cell assembly analysis indicated an excellent dynamic stiffness which will support the goal of tip-tilt operation.

  1. Lightweighted secondary mirror for the United Kingdom Infrared Telescope

    NASA Astrophysics Data System (ADS)

    Rohloff, Ralf-Rainer; Pitz, Eckhart; Hawarden, Timothy G.; Rees, Nicholas P.; Atad-Ettedgui, Eli; Kaufmann, Horst W.; Schmadel, Lutz

    1999-10-01

    The paper describes the manufacture and testing of a lightweighted Zerodur secondary mirror for the United Kingdom Infrared Telescope on Mauna Kea, Hawaii. The 313 mm diameter mirror is mounted on a Piezo platform for fast tip/tilt corrections. Therefore, the mirror mass has to be minimized to achieve high dynamic properties of the adaptive tip/tilt platform. The goal was to test the convex secondary without large auxiliary optics (Hindle sphere). We measured the mirror through the back surface using a small null lens system. A special transparent and highly homogeneous Zerodur was used for this purpose. We demonstrate that grinding a honeycomb structure and acid-etching of the back side of the mirror does not affect the figure of the polished convex surface.

  2. A deformable secondary mirror for the VLT

    NASA Astrophysics Data System (ADS)

    Arsenault, R.; Biasi, R.; Gallieni, D.; Riccardi, A.; Lazzarini, P.; Hubin, N.; Fedrigo, E.; Donaldson, R.; Oberti, S.; Stroebele, S.; Conzelmann, R.; Duchateau, M.

    2006-06-01

    ESO has initiated in June 2004 a feasibility study to investigate the possibility to retro-fit one of the VLT 8 m telescope with a deformable secondary mirror (DSM). The scope of this effort has been broadened to a concept of Adaptive Optics Facility (adaptive telescope with adapted instrument park). The feasibility study, conducted by MicroGate, ADS Intl and the INAF-Osservatorio Astrofisico di Arcetri, has been successful (no show stopper identified) and has provided an elegant design of an alternate M2-Unit for the VLT. It features a 1170 actuators DSM based on the voice coil force actuators coupled with capacitive sensors. An 80 kHz internal control loop allows implementing of electronic damping. The simulations performed have shown a fitting error of 62.5 nm rms (r ° = 12.1 cm @ 30 deg. zenith) with a 2mm thin shell and 1.5 kW of heat dissipation. The design shall provide a full stroke of ~50 μm and a rise time of < 1 msec. The DSM will be focused and "centered" by a Hexapod and a bi-positions electro-mechanism will allow switching from Nasmyth to Cassegrain focus configuration. Several features are planned to ease maintenance and diagnostic.

  3. The secondary mirror concept for the European Extremely Large Telescope

    NASA Astrophysics Data System (ADS)

    Mueller, Michael; Cayrel, Marc; Bonnet, Henri; Ciattaglia, Emanuela; Esselborn, Michael; Koch, Franz; Kurlandczyk, Herve; Pettazzi, Lorenzo; Rakich, Andrew; Sedghi, Babak

    2014-07-01

    The E-ELT is an active and adaptive 39-m telescope, with an anastigmat optical solution (5 mirrors including two flats), currently being developed by the European Southern Observatory (ESO). The convex 4-metre-class secondary mirror (M2) is a thin Zerodur meniscus passively supported by an 18 point axial whiffletree. A warping harness system allows to correct low order deformations of the M2 Mirror. Laterally the mirror is supported on 12 points along the periphery by pneumatic jacks. Due to its high optical sensitivity and the telescope gravity deflections, the M2 unit needs to allow repositioning the mirror during observation. Considering its exposed position 30m above the primary, the M2 unit has to provide good wind rejection. The M2 concept is described and major performance characteristics are presented.

  4. Primary adaptive mirrors for ELTs: a report on preliminary studies

    NASA Astrophysics Data System (ADS)

    Riccardi, Armando; Del Vecchio, Ciro; Salinari, Piero; Brusa, Guido; Lardiere, Olivier; Gallieni, Daniele; Biasi, Roberto; Mantegazza, Paolo

    2004-07-01

    At the moment the best bet to obtain an extremely high actuator density for extremely large pupils seems to be that of extending the current adaptive secondary mirror technology to segmented "adaptive primaries." The main components of a segment of an adaptive primary mirror are beng studied in order to determine all the parameters able to statically keep the mechanical response within the optical specifications and to dynamically provide the stiffness and damping features needed by the adaptive optics control system. Both static and dynamical requirements depend critically on actuator geometry and structure, mirror shape and thickness, and implementation of the control system. The mechanical response has been numerically evaluated in terms of deformation under gravity, mirror influence functions and actuator layout, including their interface to the shell.

  5. Hexapod kinematics for secondary mirror aberration control .

    NASA Astrophysics Data System (ADS)

    Schipani, P.

    This work deals with active correction of the aberrations in a telescope by moving the secondary mirror. A special attention is dedicated to the case of a secondary mirror whose motions are controlled by a 6-6 Stewart Platform (generally called by astronomers simply "hexapod", even if this term is more general). The kinematics of the device is studied. The non trivial forward kinematics problem is solved by an iterative algorithm fitting the necessities of an active optics system and fast enough to be used in a closed loop feedback control.

  6. Wind responses of the LSST secondary mirror

    NASA Astrophysics Data System (ADS)

    Cho, Myung K.; Vogiatzis, Konstantinos; Sebag, Jacques; Neill, Douglas R.

    2012-09-01

    The Large Synoptic Survey Telescope (LSST) optical design calls for a large annular 3.4 m diameter meniscus convex aspheric Secondary Mirror (M2). The M2 has a mass of approximately 1.5 metric tons and the optimized mirror support system consists of 72 axial actuators, mounted at the mirror back surface, and 6 tangent link lateral supports mounted around the outer edge. A fully integrated M2 Finite Element Model (FEM) including the mirror and the support systems has been developed to investigate the performance of the M2 assembly and to determine the image degradation due to dynamic wind loading. Detailed wind response analysis was performed based on the input from Computational Fluid Dynamics (CFD) simulations. Image quality calculations of the time history responses and Power Spectrum Density (PSD) are addressed.

  7. Adaptive secondary P30 prototype: laboratory results

    NASA Astrophysics Data System (ADS)

    Brusa, Guido; Riccardi, Armando; Ragland, Sam; Esposito, Simone; del Vecchio, Ciro; Fini, Luca; Stefanini, Paolo; Biliotti, Valdemaro; Ranfagni, Piero; Salinari, Piero; Gallieni, Daniele; Biasi, Roberto; Mantegazza, Paolo; Sciocco, G.; Noviello, G.; Invernizzi, S.

    1998-09-01

    We present the result of electrical and optical measurements performed on a reduced size adaptive secondary prototype named P30. The design of this concave deformable mirror consists of a thin deformable glass shell whose figure is controlled by electromagnetic actuators and capacitive position senors. Static measurements of the mirror optical figure, performed with a commercial interferometer, have provided the calibration of the internal position sensor. Dynamic test were performed to experimentally derive the mechanical response of the mirror to the electromagnetic actuators in order to design the mirror closed loop control law. The test, although performed on a reduced scale, are representative of the complexity and capabilities of the full size mirror. In fact, all the key-elements of the full size mirror, i.e. central supporting membrane, actuator spacing closed loop control of the device, have been implemented on the prototype.

  8. Development of the SOFIA silicon carbide secondary mirror

    NASA Astrophysics Data System (ADS)

    Fruit, Michel; Antoine, Pascal; Varin, Jean-Luc; Bittner, Hermann; Erdmann, Matthias

    2003-02-01

    The SOFIA telescope is ajoint NASA-DLR project for a 2.5 m airborne Stratospheric Observatory for IR Astronomy to be flown in a specially adapted Boeing 747 SP plane, Kayser-Threde being resopinsible for the development of the Telescope Optics. The φ 352 mm Secondary Mirror is mounted ona chopping mechanism to allow avoidance of background noise during IR observations. Stiffness associated to lightness is a major demand for such a mirror to achieve high frequency chopping. This leads to select SIlicon Carbide for the mirror blank. Its development has been run by the ASTRIUM/BOOSTEC joint venture SiCSPACE, taking full benefit of the instrinsic properties of the BOOSTEC SiC-100 sintered material, associated to qualified processes specifically developed for space borne mirrors by ASTRIUM. Achieved performances include a low mass of 1.97 kg, a very high stiffness with a first resonant frequency of 1865 Hz and a measured optical surface accuracy of 39 nm rms, using Ion Beam Figuring. It is proposed here to present the major design features of the SOFIA Secondary Mirror, highlighting the main advantages of using Silicon Carbide, the main steps of its development and the achieved optomechanical performances of the developed mirror.

  9. Thermal performance of the ATST secondary mirror

    NASA Astrophysics Data System (ADS)

    Cho, Myung K.; DeVries, Joe; Hansen, Eric

    2007-12-01

    The Advanced Technology Solar Telescope (ATST) has a 4.24m off-axis primary mirror designed to deliver diffractionlimited images of the sun. Its baseline secondary mirror (M2) design uses a 0.65m diameter Silicon Carbide mirror mounted kinematically by a bi-pod flexure mechanism at three equally spaced locations. Unlike other common telescopes, the ATST M2 is to be exposed to a significant solar heat loading. A thermal management system (TMS) will be developed to accommodate the solar loading and minimize "mirror seeing effect" by controlling the temperature difference between the M2 optical surface and the ambient air at the site. Thermo-elastic analyses for steady state thermal behaviors of the ATST secondary mirror was performed using finite element analysis by I-DEAS TM and PCRINGE TM for the optical analysis. We examined extensive heat transfer simulation cases and their results were discussed. The goal of this study is to establish thermal models by I-DEAS for an adequate thermal environment. These thermal models will be useful for estimating segment thermal responses. Current study assumes a few sample time dependent thermal loadings to synthesize the operational environment.

  10. Performance evaluations of the ATST secondary mirror

    NASA Astrophysics Data System (ADS)

    Cho, Myung K.; DeVries, Joseph; Hansen, Eric

    2007-09-01

    The Advanced Technology Solar Telescope (ATST) has a 4.24m off-axis primary mirror designed to deliver diffraction-limited images of the sun. Its baseline secondary mirror (M2) design uses a 0.65m diameter Silicon Carbide mirror mounted kinematically by a bi-pod flexure mechanism at three equally spaced locations. Unlike other common telescopes, the ATST M2 is to be exposed to a significant solar heat loading. A thermal management system will be developed to accommodate the solar loading and minimize "mirror seeing effect" by controlling the temperature difference between the M2 optical surface and the ambient air at the site. Thermo-elastic analyses for steady state thermal behaviors of the ATST secondary mirror was performed using finite element analysis by I-DEAS TM and PCFRINGE TM for the optical analysis. We examined extensive heat transfer simulation cases and their results are discussed. The goal of this study is to evaluate the optical performances of M2 using thermal models and mechanical models. Thermal responses from the models enable us to manipulate time dependent thermal loadings to synthesize the operational environment for the design and development of TMS.

  11. Testing of the Gemini secondary mirrors

    NASA Astrophysics Data System (ADS)

    Otto, Wolfgang

    1999-09-01

    The first 1-m secondary mirror for the Gemini 8-m telescopes project was delivered by Zeiss in 1998, and 2nd mirror will be delivered in the summer of 1999. For first use during commissioning we produced an extreme lightweight Zerodur solution prefabricated at Schott. To reach the 85 percent weight reduction a novel etching technique was used. INterferometric testing was done performing full aperture measurements using a concave matrix. In progress with the fabrication process of the matrix we applied 3D-mechanical measurements, IR-interferometry, and VIS-interferometry using null lenses to reach the final intrinsic quality of 6 nm rms. For interferometric testing of the secondaries phase shifting interferometry with a tunable laser diode was applied. The optical test results of the secondaries show, that the mirrors are well within specification. The finally achieved intrinsic surface quality is 17 nm rms for Unit 1 and 13 nm rms for Unit 2, dominated by cutting effects which were introduced by removing the oversize at the inner and outer edge of the mirror after the final polishing step.

  12. Large thin adaptive x-ray mirrors

    NASA Astrophysics Data System (ADS)

    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.

  13. MEMS deformable mirrors for astronomical adaptive optics

    NASA Astrophysics Data System (ADS)

    Cornelissen, S. A.; Hartzell, A. L.; Stewart, J. B.; Bifano, T. G.; Bierden, P. A.

    2010-07-01

    We report on the development of high actuator count, micro-electromechanical (MEMS) deformable mirrors designed for high order wavefront correction in ground and space-based astronomical adaptive optics instruments. The design of these polysilicon, surface-micromachined MEMS deformable mirrors builds on technology that has been used extensively to correct for ocular aberrations in retinal imaging systems and for compensation of atmospheric turbulence in free-space laser communication. These light-weight, low power deformable mirrors have an active aperture of up to 25.2mm consisting of a thin silicon membrane mirror supported by an array of 140 to 4092 electrostatic actuators which exhibit no hysteresis and have sub-nanometer repeatability making them well suited for open-loop control applications such as Multi-Object Adaptive Optics (MOAO). The continuous membrane deformable mirrors, coated with a highly reflective metal film, are capable of up to 6μm of stroke, have a surface finish of <10nm RMS with a fill factor of 99.8%. Presented in this paper are device characteristics and performance test results, as well as reliability test data and device lifetime predictions that show that trillions of actuator cycles can be achieved without failures.

  14. Optical calibration and test of the VLT Deformable Secondary Mirror

    NASA Astrophysics Data System (ADS)

    Briguglio, Runa; Xompero, Marco; Riccardi, Armando; Andrighettoni, Mario; Pescoller, Dietrich; Biasi, Roberto; Gallieni, Daniele; Vernet, Elise; Kolb, Johann; Arsenault, Robin; Madec, Pierre-Yves

    2013-12-01

    The Deformable Secondary Mirror (DSM) for the VLT (ESO) represents the state-of-art of the large-format deformable mirror technology with its 1170 voice-coil actuators and its internal metrology based on actuator co-located capacitive sensors to control the shape of the 1.12m-diameter 2mm-thick convex shell. The present paper reports the results of the optical characterization of the mirror unit with the ASSIST facility located at ESO-Garching and executed in a collaborative effort by ESO, INAF-Osservatorio Astrofisico di Arcetri and the DSM manufacturing companies (Microgate s.r.l. and A.D.S. International s.r.l.). The main purposes of the tests are the optical characterization of the shell flattening residuals, the corresponding calibration of flattening commands, the optical calibration of the capacitive sensors and the optical calibration of the mirror influence functions. The results are used for the optical acceptance of the DSM and to allow the next test phase coupling the DSM with the wave-front sensor modules of the new Adaptive Optics Facility (AOF) of ESO.

  15. Optomechanical analysis and testing of a fast steering secondary mirror prototype for the Giant Magellan Telescope

    NASA Astrophysics Data System (ADS)

    Corredor, Andrew; Park, Won Hyun; Cho, Myung; Kim, Young-Soo

    2013-09-01

    The Giant Magellan Telescope (GMT) will be one of the next class of extremely large segmented mirror telescopes. The GMT will utilize two Gregorian secondary mirrors, and Adaptive Secondary Mirror (ASM) and a Fast-steering Secondary Mirror (FSM). The FSM consists of six off-axis mirrors surrounding a central on-axis circular segment. The segments are 1.1 m in diameter and conjugated 1:1 to the seven 8.4 m segments of the primary. A prototype of the FSM mirror (FSMP) has been developed, analyzed and tested in order to demonstrate the mechanical and optical responses of the mirror assembly when subjected to structural and thermal loadings. In this paper, the mechanical and thermal performances of the FSMP were evaluated by performing finite element analyses (FEA) in NX Nastran. The deformation of the mirror's lateral flexure was measured when the FSMP was axially loaded and the temperature response of the mirror assembly was measured when exposed to a sample thermal environment. In order to validate the mirror/lateral flexure design concept, the mechanical, optical and thermal measurements obtained from the tests conducted on mirrors having two different lateral flexures were compared to the responses calculated by FEA.

  16. VLT deformable secondary mirror: integration and electromechanical tests results

    NASA Astrophysics Data System (ADS)

    Biasi, R.; Andrighettoni, M.; Angerer, G.; Mair, C.; Pescoller, D.; Lazzarini, P.; Anaclerio, E.; Mantegazza, M.; Gallieni, D.; Vernet, E.; Arsenault, R.; Madec, P.-Y.; Duhoux, P.; Riccardi, A.; Xompero, M.; Briguglio, R.; Manetti, M.; Morandini, M.

    2012-07-01

    The VLT Deformable secondary is planned to be installed on the VLT UT#4 as part of the telescope conversion into the Adaptive Optics test Facility (AOF). The adaptive unit is based on the well proven contactless, voice coil motor technology that has been already successfully implemented in the MMT, LBT and Magellan adaptive secondaries, and is considered a promising technical choice for the forthcoming ELT-generation adaptive correctors, like the E-ELT M4 and the GMT ASM. The VLT adaptive unit has been recently assembled after the completion of the manufacturing and modular test phases. In this paper, we present the most relevant aspects of the system integration and report the preliminary results of the electromechanical tests performed on the unit. This test campaign is a typical major step foreseen in all similar systems built so far: thanks to the metrology embedded in the system, that allows generating time-dependent stimuli and recording in real time the position of the controlled mirror on all actuators, typical dynamic response quality parameters like modal settling time, overshoot and following error can be acquired without employing optical measurements. In this way the system dynamic and some aspect of its thermal and long term stability can be fully characterized before starting the optical tests and calibrations.

  17. Secondary ("Plain Mirror") Testing Methods of Sir William Herschel

    NASA Astrophysics Data System (ADS)

    Albin, E. F. M.

    2004-12-01

    Although many of Sir William Herschel's telescope designs did not require a secondary mirror, he did construct Newtonian style optical systems that used "plain mirrors." A look at Herschel's own writings on the matter gives some interesting insights into the techniques of this skilled 18th - 19th century telescope maker. The author provides glimpses acquired from unpublished Herschel documents that are now in the possession of the British RAS -- these include a four volume series entitled "Experiments on the Construction of Specula," a 129 page treaty called "On the Construction of Specula," and a 179 page manuscript entitled "Results of Experiments on the Construction of Mirrors." Herschel constructed secondary mirrors for his instruments by grinding and polishing his small mirrors in a sequence that involved two tools. He tested the optical quality of a small plain mirror by utilizing two slips of white card or pasteboard. One slip was made exactly twice the length of the second. The shorter card was placed against the mirror while the longer placed at some distance away so that its reflected image exactly matched the other. The larger card was carefully placed near the eye and oriented so that it was parallel to the shorter card strip. In order to test various sections of the secondary mirror, cards of different length were used. The mirror was judged flat if the reflected image was exactly identical to the card resting on the mirror. If the mirror were concave, the reflected image would be larger (i.e., magnified) than that of the smaller slip. However, should the reflected image be lesser in size, then the mirror was convex. Figuring was done with the mirror resting above the polishing tool. A convex mirror could be made plain by lengthening the stroke while a concave mirror could be made plain by shortening the stroke.

  18. Delivery of the Second Generation VLT Secondary Mirror (M2) Unit to ESO

    NASA Astrophysics Data System (ADS)

    Arsenault, R.; Vernet, E.; Madec, P.-Y.; Lizon, J.-L.; Duhoux, P.; Conzelmann, R.; Hubin, N.; Biasi, R.; Andrighettoni, M.; Angerer, G.; Pescoller, D.; Mair, C.; Picin, F.; Gallieni, D.; Lazzarini, P.; Anaclerio, E.; Mantegazza, M.; Fumi, L.; Riccardi, A.; Briguglio, R.; Poutriquet, F.; Ruch, E.; Rinchet, A.; Carré, J.-F.; Fappani, D.

    2013-03-01

    The deformable secondary mirror (DSM), one of the key systems of the VLT Adaptive Optics Facility (AOF), has been delivered to ESO. It has been fully qualified in standalone mode and has successfully passed the technical acceptance Europe. Recently it was installed on ASSIST, the test bench for the AOF, and will undergo optical tests, which will complete its preliminary acceptance in Europe. With its 1170 actuators and 1.1-metre thin-shell mirror, it constitutes the largest adaptive optics mirror ever produced. The DSM constitutes a fine accomplishment by European industry and is set to become the "flagship" of the AOF on Paranal.

  19. Demonstration Of A Robust Composite Deformable Secondary Mirror With Low Surface Error

    NASA Astrophysics Data System (ADS)

    Ammons, Stephen; Coughenour, B.; Hart, M.; Romeo, R.; Martin, R.

    2011-01-01

    I discuss recent improvements in the development of carbon fiber reinforced polymer (CFRP) as a lightweight substrate for primary and deformable secondary mirrors on ground- and space-based telescopes. Weight reductions for ground-based primary mirrors can significantly affect cost: The weight and material cost of a large ground-based telescope go roughly as the primary mirror mass. CFRP composites provide several advantages as a substrate for thin-shell adaptive secondary mirrors as well, including high stiffness-to-weight ratio, low coefficient of thermal expansion (CTE), and robustness. We use an 8 cm prototype CFRP thin-shell deformable mirror to show that spatial CTE variation may be addressed with mounted actuators. I present measurements of surface quality at a range of temperatures characteristic of mountaintop observatories. The figure error of the Al-coated reflective surface under best actuator correction is 43 nm RMS, placing it into consideration for use in near-IR astronomy. The low surface error internal to the outer ring of actuators (17 nm RMS at 15 C and 33 nm RMS at -5 C) suggests that larger mirrors will have a similar figure quality under actuator correction on ground-based Adaptive Optics systems. Surface roughness is low (< 3 nm P-V) at a variety of temperatures. These experiments demonstrate CFRP's potential as a lightweight, robust substrate for thin-shell deformable secondary mirrors.

  20. Stewart platform kinematics and secondary mirror aberration control

    NASA Astrophysics Data System (ADS)

    Schipani, P.; Marty, L.

    2006-06-01

    This work deals with active correction of the aberrations in a telescope by moving the secondary mirror. A special attention is here dedicated to the case of a secondary mirror whose motions are controlled by a 6-6 Stewart Platform (generally called by astronomers simply "hexapod", even if this term is more general). The kinematics of the device is studied; an iterative algorithm to solve the non trivial forward kinematics problem is described.

  1. The Magellan Telescope adaptive secondary AO system

    NASA Astrophysics Data System (ADS)

    Close, Laird M.; Gasho, Victor; Kopon, Derek; Hinz, Phil M.; Hoffmann, William F.; Uomoto, Alan; Hare, Tyson

    2008-07-01

    The Magellan Clay telescope is a 6.5m Gregorian telescope located in southern Chile at Las Campanas Observatory. The Gregorian design allows for an adaptive secondary mirror that can be tested off-sky in a straight-forward manner. We have fabricated a 85 cm diameter aspheric adaptive secondary with our subcontractors and partners. This secondary has 585 actuators with <1 msec response times. The chopping adaptive secondary will allow low emissivity AO science. We will achieve very high Strehls (~98%) in the Mid-IR AO (8-26 microns) with the BLINC/MIRAC4 Mid-IR science camera. This will allow the first "super-resolution" and nulling Mid-IR studies of dusty southern objects. We will employ a high order (585 mode) pyramid wavefront sensor similar to that used in the Large Binocular Telescope AO systems. The relatively high actuator count will allow modest Strehls to be obtained in the visible (~0.8μm). Our visible light AO (Vis AO) science camera is fed by an advanced ADC and beamsplitter piggy-backed on the WFS optical table. The system science and performance requirements, and an overview the design, interface and schedule for the Magellan AO system are presented here.

  2. Design and development of a fast-steering secondary mirror for the Giant Magellan Telescope

    NASA Astrophysics Data System (ADS)

    Cho, Myung; Corredor, Andrew; Dribusch, Christoph; Park, Kwijong; Kim, Young-Soo; Moon, Il-Kweon

    2011-09-01

    The Giant Magellan Telescope (GMT) will be a 25m class telescope which is one of the extremely large telescope projects in the design and development phase. The GMT will have two Gregorian secondary mirrors, an adaptive secondary mirror (ASM) and a fast-steering secondary mirror (FSM). Both secondary mirrors are 3.2 m in diameter and built as seven 1.1 m diameter circular segments conjugated 1:1 to the seven 8.4m segments of the primary. The FSM has a tip-tilt feature to compensate image motions from the telescope structure jitters and the wind buffeting. The support system of the lightweight mirror consists of three axial actuators, one lateral support at the center, and a vacuum system. A parametric study and optimization of the FSM mirror blank and central lateral flexure design were performed. This paper reports the results of the trade study. The optical image qualities and structure functions for the axial and lateral gravity print-through cases, thermal gradient effects, and dynamic performances will be discussed for the case of a lightweighted segment with a center thickness of 140 mm weighing approximately 105 kg.

  3. An Aluminum Secondary Mirror for the SOFIA Telescope

    NASA Astrophysics Data System (ADS)

    Erickson, E. F.; Kunz, N.; Brivkalns, C. A.; Brown, T. M.; Honaker, M.

    2002-12-01

    The secondary mirror for the SOFIA telescope is made from silicon carbide. It is 352 mm in diameter, weighs 1.8 kg, and is finished to good optical tolerances. The light weight is essential for chopping with the secondary support mechanism to suppress low frequency "sky" noise. To achieve the light weight, the back side of the mirror is structured with thin-walled pockets; the face plate is 2.3 mm thick. The material is stiff, has low density and high thermal conductance, but is brittle. The latter is a concern because failure of this mirror would render the telescope inoperable. For this reason we are designing a spare secondary mirror. The spare must match the mass and moments of inertia of the SiC mirror (to permit effective chopping), but should be more robust and much cheaper. The spare should permit continuation of much of the observing program, and since many of SOFIA's observations will be made in the far-infrared, the optical quality of the spare can be significantly lower than that of the SiC secondary. Currently it appears that a bare aluminum secondary can be made to meet the requirements, while achieving a diffraction-limited wavelength of 20 microns or less. The design details will be described and discussed in the paper. We gratefully acknowledge NASA support of this work.

  4. Design and preliminary tests of the VLT secondary mirror unit

    NASA Astrophysics Data System (ADS)

    Stanghellini, Stefano; Manil, Emmanuel; Schmid, M.; Dost, K. H.

    1997-03-01

    The mechanics of the secondary unit are located behind the secondary mirror as seen from the telescope focus. The secondary is undersized and defines the pupil of the telescope. There is a focusing and centering drive for slow adjustments of the secondary mirror. In addition, the secondary mirror has a fast beam steering mechanism for chopping and rapid guiding to remove atmospheric wavefront tilt during observations. The specified square wave chopping frequency is 5 Hz with a duty cycle larger than 80%. To achieve a high bandwidth, the secondary mirror is manufactured of light-weighted beryllium coated with nickel. The beam steering mechanism has a counter-vibrating mass to compensate for dynamic forces and moments. The chopping mechanism has been successfully tested. The code of the digital control used during the tests was generated using Matlab real time toolbox. The servos were implemented on a digital signal processor card equipped with a TMS 320C40. To compensate for resonances inside the bandwidth of the servos, a special filter is applied in the velocity loop. The design of the secondary unit is now completed and fabrication and assembly have begun.

  5. Novel unimorph adaptive mirrors for astronomy applications

    NASA Astrophysics Data System (ADS)

    Rausch, Peter; Verpoort, Sven; Wittrock, Ulrich

    2012-07-01

    We have developed a new type of unimorph deformable mirror for the correction of low-order Zernike modes. The mirror features a clear aperture of 50 mm combined with large peak-to-valley amplitudes of up to 35 μm. Newly developed fabrication processes allow the use of prefabricated, coated, super-polished glass substrates. The mirror's unique features suggest the use in several astronomical applications like the compensation of atmospheric aberrations seen by laser beacons and the use in woofer-tweeter systems. Additionally, the design enables an efficient correction of the inevitable wave-front error imposed by the floppy structure of primary mirrors in future large space telescopes. We have modeled the mirror by using analytical as well as finite element models. We will present design, key features and manufacturing steps of the deformable mirror.

  6. Prototype Secondary Mirror Assembly For The Space Infrared Telescope Facility

    NASA Astrophysics Data System (ADS)

    Stier, M.; Duffy, M.; Gullapalli, S.; Rockwell, R.; Sileo, F.; Krim, M.

    1988-04-01

    We describe our concept for a liquid helium temperature prototype secondary mirror assembly (PSMA) for the Space Infrared Telescope Facility. SIRTF, a NASA "Great Observatory" to be launched in the 1990's, is a superfluid heliumcooled 1-meter class telescope with much more stringent performance requirements than its precursor the Infrared Astronomical Satellite (IRAS). The SIRTF secondary mirror assembly must operate near 4 K and provide the functions of 2-axis dynamic tilting ("chopping") in addition to the conventional functions of focus and centering. The PSMA must be able to withstand random vibration testing and provide all of the functions needed by the SIRTF observatory. Our PSMA concept employs a fused quartz mirror kinematically attached at its center to an aluminum cruciform. The mirror/cruciform assembly is driven in tilt about its combined center of mass using a unique flexure pivot and a four-actuator control system with feed-back provided by pairs of eddy current position sensors. The actuators are mounted on a second flexure-pivoted mass providing angular momentum compensation and isolating the telescope from vibration-induced disturbances. The mirror/cruciform and the reaction mass are attached to opposite sides of an aluminum mounting plate whose AL/L characteristics are nominally identical to that of the aluminum flexure pivot material. The mounting plate is connected to the outer housing by a focus and centering mechanism based upon the six degree of freedom secondary mirror assembly developed for the Hubble Space Telescope.

  7. HCN laser with an adaptive output mirror

    SciTech Connect

    Kamenev, Yu E; Masalov, S A; Filimonova, A A

    2006-09-30

    A device for optimal coupling between a laser resonator and the external medium, having the form of one-dimensional wire grating conjugated with a plane mirror with an aperture, is proposed, developed and tested experimentally. The dependences of the output laser power on the separation between the grating and the mirror, diameter of the aperture in the plane mirror, and the grating period, are studied. The obtained results not only confirm the possibility of using such a coupling device, but also point towards the ways and principles of its application. (lasers)

  8. Space Adaptation of Active Mirror Segment Concepts

    NASA Technical Reports Server (NTRS)

    Ames, Gregory H.

    1999-01-01

    This report summarizes the results of a three year effort by Blue Line Engineering Co. to advance the state of segmented mirror systems in several separate but related areas. The initial set of tasks were designed to address the issues of system level architecture, digital processing system, cluster level support structures, and advanced mirror fabrication concepts. Later in the project new tasks were added to provide support to the existing segmented mirror testbed at Marshall Space Flight Center (MSFC) in the form of upgrades to the 36 subaperture wavefront sensor. Still later, tasks were added to build and install a new system processor based on the results of the new system architecture. The project was successful in achieving a number of important results. These include the following most notable accomplishments: 1) The creation of a new modular digital processing system that is extremely capable and may be applied to a wide range of segmented mirror systems as well as many classes of Multiple Input Multiple Output (MIMO) control systems such as active structures or industrial automation. 2) A new graphical user interface was created for operation of segmented mirror systems. 3) The development of a high bit rate serial data loop that permits bi-directional flow of data to and from as many as 39 segments daisy-chained to form a single cluster of segments. 4) Upgrade of the 36 subaperture Hartmann type Wave Front Sensor (WFS) of the Phased Array Mirror, Extendible Large Aperture (PAMELA) testbed at MSFC resulting in a 40 to 5OX improvement in SNR which in turn enabled NASA personnel to achieve many significant strides in improved closed-loop system operation in 1998. 5) A new system level processor was built and delivered to MSFC for use with the PAMELA testbed. This new system featured a new graphical user interface to replace the obsolete and non-supported menu system originally delivered with the PAMELA system. The hardware featured Blue Line's new stackable

  9. Optimal wavefront control for adaptive segmented mirrors

    NASA Technical Reports Server (NTRS)

    Downie, John D.; Goodman, Joseph W.

    1989-01-01

    A ground-based astronomical telescope with a segmented primary mirror will suffer image-degrading wavefront aberrations from at least two sources: (1) atmospheric turbulence and (2) segment misalignment or figure errors of the mirror itself. This paper describes the derivation of a mirror control feedback matrix that assumes the presence of both types of aberration and is optimum in the sense that it minimizes the mean-squared residual wavefront error. Assumptions of the statistical nature of the wavefront measurement errors, atmospheric phase aberrations, and segment misalignment errors are made in the process of derivation. Examples of the degree of correlation are presented for three different types of wavefront measurement data and compared to results of simple corrections.

  10. Active optics control of VST telescope secondary mirror.

    PubMed

    Schipani, Pietro; D'Orsi, Sergio; Fierro, Davide; Marty, Laurent

    2010-06-01

    In telescopes based on active optics, defocus and coma are usually compensated for by secondary mirror movements. They are performed at the Very Large Telescope Survey Telescope (VST) with a hexapod--a parallel robot with six degrees of freedom positioning capability. We describe the application of the two-mirror telescope theory to the VST case and the solutions adopted for the hexapod control. We present the results of performance and reliability tests performed both in the laboratory and at the telescope. PMID:20517391

  11. Fabrication Methods for Adaptive Deformable Mirrors

    NASA Technical Reports Server (NTRS)

    Toda, Risaku; White, Victor E.; Manohara, Harish; Patterson, Keith D.; Yamamoto, Namiko; Gdoutos, Eleftherios; Steeves, John B.; Daraio, Chiara; Pellegrino, Sergio

    2013-01-01

    Previously, it was difficult to fabricate deformable mirrors made by piezoelectric actuators. This is because numerous actuators need to be precisely assembled to control the surface shape of the mirror. Two approaches have been developed. Both approaches begin by depositing a stack of piezoelectric films and electrodes over a silicon wafer substrate. In the first approach, the silicon wafer is removed initially by plasmabased reactive ion etching (RIE), and non-plasma dry etching with xenon difluoride (XeF2). In the second approach, the actuator film stack is immersed in a liquid such as deionized water. The adhesion between the actuator film stack and the substrate is relatively weak. Simply by seeping liquid between the film and the substrate, the actuator film stack is gently released from the substrate. The deformable mirror contains multiple piezoelectric membrane layers as well as multiple electrode layers (some are patterned and some are unpatterned). At the piezolectric layer, polyvinylidene fluoride (PVDF), or its co-polymer, poly(vinylidene fluoride trifluoroethylene P(VDF-TrFE) is used. The surface of the mirror is coated with a reflective coating. The actuator film stack is fabricated on silicon, or silicon on insulator (SOI) substrate, by repeatedly spin-coating the PVDF or P(VDFTrFE) solution and patterned metal (electrode) deposition. In the first approach, the actuator film stack is prepared on SOI substrate. Then, the thick silicon (typically 500-micron thick and called handle silicon) of the SOI wafer is etched by a deep reactive ion etching process tool (SF6-based plasma etching). This deep RIE stops at the middle SiO2 layer. The middle SiO2 layer is etched by either HF-based wet etching or dry plasma etch. The thin silicon layer (generally called a device layer) of SOI is removed by XeF2 dry etch. This XeF2 etch is very gentle and extremely selective, so the released mirror membrane is not damaged. It is possible to replace SOI with silicon

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

    NASA Astrophysics Data System (ADS)

    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.

  13. A nickel-carbon-fibre composite for large adaptive mirrors: fabrication methods and properties.

    PubMed

    Thompson, S J; Brooks, D; Doel, A P

    2008-01-21

    We present results from our recent research into carbon-fibre composite (CFC) mirror fabrication for optical and infra-red applications. In particular this research is aimed towards the next generation of extremely large telescopes to offer an alternative to thin glass shell adaptive secondary mirrors. We address the issues involved with CFC mirror production, in particular the accuracy of the form replication process, a suitable surface for polishing to optical quality, no fibre print-through, environmental stability (shape change due to thermal and moisture variations), material uniformity and lifetime. We have performed experiments into the effectiveness of cold electroplating thick nickel coatings to totally encapsulate the CFC base substrate; the manufacturing procedure and properties of the Ni-CFC mirror are described here. PMID:18542204

  14. Ferrofluid based deformable mirrors: a new approach to adaptive optics using liquid mirrors

    NASA Astrophysics Data System (ADS)

    Laird, Phil R.; Bergamasco, R.; Bérubé, Vincent; Borra, Ermanno F.; Gingras, Julie; Ritcey, Anna-Marie R.; Rioux, Myriam; Robitaille, Nathalie; Thibault, Simon; Vieira da Silva, L., Jr.; Yockell-Lelièvre, Helene

    2003-02-01

    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.

  15. Adaptive optics ophthalmologic systems using dual deformable mirrors

    SciTech Connect

    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.

  16. Modeling and simulation of a 6-DOF parallel platform for telescope secondary mirror

    NASA Astrophysics Data System (ADS)

    Yue, Zhongyu; Ye, Yu; Gu, Bozhong

    2014-07-01

    The 6-DOF parallel platform in this paper is a kind of Stewart platform. It can be used as supporting structure for telescope secondary mirror. In order to adapt the special dynamic environment of the telescope secondary mirror and to be installed in extremely narrow space, a unique parallel platform is designed. PSS Stewart platform and SPS Stewart platform are analyzed and compared. Then the PSS Stewart platform is chosen for detailed design. The virtual prototyping model of the parallel platform is built. The model is used for the analysis and calculation of multi-body dynamics. With the help of ANSYS, the finite element model of the platform is built and then the analysis is performed. According to the above analysis the experimental prototype of the platform is built.

  17. LBT adaptive secondary units final design and construction

    NASA Astrophysics Data System (ADS)

    Gallieni, Daniele; Anaclerio, Enzo; Lazzarini, Paolo G.; Ripamonti, Angelo; Spairani, Roberto; Del Vecchio, Ciro; Salinari, Piero; Riccardi, Armando; Stefanini, Paolo; Biasi, Roberto

    2003-02-01

    The Large Binocular Telescope will perform its first level AO correction at visual wavelengths by the two Gregorian secondary mirrors. Each unit is made by a 911 mm diameter and 1.6 mm thick Zerodur shell which shape is controlled by 672 electromagnetic actuators at 1 kHz rate. The shape of each mirror is referred to a Zerodur 50 mm thick backplate through a set of capacitive sensors co-located with the actuators. Each adaptive secondary unit embeds its real time computer for actuator control and communication. Each unit is aligned into the secondary hub by a 6 d.o.f. hexapod system. The construction of the AO units started this year, while the hexapods have been completed in 2001. We present in this paper the final design of the adaptive secondary systems with particular emphasis on the modifications that we made based on the MMT adaptive secondary experience. We will also report the first results of the subsystems development tests.

  18. Mirror contamination and secondary electron effects during EUV reflectivity analysis

    NASA Astrophysics Data System (ADS)

    Catalfano, M.; Kanjilal, A.; Al-Ajlony, A.; Harilal, S. S.; Hassanein, A.; Rice, B.

    2012-03-01

    We investigated Ru mirror contamination and subsequent EUV reflectivity loss using the IMPACT facility at Purdue University. Because Ru can either be used as a grazing mirror or as a capping layer for multilayer normal mirror, we examined the angular dependency of XPS peak area intensity at the O 1s and Ru 3d regions as well as the effects of sputtering. Although no change in intensity has been observed at lower take-off angles from the target surface, the peak area intensity starts changing with increasing θ (i.e., emission observation angle, representing the angle between the target surface plane and detector entrance). Among different components, the effect of water and oxidized carbon are found to be most notable when viewed at lower θ, and primarily responsible for degrading the reflectivity of the Ru layer. On the other hand, the effect of OH becomes dominant with increasing observation angle θ, and thus plays a key role to suppress optical transmission. Moreover, atomic carbon effect is found to peak when observed at 30°, and most likely plays an important role in degrading both reflectivity and transmission. This is also because of the total photon path length in the Ru film at different angles. During the contamination process, the EUV reflectivity of the Ru film is found to significantly degrade in the presence of additional secondary electrons from the focusing Ru mirror of the EUV setup. This effect could be explained in the light of a competition between oxidation and carbonization processes on Ru surface.

  19. Polymer-based micro deformable mirror for adaptive optics applications

    NASA Astrophysics Data System (ADS)

    Zamkotsian, Frederic; Conedera, Veronique; Liotard, Arnaud; Schroeder, Andreas; Fabre, Norbert; Camon, Henri; Lanzoni, Patrick

    2005-01-01

    Next generation giant telescopes as well as next generation instrumentation for 10m-class telescopes relies on the availability of highly performing adaptive optical systems, for studying new fields like circumstellar disks and extrasolar planets. These systems require deformable mirrors with very challenging parameters, including number of actuators up to 250 000 and inter-actuator spacing around 500μm. MOEMS-based devices are promising for future deformable mirrors. However, only limited strokes for large driving voltages have been demonstrated. In order to overcome these limitations, we are currently developing a micro-deformable mirror based on an array of electrostatic actuators with attachment posts to a continuous mirror on top. The originality of our approach lies in the elaboration of a sacrificial layer and of a structural layer made of polymer materials, using low-temperature process. This process allows the realization of high optical quality mirrors on top of an actuator array made with various techniques. We have developed the first polymer piston-motion actuator in order to reach high strokes for low driving voltages: a 10μm thick mobile plate with four springs attached to the substrate, and with an air gap of 10μm exhibits a piston motion of 2μm for 30V. Preliminary comparison with FEM models show very good agreement and design of a complete polymer-based MDM looks possible.

  20. Unconventional adaptive mirrors at the University of Arizona

    NASA Astrophysics Data System (ADS)

    Hart, Michael; Ammons, S. Mark; Coughenour, Blake; Romeo, Robert

    2012-06-01

    We describe the construction and application of innovative deformable mirrors for adaptive optics (AO) being developed at the University of Arizona's Center for Astronomical Adaptive Optics. The mirrors are up to 1 m in diameter, with high actuator stroke, and are optically powered. Scientific motivations for the work include the detection of earthlike planets around other nearby stars, as well as non-astronomical applications such as directed energy and horizontal imaging for defense and security. We describe how high resolution imaging is delivered over an unusually wide field of view by ground-layer AO. This technique employs multiple laser guide stars to sense the instantaneous three-dimensional distribution of atmospheric turbulence. Imaging with high signal-to-noise ratio in the thermal infrared is enabled by embedding the deformable mirror directly in the telescope. We also describe recent work to develop a new generation of these mirrors with lighter weight and improved robustness by use of replicated composite materials which shows promise for greatly reducing the cost of AO and broadening its appeal, particularly for non-astronomical applications as well as for a new generation of extremely large ground-based telescopes of 30 m diameter now under construction.

  1. An approach to fabrication of large adaptive optics mirrors

    NASA Astrophysics Data System (ADS)

    Schwartz, Eric; Rey, Justin; Blaszak, David; Cavaco, Jeffrey

    2014-07-01

    For more than two decades, Northrop Grumman Xinetics has been the principal supplier of small deformable mirrors that enable adaptive optical (AO) systems for the ground-based astronomical telescope community. With today's drive toward extremely large aperture systems, and the desire of telescope designers to include adaptive optics in the main optical path of the telescope, Xinetics has recognized the need for large active mirrors with the requisite bandwidth and actuator stoke. Presented in this paper is the proposed use of Northrop Grumman Xinetics' large, ultra-lightweight Silicon Carbide substrates with surface parallel actuation of sufficient spatial density and bandwidth to meet the requirements of tomorrow's AO systems, while reducing complexity and cost.

  2. Modeling for deformable mirrors and the adaptive optics optimization program

    SciTech Connect

    Henesian, M.A.; Haney, S.W.; Trenholme, J.B.; Thomas, M.

    1997-03-18

    We discuss aspects of adaptive optics optimization for large fusion laser systems such as the 192-arm National Ignition Facility (NIF) at LLNL. By way of example, we considered the discrete actuator deformable mirror and Hartmann sensor system used on the Beamlet laser. Beamlet is a single-aperture prototype of the 11-0-5 slab amplifier design for NIF, and so we expect similar optical distortion levels and deformable mirror correction requirements. We are now in the process of developing a numerically efficient object oriented C++ language implementation of our adaptive optics and wavefront sensor code, but this code is not yet operational. Results are based instead on the prototype algorithms, coded-up in an interpreted array processing computer language.

  3. Research and design for focusing device of secondary mirror

    NASA Astrophysics Data System (ADS)

    Li, WeiYan; Zhang, DanDan; Lv, QunBo; Liu, YangYang; Pei, LinLin; Wang, JianWei

    2015-09-01

    The position of optical plane for a space remote sensing instrument will be changed in severe launching process and complex working thermal environments, which affects the imaging quality of the remote sensing instrument seriously. based on traditional R-C optical systems designed a new type of initiative thermal controlling focusing device, which was driver by the change of thermal according to the basic concepts of thermal expansion properties, the apparatus selectively adjusting the position of the secondary mirror to compensate for the amount of defocus, analysis the main factors of affecting the accuracy of focusing device, and using finite element analysis software for simulation data, while the device for the corresponding experimental verification according to the actual working environment .The results showed that the focusing device designed to meet the required shaking volume requirement 15."

  4. Design and analysis of supporting structure between the primary mirror and the secondary mirror on a space telescope

    NASA Astrophysics Data System (ADS)

    Wang, Chenjie; Chai, Wenyi; Feng, Liangjie; Yang, Wengang; Wang, Wei; Fan, Xuewu

    2015-10-01

    Mechanical stability is a significant segment for an on-axis space telescope to assure its assembly accuracy as well as the image quality in the rigorous space environment, supporting structure between the primary mirror and the secondary mirror as a main structure of the on-axis space telescope must be designed reasonably to meet the mission requirements of the space telescope. Meanwhile, in view of the limitation of the satellite launching cost, it is necessary to reduce the weight and power compensation during the supporting structure design based on the satisfaction of telescope performance. Two types of supporting structure for a space telescope are designed, one is three-tripod structure which has three tripods located on the optical bench to support the secondary mirror assemblies and keep the distance between the primary mirror and the secondary mirror, the other is barrel supporting structure which includes a tube and a secondary mirror support with four spider struts. To compare the mechanical performance and launching cost of the two kinds of supporting structure, both structural and thermal analysis model are established. The analysis results indicates that the three-tripod support is lighter, has better mechanical performance and needs less power compensation than the barrel support.

  5. The deformable secondary mirror of VLT: final electro-mechanical and optical acceptance test results

    NASA Astrophysics Data System (ADS)

    Briguglio, Runa; Biasi, Roberto; Xompero, Marco; Riccardi, Armando; Andrighettoni, Mario; Pescoller, Dietrich; Angerer, Gerald; Gallieni, Daniele; Vernet, Elise; Kolb, Johann; Arsenault, Robin; Madec, Pierre-Yves

    2014-07-01

    The Deformable Secondary Mirror (DSM) for the VLT ended the stand-alone electro-mechanical and optical acceptance process, entering the test phase as part of the Adaptive Optics Facility (AOF) at the ESO Headquarter (Garching). The VLT-DSM currently represents the most advanced already-built large-format deformable mirror with its 1170 voice-coil actuators and its internal metrology based on co-located capacitive sensors to control the shape of the 1.12m-diameter 2mm-thick convex shell. The present paper reports the final results of the electro-mechanical and optical characterization of the DSM executed in a collaborative effort by the DSM manufacturing companies (Microgate s.r.l. and A.D.S. International s.r.l.), INAF-Osservatorio Astrofisico di Arcetri and ESO. The electro-mechanical acceptance tests have been performed in the company premises and their main purpose was the dynamical characterization of the internal control loop response and the calibration of the system data that are needed for its optimization. The optical acceptance tests have been performed at ESO (Garching) using the ASSIST optical test facility. The main purpose of the tests are the characterization of the optical shell flattening residuals, the corresponding calibration of flattening commands, the optical calibration of the capacitive sensors and the optical calibration of the mirror influence functions.

  6. Polymer-based micro-deformable mirror for adaptive optics

    NASA Astrophysics Data System (ADS)

    Liotard, Arnaud; Zamkotsian, Frederic; Conedera, Veronique; Fabre, Norbert; Lanzoni, Patrick; Camon, Henri; Chazallet, Frederic

    2006-01-01

    Highly performing adaptive optical (AO) systems are mandatory for next generation giant telescopes as well as next generation instrumentation for 10m-class telescopes, for studying new fields like circumstellar disks and extra-solar planets. These systems require deformable mirrors with very challenging parameters, including number of actuators up to 250 000 and inter-actuator spacing around 500μm. MOEMS-based devices are promising for future deformable mirrors. We are currently developing a micro-deformable mirror (MDM) based on an array of electrostatic actuators with attachment posts to a continuous mirror on top. In order to reach large stroke for low driving voltage, the originality of our approach lies in the elaboration of a sacrificial layer and of a structural layer made of polymer materials. We have developed the first polymer piston-motion actuator: a 10μm thick mobile plate with four springs attached to the substrate, and with an air gap of 10μm exhibits a piston motion of 2μm for 30V, and measured resonance frequency of 6.5kHz is well suited for AO systems. The electrostatic force provides a non-linear actuation, while AO systems are based on linear matrices operations. We have successfully developed a dedicated 14-bit electronics in order to "linearize" the actuation. Actual location of the actuator versus expected location of the actuator is obtained with a standard deviation of 21 nm. Comparison with FEM models shows very good agreement, and design of a complete polymer-based MDM has been done.

  7. The Magellan Telescope Deformable Secondary Adaptive Optics System

    NASA Astrophysics Data System (ADS)

    Close, Laird M.; Gasho, V.; Kopon, D.; Males, J.; Hinz, P.; Hare, T.

    2009-05-01

    We present the adaptive optics system for the 6.5m Magellan Telescope. The Magellan telescope is a 6.5m Gregorian telescope located in southern Chile at Las Campanas Observatory. The Gregorian design allows for an adaptive secondary mirror that can be tested off-sky in a straight-forward manner. We have fabricated a 85 cm diameter aspheric adaptive secondary with our subcontractors and partners. This secondary has 585 actuators with 1 msec response times. The secondary will allow low emissivity AO science. We will achieve very high Strehls ( 98%) in the Mid-IR (8-26 microns) imaged with the BLINC/MIRAC4 Mid-IR camera. This will allow the first "super-resolution" Mid-IR studies of dusty southern objects. We will employ a high order (585 mode) pyramid wavefront sensor similar to that used in the Large Binocular Telescope AO systems. The relatively high actuator count for a 6.5m telescope will allow modest Strehls to be obtained in the visible. Our visible light AO CCD camera is fed by a beamsplitter piggy backed on the wavefront sensor system. We have addressed several difficult issues with 20 milliarcsec diffraction-limited imaging in the visible with our VisAO system. The Magellan AO system successfully passed PDR in December 2008 and should have first light in early 2011.

  8. EELV Secondary Payload Adapter (ESPA)

    NASA Astrophysics Data System (ADS)

    Haskett, Scott A.; Weis, Steven C.; Doggrell, Leslie J.; Sciulli, Dino; Meink, Troy E.; Ganley, Jeff T.; Maly, Joseph R.; Jurisson, Karl

    2000-11-01

    Despite growing international interest in small satellites, high dedicated expendable launch vehicle costs and the lack of secondary launch opportunities continue to hinder the full exploitation of small satellite technology. In the United States, the Department of Defense (DoD), NASA, other government agencies, commercial companies, and many universities use small satellites to perform space experiments, demonstrate new technology, and test operational prototype hardware. In addition, the DoD continues to study the role of small satellites in fulfilling operational mission requirements. However, the US lacks sufficient small satellite launch capacity. Furthermore, US government agencies are restricted to the use of US launch vehicles, which eliminates many affordable launch opportunities. In an effort to increase the number of space experiments that can be flown with a small, fixed budget, the DoD Space Test Program (STP) has teamed with the Air Force Research Laboratory Space Vehicles Directorate (AFRL/VS) to develop a low-cost solution for the small satellite launch program. Our solution, which can be implemented on both Boeing and Lockheed-Martin Evolved Expendable Launch Vehicle-Medium (EELV-M) boosters, is called the EELV Secondary Payload Adaptor (ESPA). ESPA will increase the number of launch opportunities for 180kg-class (or smaller) satellites at prices highly competitive with other secondary launch services worldwide.

  9. Contactless thin adaptive mirror technology: past, present, and future

    NASA Astrophysics Data System (ADS)

    Biasi, Roberto; Gallieni, Daniele; Salinari, Piero; Riccardi, Armando; Mantegazza, Paolo

    2010-07-01

    The contactless, voice coil motor adaptive mirror technology starts from an idea by Piero Salinari in 1993. This idea has progressively evolved to real systems thanks to a fruitful collaboration involving Italian research institutes (INAF - Osservatorio Astrofisico di Arcetri and Aerospace Department of Politecnico di Milano) and small Italian enterprises (Microgate and ADS). Collaboration between research institutions and industry is still very effectively in place, but nowadays the technology has left the initial R&D phase reaching a stage in which the whole projects are managed by the industrial entities. In this paper we present the baseline concept and its evolution, describing the main progress milestones. These are paced by the actual implementation of this idea into real systems, from MMT, to LBT, Magellan, VLT, GMT and E-ELT. The fundamental concept and layout has remained unchanged through this evolution, maintaining its intrinsic advantages: tolerance to actuators' failures, mechanical de-coupling and relaxed tolerances between correcting mirror and reference structure, large stroke, hysteresis-free behavior. Moreover, this concept has proved its expandability to very large systems with thousands of controlled d.o.f. Notwithstanding the solidity of the fundamentals, the implementation has strongly evolved from the beginning, in order to deal with the dimensional, power, maintainability and reliability constraints imposed by the increased size of the targeted systems.

  10. Optimal mirror deformation for multi conjugate adaptive optics systems

    NASA Astrophysics Data System (ADS)

    Raffetseder, S.; Ramlau, R.; Yudytskiy, M.

    2016-02-01

    Multi conjugate adaptive optics (MCAO) is a system planned for all future extremely large telescopes to compensate in real-time for the optical distortions caused by atmospheric turbulence over a wide field of view. The principles of MCAO are based on two inverse problems: a stable tomographic reconstruction of the turbulence profile followed by the optimal alignment of multiple deformable mirrors (DMs), conjugated to different altitudes in the atmosphere. We present a novel method to treat the optimal mirror deformation problem for MCAO. Contrary to the standard approach where the problem is formulated over a discrete set of optimization directions we focus on the solution of the continuous optimization problem. In the paper we study the existence and uniqueness of the solution and present a Tikhonov based regularization method. This approach gives us the flexibility to apply quadrature rules for a more sophisticated discretization scheme. Using numerical simulations in the context of the European extremely large telescope we show that our method leads to a significant improvement in the reconstruction quality over the standard approach and allows to reduce the numerical burden on the computer performing the computations.

  11. Status of the secondary mirrors (M2) for the Gemini 8-m telescopes

    NASA Astrophysics Data System (ADS)

    Knohl, Ernst-Dieter; Schoeppach, Armin; Pickering, Michael A.

    1998-08-01

    The 1-m diameter lightweight secondary mirrors (M2) for the Gemini 8-m telescopes will be the largest CVD-SiC mirrors ever produced. The design and manufacture of these mirrors is a very challenging task. In this paper we will discuss the mirror design, structural and mechanical analysis, and the CVD manufacturing process used to produce the mirror blanks. The lightweight design consist of a thin faceplate (4-mm) and triangular backstructure cells with ribs of varying heights. The main drivers in the design were weight (40 kg) and manufacturing limitations imposed on the backstructure cells and mirror mounts. Finite element modeling predicts that the mirror design will meet all of the Gemini M2 requirements for weight, mechanical integrity, resonances, and optical performance. Special design considerations were necessary to avoid stress concentration in the mounting areas and to meet the requirement that the mirror survive an 8-g earthquake. The highest risk step in the mirror blank manufacturing process is the near-net-shape CVD deposition of the thin, curved faceplate. Special tooling and procedures had to be developed to produce faceplates free of fractures, cracks, and stress during the cool-down from deposition temperature (1350 C) to room temperature. Due to time delay with the CVD manufacturing process in the meantime a backup solution from Zerodur has been started. This mirror is now in the advanced polishing process. Because the design of both mirrors is very similar an excellent comparison of both solutions is possible.

  12. Hubble Space Telescope secondary mirror vertex radius/conic constant test

    NASA Technical Reports Server (NTRS)

    Parks, Robert

    1991-01-01

    The Hubble Space Telescope backup secondary mirror was tested to determine the vertex radius and conic constant. Three completely independent tests (to the same procedure) were performed. Similar measurements in the three tests were highly consistent. The values obtained for the vertex radius and conic constant were the nominal design values within the error bars associated with the tests. Visual examination of the interferometric data did not show any measurable zonal figure error in the secondary mirror.

  13. A conceptual design study for the secondary mirror drive of the shuttle infrared telescope facility (SIRTF)

    NASA Technical Reports Server (NTRS)

    Sager, R. E.; Cox, D. W.

    1983-01-01

    Various conceptual designs for the secondary mirror actuator system to be used in the Shuttle Infrared Telescope Facility (SIRTF) were evaluated. In addition, a set of design concepts was developed to assist in the solution of problems crucial for optimum performance of the secondary mirror actuator system. A specific conceptual approach was presented along with a plan for developing that approach and identifying issues of critical importance in the developmental effort.

  14. New phase compensating secondary mirrors for the NASA Infrared Telescope Facility

    NASA Astrophysics Data System (ADS)

    Tollestrup, Eric V.; Tokunaga, Alan T.

    2010-07-01

    The NASA Infrared Telescope Facility is engaged in a long-term program to improve the image quality of the telescope. One element of the program is to minimize the static aberrations. The largest static aberration is spherical aberration, although aberrations caused by zonal polishing rings and support-pad print-through on the primary mirror are also significant. To correct these static wave front errors, a new secondary mirror is being fabricated with a custom, phase compensating surface. Since the as-built optical specifications for the IRTF mirrors have been lost, a configurable multimode instrument was fabricated for use at both the prime and Cassegrain foci to characterize the primary mirror and to measure the wave front errors at both foci. The instrument modes include a focal plane camera, a knife-edge tester, a pupil viewer, a Hartmann wave front sensor, a calibrator, and an on-axis guider. Test results from the prime focus show that the primary mirror has an incorrect conic surface and is poorly supported, which results in a fixed amount of spherical aberration and variable amounts of astigmatism, coma, and trefoil. Cassegrain focal plane results show that the original secondary mirror mount system also induces aberrations. Two new secondary mirrors have been made and at least one of the mirrors will have a custom surface, using ion beam polishing methods, to correct these static aberrations. An analysis is presently underway to determine the optimum compensating surface to be applied by ion beam polishing.

  15. Adaptive aberration correction using a triode hyperbolic electron mirror.

    PubMed

    Fitzgerald, J P S; Word, R C; Könenkamp, R

    2011-01-01

    A converging electron mirror can be used to compensate spherical and chromatic aberrations in an electron microscope. This paper presents an analytical solution to a novel triode (three electrode) hyperbolic mirror as an improvement to the well-known diode (two electrode) hyperbolic mirror for aberration correction. A weakness of the diode mirror is a lack of flexibility in changing the chromatic and spherical aberration coefficients independently without changes in the mirror geometry. In order to remove this limitation, a third electrode can be added. We calculate the optical properties of the resulting triode mirror analytically on the basis of a simple model field distribution. We present the optical properties-the object/image distance, z(0), and the coefficients of spherical and chromatic aberration, C(s) and C(c), of both mirror types from an analysis of electron trajectories in the mirror field. From this analysis, we demonstrate that while the properties of both designs are similar, the additional parameters in the triode mirror improve the range of aberration that can be corrected. The triode mirror is also able to provide a dynamic adjustment range of chromatic aberration for fixed spherical aberration and focal length, or any permutation of these three parameters. While the dynamic range depends on the values of aberration correction needed, a nominal 10% tuning range is possible for most configurations accompanied by less than 1% change in the other two properties. PMID:21930022

  16. Silver coating of the 1.3 m infrared secondary mirror of Subaru.

    NASA Astrophysics Data System (ADS)

    Kanzawa, T.; Sasaki, G.; Yutani, M.; Torii, Y.; Ohshima, N.; Kamata, Y.; Hayashi, S. S.; Nakagiri, M.; Imi, K.; Noguchi, T.

    1999-09-01

    The authors report the silver coating of 1266 mm secondary mirror to be used for infrared observations at Subaru Telescope. Silver was deposited over the chromium bondage layer, using a 1.6-m vacuum coating chamber at the Advanced Technology Center of the National Astronomical Observatory of Japan. The witness mirrors coated at the same time with this mirror show the characteristics as follows: 1) Total thickness of the chromium plus silver film is 1300±100 Å. 2) Reflectivity is 98±1% over the wide range of visible wavelength to the near infrared wavelength.

  17. Static and Dynamic Responses of AN Adaptive Optics Ferrofluidic Mirror - Poster Paper

    NASA Astrophysics Data System (ADS)

    Seaman, A.; Cookson, C. J.; MacPherson, J. B.; Borra, E. F.; Ritcey, A. M.; Asselin, D.; Jerominek, H.; Thibault, S.; Campbell, M. C. W.

    2008-01-01

    Ferrofluidic mirrors can be used to improve images of structures at the rear of the eye and may be an effective, low cost solution for adaptive optics, perhaps allowing it to become widespread in clinical settings. We use a Hartmann-Shack wavefront reconstruction technique to study the static and dynamic responses of a ferrofluidic mirror. The displacement heights versus the current in the magnetic field actuators of the mirror have been measured, as well as actuator influence functions (including non-linearites). Finally, we also characterized the real-time dynamics of the mirror.

  18. High-resolution adaptive optics scanning laser ophthalmoscope with multiple deformable mirrors

    DOEpatents

    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.

  19. Modelling MEMS deformable mirrors for astronomical adaptive optics

    NASA Astrophysics Data System (ADS)

    Blain, Celia

    As of July 2012, 777 exoplanets have been discovered utilizing mainly indirect detection techniques. The direct imaging of exoplanets is the next goal for astronomers, because it will reveal the diversity of planets and planetary systems, and will give access to the exoplanet's chemical composition via spectroscopy. With this spectroscopic knowledge, astronomers will be able to know, if a planet is terrestrial and, possibly, even find evidence of life. With so much potential, this branch of astronomy has also captivated the general public attention. The direct imaging of exoplanets remains a challenging task, due to (i) the extremely high contrast between the parent star and the orbiting exoplanet and (ii) their small angular separation. For ground-based observatories, this task is made even more difficult, due to the presence of atmospheric turbulence. High Contrast Imaging (HCI) instruments have been designed to meet this challenge. HCI instruments are usually composed of a coronagraph coupled with the full onaxis corrective capability of an Extreme Adaptive Optics (ExAO) system. An efficient coronagraph separates the faint planet's light from the much brighter starlight, but the dynamic boiling speckles, created by the stellar image, make exoplanet detection impossible without the help of a wavefront correction device. The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system is a high performance HCI instrument developed at Subaru Telescope. The wavefront control system of SCExAO consists of three wavefront sensors (WFS) coupled with a 1024- actuator Micro-Electro-Mechanical-System (MEMS) deformable mirror (DM). MEMS DMs offer a large actuator density, allowing high count DMs to be deployed in small size beams. Therefore, MEMS DMs are an attractive technology for Adaptive Optics (AO) systems and are particularly well suited for HCI instruments employing ExAO technologies. SCExAO uses coherent light modulation in the focal plane introduced by the DM, for

  20. MEMS Deformable Mirrors for Adaptive Optics in Astronomical Imaging

    NASA Astrophysics Data System (ADS)

    Cornelissen, S.; Bierden, P. A.; Bifano, T.

    We report on the development of micro-electromechanical (MEMS) deformable mirrors designed for ground and space-based astronomical instruments intended for imaging extra-solar planets. Three different deformable mirror designs, a 1024 element continuous membrane (32x32), a 4096 element continuous membrane (64x64), and a 331 hexagonal segmented tip-tilt-piston are being produced for the Planet Imaging Concept Testbed Using a Rocket Experiment (PICTURE) program, the Gemini Planet Imaging Instrument, and the visible nulling coronograph developed at JPL for NASA's TPF mission, respectively. The design of these polysilicon, surface-micromachined MEMS deformable mirrors builds on technology that was pioneered at Boston University and has been used extensively to correct for ocular aberrations in retinal imaging systems and for compensation of atmospheric turbulence in free-space laser communication. These light-weight, low power deformable mirrors will have an active aperture of up to 25.2mm consisting of thin silicon membrane mirror supported by an array of 1024 to 4096 electrostatic actuators exhibiting no hysteresis and sub-nanometer repeatability. The continuous membrane deformable mirrors, coated with a highly reflective metal film, will be capable of up to 4μm of stroke, have a surface finish of <10nm RMS with a fill factor of 99.8%. The segmented device will have a range of motion of 1um of piston and a 600 arc-seconds of tip/tilt simultaneously and a surface finish of 1nm RMS. The individual mirror elements in this unique device, are designed such that they will maintain their flatness throughout the range of travel. New design features and fabrication processes are combined with a proven device architecture to achieve the desired performance and high reliability. Presented in this paper are device characteristic and performance results of these devices.

  1. Development of a fast steering secondary mirror prototype for the Giant Magellan Telescope

    NASA Astrophysics Data System (ADS)

    Cho, Myung K.; Corredor, Andrew; Dribusch, Christoph; Park, Kwijong; Kim, Young-Soo; Moon, Il-Kweon; Park, Won Hyun

    2012-09-01

    The Giant Magellan Telescope (GMT) will be a 25m class telescope currently in the design and development phase. The GMT will be a Gregorian telescope and equipped with a fast-steering secondary mirror (FSM). This secondary mirror is 3.2 m in diameter and built as seven 1.1 m diameter circular segments conjugated 1:1 to the seven 8.4m segments of the primary. The prototype of FSM (FSMP) development effort is led by the Korea Astronomy and Space Science Institute (KASI) with several collaborators in Korea, and the National Optical Astronomy Observatory (NOAO) in USA. The FSM has a tip-tilt feature to compensate image motions from the telescope structure jitters and the wind buffeting. For its dynamic performance, each of the FSM segments is designed in a lightweight mirror. Support system of the lightweight mirror consists of three axial actuators, one lateral support at the center, and a vacuum system. A parametric design study to optimize the FSM mirror configuration was performed. In this trade study, the optical image qualities and structure functions for the axial and lateral gravity print-through cases, thermal gradient effects, and dynamic performances will be discussed.

  2. Optical design of off-axis Cassegrain telescope using freeform surface at the secondary mirror

    NASA Astrophysics Data System (ADS)

    Gautam, Suryakant; Gupta, Amit; Singh, Ganga Sharan

    2015-02-01

    Freeform surfaces enable imaginative optics by providing abundant degrees of freedom for an optical designer as compared to spherical surfaces. An off-axis two-mirror-based telescope design is presented, in which the primary mirror is a concave prolate spheroid and the secondary mirror is freeform surface-based. The off-axis configuration is employed here for removing the central obscuration problem which otherwise limits the central maxima in the point spread function. In this proposed design, an extended X-Y polynomial is used as a surface descriptor for the off-axis segment of the secondary mirror. The coefficients of this extended polynomial are directly related to the Seidel aberrations, and are thus optimized here for a better control of asymmetric optical aberrations at various field points. For this design, the aperture stop is located 500 mm before the primary mirror and the entrance pupil diameter is kept as 80 mm. The effective focal length is 439 mm and covers a full field of view of 2 deg. The image quality obtained here is near diffraction limited which can be inferred from metrics such as the spot diagram and modulation transfer function.

  3. Evaluation of image quality in a Cassegrain-type telescope with an oscillating secondary mirror

    NASA Technical Reports Server (NTRS)

    Erickson, E. F.; Matthews, S.

    1975-01-01

    A ray-trace analysis is described of aberrations and extreme rays of a Cassegrain-type telescope with a tilted secondary mirror. The work was motivated by the need to understand the factors limiting image quality and to assist in the design of secondary mirrors for three telescopes with oscillating secondary mirrors (OSM) used at Ames Research Center for high altitude infrared astronomy. The telescopes are a 31-cm-diameter Dall-Kirkham (elliptical primary, spherical secondary) flown aboard a Lear jet, a 71-cm balloon-borne Dall-Kirkham flown on the AIROscope gondola, and a 91-cm true Cassegrain (parabolic primary, hyperbolic secondary) flown aboard a C-141 jet transport. The optics for these telescopes were not designed specifically for OSM operation, but all have OSM's and all must be used with various detector configurations; therefore, a facility that evaluates the performance of a telescope for a given configuration is useful. The analytical expressions are summarized and results for the above systems are discussed. Details of the calculation and a discussion of the computer program are given in the appendices.

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

    SciTech Connect

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

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Manipulation of visual biofeedback during gait with a time delayed adaptive Virtual Mirror Box

    PubMed Central

    2014-01-01

    Background A mirror placed in the mid-sagittal plane of the body has been used to reduce phantom limb pain and improve movement function in medical conditions characterised by asymmetrical movement control. The mirrored illusion of unimpaired limb movement during gait might enhance the effect, but a physical mirror is only capable of showing parallel movement of limbs in real time typically while sitting. We aimed to overcome the limitations of physical mirrors by developing and evaluating a Virtual Mirror Box which delays the mirrored image of limbs during gait to ensure temporal congruency with the impaired physical limb. Methods An application was developed in the CAREN system’s D-Flow software which mirrors selected limbs recorded by real-time motion capture to the contralateral side. To achieve phase shifted movement of limbs during gait, the mirrored virtual limbs are also delayed by a continuously calculated amount derived from past gait events. In order to accommodate non-normal proportions and offsets of pathological gait, the movements are morphed so that the physical and virtual contact events match on the mirrored side. Our method was tested with a trans-femoral amputee walking on a treadmill using his artificial limb. Joint angles of the elbow and knee were compared between the intact and mirrored side using cross correlation, root mean squared difference and correlation coefficients. Results The time delayed adaptive virtual mirror box produced a symmetrical looking gait of the avatar coupled with a reduction of the difference between the intact and virtual knee and elbow angles (10.86° and 5.34° reduced to 4.99° and 2.54° respectively). Dynamic morphing of the delay caused a non-significant change of toe-off events when compared to delaying by 50% of the previous gait cycle, as opposed to the initial contact events which showed a practically negligible but statistically significant increase (p < 0.05). Conclusions Adding an adaptive time

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

    SciTech Connect

    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.

  8. Astronomical Secondary Mirrors And Field Correctors: Special Challenges And Metrology Solutions Routinely Used At Brashear

    NASA Astrophysics Data System (ADS)

    Piche, Francios; Gardopee, G.; Clarkson, A.; Hull, T.

    2012-01-01

    It has been said that the secondary mirror is the most difficult optic of an astronomical telescope. Much of this difficulty is associated with metrology of a convex mirror. With the advent of highly deterministic modern optical finishing machines delivering high process convergence rates, like those processes used at L-3 Integrated Optical Systems (IOS), the availability of high-quality metrology on convex optical surfaces is of greater importance to take full advantage of those new technological capabilities. Once the surface error map is determined, modern optical finishing machines, like those at L-3 Integrated Optical Systems (IOS), can readily make the correction, even on optics mounted in their deliverable cells. Due to IOS' innovative engineering coupled with our extensive experience with large, fast secondary mirrors, we have delivered exceptional mirrors on short schedules. We frequently address requirements where the optical figure must be controlled to a few nanometers in wavefront error, and associated metrology must address not only low spatial frequencies (LSF), but also mid spatial frequencies (MSF) and high spatial frequencies (HSF). Special tooling and techniques that control the accumulated error are described, and examples of control of all spatial frequencies presented. Methods are available at IOS to remove predicted mounting dimples whether measured in-situ with the optics mounted in its cell or predicted from a finite-element model of the mounted optic. We will also describe metrology methods for astronomical field correctors.

  9. Reliability of MEMS deformable mirror technology used in adaptive optics imaging systems

    NASA Astrophysics Data System (ADS)

    Hartzell, Allyson L.; Cornelissen, Steven A.; Bierden, Paul A.; Lam, Charlie V.; Davis, Daniel F.

    2010-02-01

    Deformable mirror (DM) technology based on microelectromechanical systems (MEMS) technology produced by Boston Micromachines Corporation has been demonstrated to be an enabling component in a variety of adaptive optics applications such as high contrast imaging in astronomy, multi object adaptive optics, free-space laser communication, and microscopy. Many of these applications require DMs with thousands of actuators operating at frame rates up to 10 kHz for many years requiring sufficient device reliability to avoid device failures. In this paper we present improvements in MEMS deformable mirrors for reliability along with test data and device lifetime prediction that show trillions of actuator-cycles can be achieved without failures.

  10. Fabrication of experimental three-meter space telescope primary and secondary mirror support structure

    NASA Technical Reports Server (NTRS)

    Mishler, H. W.

    1974-01-01

    The fabrication of prototype titanium alloy primary and secondary mirror support structures for a proposed experimental three-meter space telescope is discussed. The structure was fabricated entirely of Ti-6Al-4V tubing and plate. Fabrication included the development of procedures including welding, forming, and machining. Most of the structures was fabricated by gas-shielding tungsten-arc (GTA) welding with several major components fabricated by high frequency resistance (HFR) welding.

  11. Silicon carbide deformable mirror with 37 actuators for adaptive optics

    NASA Astrophysics Data System (ADS)

    Ahn, Kyohoon; Rhee, Hyug-Gyo; Yang, Ho-Soon; Kihm, Hagyong

    2015-11-01

    We present a prototype of a silicon carbide (SiC) deformable mirror (DM) for high power laser applications. The DM has a continuous SiC faceplate, the diameter and the thickness of which are 100 mm and 2 mm, respectively, and 37 stack-type piezoelectric actuators arranged in a rectangular grid. Compared with the glass faceplates used for conventional DMs, SiC has a high thermal diffusivity that effectively minimizes mirror distortions due to thermal gradients. The faceplate is thick enough for possible integration with monolithic cooling channels inside the faceplate. The faceplate without cooling channels presented in this paper has a high bending stiffness compared with glass DMs, but the proposed actuator configuration has flexure supports to reduce the shear stress at the adhesive while preserving optical performances. To examine the characteristics of the SiC DM, we simulated influence functions (IFs) by using a finite element analysis and then compared these results with the IF measured by using an optical interferometer. The optical performance of the DM was verified by generating Zernike polynomial modes based on the measured IF.

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

    SciTech Connect

    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.

  13. Asymmetric fMRI adaptation reveals no evidence for mirror neurons in humans

    PubMed Central

    Lingnau, Angelika; Gesierich, Benno; Caramazza, Alfonso

    2009-01-01

    Neurons in macaque ventral premotor cortex and inferior parietal lobe discharge during both the observation and the execution of motor acts. It has been claimed that these so-called mirror neurons form the basis of action understanding by matching the visual input with the corresponding motor program (direct matching). Functional magnetic resonance imaging (fMRI) adaptation can be used to test the direct matching account of action recognition by determining whether putative mirror neurons show adaptation for repeated motor acts independently of whether they are observed or executed. An unambiguous test of the hypothesis requires that the motor acts be meaningless to ensure that any adaptation effect is directly because of movement recognition/motor execution and not contextually determined inferences. We found adaptation for motor acts that were repeatedly observed or repeatedly executed. We also found adaptation for motor acts that were first observed and then executed, as would be expected if a previously seen act primed the subsequent execution of that act. Crucially, we found no signs of adaptation for motor acts that were first executed and then observed. Failure to find cross-modal adaptation for executed and observed motor acts is not compatible with the core assumption of mirror neuron theory, which holds that action recognition and understanding are based on motor simulation. PMID:19497880

  14. Nanostructure Secondary-Mirror Apodizing Mask for Transmitter Signal Suppression in a Duplex Telescope

    NASA Technical Reports Server (NTRS)

    Hagopian, John; Livas, Jeffrey; Shiri, Shahram; Getty, Stephanie; Tveekrem, June; Butler, James

    2012-01-01

    A document discusses a nanostructure apodizing mask, made of multi-walled carbon nanotubes, that is applied to the centers (or in and around the holes) of the secondary mirrors of telescopes that are used to interferometrically measure the strain of space-time in response to gravitational waves. The shape of this ultra-black mask can be adjusted to provide a smooth transition to the clear aperture of the secondary mirror to minimize diffracted light. Carbon nanotubes grown on silicon are a viable telescope mirror substrate, and can absorb significantly more light than other black treatments. The hemispherical reflectance of multi-walled carbon nanotubes grown at GSFC is approximately 3 to 10 times better than a standard aerospace paint used for stray light control. At the LISA (Laser Interferometer Space Antenna) wavelength of 1 micron, the advantage over paint is a factor of 10. Primarily, in the center of the secondary mirror (in the region of central obscuration, where no received light is lost) a black mask is applied to absorb transmitted light that could be reflected back into the receiver. In the LISA telescope, this is in the center couple of millimeters. The shape of this absorber is critical to suppress diffraction at the edge. By using the correct shape, the stray light can be reduced by approximately 10 to the 9 orders of magnitude versus no center mask. The effect of the nanotubes has been simulated in a stray-light model. The effect of the apodizing mask has been simulated in a near-field diffraction model. Specifications are geometry-dependent, but the baseline design for the LISA telescope has been modeled as well. The coatings are somewhat fragile, but work is continuing to enhance adhesion.

  15. Deformable mirror based on piezoelectric actuators for the adaptive system of the Iskra-6 facility

    SciTech Connect

    Bokalo, S Yu; Zhupanov, V G; Lyakhov, D M; Mizin, P P; Smekalin, V P; Shanin, Oleg I; Shchipalkin, V I; Garanin, Sergey G; Grigorovich, S V; Koltygin, M O; Kulikov, S M; Manachinckii, A N; Ogorodnikov, A V; Smyshlyaev, S P; Sukharev, Stanislav A

    2007-08-31

    The main problem in developing high-power pulsed laser facilities (NIF, LMJ, and Iskra-6) is to provide the required quality of their output radiation. For this purpose, adaptive optical systems (AOSs) are used in all these facilities. The present research is devoted to determining the characteristics and working out the most troublesome elements of the AOS - the wavefront sensor and wide-aperture adaptive mirror for the Iskra-6 facility. (selected papers reported at the conference 'laser optics 2006')

  16. Segmented adaptive optic mirrors for laser power beaming and other space applications

    SciTech Connect

    Bennett, H.E.

    1996-12-31

    In order to effectively beam laser power into space to power satellites or to remove space debris in mid or high earth orbit very large mirrors (perhaps 12 m in diameter or more) and an adaptive optic system to penetrate the atmosphere are required. Mirrors with adaptive optic segment sizes less than the equivalent Fried coefficient for atmospheric turbulence (typically 3 - 5 cm at zenith in the visible region of the spectrum) are optimum for atmospheric penetration. These new mirrors may have hundreds of thousands of segments. The behavior of such mirrors under high powered laser irradiation is not clear, although for a large mirror both average and peak irradiation levels will be very low. Attention must be paid to penetration of laser energy into the gaps between segments and to the cumulative effect of edge diffraction. These problems do not appear to be severe and this new class of optics appears to offer new possibilities for use in space. It may change the way in which one looks at telescopes for space applications.

  17. Correction of vortex laser beam in a closed-loop adaptive system with bimorph mirror.

    PubMed

    Starikov, F A; Kochemasov, G G; Koltygin, M O; Kulikov, S M; Manachinsky, A N; Maslov, N V; Sukharev, S A; Aksenov, V P; Izmailov, I V; Kanev, F Yu; Atuchin, V V; Soldatenkov, I S

    2009-08-01

    The phase correction of a vortex laser beam is undertaken in the closed-loop adaptive system including a Hartmann-Shack wavefront sensor with singular reconstruction technique and a bimorph piezoceramic mirror. After correction the vortex doughnutlike beam is focused into a beam with bright axial spot that considerably increases the Strehl ratio and optical system resolution. Since the phase break cannot be exactly reproduced on the flexible mirror surface, off-axis vortices appear in the far field at the beam periphery. PMID:19649065

  18. Adaptive Assessment for Nonacademic Secondary Reading.

    ERIC Educational Resources Information Center

    Hittleman, Daniel R.

    Adaptive assessment procedures are a means of determining the quality of a reader's performance in a variety of reading situations and on a variety of written materials. Such procedures are consistent with the idea that there are functional competencies which change with the reading task. Adaptive assessment takes into account that a lack of…

  19. The actuator design and the experimental tests of a new technology large deformable mirror for visible wavelengths adaptive optics

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

    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 the inductance depends on the mover position, the electronics of this generator, provided with an inductance measure circuit, works also as a displacement sensor, supplying the control system with an accurate feed-back signal. A preliminary prototype, built according to the several FEA thermo-magnetic analyses, has undergone some preliminary laboratory tests. The results of these checks, matching the design results in terms of power and force, show that the the magnetic design addresses the severe specifications.

  20. Secondary tasks impair adaptation to step and gradual visual displacements

    PubMed Central

    Galea, J.M.; Sami, S.; Albert, N.B.; Miall, R.C.

    2016-01-01

    Performing two competing tasks can result in dividing cognitive resources between the tasks and impaired motor adaptation. In previous work we have reported impaired learning when participants had to switch from one visual displacement adaptation task to another. Here we examined whether or not a secondary task had a similar effect on adaptation to a visual displacement . The resource dividing task involved simultaneously adapting to a step visual displacement whilst vocally shadowing an auditory stimulus . The switching task required participants to adapt to opposing visual displacements in an alternating manner with the left and right hands. We found that both manipulations had a detrimental effect on adaptation rate. We then integrated these tasks and found the combination caused a greater decrease in adaptation rate than either manipulation in isolation. Experiment 2 showed that adaptation to a gradually imposed visual displacement was influenced in a similar manner to step adaptation. Therefore although gradual adaptation involves minimal awareness it still can be disrupted by a cognitively demanding secondary task. We propose that awareness and cognitive resource can be regarded as qualitatively different but that awareness may be a marker of the amount of resource required. For example, large errors are both noticed and require substantial cognitive resource to connect. However a lack of awareness does not mean an adaptation task will be resistant to interference from a resource consuming secondary task. PMID:20101396

  1. An error function minimization approach for the inverse problem of adaptive mirrors tuning

    NASA Astrophysics Data System (ADS)

    Vannoni, Maurizio; Yang, Fan; Siewert, Frank; Sinn, Harald

    2014-09-01

    Adaptive x-ray optics are more and more used in synchrotron beamlines, and it is probable that they will be considered for the future high-power free-electron laser sources, as the European XFEL now under construction in Hamburg, or similar projects now in discussion. These facilities will deliver a high power x-ray beam, with an expected high heat load delivered on the optics. For this reason, bendable mirrors are required to actively compensate the resulting wavefront distortion. On top of that, the mirror could have also intrinsic surface defects, as polishing errors or mounting stresses. In order to be able to correct the mirror surface with a high precision to maintain its challenging requirements, the mirror surface is usually characterized with a high accuracy metrology to calculate the actuators pulse functions and to assess its initial shape. After that, singular value decomposition (SVD) is used to find the signals to be applied into the actuators, to reach the desired surface deformation or correction. But in some cases this approach could be not robust enough for the needed performance. We present here a comparison between the classical SVD method and an error function minimization based on root-mean-square calculation. Some examples are provided, using a simulation of the European XFEL mirrors design as a case of study, and performances of the algorithms are evaluated in order to reach the ultimate quality in different scenarios. The approach could be easily generalized to other situations as well.

  2. A PSD (position sensing device) to map the shift and tilt of the SRT secondary mirror

    NASA Astrophysics Data System (ADS)

    Pisanu, Tonino; Buffa, Franco; Concu, Raimondo; Marongiu, Pasqualino; Pili, Mauro; Poppi, Sergio; Serra, Giampaolo; Urru, Enrico; Vargiu, Gianpaolo

    2014-07-01

    The Sardinia Radio Telescope (SRT) Metrology team has started to install the initial group of devices on the new 64 meters radio-telescope. These devices will be devoted for the realization of the antenna deformation control system: an electronic inclinometer able to monitor the alidade deformations and a Position Sensing Device (PSD) able to map the secondary mirror (M2) displacements and tilts. The inclinometer is used to map the rail conditions, the azimuthal axis inclination and the thermal effects on the alidade structure. The PSD will be used to measure the secondary mirror displacements induced by the gravity and by the thermal deformations that produce shifts and tilts with respect to it s ideal optical alignment. The PSD will be traced by a laser diode installed on a mechanically stable position inside the vertex room. Preliminarly we decided to characterize excursion range of M2, in order to know if the PSD measuring range of about +/- 10 mm is enough for our purposes. We designed, built and tested an optical measuring device, based on commercial CMOS with a wider measurement range of +/- 40 mm and with a resolution of around 0.1 mm. After a laboratory characterization at the 23 meters real distance, the PSD and the laser have been installed in the antenna. In this paper we show the results of the measurements performed by moving the antenna in elevation.

  3. Qualification and Testing of a Large Hot Slumped Secondary Mirror for Schwarzschild-Couder Imaging Air Cherenkov Telescopes

    NASA Astrophysics Data System (ADS)

    Rodeghiero, G.; Giro, E.; Canestrari, R.; Pernechele, C.; Sironi, G.; Pareschi, G.; Lessio, L.; Conconi, P.

    2016-05-01

    Dual-mirror Schwarzschild-Couder (SC) telescopes are based on highly aspherical optics, and they represent a novel design in the world of very high energy astrophysics. This work addresses the realization and the qualification of the secondary mirror for an SC telescope, named ASTRI, developed in the context of the Cherenkov Telescope Array Observatory. The discussion surveys the overall development from the early design concept to the final acceptance optical tests.

  4. Adaptive Optics: Arroyo Simulation Tool and Deformable Mirror Actuation Using Golay Cells

    NASA Technical Reports Server (NTRS)

    Lint, Adam S.

    2005-01-01

    The Arroyo C++ libraries, written by Caltech post-doc student Matthew Britton, have the ability to simulate optical systems and atmospheric signal interference. This program was chosen for use in an end-to-end simulation model of a laser communication system because it is freely distributed and has the ability to be controlled by a remote system or "smart agent." Proposed operation of this program by a smart agent has been demonstrated, and the results show it to be a suitable simulation tool. Deformable mirrors, as a part of modern adaptive optics systems, may contain thousands of tiny, independently controlled actuators used to modify the shape of the mirror. Each actuator is connected to two wires, creating a cumbersome and expensive device. Recently, an alternative actuation method that uses gas-filled tubes known as Golay cells has been explored. Golay cells, operated by infrared lasers instead of electricity, would replace the actuator system thereby creating a more compact deformable mirror. The operation of Golay cells and their ability to move a deformable mirror in excess of the required 20 microns has been demonstrated. Experimentation has shown them to be extremely sensitive to pressure and temperature, making them ideal for use in a controlled environment.

  5. A microprocessor-based position control system for a telescope secondary mirror

    NASA Technical Reports Server (NTRS)

    Lorell, K. R.; Barrows, W. F.; Clappier, R. R.; Lee, G. K.

    1983-01-01

    The pointing requirements for the Shuttle IR Telescope Facility (SIRTF), which consists of an 0.85-m cryogenically cooled IR telescope, call for an image stability of 0.25 arcsec. Attention is presently given to a microprocessor-based position control system developed for the control of the SIRTF secondary mirror, employing a special control law (to minimize energy dissipation), a precision capacitive position sensor, and a specially designed power amplifier/actuator combination. The microprocessor generates the command angular position and rate waveforms in order to maintain a 90 percent dwell time/10 percent transition time ratio independently of chop frequency or amplitude. Performance and test results of a prototype system designed for use with a demonstration model of the SIRTF focal plane fine guidance sensor are presented.

  6. Extreme Adaptive Optics Testbed: Performance and Characterization of a 1024 Deformable Mirror

    SciTech Connect

    Evans, J W; Morzinski, K; Severson, S; Poyneer, L; Macintosh, B; Dillon, D; REza, L; Gavel, D; Palmer, D

    2005-10-30

    We have demonstrated that a microelectrical mechanical systems (MEMS) deformable mirror can be flattened to < 1 nm RMS within controllable spatial frequencies over a 9.2-mm aperture making it a viable option for high-contrast adaptive optics systems (also known as Extreme Adaptive Optics). The Extreme Adaptive Optics Testbed at UC Santa Cruz is being used to investigate and develop technologies for high-contrast imaging, especially wavefront control. A phase shifting diffraction interferometer (PSDI) measures wavefront errors with sub-nm precision and accuracy for metrology and wavefront control. Consistent flattening, required testing and characterization of the individual actuator response, including the effects of dead and low-response actuators. Stability and repeatability of the MEMS devices was also tested. An error budget for MEMS closed loop performance will summarize MEMS characterization.

  7. High Resolution Imaging with Adaptive Optics at the Multiple Mirror Telescope

    NASA Astrophysics Data System (ADS)

    Lloyd-Hart, M.; McLeod, B. A.; Wittman, D.; Colucci, D.; McCarthy, D. W.; Angel, R.; Dekany, R.

    1992-12-01

    We present the latest results from an adaptive optics program being implemented at the MMT using a six element adaptive mirror. The tilt of the wavefront over each of the six telescopes is determined with a Shack-Hartmann type sensor using a 24times 24 pixel low-noise CCD. This system allows the MMT to operate at a resolution of 0.3'' at 2 microns -- near the diffraction limit of the individual 1.8-m telescopes. This resolution can be obtained within ~ 1' of any star with visual magnitude < 16, allowing high-resolution near-IR imaging with a NICMOS2 array of a wide variety of targets, including high-redshift galaxies and young and evolved stars. This system can also be used with the MMT operated as a phased array telescope. In this mode, the piston errors between the telescopes are determined by examining the Fourier transform of the combined 2-micron image of the natural guide star using a fast-readout InSb array. In this configuration we have achieved a resolution of 0.075''. In good seeing we expect to obtain images of interest within the isoplanatic patch of guide stars with K magnitude <7. We acknowledge financial support from the NSF (AST92-03336) and the Flintridge Foundation. The adaptive mirror was donated by ThermoTrex Corp.

  8. Woofer-tweeter adaptive optics in very strong turbulence using a magnetic-liquid deformable mirror

    NASA Astrophysics Data System (ADS)

    Brousseau, Denis; Véran, Jean-Pierre; Thibault, Simon; Borra, Ermanno F.; F.-Boivin, Simon.

    2012-07-01

    We present progress towards the development of a woofer-tweeter adaptive optics (AO) system using the first 37 actuators of a 91-actuator magnetic-liquid deformable mirror (MLDM) and a magnetic 97-actuator DM from ALPAO. The MLDM, which has both very large single-actuator and inter-actuator strokes, but a low bandwidth, is used as woofer, whereas the high bandwidth and lower stroke ALPAO DM is used as tweeter. The ALPAO DM should improve the bandwidth of the MLDM while the MLDM will allow correction of strong aberrations.

  9. When mirroring is both simple and "smart": how mimicry can be embodied, adaptive, and non-representational.

    PubMed

    Carr, Evan W; Winkielman, Piotr

    2014-01-01

    The concept of mirroring has become rather ubiquitous. One of the most fundamental empirical and theoretical debates within research on mirroring concerns the role of mental representations: while some models argue that higher-order representational mechanisms underpin most cases of mirroring, other models argue that they only moderate a primarily non-representational process. As such, even though research on mirroring-along with its neural substrates, including the putative mirror neuron system-has grown tremendously, so too has confusion about what it actually means to "mirror". Using recent research on spontaneous imitation, we argue that flexible mirroring effects can be fully embodied and dynamic-even in the absence of higher-order mental representations. We propose that mirroring can simply reflect an adaptive integration and utilization of cues obtained from the brain, body, and environment, which is especially evident within the social context. Such a view offers reconciliation among both representational and non-representational frameworks in cognitive neuroscience, which will facilitate revised interpretations of modern (and seemingly divergent) findings on when and how these embodied mirroring responses are employed. PMID:25071532

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

    PubMed

    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. PMID:27526166

  11. Adaptive control of piezoelectric fast steering mirror for high precision tracking application

    NASA Astrophysics Data System (ADS)

    Wang, Geng; Rao, Changhui

    2015-03-01

    A piezoelectric fast steering mirror (PFSM) is a complex, strong coupling nonlinear system that integrates optics, mechanics, electrics, and control. Due to the existence of hysteresis nonlinearity, mechanical resonance, and all kinds of disturbances, precise tracking control of a PFSM is a challenging task. This paper presents a comprehensive study of modeling, controller design, and simulation evaluation for a PFSM system. First a general model of a PFSM system integrating mechanical dynamics, electrical dynamics, and hysteresis nonlinearity is proposed, and then a robust adaptive controller is developed under both unknown hysteresis nonlinearities and parameter uncertainties. The parameters needed directly in the formulation of the controller are adaptively estimated. The proposed control law ensures the uniform boundedness of all signals in the closed-loop system. Furthermore, a stability analysis of the control system is performed to guarantee that the output tracking error converges to zero asymptotically. Finally, simulation tests with different motion trajectories are conducted to verify the effectiveness of the proposed method.

  12. Control of the unilluminated deformable mirror actuators in an altitude-conjugated adaptive optics system

    PubMed

    Veran

    2000-07-01

    Off-axis observations made with adaptive optics are severely limited by anisoplanatism errors. However, conjugating the deformable mirror to an optimal altitude can reduce these errors; it is then necessary to control, through extrapolation, actuators that are not measured by the wave-front sensor (unilluminated actuators). In this study various common extrapolation schemes are investigated, and an optimal method that achieves a significantly better performance is proposed. This extrapolation method involves a simple matrix multiplication and will be implemented in ALTAIR, the Gemini North Telescope adaptive optics system located on Mauna Kea, Hawaii. With this optimal method, the relative H-band Strehl reduction due to extrapolation errors is only 5%, 16%, and 30% when the angular distance between the guide source and the science target is 20, 40 and 60 arc sec, respectively. For a site such as Mauna Kea, these errors are largely outweighed by the increase in the size of the isoplanatic field. PMID:10883986

  13. fMRI Adaptation Reveals Mirror Neurons in Human Inferior Parietal Cortex

    PubMed Central

    Chong, Trevor T.-J.; Cunnington, Ross; Williams, Mark A.; Kanwisher, Nancy; Mattingley, Jason B.

    2009-01-01

    Summary Mirror neurons, as originally described in the macaque, have two defining properties [1] and [2]: They respond specifically to a particular action (e.g., bringing an object to the mouth), and they produce their action-specific responses independent of whether the monkey executes the action or passively observes a conspecific performing the same action. In humans, action observation and action execution engage a network of frontal, parietal, and temporal areas. However, it is unclear whether these responses reflect the activity of a single population that represents both observed and executed actions in a common neural code or the activity of distinct but overlapping populations of exclusively perceptual and motor neurons [3]. Here, we used fMRI adaptation to show that the right inferior parietal lobe (IPL) responds independently to specific actions regardless of whether they are observed or executed. Specifically, responses in the right IPL were attenuated when participants observed a recently executed action relative to one that had not previously been performed. This adaptation across action and perception demonstrates that the right IPL responds selectively to the motoric and perceptual representations of actions and is the first evidence for a neural response in humans that shows both defining properties of mirror neurons. PMID:18948009

  14. Development of lightweight mirror elements for the Euro50 mirrors

    NASA Astrophysics Data System (ADS)

    Bennett, Harold E.; Romeo, Robert C.; Shaffer, Joseph J.; Chen, Peter C.

    2004-07-01

    New, very large telescopes with apertures of 30, 50, and 100 meters are being proposed by the astronomical community. Superpolished or ultrapolished mirrors with low scattered light levels and the use of adaptive optics for near-diffraction-limited performance would make such large telescopes a turning point in astronomy. The secondary mirror for the Euro50 will be a four meter adaptive optic made of a low expansion graphite-filled cyanate ester resin composite produced using a replica transfer technique. We have made three 1/3rd meter diameter prototype composite adaptive optic mirrors of this cyanate ester composite material. Because of the embedded graphite fibers, the composite material has a measured expansion coefficient in the 10-8 range, as has Zerodur or ULE glass. It is very much lighter, more rugged and more economical than Zerodur or ULE, and can be fabricated in weeks, not months. The Zerodur mandrels upon which these replica transfer mirrors are made are superpolished using centrifugal elutriation, so the replica surface has an rms roughness of 0.6 to 0.8 nm. It thus scatters about an order of magnitude less light than typical conventionally polished astronomical mirrors. In adaptive optic mirrors with sub-mm thick faceplates the number of plies used is insufficient to produce an isotropic surface. For mirrors 2 mm thick, with more plies, the surfaces are isotropic, and the slight astigmatism sometimes resulting from the mesh in the ply can be corrected by actuators to make them attractive mirrors. They must be supported to maintain a good optical figure over a meter diameter mirror. The support requirement may be met by using a new type of mechanical/piezoelectric actuator adjustable to a fraction of a wavelength. The mechanical actuators have a coarse adjust of over an mm and a fine adjust of less than a wavelength of light. They can be used in series with a novel type of piezoelectric actuator for final static adjustment. The low voltage, up to 2

  15. Error reduction and modeling for hexapod positioners of secondary mirrors for large ground-based telescopes

    NASA Astrophysics Data System (ADS)

    Sneed, Ryan C.; Keas, Paul J.

    2014-08-01

    The positioning requirements for secondary mirrors and instruments for large ground-based telescopes are becoming increasingly challenging. Modern telescope designs, such as LSST and TMT, are specifying repeatability and/or absolute accuracy limits below 10 μm and 10 μrad for the hexapod positioning systems generally used for these applications. Hexapod error sources, including lead screw pitch variations, windup, backlash, friction, thermal expansion, compliance, sensing, and joint node location uncertainties, are examined along with methods for reducing or eliminating these errors by mechanical means or through calibration. Alternative sensing approaches are discussed and their relative benefits are evaluated. Finally, a model-based design approach is presented for conducting initial design trade studies, assessing technical risk, predicting achievable performance, establishing subsystem and component requirements, and tracking positioning error budgets through the entire development process. A parametric actuator model and its initial results are described, and testing approaches are outlined to identify key model parameters and verify subsystem and component performance.

  16. Adaptive temporal and wavefront aberration correction for ultrafast lasers with a membrane deformable mirror

    NASA Astrophysics Data System (ADS)

    Sherman, Leah Bruner

    Two adaptive optic systems for correction of either temporal phase error and wavefront errors for ultrafast pulses are demonstrated. These systems consists of a computer controlled micromachined membrane deformable mirror (MMDM) and a genetic learning algorithm (GA). Nonlinear excitation such as two-photon fluorescence or second harmonic generation are used as feedback to the GA to determine the appropriate correction to apply to the mirror. Two MMDMs are used, a 30 x 8 mm, 39 actuator linear MMDM for pulse-shaping applications and a 15 mm diameter, 37 actuator wavefront MMDM. Linear pre-compensation of self-phase modulation (SPM) was experimentally demonstrated utilizing the linear MMDM in a linear pulse-shaper for ultrafast pulses. The nonlinear nature of SPM makes arbitrary polynomial compensation necessary. Pre-compensation of SPM generated in an optical fiber by a 10 fs pulse reduced the pulse from 30fs to 20fs. We demonstrates adaptive correction with the wavefront MMDM by corrected for coma and astigmatism in a reflective multiphoton scanning microscope. An f1, parabola produces a very tight focus with no aberration when it is perfectly aligned. However, when beam scanning is used for two-dimensional imaging the image is severely aberrated. The MMDM and the GA are able to find the best possible wavefront for aberration correction for each scanning position. The horizontal scanning range was increased from 60 mum without the adaptive correction to 170 mum, ≈3 times the uncorrected scanning range, and the vertical scanning range was increased by a comparable amount. This resulted in an increase in scanning area of 9 times. The wavefront MMDM was also used for adaptive correction of spherical aberration from focusing from air, deep into a water-based sample. This depth-based aberration results from an index of refraction mismatch between the sample and the immersion medium of the objective and occurs regardless of beam scanning or sample scanning. By

  17. Impact of resolution in multi-conjugate adaptive optics systems using segmented mirrors

    NASA Astrophysics Data System (ADS)

    Corej, Thomas A.; Schmidt, Jason D.

    2009-08-01

    In moderate-to-strong scintillation, multi-conjugate adaptive optics (MCAO) appears promising to compensate for amplitude and phase fluctuations. In this research, a MCAO system is simulated with a segmented deformable mirror (DM) reshaping the amplitude and the second DM (continuous) flattening the phase after propagation from the segmented mirror. A Gerchberg-Saxton (GS) type algorithm is used with Fresnel propagation between DM planes. The effects of varying the phase's apparent resolution on a segmented DM in the pupil plane is investigated. Results show the mean square error in the reshaped beam decreases as D/ro and Rytov number increase over the range of conditions tested (ro: 0.11 m - 0.36 m). The field-estimated Strehl ratio drops precipitously when the number of subapertures is increased beyond about 36 across, using a branch-pointtolerant unwrapper, due to the presence of branch points. On the second DM, by using the mean of the phase within each subaperture before back propagating to the first DM plane (inside the GS loop), the Strehl ratio was improved 6 - 11 percent using 4 - 19 actuators across. Further a novel method of cascading segmented DMs, of increasingly higher resolution, doing amplitude reshaping followed by a continuous DM to flatten the phase is explored.

  18. Vrala: designing and prototyping a novel high-efficiency actuator for large adaptive mirrors

    NASA Astrophysics Data System (ADS)

    Del Vecchio, Ciro; Marignetti, Fabrizio; Agapito, Guido; Tomassi, Giovanni; Riccardi, Armando

    2010-07-01

    The next-generation Extremely Large Telescopes adaptive optics systems require high-order, long-stroke, quite large deformable mirrors. Higher forces and greater actuator densities than the ones provided by the current technology are needed, still maintaining its requests in terms of accuracy and bandwidth. The electromagnetic "Vrala" actuator can accomplish this very demanding goal. Based on a very simple magnetic circuit, providing a compact device, it allows to deliver a large force with very low power dissipations. With a typical efficiency of about 7 N/W and an overall radius that allows actuator separations as low as 25 mm, the deformable mirror can be actuated on small spatial scales, and/or its thickness can be increased, in order to simplify the manufacturing, with a little thermal impact. This paper will mainly discuss the magnetic design of the proposed actuator, its effects on the thermal response of the device as well as its behavior in a closed loop control system - from the geometrical optimization process to the dynamic performances. A prototype built accordingly to the proposed design has been tested. The test set-up, as well as the first set of the measured data, well matching the results of the numerical simulations, will also be shown.

  19. When mirroring is both simple and “smart”: how mimicry can be embodied, adaptive, and non-representational

    PubMed Central

    Carr, Evan W.; Winkielman, Piotr

    2014-01-01

    The concept of mirroring has become rather ubiquitous. One of the most fundamental empirical and theoretical debates within research on mirroring concerns the role of mental representations: while some models argue that higher-order representational mechanisms underpin most cases of mirroring, other models argue that they only moderate a primarily non-representational process. As such, even though research on mirroring—along with its neural substrates, including the putative mirror neuron system—has grown tremendously, so too has confusion about what it actually means to “mirror”. Using recent research on spontaneous imitation, we argue that flexible mirroring effects can be fully embodied and dynamic—even in the absence of higher-order mental representations. We propose that mirroring can simply reflect an adaptive integration and utilization of cues obtained from the brain, body, and environment, which is especially evident within the social context. Such a view offers reconciliation among both representational and non-representational frameworks in cognitive neuroscience, which will facilitate revised interpretations of modern (and seemingly divergent) findings on when and how these embodied mirroring responses are employed. PMID:25071532

  20. Adaptive optics vision simulator based on 35 element bimorph deformable mirror

    NASA Astrophysics Data System (ADS)

    Zhao, Lina; Dai, Yun; Xiao, Fei; Kang, Jian; Zhao, Haoxin; Bao, Hua; Zhou, Hong; Zhou, Yifeng; Zhang, Yudong

    2014-09-01

    A novel adaptive optics vision simulator (AOVS) is presented and characterized for several design features, including automated measuring and compensating eye's aberrations up to the fifth order, which fully cover aberrations typically found in the human eye, even for the cases of highly aberrated eyes. Especially, it is equipped with 35 elements bimorph deformable mirror with bigger stroke and smaller size, which could help establish near-diffraction-limited ocular optics condition. To investigate the validity of this apparatus, pilot data under different aberration correction pattern from one subjects are collected, and contrast sensitivity function (CSF), an important psychophysical function in vision, is obtained also. Results from living eyes show a practically perfect aberration correction and demonstrate the utility of this system.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Anastigmatic three-mirror telescope

    NASA Technical Reports Server (NTRS)

    Korsch, D. G. (Inventor)

    1978-01-01

    A three-mirror telescope for extraterrestrial observations is described. An ellipsoidal primary mirror, a hyperbolic secondary mirror, and an ellipsoidal tertiary mirror, produce an image in a conveniently located finite plane for viewing.

  3. Six degrees of freedom, sub-micrometer positioning system for secondary mirrors

    NASA Astrophysics Data System (ADS)

    Sneed, Ryan C.; Cash, Michael F.; Chambers, Trevor S.; Janzen, Paul C.

    2010-07-01

    Secondary mirrors for large ground-based telescopes often require positioning systems with payload capacities around 1000 kg, relative accuracies within a few micrometers, and resonant frequencies above 15 Hz. A suitable six-legged parallel manipulator, or hexapod, has been developed for sub-micron level positioning of large optical payloads in six degrees of freedom. This 1000 kg class hexapod has tip/tilt rotational ranges of +/-1800 arcsec, relative accuracies within 1%, and resolutions of better than +/-0.2 arcsec, along with a piston translational range of +/-30 mm, relative accuracy within 1%, and resolution of better than +/-1 μm. The center of rotation of the system may be placed at an arbitrary location within the overall range limitations. The axial stiffness of each of the six actuators tested greater than 100 N/μm. The actuators use high precision roller screws and employ two degree of freedom universal end-joints. The preload on the joints eliminates backlash due to transitions from tension to compression and maintains friction moment of <10 Nm. An additional rotational degree of freedom is allowed in the body of the actuator to achieve the proper kinematic constraints for the motion platform. The actuators have power-off hold capability to protect against power loss and reduce heat dissipation. Overall heat dissipation has been measured and techniques have been studied to reduce its impact. The paper describes the actuator design and hexapod performance in support of planned use in ground test and validation of the James Webb Space Telescope.

  4. Comparison of Adaptive Optics and Phase-Conjugate Mirrors for Correction of Aberrations in Double-Pass Amplifiers

    NASA Astrophysics Data System (ADS)

    Jackel, Steven; Moshe, Inon; Lavi, Raphy

    2003-02-01

    Correction of birefringence-induced effects (depolarization and bipolar focusing) were achieved in double-pass amplifiers by use of a Faraday rotator between the laser rod and the retroreflecting optic. A necessary condition was ray retrace. Retrace was limited by imperfect conjugate-beam fidelity and by nonreciprocal refractive indices. We compared various retroreflectors: stimulated-Brillouin-scatter phase-conjugate mirrors (PCMs), PCMs with rod-to-PCM relay imaging (IPCM), IPCMs with astigmatism-correcting adaptive optics, and all-adaptive-optics imaging variable-radius mirrors. Results with flash-lamp-pumped, Nd:Cr:GSGG double-pass amplifiers showed the superiority of adaptive optics over nonlinear optics retroreflectors in terms of maximum average power, improved beam quality, and broader oscillator pulse duration /bandwidth operating range. Hybrid PCM-adaptive optics retroreflectors yielded intermediate power /beam-quality results.

  5. Comparison of adaptive optics and phase-conjugate mirrors for correction of aberrations in double-pass amplifiers.

    PubMed

    Jackel, Steven; Moshe, Inon; Lavi, Raphy

    2003-02-20

    Correction of birefringence-induced effects (depolarization and bipolar focusing) were achieved in double-pass amplifiers by use of a Faraday rotator between the laser rod and the retroreflecting optic. A necessary condition was ray retrace. Retrace was limited by imperfect conjugate-beam fidelity and by nonreciprocal refractive indices. We compared various retroreflectors: stimulated-Brillouin-scatter phase-conjugate mirrors (PCMs), PCMs with rod-to-PCM relay imaging (IPCM), IPCMs with astigmatism-correcting adaptive optics, and all-adaptive-optic imaging variable-radius mirrors. Results with flash-lamp-pumped, Nd:Cr:GSGG double-pass amplifiers showed the superiority of adaptive optics over nonlinear optic retroreflectors in terms of maximum average power, improved beam quality, and broader oscillator pulse duration/bandwidth operating range. Hybrid PCM-adaptive optics retroreflectors yielded intermediate power/beam-quality results. PMID:12617213

  6. Age-Specific Effects of Mirror-Muscle Activity on Cross-Limb Adaptations Under Mirror and Non-Mirror Visual Feedback Conditions.

    PubMed

    Reissig, Paola; Stöckel, Tino; Garry, Michael I; Summers, Jeffery J; Hinder, Mark R

    2015-01-01

    Cross-limb transfer (CLT) describes the observation of bilateral performance gains due to unilateral motor practice. Previous research has suggested that CLT may be reduced, or absent, in older adults, possibly due to age-related structural and functional brain changes. Based on research showing increases in CLT due to the provision of mirror visual feedback (MVF) during task execution in young adults, our study aimed to investigate whether MVF can facilitate CLT in older adults, who are known to be more reliant on visual feedback for accurate motor performance. Participants (N = 53) engaged in a short-term training regime (300 movements) involving a ballistic finger task using their dominant hand, while being provided with either visual feedback of their active limb, or a mirror reflection of their active limb (superimposed over the quiescent limb). Performance in both limbs was examined before, during and following the unilateral training. Furthermore, we measured corticospinal excitability (using TMS) at these time points, and assessed muscle activity bilaterally during the task via EMG; these parameters were used to investigate the mechanisms mediating and predicting CLT. Training resulted in significant bilateral performance gains that did not differ as a result of age or visual feedback (both p > 0.1). Training also elicited bilateral increases in corticospinal excitability (p < 0.05). For younger adults, CLT was significantly predicted by performance gains in the trained hand (β = 0.47), whereas for older adults it was significantly predicted by mirror activity in the untrained hand during training (β = 0.60). The present study suggests that older adults are capable of exhibiting CLT to a similar degree to younger adults. The prominent role of mirror activity in the untrained hand for CLT in older adults indicates that bilateral cortical activity during unilateral motor tasks is a compensatory mechanism. In this particular task, MVF did not facilitate the

  7. Age-Specific Effects of Mirror-Muscle Activity on Cross-Limb Adaptations Under Mirror and Non-Mirror Visual Feedback Conditions

    PubMed Central

    Reissig, Paola; Stöckel, Tino; Garry, Michael I.; Summers, Jeffery J.; Hinder, Mark R.

    2015-01-01

    Cross-limb transfer (CLT) describes the observation of bilateral performance gains due to unilateral motor practice. Previous research has suggested that CLT may be reduced, or absent, in older adults, possibly due to age-related structural and functional brain changes. Based on research showing increases in CLT due to the provision of mirror visual feedback (MVF) during task execution in young adults, our study aimed to investigate whether MVF can facilitate CLT in older adults, who are known to be more reliant on visual feedback for accurate motor performance. Participants (N = 53) engaged in a short-term training regime (300 movements) involving a ballistic finger task using their dominant hand, while being provided with either visual feedback of their active limb, or a mirror reflection of their active limb (superimposed over the quiescent limb). Performance in both limbs was examined before, during and following the unilateral training. Furthermore, we measured corticospinal excitability (using TMS) at these time points, and assessed muscle activity bilaterally during the task via EMG; these parameters were used to investigate the mechanisms mediating and predicting CLT. Training resulted in significant bilateral performance gains that did not differ as a result of age or visual feedback (both p > 0.1). Training also elicited bilateral increases in corticospinal excitability (p < 0.05). For younger adults, CLT was significantly predicted by performance gains in the trained hand (β = 0.47), whereas for older adults it was significantly predicted by mirror activity in the untrained hand during training (β = 0.60). The present study suggests that older adults are capable of exhibiting CLT to a similar degree to younger adults. The prominent role of mirror activity in the untrained hand for CLT in older adults indicates that bilateral cortical activity during unilateral motor tasks is a compensatory mechanism. In this particular task, MVF did not facilitate the

  8. Characterization Of High-Stroke High-Aspect Ratio Micro Electro Mechanical Systems Deformable Mirrors For Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Bouchti, Mohamed Amine

    Adaptive optics MEMS deformable mirror, in conjunction with Shack Hartman wave front sensor and real-time controller, is capable of correcting time-varying aberrations in imaging applications through manipulating its mirror surface. Adaptive optics systems in astronomy for next generation large telescopes (30 meter primary mirrors) require a high stroke of 10microm of mechanical displacement. This required stroke would be achieved by MEMS deformable mirrors fabricated with high aspect ratio techniques. This thesis will review the designs of various types of high aspect actuators consisting of folded springs with rectangular and circular membranes as well as X-beam actuators. Finite element analysis (FEA) simulations of these designs have shown the ability of each design to achieve a stroke of approximately 9.4 microm. Also, FEA simulations proved that the X-beam actuators provide the best spring support while preventing tilting. In addition, this thesis will discuss device characterization and voltage vs. displacement test results for the high aspect ratio gold MEMS 16 x 16 X-beam actuators deformable mirror that has been bonded and packaged. The results have shown that the device is capable of achieving approximately 5.5 microm in individual actuator testing and 7microm in dual actuator testing.

  9. In-the-plane design of an off-axis ophthalmic adaptive optics system using toroidal mirrors

    PubMed Central

    Liu, Zhuolin; Kocaoglu, Omer P.; Miller, Donald T.

    2013-01-01

    Adaptive optics (AO) ophthalmoscopes have garnered increased clinical and scientific use for imaging the microscopic retina. Unlike conventional ophthalmoscopes, however, AO systems are commonly designed with spherical mirrors that must be used off-axis. This arrangement causes astigmatism to accumulate at the retina and pupil conjugate planes, degrading AO performance. To mitigate this effect and more fully tap the benefit of AO, we investigated a novel solution based on toroidal mirrors. Derived 2nd order analytic solutions along with commercial ray tracing predict performance benefit of toroidal mirrors for ophthalmoscopic use. For the Indiana AO ophthalmoscope, a minimum of three toroids is required to achieve performance criteria for retinal image quality, beam displacement, and beam ellipticity. Measurements with fabricated toroids and retinal imaging on subjects substantiate the theoretical predictions. Comparison to off-the-plane method is also presented. PMID:24409397

  10. The Magellan Telescope Adaptive Secondary AO System: a visible and mid-IR AO facility

    NASA Astrophysics Data System (ADS)

    Close, Laird M.; Gasho, Victor; Kopon, Derek; Males, Jared; Follette, Katherine B.; Brutlag, Kevin; Uomoto, Alan; Hare, Tyson

    2010-07-01

    The Magellan Clay telescope is a 6.5m Gregorian telescope located in Chile at Las Campanas Observatory. The Gregorian design allows for an adaptive secondary mirror that can be tested off-sky in a straightforward manner. We have fabricated a 85 cm diameter aspheric adaptive secondary with our subcontractors and partners, the ASM passed acceptance tests in July 2010. This secondary has 585 actuators with <1 msec response times (0.7 ms typically). This adaptive secondary will allow low emissivity AO science. We will achieve very high Strehls (~98%) in the Mid-IR (3-26 microns) with the BLINC/MIRAC4 Mid-IR science camera. This will allow the first "super-resolution" and nulling Mid-IR studies of dusty southern objects. We will employ a high order (585 mode) pyramid wavefront sensor similar to that now successfully used at the Large Binocular Telescope. The relatively high actuator count will allow modest Strehls to be obtained in the visible (0.63-1.05 μm). Moderate (~20%) Strehls have already been obtained at 0.8 μm at the LBT with the same powerful combination of a next generation ASM and Pyramid WFS as we are providing for Magellan. Our visible light AO (VisAO) science camera is fed by an advanced triplet ADC and is piggy-backed on the WFS optical board. We have designed an additional "clean-up" very fast (2 kHz) tilt stabilization system for VisAO. Also a high-speed shutter will be used to block periods of poor correction. The VisAO facility can be reconfigured to feed an optical IFU spectrograph with 20 mas spaxels. The entire system passed CDR in June 2009, and is now finished the fabrication phase and is entering the integration phase. The system science and performance requirements, and an overview the design, interface and schedule for the Magellan AO system are presented here.

  11. Adaptive optimization of reference intensity for optical coherence imaging using galvanometric mirror tilting method

    NASA Astrophysics Data System (ADS)

    Kim, Ji-hyun; Han, Jae-Ho; Jeong, Jichai

    2015-09-01

    Integration time and reference intensity are important factors for achieving high signal-to-noise ratio (SNR) and sensitivity in optical coherence tomography (OCT). In this context, we present an adaptive optimization method of reference intensity for OCT setup. The reference intensity is automatically controlled by tilting a beam position using a Galvanometric scanning mirror system. Before sample scanning, the OCT system acquires two dimensional intensity map with normalized intensity and variables in color spaces using false-color mapping. Then, the system increases or decreases reference intensity following the map data for optimization with a given algorithm. In our experiments, the proposed method successfully corrected the reference intensity with maintaining spectral shape, enabled to change integration time without manual calibration of the reference intensity, and prevented image degradation due to over-saturation and insufficient reference intensity. Also, SNR and sensitivity could be improved by increasing integration time with automatic adjustment of the reference intensity. We believe that our findings can significantly aid in the optimization of SNR and sensitivity for optical coherence tomography systems.

  12. Stroke saturation on a MEMS deformable mirror for woofer-tweeter adaptive optics

    NASA Astrophysics Data System (ADS)

    Morzinski, Katie; Macintosh, Bruce; Gavel, Donald; Dillon, Daren

    2009-03-01

    High-contrast imaging of extrasolar planet candidates around a main-sequence star has recently been realized from the ground using current adaptive optics (AO) systems. Advancing such observations will be a task for the Gemini Planet Imager, an upcoming "extreme" AO instrument. High-order "tweeter" and low-order "woofer" deformable mirrors (DMs) will supply a >90%-Strehl correction, a specialized coronagraph will suppress the stellar flux, and any planets can then be imaged in the "dark hole" region. Residual wavefront error scatters light into the DM-controlled dark hole, making planets difficult to image above the noise. It is crucial in this regard that the high-density tweeter, a micro-electrical mechanical systems (MEMS) DM, have sufficient stroke to deform to the shapes required by atmospheric turbulence. Laboratory experiments were conducted to determine the rate and circumstance of saturation, i.e. stroke insufficiency. A 1024-actuator 1.5-um-stroke MEMS device was empirically tested with software Kolmogorov-turbulence screens of r_0=10-15cm. The MEMS when solitary suffered saturation ~4% of the time. Simulating a woofer DM with ~5-10 actuators across a 5-m primary mitigated MEMS saturation occurrence to a fraction of a percent. While no adjacent actuators were saturated at opposing positions, mid-to-high-spatial-frequency stroke did saturate more frequently than expected, implying that correlations through the influence functions are important. Analytical models underpredict the stroke requirements, so empirical studies are important.

  13. Active control of adaptive optics system in a large segmented mirror telescope

    NASA Astrophysics Data System (ADS)

    Nagashima, M.; Agrawal, B. N.

    2014-02-01

    For a large adaptive optics system such as a large segmented mirror telescope (SMT), it is often difficult, although not impossible, to directly apply common multi-input multi-output (MIMO) controller design methods due to the computational burden imposed by the large dimension of the system model. In this article, a practical controller design method is proposed which significantly reduces the system dimension for a system where the dimension required to represent the dynamics of the plant is much smaller than the dimension of the full plant model. The proposed method decouples the dynamic and static parts of the plant model by a modal decomposition technique to separately design a controller for each part. Two controllers are then combined using the so-called sensitivity decoupling method so that the resulting feedback loop becomes the superposition of the two individual feedback loops of the dynamic and static parts. A MIMO controller was designed by the proposed method using the H ∞ loop-shaping technique for an SMT model to be compared with other controllers proposed in the literature. Frequency-domain analysis and time-domain simulation results show the superior performance of the proposed controller.

  14. Dynamic performance of MEMS deformable mirrors for use in an active/adaptive two-photon microscope

    NASA Astrophysics Data System (ADS)

    Zhang, Christian C.; Foster, Warren B.; Downey, Ryan D.; Arrasmith, Christopher L.; Dickensheets, David L.

    2016-03-01

    Active optics can facilitate two-photon microscopic imaging deep in tissue. We are investigating fast focus control mirrors used in concert with an aberration correction mirror to control the axial position of focus and system aberrations dynamically during scanning. With an adaptive training step, sample-induced aberrations may be compensated as well. If sufficiently fast and precise, active optics may be able to compensate under-corrected imaging optics as well as sample aberrations to maintain diffraction-limited performance throughout the field of view. Toward this end we have measured a Boston Micromachines Corporation Multi-DM 140 element deformable mirror, and a Revibro Optics electrostatic 4-zone focus control mirror to characterize dynamic performance. Tests for the Multi-DM included both step response and sinusoidal frequency sweeps of specific Zernike modes. For the step response we measured 10%-90% rise times for the target Zernike amplitude, and wavefront rms error settling times. Frequency sweeps identified the 3dB bandwidth of the mirror when attempting to follow a sinusoidal amplitude trajectory for a specific Zernike mode. For five tested Zernike modes (defocus, spherical aberration, coma, astigmatism and trefoil) we find error settling times for mode amplitudes up to 400nm to be less than 52 us, and 3 dB frequencies range from 6.5 kHz to 10 kHz. The Revibro Optics mirror was tested for step response only, with error settling time of 80 μs for a large 3 um defocus step, and settling time of only 18 μs for a 400nm spherical aberration step. These response speeds are sufficient for intra-scan correction at scan rates typical of two-photon microscopy.

  15. Robust Wave-front Correction in a Small Scale Adaptive Optics System Using a Membrane Deformable Mirror

    NASA Astrophysics Data System (ADS)

    Choi, Y.; Park, S.; Baik, S.; Jung, J.; Lee, S.; Yoo, J.

    A small scale laboratory adaptive optics system using a Shack-Hartmann wave-front sensor (WFS) and a membrane deformable mirror (DM) has been built for robust image acquisition. In this study, an adaptive limited control technique is adopted to maintain the long-term correction stability of an adaptive optics system. To prevent the waste of dynamic correction range for correcting small residual wave-front distortions which are inefficient to correct, the built system tries to limit wave-front correction when a similar small difference wave-front pattern is repeatedly generated. Also, the effect of mechanical distortion in an adaptive optics system is studied and a pre-recognition method for the distortion is devised to prevent low-performance system operation. A confirmation process for a balanced work assignment among deformable mirror (DM) actuators is adopted for the pre-recognition. The corrected experimental results obtained by using a built small scale adaptive optics system are described in this paper.

  16. On the optimal reconstruction and control of adaptive optical systems with mirror dynamics.

    PubMed

    Correia, Carlos; Raynaud, Henri-François; Kulcsár, Caroline; Conan, Jean-Marc

    2010-02-01

    In adaptive optics (AO) the deformable mirror (DM) dynamics are usually neglected because, in general, the DM can be considered infinitely fast. Such assumption may no longer apply for the upcoming Extremely Large Telescopes (ELTs) with DM that are several meters in diameter with slow and/or resonant responses. For such systems an important challenge is to design an optimal regulator minimizing the variance of the residual phase. In this contribution, the general optimal minimum-variance (MV) solution to the full dynamical reconstruction and control problem of AO systems (AOSs) is established. It can be looked upon as the parent solution from which simpler (used hitherto) suboptimal solutions can be derived as special cases. These include either partial DM-dynamics-free solutions or solutions derived from the static minimum-variance reconstruction (where both atmospheric disturbance and DM dynamics are neglected altogether). Based on a continuous stochastic model of the disturbance, a state-space approach is developed that yields a fully optimal MV solution in the form of a discrete-time linear-quadratic-Gaussian (LQG) regulator design. From this LQG standpoint, the control-oriented state-space model allows one to (1) derive the optimal state-feedback linear regulator and (2) evaluate the performance of both the optimal and the sub-optimal solutions. Performance results are given for weakly damped second-order oscillatory DMs with large-amplitude resonant responses, in conditions representative of an ELT AO system. The highly energetic optical disturbance caused on the tip/tilt (TT) modes by the wind buffeting is considered. Results show that resonant responses are correctly handled with the MV regulator developed here. The use of sub-optimal regulators results in prohibitive performance losses in terms of residual variance; in addition, the closed-loop system may become unstable for resonant frequencies in the range of interest. PMID:20126246

  17. ESPA: EELV secondary payload adapter with whole-spacecraft isolation for primary and secondary payloads

    NASA Astrophysics Data System (ADS)

    Maly, Joseph R.; Haskett, Scott A.; Wilke, Paul S.; Fowler, E. C.; Sciulli, Dino; Meink, Troy E.

    2000-04-01

    ESPA, the Secondary Payload Adapter for Evolved Expendable Launch Vehicles, addresses two of the major problems currently facing the launch industry: the vibration environment of launch vehicles, and the high cost of putting satellites into orbit. (1) During the 1990s, billions of dollars have been lost due to satellite malfunctions, resulting in total or partial mission failure, which can be directly attributed to vibration loads experienced by payloads during launch. Flight data from several recent launches have shown that whole- spacecraft launch isolation is an excellent solution to this problem. (2) Despite growing worldwide interest in small satellites, launch costs continue to hinder the full exploitation of small satellite technology. Many small satellite users are faced with shrinking budgets, limiting the scope of what can be considered an 'affordable' launch opportunity.

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

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

    Ammons, S. Mark; Hart, Michael; Coughenour, Blake; Romeo, Robert; Martin, Robert; Rademacher, Matt

    2011-10-01

    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 ~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.

  20. Adaptive non-collinear autocorrelation of few-cycle pulses with an angular tunable bi-mirror

    NASA Astrophysics Data System (ADS)

    Treffer, A.; Brunne, J.; Bock, M.; König, S.; Wallrabe, U.; Grunwald, R.

    2016-02-01

    Adaptive autocorrelation with an angular tunable micro-electro-mechanical system is reported. A piezo-actuated Fresnel bi-mirror structure was applied to measure the second order autocorrelation of near-infrared few-cycle laser pulses in a non-collinear setup at tunable superposition angles. Because of enabling measurements with variable scaling and minimizing the influence of distortions by adaptive self-reconstruction, the approach extends the capability of autocorrelators. Flexible scaling and robustness against localized amplitude obscurations are demonstrated. The adaptive reconstruction of temporal frequency information by the Fourier analysis of autocorrelation data is shown. Experimental results and numerical simulations of the beam propagation and interference are compared for variable angles.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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 (ELTs), such as ELT Adaptive optics for GaLaxy Evolution (EAGLE), many challenges remain. Here we investigate requirements that MOAO operation places on deformable mirrors (DMs) using a full end-to-end Monte Carlo adaptive optics (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 μm desired) and provide tolerances for the DM alignment accuracy, both lateral (to within an eighth of a sub-aperture) and rotational (to within 0.2°). By presenting results over a range of laser guide star asterism diameters, we ensure that these results are equally applicable for laser tomographic AO systems. We provide the opportunity for significant cost savings to be made in the implementation of MOAO systems, resulting from the lower requirement for DM actuator density.

  2. Simultaneous and independent adaptive correction of spherical and chromatic aberration using an electron mirror and lens combination.

    PubMed

    Fitzgerald, J P S; Word, R C; Könenkamp, R

    2012-04-01

    We present a theoretical analysis of an electrostatic triode mirror combined with an einzel lens for the correction of spherical and chromatic aberration. We show that this device adaptively corrects spherical and chromatic aberration simultaneously and independently. Chromatic aberration can be compensated over a relative range of -38% to +100%, and spherical aberration over ±100% range. We compare the analytic calculation with a numerical simulation and show that the two descriptions agree to within 5% in the relevant operating regime of the device. PMID:22459116

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

    NASA Astrophysics Data System (ADS)

    Gavel, Donald; Norton, Andrew

    2014-08-01

    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 others 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.

  4. Adaptive optics with a magnetic deformable mirror: applications in the human eye

    NASA Astrophysics Data System (ADS)

    Fernandez, Enrique J.; Vabre, Laurent; Hermann, Boris; Unterhuber, Angelika; Povazay, Boris; Drexler, Wolfgang

    2006-10-01

    A novel deformable mirror using 52 independent magnetic actuators (MIRAO 52, Imagine Eyes) is presented and characterized for ophthalmic applications. The capabilities of the device to reproduce different surfaces, in particular Zernike polynomials up to the fifth order, are investigated in detail. The study of the influence functions of the deformable mirror reveals a significant linear response with the applied voltage. The correcting device also presents a high fidelity in the generation of surfaces. The ranges of production of Zernike polynomials fully cover those typically found in the human eye, even for the cases of highly aberrated eyes. Data from keratoconic eyes are confronted with the obtained ranges, showing that the deformable mirror is able to compensate for these strong aberrations. Ocular aberration correction with polychromatic light, using a near Gaussian spectrum of 130 nm full width at half maximum centered at 800 nm, in five subjects is accomplished by simultaneously using the deformable mirror and an achromatizing lens, in order to compensate for the monochromatic and chromatic aberrations, respectively. Results from living eyes, including one exhibiting 4.66 D of myopia and a near pathologic cornea with notable high order aberrations, show a practically perfect aberration correction. Benefits and applications of simultaneous monochromatic and chromatic aberration correction are finally discussed in the context of retinal imaging and vision.

  5. Discharge conditions in Hall thrusters: secondary electrons emission yield and magnetic mirror influence

    NASA Astrophysics Data System (ADS)

    Miedzik, J.; Daniłko, D.

    2014-11-01

    One dimensional model of plasma bound by two nonconducting walls in external magnetic and electric field is developed. In particular it is designed to describe plasma in Hall thrusters. Combination of Particle-in-cell method with guiding centre approximation of electrons motion allows for kinetic description in short computational time. Comparison of plasma parameters done for two different secondary electrons emission profiles reveals insignificant influence of wall material on the condition in one dimensional model.

  6. Aberration correction in double-pass amplifiers through the use of phase-conjugate mirrors and/or adaptive optics

    NASA Astrophysics Data System (ADS)

    Jackel, Steven M.; Moshe, Inon; Lavi, Raphael

    2001-04-01

    Corrrection of birefringence induced effects (depolarization and bipolar focusing) was achieved in double-pass amplifiers using a Faraday rotator placed between the laser rod and the retroreflecting optic. A necessary condition was that each ray in the beam retraced its path through the amplifying medium. Retrace was limited by imperfect conjugate-beam fidelity and by nonreciprocal double-pass indices of refraction. We compare various retroreflectors: stimulated Brillouin scatter phase-conjugate-mirrors (PCMs), PCMs with relay lenses to image the rod principal plane onto the PCM entrance aperture (IPCMs), IPCMs with external, adaptively-adjusted, astigmatism-correcting cylindrical doublets, and all adaptive optics imaging variable-radius-mirrors (IVRMs). Results with flashlamp pumped, Nd:Cr:GSGG double-pass amplifiers show that average output power increased fivefold with a Faraday rotator plus complete nonlinear optics retroreflector package (IPCM+cylindrical zoom), and that this represents an 80% increase over the power achieved using just a PCM. Far better results are, however, achieved with an IVRM.

  7. Low order adaptive optics on Z-Beamlet using a single actuator deformable mirror

    NASA Astrophysics Data System (ADS)

    Schwarz, Jens; Ramsey, Marc; Smith, Ian; Headley, Daniel; Porter, John

    2006-08-01

    The Z-Beamlet laser at Sandia National Laboratories can perform a full system shot every 3-4 h. This shot rate is limited by thermal aberrations that result from the flashlamp pumped Nd:phosphate amplifier slabs. The lowest order as well as the strongest aberration is of cylindrical shape. Therefore, a single actuator deformable mirror assembly for correction of cylindrical aberration was developed. Mirror performance was modeled using finite element analysis and showed good agreement with derived analytical expressions. Quantitative measurements were performed with an interferometer and thermal lens compensation was achieved in the Z-Beamlet laser system leading to an increased shot rate of one in every 2 h.

  8. Enabling technologies for visible adaptive optics: the Magellan adaptive secondary VisAO camera

    NASA Astrophysics Data System (ADS)

    Kopon, Derek; Males, Jared; Close, Laird M.; Gasho, Victor

    2009-08-01

    Since its beginnings, diffraction-limited ground-based adaptive optics (AO) imaging has been limited to wavelengths in the near IR (λ>1μm) and longer. Visible AO (λ>1μm) has proven to be difficult because shorter wavelengths require wavefront correction on very short spatial and temporal scales. The pupil must be sampled very finely, which requires dense actuator spacing and fine wavefront sampling with large dynamic range. In addition, atmospheric dispersion is much more significant in the visible than in the near-IR. Imaging over a broad visible band requires a very good Atmospheric Dispersion Corrector (ADC). Even with these technologies, our AO simulations using the CAOS code, combined with the optical and site parameters for the 6.5m Magellan telescope, demonstrate a large temporal variability of visible (λ=0.7μm) Strehl on timescales of 50 ms. Over several hundred milliseconds, the visible Strehl can be as high at 50% and as low as 10%. Taking advantage of periods of high Strehl requires either the ability to read out the CCD very fast, thereby introducing significant amounts of read-noise, or the use of a fast asynchronous shutter that can block the low-Strehl light. Our Magellan VisAO camera will use an advanced ADC, a high-speed shutter, and our 585 actuator adaptive secondary to achieve broadband (0.5-1.0 μm) diffraction limited images on the 6.5m Magellan Clay telescope in Chile at Las Campanas Observatory. These will be the sharpest and deepest visible direct images taken to date with a resolution of 17 mas, a factor of 2.7 better than the diffraction limit of the Hubble Space Telescope.

  9. A Theory of Secondary Teachers' Adaptations When Implementing a Reading Intervention Program

    ERIC Educational Resources Information Center

    Leko, Melinda M.; Roberts, Carly A.; Pek, Yvonne

    2015-01-01

    This study examined the causes and consequences of secondary teachers' adaptations when implementing a research-based reading intervention program. Interview, observation, and artifact data were collected on five middle school intervention teachers, leading to a grounded theory composed of the core component, reconciliation through adaptation, and…

  10. Pupil Adaptation to Secondary School. Publication No. 18.

    ERIC Educational Resources Information Center

    Spelman, B. J.

    The educational and social adjustment of Irish schoolchildren as they transfer to new schools is explored. The study emphasized problems of students entering secondary schools after completing primary school. Conducted by the Northern Ireland Council for Educational Research, the study encompassed over 3000 children who transferred from primary to…

  11. Simulations of far-field optical beam quality influenced by the thermal distortion of the secondary mirror for high-power laser system

    NASA Astrophysics Data System (ADS)

    Guo, Ruhai; Chen, Ning; Zhuang, Xinyu; Wang, Bing

    2015-02-01

    In order to research the influence on the beam quality due to thermal deformation of the secondary mirror in the high power laser system, the theoretical simulation study is performed. Firstly, three typical laser power 10kW, 50kW and 100kW with the wavelength 1.064μm are selected to analyze thermal deformation of mirror through the finite element analyze of thermodynamics instantaneous method. Then the wavefront aberration can be calculated by ray-tracing theory. Finally, focus spot radius,beam quality (BQ) of far-filed beam can be calculated and comparably analyzed by Fresnel diffraction integration. The simulation results show that with the increasing laser power, the optical aberration of beam director gets worse, the far-field optical beam quality decrease, which makes the laser focus spot broadening and the peak optical intensity of center decreasing dramatically. Comparing the clamping ring and the three-point clamping, the former is better than the latter because the former only induces the rotation symmetric deformation and the latter introduces additional astigmatism. The far-field optical beam quality can be improved partly by simply adjusting the distance between the main mirror and the secondary mirror. But the far-field power density is still the one tenth as that without the heat distortion of secondary mirror. These results can also provide the reference to the thermal aberration analyze for high power laser system and can be applied to the field of laser communication system and laser weapon etc.

  12. EUV reflectance characterization of the 94/304 ? flight secondary AIA mirror at beamline 6.3.2 of the Advanced Light Source

    SciTech Connect

    Soufli, R; Spiller, E; Aquila, A L; Gullikson, E M; Windt, D L

    2006-02-22

    The AIA secondary flight mirror, previously coated at Columbia University with Mg/SiC for the 303.8 {angstrom} channel and Mo/Y for the 93.9 {angstrom} channel was characterized by means of EUV reflectance measurements at beamline 6.3.2 of the Advanced Light Source (ALS) synchrotron at LBNL on January 10, 2006. Paul Boerner (LMSAL) also participated in these measurements.

  13. Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer

    PubMed Central

    Stokkan, Karl-Arne; Folkow, Lars; Dukes, Juliet; Neveu, Magella; Hogg, Chris; Siefken, Sandra; Dakin, Steven C.; Jeffery, Glen

    2013-01-01

    Arctic reindeer experience extreme changes in environmental light from continuous summer daylight to continuous winter darkness. Here, we show that they may have a unique mechanism to cope with winter darkness by changing the wavelength reflection from their tapetum lucidum (TL). In summer, it is golden with most light reflected back directly through the retina, whereas in winter it is deep blue with less light reflected out of the eye. The blue reflection in winter is associated with significantly increased retinal sensitivity compared with summer animals. The wavelength of reflection depends on TL collagen spacing, with reduced spacing resulting in shorter wavelengths, which we confirmed in summer and winter animals. Winter animals have significantly increased intra-ocular pressure, probably produced by permanent pupil dilation blocking ocular drainage. This may explain the collagen compression. The resulting shift to a blue reflection may scatter light through photoreceptors rather than directly reflecting it, resulting in elevated retinal sensitivity via increased photon capture. This is, to our knowledge, the first description of a retinal structural adaptation to seasonal changes in environmental light. Increased sensitivity occurs at the cost of reduced acuity, but may be an important adaptation in reindeer to detect moving predators in the dark Arctic winter. PMID:24174115

  14. Selective and non-selective deposition of thick polysilicon layers for adaptive mirror device

    NASA Astrophysics Data System (ADS)

    Bartek, M.; Vdovin, G. V.; Wolffenbuttel, R. F.

    1997-09-01

    Two IC-process-compatible fabrication schemes, based on the selective and non-selective deposition of a thick polysilicon layer in an epitaxial reactor, are used for adaptive micromirror device fabrication. The micromirror consists of a composite diaphragm (a 0960-1317/7/3/014/img1 square-shaped silicon nitride membrane on which an additional 0960-1317/7/3/014/img2 thick polycrystalline silicon layer with a circular aperture is formed) coated with a 0960-1317/7/3/014/img3 reflective aluminium layer on a bulk micromachined 10.5 mm by 10.5 mm square silicon frame. The additional polycrystalline silicon layer with a circular aperture improves the optical properties of a deflected square-shaped silicon nitride membrane resulting from anisotropic KOH etching.

  15. Point Spread Function and Transmittance Analyses for Conical and Hexapod Secondary Mirror Support Towers for the Next Generation Space Telescope (NGST)

    NASA Technical Reports Server (NTRS)

    Wilkerson, Gary W.; Pitalo, Stephen K.

    1999-01-01

    Different secondary mirror support towers were modeled on the CODE V optical design/analysis program for the NGST Optical Telescope Assembly (OTA) B. The vertices of the NGST OTA B primary and secondary mirrors were separated by close to 9.0 m. One type of tower consisted of a hollow cone 6.0 m long, 2.00 m in diameter at the base, and 0.704 m in diameter at its top. The base of the cone was considered attached to the primary's reaction structure through a hole in the primary. Extending up parallel to the optical axis from the top of this cylinder were eight blades (pyramidal struts) 3.0 m long. A cross section of each these long blades was an isosceles triangle with a base of 0.010 m and a height of 0.100 m with the sharpest part of each triangle pointing inward. The eight struts occurred every 45 deg. The other type of tower was purely a hexapod arrangement and had no blades or cones. The hexapod consisted simply of six, very thin, circular struts, leaving in pairs at 12:00, 4:00, and 8:00 at the primary and traversing to the outer edge of the back of the secondary mount. At this mount, two struts arrived at each of 10:00, 2:00, and 6:00. The struts were attached to the primary mirror in a ring 3.5 m in diameter. They reached the back of the secondary mount, a circle 0.704 m in diameter. Transmittance analyses at two levels were performed on the secondary mirror support towers. Detailed transmittances were accomplished by the use of the CODE V optical design/analysis program and were compared to transmittance calculations that were almost back-of-the-envelope. Point spread function (PSF) calculations, including both diffraction and aberration effects, were performed on CODE V. As one goes out from the center of the blur (for a point source), the two types of support towers showed little difference between their PSF intensities until one reaches about the 3% level. Contours can be delineated on CODE V down to about 10 (exp -8) times the peak intensity, fine

  16. The Experience of Male Adolescent Refugees during Their Transfer and Adaptation to a UK Secondary School

    ERIC Educational Resources Information Center

    Hastings, Catherine

    2012-01-01

    This paper outlines a study which investigated the experience of six male adolescent refugees during their transfer and adaptation to a secondary school in the UK. The research used a qualitative design. The approach adopted was Interpretative Phenomenological Analysis. The data generated three superordinate themes which reflected the…

  17. Design and development of a 329-segment tip-tilt piston mirror array for space-based adaptive optics

    NASA Astrophysics Data System (ADS)

    Stewart, Jason B.; Bifano, Thomas G.; Bierden, Paul; Cornelissen, Steven; Cook, Timothy; Levine, B. Martin

    2006-01-01

    We report on the development of a new MEMS deformable mirror (DM) system for the hyper-contrast visible nulling coronagraph architecture designed by the Jet Propulsion Laboratory for NASA's Terrestrial Planet Finding (TPF) mission. The new DM is based largely upon existing lightweight, low power MEMS DM technology at Boston University (BU), tailored to the rigorous optical and mechanical requirements of the nulling coronagraph. It consists of 329-hexagonal segments on a 600μm pitch, each with tip/tilt and piston degrees of freedom. The mirror segments have 1μm of stroke, a tip/tilt range of 600 arc-seconds, and maintain their figure to within 2nm RMS under actuation. The polished polycrystalline silicon mirror segments have a surface roughness of 5nm RMS and an average curvature of 270mm. Designing a mirror segment that maintains its figure during actuation was a very significant challenge faced during DM development. Two design concepts were pursued in parallel to address this challenge. The first design uses a thick, epitaxial grown polysilicon mirror layer to add rigidity to the mirror segment. The second design reduces mirror surface bending by decoupling actuator diaphragm motion from the mirror surface motion. This is done using flexure cuts around the mirror post in the actuator diaphragm. Both DM architectures and their polysilicon microfabrication process are presented. Recent optical and electromechanical characterization results will also be discussed, in addition to plans for further improvement of DM figure to satisfy nulling coronagraph optical requirements.

  18. Mesmerising mirror neurons.

    PubMed

    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. PMID:20167276

  19. IIR filtering based adaptive active vibration control methodology with online secondary path modeling using PZT actuators

    NASA Astrophysics Data System (ADS)

    Boz, Utku; Basdogan, Ipek

    2015-12-01

    Structural vibrations is a major cause for noise problems, discomfort and mechanical failures in aerospace, automotive and marine systems, which are mainly composed of plate-like structures. In order to reduce structural vibrations on these structures, active vibration control (AVC) is an effective approach. Adaptive filtering methodologies are preferred in AVC due to their ability to adjust themselves for varying dynamics of the structure during the operation. The filtered-X LMS (FXLMS) algorithm is a simple adaptive filtering algorithm widely implemented in active control applications. Proper implementation of FXLMS requires availability of a reference signal to mimic the disturbance and model of the dynamics between the control actuator and the error sensor, namely the secondary path. However, the controller output could interfere with the reference signal and the secondary path dynamics may change during the operation. This interference problem can be resolved by using an infinite impulse response (IIR) filter which considers feedback of the one or more previous control signals to the controller output and the changing secondary path dynamics can be updated using an online modeling technique. In this paper, IIR filtering based filtered-U LMS (FULMS) controller is combined with online secondary path modeling algorithm to suppress the vibrations of a plate-like structure. The results are validated through numerical and experimental studies. The results show that the FULMS with online secondary path modeling approach has more vibration rejection capabilities with higher convergence rate than the FXLMS counterpart.

  20. Transferred and Adapted Models of Secondary Education in Ghana: What Implications for National Development?

    NASA Astrophysics Data System (ADS)

    Quist, Hubert O.

    2003-09-01

    The secondary-education models implemented in Ghana since colonial times constitute a classic case of "educational transfer and adaptation". Transferred from England, and in recent years the United States of America and Japan, these models have had a significant impact on Ghana's development in diverse ways. Yet educational research on Ghana has under-recognized this important issue of "educational transfer and adaptation", especially the relationship between these transferred models and national development. This study addresses such neglect by first focusing on those institutions that served as prototypes. Second, it appraises the models pointing out their implications for national development. It is contended that the foreign models that were adapted (indigenised) have been significant instruments for the human- resource and socio-political development of Ghana. However, their emphasis on the academic type of education ultimately has tended to create a situation of dependency particularly with respect to techno-scientific and economic development.

  1. Performance evaluation of coherent free space optical communications with a double-stage fast-steering-mirror adaptive optics system depending on the Greenwood frequency.

    PubMed

    Liu, Wei; Yao, Kainan; Huang, Danian; Lin, Xudong; Wang, Liang; Lv, Yaowen

    2016-06-13

    The Greenwood frequency (GF) is influential in performance improvement for the coherent free space optical communications (CFSOC) system with a closed-loop adaptive optics (AO) unit. We analyze the impact of tilt and high-order aberrations on the mixing efficiency (ME) and bit-error-rate (BER) under different GF. The root-mean-square value (RMS) of the ME related to the RMS of the tilt aberrations, and the GF is derived to estimate the volatility of the ME. Furthermore, a numerical simulation is applied to verify the theoretical analysis, and an experimental correction system is designed with a double-stage fast-steering-mirror and a 97-element continuous surface deformable mirror. The conclusions of this paper provide a reference for designing the AO system for the CFSOC system. PMID:27410346

  2. Adaptive Flexibility of Oldowan Hominins: Secondary Use of Flakes at Bizat Ruhama, Israel

    PubMed Central

    Zaidner, Yossi

    2013-01-01

    The lithic assemblage of the Early Pleistocene site of Bizat Ruhama, Israel demonstrates the earliest evidence for systematic secondary knapping of flakes. The site, dated to the Matuyama chron, is one of the earliest primary context Oldowan occurrences in Eurasia. According to the experimental replication of the stone-tool production sequence, the secondary knapping of flakes was a part of a multi-stage operational sequence targeted at the production of small (<2 cm) flakes. This sequence included four stages: acquisition of chert pebbles, production of flakes, deliberate selection of flakes of specific morphologies, and their secondary knapping by free-hand or bipolar methods. The results suggest that flakes with retouch-like scars that were produced during this sequence and which commonly are interpreted as shaped tools are unintentional waste products of the small flake production. The intentional manufacture of very small flakes at Bizat Ruhama was probably an economic response to the raw material constrains. Systematic secondary knapping of flakes has not yet been reported from other Early Pleistocene sites. Systematic secondary knapping for small flake production became increasingly important only in the lithic industries of the second half of the Middle Pleistocene, almost a million years later. The results from Bizat Ruhama indicate that Oldowan stone-tool production sequence was conceptually more complex than previously suggested and offer a new perspective on the capabilities for invention and the adaptive flexibility of the Oldowan hominins. PMID:23840539

  3. Contactless Large Deformable Mirrors: ELT AO corrector technology available now

    NASA Astrophysics Data System (ADS)

    Biasi, Roberto; Gallieni, Daniele

    2011-09-01

    We present our design of ESO E-ELT M4 deformable mirror and GMT Adaptive Secondary Mirrors unit. Both systems are based on our consolidated design of large deformable mirrors for 8-m class telescopes, successfully implemented on MMT and LBT and currently in advanced construction and testing phase for VLT and Magellan telescopes respectively. We describe the main features of the technology adopted: thin Zerodur mirror shell with contactless voice coil motors, co-located capacitive sensors to close a local position loop at each actuator, centralized control by force feedforward, embedded real time control and communication electronics. We then highlight how the same concept has been scaled up on the E-ELT M4AU and the GMT-ASM cases, adapting the technology to deal with thousands of actuators, while maintaining its intrinsic advantages: tolerance to actuators' failures, mechanical de-coupling and relaxed tolerances between correcting mirror and reference structure, large stroke, hysteresis-free behavior. For the next generation systems, we report the predicted performances based on the actual results attained on our 1-m class DMs currently in use: the LBT adaptive secondary for the GMT-ASM and the 330 actuators Demonstration Prototype for the E-ELT M4AU.

  4. Virtual Mirrors

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2010-01-01

    The multiple-reflection photograph in Fig. 1 was taken in an elevator on board the cruise ship Norwegian Jade in March 2008. Three of the four walls of the elevator were mirrored, allowing me to see the combination of two standard arrangements of plane mirrors: two mirrors set at 90 degrees to each other and two parallel mirrors. Optical phenomena…

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

    PubMed

    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. PMID:18253168

  6. Metabolic modelling reveals the specialization of secondary replicons for niche adaptation in Sinorhizobium meliloti.

    PubMed

    diCenzo, George C; Checcucci, Alice; Bazzicalupo, Marco; Mengoni, Alessio; Viti, Carlo; Dziewit, Lukasz; Finan, Turlough M; Galardini, Marco; Fondi, Marco

    2016-01-01

    The genome of about 10% of bacterial species is divided among two or more large chromosome-sized replicons. The contribution of each replicon to the microbial life cycle (for example, environmental adaptations and/or niche switching) remains unclear. Here we report a genome-scale metabolic model of the legume symbiont Sinorhizobium meliloti that is integrated with carbon utilization data for 1,500 genes with 192 carbon substrates. Growth of S. meliloti is modelled in three ecological niches (bulk soil, rhizosphere and nodule) with a focus on the role of each of its three replicons. We observe clear metabolic differences during growth in the tested ecological niches and an overall reprogramming following niche switching. In silico examination of the inferred fitness of gene deletion mutants suggests that secondary replicons evolved to fulfil a specialized function, particularly host-associated niche adaptation. Thus, genes on secondary replicons might potentially be manipulated to promote or suppress host interactions for biotechnological purposes. PMID:27447951

  7. Metabolic modelling reveals the specialization of secondary replicons for niche adaptation in Sinorhizobium meliloti

    PubMed Central

    diCenzo, George C.; Checcucci, Alice; Bazzicalupo, Marco; Mengoni, Alessio; Viti, Carlo; Dziewit, Lukasz; Finan, Turlough M.; Galardini, Marco; Fondi, Marco

    2016-01-01

    The genome of about 10% of bacterial species is divided among two or more large chromosome-sized replicons. The contribution of each replicon to the microbial life cycle (for example, environmental adaptations and/or niche switching) remains unclear. Here we report a genome-scale metabolic model of the legume symbiont Sinorhizobium meliloti that is integrated with carbon utilization data for 1,500 genes with 192 carbon substrates. Growth of S. meliloti is modelled in three ecological niches (bulk soil, rhizosphere and nodule) with a focus on the role of each of its three replicons. We observe clear metabolic differences during growth in the tested ecological niches and an overall reprogramming following niche switching. In silico examination of the inferred fitness of gene deletion mutants suggests that secondary replicons evolved to fulfil a specialized function, particularly host-associated niche adaptation. Thus, genes on secondary replicons might potentially be manipulated to promote or suppress host interactions for biotechnological purposes. PMID:27447951

  8. Investigating the adaptive immune response in influenza and secondary bacterial pneumonia and nanoparticle based therapeutic delivery

    NASA Astrophysics Data System (ADS)

    Chakravarthy, Krishnan V.

    In early 2000, influenza and its associated complications were the 7 th leading cause of death in the United States[1-4]. As of today, this major health problem has become even more of a concern, with the possibility of a potentially devastating avian flu (H5N1) or swine flu pandemic (H1N1). According to the Centers for Disease Control (CDC), over 10 countries have reported transmission of influenza A (H5N1) virus to humans as of June 2006 [5]. In response to this growing concern, the United States pledged over $334 million dollars in international aid for battling influenza[1-4]. The major flu pandemic of the early 1900's provided the first evidence that secondary bacterial pneumonia (not primary viral pneumonia) was the major cause of death in both community and hospital-based settings. Secondary bacterial infections currently account for 35-40% mortality following a primary influenza viral infection [1, 6]. The first component of this work addresses the immunological mechanisms that predispose patients to secondary bacterial infections following a primary influenza viral infection. By assessing host immune responses through various immune-modulatory tools, such as use of volatile anesthetics (i.e. halothane) and Apilimod/STA-5326 (an IL-12/Il-23 transcription blocker), we provide experimental evidence that demonstrates that the overactive adaptive Th1 immune response is critical in mediating increased susceptibility to secondary bacterial infections. We also present data that shows that suppressing the adaptive Th1 immune response enhances innate immunity, specifically in alveolar macrophages, by favoring a pro anti-bacterial phenotype. The second component of this work addresses the use of nanotechnology to deliver therapeutic modalities that affect the primary viral and associated secondary bacterial infections post influenza. First, we used surface functionalized quantum dots for selective targeting of lung alveolar macrophages both in vitro and in vivo

  9. Using an active primary surface to correct for low-order manufacturing errors in secondary mirrors of large reflector antennas

    NASA Astrophysics Data System (ADS)

    Cortes-Medellin, German; Lovell, Amy J.; Enriquez, Rogerio; Smith, David R.

    2004-09-01

    In the fabrication of high-performance, low-cost secondary reflectors for radio telescopes, it is a significant challenge to avoid introduction of low-order surface errors such as astigmatism or coma. This arises primarily because low-order surface errors are easily induced by support structure placement or simple thermal variations in the manufacturing process. It is, of course, possible to bring these errors to within the required tolerance, but if an active primary reflector is present, it may be possible to relax the requirements on the secondary and perhaps lower its cost. In this paper, we take the Large Millimeter-wave Telescope (LMT/GTM) as an example system. We model the effects of correcting a deformed sub-reflector by using the existing segmented active primary. The sub-reflector deformation patterns employed are low-order (e.g., astigmatism or coma), but are allowed significant excursions from the nominal surface figure. For each case, we demonstrate the best theoretical performance, using the active primary to correct for the errors. Additionally, to determine whether such an approach would be practical, we also demonstrate the likely performance improvement that could be achieved using brief measurements on an astronomical source. In this approach, we introduce varying amounts of known low-order deformation patterns into the active primary and seek the combination that results in the maximum signal. Finally, we compare this result to the theoretical maximum and make recommendations on the practical utility of the approach.

  10. An Adaptive Defect Weighted Sampling Algorithm to Design Pseudoknotted RNA Secondary Structures.

    PubMed

    Zandi, Kasra; Butler, Gregory; Kharma, Nawwaf

    2016-01-01

    Computational design of RNA sequences that fold into targeted secondary structures has many applications in biomedicine, nanotechnology and synthetic biology. An RNA molecule is made of different types of secondary structure elements and an important RNA element named pseudoknot plays a key role in stabilizing the functional form of the molecule. However, due to the computational complexities associated with characterizing pseudoknotted RNA structures, most of the existing RNA sequence designer algorithms generally ignore this important structural element and therefore limit their applications. In this paper we present a new algorithm to design RNA sequences for pseudoknotted secondary structures. We use NUPACK as the folding algorithm to compute the equilibrium characteristics of the pseudoknotted RNAs, and describe a new adaptive defect weighted sampling algorithm named Enzymer to design low ensemble defect RNA sequences for targeted secondary structures including pseudoknots. We used a biological data set of 201 pseudoknotted structures from the Pseudobase library to benchmark the performance of our algorithm. We compared the quality characteristics of the RNA sequences we designed by Enzymer with the results obtained from the state of the art MODENA and antaRNA. Our results show our method succeeds more frequently than MODENA and antaRNA do, and generates sequences that have lower ensemble defect, lower probability defect and higher thermostability. Finally by using Enzymer and by constraining the design to a naturally occurring and highly conserved Hammerhead motif, we designed 8 sequences for a pseudoknotted cis-acting Hammerhead ribozyme. Enzymer is available for download at https://bitbucket.org/casraz/enzymer. PMID:27499762

  11. An Adaptive Defect Weighted Sampling Algorithm to Design Pseudoknotted RNA Secondary Structures

    PubMed Central

    Zandi, Kasra; Butler, Gregory; Kharma, Nawwaf

    2016-01-01

    Computational design of RNA sequences that fold into targeted secondary structures has many applications in biomedicine, nanotechnology and synthetic biology. An RNA molecule is made of different types of secondary structure elements and an important RNA element named pseudoknot plays a key role in stabilizing the functional form of the molecule. However, due to the computational complexities associated with characterizing pseudoknotted RNA structures, most of the existing RNA sequence designer algorithms generally ignore this important structural element and therefore limit their applications. In this paper we present a new algorithm to design RNA sequences for pseudoknotted secondary structures. We use NUPACK as the folding algorithm to compute the equilibrium characteristics of the pseudoknotted RNAs, and describe a new adaptive defect weighted sampling algorithm named Enzymer to design low ensemble defect RNA sequences for targeted secondary structures including pseudoknots. We used a biological data set of 201 pseudoknotted structures from the Pseudobase library to benchmark the performance of our algorithm. We compared the quality characteristics of the RNA sequences we designed by Enzymer with the results obtained from the state of the art MODENA and antaRNA. Our results show our method succeeds more frequently than MODENA and antaRNA do, and generates sequences that have lower ensemble defect, lower probability defect and higher thermostability. Finally by using Enzymer and by constraining the design to a naturally occurring and highly conserved Hammerhead motif, we designed 8 sequences for a pseudoknotted cis-acting Hammerhead ribozyme. Enzymer is available for download at https://bitbucket.org/casraz/enzymer. PMID:27499762

  12. Mirror mount

    DOEpatents

    Kuklo, Thomas C.; Bender, Donald A.

    1994-01-01

    A unique lens or mirror mount having adjustable constraints at two key locations to allow for "X" and "Y" tilts of the mirror only. The device uses two pair of flexures of a type such that the pivots of the mirror gimble are rigidly fixed in all planes allowing the device to have zero stacking tolerance and zero wear over time.

  13. Einstein's Mirror

    ERIC Educational Resources Information Center

    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. fMRI Adaptation between Action Observation and Action Execution Reveals Cortical Areas with Mirror Neuron Properties in Human BA 44/45

    PubMed Central

    de la Rosa, Stephan; Schillinger, Frieder L.; Bülthoff, Heinrich H.; Schultz, Johannes; Uludag, Kamil

    2016-01-01

    Mirror neurons (MNs) are considered to be the supporting neural mechanism for action understanding. MNs have been identified in monkey’s area F5. The identification of MNs in the human homolog of monkeys’ area F5 Broadmann Area 44/45 (BA 44/45) has been proven methodologically difficult. Cross-modal functional MRI (fMRI) adaptation studies supporting the existence of MNs restricted their analysis to a priori candidate regions, whereas studies that failed to find evidence used non-object-directed (NDA) actions. We tackled these limitations by using object-directed actions (ODAs) differing only in terms of their object directedness in combination with a cross-modal adaptation paradigm and a whole-brain analysis. Additionally, we tested voxels’ blood oxygenation level-dependent (BOLD) response patterns for several properties previously reported as typical MN response properties. Our results revealed 52 voxels in left inferior frontal gyrus (IFG; particularly BA 44/45), which respond to both motor and visual stimulation and exhibit cross-modal adaptation between the execution and observation of the same action. These results demonstrate that part of human IFG, specifically BA 44/45, has BOLD response characteristics very similar to monkey’s area F5. PMID:26973496

  15. Chiral mirrors

    SciTech Connect

    Plum, Eric; Zheludev, Nikolay I.

    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. Micromachined mirrors

    NASA Astrophysics Data System (ADS)

    Conant, Robert Alan

    This dissertation discusses the fundamental limits of scanning mirror design, focusing on the limitations due to the interaction between mechanical properties (mirror flatness and dynamic deformation), and optical properties (beam divergence and optical resolution). The performance criteria for both resonant-scanning mirrors and steady-state, beam-positioning mirrors are related to the mirror geometries, desired optical resolution, material properties, and mechanical resonant frequencies. The optical resolution of the scanning mirror is linearly dependent on the mirror length, so longer mirrors should provide higher-resolution scanners. However, when undergoing an angular acceleration mirrors exhibit dynamic deformation, which is shown to be proportional to the fifth power of the length. Two different implementations of MEMS scanning mirrors are presented: polysilicon surface-micromachined mirrors and a new design we call the Staggered Torsional Electrostatic Combdrive (STEC) micromirror. The surface-micromachined mirrors are shown to be capable of reliable operation, but they have significant performance limitations caused by the limited thickness obtainable with the LPCVD-polysilicon structures. Calculations show that surface-micromachined mirrors of thickness 1.5 mum and diameter 550 mum are only capable of scanning +/-10 degrees at 251 Hz while retaining diffraction-limited optical performance. The STEC micromirrors, designed to overcome the limitations of the surface-micromachined mirrors, are capable of much higher-speed scanning (up to 61 kHz) without performance-limiting dynamic deformation of the mirror surface. The STEC micromirror fabrication process is extended to create Tensile Optical Surface (TOS) micromirrors---mirrors with thick silicon rib support structures and thin membranes that provide the reflective surface. An application of scanning mirrors is presented: a raster-scanning video display. This demonstration uses two surface

  17. The Athena Mirror

    NASA Astrophysics Data System (ADS)

    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.

  18. High stroke pixel for a deformable mirror

    DOEpatents

    Miles, Robin R.; Papavasiliou, Alexandros P.

    2005-09-20

    A mirror pixel that can be fabricated using standard MEMS methods for a deformable mirror. The pixel is electrostatically actuated and is capable of the high deflections needed for spaced-based mirror applications. In one embodiment, the mirror comprises three layers, a top or mirror layer, a middle layer which consists of flexures, and a comb drive layer, with the flexures of the middle layer attached to the mirror layer and to the comb drive layer. The comb drives are attached to a frame via spring flexures. A number of these mirror pixels can be used to construct a large mirror assembly. The actuator for the mirror pixel may be configured as a crenellated beam with one end fixedly secured, or configured as a scissor jack. The mirror pixels may be used in various applications requiring high stroke adaptive optics.

  19. Mirror mount

    DOEpatents

    Kuklo, T.C.; Bender, D.A.

    1994-10-04

    A unique lens or mirror mount having adjustable constraints at two key locations to allow for ''X'' and ''Y'' tilts of the mirror only is disclosed. The device uses two pair of flexures of a type such that the pivots of the mirror gimble are rigidly fixed in all planes allowing the device to have zero stacking tolerance and zero wear over time. 4 figs.

  20. Hysteresis compensation of the piezoelectric ceramic actuators-based tip/tilt mirror with a neural network method in adaptive optics

    NASA Astrophysics Data System (ADS)

    Wang, Chongchong; Wang, Yukun; Hu, Lifa; Wang, Shaoxin; Cao, Zhaoliang; Mu, Quanquan; Li, Dayu; Yang, Chengliang; Xuan, Li

    2016-05-01

    The intrinsic hysteresis nonlinearity of the piezo-actuators can severely degrade the positioning accuracy of a tip-tilt mirror (TTM) in an adaptive optics system. This paper focuses on compensating this hysteresis nonlinearity by feed-forward linearization with an inverse hysteresis model. This inverse hysteresis model is based on the classical Presiach model, and the neural network (NN) is used to describe the hysteresis loop. In order to apply it in the real-time adaptive correction, an analytical nonlinear function derived from the NN is introduced to compute the inverse hysteresis model output instead of the time-consuming NN simulation process. Experimental results show that the proposed method effectively linearized the TTM behavior with the static hysteresis nonlinearity of TTM reducing from 15.6% to 1.4%. In addition, the tip-tilt tracking experiments using the integrator with and without hysteresis compensation are conducted. The wavefront tip-tilt aberration rejection ability of the TTM control system is significantly improved with the -3 dB error rejection bandwidth increasing from 46 to 62 Hz.

  1. The ADAPTABLE Trial and Aspirin Dosing in Secondary Prevention for Patients with Coronary Artery Disease.

    PubMed

    Johnston, Abigail; Jones, W Schuyler; Hernandez, Adrian F

    2016-08-01

    Coronary artery disease (CAD) is the underlying cause of death in one out of seven deaths in the USA. Aspirin therapy has been proven to decrease mortality and major adverse cardiovascular events in patients with CAD. Despite a plethora of studies showing the benefit of aspirin in secondary prevention of cardiovascular events, debate remains regarding the optimal dose due to relatively small studies that had disparate results when comparing patients taking different aspirin dosages. More recently, aspirin dosing has been thoroughly studied in the CAD population with concomitant therapy (such as P2Y12 inhibitors); however, patients in these studies were not randomized to aspirin dose. No randomized controlled trial has directly measured aspirin dosages in a population of patients with established coronary artery disease. In 2015, the Patient-Centered Outcomes Research Institute (PCORI) developed a network, called PCORnet, that includes patient-powered research networks (PPRN) and clinical data research networks (CDRN). The main objective of PCORnet is to conduct widely generalizable observational studies and clinical trials (including large, pragmatic clinical trials) at a low cost. The first clinical trial, called Aspirin Dosing: A Patient-centric Trial Assessing Benefits and Long-term Effectiveness (ADAPTABLE), will randomly assign 20,000 subjects with established coronary heart disease to either low dose (81 mg) or high dose (325 mg) and should be able to finally answer which dosage of aspirin is best for patients with established cardiovascular disease. PMID:27423939

  2. Impact of Attitudinal Adaptation on Academic Achievement among Students: A Comparative Study of Boys and Girls in Boarding Secondary Schools in Meru County, Kenya

    ERIC Educational Resources Information Center

    Murithi, Grace Gatune; Nyaga, Veronica Karimi; Barchok, Hillary K.

    2015-01-01

    This study sought to examine the impact of attitudinal adaptation on academic achievement among boys and girls in boarding secondary schools in Meru County in Kenya. The descriptive survey research design was adapted for the study whose sample size was 384 students, school counsellors and deputy principals in the boarding secondary schools. The…

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Magic Mirrors

    ERIC Educational Resources Information Center

    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…

  5. Slumped mirrors

    NASA Astrophysics Data System (ADS)

    Pteancu, Mircea; Dragan, Dorin; Dragan, Olivier; Miron, Andrei; Stanescu, Octavian

    2008-02-01

    The authors discusse the construction of slumped mirrors, their fabrication and testing (polishing and lapping). An important topic of the discussion is thermal fabrication of mirrors by using of matrixes. One of the authors of the entry is combining astronomy and aquariums construction.

  6. Einstein's Mirror

    NASA Astrophysics Data System (ADS)

    Gjurchinovski, Aleksandar; Skeparovski, Aleksandar

    2008-10-01

    Reflection of light from a plane mirror in uniform rectilinear motion is a century-old problem, intimately related to the foundations of special relativity.1-4 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 constant velocity.5 Einstein showed an intriguing fact that the usual law of reflection would not hold in the case of a uniformly moving mirror, that is, the angles of incidence and reflection of the light would not equal each other. Later on, it has been shown that the law of reflection at a moving mirror can be obtained in various alternative ways,6-10 but none of them seems suitable for bringing this interesting subject into the high school classroom.

  7. Mirror, Mirror on the Wall...?

    ERIC Educational Resources Information Center

    Pflaster, Gail

    1979-01-01

    The study determined the value of using a mirror for speech teaching by recording manner, place, voicing, and blend errors produced by 27 hearing-impaired children (5-13 years old) while imitating consonant-vowel syllables under three conditions (audition alone, audition plus direct vision, and audition plus vision using a mirror). (Author)

  8. Smart materials optical mirrors

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Rabin, Douglas M.

    2014-08-01

    We report the fabrication of imaging quality optical mirrors with smooth surfaces using carbon nanotubes embedded in an epoxy matrix. CNT/epoxy is a multifunctional or `smart' composite material that has sensing capabilities and can be made to incorporate self-actuation as well. Moreover, since the precursor is a low density liquid, large and lightweight mirrors can be fabricated by processes such as replication, spincasting, and 3D printing. The technology therefore holds promise for development of a new generation of lightweight, compact `smart' telescope mirrors with figure sensing and active or adaptive figure control. We report on measurements made of optical and mechanical characteristics. We discuss possible paths for future development.

  9. Carbon nanotube optical mirrors

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Rabin, Douglas

    2015-01-01

    We report the fabrication of imaging quality optical mirrors with smooth surfaces using carbon nanotubes (CNT) embedded in an epoxy matrix. CNT/epoxy is a multifunctional composite material that has sensing capabilities and can be made to incorporate self-actuation. Moreover, as the precursor is a low density liquid, large and lightweight mirrors can be fabricated by processes such as replication, spincasting, and three-dimensional printing. Therefore, the technology holds promise for the development of a new generation of lightweight, compact "smart" telescope mirrors with figure sensing and active or adaptive figure control. We report on measurements made of optical and mechanical characteristics, active optics experiments, and numerical modeling. We discuss possible paths for future development.

  10. Mirror mount

    DOEpatents

    Humpal, H.H.

    1987-11-10

    A mirror mount is provided that allows free pitch, yaw and roll motion of the mirror while keeping the location of a point on the surface of the mirror fixed in the rest frame of reference of the mount. Yaw movement is provided by two yaw cylinders that are bearing mounted to provide rotation. Pitch and roll motion is provided by a spherically annular shell that is air bearing mounted to move between a clamp and an upper pedestal bearing. The centers of curvature of the spherical surfaces of the shell lie upon the point. Pitch motion and roll motion are separately and independently imparted to mirror by a pair of pitch paddles and a pair of roll paddles that are independently and separately moved by control rods driven by motors. 5 figs.

  11. Mirror mount

    DOEpatents

    Humpal, H.H.

    1986-03-21

    A mirror mount is provided that allows free pitch, yaw and roll motion of the mirror while keeping the location of a point on the surface of the mirror fixed in the rest frame of reference of the mount. Yaw movement is provided by two yaw cylinders that are bearing mounted to provide rotation. Pitch and roll motion is provided by a spherically annular shell that is air bearing mounted to move between a clamp and an upper pedestal bearing. The centers of curvature of the spherical surfaces of the shell lie upon the point. Pitch motion and roll motion are separately and independently imparted to mirror by a pair of pitch paddles and a pair of roll paddles that are independently and separately moved by control rods driven by motors.

  12. Mirror mount

    DOEpatents

    Humpal, Harold H.

    1987-01-01

    A mirror mount (10) is provided that allows free pitch, yaw and roll motion of the mirror (28) while keeping the location of a point (56) on the surface of the mirror (28) fixed in the rest frame of reference of the mount (10). Yaw movement is provided by two yaw cylinders (30,32) that are bearing (52) mounted to provide rotation. Pitch and roll motion is provided by a spherically annular shell (42) that is air bearing (72,74) mounted to move between a clamp (60) and an upper pedestal bearing (44). The centers of curvature of the spherical surfaces of the shell (42) lie upon the point (56). Pitch motion and roll motion are separately and independently imparted to mirror (28) by a pair of pitch paddles (34) and a pair of roll paddles (36) that are independently and separately moved by control rods (76,80) driven by motors (78,82).

  13. EUV imaging experiment of an adaptive optics telescope

    NASA Astrophysics Data System (ADS)

    Kitamoto, S.; Shibata, T.; Takenaka, E.; Yoshida, M.; Murakami, H.; Shishido, Y.; Gotoh, N.; Nagasaki, K.; Takei, D.; Morii, M.

    2009-08-01

    We report an experimental result of our normal-incident EUV telescope tuned to a 13.5 nm band, with an adaptive optics. The optics consists of a spherical primary mirror and a secondary mirror. Both are coated by Mo/Si multilayer. The diameter of the primary and the secondary mirrors are 80 mm and 55mm, respectively. The secondary mirror is a deformable mirror with 31 bimorph-piezo electrodes. The EUV from a laser plasma source was exposed to a Ni mesh with 31 micro-m wires. The image of this mesh was obtained by a backilluminated CCD. The reference wave was made by an optical laser source with 1 μm pin-hole. We measure the wave form of this reference wave and control the secondary mirror to get a good EUV image. Since the paths of EUV and the optical light for the reference were different from each other, we modify the target wave from to control the deformable mirror, as the EUV image is best. The higher order Zernike components of the target wave form, as well as the tilts and focus components, were added to the reference wave form made by simply calculated. We confirmed the validity of this control and performed a 2.1 arc-sec resolution.

  14. Manufacturing and testing of a convex aspherical mirror for ASSIST

    NASA Astrophysics Data System (ADS)

    ter Horst, Rik; Stuik, Remko

    2012-09-01

    ASSIST is the testbed for the ESO Adaptive Optics Facility. The main objective of ASSIST is the characterization of the 1.2 meter deformable mirror which will replace the existing secondary of one of the 8 meter VLT telescopes. A large concave 1.65 meter diameter aspherical primary mirror combined with a 140 mm diameter convex aspherical secondary forms the main optical system of ASSIST. Two additional optical units provide the light sources and the wave front analyzing optics. Without having the possibility for checking the entire optical system as a whole, each individual mirror had to be manufactured and tested using reliable techniques. The secondary mirror for ASSIST (AM2) is made of an optically transparent material (BK7) with a specific and accurate backside radius in order to achieve a null test in transmission. Furthermore, not only the overall RMS surface error of AM2 is important, but due to the fact that it will be used in a setup that measures specific spatial frequencies, also the spatial frequencies of the surface error of AM2 is important. The aspherical surface is tested in double pass using an optical flat and an interferometer with a transmission sphere. Manufacturing of this asphere is mainly done by hand at the optical lab of NOVA-ASTRON. The final accuracy of the reflecting surface is within the required 50 nm RMS with a surface roughness of less than 2 nm RMS. This paper reports in more detail on manufacturing and testing of the a-spherical convex mirror.

  15. Mirror Technology

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Under a NASA contract, MI-CVD developed a process for producing bulk silicon carbide by means of a chemical vapor deposition process. The technology allows growth of a high purity material with superior mechanical/thermal properties and high polishability - ideal for mirror applications. The company employed the technology to develop three research mirrors for NASA Langley and is now marketing it as CVD SILICON CARBIDE. Its advantages include light weight, thermal stability and high reflectivity. The material has nuclear research facility applications and is of interest to industrial users of high power lasers.

  16. Conicoid Mirrors

    ERIC Educational Resources Information Center

    Castano, Diego J.; Hawkins, Lawrence C.

    2011-01-01

    The first-order equation relating object and image location for a mirror of arbitrary conic-sectional shape is derived. It is also shown that the parabolic reflecting surface is the only one free of aberration and only in the limiting case of distant sources. (Contains 3 figures.)

  17. Mirror Support

    NASA Technical Reports Server (NTRS)

    Baron, Richard L. (Inventor)

    2013-01-01

    Disclosed herein is a method of making a mirror support comprising a composite, the composite comprising a plurality of carbon nanotubes, wherein at least two of the plurality of carbon nanotubes are bonded to each other through a bridging moiety bound to each of the two carbon nanotubes, and a laminate comprising the composite.

  18. Performance of a magnetic driven tip-tilt mirror

    NASA Astrophysics Data System (ADS)

    Farinato, Jacopo; Esposito, Simone; Marchetti, Enrico; Ragazzoni, Roberto; Bruns, Donald G.

    1997-03-01

    ThermoTrex Corporation has designed and built a prototype of the fast steering mirror to be used for image motion control in the TNG adaptive optics system. The principal characteristic of this mirror is the use of voice coil actuators whose positions are controlled with closed loops based on capacitive sensors. Here we report the main features of the mirror assembly and laboratory measurements done to characterize the mirror behavior. The Bode diagram of the mirror is reported and discussed.

  19. MEMS Actuated Deformable Mirror

    SciTech Connect

    Papavasiliou, A; Olivier, S; Barbee, T; Walton, C; Cohn, M

    2005-11-10

    This ongoing work concerns the creation of a deformable mirror by the integration of MEMS actuators with Nanolaminate foils through metal compression boning. These mirrors will use the advantages of these disparate technologies to achieve dense actuation of a high-quality, continuous mirror surface. They will enable advanced adaptive optics systems in large terrestrial telescopes. While MEMS actuators provide very dense actuation with high precision they can not provide large forces typically necessary to deform conventional mirror surfaces. Nanolaminate foils can be fabricated with very high surface quality while their extraordinary mechanical properties enable very thin, flexible foils to survive the rigors of fabrication. Precise metal compression bonding allows the attachment of the fragile MEMS actuators to the thin nanolaminate foils without creating distortions at the bond sites. This paper will describe work in four major areas: (1) modeling and design, (2) bonding development, (3) nanolaminate foil development, (4) producing a prototype. A first-principles analytical model was created and used to determine the design parameters. A method of bonding was determined that is both strong, and minimizes the localized deformation or print through. Work has also been done to produce nanolaminate foils that are sufficiently thin, flexible and flat to be deformed by the MEMS actuators. Finally a prototype was produced by bonding thin, flexible nanolaminate foils to commercially available MEMS actuators.

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

    NASA Astrophysics Data System (ADS)

    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. Fabricating the LSST Mirrors: A Progress Report

    NASA Astrophysics Data System (ADS)

    Sebag, Jacques; Gressler, W.; Neill, D.; Hileman, E.; LSST Collaboration

    2009-01-01

    The LSST uses a modified Paul-Baker 3-mirror optical design with 8.4-m primary, 3.4-m secondary and 5-m tertiary mirrors feeding a 3 element refractive corrector to produce a 3.5-degree diameter field of view over a 64-cm flat focal surface in 6 spectral bands with excellent image quality. The proximity of the primary and tertiary surfaces enables fabrication of both mirrors from a single substrate. This unique design, referred to as the M1M3 monolith, offers significant advantages in the reduction of degrees of freedom during operational alignment and improved structural stiffness for the otherwise annular primary surface. The convex secondary will be the largest of its kind. As with all large optical elements, both of the LSST mirrors have long procurement times. In order to meet the LSST's first light schedule for the fall of 2014 we have started the fabrication process on both mirrors using private funding. The M1M3 monolith is being fabricated at the Steward Observatory Mirror Lab using their structured borosilicate spin casting technology. The M1M3 was successfully cast over the summer of 2008. The mold refractory cleanout process and detailed inspections are underway in preparation for back side processing. The casting includes special design features to enable the mirror to operate under the increased loads caused by the high accelerations needed by the LSST. The secondary mirror substrate is being made using Corning's Ultra Low Expansion (ULE) process, resulting in an annular meniscus mirror 100mm thick and a 1.8m diameter central hole. Glass selection for the secondary mirror has begun and the substrate will be fused late in 2008. Both mirrors are on schedule and their early start has substantially reduced risk within the LSST project. Topics: LSST Optics Mirrors

  2. Secondary School Music Education: A Case Study in Adapting to ICT Resource Limitations

    ERIC Educational Resources Information Center

    Crawford, Renee

    2009-01-01

    This article explores the current availability and use of information communication and technology (ICT) for music education purposes, and music technology resources and facilities, in Victorian government secondary schools. Survey data is presented providing a snapshot of the status of computer and technology resources in government secondary…

  3. Cancer prevention as biomodulation: targeting the initiating stimulus and secondary adaptations.

    PubMed

    Furth, Priscilla A

    2012-10-01

    In a medical sense, biomodulation could be considered a biochemical or cellular response to a disease or therapeutic stimulus. In cancer pathophysiology, the initial oncogenic stimulus leads to cellular and biochemical changes that allow cells, tissue, and organism to accommodate and accept the oncogenic insult. In epithelial cell cancer development, the process of carcinogenesis is frequently characterized by sequential cellular and biochemical adaptations as cells transition through hyperplasia, dysplasia, atypical dysplasia, carcinoma in situ, and invasive cancer. In some cases, the adaptations may persist after the initial oncogenic stimulus is gone in a type of "hit-and-run" oncogenesis. These pathophysiological changes may interfere with cancer prevention therapies targeted solely to the initial oncogenic insult, perhaps contributing to resistance development. Characterization of these accommodating adaptations could provide insight for the development of cancer preventive regimens that might more effectively biomodulate preneoplastic cells toward a more normal state. PMID:23050958

  4. Mirror, Mirror, on the Wall.

    ERIC Educational Resources Information Center

    Flowers, Jim; Rose, M. Annette

    1998-01-01

    Students use tables of anthropometric data, their own measurements, underlying principles of physics, and math to solve a problem. The problem is to determine the height of a wall mirror, and where to mount it, so that 90% of the clientele can view their entire length without stretching or bending. (Author)

  5. Farsi Version of Social Skills Rating System-Secondary Student Form: Cultural Adaptation, Reliability and Construct Validity

    PubMed Central

    Eslami, Ahmad Ali; Amidi Mazaheri, Maryam; Mostafavi, Firoozeh; Abbasi, Mohamad Hadi; Noroozi, Ensieh

    2014-01-01

    Objective: Assessment of social skills is a necessary requirement to develop and evaluate the effectiveness of cognitive and behavioral interventions. This paper reports the cultural adaptation and psychometric properties of the Farsi version of the social skills rating system-secondary students form (SSRS-SS) questionnaire (Gresham and Elliot, 1990), in a normative sample of secondary school students. Methods: A two-phase design was used that phase 1 consisted of the linguistic adaptation and in phase 2, using cross-sectional sample survey data, the construct validity and reliability of the Farsi version of the SSRS-SS were examined in a sample of 724 adolescents aged from 13 to 19 years. Results: Content validity index was excellent, and the floor/ceiling effects were low. After deleting five of the original SSRS-SS items, the findings gave support for the item convergent and divergent validity. Factor analysis revealed four subscales. Results showed good internal consistency (0.89) and temporal stability (0.91) for the total scale score. Conclusion: Findings demonstrated support for the use of the 27-item Farsi version in the school setting. Directions for future research regarding the applicability of the scale in other settings and populations of adolescents are discussed. PMID:25053964

  6. Difficulties Encountered by Soviet Immigrant Children in Adapting to Secondary Schools in Their New Homeland.

    ERIC Educational Resources Information Center

    Markus, Roberta L.

    1980-01-01

    Interviews with 207 Soviet immigrant adolescents reveal the adjustment difficulties they have in Canadian schools because of the different school system and changes in their socioeconomic status. The school and community must cooperate in facilitating the adaption of these students to the educational system. (PMJ)

  7. Mirror monochromator

    SciTech Connect

    Mankos, Marian; Shadman, Khashayar

    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

  8. Mirror systems

    SciTech Connect

    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)

  9. Integrated dual-stage deformable mirrors

    NASA Astrophysics Data System (ADS)

    Griffith, Mike; Laycock, Leslie; Archer, Nick; Myers, Richard; Kirby, Andrew; Doel, Peter; Brooks, David

    2010-07-01

    We present the results of a study on Dual-Stage Deformable Mirrors using Zonal Bimorph Deformable Mirror (ZBDM) technology. A high density 'tweeter' DM has been assembled onto a lower density, high dynamic range 'woofer' DM to generate an integrated mirror which offers both high resolution and dynamic range simultaneously. Such a device has the potential to significantly simplify the design of astronomical Adaptive Optics (AO) systems. The latest developments are presented, including the fabrication of a small scale demonstrator.

  10. Paper like cholesteric interferential mirror.

    PubMed

    Petriashvili, Gia; Japaridze, Kokhta; Devadze, Lali; Zurabishvili, Cisana; Sepashvili, Nino; Ponjavidze, Nino; De Santo, Maria P; Matranga, Mario A; Hamdi, Ridha; Ciuchi, Federica; Barberi, Riccardo

    2013-09-01

    A new type of flexible cholesteric liquid crystal mirror is presented. The simple and effective method for the deposition of a cholesteric mixture on a paper substrate and the particular design of the device give a homogeneous alignment of the cholesteric texture providing mirrors with an intense and uniform light reflectance. A desired polarization state for the reflected light, linear or circular, can be easily obtained varying the thickness and optical anisotropy of the polymer cover film. By using non-azobenzene based photosensitive materials a permanent array of RGB mirrors with high reflectivity can be obtained on the same device. Paper like reflective mirrors are versatile and they can find applications in reflective displays, adaptive optics, UV detectors and dosimeters, information recording, medicine and IR converters. PMID:24103954

  11. Three-point spherical mirror mount

    DOEpatents

    Cutburth, Ronald W.

    1990-01-01

    A three-point spherical mirror mount for use with lasers is disclosed. The improved mirror mount is adapted to provide a pivot ring having an outer surface with at least three spaced apart mating points to engage an inner spherical surface of a support housing.

  12. Three-point spherical mirror mount

    DOEpatents

    Cutburth, R.W.

    1984-01-23

    A three-point spherical mirror mount for use with lasers is disclosed. The improved mirror mount is adapted to provide a pivot ring having an outer surface with at least three spaced apart mating points to engage an inner spherical surface of a support housing.

  13. Analysis of the static deformation matching between numerical and experimental data on the voice-coil actuated deformable mirrors

    NASA Astrophysics Data System (ADS)

    Del Vecchio, Ciro; Briguglio, Runa; Riccardi, Armando; Xompero, Marco

    2014-08-01

    As any other modelling of a physical behavior, the numerical simulation of the mechanical response of an adaptive secondary mirror requires that the results match the experimental data. Such an agreement was recently demonstrated for the local mirror stiffness of the LBT and VLT Deformable Mirrors. A reliable modeling is a good tool for the extrapolation of the missing optical data (spider shadowing, edge vignetting, etc.) and a final goal method for simplifying, or even substituting, the complex optical measuring equipment required by the convex shells. In the present paper we compare the whole mirror deformation maps when a single actuator is poked, both in the optical data and in the numerical model. The limiting factors as well as a roadmap for future improvements will be identified.

  14. Status on NGST Mirror Technology

    NASA Technical Reports Server (NTRS)

    Jacobson, David

    2000-01-01

    The NGST primary mirror is anticipated to be a segmented deployable optic with segment size being in the range of 1 - 3 m depending on the details of the architecture. The secondary mirror will likely be a monolith similar in size to one of the primary mirror segments. Over the past 4 years the NGST program has initiated and implemented an aggressive lightweight cryogenic mirror technology program. The program was designed to challenge and excite the optical community in reaching a new standard in production of lightweight optics. The goal was to develop optics at less than 15 kg/sq m, operational at approx. 40 K and meeting the overall NGST observatory requirement for diffraction limited performance at 2 microns. In order to meet the NGST needs, technology efforts were initiated to investigate and develop mirrors in a variety of materials, which held promise for the program. The basic technology approaches have initially targeted the production of large mirrors in the 1.2 - 2.0 m diameter range (or side-to-side distance in the case of hexagonal optics). Although this size may not be the final size of an NGST primary mirror segment, it was felt that a 1.2 - 2.0 m optic would be of sufficient size to understand the mirror material and fabrication processes which drive the cost and schedule of mirror production. The ultimate goals of the technology program are both to demonstrate mirrors meeting, the NGST performance requirements, and to establish cost and schedule credibility for producing and implementing the mirrors for the NGST flight system. Establishing cost and schedule credibility is essential to NGST which is a cost capped mission, with past program experience demonstrating that the optics will be a large portion of the total cost of the program. The first two years of the program were dedicated to understanding; the various applicable materials, funding those materials to various levels of maturity and implementing the first large mirror procurement, the

  15. The Multiple Mirror Telescope

    NASA Astrophysics Data System (ADS)

    Beckers, J. M.; Ulich, B. L.; Shannon, R. R.; Carleton, N. P.; Geary, J. C.; Latham, D. W.; Angel, J. R. P.; Hoffmann, W. F.; Low, F. J.; Weymann, R. J.

    The Multiple Mirror Telescope (MMT), located on top of Mount Hopkins (2600 m) in Arizona, consists of six main telescope systems, each of which is a classical Cassegrain with a 1.8 m diameter parabolic primary with focal ratio f/2.7, and a hyperbolic secondary producing a final f/31.6 for each of the individual telescopes. The most significant departures of the MMT from conventional optical telescope technology are (1) the use of light-weight 'egg-crate' mirrors, which reduced the telescope weight, (2) the use of an alt-azimuth mount, which simplifies the gravitational effects on the structure, (3) the use of a ball-bearing support rather than hydrostatic bearings, resulting in cost savings and less maintenance, (4) the use of spur gear drives rather than worm gears, and (5) the use of multiple coaligned light collectors rather than a single monolithic mirror. Early multiple objective telescopes are discussed, and the early history of the MMT project is given. The design and performance of the telescope are explained, and MMT instrumentation (spectrograph, optical design, detector, infrared photometer, SAO CCD camera) is given. Astronomical research with the telescope is discussed, along with plans for future multiple objective telescopes.

  16. First closed-loop visible AO test results for the advanced adaptive secondary AO system for the Magellan Telescope: MagAO's performance and status

    NASA Astrophysics Data System (ADS)

    Close, Laird M.; Males, Jared R.; Kopon, Derek A.; Gasho, Victor; Follette, Katherine B.; Hinz, Phil; Morzinski, Katie; Uomoto, Alan; Hare, Tyson; Riccardi, Armando; Esposito, Simone; Puglisi, Alfio; Pinna, Enrico; Busoni, Lorenzo; Arcidiacono, Carmelo; Xompero, Marco; Briguglio, Runa; Quiros-Pacheco, Fernando; Argomedo, Javier

    2012-07-01

    The heart of the 6.5 Magellan AO system (MagAO) is a 585 actuator adaptive secondary mirror (ASM) with <1 msec response times (0.7 ms typically). This adaptive secondary will allow low emissivity and high-contrast AO science. We fabricated a high order (561 mode) pyramid wavefront sensor (similar to that now successfully used at the Large Binocular Telescope). The relatively high actuator count (and small projected ~23 cm pitch) allows moderate Strehls to be obtained by MagAO in the “visible” (0.63-1.05 μm). To take advantage of this we have fabricated an AO CCD science camera called "VisAO". Complete “end-to-end” closed-loop lab tests of MagAO achieve a solid, broad-band, 37% Strehl (122 nm rms) at 0.76 μm (i’) with the VisAO camera in 0.8” simulated seeing (13 cm ro at V) with fast 33 mph winds and a 40 m Lo locked on R=8 mag artificial star. These relatively high visible wavelength Strehls are enabled by our powerful combination of a next generation ASM and a Pyramid WFS with 400 controlled modes and 1000 Hz sample speeds (similar to that used successfully on-sky at the LBT). Currently only the VisAO science camera is used for lab testing of MagAO, but this high level of measured performance (122 nm rms) promises even higher Strehls with our IR science cameras. On bright (R=8 mag) stars we should achieve very high Strehls (>70% at H) in the IR with the existing MagAO Clio2 (λ=1-5.3 μm) science camera/coronagraph or even higher (~98% Strehl) the Mid-IR (8-26 microns) with the existing BLINC/MIRAC4 science camera in the future. To eliminate non-common path vibrations, dispersions, and optical errors the VisAO science camera is fed by a common path advanced triplet ADC and is piggy-backed on the Pyramid WFS optical board itself. Also a high-speed shutter can be used to block periods of poor correction. The entire system passed CDR in June 2009, and we finished the closed-loop system level testing phase in December 2011. Final system acceptance (

  17. Testing large telescope mirrors in the optical shop by an autocollimation method with multiple pendulum flat mirrors.

    PubMed

    Ningsheng, H

    1980-08-15

    Design and a compensation technique are presented to enable slope error measurements to be made via use of a pendulum having a small flat mirror mounted on the lower end. A multiplicity of such pendulum mirrors can act as a substitute for a full diameter flat for testing large astronomical primary and secondary mirrors. PMID:20234490

  18. Membrane Mirrors With Bimorph Shape Actuators

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok

    2003-01-01

    Deformable mirrors of a proposed type would be equipped with relatively-large-stroke microscopic piezoelectric actuators that would be used to maintain their reflective surfaces in precise shapes. These mirrors would be members of the class of MEMS-DM (for microelectromechanical system deformable mirror) devices, which offer potential for a precise optical control in adaptive-optics applications in such diverse fields as astronomy and vision science. The proposed mirror would be fabricated, in part, by use of a membrane-transfer technique. The actuator design would contain bimorph-type piezoelectric actuators.

  19. Baiji genomes reveal low genetic variability and new insights into secondary aquatic adaptations

    PubMed Central

    Zhou, Xuming; Sun, Fengming; Xu, Shixia; Fan, Guangyi; Zhu, Kangli; Liu, Xin; Chen, Yuan; Shi, Chengcheng; Yang, Yunxia; Huang, Zhiyong; Chen, Jing; Hou, Haolong; Guo, Xuejiang; Chen, Wenbin; Chen, Yuefeng; Wang, Xiaohong; Lv, Tian; Yang, Dan; Zhou, Jiajian; Huang, Bangqing; Wang, Zhengfei; Zhao, Wei; Tian, Ran; Xiong, Zhiqiang; Xu, Junxiao; Liang, Xinming; Chen, Bingyao; Liu, Weiqing; Wang, Junyi; Pan, Shengkai; Fang, Xiaodong; Li, Ming; Wei, Fuwen; Xu, Xun; Zhou, Kaiya; Wang, Jun; Yang, Guang

    2013-01-01

    The baiji, or Yangtze River dolphin (Lipotes vexillifer), is a flagship species for the conservation of aquatic animals and ecosystems in the Yangtze River of China; however, this species has now been recognized as functionally extinct. Here we report a high-quality draft genome and three re-sequenced genomes of L. vexillifer using Illumina short-read sequencing technology. Comparative genomic analyses reveal that cetaceans have a slow molecular clock and molecular adaptations to their aquatic lifestyle. We also find a significantly lower number of heterozygous single nucleotide polymorphisms in the baiji compared to all other mammalian genomes reported thus far. A reconstruction of the demographic history of the baiji indicates that a bottleneck occurred near the end of the last deglaciation, a time coinciding with a rapid decrease in temperature and the rise of eustatic sea level. PMID:24169659

  20. Baiji genomes reveal low genetic variability and new insights into secondary aquatic adaptations.

    PubMed

    Zhou, Xuming; Sun, Fengming; Xu, Shixia; Fan, Guangyi; Zhu, Kangli; Liu, Xin; Chen, Yuan; Shi, Chengcheng; Yang, Yunxia; Huang, Zhiyong; Chen, Jing; Hou, Haolong; Guo, Xuejiang; Chen, Wenbin; Chen, Yuefeng; Wang, Xiaohong; Lv, Tian; Yang, Dan; Zhou, Jiajian; Huang, Bangqing; Wang, Zhengfei; Zhao, Wei; Tian, Ran; Xiong, Zhiqiang; Xu, Junxiao; Liang, Xinming; Chen, Bingyao; Liu, Weiqing; Wang, Junyi; Pan, Shengkai; Fang, Xiaodong; Li, Ming; Wei, Fuwen; Xu, Xun; Zhou, Kaiya; Wang, Jun; Yang, Guang

    2013-01-01

    The baiji, or Yangtze River dolphin (Lipotes vexillifer), is a flagship species for the conservation of aquatic animals and ecosystems in the Yangtze River of China; however, this species has now been recognized as functionally extinct. Here we report a high-quality draft genome and three re-sequenced genomes of L. vexillifer using Illumina short-read sequencing technology. Comparative genomic analyses reveal that cetaceans have a slow molecular clock and molecular adaptations to their aquatic lifestyle. We also find a significantly lower number of heterozygous single nucleotide polymorphisms in the baiji compared to all other mammalian genomes reported thus far. A reconstruction of the demographic history of the baiji indicates that a bottleneck occurred near the end of the last deglaciation, a time coinciding with a rapid decrease in temperature and the rise of eustatic sea level. PMID:24169659

  1. Chinese "Magic" Mirrors.

    ERIC Educational Resources Information Center

    Swinson, Derek B.

    1992-01-01

    Chinese "magic" mirrors are made from bronze with the front side a mirror and the reverse side a molded image. When light is reflected from the mirror,the image on the reverse side appears. Discusses reflections of conventional mirrors, possible explanations for the magic mirror phenomenon, and applications of the phenomenon to semiconductor…

  2. Adaptation.

    PubMed

    Broom, Donald M

    2006-01-01

    The term adaptation is used in biology in three different ways. It may refer to changes which occur at the cell and organ level, or at the individual level, or at the level of gene action and evolutionary processes. Adaptation by cells, especially nerve cells helps in: communication within the body, the distinguishing of stimuli, the avoidance of overload and the conservation of energy. The time course and complexity of these mechanisms varies. Adaptive characters of organisms, including adaptive behaviours, increase fitness so this adaptation is evolutionary. The major part of this paper concerns adaptation by individuals and its relationships to welfare. In complex animals, feed forward control is widely used. Individuals predict problems and adapt by acting before the environmental effect is substantial. Much of adaptation involves brain control and animals have a set of needs, located in the brain and acting largely via motivational mechanisms, to regulate life. Needs may be for resources but are also for actions and stimuli which are part of the mechanism which has evolved to obtain the resources. Hence pigs do not just need food but need to be able to carry out actions like rooting in earth or manipulating materials which are part of foraging behaviour. The welfare of an individual is its state as regards its attempts to cope with its environment. This state includes various adaptive mechanisms including feelings and those which cope with disease. The part of welfare which is concerned with coping with pathology is health. Disease, which implies some significant effect of pathology, always results in poor welfare. Welfare varies over a range from very good, when adaptation is effective and there are feelings of pleasure or contentment, to very poor. A key point concerning the concept of individual adaptation in relation to welfare is that welfare may be good or poor while adaptation is occurring. Some adaptation is very easy and energetically cheap and

  3. Large Scale Nanolaminate Deformable Mirror

    SciTech Connect

    Papavasiliou, A; Olivier, S; Barbee, T; Miles, R; Chang, K

    2005-11-30

    This work concerns the development of a technology that uses Nanolaminate foils to form light-weight, deformable mirrors that are scalable over a wide range of mirror sizes. While MEMS-based deformable mirrors and spatial light modulators have considerably reduced the cost and increased the capabilities of adaptive optic systems, there has not been a way to utilize the advantages of lithography and batch-fabrication to produce large-scale deformable mirrors. This technology is made scalable by using fabrication techniques and lithography that are not limited to the sizes of conventional MEMS devices. Like many MEMS devices, these mirrors use parallel plate electrostatic actuators. This technology replicates that functionality by suspending a horizontal piece of nanolaminate foil over an electrode by electroplated nickel posts. This actuator is attached, with another post, to another nanolaminate foil that acts as the mirror surface. Most MEMS devices are produced with integrated circuit lithography techniques that are capable of very small line widths, but are not scalable to large sizes. This technology is very tolerant of lithography errors and can use coarser, printed circuit board lithography techniques that can be scaled to very large sizes. These mirrors use small, lithographically defined actuators and thin nanolaminate foils allowing them to produce deformations over a large area while minimizing weight. This paper will describe a staged program to develop this technology. First-principles models were developed to determine design parameters. Three stages of fabrication will be described starting with a 3 x 3 device using conventional metal foils and epoxy to a 10-across all-metal device with nanolaminate mirror surfaces.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Dynamic Reconstruction and Multivariable Control for Force-Actuated, Thin Facesheet Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Grocott, Simon C. O.; Miller, David W.

    1997-01-01

    The Multiple Mirror Telescope (MMT) under development at the University of Arizona takes a new approach in adaptive optics placing a large (0.65 m) force-actuated, thin facesheet deformable mirror at the secondary of an astronomical telescope, thus reducing the effects of emissivity which are important in IR astronomy. However, The large size of the mirror and low stiffness actuators used drive the natural frequencies of the mirror down into the bandwidth of the atmospheric distortion. Conventional adaptive optics takes a quasi-static approach to controlling the, deformable mirror. However, flexibility within the control bandwidth calls for a new approach to adaptive optics. Dynamic influence functions are used to characterize the influence of each actuator on the surface of the deformable mirror. A linearized model of atmospheric distortion is combined with dynamic influence functions to produce a dynamic reconstructor. This dynamic reconstructor is recognized as an optimal control problem. Solving the optimal control problem for a system with hundreds of actuators and sensors is formidable. Exploiting the circularly symmetric geometry of the mirror, and a suitable model of atmospheric distortion, the control problem is divided into a number of smaller decoupled control problems using circulant matrix theory. A hierarchic control scheme which seeks to emulate the quasi-static control approach that is generally used in adaptive optics is compared to the proposed dynamic reconstruction technique. Although dynamic reconstruction requires somewhat more computational power to implement, it achieves better performance with less power usage, and is less sensitive than the hierarchic technique.

  6. Double arch mirror study

    NASA Technical Reports Server (NTRS)

    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.

  7. MindMatters--A Programme for the Promotion of Mental Health in Primary and Secondary Schools: Results of an Evaluation of the German Language Adaptation

    ERIC Educational Resources Information Center

    Franze, M.; Paulus, P.

    2009-01-01

    Purpose: The purpose of this article is to present a German adaptation of the Australian programme MindMatters for school mental health promotion in secondary schools. Design/methodology/approach: As well as other methods, the external evaluation consisted of a questionnaire-based pre-post-design (at one year interval of measurement; n=633…

  8. Teaching Students with Special Needs in Secondary and Vocational Programs: Classroom, Building, Equipment and Instructional Modifications and Adaptations. Working Paper Series.

    ERIC Educational Resources Information Center

    Fletcher, Janice; Parks, A. Lee

    This manuscript, provided in a format that lends itself to workshop presentation, contains materials for vocational and secondary educators on curriculum and classroom modifications for handicapped learners. Content is divided into seven areas. The first section discusses overall curricular modification and adaptation for handicapped students. In…

  9. Adapt

    NASA Astrophysics Data System (ADS)

    Bargatze, L. F.

    2015-12-01

    Active Data Archive Product Tracking (ADAPT) is a collection of software routines that permits one to generate XML metadata files to describe and register data products in support of the NASA Heliophysics Virtual Observatory VxO effort. ADAPT is also a philosophy. The ADAPT concept is to use any and all available metadata associated with scientific data to produce XML metadata descriptions in a consistent, uniform, and organized fashion to provide blanket access to the full complement of data stored on a targeted data server. In this poster, we present an application of ADAPT to describe all of the data products that are stored by using the Common Data File (CDF) format served out by the CDAWEB and SPDF data servers hosted at the NASA Goddard Space Flight Center. These data servers are the primary repositories for NASA Heliophysics data. For this purpose, the ADAPT routines have been used to generate data resource descriptions by using an XML schema named Space Physics Archive, Search, and Extract (SPASE). SPASE is the designated standard for documenting Heliophysics data products, as adopted by the Heliophysics Data and Model Consortium. The set of SPASE XML resource descriptions produced by ADAPT includes high-level descriptions of numerical data products, display data products, or catalogs and also includes low-level "Granule" descriptions. A SPASE Granule is effectively a universal access metadata resource; a Granule associates an individual data file (e.g. a CDF file) with a "parent" high-level data resource description, assigns a resource identifier to the file, and lists the corresponding assess URL(s). The CDAWEB and SPDF file systems were queried to provide the input required by the ADAPT software to create an initial set of SPASE metadata resource descriptions. Then, the CDAWEB and SPDF data repositories were queried subsequently on a nightly basis and the CDF file lists were checked for any changes such as the occurrence of new, modified, or deleted

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  11. Floating mirror mount

    SciTech Connect

    Koop, D.E.

    1989-01-03

    This patent describes a floating mirror mount for a mirror of a laser is described consisting of: a mirror having a front surface and a back surface, a keeper encircling the mirror and having a peripheral flange engaging the front surface of the mirror when the mirror is not installed in a laser, a retainer positioned rearwardly of the back surface of the mirror and connected to the keeper and having a spring seating surface, spring means engageable with the spring seating surface of the retainer for exerting a resilient biasing force on the mirror, and fastening means for connecting the retainer to the mirror positioning structure of the laser on installation of the mirror mount in the laser.

  12. Deformable mirror design of Subaru LGSAO system

    NASA Astrophysics Data System (ADS)

    Oya, Shin; Guyon, Olivier; Watanabe, Makoto; Hayano, Yutaka; Takami, Hideki; Iye, Masanori; Arimoto, Nobuo; Colley, Stephen; Eldred, Michael; Kane, Thomas; Hattori, Masayuki; Saito, Yoshihiko; Kamata, Yukiko; Kobayashi, Naoto; Minowa, Yosuke; Goto, Miwa; Takato, Naruhisa

    2004-10-01

    As an upgrade plan of Subaru adaptive optics facility, laser-guide-star adaptive-optics (LGSAO) project is on going. One of key components of the project is a deformable mirror (DM). The DM for LGSAO is a bimorph type of PZT with 188 control elements. The specification of design is presented together with the analysis of stroke and vibration properties by FEM.

  13. Ultrasonic Time Reversal Mirrors

    NASA Astrophysics Data System (ADS)

    Fink, Mathias; Montaldo, Gabriel; Tanter, Mickael

    2004-11-01

    For more than ten years, time reversal techniques have been developed in many different fields of applications including detection of defects in solids, underwater acoustics, room acoustics and also ultrasound medical imaging and therapy. The essential property that makes time reversed acoustics possible is that the underlying physical process of wave propagation would be unchanged if time were reversed. In a non dissipative medium, the equations governing the waves guarantee that for every burst of sound that diverges from a source there exists in theory a set of waves that would precisely retrace the path of the sound back to the source. If the source is pointlike, this allows focusing back on the source whatever the medium complexity. For this reason, time reversal represents a very powerful adaptive focusing technique for complex media. The generation of this reconverging wave can be achieved by using Time Reversal Mirrors (TRM). It is made of arrays of ultrasonic reversible piezoelectric transducers that can record the wavefield coming from the sources and send back its time-reversed version in the medium. It relies on the use of fully programmable multi-channel electronics. In this paper we present some applications of iterative time reversal mirrors to target detection in medical applications.

  14. The Adaptive Optics System for the New 6.5 Meter MMT Optical/Infrared Telescope

    NASA Astrophysics Data System (ADS)

    McGuire, Patrick C.; Lloyd-Hart, Michael; Angel, J. Roger P.; Angeli, George Z.; Johnson, Robert L.; Fitz-Patrick, Bruce C.; Davison, Warren B.; Sarlot, Roland J.; Bresloff, Cyndy J.; Hughes, John M.; Miller, Steve M.; Schaller, Phillip; Wildi, Francois P.; Kenworthy, Matthew A.; Cordova, Richard M.; Rademacher, Matthew L.; Rascon, Mario H.; Langlois, Maud; Roberts, Thomas; McCarthy, Don; Burge, James H.; Rhoadarmer, Troy A.; Shelton, J. Christopher; Jacobsen, Bruce; Salinari, Piero; Brusa, Guido; Del Vecchio, Ciro; Biasi, Roberto; Gallieni, Daniele; Sandler, David G.; Barrett, Todd K.

    1999-10-01

    The Multiple Mirror Telescope (MMT) is currently being upgraded to a single 6.5 meter diameter mirror and should see first light at prime focus in September 1999. We are constructing an F/15 adaptive optics (AO) system which will be an integral part of the new MMT with first light in early 2000, removing the effect of atmospheric turbulence so that images near the diffraction limit in the near-infrared can be achieved. The deformable element of this system is a 64 cm diameter secondary mirror composed of a 1.8 mm thick thin glass shell and 336 voice coil actuators operating at 1 kHz. This is the first system that uses the secondary mirror as the correcting element, which means thermal background is minimized. We will primarily present an overview of the adaptive optics technique, followed by select results which will include the laboratory testing of the AO system components with a solid secondary, data taken with the wavefront sensor camera at prime focus of the new MMT, and tests of the secondary mirror control system.

  15. A ferrofluidic deformable mirror for ophthalmology

    NASA Astrophysics Data System (ADS)

    Macpherson, J. B.; Thibault, S.; Borra, E. F.; Ritcey, A. M.; Carufel, N.; Asselin, D.; Jerominek, H.; Campbell, M. C. W.

    2005-09-01

    Optical aberrations reduce the imaging quality of the human eye. In addition to degrading vision, this limits our ability to illuminate small points of the retina for therapeutic, surgical or diagnostic purposes. When viewing the rear of the eye, aberrations cause structures in the fundus to appear blurred, limiting the resolution of ophthalmoscopes (diagnostic instruments used to image the eye). Adaptive optics, such as deformable mirrors may be used to compensate for aberrations, allowing the eye to work as a diffraction-limited optical element. Unfortunately, this type of correction has not been widely available for ophthalmic applications because of the expense and technical limitations of current deformable mirrors. We present preliminary design and characterisation of a deformable mirror suitable for ophthalmology. In this ferrofluidic mirror, wavefronts are reflected from a fluid whose surface shape is controlled by a magnetic field. Challenges in design are outlined, as are advantages over traditional deformable mirrors.

  16. Afocal correctors for paraboloidal mirrors.

    PubMed

    Wynne, C G

    1967-07-01

    A new form of field corrector for astronomical telescopes with paraboloidal primary mirrors is described. It consists of four separated spherical surfaced lenses and gives improved aberration correction. The method of designing is described, and the adaptability of the design to telescopes of different characteristics is discussed. Numerical data and details of performance are given for a specific design for the Palomar Observatory 200-in. (5.08-m) telescope. PMID:20062169

  17. The Magellan Adaptive Secondary VisAO Camera: diffraction-limited broadband visible imaging and 20mas fiber array IFU

    NASA Astrophysics Data System (ADS)

    Kopon, Derek; Close, Laird M.; Males, Jared; Gasho, Victor; Follette, Katherine

    2010-07-01

    The Magellan Adaptive Secondary AO system, scheduled for first light in the fall of 2011, will be able to simultaneously perform diffraction limited AO science in both the mid-IR, using the BLINC/MIRAC4 10μm camera, and in the visible using our novel VisAO camera. The VisAO camera will be able to operate as either an imager, using a CCD47 with 8.5 mas pixels, or as an IFS, using a custom fiber array at the focal plane with 20 mas elements in its highest resolution mode. In imaging mode, the VisAO camera will have a full suite of filters, coronagraphic focal plane occulting spots, and SDI prism/filters. The imaging mode should provide ~20% mean Strehl diffraction-limited images over the band 0.5-1.0 μm. In IFS mode, the VisAO instrument will provide R~1,800 spectra over the band 0.6-1.05 μm. Our unprecedented 20 mas spatially resolved visible spectra would be the highest spatial resolution achieved to date, either from the ground or in space. We also present lab results from our recently fabricated advanced triplet Atmospheric Dispersion Corrector (ADC) and the design of our novel wide-field acquisition and active optics lens. The advanced ADC is designed to perform 58% better than conventional doublet ADCs and is one of the enabling technologies that will allow us to achieve broadband (0.5-1.0μm) diffraction limited imaging and wavefront sensing in the visible.

  18. Novel technologies for small deformable mirrors

    NASA Astrophysics Data System (ADS)

    Strachan, Mel; Myers, Richard; Cooke, Kevin; Hampshire, Joanne; Hough, Jim; Rowan, Sheila; van Veggel, Marielle; Kirk, Katherine; Hutson, David; Uzgur, Erman; Kim, Shin-Sung

    2010-07-01

    Adaptive optic requirements for instrumentation such as EAGLE for the European extremely large telescope present an enormous challenge to deformable mirror technology. We have developed a unique approach using fabricated arrays of multilayer actuator technology to address the requirements of actuator density and deflection. Our programme of work has uncovered a novel approach which has led to a built in test capability. We will present the outcomes of our work which we believe will lead to a compact deformable mirror.

  19. Deformable Mirrors Correct Optical Distortions

    NASA Technical Reports Server (NTRS)

    2010-01-01

    By combining the high sensitivity of space telescopes with revolutionary imaging technologies consisting primarily of adaptive optics, the Terrestrial Planet Finder is slated to have imaging power 100 times greater than the Hubble Space Telescope. To this end, Boston Micromachines Corporation, of Cambridge, Massachusetts, received Small Business Innovation Research (SBIR) contracts from the Jet Propulsion Laboratory for space-based adaptive optical technology. The work resulted in a microelectromechanical systems (MEMS) deformable mirror (DM) called the Kilo-DM. The company now offers a full line of MEMS DMs, which are being used in observatories across the world, in laser communication, and microscopy.

  20. Evaluation of microfabricated deformable mirror systems

    NASA Astrophysics Data System (ADS)

    Cowan, William D.; Lee, Max K.; Bright, Victor M.; Welsh, Byron M.

    1998-09-01

    This paper presents recent result for aberration correction and beam steering experiments using polysilicon surface micromachined piston micromirror arrays. Microfabricated deformable mirrors offer a substantial cost reduction for adaptive optic systems. In addition to the reduced mirror cost, microfabricated mirrors typically require low control voltages, thus eliminating high voltage amplifiers. The greatly reduced cost per channel of adaptive optic systems employing microfabricated deformable mirrors promise high order aberration correction at low cost. Arrays of piston micromirrors with 128 active elements were tested. Mirror elements are on a 203 micrometers 12 by 12 square grid. The overall array size is 2.4 mm square. The arrays were fabricated in the commercially available DARPA supported MUMPs surface micromachining foundry process. The cost per mirror array in this prototyping process is less than 200 dollars. Experimental results are presented for a hybrid correcting element comprised of a lenslet array and piston micromirror array, and for a piston micromirror array only. Also presented is a novel digital deflection micromirror which requires no digital to analog converters, further reducing the cost of adaptive optics system.

  1. 20/20: Making a Better Giant Segmented Mirror Telescope by Interferometry

    NASA Astrophysics Data System (ADS)

    Angel, J. R. P.

    2001-11-01

    How should a Giant Segmented Mirror Telescope be built? For given primary mirror area, higher performance (sharper images and better sensitivity to extra-solar planets) can be realized in a configuration with two independent elements rather than a single dish. In our 20/20 telescope concept, two 21 m diameter telescopes (equivalent to a 30 m single dish) can be operated independently or moved around a 100 m track for operation as an interferometer. The individual foci at f/11 have 12 arcminute, seeing-limited fields. Correction to the diffraction limit (0.01 arcsec at 1 micron wavelength) will be made with adaptive secondary mirrors. For interferometry, the telescopes will be driven in tandem to keep the desired baseline, perpendicular to the source. The beams will be combined at a cryostat positioned midway between. In Fizeau mode, a much larger field of view is achieved than for conventional, fixed-element, Michelson interferometers, 30 arcsec at 2.2 microns, and the resolution of 2-7 mas, (depending on baselines used) is higher than the 15 mas for a 30 m dish. The 20/20 telescope will have the sensitivity to detect Earthlike planets of the nearest stars, through its very efficient implementation of Bracewell nulling interferometry. To minimize performance degradation from segmentation, each 21 m primary will be made from just 7 rigid segments, each like a primary mirror of the Large Binocular Telescope. The adaptive secondary mirrors will be similarly segmented, for detailed correction of wind-induced phase steps at the primary segment boundaries. Very low thermal background is projected because the adaptive correction is made at the secondary mirrors and interferometric beam combination takes place in a cryostat after just one additional Nasmyth flat reflection. Hydrostatic bearings will be used for smooth translation around the 100 m track. Each telescope with f/0.7 primary weighs 850 tons, with lowest resonant frequency > 5.5 Hz, comparable to current 8 m

  2. Kinematic high bandwidth mirror mount

    DOEpatents

    Kuklo, T.C.

    1995-03-21

    An adjustable mirror mount system for a mirror is disclosed comprising a mirror support having a planar surface thereon, a mirror frame containing a mirror and having a planar surface behind the mirror facing the planar surface of the mirror support and parallel to the reflecting surface of the mirror and mounted pivotally to the mirror support at a point central to the frame, a first adjustment means between the mirror support and the mirror frame spaced from the central pivot mount for adjusting the movement of the mirror along one axis lying in the plane of the planar surface of the mirror frame; and a second adjustment means between the mirror support and the mirror frame spaced from the central pivot mount for adjusting the movement of the mirror along a second axis lying in the plane of the planar surface of the mirror frame and perpendicular to the first axis. 7 figures.

  3. Kinematic high bandwidth mirror mount

    DOEpatents

    Kuklo, Thomas C.

    1995-01-01

    An adjustable mirror mount system for a mirror is disclosed comprising a mirror support having a planar surface thereon, a mirror frame containing a mirror and having a planar surface behind the mirror facing the planar surface of the mirror support and parallel to the reflecting surface of the mirror and mounted pivotally to the mirror support at a point central to the frame, a first adjustment means between the mirror support and the mirror frame spaced from the central pivot mount for adjusting the movement of the mirror along one axis lying in the plane of the planar surface of the mirror frame; and a second adjustment means between the mirror support and the mirror frame spaced from the central pivot mount for adjusting the movement of the mirror along a second axis lying in the plane of the planar surface of the mirror frame and perpendicular to the first axis.

  4. Deploying the testbed for the VLT adaptive optics facility: ASSIST

    NASA Astrophysics Data System (ADS)

    Stuik, Remko; La Penna, Paolo; Dupuy, Christophe; de Haan, Menno; Arsenault, Robin; Boland, Wilfried; Elswijk, Eddy; ter Horst, Rik; Hubin, Norbert; Madec, Pierre-Yves; Molster, Frank; Wiegers, Emiel

    2012-07-01

    The ESO Very Large Telescope Adaptive Optics Facility (VLT-AOF) will transform the VLT Unit Telescope 4 to an Adaptive Telescope. In absence of an intermediate focus before the Adaptive Secondary in this Ritchey-Chrétien type telescope and in order to reduce the testing and calibration of the system on-sky, ASSIST, The Adaptive Secondary Setup and Instrument STimulator, was developed. It provides an off-sky testing facility for the ESO AOF and will provide a full testing environment for three elements of the VLT Adaptive Optics Facility: the Deformable Secondary Mirror (DSM) and the AO modules for MUSE and HAWK-I (GALACSI and GRAAL). ASSIST was delivered to ESO Garching, where it was assembled and tested. Currently ASSIST is being integrated with the Deformable Secondary Mirror, the first step in the full system testing of the two AO systems for the VLT AOF on ASSIST. This paper briefly reviews the design and properties of ASSIST and reports on the first results of ASSIST in stand-alone mode.

  5. Is ESO's adaptive optics facility suited for MCAO?

    NASA Astrophysics Data System (ADS)

    Marchetti, Enrico; Amico, Paola; Fedrigo, Enrico; Glindemann, Andreas; Hubin, Norbert; La Penna, Paolo; Le Louarn, Miska; Madec, Pierre-Yves

    2010-07-01

    As of 2013, the ESO's VLT will be equipped with the Adaptive Optics Facility for Ground Layer and Laser Tomography adaptive optics assisted imaging and spectroscopy, using a Deformable Secondary Mirror and four Laser Guide Stars. Following the successful experience of the MAD demonstrator, we initiated a speculative study to evaluate the performance gain obtained by implementing a type of Multi-Conjugate Adaptive Optics correction that benefits from the unique features provided by the AOF. In this paper we present the basic concept and provide a first estimation of the correction performance obtained in the near infrared.

  6. Piezoelectric deformable mirror technologies for astronomy at IOE, CAS

    NASA Astrophysics Data System (ADS)

    Guan, Chunlin; Fan, Xinlong; Zhang, Xiaojun; Zhou, Hong; Mu, Jinbo; Xue, Lixia; Wei, Kai; Xian, Hao; Rao, Changhui; Zhang, Yudong; Ling, Ning

    2014-07-01

    Institute of Optics & Electronics (IOE), Chinese Academy of Sciences (CAS) has more than 30 years' experience on piezoelectric deformable mirror (DM) technologies research and developing since early 1980s. Several DMs of IOE have been used in many different application systems. A brief history of piezoelectric DMs development in IOE and several recently achievements, and the main characters, performance and test results of the DMs for astronomy will be presented in this paper. 1) High-order DM. DM prototype with 913-element for 4m telescope has been fabricated and tested in laboratory. 2) Adaptive Secondary Mirror (ASM). A 73-element ASM prototype with 12 microns stroke for 1.8m telescope has been fabricated. It will be installed onto the 1.8m telescope with a compact adaptive optics (AO) system. 3) Small spacing DM. A 6mm spacing 127-element DM based on the same construction with the High-order DM has been used in AO system of 1m New Vacuum Solar Telescope (NVST) in Yunnan Observatories. Higher density (3mm spacing) DM based on a novel construction has being developed. In 2012, the novel DM prototype with 100-element was fabricated and tested carefully in laboratory. Beside, a 6mm spacing 151-element DM based on the novel construction has being fabricated for the solar AO system.

  7. Topological Mirror Superconductivity

    NASA Astrophysics Data System (ADS)

    Zhang, Fan; Kane, C. L.; Mele, E. J.

    2013-08-01

    We demonstrate the existence of topological superconductors (SCs) protected by mirror and time-reversal symmetries. D-dimensional (D=1, 2, 3) crystalline SCs are characterized by 2D-1 independent integer topological invariants, which take the form of mirror Berry phases. These invariants determine the distribution of Majorana modes on a mirror symmetric boundary. The parity of total mirror Berry phase is the Z2 index of a class DIII SC, implying that a DIII topological SC with a mirror line must also be a topological mirror SC but not vice versa and that a DIII SC with a mirror plane is always time-reversal trivial but can be mirror topological. We introduce representative models and suggest experimental signatures in feasible systems. Advances in quantum computing, the case for nodal SCs, the case for class D, and topological SCs protected by rotational symmetries are pointed out.

  8. Light, Color, and Mirrors.

    ERIC Educational Resources Information Center

    Tiburzi, Brian; Tamborino, Laurie; Parker, Gordon A.

    2000-01-01

    Describes an exercise in which students can use flashlights, mirrors, and colored paper to discover scientific principles regarding optics. Addresses the concepts of angles of incidence and reflection, colored vs. white light, and mirror images. (WRM)

  9. Attractive characteristics of mirrors

    NASA Astrophysics Data System (ADS)

    Post, R. F.; Ryutov, D. D.

    1994-12-01

    A summary of the attractive characteristics of mirror devices is presented. Recent progress in development of axisymmetric mirror devices is described. Potentialities of mirrors as a basis for D(3)He fusion power generators and high-flux neutron sources for fusion material tests are discussed.

  10. Indium Second-Surface Mirrors

    NASA Technical Reports Server (NTRS)

    Bouquet, F. L.; Hasegawa, T.

    1982-01-01

    Second-surface mirrors are formed by vapor deposition of indium onto glass. Mirrors have reflectances comparable to those of ordinary silver or aluminized mirrors and are expected to show superior corrosion resistance. Mirrors may be used in solar concentrators.

  11. Two well-corrected four-mirror telescopes

    NASA Technical Reports Server (NTRS)

    Korsch, D.

    1974-01-01

    A study has been conducted of a configuration resembling that of a Cassegrain telescope with two nested mirrors in the plane of the primary and two nested mirrors in the plane of the secondary. The focal plane was located in the plane of the first and the third mirror. The four surfaces available in the device for corrections made it possible to correct for third-order spherical aberration, coma, astigmatism, and distortion.

  12. Opinions on Further Strengthening and Improving Primary and Secondary School Moral Education Work to Adapt to the New Situation

    ERIC Educational Resources Information Center

    Chinese Education and Society, 2006

    2006-01-01

    In order to earnestly carry out the spirit of Comrade Jiang Zemin's February 1, 2000, "Conversations on Issues in Education" and his important speech at the Party Central Committee's Ideological and Political Work Conference; further strengthen and improve primary and secondary school (including vocational secondary school) moral education work;…

  13. Lightweight deformable mirrors for future space telescopes

    NASA Astrophysics Data System (ADS)

    Patterson, Keith

    This thesis presents a concept for ultra-lightweight deformable mirrors based on a thin substrate of optical surface quality coated with continuous active piezopolymer layers that provide modes of actuation and shape correction. This concept eliminates any kind of stiff backing structure for the mirror surface and exploits micro-fabrication technologies to provide a tight integration of the active materials into the mirror structure, to avoid actuator print-through effects. Proof-of-concept, 10-cm-diameter mirrors with a low areal density of about 0.5 kg/m2 have been designed, built and tested to measure their shape-correction performance and verify the models used for design. The low cost manufacturing scheme uses replication techniques, and strives for minimizing residual stresses that deviate the optical figure from the master mandrel. It does not require precision tolerancing, is lightweight, and is therefore potentially scalable to larger diameters for use in large, modular space telescopes. Other potential applications for such a laminate could include ground-based mirrors for solar energy collection, adaptive optics for atmospheric turbulence, laser communications, and other shape control applications. The immediate application for these mirrors is for the Autonomous Assembly and Reconfiguration of a Space Telescope (AAReST) mission, which is a university mission under development by Caltech, the University of Surrey, and JPL. The design concept, fabrication methodology, material behaviors and measurements, mirror modeling, mounting and control electronics design, shape control experiments, predictive performance analysis, and remaining challenges are presented herein. The experiments have validated numerical models of the mirror, and the mirror models have been used within a model of the telescope in order to predict the optical performance. A demonstration of this mirror concept, along with other new telescope technologies, is planned to take place during

  14. Towards plasma cleaning of ITER first mirrors

    NASA Astrophysics Data System (ADS)

    Moser, L.; Marot, L.; Eren, B.; Steiner, R.; Mathys, D.; Leipold, F.; Reichle, R.; Meyer, E.

    2015-06-01

    To avoid reflectivity losses in ITER's optical diagnostic systems, on-site cleaning of metallic first mirrors via plasma sputtering is foreseen to remove deposit build-ups migrating from the main wall. In this work, the influence of aluminium and tungsten deposits on the reflectivity of molybdenum mirrors as well as the possibility to clean them with plasma exposure is investigated. Porous ITER-like deposits are grown to mimic the edge conditions expected in ITER, and a severe degradation in the specular reflectivity is observed as these deposits build up on the mirror surface. In addition, dense oxide films are produced for comparisons with porous films. The composition, morphology and crystal structure of several films were characterized by means of scanning electron microscopy, x-ray photoelectron spectroscopy, x-ray diffraction and secondary ion mass spectrometry. The cleaning of the deposits and the restoration of the mirrors' optical properties are possible either with a Kaufman source or radio frequency directly applied to the mirror (or radio frequency plasma generated directly around the mirror surface). Accelerating ions of an external plasma source through a direct current applied onto the mirror does not remove deposits composed of oxides. A possible implementation of plasma cleaning in ITER is addressed.

  15. Coating considerations for mirrors of CPV devices

    SciTech Connect

    Schmauder, Torsten; Sauer, Peter; Ickes, Gerd

    2014-09-26

    One of the different optical concepts for concentrator devices is to place a focussing primary mirror behind a transparent front plate. In addition (also in case of Fresnel-diffractive main optics), further 'secondary' reflectors may be used further along the beam path. Such mirrors are usually implemented as coating stacks of a highly reflective metal - usually silver - and protective layers. The protective layers are preferably designed as reflection enhancing interference stack. The design of such protective layer stacks yields two difficulties, which are addressed in this paper: (a) vacuum coating of three-dimensional parts will result in a thickness distribution and the optical design of the stack should thus be tolerant to layer thickness variations, and (b) different places of the mirror will have different angle-of-incidence of the sunlight under operating conditions. As result, the layer stack has a different design at different places of the mirror.

  16. Calibration and testing of the 6.5 m MMT adaptive optics system

    NASA Astrophysics Data System (ADS)

    Johnson, Robert Lee

    2001-10-01

    This dissertation describes the development, calibration, and testing of the adaptive optics system for the 6.5 m Multiple Mirror Telescope. By employing a deformable secondary mirror, the MMT adaptive optics system uniquely solves several problems typical of astronomical adaptive optics systems. Extra components are eliminated, improving throughput and reducing emissivity. Since the adaptive secondary is integral to the telescope, a corrected beam is presented to any instrument mounted at Cassegrain focus. The testing of an adaptive mirror, which is large and convex, poses a new and difficult problem. I present a test apparatus that allows complete calibration and operation, in closed-loop, of the entire adaptive optics system in the laboratory. The test apparatus replicates the optical path of the telescope with a wavefront error of less than 500 nm RMS. To simulate atmospheric turbulence, machined acrylic plates are included. A phase-shifting interferometer allows calibration of the Shack-Hartmann wavefront sensor and reconstruction algorithms; comparisons agree to one-third of the root-mean-square wavefront. First, techniques were developed to align the apparatus and measure residual aberration. Then, the wavefront sensor was calibrated by measuring its response to introduced tilt. Lastly, a Fourier wave-optics approach was used to produce a modal wavefront reconstructor. The adaptive secondary mirror uses electro-magnetic force actuators. Capacitive position sensors are placed at each actuator to permit control of the mirror shape without measuring the reflected wavefront. These sensors have nanometer resolution, but require calibration. To calibrate the sensors, I developed a small optical instrument which measures the thickness of transparent films to an absolute accuracy of 5 nm with a precision of 2 nm. The device has applications far beyond the scope of this research. Twenty-four of these optical gap sensors have been built to calibrate the 336 capacitive

  17. The Chilled-Mirror Humidity Sensor: Improved Radiosonde Measurements

    NASA Technical Reports Server (NTRS)

    Schmidlin, F. J.

    1999-01-01

    Chilled-mirror humidity sensor technology recently was adapted for use with the VIZ radiosonde. The principle of the chilled-mirror operation is to lower its temperature until dew forms on the mirror, at that point the dew point temperature is noted and the mirror is then heated to evaporate the moisture. The cycle is repeated. Research conducted from NASA's Wallops Flight Facility has provided comparisons between the chilled-mirror sensor and the carbon hygristor of VIZ, and the capacitive sensors of AIR Inc. and Vaisala Co. We believe the chilled-mirror sensor is accurate and would serve as a reference standard for evaluating operational radiosonde relative humidity sensors. Thus, differences seen in the comparisons are beginning to furnish insight into developing better humidity sensors. We discuss these comparison results as well as reproducibility results from a dual chilled-mirror measurement.

  18. Water Cooled Mirror Design

    SciTech Connect

    Dale, Gregory E.; Holloway, Michael Andrew; Pulliam, Elias Noel

    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.

  19. Integral Flexure Mounts for Metal Mirrors for Cryogenic Use

    NASA Technical Reports Server (NTRS)

    Zewari, S. Wahid; Hylan, Jason E.; Irish, Sandra M.; Ohl, Raymond G.; Conkey, Shelly B.

    2006-01-01

    Semi-kinematic, six-degree-of-freedom flexure mounts have been incorporated as integral parts of metal mirrors designed to be used under cryogenic conditions as parts of an astronomical instrument. The design of the mirrors and their integral flexure mounts can also be adapted to other instruments and other operating temperatures. In comparison with prior kinematic cryogenic mirror mounts, the present mounts are more compact and can be fabricated easily using Ram-EDM (electrical discharge machining) process

  20. Specific temperature-induced perturbations of secondary mRNA structures are associated with the cold-adapted temperature-sensitive phenotype of influenza A virus

    PubMed Central

    Chursov, Andrey; Kopetzky, Sebastian J.; Leshchiner, Ignaty; Kondofersky, Ivan; Theis, Fabian J.; Frishman, Dmitrij; Shneider, Alexander

    2012-01-01

    For decades, cold-adapted, temperature-sensitive (ca/ts) strains of influenza A virus have been used as live attenuated vaccines. Due to their great public health importance it is crucial to understand the molecular mechanism(s) of cold adaptation and temperature sensitivity that are currently unknown. For instance, secondary RNA structures play important roles in influenza biology. Thus, we hypothesized that a relatively minor change in temperature (32–39°C) can lead to perturbations in influenza RNA structures and, that these structural perturbations may be different for mRNAs of the wild type (wt) and ca/ts strains. To test this hypothesis, we developed a novel in silico method that enables assessing whether two related RNA molecules would undergo (dis)similar structural perturbations upon temperature change. The proposed method allows identifying those areas within an RNA chain where dissimilarities of RNA secondary structures at two different temperatures are particularly pronounced, without knowing particular RNA shapes at either temperature. We identified such areas in the NS2, PA, PB2 and NP mRNAs. However, these areas are not identical for the wt and ca/ts mutants. Differences in temperature-induced structural changes of wt and ca/ts mRNA structures may constitute a yet unappreciated molecular mechanism of the cold adaptation/temperature sensitivity phenomena. PMID:22995831

  1. Adapting to the System or the Student? Exploring Teacher Adaptations to Disadvantaged Students in an English and a Belgian Secondary School

    ERIC Educational Resources Information Center

    Stevens, Peter A. J.; Van Houtte, Mieke

    2011-01-01

    This article builds on research on teacher adaptations to students by exploring how Belgian and English national contexts influence teachers' definitions of educational success, their explanations of educational failure, and their allocation of scarce educational resources to disadvantaged students. Ethnographic data from one Flemish (Belgian) and…

  2. Manufacturing of the ESO adaptive optics facility

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  3. LOXT mirror design study

    NASA Technical Reports Server (NTRS)

    Vanspeybroeck, L.; Antrim, W.; Boyd, D.; Giacconi, R.; Sinnamon, G.; Stille, F.

    1972-01-01

    The final report for the large orbiting X-ray telescope (LOXT) high resolution mirror design study is presented. The following tasks were performed: (1) Generation of a reference and alternate preliminary design for the LOXT high resolution mirror assembly, which will meet the LOXT scientific requirements, and are within the present state of the art of materials and fabrication techniques. (2) Measurement, in X-rays, of the scattering properties of a variety of optical flats, embodying materials, coatings, and polishing techniques which might be applicable to the flight configuration LOXT high resolution mirror. (3) Preparation of a procurement specification for a paraboloid test mirror of the size of the innermost paraboloid of the high resolution mirror assembly, including the design requirements for the reference design evolved from this preliminary design study. The results of the engineering and scientific analysis and the conclusions drawn are presented. The procurement specification for the test mirror is included.

  4. Erected mirror optical switch

    DOEpatents

    Allen, James J.

    2005-06-07

    A microelectromechanical (MEM) optical switching apparatus is disclosed that is based on an erectable mirror which is formed on a rotatable stage using surface micromachining. An electrostatic actuator is also formed on the substrate to rotate the stage and mirror with a high angular precision. The mirror can be erected manually after fabrication of the device and used to redirect an incident light beam at an arbitrary angel and to maintain this state in the absence of any applied electrical power. A 1.times.N optical switch can be formed using a single rotatable mirror. In some embodiments of the present invention, a plurality of rotatable mirrors can be configured so that the stages and mirrors rotate in unison when driven by a single micromotor thereby forming a 2.times.2 optical switch which can be used to switch a pair of incident light beams, or as a building block to form a higher-order optical switch.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Impact of Adaptive Materials on Teachers and their Students with Visual Impairments in Secondary Science and Mathematics Classes

    NASA Astrophysics Data System (ADS)

    Rule, Audrey C.; Stefanich, Greg P.; Boody, Robert M.; Peiffer, Belinda

    2011-04-01

    Science, technology, engineering, and mathematics (STEM) fields, important in today's world, are underrepresented by students with disabilities. Students with visual impairments, although cognitively similar to sighted peers, face challenges as STEM subjects are often taught using visuals. They need alternative forms of access such as enlarged or audio-converted text, tactile graphics, and involvement in hands-on science. This project focused on increasing teacher awareness of and providing funds for the purchase of supplemental adaptive resources, supplies, and equipment. We examined attitude and instructional changes across the year of the programme in 15 science and mathematics teachers educating students with visual impairments. Positive changes were noted from pretest to posttest in student and teacher perspectives, and in teacher attitudes towards students with disabilities in STEM classes. Teachers also provided insights into their challenges and successes through a reflective narrative. Several adolescent students resisted accommodations to avoid appearing conspicuous to peers. Teachers implemented three strategies to address this: providing the adaptations to all students in the class; convincing the student of the need for adaptation; and involving the class in understanding and accepting the student's impairment. A variety of teacher-created adaptations for various science and mathematics labs are reported. Another finding was many adaptations provided for the student with visual impairment benefitted the entire class. This study supports the claim that given knowledgeable, supportive teachers, and with appropriate accommodations such as tactile or auditory materials, students with visual impairments can be as successful and engaged as other students in science and mathematics.

  7. Using intervention mapping to develop and adapt a secondary stroke prevention program in Veterans Health Administration medical centers

    PubMed Central

    2010-01-01

    Secondary stroke prevention is championed by the stroke guidelines; however, it is rarely systematically delivered. We sought to develop a locally tailored, evidence-based secondary stroke prevention program. The purpose of this paper was to apply intervention mapping (IM) to develop our locally tailored stroke prevention program and implementation plan. We completed a needs assessment and the five Steps of IM. The needs assessment included semi-structured interviews of 45 providers; 26 in Indianapolis and 19 in Houston. We queried frontline clinical providers of stroke care using structured interviews on the following topics: current provider practices in secondary stroke risk factor management; barriers and needs to support risk factor management; and suggestions on how to enhance secondary stroke risk factor management throughout the continuum of care. We then describe how we incorporated each of the five Steps of IM to develop locally tailored programs at two sites that will be evaluated through surveys for patient outcomes, and medical records chart abstraction for processes of care. PMID:21159171

  8. Castable Amorphous Metal Mirrors and Mirror Assemblies

    NASA Technical Reports Server (NTRS)

    Hofmann, Douglas C.; Davis, Gregory L.; Agnes, Gregory S.; Shapiro, Andrew A.

    2013-01-01

    A revolutionary way to produce a mirror and mirror assembly is to cast the entire part at once from a metal alloy that combines all of the desired features into the final part: optical smoothness, curvature, flexures, tabs, isogrids, low CTE, and toughness. In this work, it has been demonstrated that castable mirrors are possible using bulk metallic glasses (BMGs, also called amorphous metals) and BMG matrix composites (BMGMCs). These novel alloys have all of the desired mechanical and thermal properties to fabricate an entire mirror assembly without machining, bonding, brazing, welding, or epoxy. BMGs are multi-component metal alloys that have been cooled in such a manner as to avoid crystallization leading to an amorphous (non-crystalline) microstructure. This lack of crystal structure and the fact that these alloys are glasses, leads to a wide assortment of mechanical and thermal properties that are unlike those observed in crystalline metals. Among these are high yield strength, carbide-like hardness, low melting temperatures (making them castable like aluminum), a thermoplastic processing region (for improving smoothness), low stiffness, high strength-to-weight ratios, relatively low CTE, density similar to titanium alloys, high elasticity and ultra-smooth cast parts (as low as 0.2-nm surface roughness has been demonstrated in cast BMGs). BMGMCs are composite alloys that consist of a BMG matrix with crystalline dendrites embedded throughout. BMGMCs are used to overcome the typically brittle failure observed in monolithic BMGs by adding a soft phase that arrests the formation of cracks in the BMG matrix. In some cases, BMGMCs offer superior castability, toughness, and fatigue resistance, if not as good a surface finish as BMGs. This work has demonstrated that BMGs and BMGMCs can be cast into prototype mirrors and mirror assemblies without difficulty.

  9. NFIRAOS: TMT narrow field near-infrared facility adaptive optics

    NASA Astrophysics Data System (ADS)

    Herriot, Glen; Hickson, Paul; Ellerbroek, B. L.; Andersen, D. A.; Davidge, T.; Erickson, D. A.; Powell, I. P.; Clare, R.; Gilles, L.; Boyer, C.; Smith, M.; Saddlemyer, L.; Véran, J.-P.

    2006-06-01

    Although many of the instruments planned for the TMT (Thirty Meter Telescope) have their own closely-coupled adaptive optics systems, TMT will also have a facility Adaptive Optics (AO) system, NFIRAOS, feeding three instruments on the Nasmyth platform. This Narrow-Field Infrared Adaptive Optics System, employs conventional deformable mirrors with large diameters of about 300 mm. The requirements for NFIRAOS include 1.0-2.5 microns wavelength range, 30 arcsecond diameter science field of view (FOV), excellent sky coverage, and diffraction-limited atmospheric turbulence compensation (specified at 133 nm RMS including residual telescope and science instrument errors.) The reference design for NFIRAOS includes six sodium laser guide stars over a 70 arcsecond FOV, and multiple infrared tip/tilt sensors and a natural guide star focus sensor within instruments. Larger telescopes require greater deformable mirror (DM) stroke. Although initially NFIRAOS will correct a 10 arcsecond science field, it uses two deformable mirrors in series, partly to provide sufficient stroke for atmospheric correction over the 30 m telescope aperture, but mainly to improve sky coverage by sharpening near-IR natural guide stars over a 2 arcminute diameter "technical" field. The planned upgrade to full performance includes replacing the ground-conjugated DM with a higher actuator density, and using a deformable telescope secondary mirror as a "woofer." NFIRAOS feeds three live instruments: a near-Infrared integral field Imaging spectrograph, a near-infrared echelle spectrograph, and after upgrading NFIRAOS to full multi-conjugation, a wide field (30 arcsecond) infrared camera.

  10. Adaptation and Validation of the Course Experience Questionnaire in the Context of Post-Secondary Education in Hong Kong

    ERIC Educational Resources Information Center

    Law, Dennis C. S.; Meyer, Jan H. F.

    2011-01-01

    Purpose: The Course Experience Questionnaire (CEQ) is a quantitative instrument for collecting student feedback on programme quality that has been tested and practically used in Western university response-contexts. The purpose of this paper is to adapt and partially validate a Chinese translation of the CEQ, for application in the new context of…

  11. Assessing Motivation to Learn Chemistry: Adaptation and Validation of Science Motivation Questionnaire II with Greek Secondary School Students

    ERIC Educational Resources Information Center

    Salta, Katerina; Koulougliotis, Dionysios

    2015-01-01

    In educational research, the availability of a validated version of an original instrument in a different language offers the possibility for valid measurements obtained within the specific educational context and in addition it provides the opportunity for valid cross-cultural comparisons. The present study aimed to adapt the Science Motivation…

  12. Infinite impulse response modal filtering in visible adaptive optics

    NASA Astrophysics Data System (ADS)

    Agapito, G.; Arcidiacono, C.; Quirós-Pacheco, F.; Puglisi, A.; Esposito, S.

    2012-07-01

    Diffraction limited resolution adaptive optics (AO) correction in visible wavelengths requires a high performance control. In this paper we investigate infinite impulse response filters that optimize the wavefront correction: we tested these algorithms through full numerical simulations of a single-conjugate AO system comprising an adaptive secondary mirror with 1127 actuators and a pyramid wavefront sensor (WFS). The actual practicability of the algorithms depends on both robustness and knowledge of the real system: errors in the system model may even worsen the performance. In particular we checked the robustness of the algorithms in different conditions, proving that the proposed method can reject both disturbance and calibration errors.

  13. Stable mirror mount

    DOEpatents

    Cutburth, Ronald W.

    1990-01-01

    An improved mirror mount assembly is disclosed. The mirror mount assembly provides a post assembly slidable in a Y-axis orientation and a nut plate assembly slidable in an X-axis orientation and a device for simultaneously locking the post assembly and the key assembly in a fixed position.

  14. Stable mirror mount

    DOEpatents

    Cutburth, R.W.

    1983-11-04

    An improved mirror mount assembly is disclosed. The mirror mount assembly provides a post assembly slidable in a Y-axis orientation and a nut plate assembly slidable in an X-axis orientation and means for simultaneously locking said post assembly and said key assembly in a fixed position.

  15. Bronze rainbow hologram mirrors

    NASA Astrophysics Data System (ADS)

    Dawson, P.

    2006-02-01

    This project draws on holographic embossing techniques, ancient artistic conventions of bronze mirror design and modelling and casting processes to accomplish portraiture of reflection. Laser scanning, 3D computer graphics and holographic imaging are employed to enable a permanent 3D static holographic image to appear integrated with the real-time moving reflection of a viewer's face in a polished bronze disc. The disc and the figure which holds it (caryatid) are cast in bronze from a lost wax model, a technique which has been used for millennia to make personal mirrors. The Caryatid form of bronze mirror which went through many permutations in ancient Egyptian, Greece and Rome shows a plethora of expressive figure poses ranging from sleek nudes to highly embellished multifigure arrangements. The prototype of this series was made for Australian choreographer Graeme Murphy, Artistic Director of the Sydney Dance Company. Each subsequent mirror will be unique in figure and holographic imagery as arranged between artist and subject. Conceptually this project references both the modern experience of viewing mirrors retrieved from ancient tombs, which due to deterioration of the surface no longer reflect, and the functioning of Chinese Magic mirrors, which have the ability to project a predetermined image. Inspired by the metaphorical potential of these mirrors, which do not reflect the immediate reality of the viewer, this bronze hologram mirror series enables each viewer to reflect upon himself or herself observing simultaneously the holographic image and their own partially obliterated reflection.

  16. A Resource for Eliciting Student Alternative Conceptions: Examining the Adaptability of a Concept Inventory for Natural Selection at the Secondary School Level

    NASA Astrophysics Data System (ADS)

    Lucero, Margaret M.; Petrosino, Anthony J.

    2016-07-01

    The Conceptual Inventory of Natural Selection (CINS) is an example of a research-based instrument that assesses conceptual understanding in an area that contains well-documented alternative conceptions. Much of the CINS's use and original validation has been relegated to undergraduate settings, but the information learned from student responses on the CINS can also potentially be a useful resource for teachers at the secondary level. Because of its structure, the CINS can have a role in eliciting alternative conceptions and induce deeper conceptual understanding by having student ideas leveraged during instruction. In a first step toward this goal, the present study further investigated the CINS's internal properties by having it administered to a group (n = 339) of students among four different biology teachers at a predominantly Latino, economically disadvantaged high school. In addition, incidences of the concept inventory's use among the teachers' practices were collected for support of its adaptability at the secondary level. Despite the teachers' initial enthusiasm for the CINS's use as an assessment tool in the present study, results from a principal components analysis demonstrate inconsistencies between the original and present validations. Results also reveal how the teachers think CINS items may be revised for future use among secondary student populations.

  17. Partially segmented deformable mirror

    DOEpatents

    Bliss, Erlan S.; Smith, James R.; Salmon, J. Thaddeus; Monjes, Julio A.

    1991-01-01

    A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp.

  18. Partially segmented deformable mirror

    DOEpatents

    Bliss, E.S.; Smith, J.R.; Salmon, J.T.; Monjes, J.A.

    1991-05-21

    A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp. 5 figures.

  19. Tandem mirror plasma confinement apparatus

    DOEpatents

    Fowler, T. Kenneth

    1978-11-14

    Apparatus and method for confining a plasma in a center mirror cell by use of two end mirror cells as positively charged end stoppers to minimize leakage of positive particles from the ends of the center mirror cell.

  20. Alignment Test Results of the JWST Pathfinder Telescope Mirrors in the Cryogenic Environment

    NASA Technical Reports Server (NTRS)

    Whitman, Tony L.; Wells, Conrad; Hadaway, James; Knight, J. Scott; Lunt, Sharon

    2016-01-01

    After integration of the Optical Telescope Element (OTE) to the Integrated Science Instrument Module (ISIM) to become the OTIS, the James Webb Space Telescope OTIS is tested at NASAs Johnson Space Center (JSC) in the cryogenic vacuum Chamber A for alignment and optical performance. The alignment of the mirrors comprises a sequence of steps as follows: The mirrors are coarsely aligned using photogrammetry cameras with reflective targets attached to the sides of the mirrors. Then a multi-wavelength interferometer is aligned to the 18-segment primary mirror using cameras at the center of curvature to align reflected light from the segments and using fiducials at the edge of the primary mirror. Once the interferometer is aligned, the 18 primary mirror segments are then adjusted to optimize wavefront error of the aggregate mirror. This process phases the piston and tilt positions of all the mirror segments. An optical fiber placed at the Cassegrain focus of the telescope then emits light towards the secondary mirror to create a collimated beam emitting from the primary mirror. Portions of the collimated beam are retro-reflected from flat mirrors at the top of the chamber to pass through the telescope to the SI detector. The image on the detector is used for fine alignment of the secondary mirror and a check of the primary mirror alignment using many of the same analysis techniques used in the on-orbit alignment. The entire process was practiced and evaluated in 2015 at cryogenic temperature with the Pathfinder telescope.

  1. Space Mirror Alignment System

    NASA Technical Reports Server (NTRS)

    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. Phase Adaptation and Correction by Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Tiziani, Hans J.

    2010-04-01

    Adaptive optical elements and systems for imaging or laser beam propagation are used for some time in particular in astronomy, where the image quality is degraded by atmospheric turbulence. In astronomical telescopes a deformable mirror is frequently used to compensate wavefront-errors due to deformations of the large mirror, vibrations as well as turbulence and hence to increase the image quality. In the last few years interesting elements like Spatial Light Modulators, SLM's, such as photorefractive crystals, liquid crystals and micro mirrors and membrane mirrors were introduced. The development of liquid crystals and micro mirrors was driven by data projectors as consumer products. They contain typically a matrix of individually addressable pixels of liquid crystals and flip mirrors respectively or more recently piston mirrors for special applications. Pixel sizes are in the order of a few microns and therefore also appropriate as active diffractive elements in digital holography or miniature masks. Although liquid crystals are mainly optimized for intensity modulation; they can be used for phase modulation. Adaptive optics is a technology for beam shaping and wavefront adaptation. The application of spatial light modulators for wavefront adaptation and correction and defect analysis as well as sensing will be discussed. Dynamic digital holograms are generated with liquid crystal devices (LCD) and used for wavefront correction as well as for beam shaping and phase manipulation, for instance. Furthermore, adaptive optics is very useful to extend the measuring range of wavefront sensors and for the wavefront adaptation in order to measure and compare the shape of high precision aspherical surfaces.

  3. The contribution of primary and secondary somatosensory cortices to the representation of body parts and body sides: an fMRI adaptation study.

    PubMed

    Tamè, Luigi; Braun, Christoph; Lingnau, Angelika; Schwarzbach, Jens; Demarchi, Gianpaolo; Li Hegner, Yiwen; Farnè, Alessandro; Pavani, Francesco

    2012-12-01

    Although the somatosensory homunculus is a classically used description of the way somatosensory inputs are processed in the brain, the actual contributions of primary (SI) and secondary (SII) somatosensory cortices to the spatial coding of touch remain poorly understood. We studied adaptation of the fMRI BOLD response in the somatosensory cortex by delivering pairs of vibrotactile stimuli to the finger tips of the index and middle fingers. The first stimulus (adaptor) was delivered either to the index or to the middle finger of the right or left hand, and the second stimulus (test) was always administered to the left index finger. The overall BOLD response evoked by the stimulation was primarily contralateral in SI and was more bilateral in SII. However, our fMRI adaptation approach also revealed that both somatosensory cortices were sensitive to ipsilateral as well as to contralateral inputs. SI and SII adapted more after subsequent stimulation of homologous as compared with nonhomologous fingers, showing a distinction between different fingers. Most importantly, for both somatosensory cortices, this finger-specific adaptation occurred irrespective of whether the tactile stimulus was delivered to the same or to different hands. This result implies integration of contralateral and ipsilateral somatosensory inputs in SI as well as in SII. Our findings suggest that SI is more than a simple relay for sensory information and that both SI and SII contribute to the spatial coding of touch by discriminating between body parts (fingers) and by integrating the somatosensory input from the two sides of the body (hands). PMID:22849401

  4. Mirror plasma apparatus

    DOEpatents

    Moir, Ralph W.

    1981-01-01

    A mirror plasma apparatus which utilizes shielding by arc discharge to form a blanket plasma and lithium walls to reduce neutron damage to the wall of the apparatus. An embodiment involves a rotating liquid lithium blanket for a tandem mirror plasma apparatus wherein the first wall of the central mirror cell is made of liquid lithium which is spun with angular velocity great enough to keep the liquid lithium against the first material wall, a blanket plasma preventing the lithium vapor from contaminating the plasma.

  5. Nanolaminate deformable mirrors

    DOEpatents

    Papavasiliou, Alexandros P.; Olivier, Scot S.

    2009-04-14

    A deformable mirror formed out of two layers of a nanolaminate foil attached to a stiff substrate is introduced. Deformation is provided by an electrostatic force between two of the layers. The internal stiffness of the structure allows for high-spatial-frequency shapes. The nanolaminate foil of the present invention allows for a high-quality mirror surface. The device achieves high precision in the vertical direction by using foils with accurately controlled thicknesses, but does not require high precision in the lateral dimensions, allowing such mirrors to be fabricated using crude lithography techniques. Such techniques allow structures up to about the meter scale to be fabricated.

  6. Nanolaminate deformable mirrors

    DOEpatents

    Papavasiliou, Alexandros P.; Olivier, Scot S.

    2010-04-06

    A deformable mirror formed out of two layers of a nanolaminate foil attached to a stiff substrate is introduced. Deformation is provided by an electrostatic force between two of the layers. The internal stiffness of the structure allows for high-spatial-frequency shapes. The nanolaminate foil of the present invention allows for a high-quality mirror surface. The device achieves high precision in the vertical direction by using foils with accurately controlled thicknesses, but does not require high precision in the lateral dimensions, allowing such mirrors to be fabricated using crude lithography techniques. Such techniques allow structures up to about the meter scale to be fabricated.

  7. NIF small mirror mount

    SciTech Connect

    McCarville, T

    1999-07-01

    A number of small mirror mounts have been identified that meet the stringent stability, wave front, and cleanliness standards of the NIF. These requirements are similar to those required in other performance critical optical design applications. Future design teams would conserve time and effort if recognized standards were established for mirror mount design and performance characteristics. Standards for stability, physical features, wave front distortion, and cleanliness would simplify the qualification process considerably. At this point such standards are not difficult to define, as the technical support work has been performed repeatedly by mirror mount consumers and suppliers.

  8. Controllable Mirror Devices

    NASA Technical Reports Server (NTRS)

    1992-01-01

    A deformable Mirror Device (DMD) is a type of spatial light modulator in which mirrors fabricated monolithically on a silicon chip are deformed, or tilted, under electronic control to change the direction of light that falls upon the mirror. NASA and Texas Instruments (TI) have worked to develop this technology, which has subsequently been commercialized by TI. Initial application is the DMD 2000 Travel Information Printer for high speed, high volume printing of airline tickets and boarding passes. Other possible applications range from real-time object tracking to advanced industrial machine vision systems.

  9. Using Principles of Complex Adaptive Systems to Implement Secondary Prevention of Coronary Heart Disease in Primary Care

    PubMed Central

    Kottke, Thomas E; Huebsch, Jacquelyn A; McGinnis, Paul; Nichols, Jolleen M; Parker, Emily D; Tillema, Juliana O; Maciosek, Michael V

    2016-01-01

    Context: Primary care practice. Objective: To test whether the principles of complex adaptive systems are applicable to implementation of team-based primary care. Design: We used complex adaptive system principles to implement team-based care in a private, five-clinic primary care practice. We compared randomly selected samples of patients with coronary heart disease (CHD) and diabetes before system implementation (March 1, 2009, to February 28, 2010) and after system implementation (December 1, 2011, to March 31, 2013). Main Outcome Measures: Rates of patients meeting the composite goals for CHD (blood pressure < 140/90 mmHg, low-density lipoprotein cholesterol level < 100 mg/dL, tobacco-free, and using aspirin unless contraindicated) and diabetes (CHD goal plus hemoglobin A1c concentration < 8%) before and after the intervention. We also measured provider and patient satisfaction with preventive services. Results: The proportion of patients with CHD who met the composite goal increased from 40.3% to 59.9% (p < 0.0001) because documented aspirin use increased (65.2%–97.5%, p < 0.0001) and attainment of the cholesterol goal increased (77.0%–83.9%, p = 0.0041). The proportion of diabetic patients meeting the composite goal rose from 24.5% to 45.4% (p < 0.0001) because aspirin use increased (58.6%–97.6%, p < 0.0001). Increased percentages of patients meeting the CHD and diabetes composite goals were not significantly different (p = 0.2319). Provider satisfaction with preventive services delivery increased significantly (p = 0.0017). Patient satisfaction improved but not significantly. Conclusion: Principles of complex adaptive systems can be used to implement team-based care systems for patients with CHD and possibly diabetic patients. PMID:26784851

  10. The Adaptive Optics Facility Module GRAAL on its Way to Final Validation

    NASA Astrophysics Data System (ADS)

    Arsenault, R.; Paufique, J.; Kolb, J.; Madec, P.-Y.; Kiekebusch, M.; Argomedo, J.; Jost, A.; Tordo, S.; Donaldson, R.; Suarez, M.; Conzelmann, R.; Kuntschner, H.; Siebenmorgen, R.; Kirchbauer, J.-P.; Rissmann, A.-G.; Schimpelsberger, J.

    2014-06-01

    The VLT Adaptive Optics Facility (AOF) module GRAAL has been developed to provide ground layer adaptive optics correction for the HAWK-I infrared imager. This will improve the limiting magnitude and promote science cases requiring better spatial resolution. The gain in resolution is comparable to selecting a better site for the telescope. The GRAAL wavefront sensor signals are processed by a SPARTA real-time computer that drives the AOF deformable secondary mirror integrated in an upgraded secondary mirror assembly on Yepun, the VLT Unit Telescope 4. The system test phase of GRAAL has started in the integration laboratory in Garching and is described; provisional acceptance is expected to take place at the end of 2014.

  11. Wide field adaptive optics correction for the GMT using natural guide stars

    NASA Astrophysics Data System (ADS)

    van Dam, Marcos A.; Bouchez, Antonin H.; McLeod, Brian A.

    2014-07-01

    The conceptual design of the Giant Magellan Telescope has four wavefront sensors used to maintain the shape and alignment of the segmented primary and secondary mirrors. In this paper, we show that by reading the sensors at 200 Hz, we can also compensate for low altitude turbulence. As a result, there is a large improvement in image quality, even at visible wavelengths, over the entire science field of view of the telescope. A minimum-variance reconstructor is presented that takes slope measurements from four stars of arbitrary location and magnitude and produces the optimal adaptive secondary mirror commands. The performance of the adaptive optics system in this mode is simulated using YAO, an end-to-end simulation tool. We present the results of trade studies performed to optimize the science return of the telescope.

  12. Metrology Arrangement for Measuring the Positions of Mirrors of a Submillimeter Telescope

    NASA Technical Reports Server (NTRS)

    Abramovici, Alex; Bartman, Randall K.

    2011-01-01

    The position of the secondary mirror of a submillimeter telescope with respect to the primary mirror needs to be known .0.03 mm in three dimensions. At the time of this reporting, no convenient, reasonably priced arrangement that offers this capability exists. The solution proposed here relies on measurement devices developed and deployed for the GeoSAR mission, and later adapted for the ISAT (Innovative Space Based Radar Antenna Technology) demonstration. The measurement arrangement consists of four metrology heads, located on an optical bench, attached to the secondary mirror. Each metrology head has a dedicated target located at the edge of the primary mirror. One laser beam, launched from the head and returned by the target, is used to measure distance. Another beam, launched from a beacon on the target, is monitored by the metrology head and generates a measurement of the target position in the plane perpendicular to the laser beam. A 100-MHz modulation is carried by a collimated laser beam. The relevant wavelength is the RF one, 3 m, divided by two, because the light carries it to the target and back. The phase change due to travel to the target and back is measured by timing the zero-crossing of the RF modulation, using a 100-MHz clock. In order to obtain good resolution, the 100-MHz modulation signal is down-converted to 1 kHz. Then, the phase change corresponding to the round-trip to the target is carried by a 1-kHz signal. Since the 100-MHz clock beats 100,000 times during one period of the 1-kHz signal, the least-significant-bit (LSB) resolution is LSB = 0.015 mm.

  13. Secondary contact and local adaptation contribute to genome-wide patterns of clinal variation in Drosophila melanogaster.

    PubMed

    Bergland, Alan O; Tobler, Ray; González, Josefa; Schmidt, Paul; Petrov, Dmitri

    2016-03-01

    Populations arrayed along broad latitudinal gradients often show patterns of clinal variation in phenotype and genotype. Such population differentiation can be generated and maintained by both historical demographic events and local adaptation. These evolutionary forces are not mutually exclusive and can in some cases produce nearly identical patterns of genetic differentiation among populations. Here, we investigate the evolutionary forces that generated and maintain clinal variation genome-wide among populations of Drosophila melanogaster sampled in North America and Australia. We contrast patterns of clinal variation in these continents with patterns of differentiation among ancestral European and African populations. Using established and novel methods we derive here, we show that recently derived North America and Australia populations were likely founded by both European and African lineages and that this hybridization event likely contributed to genome-wide patterns of parallel clinal variation between continents. The pervasive effects of admixture mean that differentiation at only several hundred loci can be attributed to the operation of spatially varying selection using an FST outlier approach. Our results provide novel insight into the well-studied system of clinal differentiation in D. melanogaster and provide a context for future studies seeking to identify loci contributing to local adaptation in a wide variety of organisms, including other invasive species as well as temperate endemics. PMID:26547394

  14. Composite Material Mirror Testing

    NASA Technical Reports Server (NTRS)

    2000-01-01

    In this photograph, the composite material mirror is tested in the X-Ray Calibration Facility at the Marshall Space Flight Center for the James Webb Space Telescope (JWST). The mirror test conducted was to check the ability to accurately model and predict the cryogenic performance of complex mirror systems, and the characterization of cryogenic dampening properties of beryllium. The JWST, a next generation successor to the Hubble Space Telescope (HST), was named in honor of James W. Webb, NASA's second administrator, who led NASA in the early days of the fledgling Aerospace Agency. Scheduled for launch in 2010 aboard an expendable launch vehicle, the JWST will be able to look deeper into the universe than the HST because of the increased light-collecting power of its larger mirror and the extraordinary sensitivity of its instrument to infrared light.

  15. JWST Mirror Installation

    NASA Video Gallery

    The first six of 18 hexagonal shaped segments that will form NASA’s James Webb Space Telescope’s primary mirror for space observations were readied this week to begin final cryogenic testing at...

  16. The Rotating Mirror.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    1981-01-01

    Discusses theory of the rotating mirror, its use in measuring the velocity of the electrical signal in wires, and the velocity of light. Concludes with a description of the manometric flame apparatus developed for analyzing sound waves. (SK)

  17. Mirror Technology Roadmap

    NASA Technical Reports Server (NTRS)

    Stahl, H. Phil

    2006-01-01

    NASA's Mirror Technology Roadmap identifies specific capabilities requiring significant advances in optical fabrication and testing to enable the next generation of large-aperture space telescopes for astronomy and Earth science missions ranging from x-ray to infrared.

  18. DIFFRACTION-LIMITED VISIBLE LIGHT IMAGES OF ORION TRAPEZIUM CLUSTER WITH THE MAGELLAN ADAPTIVE SECONDARY ADAPTIVE OPTICS SYSTEM (MagAO)

    SciTech Connect

    Close, L. M.; Males, J. R.; Morzinski, K.; Kopon, D.; Follette, K.; Rodigas, T. J.; Hinz, P.; Wu, Y-L.; Puglisi, A.; Esposito, S.; Riccardi, A.; Pinna, E.; Xompero, M.; Briguglio, R.; Uomoto, A; Hare, T.

    2013-09-10

    We utilized the new high-order (250-378 mode) Magellan Adaptive Optics system (MagAO) to obtain very high spatial resolution observations in ''visible light'' with MagAO's VisAO CCD camera. In the good-median seeing conditions of Magellan (0.''5-0.''7), we find MagAO delivers individual short exposure images as good as 19 mas optical resolution. Due to telescope vibrations, long exposure (60 s) r' (0.63 {mu}m) images are slightly coarser at FWHM = 23-29 mas (Strehl {approx}28%) with bright (R < 9 mag) guide stars. These are the highest resolution filled-aperture images published to date. Images of the young ({approx}1 Myr) Orion Trapezium {theta}{sup 1} Ori A, B, and C cluster members were obtained with VisAO. In particular, the 32 mas binary {theta}{sup 1} Ori C{sub 1} C{sub 2} was easily resolved in non-interferometric images for the first time. The relative positions of the bright trapezium binary stars were measured with {approx}0.6-5 mas accuracy. We are now sensitive to relative proper motions of just {approx}0.2 mas yr{sup -1} ({approx}0.4 km s{sup -1} at 414 pc)-this is a {approx}2-10 Multiplication-Sign improvement in orbital velocity accuracy compared to previous efforts. For the first time, we see clear motion of the barycenter of {theta}{sup 1} Ori B{sub 2} B{sub 3} about {theta}{sup 1} Ori B{sub 1}. All five members of the {theta}{sup 1} Ori B system appear likely to be a gravitationally bound ''mini cluster'', but we find that not all the orbits can be both circular and co-planar. The lowest mass member of the {theta}{sup 1} Ori B system (B{sub 4}; mass {approx}0.2 M{sub Sun }) has a very clearly detected motion (at 4.1 {+-} 1.3 km s{sup -1}; correlation = 99.9%) w.r.t. B{sub 1}. Previous work has suggested that B{sub 4} and B{sub 3} are on long-term unstable orbits and will be ejected from this ''mini cluster''. However, our new ''baseline'' model of the {theta}{sup 1} Ori B system suggests a more hierarchical system than previously thought, and so

  19. Towards a better mirror

    NASA Technical Reports Server (NTRS)

    Hoffer, David

    1987-01-01

    Telesat's Getaway Special competition was designed to promote interest in space among high school students in Canada. The winning entry proposed the manufacture of mirrors in microgravity and to compare the optical properties of these mirrors with similar ones made on Earth. Telesat engineers designed and built the experiment which flew on the Atlantic shuttle on November 27, 1985. This paper outlines the design evolution, its implementation, the manufacture and test of the GAS and the results of the experiment.

  20. Dual-use bimorph deformable mirrors

    NASA Astrophysics Data System (ADS)

    Griffith, M. S.; Laycock, L. C.; Bagshaw, J. M.; Rowe, D.

    2005-11-01

    Adaptive Optics (AO) is a critical underpinning technology for future optical countermeasures, laser delivery, target illumination and imaging systems. It measures and compensates for optical distortion caused by transmission through the atmosphere, resulting in the ability to deploy smaller lasers and identify targets at greater ranges. AO is also well established in ground based astronomy, and is finding applications in free space optical communications and ophthalmology. One of the key components in an AO system is the wavefront modifier, which acts on the incoming or outgoing beam to counter the effects of the atmosphere. BAE SYSTEMS ATC is developing multi-element Deformable Bimorph Mirrors (DBMs) for such applications. A traditional bimorph deformable mirror uses a set of edge electrodes outside the active area in order to meet the required boundary conditions for the active aperture. This inflicts a significant penalty in terms of bandwidth, which is inversely proportional to the square of the full mirror diameter. We have devised a number of novel mounting arrangements that reduce dead space and thus provide a much improved trade-off between bandwidth and stroke. These schemes include a novel method for providing vertical displacement at the periphery of the aperture, a method for providing a continuous compliant support underneath the bimorph mirror, and a method for providing a three point support underneath the bimorph. In all three cases, there is no requirement for edge electrodes to provide the boundary conditions, resulting in devices of much higher bandwidth. The target is to broaden the use of these types of mirror beyond the current limits of either low order/low bandwidth, to address the high order, high bandwidth systems required by long range, horizontal path applications. This paper will discuss the different mirror designs, and present experimental results for the most recently assembled mirrors.

  1. Notes on moving mirrors

    SciTech Connect

    Obadia, N.; Parentani, R.

    2001-08-15

    The Davies-Fulling (DF) model describes the scattering of a massless field by a noninertial mirror in two dimensions. In this paper, we generalize this model in two different ways. First, we consider partially reflecting mirrors. We show that the Bogoliubov coefficients relating inertial modes can be expressed in terms of the reflection factor and the transformation from inertial modes to modes at rest with respect to the mirror. In this perspective, the DF model is simply the limiting case when the reflection factor is unity for all frequencies. In the second part, we introduce an alternative model which is based on self-interactions described by an action principle. When the coupling is constant, this model can be solved exactly and gives rise to a partially reflecting mirror. The usefulness of this dynamical model lies in the possibility of switching off the coupling between the mirror and field. This allows us to obtain regularized expressions for the fluxes in situations where they are singular when using the DF model. Two examples are considered. The first concerns the flux induced by the disappearance of the reflection condition, a situation which bears some analogies with the end of the evaporation of a black hole. The second case concerns the flux emitted by a uniformly accelerated mirror.

  2. Genomics of Sponge-Associated Streptomyces spp. Closely Related to Streptomyces albus J1074: Insights into Marine Adaptation and Secondary Metabolite Biosynthesis Potential

    PubMed Central

    Ian, Elena; Malko, Dmitry B.; Sekurova, Olga N.; Bredholt, Harald; Rückert, Christian; Borisova, Marina E.; Albersmeier, Andreas; Kalinowski, Jörn; Gelfand, Mikhail S.; Zotchev, Sergey B.

    2014-01-01

    A total of 74 actinomycete isolates were cultivated from two marine sponges, Geodia barretti and Phakellia ventilabrum collected at the same spot at the bottom of the Trondheim fjord (Norway). Phylogenetic analyses of sponge-associated actinomycetes based on the 16S rRNA gene sequences demonstrated the presence of species belonging to the genera Streptomyces, Nocardiopsis, Rhodococcus, Pseudonocardia and Micromonospora. Most isolates required sea water for growth, suggesting them being adapted to the marine environment. Phylogenetic analysis of Streptomyces spp. revealed two isolates that originated from different sponges and had 99.7% identity in their 16S rRNA gene sequences, indicating that they represent very closely related strains. Sequencing, annotation, and analyses of the genomes of these Streptomyces isolates demonstrated that they are sister organisms closely related to terrestrial Streptomyces albus J1074. Unlike S. albus J1074, the two sponge streptomycetes grew and differentiated faster on the medium containing sea water. Comparative genomics revealed several genes presumably responsible for partial marine adaptation of these isolates. Genome mining targeted to secondary metabolite biosynthesis gene clusters identified several of those, which were not present in S. albus J1074, and likely to have been retained from a common ancestor, or acquired from other actinomycetes. Certain genes and gene clusters were shown to be differentially acquired or lost, supporting the hypothesis of divergent evolution of the two Streptomyces species in different sponge hosts. PMID:24819608

  3. Demonstration of a robust curved carbon fiber reinforced polymer deformable mirror with low surface error

    NASA Astrophysics Data System (ADS)

    Coughenour, Blake; Ammons, S. Mark; Hart, Michael; Romeo, Robert; Martin, Robert; Rademacher, Matt; Bailey, Hop

    2010-07-01

    Carbon fiber reinforced polymer (CFRP) composites provide several advantages as a substrate for thin-shell adaptive secondary mirrors, including high stiffness-to-weight ratio and low coefficient of thermal expansion (CTE). We have addressed some of these concerns using a prototype CFRP mirror under actuation. Using 4D and Newton interferometry, we present measurements of surface quality at a range of temperatures. Under actuator relaxation at room temperature, its surface error is low (92 nm RMS) and dominated by edge curvature. This error is reduced further under best actuator correction to 43 nm RMS, placing it into consideration for use in near-IR astronomy. The low surface error internal to the outer ring of actuators - 17 nm RMS at 60°F and 33 nm RMS at 20°F - suggests that larger mirrors will have a similar figure quality under actuator correction on ground-based AO systems. Furthermore, the actuator forces required to correct the figure are small compared to the dynamic range of voice coil actuators (~0.1 N). In addition, surface roughness is characterized to address the effects of high spatial frequency errors.

  4. SYMTRAN - A Time-dependent Symmetric Tandem Mirror Transport Code

    SciTech Connect

    Hua, D; Fowler, T

    2004-06-15

    A time-dependent version of the steady-state radial transport model in symmetric tandem mirrors in Ref. [1] has been coded up and first tests performed. Our code, named SYMTRAN, is an adaptation of the earlier SPHERE code for spheromaks, now modified for tandem mirror physics. Motivated by Post's new concept of kinetic stabilization of symmetric mirrors, it is an extension of the earlier TAMRAC rate-equation code omitting radial transport [2], which successfully accounted for experimental results in TMX. The SYMTRAN code differs from the earlier tandem mirror radial transport code TMT in that our code is focused on axisymmetric tandem mirrors and classical diffusion, whereas TMT emphasized non-ambipolar transport in TMX and MFTF-B due to yin-yang plugs and non-symmetric transitions between the plugs and axisymmetric center cell. Both codes exhibit interesting but different non-linear behavior.

  5. A large stroke magnetic fluid deformable mirror for focus control

    NASA Astrophysics Data System (ADS)

    Min, Ling-kun; Wu, Zhi-zheng; Huang, Ming-shuang; Kong, Xiang-hui

    2016-03-01

    A liquid deformable mirror, which can provide a large stroke deflection more than 100 μm, is proposed for focus control. The deformable mirror utilizes the concept of magnetic fluid deformation shaped with electromagnetic fields to achieve concave or convex surface and to change the optical focus depth of the mirrors. The free surface of the magnetic fluid is coated with a thin layer of metal-liquid-like film (MELLF) prepared from densely packed silver nanoparticles to enhance the reflectance of the deformable mirror. The experimental results on the fabricated prototype magnetic fluid deformable mirror (MFDM) show that the desired concave/convex surface shape can be controlled precisely with a closed-loop adaptive optical system.

  6. Analysis of a combined tip-tilt and deformable mirror.

    PubMed

    Wilcox, Christopher C; Andrews, Jonathan R; Restaino, Sergio R; Teare, Scott W; Payne, Don M; Krishna, Sanjay

    2006-03-15

    A deformable mirror mounted on a two-axis tilt platform can provide wavefront compensation at a single location in an adaptive optics system, resulting in a significant reduction in the number of optical components in the system and in a simplification of the alignment. However, the moment of inertia of a deformable mirror is significantly different from that of the monolithic mirror commonly mounted on a tilt platform. We report on what are to our knowledge the first experimental results of mounting a microelectromechanical deformable mirror onto a fast steering platform and the first observation that at low operating frequencies high-order deformation of the deformable mirror membrane was not recorded. PMID:16544588

  7. Actuated Hybrid Mirror Telescope

    NASA Technical Reports Server (NTRS)

    Hickey, Gregory; Redding, David; Lowman, Andrew; Cohen, David; Ohara, Catherine

    2005-01-01

    The figure depicts the planned Actuated Hybrid Mirror Telescope (AHMT), which is intended to demonstrate a new approach to the design and construction of wide-aperture spaceborne telescopes for astronomy and Earth science. This technology is also appropriate for Earth-based telescopes. The new approach can be broadly summarized as using advanced lightweight mirrors that can be manufactured rapidly at relatively low cost. More specifically, it is planned to use precise replicated metallic nanolaminate mirrors to obtain the required high-quality optical finishes. Lightweight, dimensionally stable silicon carbide (SiC) structures will support the nanolaminate mirrors in the required surface figures. To enable diffraction- limited telescope performance, errors in surface figures will be corrected by use of mirror-shape-control actuators that will be energized, as needed, by a wave-front-sensing and control system. The concepts of nanolaminate materials and mirrors made from nanolaminate materials were discussed in several previous NASA Tech Briefs articles. Nanolaminates constitute a relatively new class of materials that can approach theoretical limits of stiffness and strength. Nanolaminate mirrors are synthesized by magnetron sputter deposition of metallic alloys and/or compounds on optically precise master surfaces to obtain optical-quality reflector surfaces backed by thin shell structures. As an integral part of the deposition process, a layer of gold that will constitute the reflective surface layer is deposited first, eliminating the need for a subsequent and separate reflective-coating process. The crystallographic textures of the nanolaminate will be controlled to optimize the performance of the mirror. The entire deposition process for making a nanolaminate mirror takes less than 100 hours, regardless of the mirror diameter. Each nanolaminate mirror will be bonded to its lightweight SiC supporting structure. The lightweight nanolaminate mirrors and Si

  8. Helically linked mirror arrangement

    SciTech Connect

    Ranjan, P.

    1986-08-01

    A scheme is described for helical linking of mirror sections, which endeavors to combine the better features of toroidal and mirror devices by eliminating the longitudinal loss of mirror machines, having moderately high average ..beta.. and steady state operation. This scheme is aimed at a device, with closed magnetic surfaces having rotational transform for equilibrium, one or more axisymmetric straight sections for reduced radial loss, a simple geometrical axis for the links and an overall positive magnetic well depth for stability. We start by describing several other attempts at linking of mirror sections, made both in the past and the present. Then a description of our helically linked mirror scheme is given. This example has three identical straight sections connected by three sections having helical geometric axes. A theoretical analysis of the magnetic field and single-particle orbits in them leads to the conclusion that most of the passing particles would be confined in the device and they would have orbits independent of pitch angle under certain conditions. Numerical results are presented, which agree well with the theoretical results as far as passing particle orbits are concerned.

  9. Physics of mirror systems

    SciTech Connect

    Post, R.F.

    1982-05-01

    In recent years the emphasis in research on the magnetic mirror approach to fusion has been shifted to address what are essentially economically-motivated issues. The introduction of the Tandem Mirror idea solved in principal the problem of low Q (low fusion power gain) of mirror-based fusion systems. In order to optimize the tandem mirror idea from an economic standpoint, some important improvements have been suggested. These improvements include the thermal barrier idea of Baldwin and Logan and the axicell concept of Kesner. These new modifications introduce some special physics considerations. Among these are (1) The MHD stability properties of high energy electron components in the end cells; (2) The optimization of end-cell magnetic field configurations with the objective of minimizing equilibrium parallel currents; (3) The suppression of microstabilities by use of sloshing ion distributions. Following a brief outline of tandem mirror concepts, the above three topics are discussed, with illustrative examples taken from earlier work or from recent design studies.

  10. Innovative Magnetic Mirror Concepts

    NASA Astrophysics Data System (ADS)

    Simonen, Thomas

    2009-11-01

    In the past two decades, while magnetic mirror research in the US was curtailed, several innovations have been proposed and many have been demonstrated in Japan and Russia in the Gamma 10 and GDT experiments. These advances have led to new scientific understanding, means of overcoming previous short comings, and reconsideration of magnetic mirror systems as a modest size material testing neutron source or as a fusion- fission hybrid system. Compared to toroidal systems, the linear geometry of mirror systems has the significant advantages of easing construction, operation and maintenance, but has a less developed data base. The recent innovations include reliance on axi-symmetric mirror coils, suppression of energetic-ion cyclotron-modes with potential confined warm plasma, and sheared ExB flow stabilization of drift waves. To enable increased electron temperature, the magnetic field expansion ratio from the mirror to the end wall is increased beyond the square root of the ion to electron mass ratio. This expansion inhibits electron thermal conduction, reduces the incident wall power flux to low levels, and isolates plasma-wall interactions far from the confined plasma.

  11. The market of huge monolithic mirror substrates for optical astronomy

    NASA Astrophysics Data System (ADS)

    Döhring, Thorsten

    2013-09-01

    Professional astronomical telescopes are complex optical systems at the limit of technical feasibility. Often monolithic primary mirrors and sometimes even secondary mirrors with huge dimensions are used. Prominent examples are the two reflectors of the Large Binocular Telescope and the giant mirrors of VLT, GEMINI, and SUBARU. The performance of such precision optical components significantly depends on the physical parameters and the quality of their substrate materials. Within this paper selection criteria for mirror substrates will be discussed, thereby considering the important technical parameters as well as commercial points and aspects of project management. Qualities and limitations of classical mirror substrate materials like Zerodur, ULE, Sitall, borosilicate glass and Cervit will be evaluated and compared to new substrate materials like silicon carbide and beryllium. The different suppliers and their production processes are presented. In addition large mirrors of existing observatories and of telescopes under construction will be listed, thereby concentrating on mirrors above three meter in diameter. An outlook on material trends and on future astronomical telescopes closes this overview on the market of huge monolithic mirror substrates for optical astronomy.

  12. Cryogenic mirror analysis

    NASA Technical Reports Server (NTRS)

    Nagy, S.

    1988-01-01

    Due to extraordinary distances scanned by modern telescopes, optical surfaces in such telescopes must be manufactured to unimaginable standards of perfection of a few thousandths of a centimeter. The detection of imperfections of less than 1/20 of a wavelength of light, for application in the building of the mirror for the Space Infrared Telescope Facility, was undertaken. Because the mirror must be kept very cold while in space, another factor comes into effect: cryogenics. The process to test a specific morror under cryogenic conditions is described; including the follow-up analysis accomplished through computer work. To better illustrate the process and analysis, a Pyrex Hex-Core mirror is followed through the process from the laser interferometry in the lab, to computer analysis via a computer program called FRINGE. This analysis via FRINGE is detailed.

  13. Transition Metal Switchable Mirror

    SciTech Connect

    2009-01-01

    The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft. More information at: http://windows.lbl.gov/materials/chromogenics/default.htm

  14. Transition Metal Switchable Mirror

    ScienceCinema

    None

    2010-01-08

    The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft.

  15. Transition Metal Switchable Mirror

    ScienceCinema

    None

    2013-05-29

    The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft. More information at: http://windows.lbl.gov/materials/chromogenics/default.htm

  16. Mirror Measurement Device

    NASA Technical Reports Server (NTRS)

    1992-01-01

    A Small Business Innovation Research (SBIR) contract led to a commercially available instrument used to measure the shape profile of mirror surfaces in scientific instruments. Bauer Associates, Inc.'s Bauer Model 200 Profilometer is based upon a different measurement concept. The local curvature of the mirror's surface is measured at many points, and the collection of data is computer processed to yield the desired shape profile. (Earlier profilometers are based on the principle of interferometry.) The system is accurate and immune to problems like vibration and turbulence. Two profilometers are currently marketed, and a third will soon be commercialized.

  17. Flat Focusing Mirror

    PubMed Central

    Cheng, Y. C.; Kicas, S.; Trull, J.; Peckus, M.; Cojocaru, C.; Vilaseca, R.; Drazdys, R.; Staliunas, K.

    2014-01-01

    The control of spatial propagation properties of narrow light beams such as divergence, focusing or imaging are main objectives in optics and photonics. In this letter, we propose and demonstrate experimentally a flat focusing mirror, based on an especially designed dielectric structure without any optical axis. More generally, it also enables imaging any light pattern in reflection. The flat focusing mirror with a transversal invariance can largely increase the applicability of structured photonic materials for light beam propagation control in small-dimension photonic circuits. PMID:25228358

  18. Flat focusing mirror.

    PubMed

    Cheng, Y C; Kicas, S; Trull, J; Peckus, M; Cojocaru, C; Vilaseca, R; Drazdys, R; Staliunas, K

    2014-01-01

    The control of spatial propagation properties of narrow light beams such as divergence, focusing or imaging are main objectives in optics and photonics. In this letter, we propose and demonstrate experimentally a flat focusing mirror, based on an especially designed dielectric structure without any optical axis. More generally, it also enables imaging any light pattern in reflection. The flat focusing mirror with a transversal invariance can largely increase the applicability of structured photonic materials for light beam propagation control in small-dimension photonic circuits. PMID:25228358

  19. Transition Metal Switchable Mirror

    SciTech Connect

    2009-08-21

    The switchable-mirrors technology was developed by Tom Richardson and Jonathan Slack of Berkeley Lab's Environmental Energy Technologies Division. By using transition metals rather than the rare earth metals used in the first metal-hydride switchable mirrors, Richardson and Slack were able to lower the cost and simplify the manufacturing process. Energy performance is improved as well, because the new windows can reflect or transmit both visible and infrared light. Besides windows for offices and homes, possible applications include automobile sunroofs, signs and displays, aircraft windows, and spacecraft.

  20. Applications of MEMS in segmented mirror space telescopes

    NASA Astrophysics Data System (ADS)

    Agrawal, Brij; Kubby, Joel

    2011-03-01

    Development of space telescopes, such as the Hubble Space Telescope and the James Webb Telescope has been very challenging in terms of cost, schedule, and performance. For several future space missions, larger aperture and lightweight deployable mirrors, in the range of 10-20 meters in diameter with high surface accuracy, are required. In order to achieve lightweight, reduce cost for development and provide performance robustness, actuated hybrid mirror (AHM) technology is under development. The Naval Postgraduate School (NPS) recently received a 3-meter diameter space telescope testbed with six segments that uses an AHM technology. This paper will discuss the work performed at NPS on the surface control of the primary mirror using adaptive optics. This paper will also discuss how we can use a MEMS deformable mirror to improve the performance of the NPS segmented mirror telescope. The high-stroke, high-order actuated MEMS deformable mirror will correct the residual alignment and surface errors that are not corrected by the actuators on the mirrors. The mirror will use electrostatic actuation to eliminate the need for power to hold its position and will be capable of open-loop, go-to positioning.

  1. Secondary osteon size and collagen/lamellar organization ("osteon morphotypes") are not coupled, but potentially adapt independently for local strain mode or magnitude.

    PubMed

    Skedros, John G; Keenan, Kendra E; Williams, Tyler J; Kiser, Casey J

    2013-02-01

    In bone, matrix slippage that occurs at cement lines of secondary osteons during loading is an important toughening mechanism. Toughness can also be enhanced by modifications in osteon cross-sectional size (diameter) for specific load environments; for example, smaller osteons in more highly strained "compression" regions vs. larger osteons in less strained "tension" regions. Additional osteon characteristics that enhance toughness are distinctive variations in collagen/lamellar organization (i.e., "osteon morphotypes"). Interactions might exist between osteon diameter and morphotype that represent adaptations for resisting deleterious shear stresses that occur at the cement line. This may be why osteons often have a peripheral ring (or "hoop") of highly oblique/transverse collagen. We hypothesized that well developed/distinct "hoops" are compensatory adaptations in cases where increased osteon diameter is mechanically advantageous (e.g., larger osteons in "tension" regions would have well developed/distinct "hoops" in order to resist deleterious consequences of co-existing localized shear stresses). We tested this hypothesis by determining if there are correlations between osteon diameters and strongly hooped morphotypes in "tension", "compression", and "neutral axis" regions of femora (chimpanzees, humans), radii (horse, sheep) and calcanei (horse, deer). The results reject the hypothesis-larger osteons are not associated with well developed/distinct "hoops", even in "tension regions" where the effect was expected to be obvious. Although osteon diameter and morphotype are not coupled, osteon diameters seem to be associated with increased strain magnitudes in some cases, but this is inconsistent. By contrast, osteon morphotypes are more strongly correlated with the distribution of tension and compression. PMID:23123271

  2. Paranal Receives New Mirror

    NASA Astrophysics Data System (ADS)

    2008-04-01

    A 4.1-metre diameter primary mirror, a vital part of the world's newest and fastest survey telescope, VISTA (the Visible and Infrared Survey Telescope for Astronomy) has been delivered to its new mountaintop home at Cerro Paranal, Chile. The mirror will now be coupled with a small camera for initial testing prior to installing the main camera in June. Full scientific operations are due to start early next year. VISTA will form part of ESO's Very Large Telescope facility. ESO PR Photo 10d/08 ESO PR Photo 10d/08 The VISTA Mirror The mirror arrived over the Easter weekend at the Paranal Observatory where the telescope is being assembled at an altitude of 2518m, in Chile's Atacama Desert. VISTA Project Manager Alistair McPherson from STFC's UK Astronomy Technology Centre (UK ATC) accompanied the mirror on its journey to Chile: "This is a major milestone for the VISTA project. The precious mirror was loaded on to a plane in a special cradle that used tennis balls to cushion it from impact for its arduous journey across three continents. " "The mirror had a difficult four-day journey, by air and by road. It arrived in perfect condition and now that it has been coated, we will install the mirror in the telescope with a small test camera for about four weeks testing. We plan to install the main camera in June," said the Project Scientist on VISTA, Will Sutherland of Queen Mary, University of London, UK. The VISTA 4.1-metre diameter primary mirror is the most strongly curved large mirror ever polished to such a precise and exacting surface accuracy - deviations from a perfect surface of less than 1/3000th of the thickness of a human hair. On arrival at Cerro Paranal it was safely craned into the telescope dome where it was washed and coated with a thin layer of protected silver in the facility's coating plant. Silver is the best metal for the purpose since it reflects over 98% of near-infrared light, better than the more commonly used aluminium. To date, the reflectivity

  3. Large Telescope Segmented Primary Mirror Alignment

    NASA Technical Reports Server (NTRS)

    Rud, Mayer

    2010-01-01

    A document discusses a broadband (white light) point source, located at the telescope Cassegrain focus, which generates a cone of light limited by the hole in the secondary mirror (SM). It propagates to the aspheric null-mirror, which is optimized to make all the reflected rays to be normal to the primary mirror (PM) upon reflection. PM retro-reflects the rays back through the system for wavefront analysis. The point source and the wavefront analysis subsystems are all located behind the PM. The PM phasing is absolute (white light) and does not involve the SM. A relatively small, aspheric null-mirror located near the PM center of curvature has been designed to deliver the high level of optical wavefront correction. The phasing of the segments is absolute due to the use of a broadband source. The segmented PM is optically aligned independently and separately from the SM alignment. The separation of the PM segments alignment from the PM to the SM, and other telescope optics alignments, may be a significant advantage, eliminating the errors coupling. The point source of this concept is fully cooperative, unlike a star or laser-generated guide-star, providing the necessary brightness for the optimal S/N ratio, the spectral content, and the stable on-axis position. This concept can be implemented in the lab for the PM initial alignment, or made to be a permanent feature of the space-based or groundbased telescope.

  4. The effect of a locally adapted, secondary stroke risk factor self-management program on medication adherence among veterans with stroke/TIA.

    PubMed

    Damush, Teresa M; Myers, Laura; Anderson, Jane A; Yu, Zhangsheng; Ofner, Susan; Nicholas, Gloria; Kimmel, Barbara; Schmid, Arlene A; Kent, Thomas; Williams, Linda S

    2016-09-01

    We targeted stroke/transient ischemic attack (TIA) survivors to engage in self-management practices to manage secondary stroke risk factors. We conducted a randomized, regional pilot trial of a locally adapted, secondary stroke prevention program. We implemented the program at two Veterans Administration Medical Centers. Program sessions targeted stroke risk factor self-management. Specifically, we evaluated the effect of the program on the reach, implementation, and effectiveness on patient self-efficacy; stroke-specific, health-related quality of life; and medication adherence for the prevalent stroke risk factors: (1) diabetes, (2) hypertension, and (3) hyperlipidemia. Medication possession ratios were calculated to evaluate medication adherence using VA pharmacy benefits data pre (6 months prior) and post (6 months after) the stroke/TIA event. Based upon the literature standard of 80 % compliance rate, we dichotomized compliance and modeled the data using logistical regression. Final sample included 174 veterans with an acute stroke or TIA who were randomized to receive either the intervention (n = 87) or attention control program (n = 87). Patient self-efficacy and stroke-specific, health-related quality of life at 6 months did not significantly differ between groups. We found improvements in medication adherence within the intervention group. In the intervention group, the odds of compliance with diabetes medications post-stroke were significantly larger than the odds of compliance prior to the stroke (odds ratio = 3.45 (95 % CI = 1.08-10.96). For compliance to hypertension medications, the intervention group showed significantly greater odds of compliance post intervention than pre intervention (odds ratio = 3. 68 (95 % CI = 1.81-7.48). The control group showed no difference in compliance rates from baseline to follow-up. For adherence to hypercholesterolemia medications, both the intervention (odds ratio = 5.98 (95 % CI

  5. JWST Mirror Technology Development

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip

    2010-01-01

    Since the initial Design Studies leading to JWST, Mirror Technology was identified as a (if not the) critical capability necessary to enable the next generation of large aperture space telescopes required to achieve the science goals of imaging the earliest galaxies and proto-galaxies after the big bang. Specific telescope architectures were explored via three independent design concept studies conducted during the summer of 1996. Achieving the desired science objectives required a never before demonstrated space telescope capability, one with an 8 meter class primary mirror that is diffraction limited at 2 micrometers and operating in deep space at temperatures well below 70K. Beryllium was identified in the NASA "Yardstick" design as the preferred material because of its ability to provide stable optical performance in the anticipated thermal environment as well as its excellent specific stiffness. Because of launch vehicle constraints, two very significant architectural constraints were placed upon the telescope: segmentation and areal density. Each of these directly resulted in specific technology capability requirements. First, because the maximum launch vehicle payload fairing diameter is approximately 4.5 meters, the only way to launch an 8 meter class mirror is to segment it, fold it and deploy it on orbit - resulting in actuation and control requirements. Second, because of launch vehicle mass limits, the primary mirror allocation was only 1000 kg - resulting in a maximum areal density specification of 20 kilograms per square meter.

  6. Tandem mirror fusion research

    SciTech Connect

    Baldwin, D.E.

    1983-12-02

    The tandem mirror program has evolved considerably in the last decade. Of significance is the viable reactor concept embodied in the MARS design. An aggressive experimental program, culminating in the operation of MFTF-B in late 1986, will provide a firm basis for refining the MARS design as necessary for constructing a reactor prototype in the 1990s.

  7. Rearview Mirror Dimming Function

    ERIC Educational Resources Information Center

    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.

  8. Durable metallized polymer mirror

    DOEpatents

    Schissel, Paul O.; Kennedy, Cheryl E.; Jorgensen, Gary J.; Shinton, Yvonne D.; Goggin, Rita M.

    1994-01-01

    A metallized polymer mirror construction having improved durability against delamination and tunneling, comprising: an outer layer of polymeric material; a metal oxide layer underlying the outer layer of polymeric material; a silver reflective layer underneath the metal oxide layer; and a layer of adhesive attaching the silver layer to a substrate.

  9. Durable metallized polymer mirror

    DOEpatents

    Schissel, P.O.; Kennedy, C.E.; Jorgensen, G.J.; Shinton, Y.D.; Goggin, R.M.

    1994-11-01

    A metallized polymer mirror construction is disclosed having improved durability against delamination and tunneling, comprising: an outer layer of polymeric material; a metal oxide layer underlying the outer layer of polymeric material; a silver reflective layer underneath the metal oxide layer; and a layer of adhesive attaching the silver layer to a substrate. 6 figs.

  10. Cosmology with liquid mirror telescopes

    NASA Technical Reports Server (NTRS)

    Hogg, David W.; Gibson, Brad K.; Hickson, Paul

    1993-01-01

    Liquid mirrors provide an exciting means to obtain large optical telescopes for substantially lower costs than conventional technologies. The liquid mirror concept has been demonstrated in the lab with the construction of a diffraction limited 1.5 m mirror. The mirror surface, using liquid mercury, forms a perfect parabolic shape when the mirror cell is rotated at a uniform velocity. A liquid mirror must be able to support a heavy mercury load with minimal flexure and have a fundamental resonant frequency that is as high as possible, to suppress the amplitude of surface waves caused by small vibrations transmitted to the mirror. To minimize the transmission of vibrations to the liquid surface, the entire mirror rests on an air bearing. This necessitates the mirror cell being lightweight, due to the limited load capabilities of the air bearing. The mirror components must also have physical characteristics which minimize the effects of thermal expansion with ambient temperature fluctuations in the observatory. In addition, the 2.7 m mirror construction is designed so that the techniques used may be readily extended to the construction of large mirrors. To attain the goals of a lightweight, rigid mirror, a composite laminant construction was used. The mirror consists of a foam core cut to the desired parabolic shape, with an accuracy of a few mm. An aluminum hub serves as an anchor for the foam and skin, and allows precise centering of the mirror on the air bearing and drive system. Several plys of Kevlar, covered in an epoxy matrix, are then applied to the foam. A final layer of pure epoxy is formed by spin casting. This final layer is parabolic to within a fraction of a mm. An aluminum ring bonded to the circumference of the mirror retains the mercury, and incorporates stainless-steel hard-points for the attachment of balance weights.

  11. Individual differences in perceptual adaptability of foreign sound categories.

    PubMed

    Schertz, Jessamyn; Cho, Taehong; Lotto, Andrew; Warner, Natasha

    2016-01-01

    Listeners possess a remarkable ability to adapt to acoustic variability in the realization of speech sound categories (e.g., different accents). The current work tests whether non-native listeners adapt their use of acoustic cues in phonetic categorization when they are confronted with changes in the distribution of cues in the input, as native listeners do, and examines to what extent these adaptation patterns are influenced by individual cue-weighting strategies. In line with previous work, native English listeners, who use voice onset time (VOT) as a primary cue to the stop voicing contrast (e.g., 'pa' vs. 'ba'), adjusted their use of f0 (a secondary cue to the contrast) when confronted with a noncanonical "accent" in which the two cues gave conflicting information about category membership. Native Korean listeners' adaptation strategies, while variable, were predictable based on their initial cue weighting strategies. In particular, listeners who used f0 as the primary cue to category membership adjusted their use of VOT (their secondary cue) in response to the noncanonical accent, mirroring the native pattern of "downweighting" a secondary cue. Results suggest that non-native listeners show native-like sensitivity to distributional information in the input and use this information to adjust categorization, just as native listeners do, with the specific trajectory of category adaptation governed by initial cue-weighting strategies. PMID:26404530

  12. Long Focal Length Large Mirror Fabrication System

    NASA Technical Reports Server (NTRS)

    Bennett, H. E.

    2003-01-01

    The goals of this ambitious program are (1) to develop systems to make large superpolished optical mirrors, (2) to develop low scatter polishing techniques using centrifugal elutriation, (3) to develop a means of measuring scatter at any point on the mirror, (4) to polish a Hindle sphere to measure the optical figure of a one meter diameter convex mandrel, and (5) to fabricate low scatter, large adaptive optic graphite filled, cyanate ester replica transfer mirrors using these mandrels. Deliverables are a 30 cm diameter superpolished composite AO mirror. We fabricated a 1/3rd meter superpolished zerodur flat mandrel and with the support of our major subcontractor, Composite Mirror Applications Inc (CMA) we have demonstrated a 30 cm lightweight cyanate ester mirror with an rms microroughness between 0.6 and 0.8 nm and 8 faceplate influence function of 5 cm. The influence function was chosen to be comparable to the atmospheric correlation coefficient r(sub 0) which is about 5 cm at sea level. There was no print-thru of the graphite fibers in the cyanate ester surface (the bane of many previous efforts to use cyanate ester mirrors). Our subcontractor has devised a means for developing a 30-50 nm thick layer of graphite free pure ester resin on the surface of the mirrors. This graphite fiber filled material has a thermal expansion coefficient in the 10(exp -8) centimeter per Kelvin range (the same range of expansion coefficient as Zerodur and ULE glasses) and does not take up water and swell, so it is a nearly ideal mirror material in these areas. Unfortunately for these 0.8mm thick faceplates, the number of plies is not enough to result in isometric coverage. Isolated figure irregularities can appear, making it necessary to go to thicker faceplates. The influence function will then only approximate the length of r(sub 0), at higher altitudes or longer wavelengths. The influence function goes as the cube of the thickness, so we are now making a faceplate optimized for

  13. Deployable telescope having a thin-film mirror and metering structure

    DOEpatents

    Krumel, Leslie J.; Martin, Jeffrey W.

    2010-08-24

    A deployable thin-film mirror telescope comprises a base structure and a metering structure. The base structure houses a thin-film mirror, which can be rolled for stowage and unrolled for deployment. The metering structure is coupled to the base structure and can be folded for stowage and unfolded for deployment. In the deployed state, the unrolled thin-film mirror forms a primary minor for the telescope and the unfolded metering structure positions a secondary minor for the telescope.

  14. White-Light Phase-Conjugate Mirrors as Distortion Correctors

    NASA Technical Reports Server (NTRS)

    Frazier, Donald; Smith, W. Scott; Abdeldayem, Hossin; Banerjee, Partha

    2010-01-01

    White-light phase-conjugate mirrors would be incorporated into some optical systems, according to a proposal, as means of correcting for wavefront distortions caused by imperfections in large optical components. The proposal was given impetus by a recent demonstration that white, incoherent light can be made to undergo phase conjugation, whereas previously, only coherent light was known to undergo phase conjugation. This proposal, which is potentially applicable to almost any optical system, was motivated by a need to correct optical aberrations of the primary mirror of the Hubble Space telescope. It is difficult to fabricate large optical components like the Hubble primary mirror and to ensure the high precision typically required of such components. In most cases, despite best efforts, the components as fabricated have small imperfections that introduce optical aberrations that adversely affect imaging quality. Correcting for such aberrations is difficult and costly. The proposed use of white-light phase conjugate mirrors offers a relatively simple and inexpensive solution of the aberration-correction problem. Indeed, it should be possible to simplify the entire approach to making large optical components because there would be no need to fabricate those components with extremely high precision in the first place: A white-light phase-conjugate mirror could correct for all the distortions and aberrations in an optical system. The use of white-light phase-conjugate mirrors would be essential for ensuring high performance in optical systems containing lightweight membrane mirrors, which are highly deformable. As used here, "phase-conjugate mirror" signifies, more specifically, an optical component in which incident light undergoes time-reversal phase conjugation. In practice, a phase-conjugate mirror would typically be implemented by use of a suitably positioned and oriented photorefractive crystal. In the case of a telescope comprising a primary and secondary

  15. Development of SiC Mirror for ASTRO-F

    NASA Astrophysics Data System (ADS)

    Kaneda, H.; Onaka, T.; Yamashiro, R.

    2000-12-01

    The development of the light-weight silicon carbide mirrors for the ASTRO-F mission is described in this paper. These mirrors are made of a sandwich-type SiC material, consisting of light porous core and dense CVD (chemical vapor deposition) coat of SiC. The primary mirror has a diameter of 710 mm and weighs only 11 kg. Combined with the secondary mirror of the same type, they form Ritchey-Chretien type telescope (F/6), which is cooled down to 5.8 K. Fabrication of the small-scale test SiC mirror has been successful which shows very little deformation of the figure at liquid-helium temperatures. Another type of the SiC coated mirror has been tested which has the same size as flight model, but of which core is made of graphite. At present, polishing of the flight-model primary mirror is going on. Construction of the flight model telescope system will be finished in 2001.

  16. Prototype Development of the GMT Fast Steering Mirror

    NASA Astrophysics Data System (ADS)

    Kim, Young-Soo; Koh, J.; Jung, H.; Jung, H.; Cho, M. K.; Park, W.; Yang, H.; Kim, H.; Lee, K.; Ahn, H.; Park, B.

    2013-06-01

    A Fast Steering Mirror (FSM) is going to be produced as a secondary mirror of the Giant Magellan Telescope (GMT). FSM is 3.2 m in diameter and the focal ratio is 0.65. It is composed of seven circular segments which match with the primary mirror segments. Each segment contains a light-weighted mirror whose diameter is 1.1 m. It also contains tip-tilt actuators which would compensate wind effect and structure jitter. An FSM prototype (FSMP) has been developed, which consists of a full-size off-axis mirror segment and a tip-tilt test-bed. The main purpose of the FSMP development is to achieve key technologies, such as fabrication of highly aspheric off-axis mirror and tip-tilt actuation. The development has been conducted by a consortium of five institutions in Korea and USA, and led by Korea Astronomy and Space Science Institute. The mirror was light-weighted and grinding of the front surface was finished. Polishing is in progress with computer generated hologram tests. The tip-tilt test-bed has been manufactured and assembled. Frequency tests are being performed and optical tilt set-up is arranged for visual demonstration. In this paper, we present progress of the prototype development, and future works.

  17. A Novel Effect of Scattered-Light Interference in Misted Mirrors

    ERIC Educational Resources Information Center

    Bridge, N. James

    2005-01-01

    Interference rings can be observed in mirrors clouded by condensation, even in diffuse lighting. The effect depends on individual droplets acting as point sources by refracting light into the mirror, so producing coherent wave-trains which are reflected and then scattered again by diffraction round the same source droplet. The secondary wave-train…

  18. Congenital mirror movements.

    PubMed Central

    Schott, G D; Wyke, M A

    1981-01-01

    In this report are described seven patients assessed clinically and neuropsychologically in whom mirror movements affecting predominantly the hands occurred as a congenital disorder. These mirror movements, representing a specific type of abnormal synkinesia, may arise as a hereditary condition, in the presence of a recognisable underlying neurological abnormality, and sporadically, and the seven patients provide more or less satisfactory examples of each of these three groups. Despite the apparent uniformity of the disorder, the heterogeneity and variability may be marked, examples in some of our patients including the pronounced increase in tone that developed with arm movement, and the capacity for modulation of the associated movement by alteration of neck position and bio-feedback. Various possible mechanisms are considered; these include impaired cerebral inhibition of unwanted movements, and functioning of abnormal motor pathways. Emphasis has been placed on the putative role of the direct, crossed corticomotoneurone pathways and on the unilateral and bilateral cerebral events that precede movement. PMID:7288446

  19. Dynamic coherent backscattering mirror

    PubMed Central

    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

  20. Dynamic coherent backscattering mirror

    NASA Astrophysics Data System (ADS)

    Zeylikovich, I.; Xu, M.

    2016-02-01

    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.

  1. Complex/Symplectic Mirrors

    SciTech Connect

    Chuang, Wu-yen; Kachru, Shamit; 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.

  2. Lightweight Substrates For Mirrors

    NASA Technical Reports Server (NTRS)

    Brown, D. Kyle

    1991-01-01

    New substrate uses conventional quasi-isotropic fabric laminate with surfacing layer of carbon-fiber paper consisting of randomly oriented chopped carbon fibers. Layered structure of fabric and paper relatively easy to manufacture. When impregnated with carbon, structure rigid and stable. Substrates of this type made quite thin, thus keeping areal weights to minimum. Mirrors of this type made faster, and cost less, than predecessors.

  3. Joined Beryllium Mirror Demonstrator

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip; Parsonage, Tom; Burdine, Robert (Technical Monitor)

    2001-01-01

    Fabrications of large Beryllium optical components are fundamentally limited by available facility capabilities. To overcome this limitation, NASA funded Brush Wellman Corp to study a Be joining process. Four 76 mm diameters samples and a 0.5 mm diameter Joined Beryllium Mirror Demonstrator (JBMD) were fabricated. This presentation will review the fabrication of these samples and summarize the results of their cryogenic testing at MSFCs XRCF.

  4. Replication of lightweight mirrors

    NASA Astrophysics Data System (ADS)

    Chen, Ming Y.; Matson, Lawrence E.; Lee, Heedong; Chen, Chenggang

    2009-08-01

    The fabrication of lightweight mirror assemblages via a replication technique offers great potential for eliminating the high cost and schedule associated with the grinding and polishing steps needed for conventional glass or SiC mirrors. A replication mandrel is polished to an inverse figure shape and to the desired finish quality. It is then, coated with a release layer, the appropriate reflective layer, and followed by a laminate for coefficient of thermal expansion (CTE) tailorability and strength. This optical membrane is adhered to a mirror structural substrate with a low shrinkage, CTE tailored adhesive. Afterwards, the whole assembly is separated from the mandrel. The mandrel is then cleaned and reused for the next replication run. The ultimate goal of replication is to preserve the surface finish and figure of the optical membrane upon its release from the mandrel. Successful replication requires a minimization of the residual stresses within the optical coating stack, the curing stresses from the adhesive and the thermal stress resulting from CTE mismatch between the structural substrate, the adhesive, and the optical membrane. In this paper, the results on replicated trials using both metal/metal and ceramic/ceramic laminates adhered to light weighted structural substrates made from syntactic foams (both inorganic and organic) will be discussed.

  5. Strehl Ratio Meter for Focusing Segmented Mirrors 1

    NASA Technical Reports Server (NTRS)

    Olivier, Philip D.

    1996-01-01

    Initial focusing segmented mirrors that must be deployed in space, such as the Next Generation Space Telescope (NGST), provide challenges not faced before in the area of adaptive optics. The devices used to focus the mirror must minimize the power used and unnecessary mechanical movement. The device described in this report requires no movable parts except for the essential actuators required to move the mirror segments. Detail description of the components can be found in Coker, 1996. The primary mirror of the NGST will consist of 9 segments, a central annular segment, surrounded by 8 segments. The entire mirror assembly will be an 8 meter nearly filled circle (with the corners of the segments clipped to allow for storage in an Atlas IIe shroud). As the segments of the primary mirror are deployed to their operational positions, they must be positioned to within small fractions of a wavelength of near infrared light. When focused, the NGST will put most of its collected li-ht into the small region near the center of its focal plane. The ratio of the total light in the diffraction limited spot about the center of the focal plane to the total light in the focal plane. The purpose of this research effort is to design and build a device that will measure Strehl ratio and to use demonstrate that the Strehl ratio can be used to focus a segmented mirror.

  6. Scan mirror remote temperature sensing system and method

    NASA Technical Reports Server (NTRS)

    VanDyk, Steven G. (Inventor); Balinski, Walter (Inventor); Choo, Ronald J. (Inventor); Bortfeldt, Paul E. (Inventor)

    2000-01-01

    A remote temperature sensing system (10) for a scanning mirror (7). The system (10) includes a sensor which detects heat radiated by the mirror and provides a signal in response thereto. In the illustrative implementation, the system (10) includes a thermistor mounted within a housing. The housing is contoured to maximize the receipt of thermal energy thereby. A mounting assembly maintains the thermistor a predetermined nonzero distance from the scanning mirror (7). The invention includes a shroud (12) mounted on the mirror (7) for shielding the thermistor and a support tube connected to the thermistor housing on a first end and to a base on the second end thereof. The support tube is adapted to remain stationary within the shroud as the scanning mirror and the shroud rotate due to the scanning of the mirror. Wires are connected to the thermistor on a first end thereof and are wrapped around the support tube. The wires include a length of electrically conductive material having a resistivity which has a low sensitivity to temperature variations. The sensor output is processed in a conventional manner to provide an output indicative of the temperature of the mirror.

  7. Actuation of Deformable Mirrors Using Laser Controlled Pistons

    NASA Technical Reports Server (NTRS)

    Scott, Charles E.

    2005-01-01

    Current deformable mirrors used for adaptive optics employ many actuators to adjust the mirror in order to compensate for optical irregularities. These mechanical actuators, which can number in the hundreds for a given mirror, require a significant amount of electrical wires in order to be controlled. The objective of this research is to implement a different type of actuator that can be controlled without the use of wires. The actuator developed employs a laser to quickly heat and expand the air in a closed "cell." When the air expands, it pushes a membrane that causes the mirror to move. Creating an array of these cells, and scanning them with a laser can control a deformable mirror. Testing showed that a single cell with a 5-mm diameter and 10-mm length can deflect a membrane of aluminized mylar in excess of our minimum requirement of 20 microns. These cells can now be assembled in a 5x5 matrix and attached to many small Mirrors. An electro-mechanical scanning assembly can be used to aim the laser directly onto individual cells causing the mirror at that location to move.

  8. Actuation of Deformable Mirrors Using Laser Controlled Pistons

    NASA Technical Reports Server (NTRS)

    Scott, Charles

    2005-01-01

    Current deformable mirrors used for adaptive optics employ many actuators to adjust the mirror in order to compensate for optical irregularities. These mechanical actuators, which can number in the hundreds for a given mirror, require a significant amount of electrical wires in order to be controlled. The objective of this research is to implement a different type of actuator that can be controlled without the use of wires. The actuator developed employs a laser to quickly heat and expand the air in a closed 'cell'. When the air expands, it pushes a membrane that causes the mirror to move. Creating an array of these cells, and scanning them with a laser can control a deformable mirror. Testing showed that a single cell with a 5 mm diameter and 10 mm in length can deflect a membrane of aluminized Mylar in excess of our minimum requirement of 20 microns. These cells can now be assembled in a 5 x 5 matrix and attached to many small mirrors. An electro-mechanical scanning assembly can be used to aim the laser directly onto individual cells causing the mirror at that location to move.

  9. Progress in the Fabrication and Testing of Telescope Mirrors for The James Webb Space Telescope

    NASA Astrophysics Data System (ADS)

    Bowers, Charles W.; Clampin, M.; Feinberg, L.; Keski-Kuha, R.; McKay, A.; Chaney, D.; Gallagher, B.; Ha, K.

    2012-01-01

    The telescope of the James Webb Space Telescope (JWST) is an f/20, three mirror anastigmat design, passively cooled (40K) in an L2 orbit. The design provides diffraction limited performance (Strehl ≥ 0.8) at λ=2μm. To fit within the launch vehicle envelope (Arianne V), the 6.6 meter primary mirror and the secondary mirror support structure are folded for launch, then deployed and aligned in space. The primary mirror is composed of 18 individual, 1.3 meter (flat:flat) hexagonal segments, each adjustable in seven degrees of freedom (six rigid body + radius of curvature) provided by a set of high precision actuators. The actuated secondary mirror ( 0.74m) is similarly positioned in six degrees of rigid body motion. The .70x.51m, fixed tertiary and 0.17m, flat fine steering mirror complete the telescope mirror complement. The telescope is supported by a composite structure optimized for performance at cryogenic temperatures. All telescope mirrors are made of Be with substantial lightweighting (21kg for each 1.3M primary segment). Additional Be mounting and supporting structure for the high precision ( 10nm steps) actuators are attached to the primary segments and secondary mirror. All mirrors undergo a process of thermal stabilization to reduce stress. An extensive series of interferometric measurements guide each step of the polishing process. Final polishing must account for any deformation between the ambient temperature of polishing and the cryogenic, operational temperature. This is accomplished by producing highly precise, cryo deformation target maps of each surface which are incorporated into the final polishing cycle. All flight mirrors have now completed polishing, coating with protected Au and final cryo testing, and the telescope is on track to meet all system requirements. We here review the measured performance of the component mirrors and the predicted performance of the flight telescope.

  10. A spectrum of shadowed mirroring.

    PubMed

    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. PMID:22489812

  11. Effects of a realistic adaptive optics system on the atmospheric propagation of a high energy laser beam

    NASA Astrophysics Data System (ADS)

    Digumarthi, Ramji V.; Mehta, Naresh C.; Blankinship, Ross M.

    1990-05-01

    An adaptive optics (AO) correction system is generally required to compensate for beam degradations caused by interactions between a high energy laser (HEL) beam and the atmosphere. The GRAND propagation code includes a model of a realistic AO system representing many features of a state-of-the-art beam control system. This AO system includes models of a wavefront sensor, a tilt mirror, a focus (secondary) mirror, and a woofer-tweeter deformable mirror arrangement. This paper reports the results of a study to assess the impact of the realistic AO system on the correctability of HEL-atmosphere interactions. The GRAND code results compare the performance of the low-pass filter model and the realistic AO system model in the presence of turbulence and moderate-to-severe thermal blooming. In addition, the effects of low frequency Kolmogorov turbulence were studied in terms of its impact on the AO system requirements.

  12. NFIRAOS: TMT facility adaptive optics with conventional DMs

    NASA Astrophysics Data System (ADS)

    Herriot, Glen; Hickson, Paul; Ellerbroek, B. L.; Andersen, David A.; Davidge, T.; Erickson, D. A.; Powell, I. P.; Clare, R.; Smith, M.; Saddlemyer, L.; Veran, J.-P.

    2005-08-01

    Although many of the instruments planned for the TMT (Thirty Meter Telescope) have their own closely-coupled adaptive optics systems, TMT will also have a facility Adaptive Optics (AO) system feeding three instruments on the Nasmyth platform. For this Narrow-Field Infrared Adaptive Optics System, NFIRAOS (pronounced nefarious), the TMT project considered two architectures. One, described in this paper, employs conventional deformable mirrors with large diameters of about 300 mm and this is the reference design adopted by the TMT project. An alternative design based on MEMS was also studied, and is being presented separately in this conference. The requirements for NFIRAOS include 0.8-5 microns wavelength range, 30 arcsecond diameter output field of view (FOV), excellent sky coverage, and diffraction- limited atmospheric turbulence compensation (specified at 133 nm RMS including residual telescope and science instrument errors.) The reference design for NFIRAOS includes multiple sodium laser guide stars over a 70 arcsecond FOV, and an infrared tip/tilt/focus/astigmatism natural guide star sensor within instruments. Larger telescopes require greater deformable mirror (DM) stroke. Although initially NFIRAOS will correct a 10 arcsecond science field, it uses two deformable mirrors in series, partly to provide sufficient stroke for atmospheric correction over the 30 m telescope aperture, but mainly to partially correct a 2 arcminute diameter "technical" field to sharpen near-IR natural guide stars and improve sky coverage. The planned upgrade to full performance includes replacing the groundconjugated DM with a higher actuator density, and using a deformable telescope secondary mirror as a "woofer." NFIRAOS incorporates an instrument rotator and selection of three live instruments: a near-Infrared integral field Imaging spectrograph, a near-infrared echelle spectrograph, and after upgrading NFIRAOS to full multi-conjugation, a wide field (30 arcsecond) infrared camera.

  13. JWST Mirror Technology Development Results

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip

    2007-01-01

    Mirror technology is a critical enabling capability for the James Webb Space Telescope (JWST). JWST requires a Primary Mirror Segment Assembly (PMSA) that can survive launch, deploy and align itself to form a 25 square meter collecting area 6.5 meter diameter primary mirror with a 131 nm rms wavefront error at temperatures less than 50K and provide stable optical performance. At the inception of JWST in 1996, such a capability did not exist. A highly successful technology development program was initiated including the Sub-scale Beryllium Mirror Demonstrator (SBMD) and Advanced Mirror System Demonstrator (AMSD) projects. These projects along with flight program activities have matured and demonstrated mirror technology for JWST. Directly traceable prototypes or flight hardware has been built, tested and operated in a relevant environment. This paper summarizes that technology development effort.

  14. Variable focal length deformable mirror

    DOEpatents

    Headley, Daniel; Ramsey, Marc; Schwarz, Jens

    2007-06-12

    A variable focal length deformable mirror has an inner ring and an outer ring that simply support and push axially on opposite sides of a mirror plate. The resulting variable clamping force deforms the mirror plate to provide a parabolic mirror shape. The rings are parallel planar sections of a single paraboloid and can provide an on-axis focus, if the rings are circular, or an off-axis focus, if the rings are elliptical. The focal length of the deformable mirror can be varied by changing the variable clamping force. The deformable mirror can generally be used in any application requiring the focusing or defocusing of light, including with both coherent and incoherent light sources.

  15. Advanced Adaptive Optics Technology Development

    SciTech Connect

    Olivier, S

    2001-09-18

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

  16. SXI prototype mirror mount

    NASA Astrophysics Data System (ADS)

    1995-04-01

    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. A number of development hardware parts have been designed and fabricated jointly by MSFC and UAH for the engineering model of SXI. The major parts include a nickel electroformed mirror and a mirror mount, plating and coating of the ceramic spacers, and gold plating of the contact rings and fingers for the camera assembly. An aluminum model of the high accuracy sun sensor (HASS) was also designed and fabricated. A number of fiber optic tapers for the camera assembly were also coated with indium tin oxide and phosphor for testing and evaluation by MSFC. A large number of the SXI optical bench parts were also redesigned and simplified for a prototype telescope. These parts include the forward and rear support flanges, front aperture plate, the graphite epoxy optical bench and a test fixture for the prototype telescope. More than fifty (50) drawings were generated for various components of the prototype telescope. Some of these parts were subsequently fabricated at UAH machine shop or at MSFC or by the outside contractors. UAH also provide technical support to MSFC staff for a number of preliminary and critical design reviews. These design reviews included PDR and CDR for the mirror assembly by United Technologies Optical Systems (UTOS), and the program quarterly reviews, and SXI PDR and CDR. UAH staff also regularly attended the monthly status reviews, and made a significant number of suggestions to improve

  17. SXI Prototype mirror mount

    NASA Technical Reports Server (NTRS)

    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.

  18. SXI prototype mirror mount

    NASA Technical Reports Server (NTRS)

    1995-01-01

    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. A number of development hardware parts have been designed and fabricated jointly by MSFC and UAH for the engineering model of SXI. The major parts include a nickel electroformed mirror and a mirror mount, plating and coating of the ceramic spacers, and gold plating of the contact rings and fingers for the camera assembly. An aluminum model of the high accuracy sun sensor (HASS) was also designed and fabricated. A number of fiber optic tapers for the camera assembly were also coated with indium tin oxide and phosphor for testing and evaluation by MSFC. A large number of the SXI optical bench parts were also redesigned and simplified for a prototype telescope. These parts include the forward and rear support flanges, front aperture plate, the graphite epoxy optical bench and a test fixture for the prototype telescope. More than fifty (50) drawings were generated for various components of the prototype telescope. Some of these parts were subsequently fabricated at UAH machine shop or at MSFC or by the outside contractors. UAH also provide technical support to MSFC staff for a number of preliminary and critical design reviews. These design reviews included PDR and CDR for the mirror assembly by United Technologies Optical Systems (UTOS), and the program quarterly reviews, and SXI PDR and CDR. UAH staff also regularly attended the monthly status reviews, and made a significant number of suggestions to improve

  19. A mirror to analysis.

    PubMed

    Cohen, M

    2000-12-01

    Three books written by psychiatrists for a lay audience are examined. Two are novels, and the third is a psychiatrist's account of the years of his psychiatric residency training. In all three books psychoanalysts are portrayed in negative roles, as arrogant, cold, uncaring, and even venal. The reasons why psychiatrists would portray analysis in this light are examined, and some ways in which psychoanalysts will need to re-examine their role in education and in their relationships with psychiatric colleagues in order to counteract this negative "mirror" are suggested. PMID:11143896

  20. Poco Graphite Mirror Metrology Report

    NASA Technical Reports Server (NTRS)

    Kester, Thomas J.

    2005-01-01

    Recently a lightweight mirror technology was tested at Marshall Space Flight Center's Space Optic Manufacturing Technology Center (MSFC, SOMTC). The mirror is a Poco Graphite CVD Si clad SiC substrate. It was tested for cryogenic (cryo) survivability to 20deg Kelvin in SOMTC's X-ray Calibration and Cryogenic Test Facility. The surface figure of the mirror was measured before and after cry0 cycling. The test technique and results are discussed.

  1. Two mirror objective design for multispectral remote sensing

    NASA Technical Reports Server (NTRS)

    Clark, P. P.

    1982-01-01

    A two mirror flat field anastigmatic telescope was designed for multispectral sensing. The design was adapted to prism-type beamsplitting arrangements without loss of multispectral image quality by the addition of one refractive element. In addition to being relatively simple and mechanically insensitive, the design is immune to focus shift caused by index of refraction variation with temperature.

  2. Correction for thermal distortions of laser beams with a flexible mirror. Experimental and numerical investigations

    NASA Astrophysics Data System (ADS)

    Kanev, F.; Makenova, N.; Nesterov, R.; Izmailov, I.

    2016-04-01

    A mathematical model of an adaptive optics system was described in the article. The model included two main components: the model of an adaptive mirror and model of beam propagation under conditions of thermal blooming. Results of numerical simulation of adaptive optics systems were compared with data of laboratory experiments. High reliability of the model was shown.

  3. Scanning mirror for infrared sensors

    NASA Technical Reports Server (NTRS)

    Anderson, R. H.; Bernstein, S. B.

    1972-01-01

    A high resolution, long life angle-encoded scanning mirror, built for application in an infrared attitude sensor, is described. The mirror uses a Moire' fringe type optical encoder and unique torsion bar suspension together with a magnetic drive to meet stringent operational and environmental requirements at a minimum weight and with minimum power consumption. Details of the specifications, design, and construction are presented with an analysis of the mirror suspension that allows accurate prediction of performance. The emphasis is on mechanical design considerations, and brief discussions are included on the encoder and magnetic drive to provide a complete view of the mirror system and its capabilities.

  4. JWST Primary Mirror Technology Development

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip

    2010-01-01

    Mirror Technology was identified as a (if not the) critical capability necessary to achieve the Level 1 science goals. A never before demonstrated space telescope capability was required: 6 to 8 meter class pri mary mirror, diffraction limited at 2 micrometers and operates at temperatures below 50K. Launch vehicle constraints placed significant architectural constraints: deployed/segmented primary mirror (4.5 meter fairing diameter) 20 kg/m2 areal density (PM 1000 kg mass) Such mirror technology had never been demonstrated - and did not exist

  5. Gasdynamic Mirror Fusion Propulsion Experiment

    NASA Astrophysics Data System (ADS)

    Emrich, Bill

    2000-10-01

    A gasdynamic mirror (GDM) fusion propulsion experiment is currently being constructed at the NASA Marshall Space Flight Center (MSFC) to test the feasibility of this particular type of fusion device. Because of the open magnetic field line configuration of mirror fusion devices, they are particularly well suited for propulsion system applications since they allow for the easy ejection of thrust producing plasma. Currently, the MSFC GDM is constructed in three segments. The vacuum chamber mirror segment, the plasma injector mirror segment, and the main plasma chamber segment. Enough magnets are currently available to construct up to three main plasma chamber segments. The mirror segments are also segmented such that they can be expanded to accommodate new end plugging strategies without requiring the disassembly of the entire mirror segment. The plasma for the experiment is generated in a microwave cavity located between the main magnets and the mirror magnets. Ion heating is accomplished through ambipolar diffusion. The objective of the experiment is to investigate the stability characteristics of the gasdynamic mirror and to map a region of parameter space within which the plasma can be confined in a stable steady state configuration. The mirror ratio, plasma density, and plasma ``b" will be varied over a range of values and measurements subsequently taken to determine the degree of plasma stability.

  6. Gasdynamic Mirror Fusion Propulsion Experiment

    NASA Technical Reports Server (NTRS)

    Emrich, Bill; Rodgers, Stephen L. (Technical Monitor)

    2000-01-01

    A gasdynamic mirror (GDM) fusion propulsion experiment is currently being constructed at the NASA Marshall Space Flight Center (MSFC) to test the feasibility of this particular type of fusion device. Because of the open magnetic field line configuration of mirror fusion devices, they are particularly well suited for propulsion system applications since they allow for the easy ejection of thrust producing plasma. Currently, the MSFC GDM is constructed in three segments. The vacuum chamber mirror segment, the plasma injector mirror segment, and the main plasma chamber segment. Enough magnets are currently available to construct up to three main plasma chamber segments. The mirror segments are also segmented such that they can be expanded to accommodate new end plugging strategies with out requiring the disassembly of the entire mirror segment. The plasma for the experiment is generated in a microwave cavity located between the main magnets and the mirror magnets. Ion heating is accomplished through ambipolar diffusion. The objective of the experiment is to investigate the stability characteristics of the gasdynamic mirror and to map a region of parameter space within which the plasma can be confined in a stable steady state configuration. The mirror ratio, plasma density, and plasma "b" will be varied over a range of values and measurements subsequently taken to determine the degree of plasma stability.

  7. A co-phasing technique for segmented mirror telescopes

    NASA Astrophysics Data System (ADS)

    Jacob, Annu; Parihar, Padmakar

    2015-06-01

    In the new era of astronomy, we go for bigger telescopes having segmented primary and secondary mirrors. But once segmentation is done, aligning and phasing mirror segments so that altogether they act like a monolithic mirror of a large diameter, becomes critical. Co-phasing is a complex task that needed to be done after aligning the segments. Diffraction limited resolution is only possible by a large segmented telescope, if mirror segments are co-phased. Co-phasing techniques rely on physical optics and in one of the technique implemented in Keck telescope is based on analysis of diffraction pattern generated by Shack Hartmann sensor. This same technique is being further explored by us in laboratory experimentation. In this paper we present our effort to develop a simple but robust phasing technique for a large segmented mirror telescope proposed to be installed in India. After rigorous mathematical exercise , analytical formulation for the phasing technique is derived, which is further used to simulate in MATLAB. The MATLAB results are cross checked with the ZEMAX. There after, a preliminary laboratory experiment has been conducted to check the feasibility of using this technique for phasing segmented mirrors.

  8. Relay mirror experiment

    NASA Astrophysics Data System (ADS)

    Begley, David L.

    1996-04-01

    Originating out of a SDIO-funded, Phase 1 study effort, two ground systems and an orbiting EO payload/spacecraft were the primary equipment for the RME. The RME was originally conceived to be a shuttle deployed experiment. Shortly after program start, the Challenger disaster occurred, with the promise of extensive delays. A completely new space segment was to be designed incorporating a free-flying spacecraft. During the midphase of the program, a variety of launch vehicles were envisioned to replace the shuttle, requiring the BASD team to design accommodations for Delta, Atlas, and Titan, with a Delta launch being the final solution. The ground systems tracked the spacecraft and illuminated it with green and blue beacon lasers. The Payload Experiment Package (PEP) housed the bisection tracker, a key innovation central to the experiment. The bisection tracker acquired both beacons and controlled steerable mirrors to accomplish fine tracking of the two cooperative beacons. In the process, the relay mirror was precisely positioned to enable a successful relay of a third infrared laser between the two ground sites via the orbiting spacecraft. Many of the key technologies employed in the PEP were originally developed for Ball laser communications research and development programs and other laser pointing efforts. The WAVE sensor package, built by ATA and integrated by Ball, measured the vibrations of the optical base structure on which it was mounted. These spacecraft vibration data are critical to the accurate pointing of space laser communication terminals.

  9. Mirror development for CTA

    NASA Astrophysics Data System (ADS)

    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.

  10. "Mirror-Image" Errors without Mirror-Image Stimuli

    ERIC Educational Resources Information Center

    Barroso, Felix; Braine, Lila Ghent

    1974-01-01

    Young children matching the orientation of (a) identical realistic figures that could form mirror images of each other, or (b) nonidentical realistic figures that could not form mirror images, produced the same pattern of errors. The explanation proposed is a strategy of matching analogous parts of the two figures. (Author/SDH)

  11. ESO adaptive optics facility progress report

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

    The ESO Adaptive Optics Facility (AOF) consists in an evolution of one of the ESO VLT unit telescopes to a laser driven adaptive telescope with a deformable mirror in its optical train. The project has completed the procurement phase and several large structures have been delivered to Garching (Germany) and are being integrated (the AO modules GRAAL and GALACSI and the ASSIST test bench). The 4LGSF Laser (TOPTICA) has undergone final design review and a pre-production unit has been built and successfully tested. The Deformable Secondary Mirror is fully integrated and system tests have started with the first science grade thin shell mirror delivered by SAGEM. The integrated modules will be tested in stand-alone mode in 2012 and upon delivery of the DSM in late 2012, the system test phase will start. A commissioning strategy has been developed and will be updated before delivery to Paranal. A substantial effort has been spent in 2011-2012 to prepare the unit telescope to receive the AOF by preparing the mechanical interfaces and upgrading the cooling and electrical network. This preparation will also simplify the final installation of the facility on the telescope. A lot of attention is given to the system calibration, how to record and correct any misalignment and control the whole facility. A plan is being developed to efficiently operate the AOF after commissioning. This includes monitoring a relevant set of atmospheric parameters for scheduling and a Laser Traffic control system to assist the operator during the night and help/support the observing block preparation.

  12. Mirror profile optimization for nano-focusing KB mirror

    SciTech Connect

    Zhang Lin; Baker, Robert; Barrett, Ray; Cloetens, Peter; Dabin, Yves

    2010-06-23

    A KB focusing mirror width profile has been optimized to achieve nano-focusing for the nano-imaging end-station ID22NI at the ESRF. The complete mirror and flexure bender assembly has been modeled in 3D with finite element analysis using ANSYS. Bender stiffness, anticlastic effects and geometrical non-linear effects have been considered. Various points have been studied: anisotropy and crystal orientation, stress in the mirror and bender, actuator resolution and the mirror-bender adhesive bonding... Extremely high performance of the mirror is expected with residual slope error smaller than 0.6 {mu}rad, peak-to-valley, compared to the bent slope of 3000 {mu}rad.

  13. Successful Graded Mirror Therapy in a Patient with Chronic Deafferentation Pain in Whom Traditional Mirror Therapy was Ineffective: A Case Report.

    PubMed

    Mibu, Akira; Nishigami, Tomohiko; Tanaka, Katsuyoshi; Osumi, Michihiro; Tanabe, Akihito

    2016-04-01

    A 43-year-old man had deafferentation pain in his right upper extremity secondary to brachial plexus avulsion from a traffic accident 23 years previously. On our initial examination, he had severe tingling pain with numbness in the right fingers rated 10 on the numerical rating scale. The body perception of the affected third and fourth fingers was distorted in the flexed position. Although he performed traditional mirror therapy (TMT) for 4 weeks in the same methods as seen in previous studies, he could not obtain willed motor imagery and pain-alleviation effect. Therefore, we modified the task of TMT: Graded mirror therapy (GMT). GMT consisted of five stages: (1) observation of the mirror reflection of the unaffected side without imagining any movements of the affected side; (2) observation of the mirror reflection of the third and fourth fingers changing shape gradually adjusted from a flexed position to a extended position; (3) observation of the mirror reflection of passive movement; (4) motor imagery of affected fingers with observation of the mirror reflection (similar to TMT); (5) motor imagery of affected fingers without mirror. Each task was performed for 3 to 4 weeks. As a result, pain intensity during mirror therapy gradually decreased and finally disappeared. The body perception of the affected fingers also improved, and he could imagine the movement of the fingers with or without mirror. We suggested that GMT starting from the observation task without motor imagery may effectively decrease deafferentation pain compared to TMT. PMID:26914841

  14. Progress on the development of a zonal bimorph deformable mirror

    NASA Astrophysics Data System (ADS)

    Griffith, Mike S.; Laycock, Leslie C.; Archer, Nick; Myers, Richard; Doel, Peter; Birch, Rolf

    2008-07-01

    The Zonal Bimorph Deformable Mirror (ZBDM) is a new concept of adaptive mirror. It exploits the benefits normally associated with bimorph mirrors, namely simple rugged construction, low capacitance, and cost effectiveness, but in a significant departure from classical, edge supported bimorphs each element is supported from underneath. This results in a localised (zonal) response and enables the device to be scalable up to large aperture, multi-1000 element devices. Crucially, the combination of continuous support coupled with the use of flexi-circuit interconnect promotes the assembly of a high density 'tweeter' deformable mirror (DM) onto a lower density, high dynamic range 'woofer' DM to generate an integrated, dual-stage deformable mirror which can deliver both high resolution and high dynamic range simultaneously. Such a device has the potential to significantly simplify the design of astronomical adaptive optics (AO) systems. We present the progress made on the development of the ZBDM as part of a collaborative project funded by the newly formed UK Science and Technology Facilities Council.

  15. Deformable mirror interferometric analysis for the direct imagery of exoplanets

    NASA Astrophysics Data System (ADS)

    Mazoyer, Johan; Galicher, Raphaël.; Baudoz, Pierre; Lanzoni, Patrick; Zamkotsian, Frédéric; Rousset, Gérard

    2014-07-01

    Direct imaging of exoplanet systems requires the use of coronagraphs to reach high contrast levels (10-8 to 10-11) at small angular separations (0.100). However, the performance of these devices is drastically limited by aberrations (in phase or in amplitude, introduced either by atmosphere or by the optics). Coronagraphs must therefore be combined with extreme adaptive optic systems, composed of a focal plane wavefront sensor and of a high order deformable mirror. These adaptive optic systems must reach a residual error in the corrected wavefront of less than 0.1 nm (RMS) with a rate of 1 kHz. In addition, the surface defects of the deformable mirror, inherent from the fabrication process, must be limited in order to avoid the introduction of amplitude aberrations. An experimental high contrast bench has been developed at the Paris Observatory (LESIA). This bench includes a Boston Micromachine deformable mirror composed of 1024 actuators. For a precise analysis of its surface and performance, we characterized this mirror on the interferometric bench developed since 2004 at the Marseille Observatory (LAM). In this paper, we present this interferometric bench as well as the results of the analysis. This will include a precise surface characterization and a description of the behavior of the actuators, on a 10 by 10 actuator range (behavior of a single actuator, study of the cross-talk between neighbor actuators, influence of a stuck actuator) and on full mirror scale (general surface shape).

  16. Alignment and integration of ASSIST: a test bench for VLT adaptive optics facility

    NASA Astrophysics Data System (ADS)

    Deep, Atul; Arsenault, Robin; Boland, Wilfried; Delabre, Bernard; Hubin, Norbert; La Penna, Paolo; Madec, Pierre-Yves; Molster, Frank; Stuik, Remko; Tordo, Sebastien; Wiegers, Emiel

    2010-08-01

    ASSIST, The Adaptive Secondary Setup and Instrument STimulator, is being developed to provide a testing facility for the ESO Adaptive Optics Facility (AOF). It will allow the off-telescope testing of three elements of the VLT AOF; the Deformable Secondary Mirror (DSM) and the AO systems for MUSE and HAWK-I (GALACSI and GRAAL). The core of ASSIST consists of a 2-mirror setup (AM1-AM2) allowing the on-axis test of the DSM in interferometric mode. However, during the initial stages of ASSIST integration, DSM would not be present. This makes the task of aligning AM1-AM2 to within an accuracy of 0.05mm/1 arcmin rather challenging. A novel technique known as Shack-Hartmann method has been developed and tested in the lab for this purpose. A Shack Hartmann wavefront sensor will be used to measure the mis-alignment between AM1-AM2 by recording the coma and astigmatism in the presence of large spherical aberration introduced because of tilt/decenter of AM2 with respect to AM1. Thereafter, 20 optical components including lenses, flat mirrors and beam-splitter cubes divided into five sub-assemblies should be aligned to AM1-AM2- DSM axis which ultimately passes through the mechanical axis of large AMOS rotator.

  17. Adaptive Optics Facility Status Report: When First Light Is Produced Rather Than Captured

    NASA Astrophysics Data System (ADS)

    Arsenault, R.; Madec, P.-Y.; Vernet, E.; Hackenberg, W.; Bonaccini Calia, D.; La Penna, P.; Paufique, J.; Kuntschner, H.; Pirard, J.-F.; Sarazin, M.; Haguenauer, P.; Hubin, N.; Vera, I.

    2016-06-01

    First light for the 4 Laser Guide Star Facility (4LGSF) took place in Paranal on 26 April 2016 with four laser units in operation for the first time. A combined test with the first laser guide star unit and the Ground Layer Adaptive optics Assisted by Lasers (GRAAL) instrument in October 2015 demonstrated the whole acquisition sequence of the Adaptive Optics Facility (AOF). Many tools that will support the operation of the AOF for science observations have meanwhile been implemented. GALACSI was granted Provisional Acceptance in Europe in April 2016, completing the system tests and qualification in Garching of the adaptive optics modules GRAAL and GALACSI (Ground Atmospheric Layer Adaptive Optics for Spectroscopic Imaging), their real-time computers and the deformable secondary mirror (DSM). Results of tests both in the laboratory and on sky are presented. The installation of the DSM and GALACSI will be completed by early 2017, to be followed by commissioning of all AOF systems.

  18. Forming Mirrors on Composite Materials

    NASA Technical Reports Server (NTRS)

    Gauldin, R. E.; Ramohalli, K.

    1983-01-01

    Smooth coatings deposited on hard-to-polish substrates. Lightweight mirror, leaning against conventional glass mirror, consists of metallic relective layer on substrate coated with polyester resin. Smooth surface of polyester resin made by covering freshly applied resin with piece of smooth glass coated with release agent.

  19. Polishing technique for beryllium mirror

    NASA Technical Reports Server (NTRS)

    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.

  20. Acoustic Models of Optical Mirrors

    ERIC Educational Resources Information Center

    Mayer, V. V.; Varaksina, E. I.

    2014-01-01

    Students form a more exact idea of the action of optical mirrors if they can observe the wave field being formed during reflection. For this purpose it is possible to organize model experiments with flexural waves propagating in thin elastic plates. The direct and round edges of the plates are used as models of plane, convex and concave mirrors.…

  1. Stroke amplifier for deformable mirrors

    PubMed Central

    Webb, Robert H.; Albanese, Marc J.; Zhou, Yaopeng; Bifano, Thomas; Burns, Stephen A.

    2010-01-01

    We demonstrate a simple optical configuration that amplifies the usable stroke of a deformable mirror. By arranging for the wavefront to traverse the deformable mirror more than once, we correct it more than once. The experimental implementation of the idea demonstrates a doubling of 2.0 and 2.04 by two different means. PMID:15495423

  2. Commissioning results of MMT-POL: the 1-5um imaging polarimeter leveraged from the AO secondary of the 6.5m MMT

    NASA Astrophysics Data System (ADS)

    Packham, C.; Jones, T. J.; Warner, C.; Krejny, M.; Shenoy, D.; Vonderharr, T.; Lopez-Rodriguez, E.; DeWahl, K.

    2012-09-01

    MMT-POL is an adaptive optics optimized imaging polarimeter designed for use at the 6.5m MMT. By taking full advantage of the adaptive optics secondary mirror of the MMT, this polarimeter offers diffraction-limited polarimetry with very low instrumental polarization and minimal thermal background. MMT-POL permits observations as diverse as protoplanetary discs, comets, red giant winds, (super)novae and ejecta, galaxies, and AGN. We report on the initial on-sky commissioning results of the instrument including a description of the instrument.

  3. Lightweight tip-tilt mirror in correlation tracker system of the Space Solar Telescope

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Yang, Shimo; Jiang, Aimin

    2005-12-01

    To compensate the image motion caused by random atmospheric turbulence and mechanical vibration, a high performance correlation tracker designed for the Space Solar Telescope (SST) has been realized in National Astronomical Observatories. Correlation tracker is to stabilize the image and provide the stabilized objective to CCD. The main optical telescope can obtain the highest spatial resolution and ensure the image processing. Tip-tilt mirror is the crucial element of the correlation tracker. The lightweight mirror is to adapt to work normally with space using and satisfy the space environmental requirement. Tip-tilt mirror's material is SiC. Confirming the appropriate joint with the platform and supporting mode through Finite Element Method. Then calculating the surface shape quality value (RMS) of the mirror effected by inertial load and temperature. The calculation results show that the tip-tilt mirror has enough stiffness and intensity. The mirror's surface shape quality value can satisfy the optical requirement of the correlation tracker system.

  4. Electrons and Mirror Symmetry

    ScienceCinema

    Kumar, Krishna

    2009-09-01

    The neutral weak force between an electron and a target particle, mediated by the Z boson, can be isolated by measuring the fractional change under a mirror reflection of the scattering probability of relativistic longitudinally polarized electrons off unpolarized targets. This technique yields neutral weak force measurements at a length scale of 1 femtometer, in contrast to high energy collider measurements that probe much smaller length scales. Study of the variation of the weak force over a range of length scales provides a stringent test of theory, complementing collider measurements. We describe a recent measurement of the neutral weak force between two electrons by the E158 experiment at the Stanford Linear Accelerator Center. While the weak force between an electron and positron has been extensively studied, that between two electrons had never directly been measured. We conclude by discussing prospects for even more precise measurements at future facilities.

  5. Electrons and Mirror Symmetry

    SciTech Connect

    Kumar, Krishna

    2007-04-04

    The neutral weak force between an electron and a target particle, mediated by the Z boson, can be isolated by measuring the fractional change under a mirror reflection of the scattering probability of relativistic longitudinally polarized electrons off unpolarized targets. This technique yields neutral weak force measurements at a length scale of 1 femtometer, in contrast to high energy collider measurements that probe much smaller length scales. Study of the variation of the weak force over a range of length scales provides a stringent test of theory, complementing collider measurements. We describe a recent measurement of the neutral weak force between two electrons by the E158 experiment at the Stanford Linear Accelerator Center. While the weak force between an electron and positron has been extensively studied, that between two electrons had never directly been measured. We conclude by discussing prospects for even more precise measurements at future facilities.

  6. The kinaesthetic mirror illusion: How much does the mirror matter?

    PubMed

    Chancel, Marie; Brun, Clémentine; Kavounoudias, Anne; Guerraz, Michel

    2016-06-01

    The reflection of a moving hand in a mirror positioned in the sagittal plane can create an illusion of symmetrical, bimanual movement. This illusion is implicitly presumed to be of visual origin. However, muscle proprioceptive afferents of the arm reflected in the mirror might also affect the perceived position and movement of the other arm. We characterized the relative contributions of visual and proprioceptive cues by performing two experiments. In Experiment 1, we sought to establish whether kinaesthetic illusions induced using the mirror paradigm would survive marked visual impoverishment (obtained by covering between 0 and 100 % of the mirror in 16 % steps). We found that the mirror illusion was only significantly influenced when the visual degradation was 84 % or more. In Experiment 2, we masked the muscle proprioceptive afferents of the arm reflected in the mirror by co-vibrating antagonistic muscles. We found that masking the proprioceptive afferents reduced the velocity of the illusory displacement of the other arm. These results confirm that the mirror illusion is not a purely visual illusion but emerges from a combination of congruent signals from the two arms, i.e. visual afferents from the virtually moving arm and proprioceptive afferents from the contralateral, moving arm. PMID:26790422

  7. Mirror man: a case of skilled deliberate mirror writing.

    PubMed

    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. PMID:24593311

  8. Point Relay Scanner Utilizing Ellipsoidal Mirrors

    NASA Technical Reports Server (NTRS)

    Manhart, Paul K. (Inventor); Pagano, Robert J. (Inventor)

    1997-01-01

    A scanning system uses a polygonal mirror assembly with each facet of the polygon having an ellipsoidal mirror located thereon. One focal point of each ellipsoidal mirror is located at a common point on the axis of rotation of the polygonal mirror assembly. As the mirror assembly rotates. a second focal point of the ellipsoidal mirrors traces out a scan line. The scanner can be utilized for scanned output display of information or for scanning information to be detected.

  9. High repetition rate plasma mirror device for attosecond science

    SciTech Connect

    Borot, A.; Douillet, D.; Iaquaniello, G.; Lefrou, T.; Lopez-Martens, R.; Audebert, P.; Geindre, J.-P.

    2014-01-15

    This report describes an active solid target positioning device for driving plasma mirrors with high repetition rate ultra-high intensity lasers. The position of the solid target surface with respect to the laser focus is optically monitored and mechanically controlled on the nm scale to ensure reproducible interaction conditions for each shot at arbitrary repetition rate. We demonstrate the target capabilities by driving high-order harmonic generation from plasma mirrors produced on glass targets with a near-relativistic intensity few-cycle pulse laser system operating at 1 kHz. During experiments, residual target surface motion can be actively stabilized down to 47 nm (root mean square), which ensures sub-300-as relative temporal stability of the plasma mirror as a secondary source of coherent attosecond extreme ultraviolet radiation in pump-probe experiments.

  10. High repetition rate plasma mirror device for attosecond science

    NASA Astrophysics Data System (ADS)

    Borot, A.; Douillet, D.; Iaquaniello, G.; Lefrou, T.; Audebert, P.; Geindre, J.-P.; Lopez-Martens, R.

    2014-01-01

    This report describes an active solid target positioning device for driving plasma mirrors with high repetition rate ultra-high intensity lasers. The position of the solid target surface with respect to the laser focus is optically monitored and mechanically controlled on the nm scale to ensure reproducible interaction conditions for each shot at arbitrary repetition rate. We demonstrate the target capabilities by driving high-order harmonic generation from plasma mirrors produced on glass targets with a near-relativistic intensity few-cycle pulse laser system operating at 1 kHz. During experiments, residual target surface motion can be actively stabilized down to 47 nm (root mean square), which ensures sub-300-as relative temporal stability of the plasma mirror as a secondary source of coherent attosecond extreme ultraviolet radiation in pump-probe experiments.

  11. High repetition rate plasma mirror device for attosecond science.

    PubMed

    Borot, A; Douillet, D; Iaquaniello, G; Lefrou, T; Audebert, P; Geindre, J-P; Lopez-Martens, R

    2014-01-01

    This report describes an active solid target positioning device for driving plasma mirrors with high repetition rate ultra-high intensity lasers. The position of the solid target surface with respect to the laser focus is optically monitored and mechanically controlled on the nm scale to ensure reproducible interaction conditions for each shot at arbitrary repetition rate. We demonstrate the target capabilities by driving high-order harmonic generation from plasma mirrors produced on glass targets with a near-relativistic intensity few-cycle pulse laser system operating at 1 kHz. During experiments, residual target surface motion can be actively stabilized down to 47 nm (root mean square), which ensures sub-300-as relative temporal stability of the plasma mirror as a secondary source of coherent attosecond extreme ultraviolet radiation in pump-probe experiments. PMID:24517742

  12. Magnet Loader for Schmidt-Cassegrain Mirror Flop Reduction

    NASA Astrophysics Data System (ADS)

    Vander Haagen, G. A.

    2006-05-01

    The struggle with mechanical and optical issues in most commercially available Schmidt-Cassegrain amateur telescopes is exacerbated by the random flop of the primary mirror as it progresses beyond the meridian. Several retrofit techniques are available to reduce this problem, including lock-down screws and collars. Such approaches all require some modification to the optical tube. This paper discusses "work-in-progress" on a Magnetic Loader for the popular C14 optical tube that locates a rare-earth magnetic assembly on the primary mirror collar thereby continuously loading the sleeve bearing assembly. This technique requires no machined modifications or parts, can be accomplished by removal of the secondary mirror, and requires no operator intervention during focusing. While the initial data looks favorable, additional development and testing over a wider range of conditions is necessary.

  13. High heat flux mirror design for an undulator beamline

    NASA Astrophysics Data System (ADS)

    Tonnessen, Thomas W.; Fisher, Steven E.; Anthony, Frank M.; Lunt, David L.; Khounsary, Ali M.; Randall, Kevin J.; Gluskin, Efim S.; Yun, Wenbing

    1993-11-01

    A-high-heat-load, horizontally deflecting/focusing mirror is designed for installation on an APS undulator beamline. The main design objective has been to keep the total tangential RMS slope error, including the thermally induced component, to less than 2 (mu) rad with an absorbed beam power on the mirror of 2 kW and a peak flux of 3.2 W/mm2. Extensive examination of various design parameters and detailed thermal/structural analyses has resulted in a mirror design that meets the tight slope-error requirement. Design features include a silicon substrate, a tailored pin-post cooling scheme, a moderate coolant flow rate, primary and secondary cooling areas, a multi-strip coating on the reflecting surface, and inlet/outlet cooling manifolds through an attached Ni-Fe mounting structure.

  14. Active control of a large deformable mirror for future E-ELT

    NASA Astrophysics Data System (ADS)

    Gasmi, R.; Le Bihan, D.; Dournaux, J. L.; Sinquin, J. C.; Jagourel, P.

    2010-07-01

    Increasing dimensions of ground based telescopes and adaptive optics needs for these instruments require wide deformable mirrors with a high number of actuators to compensate the effects of the atmospheric turbulence on the wave fronts. The new dimensions and characteristics of these deformable mirrors lead to the apparition of structural vibrations, which may reduce the rejection band width of the adaptive optics control loop. The aim of this paper is the study of the dynamic behavior of a 1-meter prototype of E-ELT's deformable mirror in order to identify its eigenmodes and to propose some ways to control its vibrations. We first present the first eigenmodes of the structure determined by both finite element analysis and experimental modal analysis. Then we present the frequency response of the prototype to a tilt excitation to estimate the effects of its vibrations on the adaptive optics loop. Finally we suggest a method to control the dynamics of the deformable mirror.

  15. Advanced Mirror & Modelling Technology Development

    NASA Technical Reports Server (NTRS)

    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.

  16. Observational physics of mirror world

    NASA Technical Reports Server (NTRS)

    Khlopov, M. YA.; Beskin, G. M.; Bochkarev, N. E.; Pustilnik, L. A.; Pustilnik, S. A.

    1989-01-01

    The existence of the whole world of shadow particles, interacting with each other and having no mutual interactions with ordinary particles except gravity is a specific feature of modern superstring models, being considered as models of the theory of everything. The presence of shadow particles is the necessary condition in the superstring models, providing compensation of the asymmetry of left and right chirality states of ordinary particles. If compactification of additional dimensions retains the symmetry of left and right states, shadow world turns to be the mirror one, with particles and fields having properties strictly symmetrical to the ones of corresponding ordinary particles and fields. Owing to the strict symmetry of physical laws for ordinary and mirror particles, the analysis of cosmological evolution of mirror matter provides rather definite conclusions on possible effects of mirror particles in the universe. A general qualitative discussion of possible astronomical impact of mirror matter is given, in order to make as wide as possible astronomical observational searches for the effects of mirror world, being the unique way to test the existence of mirror partners of ordinary particles in the Nature.

  17. Stressed mirror polishing: finite element simulation of mirror blank deformation

    NASA Astrophysics Data System (ADS)

    Han, Yu; Lu, Lihong

    2014-08-01

    The theoretical principle of Stressed Mirror Polishing (SMP) is introduced, including the representation method of elastic deformation, the formulations of discrete bending moment and shearing force. A Finite Element Analysis (FEA) simulation model of has been set up by ANSYS software. The warping facility in this model is consisted of 36 aluminum alloy arms equally distribute on the ambit of mirror blank. Two forces are applied on each arm to provide bending moment and shearing force. Taking type 82 segment of Thirty Meters Telescope (TMT) primary mirror for example, a FEA simulation of mirror blank deformation has been performed. Simulation result shows that, the deformation error is 33μm PV. The theoretical deformation PV value is 205μm and the simulation deformation PV value is 172μm, converging rate reaches to 0.84 in a single warping cycle. After three or four warping cycles, the residue error may converge into 1μm.

  18. Issues in the design and optimization of adaptive optics and laser guide stars for the Keck Telescopes

    SciTech Connect

    Max, C.E.; Gavel, D.T.; Olivier, S.S.

    1994-03-01

    We discuss issues in optimizing the design of adaptive optics and laser guide star systems for the Keck Telescope. The initial tip-tilt system will use Keck`s chopping secondary mirror. We describe design constraints, choice of detector, and expected performance of this tip-tilt system as well as its sky coverage. The adaptive optics system is being optimized for wavelengths of I-2.2{mu}m. We are studying adaptive optics concepts which use a wavefront sensor with varying numbers of subapertures, so as to respond to changing turbulence conditions. The goal is to be able to ``gang together`` groups of deformable mirror subapertures under software control, when conditions call for larger subapertures. We present performance predictions as a function of sky coverage and the number of deformable mirror degrees of freedom. We analyze the predicted brightness several candidate laser guide star systems, as a function of laser power and pulse format. These predictions are used to examine the resulting Strehl as a function of observing wavelength and laser type. We discuss laser waste heat and thermal management issues, and conclude with an overview of instruments under design to take advantage of the Keck adaptive optics system.

  19. Kodak AMSD Mirror Development Program

    NASA Technical Reports Server (NTRS)

    Matthews, Gary; Dahl, Roger; Barrett, David; Bottom, John; Russell, Kevin (Technical Monitor)

    2002-01-01

    The Advanced Mirror System Demonstration Program is developing minor technology for the next generation optical systems. Many of these systems will require extremely lightweight and stable optics due to the overall size of the primary mirror. These segmented, deployable systems require new technology that AMSD is developing. The on-going AMSD program is a critical enabler for Next Generation Space Telescope (NGST) which will start in 2002. The status of Kodak's AMSD mirror and future plans will be discussed with respect to the NGST program.

  20. JWST NIRCam flight mirror assemblies

    NASA Astrophysics Data System (ADS)

    Mammini, Paul V.; Holmes, Howard C.; Huff, Lynn; Jacoby, Mike S.; Lopez, Frank

    2011-10-01

    The Near Infrared Camera (NIRCam) instrument for NASA's James Webb Space Telescope (JWST) has an optical prescription which includes numerous fold mirror assemblies. The instrument will operate at 35K after experiencing launch loads at ~293K. The optic mounts must accommodate all associated thermal and mechanical stresses, plus maintain exceptional optical quality during operation. Lockheed Martin Space Systems Company (LMSSC) conceived, designed, analyzed, assembled, tested, and integrated the mirror assemblies for the NIRCam instrument. This paper covers the design, analysis, assembly, and test of two of the instruments key fold mirrors.

  1. Fueling of tandem mirror reactors

    SciTech Connect

    Gorker, G.E.; Logan, B.G.

    1985-01-01

    This paper summarizes the fueling requirements for experimental and demonstration tandem mirror reactors (TMRs), reviews the status of conventional pellet injectors, and identifies some candidate accelerators that may be needed for fueling tandem mirror reactors. Characteristics and limitations of three types of accelerators are described; neutral beam injectors, electromagnetic rail guns, and laser beam drivers. Based on these characteristics and limitations, a computer module was developed for the Tandem Mirror Reactor Systems Code (TMRSC) to select the pellet injector/accelerator combination which most nearly satisfies the fueling requirements for a given machine design.

  2. Polarimetry with multiple mirror telescopes

    NASA Technical Reports Server (NTRS)

    West, S. C.

    1986-01-01

    The polarizations of multiple mirror telescopes are calculated using Mueller calculus. It is found that the Multiple Mirror Telescope (MMT) produces a constant depolarization that is a function of wavelength and independent of sky position. The efficiency and crosstalk are modeled and experimentally verified. The two- and four-mirror new generation telescopes are found to produce sinusoidal depolarization for which an accurate interpretation of the incident Stokes vector requires inverse matrix calculations. Finally, the depolarization of f/1 paraboloids is calculated and found to be less than 0.1 percent at 3000 A.

  3. Evanescent Wave Atomic Mirror

    NASA Astrophysics Data System (ADS)

    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

  4. Deformable mirror with combined piezoelectric and electrostatic actuators

    NASA Astrophysics Data System (ADS)

    Merkle, F.; Freischlad, K.; Reischmann, H.-L.

    1982-10-01

    An adaptive optics system with modal phase correction for reconstituting astronomical images passing through the atmosphere is described. An active mirror in a gimbal mount houses an electrostatic deformable membrane for the modal corrections. Piezoelectric actuators are attached behind the mirror for tilt correction. Wavefronts triggering the electrode detectors in the mirror also result in generation of a map of the wave-front errors. Compensating phase distributions for successive waves are calculated automatically by an expansion of the phase distortions into modes of a set of basis functions. Turbulence compensation is accomplished with Zernike polynomials if only a small number of modes is present, while Karhunen-Loeve functions serve for any number of modes. Phase aberrations are detected by diode arrays connected to amplifier tubes. Actual measurement of the wavefront phase is performed by a shearing interferometer and by use of an iterative algorithm to assay the intensity distribution of the image.

  5. A new piston control strategy for segmented mirrors

    NASA Technical Reports Server (NTRS)

    Olivier, Philip D.

    1994-01-01

    One approach to the adaptive control of large segmented mirrors involves sending tilt commands to each segment and allowing each segment to minimize the distance between its edges and those of (all or some of) its neighbors. This approach has been adopted in the Phased Array Mirror, Extendible Large Aperture (PAMELA) testbed now located at NASA's Marshall Space Flight Center, Huntsville, AL. This approach minimizes (1) the communication between the sensors and the segment actuators and (2) computations required by the central controlling computer. This report discusses issues that large segmented mirrors built around the PAMELA concept (such as SELENE) will face when they migrate to integrated, and presumably to digital, on-segment computational ability and high bandwidth response.

  6. Tinbergen on mirror neurons

    PubMed Central

    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. PMID:24778376

  7. Responder fast steering mirror

    NASA Astrophysics Data System (ADS)

    Bullard, Andrew; Shawki, Islam

    2013-09-01

    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.

  8. Responder fast steering mirror

    NASA Astrophysics Data System (ADS)

    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.

  9. Experimental and simulation study of undesirable short-period deformation in piezoelectric deformable x-ray mirrors

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    To construct adaptive x-ray focusing optics whose optical parameters can be varied while performing wavefront correction, ultraprecise piezoelectric deformable mirrors have been developed. We computationally and experimentally investigated undesirable short-period deformation caused by piezoelectric actuators adhered to the substrate during mirror deformation. Based on the results of finite element method analysis, shape measurements, and the observation of x-ray reflection images, a guideline is developed for designing deformable mirrors that do not have short-period deformation errors.

  10. The magic of relay mirrors

    NASA Astrophysics Data System (ADS)

    Duff, Edward A.; Washburn, Donald C.

    2004-09-01

    Laser weapon systems would be significantly enhanced with the addition of high altitude or space-borne relay mirrors. Such mirrors, operating alone with a directed energy source, or many in a series fashion, can be shown to effectively move the laser source to the last, so-called fighting mirror. This "magically" reduces the range to target and offers to enhance the performance of directed energy systems like the Airborne Laser and even ground-based or ship-based lasers. Recent development of high altitude airships will be shown to provide stationary positions for such relay mirrors thereby enabling many new and important applications for laser weapons. The technical challenges to achieve this capability are discussed.

  11. JWST Primary Mirror Installation Complete

    NASA Video Gallery

    Completing the assembly of the primary mirror, which took place at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is a significant milestone and the culmination of over a decade of desi...

  12. Morphing of Segmented Bimorph Mirrors

    NASA Astrophysics Data System (ADS)

    Rodrigues, Gonçalo; Bastaits, Renaud; Preumont, André

    2010-08-01

    Atmospheric turbulence compensation for the next generation of terrestrial telescopes (30-40 m diameter) will require deformable mirrors of increasing size and a number of actuators reaching several thousands. However, the mere extrapolation of existing designs leads to complicated and extremely expensive mirrors. This article discusses an alternative solution based on the use of segmented identical hexagonal bimorph mirrors. This allows to indefinitely increase the degree of correction while maintaining the first mechanical resonance at the level of a single segment, and shows an increase in price only proportional to the number of segments. Extensive simulations using random turbulent screens show that the segmentation produces only moderate reductions of the Strehl number, compared to a monolithic bimorph mirror with the same number of actuators (S = 0.86 instead of S = 0.89 in this study).

  13. FAME: Freeform Active Mirrors Experiment

    NASA Astrophysics Data System (ADS)

    Hugot, Emmanuel; Agocs, Tibor; Challita, Zalpha; Jasko, Attila; Kroes, Gabby; Banyai, Evelin; Miller, Chris; Taylor, William; Schnetler, Hermine; Venema, Lars

    2014-07-01

    This paper discusses the development of a demonstrator freeform active mirror for future astronomical instruments both on Earth and in space. It consists of a system overview and progress in various areas of technology in the building blocks of the mirror: an extreme freeform thin face sheet, an active array, design tools and the metrology and control of the system. The demonstrator aims to investigate the applicability of the technique in high end astronomical systems, also for space and cryogenically.

  14. High temperature current mirror amplifier

    DOEpatents

    Patterson, III, Raymond B.

    1984-05-22

    A high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg.

  15. Ultraviolet-Induced Mirror Degradation

    NASA Technical Reports Server (NTRS)

    Bouquet, F. L.; Hasegawa, T. T.; Cleland, E. L.

    1982-01-01

    Recent tests of second-surface mirrors show that ultraviolet radiation penetrates glass and metalized zone and impinges upon backing paint. According to report, many backing materials are degraded by ultraviolet radiation. Mirror corrosion is a serious problem in solar-energy collection systems. Effects of UV on polymeric materials have been studied, and in general, all are degraded by UV. Polymers most resistant to UV radiation are polyimides.

  16. Some Reflections on Plane Mirrors and Images.

    ERIC Educational Resources Information Center

    Galili, Igal; And Others

    1991-01-01

    Discusses the following questions based on the assumption that students' personal experiences and prior beliefs about plane mirrors can promote interesting discussions: (1) How mirror images are formed? (2) Why doesn't paper behave like a mirror? (3) Does a mirror left-right reverse objects? and (4) Why are corner images of two perpendicular…

  17. Adaptation of the schupmann medial telescope to a large scale astronomical optical system.

    PubMed

    Villa, J J

    1972-08-01

    The classical Schupmann medial telescope is free of the secondary-spectrum residual associated with large refractors. The difficulties in obtaining large glass disks of the necessary optical quality and the problem associated with their mounting preclude the use of this unconventional lens in large scale astronomical systems. However, to circumvent these limitations, the Schupmann lens was modified by replacing the refractive objective with a spherical mirror producing a new catadioptric lens configuration adaptable to large-scale astronomy. The design parameters and performance data are given for an f/5.4, 5.5-m focal length design covering a 2 degrees full field. PMID:20119238

  18. EAGLE: relay mirror technology development

    NASA Astrophysics Data System (ADS)

    Hartman, Mary; Restaino, Sergio R.; Baker, Jeffrey T.; Payne, Don M.; Bukley, Jerry W.

    2002-06-01

    EAGLE (Evolutionary Air & Space Global Laser Engagement) is the proposed high power weapon system with a high power laser source, a relay mirror constellation, and the necessary ground and communications links. The relay mirror itself will be a satellite composed of two optically-coupled telescopes/mirrors used to redirect laser energy from ground, air, or space based laser sources to distant points on the earth or space. The receiver telescope captures the incoming energy, relays it through an optical system that cleans up the beam, then a separate transmitter telescope/mirror redirects the laser energy at the desired target. Not only is it a key component in extending the range of DoD's current laser weapon systems, it also enables ancillary missions. Furthermore, if the vacuum of space is utilized, then the atmospheric effects on the laser beam propagation will be greatly attenuated. Finally, several critical technologies are being developed to make the EAGLE/Relay Mirror concept a reality, and the Relay Mirror Technology Development Program was set up to address them. This paper will discuss each critical technology, the current state of the work, and the future implications of this program.

  19. Evolution of the mirror machine

    SciTech Connect

    Damm, C. C.

    1983-08-18

    The history of the magnetic-mirror approach to a fusion reactor is primarily the history of our understanding and control of several crucial physics issues, coupled with progress in the technology of heating and confining a reacting plasma. The basic requirement of an MHD-stable plasma equilibrium was achieved following the early introduction of minimum-B multipolar magnetic fields. In refined form, the same magnetic-well principle carries over to our present experiments and to reactor designs. The higher frequency microinstabilities, arising from the non-Maxwellian particle distributions inherent in mirror machines, have gradually come under control as theoretical prescriptions for distribution functions have been applied in the experiments. Even with stability, the classical plasma leakage through the mirrors posed a serious question for reactor viability until the principle of electrostatic axial stoppering was applied in the tandem mirror configuration. Experiments to test this principle successfully demonstrated the substantial improvement in confinement predicted. Concurrent with advances in mirror plasma physics, development of both high-power neutral beam injectors and high-speed vacuum pumping techniques has played a crucial role in ongoing experiments. Together with superconducting magnets, cryogenic pumping, and high-power radiofrequency heating, these technologies have evolved to a level that extrapolates readily to meet the requirements of a tandem mirror fusion reactor.

  20. Polymer glazing for silver mirrors

    SciTech Connect

    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.

  1. National Mirror Fusion Program Plan

    SciTech Connect

    Gerich, C.A.

    1982-08-01

    This Plan is current as of August 1982. The major milestones listed herein represent an aggressive, success-oriented program paced primarily by technical results. Consistent with applicable government policies and the overall program planning of the Department's Office of Fusion Energy, this Plan assumes approval of the Mirror Program's next major step beyond MFTF-B - a deuterium-tritium (D-T) burning engineering reactor called the Fusion Power Demonstration (FPD) facility (formerly the Tandem Mirror Next Step). The near-term goal of the tandem mirror program is to lay the scientific and technical groundwork for an economically attractive, D-T fusion reactor design before the end of the 1980s. Construction of the FPD facility based on the tandem mirror could be initited around 1988. A second phase, complete with a nuclear power blanket demonstration, could be initiated in the mid-1990s, based on nuclear engineering data from a facility such as the Technology Demonstration Facility (TDF) described below. The outline of an acceptable tandem mirror reactor (TMR) design was first published in 1981, and will be further developed and described in the Mirror Advanced Reactor Study (MARS) during FY 1982-1983.

  2. Directly polished lightweight aluminum mirror

    NASA Astrophysics Data System (ADS)

    ter Horst, Rik; Tromp, Niels; de Haan, Menno; Navarro, Ramon; Venema, Lars; Pragt, Johan

    2008-07-01

    During the last ten years, Astron has been a major contractor for the design and manufacturing of astronomical instruments for Space- and Earth based observatories, such as VISIR, MIDI, SPIFFI, X-Shooter and MIRI. The collaboration between optical- and mechanical designers at Astron led to new design philosophies and strategies. Driven by the need to reduce the weight of optically ultra-stiff structures, two promising techniques have been developed in the last years: ASTRON Extreme Lightweighting for mechanical structures and an improved Polishing Technique for Aluminum Mirrors. Using one single material for both optical components and mechanical structure simplifies the design of a cryogenic instrument significantly, it is very beneficial during instrument test and verification, and makes the instrument insensitive to temperature changes. Aluminum has been the main material used for cryogenic optical instruments, and optical aluminum mirrors are generally diamond turned. The application of a polishable hard top coating like nickel removes excess stray light caused by the groove pattern, but limits the degree of lightweighting of the mirrors due to the bi-metal effect. By directly polishing the aluminum mirror surface, the recent developments at Astron allow for using a non-exotic material for light weighted yet accurate optical mirrors, with a lower surface roughness (~1nm RMS), higher surface accuracy and reduced light scattering. This paper presents the techniques, obtained results and a global comparison with alternative lightweight mirror solutions.

  3. Modulations of mirroring activity by desire for social connection and relevance of movement.

    PubMed

    Aragón, Oriana R; Sharer, Elizabeth A; Bargh, John A; Pineda, Jaime A

    2014-11-01

    Mirroring neurons fire both when an individual moves and observes another move in kind. This simulation of others' movements is thought to effortlessly and ubiquitously support empathetic connection and social understanding. However, at times this could be maladaptive. How could a boxer mirror a losing opponent's expressions of fatigue, feeling his weariness, precisely when strength is required? Clearly, the boxer must emotionally disconnect from his opponent and those expressions of fatigue must become irrelevant and not mirrored. But, movements that inform of his opponent's intentions to deliver an incoming blow are quite relevant and still should require mirroring. We tested these dimensions of emotional connectedness and relevance of movement in an electroencephalography experiment, where participants' desires to socially connect with a confederate were manipulated. Before manipulation, all participants mirrored the confederate's purely kinematic (a hand opening and closing) and goal-directed (a hand opening and closing around a token that the participant desired) hand movements. After manipulation, unfairly treated subjects ceased to mirror the purely kinematic movements but continued to mirror goal-relevant movements. Those treated fairly continued to mirror all movements. The results suggest that social mirroring can be adaptive in order to meet the demands of a varied social environment. PMID:24194581

  4. A segmented mirror antenna for radiometers

    NASA Astrophysics Data System (ADS)

    Lee, S. W.; Houshmand, B.; Zimmerman, M.; Acosta, R.

    1989-05-01

    An antenna is designed for the radiometer application of the planned NASA Earth Science Geostationary Platforms in the 1990's. The antenna consists of two parts: a regular parabolic dish of 5 meters in diameter which converts the radiation from feeds into a collimated beam, and a movable mirror that redirects the beam to a prescribed scan direction. The mirror is composed of 28 segmented planar conducting plates, mostly one square meter in size. The secondary pattern of the antenna was analyzed based on a physical optics analysis. For frequencies between 50 and 230 GHz, and for a scan range of + or -8 deg (270 beamwidths scan at 230 GHz), the worst calculated beam efficiency is 95 percent. To cover such a wide frequency and scan range, each of the 28 plates is individually controlled for a tilting less than 4 deg, and for a sliding less than 0.5 cm. The sliding is done at discrete steps. At 230 GHz, a step size of 2 mil is sufficient. The plate positions must be reset for each frequency and for each scan direction. Once the position is set, the frequency bandwidth of the antenna is very narrow.

  5. A segmented mirror antenna for radiometers

    NASA Technical Reports Server (NTRS)

    Lee, S. W.; Houshmand, B.; Zimmerman, M.; Acosta, R.

    1989-01-01

    An antenna is designed for the radiometer application of the planned NASA Earth Science Geostationary Platforms in the 1990's. The antenna consists of two parts: a regular parabolic dish of 5 meters in diameter which converts the radiation from feeds into a collimated beam, and a movable mirror that redirects the beam to a prescribed scan direction. The mirror is composed of 28 segmented planar conducting plates, mostly one square meter in size. The secondary pattern of the antenna was analyzed based on a physical optics analysis. For frequencies between 50 and 230 GHz, and for a scan range of + or -8 deg (270 beamwidths scan at 230 GHz), the worst calculated beam efficiency is 95 percent. To cover such a wide frequency and scan range, each of the 28 plates is individually controlled for a tilting less than 4 deg, and for a sliding less than 0.5 cm. The sliding is done at discrete steps. At 230 GHz, a step size of 2 mil is sufficient. The plate positions must be reset for each frequency and for each scan direction. Once the position is set, the frequency bandwidth of the antenna is very narrow.

  6. On time reversal mirrors

    NASA Astrophysics Data System (ADS)

    Fannjiang, Albert C.

    2009-09-01

    The concept of time reversal (TR) of a scalar wave is reexamined from basic principles. Five different time-reversal mirrors (TRMs) are introduced and their relations are analyzed. For the boundary behavior, it is shown that for a paraxial wave only the monopole TR scheme satisfies the exact boundary condition while for the spherical wave only the MD-mode TR scheme satisfies the exact boundary condition. The asymptotic analysis of the near-field focusing property is presented for two dimensions and three dimensions. It is shown that to have a subwavelength focal spot, the TRM should consist of dipole transducers. The transverse resolution of the dipole TRM is linearly proportional to the distance between the point source and the TRM. The mixed mode TRM has the similar (linear) behavior in three dimensions, but in two dimensions the transverse resolution behaves as the square root of the distance between the point source and the TRM. The monopole TRM is ineffective in focusing below the wavelength. Contrary to the matched field processing and the phase processor, both of which resemble TR, TR in a weak- or non-scattering medium is usually biased in the longitudinal direction, especially when TR is carried out on a single plane with a finite aperture. This is true for all five TR schemes. On the other hand, the TR focal spot has been shown repeatedly in the literature, both theoretically and experimentally, to be centered at the source point when the medium is multiple scattering. A reconciliation of the two seemingly conflicting results is found in the random fluctuations in the intensity of the Green function for a multiple scattering medium and the notion of scattering-enlarged effective aperture.

  7. ERIS adaptive optics system design

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  8. The ERIS adaptive optics system

    NASA Astrophysics Data System (ADS)

    Marchetti, Enrico; Fedrigo, Enrico; Le Louarn, Miska; Madec, Pierre-Yves; Soenke, Christian; Brast, Roland; Conzelmann, Ralf; Delabre, Bernard; Duchateau, Michel; Frank, Christoph; Klein, Barbara; Amico, Paola; Hubin, Norbert; Esposito, Simone; Antichi, Jacopo; Carbonaro, Luca; Puglisi, Alfio; Quirós-Pacheco, Fernando; Riccardi, Armando; Xompero, Marco

    2014-07-01

    The Enhanced Resolution Imager and Spectrograph (ERIS) is the new Adaptive Optics based instrument for ESO's VLT aiming at replacing NACO and SINFONI to form a single compact facility with AO fed imaging and integral field unit spectroscopic scientific channels. ERIS completes the instrument suite at the VLT adaptive telescope. In particular it is equipped with a versatile AO system that delivers up to 95% Strehl correction in K band for science observations up to 5 micron It comprises high order NGS and LGS correction enabling the observation from exoplanets to distant galaxies with a large sky coverage thanks to the coupling of the LGS WFS with the high sensitivity of its visible WFS and the capability to observe in dust embedded environment thanks to its IR low order WFS. ERIS will be installed at the Cassegrain focus of the VLT unit hosting the Adaptive Optics Facility (AOF). The wavefront correction is provided by the AOF deformable secondary mirror while the Laser Guide Star is provided by one of the four launch units of the 4 Laser Guide Star Facility for the AOF. The overall layout of the ERIS AO system is extremely compact and highly optimized: the SPIFFI spectrograph is fed directly by the Cassegrain focus and both the NIX's (IR imager) and SPIFFI's entrance windows work as visible/infrared dichroics. In this paper we describe the concept of the ERIS AO system in detail, starting from the requirements and going through the estimated performance, the opto-mechanical design and the Real-Time Computer design.

  9. Coated laser mirror and method of coating

    SciTech Connect

    Shuskus, A.J.; Cowher, M.E.

    1984-04-24

    A method of applying an intermediate bond coat on a laser mirror substrate is described comprising surface polishing the mirror substrate followed by depositing a layer of amorphous silicon, amorphous germanium, or mixtures thereof on the mirror surface, and polishing the thus coated mirror surface to a substantially void-free surface finish. Laser mirror substrates such as graphite fiber reinforced glass, molybdenum and silicon carbide coated by such process are also described.

  10. Alignment Mirror Mechanisms for Space Use

    NASA Technical Reports Server (NTRS)

    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.

  11. Test results for an AOA-Xinetics grazing incidence x-ray deformable mirror

    NASA Astrophysics Data System (ADS)

    Lillie, Charles; Egan, Richard; Landers, Franklin; Cavaco, Jeffrey; Ezzo, Kevin; Khounsary, Ali

    2014-09-01

    X-ray telescopes use grazing incidence mirrors to focus X-ray photons from celestial objects. To achieve the large collecting areas required to image faint sources, thousands of thin, doubly curved mirrors are arranged in nested cylindrical shells to approximate a filled aperture. These mirrors require extremely smooth surfaces with precise figures to provide well-focused beams and small image spot sizes. The Generation-X telescope proposed by SAO would have a 12-meter aperture, a 50 m2 collecting area and 0.1 arc-second spatial resolution. This resolution would be obtained by actively controlling the mirror figure with piezoelectric actuators deposited on the back of each 0.4 mm thick mirror segment. To support SAO's Generation-X study, Northrop Grumman used internal funds to look at the feasibility of using Xinetics deformable mirror technologies to meet the Generation-X requirements. We designed and fabricated two 10 x 30 cm Platinum-coated silicon mirrors with 108 surface-parallel electrostrictive Lead Magnesium Niobate (PMN) actuators bonded to the mirror substrates. These mirrors were tested at optical wavelengths by Xinetics to assess the actuator's performance, but no funds were available for X-ray tests. In 2013, after receiving an invitation to evaluate the mirror's performance at Argonne National Laboratory, the mirrors were taken out of storage, refurbished, retested at Xinetics and transported to ANL for metrology measurements with a Long Trace Profilometer, a Fizeau laser interferometer, and X-ray tests. This paper describes the development and testing of the adaptive x-ray mirrors at AOAXinetics. Marathe, et al, will present the results of the tests at Argonne.

  12. Fabrication of nested elliptical KB mirrors using profile coating for synchrotron radiation X-ray focusing

    SciTech Connect

    Liu, Chian; Ice, Gene E; Liu, Wenjun; Assoufid, Lahsen; Qian, J; Shi, B.; Khachatryan, Ruben; Wieczorek, M.; Zschack, P.; Tischler, Jonathan Zachary

    2012-01-01

    This paper describes fabrication methods used to demonstrate the advantages of nested or Montel optics for micro/nanofocusing of synchrotron X-ray beams. A standard Kirkpatrick-Baez (KB) mirror system uses two separated elliptical mirrors at glancing angles to the X-ray beam and sequentially arranged at 90{sup o} to each other to focus X-rays successively in the vertical and horizontal directions. A nested KB mirror system has the two mirrors positioned perpendicular and side-by-side to each other. Compared to a standard KB mirror system, Montel optics can focus a larger divergence and the mirrors can have a shorter focal length. As a result, nested mirrors can be fabricated with improved demagnification factor and ultimately smaller focal spot, than with a standard KB arrangement. The nested system is also more compact with an increased working distance, and is more stable, with reduced complexity of mirror stages. However, although Montel optics is commercially available for laboratory X-ray sources, due to technical difficulties they have not been used to microfocus synchrotron radiation X-rays, where ultra-precise mirror surfaces are essential. The main challenge in adapting nested optics for synchrotron microfocusing is to fabricate mirrors with a precise elliptical surface profile at the very edge where the two mirrors meet and where X-rays scatter. For example, in our application to achieve a sub-micron focus with high efficiency, a surface figure root-mean-square (rms) error on the order of 1 nm is required in the useable area along the X-ray footprint with a {approx} 0.1 mm-diameter cross section. In this paper we describe promising ways to fabricate precise nested KB mirrors using our profile coating technique and inexpensive flat Si substrates.

  13. Soiling and degradation analysis of solar mirrors

    NASA Astrophysics Data System (ADS)

    Delord, Christine; Blaise, Anthony; Fernandez-García, Aránzazu; Martínez-Arcos, Lucía; Sutter, Florian; Reche-Navarro, Tomás Jesús

    2016-05-01

    The degradation and the soiling of the mirrors are dependent of the solar field and the mirrors technologies, the local climate, the meteorological events, the O&M tasks and the human activities around the site. In the frame of the European project SFERA II, the SODAM project has been the opportunity to compare the soiling and the degradation mechanisms on a Fresnel solar field installed in the South of France and on a parabolic-through solar field installed in the South of Spain. The analysis of the soiling has shown equivalent maximum weekly reflectance loss due to soiling in both sites but a double mean weekly reflectance loss in Spain respect to France, as well as typical meteorological events to be taken into account to adapt the cleaning strategies. Among the meteorological parameters mainly influencing the soiling, the study has revealed the effect of the rain and of the DNI. In parallel, the analysis of the degradation mechanisms has highlighted a common chalking of the protective back paint layers due to the irradiation. This chalking being associated to a leaching of the paint layers in the site of Cadarache due to the high presence of liquid water. A difference in the speed of corrosion of the silver layer has been also noticed, leading to a difference in the mechanisms of delamination of the paints layers.

  14. Operation of the adaptive optics system at the Large Binocular Telescope Observatory

    NASA Astrophysics Data System (ADS)

    Miller, Douglas L.; Guerra, Juan Carlos; Boutsia, Konstantina; Fini, Luca; Argomedo, Javier; Biddick, Chris; Agapito, Guido; Arcidiacono, Carmelo; Briguglio, Runa; Brusa, Guido; Busoni, Lorenzo; Esposito, Simone; Hill, John; Kulesa, Craig; McCarthy, Don; Pinna, Enrico; Puglisi, Alfio T.; Quiros-Pacheco, Fernando; Riccardi, Armando; Xompero, Marco

    2012-07-01

    The Adaptive Optics System at the Large Binocular Telescope Observatory consists of two Adaptive Secondary (ASM) mirrors and two Pyramid Wavefront sensors. The first ASM/Pyramid pair has been commissioned and is being used for science operation using the NIR camera PISCES on the right side of the binocular telescope. The left side ASM/Pyramid system is currently being commissioned, with completion scheduled for the Fall of 2012. We will discuss the operation of the first Adaptive Optics System at the LBT Observatory including interactions of the AO system with the telescope and its TCS, observational modes, user interfaces, observational scripting language, time requirement for closed loop and offsets and observing efficiency.

  15. Ultra-lightweight telescope with MEMS adaptive optic for distortion correction.

    SciTech Connect

    Spahn, Olga Blum; Cowan, William D.; Shaw, Michael J.; Adams, David Price; Sweatt, William C.; Dagel, Daryl James; Grine, Alejandro J.; Mani, Seethambal S.; Resnick, Paul James; Gass, Fawn Renee; Grossetete, Grant David

    2004-12-01

    Recent world events have underscored the need for a satellite based persistent global surveillance capability. To be useful, the satellite must be able to continuously monitor objects the size of a person anywhere on the globe and do so at a low cost. One way to satisfy these requirements involves a constellation of satellites in low earth orbit capable of resolving a spot on the order of 20 cm. To reduce cost of deployment, such a system must be dramatically lighter than a traditional satellite surveillance system with a high spatial resolution. The key to meeting this requirement is a lightweight optics system with a deformable primary and secondary mirrors and an adaptive optic subsystem correction of wavefront distortion. This proposal is concerned with development of MEMS micromirrors for correction of aberrations in the primary mirror and improvement of image quality, thus reducing the optical requirements on the deployable mirrors. To meet this challenge, MEMS micromirrors must meet stringent criteria on their performance in terms of flatness, roughness and resolution of position. Using Sandia's SUMMIT foundry which provides the world's most sophisticated surface MEMS technology as well as novel designs optimized by finite element analysis will meet severe requirements on mirror travel range and accuracy.

  16. Hyperbola-parabola primary mirror in Cassegrain optical antenna to improve transmission efficiency.

    PubMed

    Zhang, Li; Chen, Lu; Yang, HuaJun; Jiang, Ping; Mao, Shengqian; Caiyang, Weinan

    2015-08-20

    An optical model with a hyperbola-parabola primary mirror added in the Cassegrain optical antenna, which can effectively improve the transmission efficiency, is proposed in this paper. The optimum parameters of a hyperbola-parabola primary mirror and a secondary mirror for the optical antenna system have been designed and analyzed in detail. The parabola-hyperbola primary structure optical antenna is obtained to improve the transmission efficiency of 10.60% in theory, and the simulation efficiency changed 9.359%. For different deflection angles to the receiving antenna with the emit antenna, the coupling efficiency curve of the optical antenna has been obtained. PMID:26368746

  17. Mirror visual feedback therapy. A practical approach.

    PubMed

    McCabe, Candy

    2011-01-01

    Mirror visual feedback (MVF) was first proposed as a therapy to relieve amputee phantom limb pain in the early 1990s. It is increasingly used to treat a range of other chronic pain conditions. The evidence base to date is limited. Much of the literature consists of pilot projects or case study designs although larger randomized controlled trails are now emerging. However, the described protocols for MVF are inadequate to adapt to clinical practice. In addition, the therapist sees a heterogeneous population whose characteristics may fall outside those of the tight inclusion/exclusion criteria of research studies. This article provides the theoretical background to MVF and a detailed description of applying this therapy in clinical practice. PMID:21106347

  18. Development of testing convex hyperbolic mirror using Hindle method based on stitching technology

    NASA Astrophysics Data System (ADS)

    Jiang, Zi-bo; Li, Xin-nan; Ji, Bo

    2012-09-01

    The test method of Large-diameter convex secondary mirror in development process is the key to making large telescope technology. Classical means HINDLE to test using of non - aberration points needs a spherical reflecting mirror which larger than the secondary mirror several times. This new Hindle test method based on stitching technology can significantly reduce their standard mirror's size, drop the difficulty of processing and cut down the costs. In This paper, the Hindle testing basic principles which base on stitching technology is introduced firstly, then principle of stitching and least square method. Following the parameters of inside and outside standard mirrors are derived. Then translation and rotation transformation algorithm of different sub-aperture interferometer array data is given. Finally the preliminary results of the radial stitching experiments are given. The results showed that the relative error is RMS = 6.1%, PV = 5.11%. With improving and perfection, this method can be used in the E-ELT, CFGT convex secondary mirror telescope test.

  19. Position sensors for segmented mirror

    NASA Astrophysics Data System (ADS)

    Rozière, Didier; Buous, Sébastien; Courteville, Alain

    2004-09-01

    There are currently several projects for giant telescopes with segmented mirrors under way. These future telescopes will have their primary mirror made of several thousand segments. The main advantage of segmentation is that it enables the active control of the whole mirror, so as to suppress the deformations of the support structure due to the wind, gravity, thermal inhomogeneities etc. ..., thus getting the best possible stigmatism. However, providing active control of segmented mirrors requires numerous accurate edges sensors. It is acknowledged that capacitance-based technology nowadays offers the best metrological performances-to-cost ratio. As the leader in capacitive technology, FOGALE nanotech offers an original concept which reduces the cost of instrumentation, sensors and electronics, while keeping a very high level of performances with a manufacturing process completely industrialised. We present here the sensors developed for the Segment Alignment Measurement System (SAMS) of the Southern African Large Telescope (SALT). This patented solution represents an important improvement in terms of cost, to market the Position Sensors for Segmented Mirrors of ELTs, whilst maintaining a very high performance level. We present here the concept, the laboratory qualification, and the first trials on the 7 central segments of SALT. The laboratory results are good, and we are now working on the on-site implementation to improve the immunity of the sensors to environment.

  20. Gasdynamic Multiple-Mirror Trap

    NASA Astrophysics Data System (ADS)

    Beklemishev, Alexei; Anikeev, Andrei; Bagryansky, Peter; Burdakov, Alexander; Gavrilenko, Dmitrii; Ivanov, Alexander; Polosatkin, Sergei; Sinitsky, Stanislav

    2013-10-01

    The new linear device for confinement of fusion plasmas, GDMT, is being developed at the Budker Institute of Nuclear Physics, Novosibirsk. The facility will combine features of existing GOL-3 and GDT devices: the central GDT-like cell with sloshing NBI ions, and the multiple-mirror plugs for suppression of axial losses. Such combination became feasible due to recent discoveries. In particular, the requirement of flute-mode stability can be relaxed by using vortex confinement, achieved by plasma biasing through open field lines. This allows the use of potentially destabilizing multiple-mirror sections. Another key effect is the enhanced multiple-mirror confinement at low densities, which is due to collective rather than coulomb scattering of ions. Hence the multiple-mirror plugs can work at pressures compatible with magnetic confinement. These two main technologies are supplemented by axial injection of pulsed electron beams. Besides additional plasma heating (like in GOL-3), such injection can be used for induced collective scattering in the multiple-mirror plugs and for plasma biasing. The new device is designed to be superconducting and modular. It will be built in stages, with the first stage, GDMT-T, intended for PMI studies. The work was financially supported by Ministry of Education and Science RF.

  1. Wavefront Compensation Segmented Mirror Sensing and Control

    NASA Technical Reports Server (NTRS)

    Redding, David C.; Lou, John Z.; Kissil, Andrew; Bradford, Charles M.; Woody, David; Padin, Stephen

    2012-01-01

    of optical edge sensors are used per segment-to-segment edge, separated by a finite distance along the segment edge, for four optical heads, each with an imager and a collimator. By orienting the beam direction of one edge sensor pair to be +45 away from the segment edge direction, and the other sensor pair to be oriented -45 away from the segment edge direction, all six degrees of freedom of relative motion between the segments can be measured with some redundancy. The software resides in a computer that receives each of the optical edge sensor signals, as well as telescope pointing commands. It feeds back the edge sensor signals to keep the primary mirror figure within specification. It uses a feed-forward control to compensate for global effects such as decollimation of the primary and secondary mirrors due to gravity sag as the telescope pointing changes to track science objects. Three segment position actuators will be provided per segment to enable controlled motions in the piston, tip, and tilt degrees of freedom. These actuators are driven by the software, providing the optical changes needed to keep the telescope phased.

  2. A Novel Concept for a Deformable Membrane Mirror for Correction of Large Amplitude Aberrations

    NASA Technical Reports Server (NTRS)

    Moore, Jim; Patrick, Brian

    2006-01-01

    Very large, light weight mirrors are being developed for applications in space. Due to launch mass and volume restrictions these mirrors will need to be much more flexible than traditional optics. The use of primary mirrors with these characteristics will lead to requirements for adaptive optics capable of correcting wave front errors with large amplitude relatively low spatial frequency aberrations. The use of low modulus membrane mirrors actuated with electrostatic attraction forces is a potential solution for this application. Several different electrostatic membrane mirrors are now available commercially. However, as the dynamic range requirement of the adaptive mirror is increased the separation distance between the membrane and the electrodes must increase to accommodate the required face sheet deformations. The actuation force applied to the mirror decreases inversely proportional to the square of the separation distance; thus for large dynamic ranges the voltage requirement can rapidly increase into the high voltage regime. Experimentation with mirrors operating in the KV range has shown that at the higher voltages a serious problem with electrostatic field cross coupling between actuators can occur. Voltage changes on individual actuators affect the voltage of other actuators making the system very difficult to control. A novel solution has been proposed that combines high voltage electrodes with mechanical actuation to overcome this problem. In this design an array of electrodes are mounted to a backing structure via light weight large dynamic range flextensional actuators. With this design the control input becomes the separation distance between the electrode and the mirror. The voltage on each of the actuators is set to a uniform relatively high voltage, thus the problem of cross talk between actuators is avoided and the favorable distributed load characteristic of electrostatic actuation is retained. Initial testing and modeling of this concept

  3. Compact neutron imaging system using axisymmetric mirrors

    SciTech Connect

    Khaykovich, Boris; Moncton, David E; Gubarev, Mikhail V; Ramsey, Brian D; Engelhaupt, Darell E

    2014-05-27

    A dispersed release of neutrons is generated from a source. A portion of this dispersed neutron release is reflected by surfaces of a plurality of nested, axisymmetric mirrors in at least an inner mirror layer and an outer mirror layer, wherein the neutrons reflected by the inner mirror layer are incident on at least one mirror surface of the inner mirror layer N times, wherein N is an integer, and wherein neutrons reflected by the outer mirror are incident on a plurality of mirror surfaces of the outer layer N+i times, where i is a positive integer, to redirect the neutrons toward a target. The mirrors can be formed by a periodically reversed pulsed-plating process.

  4. Metrology of IXO Mirror Segments

    NASA Technical Reports Server (NTRS)

    Chan, Kai-Wing

    2011-01-01

    For future x-ray astrophysics mission that demands optics with large throughput and excellent angular resolution, many telescope concepts build around assembling thin mirror segments in a Wolter I geometry, such as that originally proposed for the International X-ray Observatory. The arc-second resolution requirement posts unique challenges not just for fabrication, mounting but also for metrology of these mirror segments. In this paper, we shall discuss the metrology of these segments using normal incidence metrological method with interferometers and null lenses. We present results of the calibration of the metrology systems we are currently using, discuss their accuracy and address the precision in measuring near-cylindrical mirror segments and the stability of the measurements.

  5. Alpha Channeling in Mirror Machines

    SciTech Connect

    Fisch N.J.

    2005-10-19

    Because of their engineering simplicity, high-β, and steady-state operation, mirror machines and related open-trap machines such as gas dynamic traps, are an attractive concept for achieving controlled nuclear fusion. In these open-trap machines, the confinement occurs by means of magnetic mirroring, without the magnetic field lines closing upon themselves within the region of particle confinement. Unfortunately, these concepts have not achieved to date very spectacular laboratory results, and their reactor prospects are dimmed by the prospect of a low Q-factor, the ratio of fusion power produced to auxiliary power. Nonetheless, because of its engineering promise, over the years numerous improvements have been proposed to enhance the reactor prospects of mirror fusion, such as tandem designs, end-plugging, and electric potential barriers.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Fokker-Planck equation in mirror research

    SciTech Connect

    Post, R.F.

    1983-08-11

    Open confinement systems based on the magnetic mirror principle depend on the maintenance of particle distributions that may deviate substantially from Maxwellian distributions. Mirror research has therefore from the beginning relied on theoretical predictions of non-equilibrium rate processes obtained from solutions to the Fokker-Planck equation. The F-P equation plays three roles: Design of experiments, creation of classical standards against which to compare experiment, and predictions concerning mirror based fusion power systems. Analytical and computational approaches to solving the F-P equation for mirror systems will be reviewed, together with results and examples that apply to specific mirror systems, such as the tandem mirror.

  8. Fused silica mirror development for SIRTF

    NASA Technical Reports Server (NTRS)

    Barnes, W. P., Jr.

    1983-01-01

    An advanced design, lightweight, fuse-quartz mirror of sandwich construction was evaluated for optical figure performance at cryogenic temperatures. A low temperature shroud was constructed with an integral mirror mount and interface to a cryostat for use in a vacuum chamber. The mirror was tested to 13 K. Cryogenic distortion of the mirror was measured interferometrically. Separate interferometry of the chamber window during the test permitted subtraction of the small window distortions from the data. Results indicate that the imaging performance of helium cooled, infrared telescopes will be improved using this type of mirror without correction of cryogenic distortion of the primary mirror.

  9. Pre-construction of giant steerable science mirror for TMT

    NASA Astrophysics Data System (ADS)

    Yang, Fei; Zhao, Hongchao; Guo, Peng; An, Qichang; Jiang, Haibo

    2015-09-01

    The Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) team is developing the Giant Steerable Science Mirror (GSSM) for Thirty Meter Telescope (TMT) which will get into the preliminary design phase in 2016. To develop the passive support structure system for the largest elliptic-plan flat mirror and smoothest tracking mechanism for the gravity-invariant condition, CIOMP is designing and building a 1/4 scale, functionally accurate version of the GSSM prototype. The prototype will incorporate the same optical-mechanical system and electric control system as the GSSM. The size of the prototype mirror is 898.5mm×634mm×12.5mm with elliptic-plan figure and will be supported by 18 points whiffletree on axial and 12 points whiffletree on lateral. The mirror surface figure will be evaluated by SlopeRMS which is the final evaluation method used in the actual GSSM. The prototype allows the mirror point to and be tested in five specified gravity orientations and meet the requirements of SlopeRMS. The prototype testing platform will have the interfaces with direct drive systems. The jitter testing will be implemented on the prototype system to verify the bearing, the encoder, the servo control algorithm in the low speed up to 5 arcsecond per second. The total prototype system configured mirror surface figure will be better than 1 micro radian SlopeRMS in each tested orientation. The positioner jitter will be less than 0.1 arcsecond RMS for tilt and rotator axis respectively and will be analyzed with frequency domain to meet the requirements of the TMT adaptive optics system. The pre-construction will be completed at the beginning of 2016 and provide the technical support to the preliminary design of GSSM.

  10. High temperature current mirror amplifier

    DOEpatents

    Patterson, R.B. III.

    1984-05-22

    Disclosed is a high temperature current mirror amplifier having biasing means in the transdiode connection of the input transistor for producing a voltage to maintain the base-collector junction reversed-biased and a current means for maintaining a current through the biasing means at high temperatures so that the base-collector junction of the input transistor remained reversed-biased. For accuracy, a second current mirror is provided with a biasing means and current means on the input leg. 2 figs.

  11. Microwave Tomography Using Deformable Mirrors

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

    Microwave tomography aims to reconstruct the spatial distribution of the electrical property of penetrable objects using field measurements acquired from multiple views at single or multiple frequencies. This paper presents a novel microwave tomography technique to image penetrable scatterers using deformable mirrors. The deformable mirror consists of a continuum of radiating elements that yields multi-view field measurements for noninvasive characterization of the spatial dielectric property of the scatterer in the microwave regime. Computational feasibility of the proposed technique is presented for heterogeneous two dimensional dielectric scatterers.

  12. Silicon cladding for mirror substrates

    NASA Astrophysics Data System (ADS)

    Duston, Christopher J.; Gunda, Nilesh; Schwartz, Jay R.; Robichaud, Joseph L.

    2009-08-01

    To reduce the finishing costs of silicon carbide mirror substrates, silicon claddings are applied allowing the surfaces to be more easily diamond turned and polished than the bare chemical vapor deposited (CVD) silicon carbide or bimodal reaction bonded SiC (RB-SiC). The benefits of using silicon as the optical face will be reviewed as will the process for applying plasma enhanced chemical vapor (PE-CVD) deposited amorphous silicon cladding on substrates. Using one mirror as an example, the successful finishing results will be shared.

  13. Controllable objective with deformable mirrors

    SciTech Connect

    Agafonov, V V; Safronov, A G

    2004-03-31

    A new optical device - an objective with deformable mirrors and parameters controlled in the dynamic regime is proposed. The computer simulation of the objective is performed. The dependences of some parameters of the objective on the control voltage are determined. The simulation showed that the ranges of control of the rear focal segment and the focal distance for the objective with the focal distance 602 mm were 1057 and 340 mm, respectively, which is substantially greater than in the control of an equivalent deformable mirror. (laser applications and other topics in quantum electronics)

  14. Compaction managed mirror bend achromat

    DOEpatents

    Douglas, David

    2005-10-18

    A method for controlling the momentum compaction in a beam of charged particles. The method includes a compaction-managed mirror bend achromat (CMMBA) that provides a beamline design that retains the large momentum acceptance of a conventional mirror bend achromat. The CMMBA also provides the ability to tailor the system momentum compaction spectrum as desired for specific applications. The CMMBA enables magnetostatic management of the longitudinal phase space in Energy Recovery Linacs (ERLs) thereby alleviating the need for harmonic linearization of the RF waveform.

  15. NASA CONNECT: Algebra: Mirror, Mirror on the Universe

    NASA Technical Reports Server (NTRS)

    2000-01-01

    'Algebra: Mirror, Mirror on the Universe' is the last of seven programs in the 1999-2000 NASA CONNECT series. Produced by NASA Langley Research Center's Office of Education, NASA CONNECT is an award-winning series of instructional programs designed to enhance the teaching of math, science and technology concepts in grades 5-8. NASA CONNECT establishes the 'connection' between the mathematics, science, and technology concepts taught in the classroom and NASA research. Each program in the series supports the national mathematics, science, and technology standards; includes a resource-rich teacher guide; and uses a classroom experiment and web-based activity to complement and enhance the math, science, and technology concepts presented in the program. NASA CONNECT is FREE and the programs in the series are in the public domain. Visit our web site and register. http://connect.larc.nasa.gov In 'Algebra: Mirror, Mirror on the Universe', students will learn how algebra is used to explore the universe.

  16. Timecourse of mirror and counter-mirror effects measured with transcranial magnetic stimulation

    PubMed Central

    Cavallo, Andrea; Heyes, Cecilia; Becchio, Cristina; Bird, Geoffrey

    2014-01-01

    The human mirror system has been the subject of much research over the past two decades, but little is known about the timecourse of mirror responses. In addition, it is unclear whether mirror and counter-mirror effects follow the same timecourse. We used single-pulse transcranial magnetic stimulation to investigate the timecourse of mirror and counter-mirror responses in the human brain. Experiment 1 demonstrated that mirror responses can be measured from around 200 ms after observed action onset. Experiment 2 demonstrated significant effects of counter-mirror sensorimotor training at all timepoints at which a mirror response was found in Experiment 1 (i.e. from 200 ms onward), indicating that mirror and counter-mirror responses follow the same timecourse. By suggesting similarly direct routes for mirror and counter-mirror responses, these results support the associative account of mirror neuron origins whereby mirror responses arise as a result of correlated sensorimotor experience during development. More generally, they contribute to theorizing regarding mirror neuron function by providing some constraints on how quickly mirror responses can influence social cognition. PMID:23709352

  17. Timecourse of mirror and counter-mirror effects measured with transcranial magnetic stimulation.

    PubMed

    Cavallo, Andrea; Heyes, Cecilia; Becchio, Cristina; Bird, Geoffrey; Catmur, Caroline

    2014-08-01

    The human mirror system has been the subject of much research over the past two decades, but little is known about the timecourse of mirror responses. In addition, it is unclear whether mirror and counter-mirror effects follow the same timecourse. We used single-pulse transcranial magnetic stimulation to investigate the timecourse of mirror and counter-mirror responses in the human brain. Experiment 1 demonstrated that mirror responses can be measured from around 200 ms after observed action onset. Experiment 2 demonstrated significant effects of counter-mirror sensorimotor training at all timepoints at which a mirror response was found in Experiment 1 (i.e. from 200 ms onward), indicating that mirror and counter-mirror responses follow the same timecourse. By suggesting similarly direct routes for mirror and counter-mirror responses, these results support the associative account of mirror neuron origins whereby mirror responses arise as a result of correlated sensorimotor experience during development. More generally, they contribute to theorizing regarding mirror neuron function by providing some constraints on how quickly mirror responses can influence social cognition. PMID:23709352

  18. Development of large aperture composite adaptive optics

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  19. Alignment and Integration Techniques for Mirror Segment Pairs on the Constellation X Telescope

    NASA Technical Reports Server (NTRS)

    Hadjimichael, Theo; Lehan, John; Olsen, Larry; Owens, Scott; Saha, Timo; Wallace, Tom; Zhang, Will

    2007-01-01

    We present the concepts behind current alignment and integration techniques for testing a Constellation-X primary-secondary mirror segment pair in an x-ray beam line test. We examine the effects of a passive mount on thin glass x-ray mirror segments, and the issues of mount shape and environment on alignment. We also investigate how bonding and transfer to a permanent housing affects the quality of the final image, comparing predicted results to a full x-ray test on a primary secondary pair.

  20. Design of a grating spectrometer from a 1:1 Offner mirror system

    NASA Technical Reports Server (NTRS)

    Kwo, Deborah; Lawrence, George; Chrisp, Michael

    1987-01-01

    A 1:1 Offner mirror system is modified to work as a grating spectrometer for the infrared by placing a grating on the secondary convex mirror of the system. Slight adjustment of the configuration combined with tilt of the secondary provide the necessary degrees of freedom to correct for astigmatism of the system. Additional control may be obtained by using a holographic optical element (HOE), constructed to add necessary compensating aberrations. Details of the best configuration and the limitations of performance are presented.

  1. Collodion technique of mirror cleaning

    NASA Technical Reports Server (NTRS)

    Tyndall, J. B.

    1970-01-01

    Cleaning method is modified by addition of a layer of cheesecloth between thin coatings of U.S.P. collodion. After drying, the collodion is peeled off by an even pull on the cheesecloth, leaving the mirror clean and ready for use.

  2. RF plugging of mirror plasma

    SciTech Connect

    Kotelnikov, I.A.; Kuzmin, S.G.

    1996-12-01

    Discovery of superconducting materials that operate at high temperatures revives interest in the use of rf field for plasma confinement. This paper discusses feasibility of a scheme where resonant rf cavities are attached to the mirror ends of an open system for plasma confinement. 9 refs., 9 figs.

  3. Mirror Confinement Systems: project summaries

    SciTech Connect

    Not Available

    1980-07-01

    This report contains descriptions of the projects supported by the Mirror Confinement Systems (MCS) Division of the Office of Fusion Energy. The individual project summaries were prepared by the principal investigators, in collaboration with MCS staff office, and include objectives and milestones for each project. In addition to project summaries, statements of Division objectives and budget summaries are also provided.

  4. Microfabricated mirrors for space applications

    NASA Astrophysics Data System (ADS)

    Bayat, Dara; Ataman, Caglar; Guldimann, Benedikt; Lani, Sébastien; Noell, Wilfried; de Rooij, Nico

    2011-03-01

    We report on the advances towards the design and fabrication of a system consisting of two 10mm mirrors, one actuated magnetically and the other electrostatically. The system will be used for beam steering. The maximum resonant frequencies and deflection angle of each of the actuators will be reviewed and compared.

  5. Mirror with thermally controlled radius of curvature

    DOEpatents

    Neil, George R.; Shinn, Michelle D.

    2010-06-22

    A radius of curvature controlled mirror for controlling precisely the focal point of a laser beam or other light beam. The radius of curvature controlled mirror provides nearly spherical distortion of the mirror in response to differential expansion between the front and rear surfaces of the mirror. The radius of curvature controlled mirror compensates for changes in other optical components due to heating or other physical changes. The radius of curvature controlled mirror includes an arrangement for adjusting the temperature of the front surface and separately adjusting the temperature of the rear surface to control the radius of curvature. The temperature adjustment arrangements can include cooling channels within the mirror body or convection of a gas upon the surface of the mirror. A control system controls the differential expansion between the front and rear surfaces to achieve the desired radius of curvature.

  6. Alignment of two mirror astronomical telescopes (the astigmatic component)

    NASA Astrophysics Data System (ADS)

    Schmid, Tobias; Thompson, Kevin; Rolland, Jannick

    2008-07-01

    The effects of alignment perturbations on the aberration fields of two mirror astronomical telescopes are discussed. It is demonstrated that expressions describing alignment induced field-linear astigmatism, published by McLeod based on the work of Schroeder, can be obtained using nodal aberration theory. Rather than merely providing a different derivation for alignment induced astigmatism, it is shown that nodal theory can provide several insights that are significant for the development of effective alignment techniques. In the example of a specific telescope sited on Mt. Hopkins (Ritchey- Chretien), two approaches to identify misalignments of the secondary mirror are demonstrated. One approach utilizes the eccentricity of defocused star images and their orientation angles to calculate the misalignment of the secondary mirror after axial coma is removed. A second approach based on the location of the two zeros of the astigmatic aberration field is then shown to give equivalent results, but at the same time ensuring a complete model of all possible effects of misalignment on the performance of the telescope.

  7. HIGH-CONTRAST IMAGING VIA MODAL CONVERGENCE OF DEFORMABLE MIRROR

    SciTech Connect

    Wang Feiling

    2012-06-01

    For extremely high contrast imaging, such as direct observation of faint stellar companions, an adaptive optics system is required to produce low-halo and low-speckle regions in the focal plane. A method for deformable mirror control is proposed to achieve this goal. The method relies on a modal convergence of the deformable mirror driven by a focal-plane metric. The modal sets are derived from the Walsh functions. The Walsh-function modes serve two purposes: the expansion of the actuator displacements and the expansion of the phase functions. Taking advantage of the unique properties of the modal functions, a universal control algorithm is devised for the realization of high-contrast focal planes with and without the help of conventional coronagraphy. Numerical modeling is conducted to simulate complete imaging systems under various scenarios. It is shown that the proposed method reliably produces high-contrast focal planes using either a segmented or a membrane mirror. In the presence of random aberration the method is shown to be able to maintain high-contrast focal planes. Requiring neither retrieval of electric fields nor detailed knowledge of the deformable mirrors, this technique may allow high-contrast imaging in real time.

  8. Secrets of the Chinese magic mirror replica

    NASA Astrophysics Data System (ADS)

    Mak, Se-yuen; Yip, Din-yan

    2001-03-01

    We examine the structure of five Chinese magic mirror replicas using a special imaging technique developed by the authors. All mirrors are found to have a two-layered structure. The reflecting surface that gives rise to a projected magic pattern on the screen is hidden under a polished half-reflecting top layer. An alternative method of making the magic mirror using ancient technology has been proposed. Finally, we suggest a simple method of reconstructing a mirror replica in the laboratory.

  9. Mounting and Alignment of IXO Mirror Segments

    NASA Technical Reports Server (NTRS)

    Chan, Kai-Wing; Zhang, William; Evans, Tyler; McClelland, Ryan; Hong, Melinda; Mazzarella, James; Saha, Timo; Jalota, Lalit; Olsen, Lawrence; Byron, Glenn

    2010-01-01

    A suspension-mounting scheme is developed for the IXO (International X-ray Observatory) mirror segments in which the figure of the mirror segment is preserved in each stage of mounting. The mirror, first fixed on a thermally compatible strongback, is subsequently transported, aligned and transferred onto its mirror housing. In this paper, we shall outline the requirement, approaches, and recent progress of the suspension mount processes.

  10. Detecting surface faults on solar mirrors

    NASA Technical Reports Server (NTRS)

    Argoud, M. J.; Shumate, M. S.; Walker, W. L.; Zanteson, R. A.

    1980-01-01

    Two quality control tests determine reflectivity and curvature faults of concave solar mirrors. Curvature defects in solar mirrors are easily revealed by photographing mirror surface. Calibrated aperture placed in front of camera lens admits rays reflecting only from acceptable areas of mirror, blocking out diverging rays reflected from defective areas. Defects can pinpoint problems that may exist in production. Same photograph can be obtained using calibrated disk instead of aperture, except that, this time, only defective areas would be exposed.

  11. The Axisymmetric Tandem Mirror: A Magnetic Mirror Concept Game Changer Magnet Mirror Status Study Group

    SciTech Connect

    Simonen, T; Cohen, R; Correll, D; Fowler, K; Post, D; Berk, H; Horton, W; Hooper, E B; Fisch, N; Hassam, A; Baldwin, D; Pearlstein, D; Logan, G; Turner, B; Moir, R; Molvik, A; Ryutov, D; Ivanov, A A; Kesner, J; Cohen, B; McLean, H; Tamano, T; Tang, X Z; Imai, T

    2008-10-24

    Experimental results, theory and innovative ideas now point with increased confidence to the possibility of a Gas Dynamic Trap (GDT) neutron source which would be on the path to an attractively simple Axisymmetric Tandem Mirror (ATM) power plant. Although magnetic mirror research was terminated in the US 20 years ago, experiments continued in Japan (Gamma 10) and Russia (GDT), with a very small US effort. This research has now yielded data, increased understanding, and generated ideas resulting in the new concepts described here. Early mirror research was carried out with circular axisymmetric magnets. These plasmas were MHD unstable due to the unfavorable magnetic curvature near the mid-plane. Then the minimum-B concept emerged in which the field line curvature was everywhere favorable and the plasma was situated in a MHD stable magnetic well (70% average beta in 2XII-B). The Ioffe-bar or baseball-coil became the standard for over 40 years. In the 1980's, driven by success with minimum-B stabilization and the control of ion cyclotron instabilities in PR6 and 2XII-B, mirrors were viewed as a potentially attractive concept with near-term advantages as a lower Q neutron source for applications such as a hybrid fission fuel factory or toxic waste burner. However there are down sides to the minimum-B geometry: coil construction is complex; restraining magnetic forces limit field strength and mirror ratios. Furthermore, the magnetic field lines have geodesic curvature which introduces resonant and neoclassical radial transport as observed in early tandem mirror experiments. So what now leads us to think that simple axisymmetric mirror plasmas can be stable? The Russian GDT experiment achieves on-axis 60% beta by peaking of the kinetic plasma pressure near the mirror throat (where the curvature is favorable) to counter-balance the average unfavorable mid-plane curvature. Then a modest augmentation of plasma pressure in the expander results in stability. The GDT

  12. Telescope Adaptive Optics Code

    SciTech Connect

    Phillion, D.

    2005-07-28

    The Telescope AO Code has general adaptive optics capabilities plus specialized models for three telescopes with either adaptive optics or active optics systems. It has the capability to generate either single-layer or distributed Kolmogorov turbulence phase screens using the FFT. Missing low order spatial frequencies are added using the Karhunen-Loeve expansion. The phase structure curve is extremely dose to the theoreUcal. Secondly, it has the capability to simulate an adaptive optics control systems. The default parameters are those of the Keck II adaptive optics system. Thirdly, it has a general wave optics capability to model the science camera halo due to scintillation from atmospheric turbulence and the telescope optics. Although this capability was implemented for the Gemini telescopes, the only default parameter specific to the Gemini telescopes is the primary mirror diameter. Finally, it has a model for the LSST active optics alignment strategy. This last model is highly specific to the LSST

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

    NASA Astrophysics Data System (ADS)

    Piatrou, Piotr

    2014-08-01

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

  14. 21 CFR 886.1500 - Headband mirror.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Headband mirror. 886.1500 Section 886.1500 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1500 Headband mirror. (a) Identification. A headband mirror is a device intended to be strapped to the head of the user to reflect light for use...

  15. 21 CFR 886.1500 - Headband mirror.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Headband mirror. 886.1500 Section 886.1500 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1500 Headband mirror. (a) Identification. A headband mirror is a device intended to be strapped to the head of the user to reflect light for use...

  16. Light Weight Silicon Mirrors for Space Instrumentation

    NASA Technical Reports Server (NTRS)

    Bly, Vincent T.; Hill, Peter C.; Hagopian, John G.; Strojay, Carl R.; Miller, Timothy

    2012-01-01

    Each mirror is a monolithic structure from a single crystal of silicon. The mirrors are light weighted after the optical surface is ground and polished. Mirrors made during the initial phase of this work were typically 1/50 lambda or better (RMS at 633 n m)

  17. Tandem mirror next step conceptual design

    SciTech Connect

    Doggett, J.N.; Damm, C.C.; Bulmer, R.H.

    1980-10-14

    A study was made to define the features of the experimental mirror fusion device - The Tandem Mirror Next Step, or TMNS - that will bridge the gap between present mirror confinement experiments and a power-producing reactor. We outline the project goals, describe some initial device parameters, and relate the technological requirements to ongoing development programs.

  18. Teaching Secondary School Biology for Social Relevance.

    ERIC Educational Resources Information Center

    Meyer, G. Rex; And Others

    Since the 1960's biology teaching in secondary schools has been transformed from a formal approach reflecting the structure of the discipline and mirroring the concerns of the scientific community to a broad-based approach reflecting the concerns of society as a whole. The aim of biology education today is to heighten awareness, improve students'…

  19. Secondary parkinsonism

    MedlinePlus

    Parkinsonism - secondary; Atypical Parkinson disease ... to be less responsive to medical therapy than Parkinson disease. ... Unlike Parkinson disease, some types of secondary parkinsonism may stabilize or even improve if the underlying cause is treated. ...

  20. Secondary parkinsonism

    MedlinePlus

    Parkinsonism - secondary; Atypical Parkinson disease ... to be less responsive to medical therapy than Parkinson disease. ... Unlike Parkinson disease, some types of secondary parkinsonism may stabilize or even improve if the underlying cause is treated. Brain ...

  1. Axial Electron Heat Loss From Mirror Devices Revisited

    SciTech Connect

    Ryutov, D

    2004-08-16

    An issue of the axial electron heat loss is of a significant importance for mirror-based fusion devices. This problem has been considered in a number of publications but it is still shrouded in misconceptions. In this paper we revisit it once again. We discuss the following issues: (1) Formation of the electron distribution function in the end tank at large expansion ratios; (2) The secondary emission from the end plates and the ways of suppressing it (if needed); (3) Ionization and charge exchange in the presence of neutrals in the end tanks; (4) Instabilities caused by the peculiar shape of the electron distribution function and their possible impact on the electron heat losses; (5) Electron heat losses in the pulsed mode of operation of mirror devices.

  2. Control of a woofer tweeter system of deformable mirrors

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

    This paper describes the control of two deformable mirrors (DM) and a tip tilt mirror for adaptive optics. The purpose of this experimental adaptive optics system at the University of Victoria is to prove the Woofer Tweeter concept for use in instruments for the Thirty Meter Telescope (TMT) which is currently under development. The first deformable mirror is a large stroke DM (Woofer) capable of lower frequency correction in both the temporal and spatial domains. The other DM (Tweeter) is capable of the high temporal and spatial frequency corrections of the turbulence. The response speed of the Woofer is incorporated into the Tweeter controller in order to allow for appropriate offloading from the Tweeter to the Woofer. In order to determine which Tweeter shapes must compensate for the slower Woofer and which are not coupled to the Woofer, the cross correlation of the devices is determined. The method of converting the wave front sensor (WFS) measurements to control signal error is given. The transfer functions of the controller are provided, along with rejection ratio plots, bandwidths and amplitude response to system noise.

  3. Deformable mirrors: design fundamentals for force actuation of continuous facesheets

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

    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 (< 10mm) and a high control bandwidth (> 100Hz). The availability of piezoelectric ceramics as an actuator principle has driven the development of many adaptive deformable mirrors towards inappropriately stiff displacement actuation. This, while the use of force actuation supersedes piezos in performance and longevity while being less costly per channel by a factor of 10-20. This paper presents a model which is independent of the actuator type used for actuation of continuous facesheet deformable mirrors, to study the design parameters such as: actuator spacing & coupling, influence function, peak-valley stroke, dynamical behavior: global & local, etc. The model is validated using finite element simulations and its parameters are used to derive design fundamentals for optimization.

  4. The ESO Adaptive Optics Facility under Test

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  5. TRL-6 Qualification of JWST Mirror Segments

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip

    2009-01-01

    Since 1996, all key mirror technology for a JWST Primary Mirror Segment Assembly (PMSA), as defined directly from the JWST Level 1 Science Requirements, have been developed and matured from a Technology Readiness Level (TRL) of 3 to 6. This has occurred as the result of a highly successful technology development program including sub-scale Beryllium Mirror Demonstrator (SBMD), Advanced Mirror System Demonstrator (AMSD), and JWST flight mirror fabrication. Directly traceable prototypes (and in some cases the flight hardware itself) has been built, tested and operated in a relevant environment.

  6. Actuator usage and fault tolerance of the James Webb Space Telescope optical element mirror actuators

    NASA Astrophysics Data System (ADS)

    Barto, A.; Acton, D. S.; Finley, P.; Gallagher, B.; Hardy, B.; Knight, J. S.; Lightsey, P.

    2012-09-01

    The James Webb Space Telescope (JWST) telescope's secondary mirror and eighteen primary mirror segments are each actively controlled in rigid body position via six hexapod actuators. The mirrors are stowed to the mirror support structure to survive the launch environment and then must be deployed 12.5 mm to reach the nominally deployed position before the Wavefront Sensing & Control (WFS&C) alignment and phasing process begins. The actuation system is electrically, but not mechanically redundant. Therefore, with the large number of hexapod actuators, the fault tolerance of the OTE architecture and WFS&C alignment process has been carefully considered. The details of the fault tolerance will be discussed, including motor life budgeting, failure signatures, and motor life.

  7. A twin-mirrored galvanometer laser light sheet generator

    NASA Technical Reports Server (NTRS)

    Rhodes, David B.; Franke, John M.; Jones, Stephen B.; Leighty, Bradley D.

    1988-01-01

    A galvanometer mirror-based laser light sheet system has been developed for use in the Basic Aerodynamics Research Tunnel at NASA Langley. This system generates and positions single or multiple light sheets over aeronautical research models being tested in the low speed tunnel. This report describes a twin mirrored galvanometer laser light sheet generator and shows typical light sheet arrangements in use. With this system, illumination of smoke entrained in the flow over a delta wing model reveals the vortical flow produced by the separation of the flow at the leading edge of the model. The light sheet system has proven to be very adaptable and easy to use in sizing and positioning light sheets in wind tunnel applications.

  8. Two-mirrored galvanometer laser light sheet generator

    NASA Technical Reports Server (NTRS)

    Leighty, B. D.; Franke, J. M.; Jones, S. B.; Rhodes, D. B.

    1988-01-01

    Light sheets generated with either laser or noncoherent sources have found widespread application to flow visualization. Previous light sheet generating systems were usually dedicated to a specific viewing geometry. The technique with the most flexibility is the galvanometer mirror based laser light sheet system. A two-mirrored system was designed and developed to provide flexibility and adaptability to a wide range of applications. The design includes the capability to control the size and location of the laser light sheet in real time, to generate horizontal or vertical sheets, to sweep the sheet repeatedly through a volume, to generate multiple sheets with controllable separation and to rotate single or multiple laser light sheets. The system is capable of producing up to 12 sheets of laser light at an angular divergence of + or - 20 degrees. Maximum scan rate of any one line is 500 Hertz. This system has proven to be uniquely versatile and a patent has been applied for.

  9. Flextensional Single Crystal Piezoelectric Actuators for Membrane Deformable Mirrors

    NASA Technical Reports Server (NTRS)

    Jiang, Xiaoning; Sahul, Raffi; Hackenberger, Wesley S.

    2006-01-01

    Large aperture and light weight space telescopes requires adaptive optics with deformable mirrors capable of large amplitude aberration corrections at a broad temperature range for space applications including NASA missions such as SAFIR, TPF, Con-X, etc. The single crystal piezoelectric actuators produced at TRS offer large stroke, low hysteresis, and an excellent cryogenic strain response. Specifically, the recently developed low profile, low voltage flextensional single crystal piezoelectric actuators with dimensions of 18 x 5 x 1 mm showed stroke larger than 95 microns under 300 V. Furthermore, flextensional actuator retained approx. 40-50% of its room temperature strain at liquid Nitrogen environment. In this paper, ATILA FEM design of flextensional actuators, actuator fabrication, and characterization results will be presented for the future work on membrane deformable mirror.

  10. JWST Lightweight Mirror TRL-6 Results

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip

    2007-01-01

    Mirror technology for a Primary Mirror Segment Assembly (PMSA) is a system of components: reflective coating; polished optical surface; mirror substrate; actuators, mechanisms and flexures; and reaction structure. The functional purpose of a PMSA is to survive launch, deploy and align itself to form a 25 square meter collecting area 6.5 meter diameter primary mirror with a 131 nm rms wavefront error at temperatures less than 50K and provide stable optical performance for the anticipated thermal environment. At the inception of JWST in 1996, such a capability was at a Technology Readiness Level (TRL) of 3. A highly successful technology development program was initiated including the Sub-scale Beryllium Mirror Demonstrator (SBMD) and Advanced Mirror System Demonstrator (AMSD) projects. These projects along with flight program activities have matured mirror technology for JWST to TRL-6. A directly traceable prototype (and in some cases the flight hardware itself) has been built, tested and operated in a relevant environment.

  11. Constellation-X mirror technology development

    NASA Astrophysics Data System (ADS)

    Zhang, W. W.; Bolognese, J.; Byron, G.; Chang, K. W.; Content, D. A.; Hadjimichael, T. J.; He, Charles; Hill, M. D.; Hong, M.; Lehan, J. P.; Lozipone, L.; Mazzarella, J. M.; McClelland, R.; Nguyen, D. T.; Olsen, L.; Petre, R.; Robinson, D.; Rohrbach, S. O.; Russell, R.; Saha, T. T.; Sharpe, M.; Gubarev, M. V.; Jones, W. D.; O'Dell, S. L.; Davis, W.; Caldwell, D. R.; Freeman, M.; Podgorski, W.; Reid, P. B.

    2008-07-01

    As NASA's next major space X-ray observatory, the Constellation-X mission (Bookbinder et al. 2008) requires mirror assemblies with unprecedented characteristics that cannot be provided by existing optical technologies. In the past several years, the project has supported a vigorous mirror technology development program. This program includes the fabrication of lightweight mirror segments by slumping commercially available thin glass sheets, the support and mounting of these thin mirror segments for accurate metrology, the mounting and attachment of these mirror segments for the purpose of X-ray tests, and development of methods for aligning and integrating these mirror segments into mirror assemblies. This paper describes our efforts and developments in these areas.

  12. Design of a rapidly cooled cryogenic mirror

    NASA Astrophysics Data System (ADS)

    Plummer, Ron; Hsu, Ike

    1993-01-01

    The paper discusses the design, analysis, and testing of a rapidly cooled beryllium cryogenic mirror, which is the primary mirror in the four-element optical system for the Long Wavelength Infrared Advanced Technology Seeker. The mirror is shown to meet the requirement of five minutes for cooling to cryogenic operating temperature; it also maintains its optical figure and vacuum integrity and meets the nuclear specification. Results of a detailed thermal analysis on the mirror showed that, using nitrogen gas at 80 K as coolant, the front face of the mirror can be cooled from an initial temperature of 300 K to less than 90 K within five minutes. In a vacuum chamber, using liquid nitrogen as coolant, the mirror can be cooled to 80 K within 1.5 min. The mirror is well thermally insulated, so that it can be maintained at less than its operating temperature for a long time without active cooling.

  13. A Deployable Primary Mirror for Space Telescopes

    NASA Technical Reports Server (NTRS)

    Lake, Mark S.; Phelps, James E.; Dyer, Jack E.; Caudle, David A.; Tam, Anthony; Escobedo, Javier; Kasl, Eldon P.

    1999-01-01

    NASA Langley Research Center, Composite Optics, Inc., and Nyma/ADF have developed jointly a deployable primary mirror for space telescopes that combines over five years of research on deployment of optical-precision structures and over ten years of development of fabrication techniques for optical-precision composite mirror panels and structures. The deployable mirror is directly applicable to a broad class of non-imaging "lidar" (light direction and ranging) telescopes whose figure-error requirements are in the range of one to ten microns RMS. Furthermore, the mirror design can be readily modified to accommodate imaging-quality reflector panels and active panel-alignment control mechanisms for application to imaging telescopes. The present paper: 1) describes the deployable mirror concept; 2) explains the status of the mirror development; and 3) provides some technical specifications for a 2.55-m-diameter, proof-of-concept mirror.

  14. Radius of curvature controlled mirror

    DOEpatents

    Neil, George R.; Rathke, John Wickham; Schultheiss, Thomas John; Shinn, Michelle D.; Dillon-Townes, Lawrence A.

    2006-01-17

    A controlled radius of curvature mirror assembly comprising: a distortable mirror having a reflective surface and a rear surface; and in descending order from the rear surface; a counter-distortion plate; a flow diverter having a flow diverter aperture at the center thereof; a flow return plate having a flow return aperture at the center thereof; a thermal isolation plate having a thermal isolation plate aperture at the center thereof and a flexible heater having a rear surface and a flexible heater aperture at the center thereof; a double walled tube defining a coolant feed chamber and a coolant return chamber; said coolant feed chamber extending to and through the flow diverter aperture and terminating at the counter-distortion plate and the coolant return chamber extending to and through the thermal isolation backplate and terminating at the flow diverter; and a coolant feed and a coolant return exit at the rear of said flexible heater.

  15. Oculometer focus and mirror control

    NASA Technical Reports Server (NTRS)

    Guy, W. J.

    1982-01-01

    An automatic focusing system designed around an ultrasonic range measurement is described. Besides maintaining the focus, subject distance is a by-product which could lighten the NOVA computational effort. An automatic head tracking unit is also discussed. It is intended to reduce the search time required when track is lost. An X-Y ultrasonic measurement is also made in this design to control the deflection mirrors.

  16. Nine toes; Mirror Foot Deformity

    PubMed Central

    Vlahovic, Aleksandar M; Pistignjat, Boris S; Vlahovic, Natasa S

    2015-01-01

    Mirror foot is a very rare congenital anomaly, with only a few papers presenting definitive treatment for this entity. There are limited management recommendations. Most cases are treated before walking age. In our case, there were no associated developmental defects of the leg. The child underwent complex rays resection with medial foot reconstruction. After 7.5 years of followup, definitive surgical treatment was performed with satisfactory cosmetic and functional outcome. PMID:26229172

  17. Construction of Prototype Lightweight Mirrors

    NASA Technical Reports Server (NTRS)

    Robinson, William G.

    1997-01-01

    This contract and the work described was in support of a Seven Segment Demonstrator (SSD) and demonstration of a different technology for construction of lightweight mirrors. The objectives of the SSD were to demonstrate functionality and performance of a seven segment prototype array of hexagonal mirrors and supporting electromechanical components which address design issues critical to space optics deployed in large space based telescopes for astronomy and for optics used in spaced based optical communications systems. The SSD was intended to demonstrate technologies which can support the following capabilities; Transportation in dense packaging to existing launcher payload envelopes, then deployable on orbit to form space telescope with large aperture. Provide very large (less than 10 meters) primary reflectors of low mass and cost. Demonstrate the capability to form a segmented primary or quaternary mirror into a quasi-continuous surface with individual subapertures phased so that near diffraction limited imaging in the visible wavelength region is achieved. Continuous compensation of optical wavefront due to perturbations caused by imperfections, natural disturbances, and equipment induced vibrations/deflections to provide near diffraction limited imaging performance in the visible wavelength region. Demonstrate the feasibility of fabricating such systems with reduced mass and cost compared to past approaches. While the SSD could not be expected to satisfy all of the above capabilities, the intent was to start identifying and understanding new technologies that might be applicable to these goals.

  18. Deflectometric measurement of large mirrors

    NASA Astrophysics Data System (ADS)

    Olesch, Evelyn; Häusler, Gerd; Wörnlein, André; Stinzing, Friedrich; van Eldik, Christopher

    2014-06-01

    We discuss the inspection of large-sized, spherical mirror tiles by `Phase Measuring Deflectometry' (PMD). About 10 000 of such mirror tiles, each satisfying strict requirements regarding the spatial extent of the point-spread-function (PSF), are planned to be installed on the Cherenkov Telescope Array (CTA), a future ground-based instrument to observe the sky in very high energy gamma-rays. Owing to their large radii of curvature of up to 60 m, a direct PSF measurement of these mirrors with concentric geometry requires large space. We present a PMD sensor with a footprint of only 5×2×1.2 m3 that overcomes this limitation. The sensor intrinsically acquires the surface slope; the shape data are calculated by integration. In this way, the PSF can be calculated for real case scenarios, e.g., when the light source is close to infinity and off-axis. The major challenge is the calibration of the PMD sensor, specifically because the PSF data have to be reconstructed from different camera views. The calibration of the setup is described, and measurements presented and compared to results obtained with the direct approach.

  19. Anastigmatic three-mirror telescope. [particularly suited for spaceborne UV observation

    NASA Technical Reports Server (NTRS)

    Korsch, D.

    1977-01-01

    A three-mirror telescope arrangement that can be corrected for four aberrations (coma, spherical aberration, field curvature, and astigmatism) is described. Geometric spot size is less than 0.1 sec of arc, in an easily accessible flat field of 1.5 deg. The primary-secondary configuration is Cassegrain-like, with the real image formed closely behind the primary. This secondary image is re-imaged by a tertiary mirror at roughly unit magnification. A small, flat mirror at the exit pupil, located between primary and tertiary, folds the light rectangularly away from the telescope axis. The shape of the large image area is helpful in space applications where several instruments may share the focal plane.

  20. Woofer-Tweeter Adaptive Optics - Poster Paper

    NASA Astrophysics Data System (ADS)

    Farrell, T. D.; Dainty, J. C.

    2008-01-01

    An optical bench experiment has been assembled to demonstrate the concept of woofer-tweeter adaptive optics for astronomical applications. The system includes an OKO 37 actuator woofer deformable mirror combined with a Boston Micromachines 140 actuator tweeter. The goal of such a system is to achieve a higher degree of wavefront correction not currently possible due to the limitations of deformable mirror technology and cost.