Science.gov

Sample records for adaptive optics technology

  1. 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.

  2. Retinal imaging using adaptive optics technology.

    PubMed

    Kozak, Igor

    2014-04-01

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of wave front distortions. Retinal imaging using AO aims to compensate for higher order aberrations originating from the cornea and the lens by using deformable mirror. The main application of AO retinal imaging has been to assess photoreceptor cell density, spacing, and mosaic regularity in normal and diseased eyes. Apart from photoreceptors, the retinal pigment epithelium, retinal nerve fiber layer, retinal vessel wall and lamina cribrosa can also be visualized with AO technology. Recent interest in AO technology in eye research has resulted in growing number of reports and publications utilizing this technology in both animals and humans. With the availability of first commercially available instruments we are making transformation of AO technology from a research tool to diagnostic instrument. The current challenges include imaging eyes with less than perfect optical media, formation of normative databases for acquired images such as cone mosaics, and the cost of the technology. The opportunities for AO will include more detailed diagnosis with description of some new findings in retinal diseases and glaucoma as well as expansion of AO into clinical trials which has already started. PMID:24843304

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

    PubMed

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

    2012-12-27

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

  4. Adaptive Optics Technology for High-Resolution Retinal Imaging

    PubMed Central

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

    2013-01-01

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging. PMID:23271600

  5. A Wafer Transfer Technology for MEMS Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Yang, Eui-Hyeok; Wiberg, Dean V.

    2001-01-01

    Adaptive optics systems require the combination of several advanced technologies such as precision optics, wavefront sensors, deformable mirrors, and lasers with high-speed control systems. The deformable mirror with a continuous membrane is a key component of these systems. This paper describes a new technique for transferring an entire wafer-level silicon membrane from one substrate to another. This technology is developed for the fabrication of a compact deformable mirror with a continuous facet. A 1 (mu)m thick silicon membrane, 100 mm in diameter, has been successfully transferred without using adhesives or polymers (i.e. wax, epoxy, or photoresist). Smaller or larger diameter membranes can also be transferred using this technique. The fabricated actuator membrane with an electrode gap of 1.5 (mu)m shows a vertical deflection of 0.37 (mu)m at 55 V.

  6. 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.

  7. Adaptation technology between IP layer and optical layer in optical Internet

    NASA Astrophysics Data System (ADS)

    Ji, Yuefeng; Li, Hua; Sun, Yongmei

    2001-10-01

    Wavelength division multiplexing (WDM) optical network provides a platform with high bandwidth capacity and is supposed to be the backbone infrastructure supporting the next-generation high-speed multi-service networks (ATM, IP, etc.). In the foreseeable future, IP will be the predominant data traffic, to make fully use of the bandwidth of the WDM optical network, many attentions have been focused on IP over WDM, which has been proposed as the most promising technology for new kind of network, so-called Optical Internet. According to OSI model, IP is in the 3rd layer (network layer) and optical network is in the 1st layer (physical layer), so the key issue is what adaptation technology should be used in the 2nd layer (data link layer). In this paper, firstly, we analyze and compare the current adaptation technologies used in backbone network nowadays. Secondly, aiming at the drawbacks of above technologies, we present a novel adaptation protocol (DONA) between IP layer and optical layer in Optical Internet and describe it in details. Thirdly, the gigabit transmission adapter (GTA) we accomplished based on the novel protocol is described. Finally, we set up an experiment platform to apply and verify the DONA and GTA, the results and conclusions of the experiment are given.

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

    PubMed

    Merino, David; Loza-Alvarez, Pablo

    2016-01-01

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

  9. Adaptive optics scanning laser ophthalmoscope imaging: technology update

    PubMed Central

    Merino, David; Loza-Alvarez, Pablo

    2016-01-01

    Adaptive optics (AO) retinal imaging has become very popular in the past few years, especially within the ophthalmic research community. Several different retinal techniques, such as fundus imaging cameras or optical coherence tomography systems, have been coupled with AO in order to produce impressive images showing individual cell mosaics over different layers of the in vivo human retina. The combination of AO with scanning laser ophthalmoscopy has been extensively used to generate impressive images of the human retina with unprecedented resolution, showing individual photoreceptor cells, retinal pigment epithelium cells, as well as microscopic capillary vessels, or the nerve fiber layer. Over the past few years, the technique has evolved to develop several different applications not only in the clinic but also in different animal models, thanks to technological developments in the field. These developments have specific applications to different fields of investigation, which are not limited to the study of retinal diseases but also to the understanding of the retinal function and vision science. This review is an attempt to summarize these developments in an understandable and brief manner in order to guide the reader into the possibilities that AO scanning laser ophthalmoscopy offers, as well as its limitations, which should be taken into account when planning on using it. PMID:27175057

  10. [Adaptive optics for ophthalmology].

    PubMed

    Saleh, M

    2016-04-01

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

  11. RAVEN, a Multi-Object Adaptive Optics technology and science demonstrator

    NASA Astrophysics Data System (ADS)

    Andersen, Dave; Blain, Célia; Bradley, Colin; Gamroth, Darryl; Ito, Meguru; Jackson, Kate; Lardière, Olivier; Nash, Reston; Oya, Shin; Pham, Laurie; Robertson, Dave; Véran, Jean-Pierre

    2011-09-01

    The University of Victoria Adaptive Optics Laboratory, the Herzberg Institute of Astrophysics and Subaru Observatory are undertaking a preliminary design study for a Multi-Object Adaptive Optics (MOAO) technology and science demonstrator called Raven. Raven will be mounted on the Subaru NIR Nasmyth platform and will feed the IRCS imager and spectrograph. The baseline design calls for three natural guide star (NGS) wavefront sensors (WFS), one on-axis laser guide star (LGS) WFS and two science pickoff arms that will patrol a 2 arcminute diameter field of regard (FOR). Sky coverage is an important consideration for a science demonstrator. End-to-end simulations of Raven show that a 10x10 subaperture adaptive optics (AO) system can meet the science requirements, i.e. 30% of the energy ensquared (EE) within a 140mas slit using three R<14 NGSs, and 40% EE with the addition of the central LGS. An overview of the Raven project is presented, including the top-level requirements, science cases, opto-mechanical design, calibration procedures and the hardware and software architecture.

  12. Adaptive optics ophthalmoscopy

    PubMed Central

    Roorda, Austin; Duncan, Jacque L.

    2016-01-01

    This review starts with a brief history and description of adaptive optics (AO) technology, followed by a showcase of the latest capabilities of AO systems for imaging the human retina and an extensive review of the literature on where AO is being used clinically. The review concludes with a discussion on future directions and guidance on usage and interpretation of images from AO systems for the eye. PMID:26973867

  13. Demonstration of new technology MEMS and liquid crystal adaptive optics on bright astronomical objects and satellites.

    PubMed

    Dayton, David; Gonglewski, John; Restaino, Sergio; Martin, Jeffrey; Phillips, James; Hartman, Mary; Kervin, Paul; Snodgress, Joshua; Browne, Stephen; Heimann, Nevin; Shilko, Michael; Pohle, Richard; Carrion, Bill; Smith, Clint; Thiel, Daniel

    2002-12-16

    We present here results using two novel adaptive optic elements, an electro-static membrane mirror, and a dual frequency nematic liquid crystal. These devices have the advantage of low cost, low power consumption, and compact size. Possible applications of the devices are astronomical adaptive optics, laser beam control, laser cavity mode control, and real time holography. Field experiments were performed on the Air Force Research Laboratory, Directed Energy Directorate's 3.67 meter AMOS telescope on Maui, Hawaii.

  14. Demonstration of new technology MEMS and liquid crystal adaptive optics on bright astronomical objects and satellites.

    PubMed

    Dayton, David; Gonglewski, John; Restaino, Sergio; Martin, Jeffrey; Phillips, James; Hartman, Mary; Kervin, Paul; Snodgress, Joshua; Browne, Stephen; Heimann, Nevin; Shilko, Michael; Pohle, Richard; Carrion, Bill; Smith, Clint; Thiel, Daniel

    2002-12-16

    We present here results using two novel adaptive optic elements, an electro-static membrane mirror, and a dual frequency nematic liquid crystal. These devices have the advantage of low cost, low power consumption, and compact size. Possible applications of the devices are astronomical adaptive optics, laser beam control, laser cavity mode control, and real time holography. Field experiments were performed on the Air Force Research Laboratory, Directed Energy Directorate's 3.67 meter AMOS telescope on Maui, Hawaii. PMID:19461686

  15. Retinal Imaging: Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Goncharov, A. S.; Iroshnikov, N. G.; Larichev, Andrey V.

    This chapter describes several factors influencing the performance of ophthalmic diagnostic systems with adaptive optics compensation of human eye aberration. Particular attention is paid to speckle modulation, temporal behavior of aberrations, and anisoplanatic effects. The implementation of a fundus camera with adaptive optics is considered.

  16. Coherent optical adaptive techniques.

    PubMed

    Bridges, W B; Brunner, P T; Lazzara, S P; Nussmeier, T A; O'Meara, T R; Sanguinet, J A; Brown, W P

    1974-02-01

    The theory of multidither adaptive optical radar phased arrays is briefly reviewed as an introduction to the experimental results obtained with seven-element linear and three-element triangular array systems operating at 0.6328 microm. Atmospheric turbulence compensation and adaptive tracking capabilities are demonstrated.

  17. Telescope Adaptive Optics Code

    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 defaultmore » 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« less

  18. Solar tomography adaptive optics.

    PubMed

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

    2014-03-10

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

  19. Advancing adaptive optics technology: Laboratory turbulence simulation and optimization of laser guide stars

    NASA Astrophysics Data System (ADS)

    Rampy, Rachel A.

    Since Galileo's first telescope some 400 years ago, astronomers have been building ever-larger instruments. Yet only within the last two decades has it become possible to realize the potential angular resolutions of large ground-based telescopes, by using adaptive optics (AO) technology to counter the blurring effects of Earth's atmosphere. And only within the past decade have the development of laser guide stars (LGS) extended AO capabilities to observe science targets nearly anywhere in the sky. Improving turbulence simulation strategies and LGS are the two main topics of my research. In the first part of this thesis, I report on the development of a technique for manufacturing phase plates for simulating atmospheric turbulence in the laboratory. The process involves strategic application of clear acrylic paint onto a transparent substrate. Results of interferometric characterization of the plates are described and compared to Kolmogorov statistics. The range of r0 (Fried's parameter) achieved thus far is 0.2--1.2 mm at 650 nm measurement wavelength, with a Kolmogorov power law. These plates proved valuable at the Laboratory for Adaptive Optics at University of California, Santa Cruz, where they have been used in the Multi-Conjugate Adaptive Optics testbed, during integration and testing of the Gemini Planet Imager, and as part of the calibration system of the on-sky AO testbed named ViLLaGEs (Visible Light Laser Guidestar Experiments). I present a comparison of measurements taken by ViLLaGEs of the power spectrum of a plate and the real sky turbulence. The plate is demonstrated to follow Kolmogorov theory well, while the sky power spectrum does so in a third of the data. This method of fabricating phase plates has been established as an effective and low-cost means of creating simulated turbulence. Due to the demand for such devices, they are now being distributed to other members of the AO community. The second topic of this thesis pertains to understanding and

  20. Advancing adaptive optics technology: Laboratory turbulence simulation and optimization of laser guide stars

    NASA Astrophysics Data System (ADS)

    Rampy, Rachel A.

    Since Galileo's first telescope some 400 years ago, astronomers have been building ever-larger instruments. Yet only within the last two decades has it become possible to realize the potential angular resolutions of large ground-based telescopes, by using adaptive optics (AO) technology to counter the blurring effects of Earth's atmosphere. And only within the past decade have the development of laser guide stars (LGS) extended AO capabilities to observe science targets nearly anywhere in the sky. Improving turbulence simulation strategies and LGS are the two main topics of my research. In the first part of this thesis, I report on the development of a technique for manufacturing phase plates for simulating atmospheric turbulence in the laboratory. The process involves strategic application of clear acrylic paint onto a transparent substrate. Results of interferometric characterization of the plates are described and compared to Kolmogorov statistics. The range of r0 (Fried's parameter) achieved thus far is 0.2--1.2 mm at 650 nm measurement wavelength, with a Kolmogorov power law. These plates proved valuable at the Laboratory for Adaptive Optics at University of California, Santa Cruz, where they have been used in the Multi-Conjugate Adaptive Optics testbed, during integration and testing of the Gemini Planet Imager, and as part of the calibration system of the on-sky AO testbed named ViLLaGEs (Visible Light Laser Guidestar Experiments). I present a comparison of measurements taken by ViLLaGEs of the power spectrum of a plate and the real sky turbulence. The plate is demonstrated to follow Kolmogorov theory well, while the sky power spectrum does so in a third of the data. This method of fabricating phase plates has been established as an effective and low-cost means of creating simulated turbulence. Due to the demand for such devices, they are now being distributed to other members of the AO community. The second topic of this thesis pertains to understanding and

  1. Technology transfer for adaptation

    NASA Astrophysics Data System (ADS)

    Biagini, Bonizella; Kuhl, Laura; Gallagher, Kelly Sims; Ortiz, Claudia

    2014-09-01

    Technology alone will not be able to solve adaptation challenges, but it is likely to play an important role. As a result of the role of technology in adaptation and the importance of international collaboration for climate change, technology transfer for adaptation is a critical but understudied issue. Through an analysis of Global Environment Facility-managed adaptation projects, we find there is significantly more technology transfer occurring in adaptation projects than might be expected given the pessimistic rhetoric surrounding technology transfer for adaptation. Most projects focused on demonstration and early deployment/niche formation for existing technologies rather than earlier stages of innovation, which is understandable considering the pilot nature of the projects. Key challenges for the transfer process, including technology selection and appropriateness under climate change, markets and access to technology, and diffusion strategies are discussed in more detail.

  2. Initial concepts for CELT adaptive optics

    NASA Astrophysics Data System (ADS)

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

    2003-02-01

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

  3. Adaptive Optical Scanning Holography

    PubMed Central

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

    2016-01-01

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

  4. Small scale adaptive optics experiment systems engineering

    NASA Technical Reports Server (NTRS)

    Boykin, William H.

    1993-01-01

    Assessment of the current technology relating to the laser power beaming system which in full scale is called the Beam Transmission Optical System (BTOS). Evaluation of system integration efforts are being conducted by the various government agencies and industry. Concepts are being developed for prototypes of adaptive optics for a BTOS.

  5. Adaptive optical interconnects: the ADDAPT project

    NASA Astrophysics Data System (ADS)

    Henker, Ronny; Pliva, Jan; Khafaji, Mahdi; Ellinger, Frank; Toifl, Thomas; Offrein, Bert; Cevrero, Alessandro; Oezkaya, Ilter; Seifried, Marc; Ledentsov, Nikolay; Kropp, Joerg-R.; Shchukin, Vitaly; Zoldak, Martin; Halmo, Leos; Turkiewicz, Jaroslaw; Meredith, Wyn; Eddie, Iain; Georgiades, Michael; Charalambides, Savvas; Duis, Jeroen; van Leeuwen, Pieter

    2015-09-01

    Existing optical networks are driven by dynamic user and application demands but operate statically at their maximum performance. Thus, optical links do not offer much adaptability and are not very energy-efficient. In this paper a novel approach of implementing performance and power adaptivity from system down to optical device, electrical circuit and transistor level is proposed. Depending on the actual data load, the number of activated link paths and individual device parameters like bandwidth, clock rate, modulation format and gain are adapted to enable lowering the components supply power. This enables flexible energy-efficient optical transmission links which pave the way for massive reductions of CO2 emission and operating costs in data center and high performance computing applications. Within the FP7 research project Adaptive Data and Power Aware Transceivers for Optical Communications (ADDAPT) dynamic high-speed energy-efficient transceiver subsystems are developed for short-range optical interconnects taking up new adaptive technologies and methods. The research of eight partners from industry, research and education spanning seven European countries includes the investigation of several adaptive control types and algorithms, the development of a full transceiver system, the design and fabrication of optical components and integrated circuits as well as the development of high-speed, low loss packaging solutions. This paper describes and discusses the idea of ADDAPT and provides an overview about the latest research results in this field.

  6. Adaptive Optics Communications Performance Analysis

    NASA Technical Reports Server (NTRS)

    Srinivasan, M.; Vilnrotter, V.; Troy, M.; Wilson, K.

    2004-01-01

    The performance improvement obtained through the use of adaptive optics for deep-space communications in the presence of atmospheric turbulence is analyzed. Using simulated focal-plane signal-intensity distributions, uncoded pulse-position modulation (PPM) bit-error probabilities are calculated assuming the use of an adaptive focal-plane detector array as well as an adaptively sized single detector. It is demonstrated that current practical adaptive optics systems can yield performance gains over an uncompensated system ranging from approximately 1 dB to 6 dB depending upon the PPM order and background radiation level.

  7. Adaptive optics applications in vision science

    NASA Astrophysics Data System (ADS)

    Olivier, Scot S.

    2003-06-01

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

  8. Adaptive Optics Applications in Vision Science

    SciTech Connect

    Olivier, S S

    2003-03-17

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

  9. Adaptive optical zoom sensor.

    SciTech Connect

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

    2005-11-01

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

  10. Adaptive Optics at Lawrence Livermore National Laboratory

    SciTech Connect

    Gavel, D T

    2003-03-10

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

  11. Adaptive Optics for Large Telescopes

    SciTech Connect

    Olivier, S

    2008-06-27

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

  12. Integrated optics technology study

    NASA Technical Reports Server (NTRS)

    Chen, B.; Findakly, T.; Innarella, R.

    1982-01-01

    The status and near term potential of materials and processes available for the fabrication of single mode integrated electro-optical components are discussed. Issues discussed are host material and orientation, waveguide formation, optical loss mechanisms, wavelength selection, polarization effects and control, laser to integrated optics coupling fiber optic waveguides to integrated optics coupling, sources, and detectors. Recommendations of the best materials, technology, and processes for fabrication of integrated optical components for communications and fiber gyro applications are given.

  13. Fiber Optics Technology.

    ERIC Educational Resources Information Center

    Burns, William E.

    1986-01-01

    Discusses various applications of fiber optics technology: information systems, industrial robots, medicine, television, transportation, and training. Types of jobs that will be available with fiber optics training (such as electricians and telephone cable installers and splicers) are examined. (CT)

  14. Integrated optics technology study

    NASA Technical Reports Server (NTRS)

    Chen, B.

    1982-01-01

    The materials and processes available for the fabrication of single mode integrated electrooptical components are described. Issues included in the study are: (1) host material and orientation, (2) waveguide formation, (3) optical loss mechanisms, (4) wavelength selection, (5) polarization effects and control, (6) laser to integrated optics coupling,(7) fiber optic waveguides to integrated optics coupling, (8) souces, (9) detectors. The best materials, technology and processes for fabrication of integrated optical components for communications and fiber gyro applications are recommended.

  15. Adaptive optics and laser guide stars at Lick observatory

    SciTech Connect

    Brase, J.M.

    1994-11-15

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

  16. Performance of the optical communication adaptive optics testbed

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  17. Future trends in adaptive Optics

    NASA Astrophysics Data System (ADS)

    Le Louarn, Miska

    2001-05-01

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

  18. Adaptive Optics for Industry and Medicine

    NASA Astrophysics Data System (ADS)

    Dainty, Christopher

    2008-01-01

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

  19. Polymer optical motherboard technology

    NASA Astrophysics Data System (ADS)

    Keil, N.; Yao, H.; Zawadzki, C.; Grote, N.; Schell, M.

    2008-02-01

    In this paper, different hybridly integrated optical devices including optical multiplexer/ demultiplexer and optical transceivers are described. The devices were made using polymer planar light wave circuit (P2LC) technology. Laser diodes, photodiodes, and thin-film filters have been integrated. Key issues involved in this technology, in particular the coupling between laser diodes and polymer waveguides, and between waveguides and photodiodes and also fibers are discussed.

  20. Intelligent Optical Systems Using Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Clark, Natalie

    2012-01-01

    Until recently, the phrase adaptive optics generally conjured images of large deformable mirrors being integrated into telescopes to compensate for atmospheric turbulence. However, the development of smaller, cheaper devices has sparked interest for other aerospace and commercial applications. Variable focal length lenses, liquid crystal spatial light modulators, tunable filters, phase compensators, polarization compensation, and deformable mirrors are becoming increasingly useful for other imaging applications including guidance navigation and control (GNC), coronagraphs, foveated imaging, situational awareness, autonomous rendezvous and docking, non-mechanical zoom, phase diversity, and enhanced multi-spectral imaging. The active components presented here allow flexibility in the optical design, increasing performance. In addition, the intelligent optical systems presented offer advantages in size and weight and radiation tolerance.

  1. Physics and Advanced Technologies LDRD Final Report:Adaptive Optics Imaging and Spectroscopy of the Solar System

    SciTech Connect

    Gibbard, S; Max, C; Macintosh, B; Grossman, A

    2004-01-21

    This focus of this project was the investigation of the planets Uranus and Neptune and Saturn's moon Titan using adaptive optics imaging and spectroscopy at the 10-meter W.M. Keck Telescopes. These bodies share a common type of atmosphere, one that is rich in methane and has a hydrocarbon haze layer produced by methane photolysis. Neptune and Uranus have atmospheric features which change on short timescales; we have investigated their altitude, composition, and connection to events occurring deeper in the planets' tropospheres. Titan has a solid surface located under its atmosphere, the composition of which is still quite uncertain. With spectra that sample the vertical structure of the atmosphere and narrowband observations that selectively probe Titan's surface we have determined the surface reflectivity of Titan at near-infrared wavelengths.

  2. Adaptive Optics for the Human Eye

    NASA Astrophysics Data System (ADS)

    Williams, D. R.

    2000-05-01

    Adaptive optics can extend not only the resolution of ground-based telescopes, but also the human eye. Both static and dynamic aberrations in the cornea and lens of the normal eye limit its optical quality. Though it is possible to correct defocus and astigmatism with spectacle lenses, higher order aberrations remain. These aberrations blur vision and prevent us from seeing at the fundamental limits set by the retina and brain. They also limit the resolution of cameras to image the living retina, cameras that are a critical for the diagnosis and treatment of retinal disease. I will describe an adaptive optics system that measures the wave aberration of the eye in real time and compensates for it with a deformable mirror, endowing the human eye with unprecedented optical quality. This instrument provides fresh insight into the ultimate limits on human visual acuity, reveals for the first time images of the retinal cone mosaic responsible for color vision, and points the way to contact lenses and laser surgical methods that could enhance vision beyond what is currently possible today. Supported by the NSF Science and Technology Center for Adaptive Optics, the National Eye Institute, and Bausch and Lomb, Inc.

  3. Advanced optical instruments technology

    NASA Technical Reports Server (NTRS)

    Shao, Mike; Chrisp, Michael; Cheng, Li-Jen; Eng, Sverre; Glavich, Thomas; Goad, Larry; Jones, Bill; Kaarat, Philip; Nein, Max; Robinson, William

    1992-01-01

    The science objectives for proposed NASA missions for the next decades push the state of the art in sensitivity and spatial resolution over a wide range of wavelengths, including the x-ray to the submillimeter. While some of the proposed missions are larger and more sensitive versions of familiar concepts, such as the next generation space telescope, others use concepts, common on the Earth, but new to space, such as optical interferometry, in order to provide spatial resolutions impossible with other concepts. However, despite their architecture, the performance of all of the proposed missions depends critically on the back-end instruments that process the collected energy to produce scientifically interesting outputs. The Advanced Optical Instruments Technology panel was chartered with defining technology development plans that would best improve optical instrument performance for future astrophysics missions. At this workshop the optical instrument was defined as the set of optical components that reimage the light from the telescope onto the detectors to provide information about the spatial, spectral, and polarization properties of the light. This definition was used to distinguish the optical instrument technology issues from those associated with the telescope, which were covered by a separate panel. The panel identified several areas for optical component technology development: diffraction gratings; tunable filters; interferometric beam combiners; optical materials; and fiber optics. The panel also determined that stray light suppression instruments, such as coronagraphs and nulling interferometers, were in need of general development to support future astrophysics needs.

  4. Active optics, adaptive optics, and laser guide stars.

    PubMed

    Hubin, N; Noethe, L

    1993-11-26

    Optical astronomy is crucial to our understanding of the universe, but the capabilities of ground-based telescopes are severely limited by the effects of telescope errors and of the atmosphere on the passage of light. Recently, it has become possible to construct inbuilt corrective devices that can compensate for both types of degradations as observations are conducted. For full use of the newly emerged class of 8-meter telescopes, such active corrective capabilities, known as active and adaptive optics, are essential. Some physical limitations in the adaptive optics field can be overcome by artificially created reference stars, called laser guide stars. These new technologies have lately been applied with success to some medium and very large telescopes. PMID:17736819

  5. Driver Code for Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Rao, Shanti

    2007-01-01

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

  6. Specialized wavefront sensors for adaptive optics

    NASA Astrophysics Data System (ADS)

    Neal, Daniel R.; Mansell, J. D.; Gruetzner, James K.; Morgan, R.; Warren, Mial E.

    1995-08-01

    The performance of an adaptive optical system is strongly dependent upon correctly measuring the wavefront of the arriving light. The most common wavefront measurement techniques used to date are the shearing interferometer and the Shack-Hartmann sensor. Shack-Hartmann sensors rely on the use of lenslet arrays to sample the aperture appropriately. These have traditionally been constructed using MLM or step and repeat technology, and more recently with binary optics technology. Diffractive optics fabrication methodology can be used to remove some of the limitations of the previous technologies and can allow for low-cost production of sophisticated elements. We have investigated several different specialized wavefront sensor configurations using both Shack-Hartmann and shearing interferometer principles. We have taken advantage of the arbitrary nature of these elements to match pupil shapes of detector and telescope aperture and to introduce magnification between the lenslet array and the detector. We have fabricated elements that facilitate matching the sampling to the current atmospheric conditions. The sensors were designed using a far-field diffraction model and a photolithography layout program. They were fabricated using photolithography and RIE etching. Several different designs are presented with some experimental results from a small-scale adaptive optics brass-board.

  7. 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.

  8. Retinal imaging using adaptive optics technology☆

    PubMed Central

    Kozak, Igor

    2014-01-01

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of wave front distortions. Retinal imaging using AO aims to compensate for higher order aberrations originating from the cornea and the lens by using deformable mirror. The main application of AO retinal imaging has been to assess photoreceptor cell density, spacing, and mosaic regularity in normal and diseased eyes. Apart from photoreceptors, the retinal pigment epithelium, retinal nerve fiber layer, retinal vessel wall and lamina cribrosa can also be visualized with AO technology. Recent interest in AO technology in eye research has resulted in growing number of reports and publications utilizing this technology in both animals and humans. With the availability of first commercially available instruments we are making transformation of AO technology from a research tool to diagnostic instrument. The current challenges include imaging eyes with less than perfect optical media, formation of normative databases for acquired images such as cone mosaics, and the cost of the technology. The opportunities for AO will include more detailed diagnosis with description of some new findings in retinal diseases and glaucoma as well as expansion of AO into clinical trials which has already started. PMID:24843304

  9. Applications of Adaptive Optics Scanning Laser Ophthalmoscopy

    PubMed Central

    Roorda, Austin

    2010-01-01

    Adaptive optics (AO) describes a set of tools to correct or control aberrations in any optical system. In the eye, AO allows for precise control of the ocular aberrations. If used to correct aberrations over a large pupil, for example, cellular level resolution in retinal images can be achieved. AO systems have been demonstrated for advanced ophthalmoscopy as well as for testing and/or improving vision. In fact, AO can be integrated to any ophthalmic instrument where the optics of the eye is involved, with a scope of applications ranging from phoropters to optical coherence tomography systems. In this paper, I discuss the applications and advantages of using AO in a specific system, the adaptive optics scanning laser ophthalmoscope, or AOSLO. Since the Borish award was, in part, awarded to me because of this effort, I felt it appropriate to select this as the topic for this paper. Furthermore, users of AOSLO continue to appreciate the benefits of the technology, some of which were not anticipated at the time of development, and so it is time to revisit this topic and summarize them in a single paper. PMID:20160657

  10. Adaptive Optics for Industry and Medicine

    NASA Astrophysics Data System (ADS)

    Dainty, Christopher

    2008-01-01

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

  11. 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.

  12. Adaptive optics for peripheral vision

    NASA Astrophysics Data System (ADS)

    Rosén, R.; Lundström, L.; Unsbo, P.

    2012-07-01

    Understanding peripheral optical errors and their impact on vision is important for various applications, e.g. research on myopia development and optical correction of patients with central visual field loss. In this study, we investigated whether correction of higher order aberrations with adaptive optics (AO) improve resolution beyond what is achieved with best peripheral refractive correction. A laboratory AO system was constructed for correcting peripheral aberrations. The peripheral low contrast grating resolution acuity in the 20° nasal visual field of the right eye was evaluated for 12 subjects using three types of correction: refractive correction of sphere and cylinder, static closed loop AO correction and continuous closed loop AO correction. Running AO in continuous closed loop improved acuity compared to refractive correction for most subjects (maximum benefit 0.15 logMAR). The visual improvement from aberration correction was highly correlated with the subject's initial amount of higher order aberrations (p = 0.001, R 2 = 0.72). There was, however, no acuity improvement from static AO correction. In conclusion, correction of peripheral higher order aberrations can improve low contrast resolution, provided refractive errors are corrected and the system runs in continuous closed loop.

  13. Design considerations for CELT adaptive optics

    NASA Astrophysics Data System (ADS)

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

    2000-07-01

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

  14. Keck adaptive optics: control subsystem

    SciTech Connect

    Brase, J.M.; An, J.; Avicola, K.

    1996-03-08

    Adaptive optics on the Keck 10 meter telescope will provide an unprecedented level of capability in high resolution ground based astronomical imaging. The system is designed to provide near diffraction limited imaging performance with Strehl {gt} 0.3 n median Keck seeing of r0 = 25 cm, T =10 msec at 500 nm wavelength. The system will be equipped with a 20 watt sodium laser guide star to provide nearly full sky coverage. The wavefront control subsystem is responsible for wavefront sensing and the control of the tip-tilt and deformable mirrors which actively correct atmospheric turbulence. The spatial sampling interval for the wavefront sensor and deformable mirror is de=0.56 m which gives us 349 actuators and 244 subapertures. This paper summarizes the wavefront control system and discusses particular issues in designing a wavefront controller for the Keck telescope.

  15. Electron density measurements for plasma adaptive optics

    NASA Astrophysics Data System (ADS)

    Neiswander, Brian W.

    Over the past 40 years, there has been growing interest in both laser communications and directed energy weapons that operate from moving aircraft. As a laser beam propagates from an aircraft in flight, it passes through boundary layers, turbulence, and shear layers in the near-region of the aircraft. These fluid instabilities cause strong density gradients which adversely affect the transmission of laser energy to a target. Adaptive optics provides corrective measures for this problem but current technology cannot respond quickly enough to be useful for high speed flight conditions. This research investigated the use of plasma as a medium for adaptive optics for aero-optics applications. When a laser beam passes through plasma, its phase is shifted proportionally to the electron density and gas heating within the plasma. As a result, plasma can be utilized as a dynamically controllable optical medium. Experiments were carried out using a cylindrical dielectric barrier discharge plasma chamber which generated a sub-atmospheric pressure, low-temperature plasma. An electrostatic model of this design was developed and revealed an important design constraint relating to the geometry of the chamber. Optical diagnostic techniques were used to characterize the plasma discharge. Single-wavelength interferometric experiments were performed and demonstrated up to 1.5 microns of optical path difference (OPD) in a 633 nm laser beam. Dual-wavelength interferometry was used to obtain time-resolved profiles of the plasma electron density and gas heating inside the plasma chamber. Furthermore, a new multi-wavelength infrared diagnostic technique was developed and proof-of-concept simulations were conducted to demonstrate the system's capabilities.

  16. Adaptive optics for space debris tracking

    NASA Astrophysics Data System (ADS)

    Bennet, Francis; D'Orgeville, Celine; Gao, Yue; Gardhouse, William; Paulin, Nicolas; Price, Ian; Rigaut, Francois; Ritchie, Ian T.; Smith, Craig H.; Uhlendorf, Kristina; Wang, Yanjie

    2014-07-01

    Space debris in Low Earth Orbit (LEO) is becoming an increasing threat to satellite and spacecraft. A reliable and cost effective method for detecting possible collisions between orbiting objects is required to prevent an exponential growth in the number of debris. Current RADAR survey technologies used to monitor the orbits of thousands of space debris objects are relied upon to manoeuvre operational satellites to prevent possible collisions. A complimentary technique, ground-based laser LIDAR (Light Detection and Ranging) have been used to track much smaller objects with higher accuracy than RADAR, giving greater prediction of possible collisions and avoiding unnecessary manoeuvring. Adaptive optics will play a key role in any ground based LIDAR tracking system as a cost effective way of utilising smaller ground stations or less powerful lasers. The use of high power and high energy lasers for the orbital modification of debris objects will also require an adaptive optic system to achieve the high photon intensity on the target required for photon momentum transfer and laser ablation. EOS Space Systems have pioneered the development of automated laser space debris tracking for objects in low Earth orbit. The Australian National University have been developing an adaptive optics system to improve this space debris tracking capability at the EOS Space Systems Mount Stromlo facility in Canberra, Australia. The system is integrated with the telescope and commissioned as an NGS AO system before moving on to LGS AO and tracking operations. A pulsed laser propagated through the telescope is used to range the target using time of flight data. Adaptive optics is used to increase the maximum range and number or targets available to the LIDAR system, by correcting the uplink laser beam. Such a system presents some unique challenges for adaptive optics: high power lasers reflecting off deformable mirrors, high slew rate tracking, and variable off-axis tracking correction. A

  17. Fiber-Optic Sensing Technology

    SciTech Connect

    Milnes, M.; Baylor, L.C.; Bave, S.

    1996-10-24

    This article offers a basic review of fiber-optic sensing technology, or more specifically, fiber-optic sensing technology as applied to the qualitative or quantitative identification of a chemical sample, and how it works,

  18. Adaptive optics imaging of the retina.

    PubMed

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

    2014-01-01

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

  19. Adaptive optics imaging of the retina

    PubMed Central

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

    2014-01-01

    Adaptive optics is a relatively new tool that is available to ophthalmologists for study of cellular level details. In addition to the axial resolution provided by the spectral-domain optical coherence tomography, adaptive optics provides an excellent lateral resolution, enabling visualization of the photoreceptors, blood vessels and details of the optic nerve head. We attempt a mini review of the current role of adaptive optics in retinal imaging. PubMed search was performed with key words Adaptive optics OR Retina OR Retinal imaging. Conference abstracts were searched from the Association for Research in Vision and Ophthalmology (ARVO) and American Academy of Ophthalmology (AAO) meetings. In total, 261 relevant publications and 389 conference abstracts were identified. PMID:24492503

  20. Adaptive optical ghost imaging through atmospheric turbulence.

    PubMed

    Shi, Dongfeng; Fan, Chengyu; Zhang, Pengfei; Zhang, Jinghui; Shen, Hong; Qiao, Chunhong; Wang, Yingjian

    2012-12-17

    We demonstrate for the first time (to our knowledge) that a high-quality image can still be obtained in atmospheric turbulence by applying adaptive optical ghost imaging (AOGI) system even when conventional ghost imaging system fails to produce an image. The performance of AOGI under different strength of atmospheric turbulence is investigated by simulation. The influence of adaptive optics system with different numbers of adaptive mirror elements on obtained image quality is also studied.

  1. 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.

  2. Adaptive atom-optics in atom interferometry

    NASA Astrophysics Data System (ADS)

    Marable, M. L.; Savard, T. A.; Thomas, J. E.

    1997-02-01

    We suggest a general technique for creating virtual atom-optical elements which are adaptive. The shape and position of these elements is determined by the frequency distribution for optical fields which induce transitions in a high gradient potential. This adaptive method is demonstrated in an all-optical atom interferometer, by creating either a variable optical slit or a variable optical grating which is scanned across the atomic spatial patterns to measure the fringes. This method renders mechanical motion of the interferometer elements unnecessary.

  3. Daytime adaptive optics for deep space optical communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith; Troy, M.; Srinivasan, M.; Platt, B.; Vilnrotter, V.; Wright, M.; Garkanian, V.; Hemmati, H.

    2003-01-01

    The deep space optical communications subsystem offers a higher bandwidth communications link in smaller size, lower mass, and lower power consumption subsystem than does RF. To demonstrate the benefit of this technology to deep space communications NASA plans to launch an optical telecommunications package on the 2009 Mars Telecommunications orbiter spacecraft. Current performance goals are 30-Mbps from opposition, and 1-Mbps near conjunction (-3 degrees Sun-Earth-Probe angle). Yet, near conjunction the background noise from the day sky will degrade the performance of the optical link. Spectral and spatial filtering and higher modulation formats can mitigate the effects of background sky. Narrowband spectral filters can result in loss of link margin, and higher modulation formats require higher transmitted peak powers. In contrast, spatial filtering at the receiver has the potential of being lossless while providing the required sky background rejection. Adaptive optics techniques can correct wave front aberrations caused by atmospheric turbulence and enable near-diffraction-limited performance of the receiving telescope. Such performance facilitates spatial filtering, and allows the receiver field-of-view and hence the noise from the sky background to be reduced.

  4. Adaptive optics program at TMT

    NASA Astrophysics Data System (ADS)

    Boyer, C.; Adkins, Sean; Andersen, David R.; Atwood, Jenny; Bo, Yong; Byrnes, Peter; Caputa, Kris; Cavaco, Jeff; Ellerbroek, Brent; Gilles, Luc; Gregory, James; Herriot, Glen; Hickson, Paul; Ljusic, Zoran; Manter, Darren; Marois, Christian; Otárola, Angel; Pagès, Hubert; Schoeck, Matthias; Sinquin, Jean-Christophe; Smith, Malcolm; Spano, Paolo; Szeto, Kei; Tang, Jinlong; Travouillon, Tony; Véran, Jean-Pierre; Wang, Lianqi; Wei, Kai

    2014-07-01

    The TMT first light Adaptive Optics (AO) facility consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). NFIRAOS is a 60 × 60 laser guide star (LGS) multi-conjugate AO (MCAO) system, which provides uniform, diffraction-limited performance in the J, H, and K bands over 17-30 arc sec diameter fields with 50 per cent sky coverage at the galactic pole, as required to support the TMT science cases. NFIRAOS includes two deformable mirrors, six laser guide star wavefront sensors, and three low-order, infrared, natural guide star wavefront sensors within each client instrument. The first light LGSF system includes six sodium lasers required to generate the NFIRAOS laser guide stars. In this paper, we will provide an update on the progress in designing, modeling and validating the TMT first light AO systems and their components over the last two years. This will include pre-final design and prototyping activities for NFIRAOS, preliminary design and prototyping activities for the LGSF, design and prototyping for the deformable mirrors, fabrication and tests for the visible detectors, benchmarking and comparison of different algorithms and processing architecture for the Real Time Controller (RTC) and development and tests of prototype candidate lasers. Comprehensive and detailed AO modeling is continuing to support the design and development of the first light AO facility. Main modeling topics studied during the last two years include further studies in the area of wavefront error budget, sky coverage, high precision astrometry for the galactic center and other observations, high contrast imaging with NFIRAOS and its first light instruments, Point Spread Function (PSF) reconstruction for LGS MCAO, LGS photon return and sophisticated low order mode temporal filtering.

  5. On the possibility of intraocular adaptive optics

    NASA Astrophysics Data System (ADS)

    Vdovin, Gleb; Loktev, Mikhail; Naumov, Alexander

    2003-04-01

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

  6. 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.

  7. Background Noise Mitigation in Deep-Space Optical Communications Using Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Lee, S.; Wilson, K. E.; Troy, M.

    2005-05-01

    Over the last decade, adaptive optics technology has moved from the purview of a Department of Defense laboratory to astronomical telescopes around the world, and recently to industry, where adaptive optics systems have been developed to correct atmospheric-induced signal fades on high-bandwidth horizontal-path optical links. As JPL develops optical communications technology for high-bandwidth optical links from its deep-space probes, we are exploring the application of adaptive optics to the optical deep-space receiver to improve the quality of the link under turbulent atmospheric and high-background conditions. To provide maximum communications support, the operational deep-space optical communications receiver will need to point close to the Sun or to a bright Sun-illuminated planet. Under these conditions, the background noise from the sky degrades the quality of the optical link, especially when the atmospheric seeing is poor. In this work, we analyze how adaptive optics could be used to mitigate the effects of sky and planetary background noise on the deep-space optical communications receiver's performance in poor seeing conditions. Our results show that, under nominal background sky conditions, gains of 4 dB can be achieved for the uncoded bit-error rate of 0.01.

  8. DKIST Adaptive Optics System: Simulation Results

    NASA Astrophysics Data System (ADS)

    Marino, Jose; Schmidt, Dirk

    2016-05-01

    The 4 m class Daniel K. Inouye Solar Telescope (DKIST), currently under construction, will be equipped with an ultra high order solar adaptive optics (AO) system. The requirements and capabilities of such a solar AO system are beyond those of any other solar AO system currently in operation. We must rely on solar AO simulations to estimate and quantify its performance.We present performance estimation results of the DKIST AO system obtained with a new solar AO simulation tool. This simulation tool is a flexible and fast end-to-end solar AO simulator which produces accurate solar AO simulations while taking advantage of current multi-core computer technology. It relies on full imaging simulations of the extended field Shack-Hartmann wavefront sensor (WFS), which directly includes important secondary effects such as field dependent distortions and varying contrast of the WFS sub-aperture images.

  9. The Coming of Age of Adaptive Optics

    NASA Astrophysics Data System (ADS)

    1995-10-01

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

  10. Adaptive-optics performance of Antarctic telescopes.

    PubMed

    Lawrence, Jon S

    2004-02-20

    The performance of natural guide star adaptive-optics systems for telescopes located on the Antarctic plateau is evaluated and compared with adaptive-optics systems operated with the characteristic mid-latitude atmosphere found at Mauna Kea. A 2-m telescope with tip-tilt correction and an 8-m telescope equipped with a high-order adaptive-optics system are considered. Because of the large isoplanatic angle of the South Pole atmosphere, the anisoplanatic error associated with an adaptive-optics correction is negligible, and the achievable resolution is determined only by the fitting error associated with the number of corrected wave-front modes, which depends on the number of actuators on the deformable mirror. The usable field of view of an adaptive-optics equipped Antarctic telescope is thus orders of magnitude larger than for a similar telescope located at a mid-latitude site; this large field of view obviates the necessity for multiconjugate adaptive-optics systems that use multiple laser guide stars. These results, combined with the low infrared sky backgrounds, indicate that the Antarctic plateau is the best site on Earth at which to perform high-resolution imaging with large telescopes, either over large fields of view or with appreciable sky coverage. Preliminary site-testing results obtained recently from the Dome Concordia station indicate that this site is far superior to even the South Pole. PMID:15008551

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

    NASA Astrophysics Data System (ADS)

    Sulai, Yusufu N. B.

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

  12. Adaptive compensation for an optical tracking telescope

    NASA Technical Reports Server (NTRS)

    Gilbart, J. W.; Winston, G. C.

    1974-01-01

    The application of model referenced adaptive control theory to an optical tracking telescope is discussed. The capability of the adaptive technique to compensate for mount irregularities such as inertial variations and bearing friction is demonstrated via field test results on a large tracking telescope. Results are presented which show a 6 to 1 improvement in tracking accuracy for a worst-case satellite trajectory.

  13. Optical Profilometers Using Adaptive Signal Processing

    NASA Technical Reports Server (NTRS)

    Hall, Gregory A.; Youngquist, Robert; Mikhael, Wasfy

    2006-01-01

    A method of adaptive signal processing has been proposed as the basis of a new generation of interferometric optical profilometers for measuring surfaces. The proposed profilometers would be portable, hand-held units. Sizes could be thus reduced because the adaptive-signal-processing method would make it possible to substitute lower-power coherent light sources (e.g., laser diodes) for white light sources and would eliminate the need for most of the optical components of current white-light profilometers. The adaptive-signal-processing method would make it possible to attain scanning ranges of the order of decimeters in the proposed profilometers.

  14. Adaptive Optics and NICMOS Uniqueness Space

    SciTech Connect

    Max, C.

    1999-03-22

    As part of the HST Second Decade Study a subgroup consisting of Claire Max, James Beletic, Donald McCarthy, and Keith Noll has analyzed the expected performance of near-infra-red adaptive optics systems on the new generation of 8-10 meter ground-based telescopes, for comparison with HST. In addition the subgroup has polled the adaptive optics community regarding expected adaptive optics performance over the coming five years. Responses have been received from representatives of most of the major telescopes: Gemini, VLT, Keck, LBT, and the MMT, as well as of several operational 3-4 meter telescope AO systems. The present document outlines the conclusions to date, with emphasis on aspects relevant to the NICMOS cryocooler Independent Science Review. In general the near-infra-red capabilities of the new ground-based adaptive optics systems will be complementary to the capabilities of NICMOS. For example NICMOS will have greater H-band sensitivity, broader wavelength coverage, and higher point-spread-function stability, whereas ground-based adaptive optics instruments will have higher spatial and spectral resolution. Section 2 of this report outlines the operational constraints faced by the first generation of adaptive optics (AO) systems on new 8-10 meter telescopes. Section 3 describes the areas of relative strength of near-infra-red observing from the ground via adaptive optics, compared with NICMOS. A Table gives an overview of the main strengths and weaknesses of these current-generation systems. Section 4 gives an indication of ground-based capabilities anticipated in the near future and in five to ten years. Section 5 contains a summary and conclusions.

  15. Optical Computers and Space Technology

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin A.; Frazier, Donald O.; Penn, Benjamin; Paley, Mark S.; Witherow, William K.; Banks, Curtis; Hicks, Rosilen; Shields, Angela

    1995-01-01

    The rapidly increasing demand for greater speed and efficiency on the information superhighway requires significant improvements over conventional electronic logic circuits. Optical interconnections and optical integrated circuits are strong candidates to provide the way out of the extreme limitations imposed on the growth of speed and complexity of nowadays computations by the conventional electronic logic circuits. The new optical technology has increased the demand for high quality optical materials. NASA's recent involvement in processing optical materials in space has demonstrated that a new and unique class of high quality optical materials are processible in a microgravity environment. Microgravity processing can induce improved orders in these materials and could have a significant impact on the development of optical computers. We will discuss NASA's role in processing these materials and report on some of the associated nonlinear optical properties which are quite useful for optical computers technology.

  16. Fiber Optics and Library Technology.

    ERIC Educational Resources Information Center

    Koenig, Michael

    1984-01-01

    This article examines fiber optic technology, explains some of the key terminology, and speculates about the way fiber optics will change our world. Applications of fiber optics to library systems in three major areas--linkage of a number of mainframe computers, local area networks, and main trunk communications--are highlighted. (EJS)

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

    PubMed

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

    Introduction of adaptive optics technology into astronomy and ophthalmology has made great contributions in these fields, allowing one to recover images blurred by atmospheric turbulence or aberrations of the eye. Similar adaptive optics improvement in microscopic imaging is also of interest to researchers using various techniques. Current technology of adaptive optics typically contains three key elements: a wavefront sensor, wavefront corrector, and controller. These hardware elements tend to be bulky, expensive, and limited in resolution, involving, for example, lenslet arrays for sensing or multiactuator deformable mirrors for correcting. We have previously introduced an alternate approach based on unique capabilities of digital holography, namely direct access to the phase profile of an optical field and the ability to numerically manipulate the phase profile. We have also demonstrated that direct access and compensation of the phase profile are possible not only with conventional coherent digital holography, but also with a new type of digital holography using incoherent light: selfinterference incoherent digital holography (SIDH). The SIDH generates a complex—i.e., amplitude plus phase—hologram from one or several interferograms acquired with incoherent light, such as LEDs, lamps, sunlight, or fluorescence. The complex point spread function can be measured using guide star illumination and it allows deterministic deconvolution of the full-field image. We present experimental demonstration of aberration compensation in holographic fluorescence microscopy using SIDH. Adaptive optics by SIDH provides new tools for improved cellular fluorescence microscopy through intact tissue layers or other types of aberrant media. PMID:26146767

  19. Holographic fluorescence microscopy with incoherent digital holographic adaptive optics

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  20. TESTING THE APODIZED PUPIL LYOT CORONAGRAPH ON THE LABORATORY FOR ADAPTIVE OPTICS EXTREME ADAPTIVE OPTICS TESTBED

    SciTech Connect

    Thomas, Sandrine J.; Dillon, Daren; Gavel, Donald; Macintosh, Bruce; Sivaramakrishnan, Anand E-mail: dillon@ucolick.org E-mail: soummer@stsci.edu E-mail: anand@amnh.org

    2011-10-15

    We present testbed results of the Apodized Pupil Lyot Coronagraph (APLC) at the Laboratory for Adaptive Optics (LAO). These results are part of the validation and tests of the coronagraph and of the Extreme Adaptive Optics (ExAO) for the Gemini Planet Imager (GPI). The apodizer component is manufactured with a halftone technique using black chrome microdots on glass. Testing this APLC (like any other coronagraph) requires extremely good wavefront correction, which is obtained to the 1 nm rms level using the microelectricalmechanical systems (MEMS) technology, on the ExAO visible testbed of the LAO at the University of Santa Cruz. We used an APLC coronagraph without central obstruction, both with a reference super-polished flat mirror and with the MEMS to obtain one of the first images of a dark zone in a coronagraphic image with classical adaptive optics using a MEMS deformable mirror (without involving dark hole algorithms). This was done as a complementary test to the GPI coronagraph testbed at American Museum of Natural History, which studied the coronagraph itself without wavefront correction. Because we needed a full aperture, the coronagraph design is very different from the GPI design. We also tested a coronagraph with central obstruction similar to that of GPI. We investigated the performance of the APLC coronagraph and more particularly the effect of the apodizer profile accuracy on the contrast. Finally, we compared the resulting contrast to predictions made with a wavefront propagation model of the testbed to understand the effects of phase and amplitude errors on the final contrast.

  1. Testing the Apodized Pupil Lyot Coronagraph on the Laboratory for Adaptive Optics Extreme Adaptive Optics Testbed

    NASA Astrophysics Data System (ADS)

    Thomas, Sandrine J.; Soummer, Rémi; Dillon, Daren; Macintosh, Bruce; Gavel, Donald; Sivaramakrishnan, Anand

    2011-10-01

    We present testbed results of the Apodized Pupil Lyot Coronagraph (APLC) at the Laboratory for Adaptive Optics (LAO). These results are part of the validation and tests of the coronagraph and of the Extreme Adaptive Optics (ExAO) for the Gemini Planet Imager (GPI). The apodizer component is manufactured with a halftone technique using black chrome microdots on glass. Testing this APLC (like any other coronagraph) requires extremely good wavefront correction, which is obtained to the 1 nm rms level using the microelectricalmechanical systems (MEMS) technology, on the ExAO visible testbed of the LAO at the University of Santa Cruz. We used an APLC coronagraph without central obstruction, both with a reference super-polished flat mirror and with the MEMS to obtain one of the first images of a dark zone in a coronagraphic image with classical adaptive optics using a MEMS deformable mirror (without involving dark hole algorithms). This was done as a complementary test to the GPI coronagraph testbed at American Museum of Natural History, which studied the coronagraph itself without wavefront correction. Because we needed a full aperture, the coronagraph design is very different from the GPI design. We also tested a coronagraph with central obstruction similar to that of GPI. We investigated the performance of the APLC coronagraph and more particularly the effect of the apodizer profile accuracy on the contrast. Finally, we compared the resulting contrast to predictions made with a wavefront propagation model of the testbed to understand the effects of phase and amplitude errors on the final contrast.

  2. Thin nearly wireless adaptive optical device

    NASA Technical Reports Server (NTRS)

    Knowles, Gareth J. (Inventor); Hughes, Eli (Inventor)

    2009-01-01

    A thin nearly wireless adaptive optical device capable of dynamically modulating the shape of a mirror in real time to compensate for atmospheric distortions and/or variations along an optical material is provided. The device includes an optical layer, a substrate, at least one electronic circuit layer with nearly wireless architecture, an array of actuators, power electronic switches, a reactive force element, and a digital controller. Actuators are aligned so that each axis of expansion and contraction intersects both substrate and reactive force element. Electronics layer with nearly wireless architecture, power electronic switches, and digital controller are provided within a thin-film substrate. The size and weight of the adaptive optical device is solely dominated by the size of the actuator elements rather than by the power distribution system.

  3. Thin, nearly wireless adaptive optical device

    NASA Technical Reports Server (NTRS)

    Knowles, Gareth (Inventor); Hughes, Eli (Inventor)

    2008-01-01

    A thin, nearly wireless adaptive optical device capable of dynamically modulating the shape of a mirror in real time to compensate for atmospheric distortions and/or variations along an optical material is provided. The device includes an optical layer, a substrate, at least one electronic circuit layer with nearly wireless architecture, an array of actuators, power electronic switches, a reactive force element, and a digital controller. Actuators are aligned so that each axis of expansion and contraction intersects both substrate and reactive force element. Electronics layer with nearly wireless architecture, power electronic switches, and digital controller are provided within a thin-film substrate. The size and weight of the adaptive optical device is solely dominated by the size of the actuator elements rather than by the power distribution system.

  4. Thin, nearly wireless adaptive optical device

    NASA Technical Reports Server (NTRS)

    Knowles, Gareth (Inventor); Hughes, Eli (Inventor)

    2007-01-01

    A thin, nearly wireless adaptive optical device capable of dynamically modulating the shape of a mirror in real time to compensate for atmospheric distortions and/or variations along an optical material is provided. The device includes an optical layer, a substrate, at least one electronic circuit layer with nearly wireless architecture, an array of actuators, power electronic switches, a reactive force element, and a digital controller. Actuators are aligned so that each axis of expansion and contraction intersects both substrate and reactive force element. Electronics layer with nearly wireless architecture, power electronic switches, and digital controller are provided within a thin-film substrate. The size and weight of the adaptive optical device is solely dominated by the size of the actuator elements rather than by the power distribution system.

  5. Robust Wiener filtering for Adaptive Optics

    SciTech Connect

    Poyneer, L A

    2004-06-17

    In many applications of optical systems, the observed field in the pupil plane has a non-uniform phase component. This deviation of the phase of the field from uniform is called a phase aberration. In imaging systems this aberration will degrade the quality of the images. In the case of a large astronomical telescope, random fluctuations in the atmosphere lead to significant distortion. These time-varying distortions can be corrected using an Adaptive Optics (AO) system, which is a real-time control system composed of optical, mechanical and computational parts. Adaptive optics is also applicable to problems in vision science, laser propagation and communication. For a high-level overview, consult this web site. For an in-depth treatment of the astronomical case, consult these books.

  6. A flexible testbed for adaptive optics in strong turbulence

    NASA Astrophysics Data System (ADS)

    Schmidt, Jason D.; Steinbock, Michael J.; Berg, Eric C.

    2011-06-01

    In recent years, optical wave propagation through strong atmospheric turbulence and adaptive optics compensation thereof has received much attention in literature and technical meetings. At the Air Force Institute of Technology, recent simulation-based efforts in strong turbulence compensation are expanding into laboratory experiments utilizing a versatile surrogate turbulence simulator and adaptive optics system. The system can switch between using two different wavefront sensors, a Shack-Hartmann and a self-referencing interferometer. Wavefront reconstruction takes place on field programmable gate arrays, operating at kilohertz frame rates. Further, the system is able to perform reconstruction and control in software for testing of advanced algorithms (at frame rates below 10 Hz). The entire package is compact enough for transportation to other laboratories and live test facilities. This paper describes the optical layout, architecture, and initial results of real-time operation.

  7. Adaptable Deployable Entry and Placement Technology (ADEPT)

    NASA Video Gallery

    The Adaptable, Deployable Entry Placement Technology (ADEPT) Project will test and demonstrate a deployable aeroshell concept as a viable thermal protection system for entry, descent, and landing o...

  8. Optimized micromirror arrays for adaptive optics

    NASA Astrophysics Data System (ADS)

    Michalicek, M. Adrian; Comtois, John H.; Hetherington, Dale L.

    1999-01-01

    This paper describes the design, layout, fabrication, and surface characterization of highly optimized surface micromachined micromirror devices. Design considerations and fabrication capabilities are presented. These devices are fabricated in the state-of-the-art, four-level, planarized, ultra-low-stress polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology (SUMMiT). This enabling process permits the development of micromirror devices with near-ideal characteristics that have previously been unrealizable in standard three-layer polysilicon processes. The reduced 1 μm minimum feature sizes and 0.1 μm mask resolution make it possible to produce dense wiring patterns and irregularly shaped flexures. Likewise, mirror surfaces can be uniquely distributed and segmented in advanced patterns and often irregular shapes in order to minimize wavefront error across the pupil. The ultra-low-stress polysilicon and planarized upper layer allow designers to make larger and more complex micromirrors of varying shape and surface area within an array while maintaining uniform performance of optical surfaces. Powerful layout functions of the AutoCAD editor simplify the design of advanced micromirror arrays and make it possible to optimize devices according to the capabilities of the fabrication process. Micromirrors fabricated in this process have demonstrated a surface variance across the array from only 2-3 nm to a worst case of roughly 25 nm while boasting active surface areas of 98% or better. Combining the process planarization with a ``planarized-by-design'' approach will produce micromirror array surfaces that are limited in flatness only by the surface deposition roughness of the structural material. Ultimately, the combination of advanced process and layout capabilities have permitted the fabrication of highly optimized micromirror arrays for adaptive optics.

  9. Optical technologies for space sensor

    NASA Astrophysics Data System (ADS)

    Wang, Hu; Liu, Jie; Xue, Yaoke; Liu, Yang; Liu, Meiying; Wang, Lingguang; Yang, Shaodong; Lin, Shangmin; Chen, Su; Luo, Jianjun

    2015-10-01

    Space sensors are used in navigation sensor fields. The sun, the earth, the moon and other planets are used as frame of reference to obtain stellar position coordinates, and then to control the attitude of an aircraft. Being the "eyes" of the space sensors, Optical sensor system makes images of the infinite far stars and other celestial bodies. It directly affects measurement accuracy of the space sensor, indirectly affecting the data updating rate. Star sensor technology is the pilot for Space sensors. At present more and more attention is paid on all-day star sensor technology. By day and night measurements of the stars, the aircraft's attitude in the inertial coordinate system can be provided. Facing the requirements of ultra-high-precision, large field of view, wide spectral range, long life and high reliability, multi-functional optical system, we integration, integration optical sensors will be future space technology trends. In the meantime, optical technologies for space-sensitive research leads to the development of ultra-precision optical processing, optical and precision test machine alignment technology. It also promotes the development of long-life optical materials and applications. We have achieved such absolute distortion better than ±1um, Space life of at least 15years of space-sensitive optical system.

  10. Free Space Optical Communications Utilizing MEMS Adaptive Optics Correction

    SciTech Connect

    Thompson, C A; Kartz, M W; Flath, L M; Wilks, S C; Young, R A; Johnson, G W; Ruggiero, A J

    2002-07-09

    Free space optical communications (FSO) are beginning to provide attractive alternatives to fiber-based solutions in many situations. Currently, a handful of companies provide fiberless alternatives specifically aimed at corporate intranet and sporting event video applications. These solutions are geared toward solving the ''last mile'' connectivity issues. There exists a potential need to extend this pathlength to distances much greater than a 1 km, particularly for government and military applications. For cases of long distance optical propagation, atmospheric turbulence will ultimately limit the maximum achievable data rate. In this paper, we propose a method to improve signal quality through the use of adaptive optics. In particular, we show work in progress toward a high-speed, small footprint Adaptive Optics system for horizontal and slant path laser communications. Such a system relies heavily on recent progress in Micro-Electro-Mechanical Systems (MEMS) deformable mirrors, as well as improved communication and computational components.

  11. Adaptive-clustering optical neural net.

    PubMed

    Casasent, D P; Barnard, E

    1990-06-10

    Pattern recognition techniques (for clustering and linear discriminant function selection) are combined with neural net methods (that provide an automated method to combine linear discriminant functions into piecewise linear discriminant surfaces). The resulting adaptive-clustering neural net is suitable for optical implementation and has certain desirable properties in comparison with other neural nets. Simulation results are provided.

  12. Extragalactic Fields Optimized for Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Damjanov, Ivana; Abraham, Roberto G.; Glazebrook, Karl; McGregor, Peter; Rigaut, Francois; McCarthy, Patrick J.; Brinchmann, Jarle; Cuillandre, Jean-Charles; Mellier, Yannick; McCracken, Henry Joy; Hudelot, Patrick; Monet, David

    2011-03-01

    In this article we present the coordinates of 67 55' × 55' patches of sky that have the rare combination of both high stellar surface density (>=0.5 arcmin-2 with 13 < R < 16.5 mag) and low extinction (E(B - V)<=0.1). These fields are ideal for adaptive-optics-based follow-up of extragalactic targets. One region of sky, situated near Baade's Window, contains most of the patches we have identified. Our optimal field, centered at R.A.: 7h24m3s, decl.: -1°27'15'', has an additional advantage of being accessible from both hemispheres. We propose a figure of merit for quantifying real-world adaptive optics performance and use this to analyze the performance of multiconjugate adaptive optics in these fields. We also compare our results with those that would be obtained in existing deep fields. In some cases adaptive optics observations undertaken in the fields given in this article would be orders of magnitude more efficient than equivalent observations undertaken in existing deep fields.

  13. Holographic fluorescence microscopy with incoherent digital holographic adaptive optics

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  14. Characterization and Operation of Liquid Crystal Adaptive Optics Phoropter

    SciTech Connect

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

    2003-02-05

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

  15. Teaching Optics and Systems Engineering With Adaptive Optics Workbenches

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Luo, Qi; Luo, Xi; Li, Xinyang

    2016-04-01

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

  17. Adaptive holography for optical sensing applications

    NASA Astrophysics Data System (ADS)

    Residori, S.; Bortolozzo, U.; Peigné, A.; Molin, S.; Nouchi, P.; Dolfi, D.; Huignard, J. P.

    2016-03-01

    Adaptive holography is a promising method for high sensitivity phase modulation measurements in the presence of slow perturbations from the environment. The technique is based on the use of a nonlinear recombining medium, here an optically addressed spatial light modulator specifically realized to operate at 1.55 μm. Owing to the physical mechanisms involved, the interferometer adapts to slow phase variations within a range of 5-10 Hz, thus filtering out low frequency noise while transmitting higher frequency phase modulations. We present the basic principles of the adaptive interferometer and show that it can be used in association with a sensing fiber in order to detect phase modulations. Finally, a phase-OTDR architecture using the adaptive holographic interferometer is presented and shown to allows the detection of localized perturbations along the sensing fiber.

  18. Adaptive optics assisted Fourier domain OCT with balanced detection

    NASA Astrophysics Data System (ADS)

    Meadway, A.; Bradu, A.; Hathaway, M.; Van der Jeught, S.; Rosen, R. B.; Podoleanu, A. Gh.

    2011-03-01

    Two factors are of importance to optical coherence tomography (OCT), resolution and sensitivity. Adaptive optics improves the resolution of a system by correcting for aberrations causing distortions in the wave-front. Balanced detection has been used in time domain OCT systems by removing excess photon noise, however it has not been used in Fourier domain systems, as the cameras used in the spectrometers saturated before excess photon noise becomes a problem. Advances in camera technology mean that this is no longer the case and balanced detection can now be used to improve the signal to noise ratio in a Fourier domain (FD) OCT system. An FD-OCT system, enhanced with adaptive optics, is presented and is used to show the improvement that balanced detection can provide. The signal to noise ratios of single camera detection and balanced detection are assessed and in-vivo retinal images are acquired to demonstrate better image quality when using balance detection.

  19. Lens based adaptive optics scanning laser ophthalmoscope.

    PubMed

    Felberer, Franz; Kroisamer, Julia-Sophie; Hitzenberger, Christoph K; Pircher, Michael

    2012-07-30

    We present an alternative approach for an adaptive optics scanning laser ophthalmoscope (AO-SLO). In contrast to other commonly used AO-SLO instruments, the imaging optics consist of lenses. Images of the fovea region of 5 healthy volunteers are recorded. The system is capable to resolve human foveal cones in 3 out of 5 healthy volunteers. Additionally, we investigated the capability of the system to support larger scanning angles (up to 5°) on the retina. Finally, in order to demonstrate the performance of the instrument images of rod photoreceptors are presented.

  20. Adaptive optics without guide stars (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Mertz, Jerome; Li, Jiang; Beaulieu, Devin; Paudel, Hari P.; Barankov, Roman; Bifano, Thomas G.

    2016-03-01

    Adaptive optics is a strategy to compensate for sample-induced aberrations in microscopy applications. Generally, it requires the presence of "guide stars" in the sample to serve as localized reference targets. We describe an implementation of conjugate adaptive optics that is amenable to widefield (i.e. non-scanning) microscopy, and can provide aberration corrections over potentially large fields of view without the use of guide stars. A unique feature of our implementation is that it is based on wavefront sensing with a single-shot partitioned-aperture sensor that provides large dynamic range compatible with extended samples. Combined information provided by this sensor and the imaging camera enable robust image de-blurring based on a rapid estimation of sample and aberrations obtained by closed-loop feedback. We present the theoretical principle of our technique and experimental demonstrations using both trans-illumination and fluorescence microscopes. Finally, we apply our technique to mouse brain imaging.

  1. HIGH-EFFICIENCY AUTONOMOUS LASER ADAPTIVE OPTICS

    SciTech Connect

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

    2014-07-20

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

  2. Adaptive Optics Imaging of Solar System Objects

    NASA Technical Reports Server (NTRS)

    Roddier, Francois; Owen, Toby

    1997-01-01

    Most solar system objects have never been observed at wavelengths longer than the R band with an angular resolution better than 1 sec. The Hubble Space Telescope itself has only recently been equipped to observe in the infrared. However, because of its small diameter, the angular resolution is lower than that one can now achieved from the ground with adaptive optics, and time allocated to planetary science is limited. We have been using adaptive optics (AO) on a 4-m class telescope to obtain 0.1 sec resolution images solar system objects at far red and near infrared wavelengths (0.7-2.5 micron) which best discriminate their spectral signatures. Our efforts has been put into areas of research for which high angular resolution is essential, such as the mapping of Titan and of large asteroids, the dynamics and composition of Neptune stratospheric clouds, the infrared photometry of Pluto, Charon, and close satellites previously undetected from the ground.

  3. Adaptive Optics Imaging of Solar System Objects

    NASA Technical Reports Server (NTRS)

    Roddier, Francois; Owen, Toby

    1999-01-01

    Most solar system objects have never been observed at wavelengths longer than the R band with an angular resolution better than 1". The Hubble Space Telescope itself has only recently been equipped to observe in the infrared. However, because of its small diameter, the angular resolution is lower than that one can now achieved from the ground with adaptive optics, and time allocated to planetary science is limited. We have successfully used adaptive optics on a 4-m class telescope to obtain 0.1" resolution images of solar system objects in the far red and near infrared (0.7-2.5 microns), aE wavelengths which best discl"lmlnate their spectral signatures. Our efforts have been put into areas of research for which high angular resolution is essential.

  4. Adaptive optics for improved retinal surgery and diagnostics

    SciTech Connect

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

    2000-08-21

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

  5. Thermo-optically driven adaptive mirror

    NASA Astrophysics Data System (ADS)

    Reinert, Felix; Lüthy, Willy

    2006-02-01

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

  6. Performance of a MEMS-base Adaptive Optics Optical Coherency Tomography System

    SciTech Connect

    Evans, J; Zadwadzki, R J; Jones, S; Olivier, S; Opkpodu, S; Werner, J S

    2008-01-16

    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. Optical Property Analyses of Plant Cells for Adaptive Optics Microscopy

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  8. Robotic visible-light laser adaptive optics

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  9. Adaptive optics retinal imaging: emerging clinical applications.

    PubMed

    Godara, Pooja; Dubis, Adam M; Roorda, Austin; Duncan, Jacque L; Carroll, Joseph

    2010-12-01

    The human retina is a uniquely accessible tissue. Tools like scanning laser ophthalmoscopy and spectral domain-optical coherence tomography provide clinicians with remarkably clear pictures of the living retina. Although the anterior optics of the eye permit such non-invasive visualization of the retina and associated pathology, the same optics induce significant aberrations that obviate cellular-resolution imaging in most cases. Adaptive optics (AO) imaging systems use active optical elements to compensate for aberrations in the optical path between the object and the camera. When applied to the human eye, AO allows direct visualization of individual rod and cone photoreceptor cells, retinal pigment epithelium cells, and white blood cells. AO imaging has changed the way vision scientists and ophthalmologists see the retina, helping to clarify our understanding of retinal structure, function, and the etiology of various retinal pathologies. Here, we review some of the advances that were made possible with AO imaging of the human retina and discuss applications and future prospects for clinical imaging.

  10. Compact adaptive optics line scanning ophthalmoscope

    PubMed Central

    Mujat, Mircea; Ferguson, R. Daniel; Iftimia, Nicusor; Hammer, Daniel X.

    2010-01-01

    We have developed a compact retinal imager that integrates adaptive optics (AO) into a line scanning ophthalmoscope (LSO). The bench-top AO-LSO instrument significantly reduces the size, complexity, and cost of research AO scanning laser ophthalmoscopes (AOSLOs), for the purpose of moving adaptive optics imaging more rapidly into routine clinical use. The AO-LSO produces high resolution retinal images with only one moving part and a significantly reduced instrument footprint and number of optical components. The AO-LSO has a moderate field of view (5.5 deg), which allows montages of the macula or other targets to be obtained more quickly and efficiently. In a preliminary human subjects investigation, photoreceptors could be resolved and counted within ~0.5 mm of the fovea. Photoreceptor counts matched closely to previously reported histology. The capillaries surrounding the foveal avascular zone could be resolved, as well as cells flowing within them. Individual nerve fiber bundles could be resolved, especially near the optic nerve head, as well as other structures such as the lamina cribrosa. In addition to instrument design, fabrication, and testing, software algorithms were developed for automated image registration and cone counting. PMID:19506678

  11. Adaptive optics scanning ophthalmoscopy with annular pupils.

    PubMed

    Sulai, Yusufu N; Dubra, Alfredo

    2012-07-01

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

  12. Adaptive Technologies for Training and Education

    ERIC Educational Resources Information Center

    Durlach, Paula J., Ed; Lesgold, Alan M., Ed.

    2012-01-01

    This edited volume provides an overview of the latest advancements in adaptive training technology. Intelligent tutoring has been deployed for well-defined and relatively static educational domains such as algebra and geometry. However, this adaptive approach to computer-based training has yet to come into wider usage for domains that are less…

  13. The CHARA Array Adaptive Optics Program

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  14. The ESO Adaptive Optics Facility under Test

    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.

  15. Adaptive optics at the IOE, CAS

    NASA Astrophysics Data System (ADS)

    Jiang, Wenhan; Rao, Changhui; Zhang, Yudong; Ling, Ning; Guan, Chunlin

    2009-02-01

    R&D on Adaptive Optics in the Institute of Optics & Electronics (IOE), Chinese Academy of Sciences (CAS) began in 1979. In this paper, several recent achievements will be reported: 1. AO for astronomical telescopes. AO system for 1.2 m telescope at Yunnan Astronomical Observatory was built in 1998. It was updated in 2004, and high resolution images approaching diffraction limit were obtained. A new AO telescope with 1.8m aperture is being built, and a 4m AO telescope is being planned. 2. AO for ICF facility. A 19-element AO system with hill-climbing control algorithm for "Shenguang I" ICF facility was built in 1985, which was the first AO system used in ICF facility in the world. A set of 8 AO systems was installed in a bundle of ICF prototype for "Shenguang III" ICF facility. A new system is being built for further development of ICF facility. 3. AO for retinal imaging. In 1999, the first AO system with 19-element DM was built for retinal imaging. Several AO systems with 37-element deformable mirror (DM) were built and used for vision research and clinical inspection. It is being integrated with an OCT system for high resolution retinal imaging. All of the main subsystems, such as DMs, wavefront sensors, and high speed processors, were built in the Laboratory on Adaptive Optics of IOE, CAS.

  16. Adaptive Optics Imaging in Laser Pointer Maculopathy.

    PubMed

    Sheyman, Alan T; Nesper, Peter L; Fawzi, Amani A; Jampol, Lee M

    2016-08-01

    The authors report multimodal imaging including adaptive optics scanning laser ophthalmoscopy (AOSLO) (Apaeros retinal image system AOSLO prototype; Boston Micromachines Corporation, Boston, MA) in a case of previously diagnosed unilateral acute idiopathic maculopathy (UAIM) that demonstrated features of laser pointer maculopathy. The authors also show the adaptive optics images of a laser pointer maculopathy case previously reported. A 15-year-old girl was referred for the evaluation of a maculopathy suspected to be UAIM. The authors reviewed the patient's history and obtained fluorescein angiography, autofluorescence, optical coherence tomography, infrared reflectance, and AOSLO. The time course of disease and clinical examination did not fit with UAIM, but the linear pattern of lesions was suspicious for self-inflicted laser pointer injury. This was confirmed on subsequent questioning of the patient. The presence of linear lesions in the macula that are best highlighted with multimodal imaging techniques should alert the physician to the possibility of laser pointer injury. AOSLO further characterizes photoreceptor damage in this condition. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:782-785.]. PMID:27548458

  17. Adaptive Optics Imaging in Laser Pointer Maculopathy.

    PubMed

    Sheyman, Alan T; Nesper, Peter L; Fawzi, Amani A; Jampol, Lee M

    2016-08-01

    The authors report multimodal imaging including adaptive optics scanning laser ophthalmoscopy (AOSLO) (Apaeros retinal image system AOSLO prototype; Boston Micromachines Corporation, Boston, MA) in a case of previously diagnosed unilateral acute idiopathic maculopathy (UAIM) that demonstrated features of laser pointer maculopathy. The authors also show the adaptive optics images of a laser pointer maculopathy case previously reported. A 15-year-old girl was referred for the evaluation of a maculopathy suspected to be UAIM. The authors reviewed the patient's history and obtained fluorescein angiography, autofluorescence, optical coherence tomography, infrared reflectance, and AOSLO. The time course of disease and clinical examination did not fit with UAIM, but the linear pattern of lesions was suspicious for self-inflicted laser pointer injury. This was confirmed on subsequent questioning of the patient. The presence of linear lesions in the macula that are best highlighted with multimodal imaging techniques should alert the physician to the possibility of laser pointer injury. AOSLO further characterizes photoreceptor damage in this condition. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:782-785.].

  18. Technology reviews: Daylighting optical systems

    SciTech Connect

    Schuman, J.; Rubinstein, F.; Papamichael, K.; Beltran, L.; Lee, E.S.; Selkowitz, S.

    1992-09-01

    We present a representative review of existing, emerging, and future technology options in each of five hardware and systems areas in envelope and lighting technologies: lighting systems, glazing systems, shading systems, daylighting optical systems, and dynamic curtain wall systems. The term technology is used here to describe any design choice for energy efficiency, ranging from individual components to more complex systems to general design strategies. The purpose of this task is to characterize the state of the art in envelope and lighting technologies in order to identify those with promise for advanced integrated systems, with an emphasis on California commercial buildings. For each technology category, the following activities have been attempted to the extent possible: Identify key performance characteristics and criteria for each technology. Determine the performance range of available technologies. Identify the most promising technologies and promising trends in technology advances. Examine market forces and market trends.Develop a continuously growing in-house database to be used throughout the project. A variety of information sources have been used in these technology characterizations, including miscellaneous periodicals, manufacturer catalogs and cut sheets, other research documents, and data from previous computer simulations. We include these different sources in order to best show the type and variety of data available, however publication here does not imply our guarantee of these data. Within each category, several broad classes are identified, and within each class we examine the generic individual technologies that fall into that class.

  19. Adaptive Holographic Fiber-Optic Interferometer

    NASA Astrophysics Data System (ADS)

    Kozhevnikov, Nikolai M.; Lipovskaya, Margarita J.

    1990-04-01

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

  20. Characterization of Adaptive Optics at Keck Observatory

    SciTech Connect

    van Dam, M A; Macintosh, B A

    2003-07-24

    In this paper, the adaptive optics (AO) system at Keck Observatory is characterized. The AO system is described in detail. The physical parameters of the lenslets, CCD and deformable mirror, the calibration procedures and the signal processing algorithms are explained. Results of sky performance tests are presented: the AO system is shown to deliver images with an average Strehl ratio of up to 0.37 at 1.59 {micro}m using a bright guide star. An error budget that is consistent with the observed image quality is presented.

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

    SciTech Connect

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

    2006-01-05

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

  2. Optical Design for Extremely Large Telescope Adaptive Optics Systems

    SciTech Connect

    Bauman, B J

    2003-11-26

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

  3. Optical technology for flight control systems

    NASA Technical Reports Server (NTRS)

    Mayanagi, M.

    1986-01-01

    Optical applications to the flight control system including optical data bus, sensors, and transducers are analyzed. Examples of optical data bus include airborne light optical fiber technology (ALOFT), F-5E, YA-7D, MIL-STD-1553 fiber optic data bus and NAL-optic data bus. This NAL-optic data bus is applied to STOL, and its characteristics are stressed. Principles and advantages of optical pulse-digital transducers are discussed.

  4. Large aperture adaptive optics for intense lasers

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    ISP SYSTEM has developed a range of large aperture electro-mechanical deformable mirrors (DM) suitable for ultra short pulsed intense lasers. The design of the MD-AME deformable mirror is based on force application on numerous locations thanks to electromechanical actuators driven by stepper motors. DM design and assembly method have been adapted to large aperture beams and the performances were evaluated on a first application for a beam with a diameter of 250mm at 45° angle of incidence. A Strehl ratio above 0.9 was reached for this application. Simulations were correlated with measurements on optical bench and the design has been validated by calculation for very large aperture (up to Ø550mm). Optical aberrations up to Zernike order 5 can be corrected with a very low residual error as for actual MD-AME mirror. Amplitude can reach up to several hundreds of μm for low order corrections. Hysteresis is lower than 0.1% and linearity better than 99%. Contrary to piezo-electric actuators, the μ-AME actuators avoid print-through effects and they permit to keep the mirror shape stable even unpowered, providing a high resistance to electro-magnetic pulses. The MD-AME mirrors can be adapted to circular, square or elliptical beams and they are compatible with all dielectric or metallic coatings.

  5. Kalman filter based control for Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Petit, Cyril; Quiros-Pacheco, Fernando; Conan, Jean-Marc; Kulcsár, Caroline; Raynaud, Henri-François; Fusco, Thierry

    2004-12-01

    Classical Adaptive Optics suffer from a limitation of the corrected Field Of View. This drawback has lead to the development of MultiConjugated Adaptive Optics. While the first MCAO experimental set-ups are presently under construction, little attention has been paid to the control loop. This is however a key element in the optimization process especially for MCAO systems. Different approaches have been proposed in recent articles for astronomical applications : simple integrator, Optimized Modal Gain Integrator and Kalman filtering. We study here Kalman filtering which seems a very promising solution. Following the work of Brice Leroux, we focus on a frequential characterization of kalman filters, computing a transfer matrix. The result brings much information about their behaviour and allows comparisons with classical controllers. It also appears that straightforward improvements of the system models can lead to static aberrations and vibrations filtering. Simulation results are proposed and analysed thanks to our frequential characterization. Related problems such as model errors, aliasing effect reduction or experimental implementation and testing of Kalman filter control loop on a simplified MCAO experimental set-up could be then discussed.

  6. The Giant Magellan Telescope adaptive optics program

    NASA Astrophysics Data System (ADS)

    Bouchez, Antonin H.; Acton, D. Scott; Agapito, Guido; Arcidiacono, Carmelo; Bennet, Francis; Biliotti, Valdemaro; Bonaglia, Marco; Briguglio, Runa; Brusa-Zappellini, Guido; Busoni, Lorenzo; Carbonaro, Luca; Codona, Johanan L.; Conan, Rodolphe; Connors, Thomas; Durney, Oliver; Espeland, Brady; Esposito, Simone; Fini, Luca; Gardhouse, Rusty; Gauron, Thomas M.; Hart, Michael; Hinz, Philip M.; Kanneganti, Srikrishna; Kibblewhite, Edward J.; Knox, Russell P.; McLeod, Brian A.; McMahon, Thomas; Montoya, Manny; Norton, Timothy J.; Ordway, Mark P.; d'Orgeville, Celine; Parcell, Simon; Piatrou, Piotr K.; Pinna, Enrico; Price, Ian; Puglisi, Alfio; Quiros-Pacheco, Fernando; Riccardi, Armando; Roll, John B.; Trancho, Gelys; Uhlendorf, Kristina; Vaitheeswaran, Vidhya; van Dam, Marcos A.; Weaver, David; Xompero, Marco

    2012-07-01

    The Giant Magellan Telescope adaptive optics system will be an integral part of the telescope, providing laser guide star generation, wavefront sensing, and wavefront correction to most of the currently envisioned instruments. The system will provide three observing modes: Natural Guidestar AO (NGSAO), Laser Tomography AO (LTAO), and Ground Layer AO (GLAO). Every AO observing mode will use the telescope’s segmented adaptive secondary mirror to deliver a corrected beam directly to the instruments. High-order wavefront sensing for the NGSAO and LTAO modes is provided by a set of wavefront sensors replicated for each instrument and fed by visible light reflected off the cryostat window. An infrared natural guidestar wavefront sensor with open-loop AO correction is also required to sense tip-tilt, focus, segment piston, and dynamic calibration errors in the LTAO mode. GLAO mode wavefront sensing is provided by laser guidestars over a ~5 arcminute field of view, and natural guidestars over wider fields. A laser guidestar facility will project 120 W of 589 nm laser light in 6 beacons from the periphery of the primary mirror. An off-axis phasing camera and primary and secondary mirror metrology systems will ensure that the telescope optics remain phased. We describe the system requirements, overall architecture, and innovative solutions found to the challenges presented by high-order AO on a segmented extremely large telescope. Further details may be found in specific papers on each of the observing modes and major subsystems.

  7. Extreme Adaptive Optics Planet Imager: XAOPI

    SciTech Connect

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

    2003-09-17

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

  8. Approach for reconstructing anisoplanatic adaptive optics images.

    PubMed

    Aubailly, Mathieu; Roggemann, Michael C; Schulz, Timothy J

    2007-08-20

    Atmospheric turbulence corrupts astronomical images formed by ground-based telescopes. Adaptive optics systems allow the effects of turbulence-induced aberrations to be reduced for a narrow field of view corresponding approximately to the isoplanatic angle theta(0). For field angles larger than theta(0), the point spread function (PSF) gradually degrades as the field angle increases. We present a technique to estimate the PSF of an adaptive optics telescope as function of the field angle, and use this information in a space-varying image reconstruction technique. Simulated anisoplanatic intensity images of a star field are reconstructed by means of a block-processing method using the predicted local PSF. Two methods for image recovery are used: matrix inversion with Tikhonov regularization, and the Lucy-Richardson algorithm. Image reconstruction results obtained using the space-varying predicted PSF are compared to space invariant deconvolution results obtained using the on-axis PSF. The anisoplanatic reconstruction technique using the predicted PSF provides a significant improvement of the mean squared error between the reconstructed image and the object compared to the deconvolution performed using the on-axis PSF. PMID:17712366

  9. Performance of adaptive optics at Lick Observatory

    SciTech Connect

    Olivier, S.S.; An, J.; Avicola, K.

    1994-03-01

    A prototype adaptive optics system has been developed at Lawrence Livermore National Laboratory (LLNL) for use at Lick Observatory. This system is based on an ITEX 69-actuator continuous-surface deformable mirror, a Kodak fast-framing intensified CCD camera, and a Mercury VME board containing four Intel i860 processors. The system has been tested using natural reference stars on the 40-inch Nickel telescope at Lick Observatory yielding up to a factor of 10 increase in image peak intensity and a factor of 6 reduction in image full width at half maximum (FWHM). These results are consistent with theoretical expectations. In order to improve performance, the intensified CCD camera will be replaced by a high-quantum-efficiency low-noise fast CCD camera built for LLNL by Adaptive Optics Associates using a chip developed by Lincoln Laboratory, and the 69-actuator deformable mirror will be replaced by a 127-actuator deformable mirror developed at LLNL. With these upgrades, the system should perform well in median seeing conditions on the 120-inch Shane telescope for observing wavelengths longer than {approximately}1 {mu}m and using natural reference stars brighter than m{sub R} {approximately} 10 or using the laser currently being developed at LLNL for use at Lick Observatory to generate a sodium-layer reference star.

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

    SciTech Connect

    Bissinger, H.

    1994-11-15

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

  11. Object-oriented Matlab adaptive optics toolbox

    NASA Astrophysics Data System (ADS)

    Conan, R.; Correia, C.

    2014-08-01

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

  12. Optical disk technology and information.

    PubMed

    Goldstein, C M

    1982-02-12

    The optical video disk, spawned by the home entertainment industry, and its counterpart, the optical digital disk, both hold great promise for information storage and retrieval and the scientific enterprise. Optical digital disks for computer mass storage are currently under development by many firms. In addition, efforts are under way to allow encoding of digital information on video disks. This is desirable as an inexpensive publication medium for machine-readable data as well as a means of obtaining both video and digital information on one disk. Potential applications of this technology include inexpensive on-line storage, random access graphics to complement on-line information systems, hybrid network architectures, office automation systems, and archival storage.

  13. Performance of the Gemini Planet Imager's adaptive optics system.

    PubMed

    Poyneer, Lisa A; Palmer, David W; Macintosh, Bruce; Savransky, Dmitry; Sadakuni, Naru; Thomas, Sandrine; Véran, Jean-Pierre; Follette, Katherine B; Greenbaum, Alexandra Z; Ammons, S Mark; Bailey, Vanessa P; Bauman, Brian; Cardwell, Andrew; Dillon, Daren; Gavel, Donald; Hartung, Markus; Hibon, Pascale; Perrin, Marshall D; Rantakyrö, Fredrik T; Sivaramakrishnan, Anand; Wang, Jason J

    2016-01-10

    The Gemini Planet Imager's adaptive optics (AO) subsystem was designed specifically to facilitate high-contrast imaging. A definitive description of the system's algorithms and technologies as built is given. 564 AO telemetry measurements from the Gemini Planet Imager Exoplanet Survey campaign are analyzed. The modal gain optimizer tracks changes in atmospheric conditions. Science observations show that image quality can be improved with the use of both the spatially filtered wavefront sensor and linear-quadratic-Gaussian control of vibration. The error budget indicates that for all targets and atmospheric conditions AO bandwidth error is the largest term.

  14. Polygram technology in optical security

    NASA Astrophysics Data System (ADS)

    Girnyk, Vladimir I.; Grygoruk, Valeriy I.; Borisov, Ilya S.

    2004-06-01

    In the context of the paper there are represented the theoretical foundations and technological aspects of creation of the Optical Security Devices by Polygram technology. This technology implies the images of different types combining. There are generally discussed the Computer-Generated Rainbow Holograms (CGRHs) of 3D images. This type of holographic images is distinguished by its reliability against counterfeit, caused by the fact it requires matchless in this field precision of printing system, using extreme for the Electron Beam Lithography Equipment, which is applied for the recording, values of the stamp sizes. On the other hand CGRHs certainly distinguish from similar optical and stereographic images, so they can be easy recognized on the visual level of the verification and don"t need application of any tools. The theoretical basis of the CGRHs creation is strictly presented in this paper. The special attention is paid to the right choice of the non-linear quantization parameters. This paper is mainly concentrated on the investigation of the CGRH combining both with another CGRHs and with the other different images implying by the Polygram technology. The methods of the space restriction of the separate CGRH topology with the information loss and without it are compared. There are carried out the investigations of the influence of the additional images on visual perception of the CGRH.

  15. Adaptive Optics Imaging and Spectroscopy of Neptune

    NASA Technical Reports Server (NTRS)

    Johnson, Lindley (Technical Monitor); Sromovsky, Lawrence A.

    2005-01-01

    OBJECTIVES: We proposed to use high spectral resolution imaging and spectroscopy of Neptune in visible and near-IR spectral ranges to advance our understanding of Neptune s cloud structure. We intended to use the adaptive optics (AO) system at Mt. Wilson at visible wavelengths to try to obtain the first groundbased observations of dark spots on Neptune; we intended to use A 0 observations at the IRTF to obtain near-IR R=2000 spatially resolved spectra and near-IR A0 observations at the Keck observatory to obtain the highest spatial resolution studies of cloud feature dynamics and atmospheric motions. Vertical structure of cloud features was to be inferred from the wavelength dependent absorption of methane and hydrogen,

  16. Durham adaptive optics real-time controller.

    PubMed

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

    2010-11-10

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

  17. Wavefront Control for Extreme Adaptive Optics

    SciTech Connect

    Poyneer, L A

    2003-07-16

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

  18. Adaptive optics optical coherence tomography at 1 MHz.

    PubMed

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

    2014-12-01

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

  19. Adaptive optics without altering visual perception.

    PubMed

    Koenig, D E; Hart, N W; Hofer, H J

    2014-04-01

    Adaptive optics combined with visual psychophysics creates the potential to study the relationship between visual function and the retina at the cellular scale. This potential is hampered, however, by visual interference from the wavefront-sensing beacon used during correction. For example, we have previously shown that even a dim, visible beacon can alter stimulus perception (Hofer et al., 2012). Here we describe a simple strategy employing a longer wavelength (980nm) beacon that, in conjunction with appropriate restriction on timing and placement, allowed us to perform psychophysics when dark adapted without altering visual perception. The method was verified by comparing detection and color appearance of foveally presented small spot stimuli with and without the wavefront beacon present in 5 subjects. As an important caution, we found that significant perceptual interference can occur even with a subliminal beacon when additional measures are not taken to limit exposure. Consequently, the lack of perceptual interference should be verified for a given system, and not assumed based on invisibility of the beacon.

  20. Adaptive Detector Arrays for Optical Communications Receivers

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V.; Srinivasan, M.

    2000-01-01

    The structure of an optimal adaptive array receiver for ground-based optical communications is described and its performance investigated. Kolmogorov phase screen simulations are used to model the sample functions of the focal-plane signal distribution due to turbulence and to generate realistic spatial distributions of the received optical field. This novel array detector concept reduces interference from background radiation by effectively assigning higher confidence levels at each instant of time to those detector elements that contain significant signal energy and suppressing those that do not. A simpler suboptimum structure that replaces the continuous weighting function of the optimal receiver by a hard decision on the selection of the signal detector elements also is described and evaluated. Approximations and bounds to the error probability are derived and compared with the exact calculations and receiver simulation results. It is shown that, for photon-counting receivers observing Poisson-distributed signals, performance improvements of approximately 5 dB can be obtained over conventional single-detector photon-counting receivers, when operating in high background environments.

  1. Closed-loop adaptive optics using a CMOS image quality metric sensor

    NASA Astrophysics Data System (ADS)

    Ting, Chueh; Rayankula, Aditya; Giles, Michael K.; Furth, Paul M.

    2006-08-01

    When compared to a Shack-Hartmann sensor, a CMOS image sharpness sensor has the advantage of reduced complexity in a closed-loop adaptive optics system. It also has the potential to be implemented as a smart sensor using VLSI technology. In this paper, we present a novel adaptive optics testbed that uses a CMOS sharpness imager built in the New Mexico State University (NMSU) Electro-Optics Research Laboratory (EORL). The adaptive optics testbed, which includes a CMOS image quality metric sensor and a 37-channel deformable mirror, has the capability to rapidly compensate higher-order phase aberrations. An experimental performance comparison of the pinhole image sharpness feedback method and the CMOS imager is presented. The experimental data shows that the CMOS sharpness imager works well in a closed-loop adaptive optics system. Its overall performance is better than that of the pinhole method, and it has a fast response time.

  2. Development of China's fiber optic technology discussed

    NASA Astrophysics Data System (ADS)

    Bai, Q.

    1986-04-01

    Fiber optic technology is a new transmission technology having the outstanding advantages of low loss, high capacity, no magnetic interference, all-dielectric transmission, small size, and light weight. Research into fiber optic technology began in the mid-1970's in China. The scope of applications for fiber optic communications systems is divided into three categories: junction lines, trunk lines, and subscriber lines. Each of the categories are briefly discussed. The advantages and economic suitability of fiber optics are discussed.

  3. Extreme Adaptive Optics Testbed: Results and Future Work

    SciTech Connect

    Evans, J W; Sommargren, G; Poyneer, L; Macintosh, B; Severson, S; Dillon, D; Sheinis, A; Palmer, D; Kasdin, J; Olivier, S

    2004-07-15

    'Extreme' adaptive optics systems are optimized for ultra-high-contrast applications, such as ground-based extrasolar planet detection. 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 simple optical design allows us to minimize wavefront error and maximize the experimentally achievable contrast before progressing to a more complex set-up. A phase shifting diffraction interferometer is used to measure wavefront errors with sub-nm precision and accuracy. We have demonstrated RMS wavefront errors of <1.3 nm and a contrast of >10{sup -7} over a substantial region using a shaped pupil. Current work includes the installation and characterization of a 1024-actuator Micro-Electro-Mechanical- Systems (MEMS) deformable mirror, manufactured by Boston Micro-Machines, which will be used for wavefront control. In our initial experiments we can flatten the deformable mirror to 1.8-nm RMS wavefront error within a control radius of 5-13 cycles per aperture. Ultimately this testbed will be used to test all aspects of the system architecture for an extrasolar planet-finding AO system.

  4. Analysis of optical wavefront reconstruction and deconvolution in adaptive optics

    NASA Astrophysics Data System (ADS)

    Luke, David Russell

    2001-11-01

    It was in the spirit of ``reuniting divergent trends by clarifying the common features and interconnections of many distinct and diverse scientific facts'' that Courant and Hilbert published their book Methods of Mathematical Physics [43]. This thesis is written in the same spirit and with the same goal. We focus our attention on the problem of wavefront reconstruction and deconvolution in adaptive optics. This is an ill-posed, non-linear inverse problem that touches on the theory of harmonic analysis, variational analysis, signal processing, nonconvex optimization, regularization, statistics and probability. Numerical solutions rely on spectral and operator-splitting methods as well as limited memory and multi-resolution techniques. We introduce novel methods for wavefront reconstruction and compare our results against common techniques. Previous work on this problem is reviewed and unified in a non-parametric, analytic framework.

  5. Liquid-crystal prisms for tip-tilt adaptive optics.

    PubMed

    Love, G D; Major, J V; Purvis, A

    1994-08-01

    Results from an electrically addressed liquid-crystal cell producing continuous phase profiles are presented. The adaptive deflection of a beam of light for use in a tip-tilt adaptive optics system is demonstrated. We compare the optical performance of liquid-crystal prisms with experimental data on atmospheric seeing at the William Herschel Telescope.

  6. Liquid-crystal prisms for tip-tilt adaptive optics.

    PubMed

    Love, G D; Major, J V; Purvis, A

    1994-08-01

    Results from an electrically addressed liquid-crystal cell producing continuous phase profiles are presented. The adaptive deflection of a beam of light for use in a tip-tilt adaptive optics system is demonstrated. We compare the optical performance of liquid-crystal prisms with experimental data on atmospheric seeing at the William Herschel Telescope. PMID:19844566

  7. Silica optical fibers: technology update

    NASA Astrophysics Data System (ADS)

    Krohn, David A.; McCann, Brian P.

    1995-05-01

    Silica-core optical fibers have long been the standard delivery medium for medical laser delivery systems. Their high strength, excellent flexibility, and low cost continue to make them the fiber of choice for systems operating from 300 to 2200 nm. An overview of the current fiber constructions available to the industry is reviewed. Silicone-clad fibers, hard- fluoropolymer clad fibers and silica-clad fibers are briefly compared in terms of mechanical and optical properties. The variety of fiber coatings available is also discussed. A significant product development of silica fiber delivery systems has been in side-firing laser delivery systems for Urology. These devices utilize silica-core fibers to project the laser energy at a substantial lateral angle to the conventional delivery system, typically 40 to 100 degrees off axis. Many unique distal tips have been designed to meet the needs of this potentially enormous application. There are three primary technologies employed in side-firing laser delivery systems: reflection off of an attached medium; reflection within an angle-polished fiber through total internal reflection; and reflection from both an angle-polished fiber and an outside medium. Each technology is presented and compared on the basis of operation modality, transmission efficiency, and power-handling performance.

  8. Ultrasonic precision optical grinding technology

    NASA Astrophysics Data System (ADS)

    Cahill, Michael J.; Bechtold, Michael J.; Fess, Edward; Wolfs, Frank L.; Bechtold, Rob

    2015-10-01

    As optical geometries become more precise and complex and a wider range of materials are used, the processes used for manufacturing become more critical. As the preparatory stage for polishing, this is especially true for grinding. Slow processing speeds, accelerated tool wear, and poor surface quality are often detriments in manufacturing glass and hard ceramics. The quality of the ground surface greatly influences the polishing process and the resulting finished product. Through extensive research and development, OptiPro Systems has introduced an ultrasonic assisted grinding technology, OptiSonic, which has numerous advantages over traditional grinding processes. OptiSonic utilizes a custom tool holder designed to produce oscillations in line with the rotating spindle. A newly developed software package called IntelliSonic is integral to this platform. IntelliSonic automatically characterizes the tool and continuously optimizes the output frequency for optimal cutting while in contact with the part. This helps maintain a highly consistent process under changing load conditions for a more accurate surface. Utilizing a wide variety of instruments, test have proven to show a reduction in tool wear and increase in surface quality while allowing processing speeds to be increased. OptiSonic has proven to be an enabling technology to overcome the difficulties seen in grinding of glass and hard optical ceramics. OptiSonic has demonstrated numerous advantages over the standard CNC grinding process. Advantages are evident in reduced tool wear, better surface quality, and reduced cycle times due to increased feed rates. These benefits can be seen over numerous applications within the precision optics industry.

  9. The research and development of the adaptive optics in ophthalmology

    NASA Astrophysics Data System (ADS)

    Wu, Chuhan; Zhang, Xiaofang; Chen, Weilin

    2015-08-01

    Recently the combination of adaptive optics and ophthalmology has made great progress and become highly effective. The retina disease is diagnosed by retina imaging technique based on scanning optical system, so the scanning of eye requires optical system characterized by great ability of anti-moving and optical aberration correction. The adaptive optics possesses high level of adaptability and is available for real time imaging, which meets the requirement of medical retina detection with accurate images. Now the Scanning Laser Ophthalmoscope and the Optical Coherence Tomography are widely used, which are the core techniques in the area of medical retina detection. Based on the above techniques, in China, a few adaptive optics systems used for eye medical scanning have been designed by some researchers from The Institute of Optics And Electronics of CAS(The Chinese Academy of Sciences); some foreign research institutions have adopted other methods to eliminate the interference of eye moving and optical aberration; there are many relevant patents at home and abroad. In this paper, the principles and relevant technique details of the Scanning Laser Ophthalmoscope and the Optical Coherence Tomography are described. And the recent development and progress of adaptive optics in the field of eye retina imaging are analyzed and summarized.

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

    SciTech Connect

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

    2008-02-04

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

  11. Compact MEMS-based adaptive optics: optical coherence tomography for clinical use

    NASA Astrophysics Data System (ADS)

    Chen, Diana C.; Olivier, Scot S.; Jones, Steven M.; Zawadzki, Robert J.; Evans, Julia W.; Choi, Stacey S.; Werner, John S.

    2008-02-01

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

  12. Adaptive Optics Imaging of Exoplanet Host Stars

    NASA Astrophysics Data System (ADS)

    Herman, Miranda; Waaler, Mason; Patience, Jennifer; Ward-Duong, Kimberly; Rajan, Abhijith; McCarthy, Don; Kulesa, Craig; Wilson, Paul A.

    2016-01-01

    With the Arizona Infrared imager and Echelle Spectrograph (ARIES) instrument on the 6.5m MMT telescope, we obtained high angular resolution adaptive optics images of 12 exoplanet host stars. The targets are all systems with exoplanets in extremely close orbits such that the planets transit the host stars and cause regular brightness changes in the stars. The transit depth of the light curve is used to infer the radius and, in combination with radial velocity measurements, the density of the planet, but the results can be biased if the light from the host star is the combined light of a pair of stars in a binary system or a chance alignment of two stars. Given the high frequency of binary star systems and the increasing number of transit exoplanet discoveries from Kepler, K2, and anticipated discoveries with the Transiting Exoplanet Survey Satellite (TESS), this is a crucial point to consider when interpreting exoplanet properties. Companions were identified around five of the twelve targets at separations close enough that the brightness measurements of these host stars are in fact the combined brightness of two stars. Images of the resolved stellar systems and reanalysis of the exoplanet properties accounting for the presence of two stars are presented.

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

    SciTech Connect

    Smith, Mark William; Wick, David Victor

    2004-11-01

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

  14. IC-Compatible Technologies for Optical MEMS

    SciTech Connect

    Krygowski, T.W.; Sniegowski, J.J.

    1999-04-30

    Optical Micro Electro Mechanical Systems (Optical MEMS) Technology holds the promise of one-day producing highly integrated optical systems on a common, monolithic substrate. The choice of fabrication technology used to manufacture Optical MEMS will play a pivotal role in the size, functionality and ultimately the cost of optical Microsystems. By leveraging the technology base developed for silicon integrated circuits, large batches of routers, emitters, detectors and amplifiers will soon be fabricated for literally pennies per part. In this article we review the current status of technologies used for Optical MEMS, as well as fabrication technologies of the future, emphasizing manufacturable surface micromachining approaches to producing reliable, low-cost devices for optical communications applications.

  15. Identification of nonlinear optical systems using adaptive kernel methods

    NASA Astrophysics Data System (ADS)

    Wang, Xiaodong; Zhang, Changjiang; Zhang, Haoran; Feng, Genliang; Xu, Xiuling

    2005-12-01

    An identification approach of nonlinear optical dynamic systems, based on adaptive kernel methods which are modified version of least squares support vector machine (LS-SVM), is presented in order to obtain the reference dynamic model for solving real time applications such as adaptive signal processing of the optical systems. The feasibility of this approach is demonstrated with the computer simulation through identifying a Bragg acoustic-optical bistable system. Unlike artificial neural networks, the adaptive kernel methods possess prominent advantages: over fitting is unlikely to occur by employing structural risk minimization criterion, the global optimal solution can be uniquely obtained owing to that its training is performed through the solution of a set of linear equations. Also, the adaptive kernel methods are still effective for the nonlinear optical systems with a variation of the system parameter. This method is robust with respect to noise, and it constitutes another powerful tool for the identification of nonlinear optical systems.

  16. Simulating Astronomical Adaptive Optics Systems Using Yao

    NASA Astrophysics Data System (ADS)

    Rigaut, François; Van Dam, Marcos

    2013-12-01

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

  17. Modelling global multi-conjugated adaptive optics

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    The recently proposed concept of Global MCAO (GMCAO) aims to look for Natural Guide Stars in a very wide technical Field of View (FoV), to increase the overall sky coverage, and deals with the consequent depth of focus reduction introducing numerically a quite-high number of Virtual Deformable Mirrors (VDMs), which are then the starting point for an optimization of the real DMs shapes for the correction of the -smaller- scientific FoV. To translate the GMCAO concept into a real system, a number of parameters requires to be analyzed and optimized, like the number of references and VDMs to be used, the technical FoV size, the spatial samplings, the sensing wavelength. These and some other major choices, like the open loop WFSs concept and design, will then drive the requirements and the performance of the system (e.g. limiting magnitude, linear response, and sensitivity). This paper collects some major results of the on-going study on the feasibility of an Adaptive Optics system for the E-ELT, based on GMCAO, with a particular emphasis on the sky coverage issue. Besides the sensitivity analysis of the optimization of the already mentioned parameters, such a topic involves the implementation of an IDL code simulation tool to estimate the system performance in terms of Strehl Ratio in a 2×2 arcmin FoV, when a variable number of NGSs and VDMs are used. Different technical FoV diameters for the references selection and various constellations can be also compared. This study could be the starting point for a dedicated laboratory testing and, in the future, an on-sky experiment at an 8m telescope with a "scaled down" demonstrator.

  18. Isoplanatism in a multiconjugate adaptive optics system.

    PubMed

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

    2000-10-01

    Turbulence correction in a large field of view by use of an adaptive optics imaging system with several deformable mirrors (DM's) conjugated to various heights is considered. The residual phase variance is computed for an optimized linear algorithm in which a correction of each turbulent layer is achieved by applying a combination of suitably smoothed and scaled input phase screens to all DM's. Finite turbulence outer scale and finite spatial resolution of the DM's are taken into account. A general expression for the isoplanatic angle thetaM of a system with M mirrors is derived in the limiting case of infinitely large apertures and Kolmogorov turbulence. Like Fried's isoplanatic angle theta0,thetaM is a function only of the turbulence vertical profile, is scalable with wavelength, and is independent of the telescope diameter. Use of angle thetaM permits the gain in the field of view due to the increased number of DM's to be quantified and their optimal conjugate heights to be found. Calculations with real turbulence profiles show that with three DM's a gain of 7-10x is possible, giving the typical and best isoplanatic field-of-view radii of 16 and 30 arcseconds, respectively, at lambda = 0.5 microm. It is shown that in the actual systems the isoplanatic field will be somewhat larger than thetaM owing to the combined effects of finite aperture diameter, finite outer scale, and optimized wave-front spatial filtering. However, this additional gain is not dramatic; it is less than 1.5x for large-aperture telescopes. PMID:11028530

  19. Isoplanatism in a multiconjugate adaptive optics system.

    PubMed

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

    2000-10-01

    Turbulence correction in a large field of view by use of an adaptive optics imaging system with several deformable mirrors (DM's) conjugated to various heights is considered. The residual phase variance is computed for an optimized linear algorithm in which a correction of each turbulent layer is achieved by applying a combination of suitably smoothed and scaled input phase screens to all DM's. Finite turbulence outer scale and finite spatial resolution of the DM's are taken into account. A general expression for the isoplanatic angle thetaM of a system with M mirrors is derived in the limiting case of infinitely large apertures and Kolmogorov turbulence. Like Fried's isoplanatic angle theta0,thetaM is a function only of the turbulence vertical profile, is scalable with wavelength, and is independent of the telescope diameter. Use of angle thetaM permits the gain in the field of view due to the increased number of DM's to be quantified and their optimal conjugate heights to be found. Calculations with real turbulence profiles show that with three DM's a gain of 7-10x is possible, giving the typical and best isoplanatic field-of-view radii of 16 and 30 arcseconds, respectively, at lambda = 0.5 microm. It is shown that in the actual systems the isoplanatic field will be somewhat larger than thetaM owing to the combined effects of finite aperture diameter, finite outer scale, and optimized wave-front spatial filtering. However, this additional gain is not dramatic; it is less than 1.5x for large-aperture telescopes.

  20. Adaptive optics parallel near-confocal scanning ophthalmoscopy.

    PubMed

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

    2016-08-15

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

  1. Adaptive optics parallel near-confocal scanning ophthalmoscopy.

    PubMed

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

    2016-08-15

    We present an adaptive optics parallel near-confocal scanning ophthalmoscope (AOPCSO) using a digital micromirror device (DMD). The imaging light is modulated to be a line of point sources by the DMD, illuminating the retina simultaneously. By using a high-speed line camera to acquire the image and using adaptive optics to compensate the ocular wave aberration, the AOPCSO can image the living human eye with cellular level resolution at the frame rate of 100 Hz. AOPCSO has been demonstrated with improved spatial resolution in imaging of the living human retina compared with adaptive optics line scan ophthalmoscopy. PMID:27519106

  2. Reduction of laser spot elongation in adaptive optics.

    PubMed

    Ribak, Erez N; Ragazzoni, Roberto

    2004-06-15

    Adaptive optics systems measure the wave front to be corrected by use of a reference source, a star, or a laser beacon. Such laser guide stars are a few kilometers long, and when observed near the edges of large telescopes they appear elongated. This limits their utility significantly. However, with more sophisticated launch optics their shape and length can be controlled. We propose to string around the rim of a telescope a number of small telescopes that will add laser beams in the scattering medium to create a compact spot. The method could also be adapted for ocular adaptive optics.

  3. Sensorless adaptive optics implementation in widefield optical sectioning microscopy inside in vivo Drosophila brain

    NASA Astrophysics Data System (ADS)

    Pedrazzani, Mélanie; Loriette, Vincent; Tchenio, Paul; Benrezzak, Sakina; Nutarelli, Daniele; Fragola, Alexandra

    2016-03-01

    We present an implementation of a sensorless adaptive optics loop in a widefield fluorescence microscope. This setup is designed to compensate for aberrations induced by the sample on both excitation and emission pathways. It allows fast optical sectioning inside a living Drosophila brain. We present a detailed characterization of the system performances. We prove that the gain brought to optical sectioning by realizing structured illumination microscopy with adaptive optics down to 50 μm deep inside living Drosophila brain.

  4. Optical technology in medicine and biology: Introduction

    NASA Astrophysics Data System (ADS)

    Burns, Stephen A.; Ediger, Marwood N.; Richards-Kortum, Rebecca R.

    1996-07-01

    This feature issue on Optical Technology in Medicine and Biology is the inaugural feature issue for a new section of Applied Optics devoted to the application of advanced optical techniques to problems in biology, medicine, and biotechnology. Although Applied Optics has always been open to research in these areas, the Optical Society's board of editors decided that the importance of this type of research merited a more prominent and focused presentation. As a result the Optical Technology division of Applied Optics was renamed the Optical Technology and Biomedical Optics division, and four new members were appointed to the Applied Optics editorial board. In addition, a call for papers was issued for an inaugural feature issue. The papers appearing in the current issue are those that were submitted in response to that call for papers and that passed the rite of peer review. The quality and breadth of the papers demonstrate the wisdom of the society's decision. We have important contributions affecting such diverse areas as biologic imaging, drug delivery, tissue optics, and laser surgery. In addition, Applied Optics has seen a sharp increase in the number of regular submissions involving biomedical optics, and the quality and breadth of these papers also bode well for the future of the publication. In addition there is already another joint Applied Optics/Journal of the Optical Society of America A Feature Issue in process, entitled Diffusing Photons in Turbid Media, scheduled for publication in January 1997. We invite you to read the papers and to participate in the future of Biomedical Optics and Optical Biotechnology by submitting manuscripts for review by your peers. We thank the OSA board of editors for this opportunity, and we encourage our colleagues to submit their papers directly to the Optical Society in the future and to share ideas and thoughts on this new area of Applied Optics.

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

    PubMed

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

    2016-09-07

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

  6. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

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

    PubMed

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

    2016-01-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems. PMID:27599635

  8. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

    PubMed Central

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

    2016-01-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems. PMID:27599635

  9. Solar adaptive optics at the Observatorio del Teide, Tenerife

    NASA Astrophysics Data System (ADS)

    Soltau, Dirk; Berkefeld, Thomas; Schmidt, Dirk; von der Lühe, Oskar

    2013-10-01

    Observing the Sun with high angular resolution is difficult because the turbulence in the atmosphere is strongest during day time. In this paper we describe the principles of solar adaptive optics exemplified by the two German solar telescopes VTT and GREGOR at the Observatorio del Teide. With theses systems we obtain near diffraction limited images of the Sun. Ways to overcome the limits of conventional AO by applying multiconjugate adaptive optics (MCAO) are shown.

  10. How adaptive optics may have won the Cold War

    NASA Astrophysics Data System (ADS)

    Tyson, Robert K.

    2013-05-01

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

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

    SciTech Connect

    Bauman, B J; Gavel, D T

    2003-04-23

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

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

    NASA Astrophysics Data System (ADS)

    Bauman, Brian J.; Gavel, Donald T.

    2003-06-01

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

  13. Guide star lasers for adaptive optics

    NASA Astrophysics Data System (ADS)

    Roberts, William Thomas, Jr.

    Exploitation of the imaging capabilities of the new generation of ground-based astronomical telescopes relies heavily on Adaptive Optics (AO). Current AO system designs call for sodium guide star lasers capable of producing at least eight Watts of power tuned to the peak of the sodium D2 line, with a high duty cycle to avoid saturation, and with 0.5-1.0 GHz spectral broadening. This work comprises development and testing of six candidate laser systems and materials which may afford a path to achieving these goals. An end-pumped CW dye laser producing 4.0 Watts of tuned output power was developed and used to obtain the first accurate measurement of sodium layer scattering efficiency. Methods of optimizing the laser output through improving pump overlap efficiency and reducing the number of intracavity scattering surfaces are covered. The 1181 nm fluorescence peak of Mn5+ ion in Ba5 (PO4)3Cl could be tuned and doubled to reach 589 nm. While efforts to grow this crystal were under way, the Mn5+ ion in natural apatite (Ca5(PO4)3F) was studied as a potential laser material. Fluorescence saturation measurements and transmission saturation are presented, as well as efforts to obtain CW lasing in natural apatite. A Q-switched laser color-center laser in LiF : F-2 was developed and successfully tuned and doubled to the sodium D 2 line. Broad-band lasing of 80 mW and tuned narrow-band lasing of 35 mW at 1178 nm were obtained with 275 mW of input pump power at 1064 nm. The measured thermal properties of this material indicate its potential for scaling to much higher power. A Q-switched intracavity Raman laser was developed in which CaWO 4 was used to shift a Nd:YAG laser, the frequency-doubled output of which was centered at 589.3 nm. To obtain light at 589.0 nm, a compositionally tuned pump laser of Nd : Y3Ga1.1Al3.9O 12 was produced which generated the desired shift, but was inhomogeneous broadened, limiting the tunable power of the material. Finally, temperature tuning of

  14. Adaptive optics in digital micromirror based confocal microscopy

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  15. Adaptive sports technology and biomechanics: wheelchairs.

    PubMed

    Cooper, Rory A; De Luigi, Arthur Jason

    2014-08-01

    Wheelchair sports are an important tool in the rehabilitation of people with severe chronic disabilities and have been a driving force for innovation in technology and practice. In this paper, we will present an overview of the adaptive technology used in Paralympic sports with a special focus on wheeled technology and the impact of design on performance (defined as achieving the greatest level of athletic ability and minimizing the risk of injury). Many advances in manual wheelchairs trace their origins to wheelchair sports. Features of wheelchairs that were used for racing and basketball 25 or more years ago have become integral to the manual wheelchairs that people now use every day; moreover, the current components used on ultralight wheelchairs also have benefitted from technological advances developed for sports wheelchairs. For example, the wheels now used on chairs for daily mobility incorporate many of the components first developed for sports chairs. Also, advances in manufacturing and the availability of aerospace materials have driven current wheelchair design and manufacture. Basic principles of sports wheelchair design are universal across sports and include fit; minimizing weight while maintaining high stiffness; minimizing rolling resistance; and optimizing the sports-specific design of the chair. However, a well-designed and fitted wheelchair is not sufficient for optimal sports performance: the athlete must be well trained, skilled, and use effective biomechanics because wheelchair athletes face some unique biomechanical challenges.

  16. Optical technologies for intraoperative neurosurgical guidance.

    PubMed

    Valdés, Pablo A; Roberts, David W; Lu, Fa-Ke; Golby, Alexandra

    2016-03-01

    Biomedical optics is a broadly interdisciplinary field at the interface of optical engineering, biophysics, computer science, medicine, biology, and chemistry, helping us understand light-tissue interactions to create applications with diagnostic and therapeutic value in medicine. Implementation of biomedical optics tools and principles has had a notable scientific and clinical resurgence in recent years in the neurosurgical community. This is in great part due to work in fluorescence-guided surgery of brain tumors leading to reports of significant improvement in maximizing the rates of gross-total resection. Multiple additional optical technologies have been implemented clinically, including diffuse reflectance spectroscopy and imaging, optical coherence tomography, Raman spectroscopy and imaging, and advanced quantitative methods, including quantitative fluorescence and lifetime imaging. Here we present a clinically relevant and technologically informed overview and discussion of some of the major clinical implementations of optical technologies as intraoperative guidance tools in neurosurgery.

  17. An adaptive optic for correcting low-order wavefront aberrations

    SciTech Connect

    Thompson, C A; Wilhelmsen, J

    1999-09-02

    Adaptive Optics used for correcting low-order wavefront aberrations were tested and compared using interferometry, beam propagation, and a far-field test. Results confirm that the design and manufacturing specifications were met. Experimental data also confirms theoretical performance expectations, indicating the usefulness of these optics (especially in a laser-beam processing system), and identifying the resulting differences between the two fabrication methods used to make the optics.

  18. Amplitude variations on the Extreme Adaptive Optics testbed

    SciTech Connect

    Evans, J; Thomas, S; Dillon, D; Gavel, D; Phillion, D; Macintosh, B

    2007-08-14

    High-contrast adaptive optics systems, such as those needed to image extrasolar planets, are known to require excellent wavefront control and diffraction suppression. At the Laboratory for Adaptive Optics on the Extreme Adaptive Optics testbed, we have already demonstrated wavefront control of better than 1 nm rms within controllable spatial frequencies. Corresponding contrast measurements, however, are limited by amplitude variations, including those introduced by the micro-electrical-mechanical-systems (MEMS) deformable mirror. Results from experimental measurements and wave optic simulations of amplitude variations on the ExAO testbed are presented. We find systematic intensity variations of about 2% rms, and intensity variations with the MEMS to be 6%. Some errors are introduced by phase and amplitude mixing because the MEMS is not conjugate to the pupil, but independent measurements of MEMS reflectivity suggest that some error is introduced by small non-uniformities in the reflectivity.

  19. Wavefront sensorless adaptive optics ophthalmoscopy in the human eye.

    PubMed

    Hofer, Heidi; Sredar, Nripun; Queener, Hope; Li, Chaohong; Porter, Jason

    2011-07-18

    Wavefront sensor noise and fidelity place a fundamental limit on achievable image quality in current adaptive optics ophthalmoscopes. Additionally, the wavefront sensor 'beacon' can interfere with visual experiments. We demonstrate real-time (25 Hz), wavefront sensorless adaptive optics imaging in the living human eye with image quality rivaling that of wavefront sensor based control in the same system. A stochastic parallel gradient descent algorithm directly optimized the mean intensity in retinal image frames acquired with a confocal adaptive optics scanning laser ophthalmoscope (AOSLO). When imaging through natural, undilated pupils, both control methods resulted in comparable mean image intensities. However, when imaging through dilated pupils, image intensity was generally higher following wavefront sensor-based control. Despite the typically reduced intensity, image contrast was higher, on average, with sensorless control. Wavefront sensorless control is a viable option for imaging the living human eye and future refinements of this technique may result in even greater optical gains.

  20. Performance of the Gemini Planet Imager’s adaptive optics system

    DOE PAGES

    Poyneer, Lisa A.; Palmer, David W.; Macintosh, Bruce; Savransky, Dmitry; Sadakuni, Naru; Thomas, Sandrine; Véran, Jean-Pierre; Follette, Katherine B.; Greenbaum, Alexandra Z.; Mark Ammons, S.; et al

    2016-01-07

    The Gemini Planet Imager’s adaptive optics (AO) subsystem was designed specifically to facilitate high-contrast imaging. We give a definitive description of the system’s algorithms and technologies as built. Ultimately, the error budget indicates that for all targets and atmospheric conditions AO bandwidth error is the largest term.

  1. A review of optical NDT technologies.

    PubMed

    Zhu, Yong-Kai; Tian, Gui-Yun; Lu, Rong-Sheng; Zhang, Hong

    2011-01-01

    Optical non-destructive testing (NDT) has gained more and more attention in recent years, mainly because of its non-destructive imaging characteristics with high precision and sensitivity. This paper provides a review of the main optical NDT technologies, including fibre optics, electronic speckle, infrared thermography, endoscopic and terahertz technology. Among them, fibre optics features easy integration and embedding, electronic speckle focuses on whole-field high precision detection, infrared thermography has unique advantages for tests of combined materials, endoscopic technology provides images of the internal surface of the object directly, and terahertz technology opens a new direction of internal NDT because of its excellent penetration capability to most of non-metallic materials. Typical engineering applications of these technologies are illustrated, with a brief introduction of the history and discussion of recent progress.

  2. A Review of Optical NDT Technologies

    PubMed Central

    Zhu, Yong-Kai; Tian, Gui-Yun; Lu, Rong-Sheng; Zhang, Hong

    2011-01-01

    Optical non-destructive testing (NDT) has gained more and more attention in recent years, mainly because of its non-destructive imaging characteristics with high precision and sensitivity. This paper provides a review of the main optical NDT technologies, including fibre optics, electronic speckle, infrared thermography, endoscopic and terahertz technology. Among them, fibre optics features easy integration and embedding, electronic speckle focuses on whole-field high precision detection, infrared thermography has unique advantages for tests of combined materials, endoscopic technology provides images of the internal surface of the object directly, and terahertz technology opens a new direction of internal NDT because of its excellent penetration capability to most of non-metallic materials. Typical engineering applications of these technologies are illustrated, with a brief introduction of the history and discussion of recent progress. PMID:22164045

  3. Horizontal Path Laser Communications Employing MEMS Adaptive Optics Correction

    SciTech Connect

    Thompson, C A; Wilks, S C; Brase, J M; Young, R A; Johnson, G W; Ruggiero, A J

    2001-09-05

    Horizontal path laser communications are beginning to provide attractive alternatives for high-speed optical communications, In particular, companies are beginning to sell fiberless alternatives for intranet and sporting event video. These applications are primarily aimed at short distance applications (on the order of 1 km pathlength). There exists a potential need to extend this pathlength to distances much greater than a 1km. For cases of long distance optical propagation, atmospheric turbulence will ultimately limit the maximum achievable data rate. In this paper, we propose a method of improved signal quality through the use of adaptive optics. In particular, we show work in progress toward a high-speed, small footprint Adaptive Optics system for horizontal path laser communications. Such a system relies heavily on recent progress in Micro-Electro-Mechanical Systems (MEMS) deformable mirrors as well as improved communication and computational components. In this paper we detail two Adaptive Optics approaches for improved through-put, the first is the compensated receiver (the traditional Adaptive Optics approach), the second is the compensated transmitter/receiver. The second approach allows for correction of the optical wavefront before transmission from the transmitter and prior to detection at the receiver.

  4. Digital adaptive optics line-scanning confocal imaging system.

    PubMed

    Liu, Changgeng; Kim, Myung K

    2015-01-01

    A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea.

  5. Digital adaptive optics line-scanning confocal imaging system

    PubMed Central

    Liu, Changgeng; Kim, Myung K.

    2015-01-01

    Abstract. A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea. PMID:26140334

  6. Digital adaptive optics line-scanning confocal imaging system.

    PubMed

    Liu, Changgeng; Kim, Myung K

    2015-01-01

    A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea. PMID:26140334

  7. Digital adaptive optics line-scanning confocal imaging system

    NASA Astrophysics Data System (ADS)

    Liu, Changgeng; Kim, Myung K.

    2015-11-01

    A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack-Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea.

  8. Digital optical tape: Technology and standardization issues

    NASA Technical Reports Server (NTRS)

    Podio, Fernando L.

    1996-01-01

    During the coming years, digital data storage technologies will continue an aggressive growth to satisfy the user's need for higher storage capacities, higher data transfer rates and long-term archival media properties. Digital optical tape is a promising technology to satisfy these user's needs. As any emerging data storage technology, the industry faces many technological and standardization challenges. The technological challenges are great, but feasible to overcome. Although it is too early to consider formal industry standards, the optical tape industry has decided to work together by initiating prestandardization efforts that may lead in the future to formal voluntary industry standards. This paper will discuss current industry optical tape drive developments and the types of standards that will be required for the technology. The status of current industry prestandardization efforts will also be discussed.

  9. Adaptive optics wavefront sensors based on photon-counting detector arrays

    NASA Astrophysics Data System (ADS)

    Aull, Brian F.; Schuette, Daniel R.; Reich, Robert K.; Johnson, Robert L.

    2010-07-01

    For adaptive optics systems, there is a growing demand for wavefront sensors that operate at higher frame rates and with more pixels while maintaining low readout noise. Lincoln Laboratory has been investigating Geiger-mode avalanche photodiode arrays integrated with CMOS readout circuits as a potential solution. This type of sensor counts photons digitally within the pixel, enabling data to be read out at high rates without the penalty of readout noise. After a brief overview of adaptive optics sensor development at Lincoln Laboratory, we will present the status of silicon Geigermode- APD technology along with future plans to improve performance.

  10. 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.

  11. The Efficacy of Psychophysiological Measures for Implementing Adaptive Technology

    NASA Technical Reports Server (NTRS)

    Scerbo, Mark W.; Freeman, Frederick G.; Mikulka, Peter J.; Parasuraman, Raja; DiNocero, Francesco; Prinzel, Lawrence J., III

    2001-01-01

    Adaptive automation refers to technology that can change its mode of operation dynamically. Further, both the technology and the operator can initiate changes in the level or mode of automation. The present paper reviews research on adaptive technology. It is divided into three primary sections. In the first section, issues surrounding the development and implementation of adaptive automation are presented. Because physiological-based measures show much promise for implementing adaptive automation, the second section is devoted to examining candidate indices. In the final section, those techniques that show the greatest promise for adaptive automation as well as issues that still need to be resolved are discussed.

  12. New CCD imagers for adaptive optics wavefront sensors

    NASA Astrophysics Data System (ADS)

    Schuette, Daniel R.; Reich, Robert K.; Prigozhin, Ilya; Burke, Barry E.; Johnson, Robert

    2014-08-01

    We report on two recently developed charge-coupled devices (CCDs) for adaptive optics wavefront sensing, both designed to provide exceptional sensitivity (low noise and high quantum efficiency) in high-frame-rate low-latency readout applications. The first imager, the CCID75, is a back-illuminated 16-port 160×160-pixel CCD that has been demonstrated to operate at frame rates above 1,300 fps with noise of < 3 e-. We will describe the architecture of this CCD that enables this level of performance, present and discuss characterization data, and review additional design features that enable unique operating modes for adaptive optics wavefront sensing. We will also present an architectural overview and initial characterization data of a recently designed variation on the CCID75 architecture, the CCID82, which incorporates an electronic shutter to support adaptive optics using Rayleigh beacons.

  13. Wavelet methods in multi-conjugate adaptive optics

    NASA Astrophysics Data System (ADS)

    Helin, T.; Yudytskiy, M.

    2013-08-01

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

  14. Beaconless adaptive-optics technique for HEL beam control

    NASA Astrophysics Data System (ADS)

    Khizhnyak, Anatoliy; Markov, Vladimir

    2016-05-01

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

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

    NASA Technical Reports Server (NTRS)

    Downie, John D.

    1990-01-01

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

  16. Optics technology base R/T program overview

    NASA Technical Reports Server (NTRS)

    Coulter, Daniel R.

    1991-01-01

    NASA is studying a number of advanced optical systems concepts to achieve a variety of science mission goals. Most of these concepts require significant advancements in optics technology. An overview of the Optics Technology base R&T program is presented in outline form. The program structure contains six major program elements: optical materials and coatings, optics modeling, advanced optics fabrication, optical testing, wavefront sensing and control, and sensor optics technology.

  17. Focusing a NIR adaptive optics imager; experience with GSAOI

    NASA Astrophysics Data System (ADS)

    Doolan, Matthew; Bloxham, Gabe; Conroy, Peter; Jones, Damien; McGregor, Peter; Stevanovic, Dejan; Van Harmelen, Jan; Waldron, Liam E.; Waterson, Mark; Zhelem, Ross

    2006-06-01

    The Gemini South Adaptive Optics Imager (GSAOI) to be used with the Multi-Conjugate Adaptive Optics (MCAO) system at Gemini South is currently in the final stages of assembly and testing. GSAOI uses a suite of 26 different filters, made from both BK7 and Fused Silica substrates. These filters, located in a non-collimated beam, work as active optical elements. The optical design was undertaken to ensure that both the filter substrates both focused longitudinally at the same point. During the testing of the instrument it was found that longitudinal focus was filter dependant. The methods used to investigate this are outlined in the paper. These investigations identified several possible causes for the focal shift including substrate material properties in cryogenic conditions and small amounts of residual filter power.

  18. PSF halo reduction in adaptive optics using dynamic pupil masking.

    PubMed

    Osborn, James; Myers, Richard M; Love, Gordon D

    2009-09-28

    We describe a method to reduce residual speckles in an adaptive optics system which add to the halo of the point spread function (PSF). The halo is particularly problematic in astronomical applications involving the detection of faint companions. Areas of the pupil are selected where the residual wavefront aberrations are large and these are masked using a spatial light modulator. The method is also suitable for smaller telescopes without adaptive optics as a relatively simple method to increase the resolution of the telescope. We describe the principle of the technique and show simulation results. PMID:19907514

  19. PSF halo reduction in adaptive optics using dynamic pupil masking.

    PubMed

    Osborn, James; Myers, Richard M; Love, Gordon D

    2009-09-28

    We describe a method to reduce residual speckles in an adaptive optics system which add to the halo of the point spread function (PSF). The halo is particularly problematic in astronomical applications involving the detection of faint companions. Areas of the pupil are selected where the residual wavefront aberrations are large and these are masked using a spatial light modulator. The method is also suitable for smaller telescopes without adaptive optics as a relatively simple method to increase the resolution of the telescope. We describe the principle of the technique and show simulation results.

  20. Robust control of a bimorph mirror for adaptive optics systems.

    PubMed

    Baudouin, Lucie; Prieur, Christophe; Guignard, Fabien; Arzelier, Denis

    2008-07-10

    We apply robust control techniques to an adaptive optics system including a dynamic model of the deformable mirror. The dynamic model of the mirror is a modification of the usual plate equation. We propose also a state-space approach to model the turbulent phase. A continuous time control of our model is suggested, taking into account the frequential behavior of the turbulent phase. An H(infinity) controller is designed in an infinite-dimensional setting. Because of the multivariable nature of the control problem involved in adaptive optics systems, a significant improvement is obtained with respect to traditional single input-single output methods.

  1. Technology of optical azimuth transmission

    NASA Astrophysics Data System (ADS)

    Lu, Honggang; Hu, Chunsheng; Wang, Xingshu; Gao, Yang

    2012-11-01

    It often needs transfer a reference from one place to another place in aerospace and guided missile launching. At first, principles of several typical optical azimuth transmission methods are presented. Several typical methods are introduced, such as Theodolite (including gyro-theodolite) collimation method, Camera series method, Optical apparatus for azimuth method and polarization modulated light transmission method. For these typical azimuth transmission methods, their essential theories are elaborated. Then the devices, the application fields and limitations of these typical methods' are presented. Theodolite (including gyro-theodolite) collimation method is used in the ground assembly of spacecraft. Camera series method and optical apparatus for azimuth method are used in azimuth transmission between different decks of ship. Polarization modulated light transmission method is used in azimuth transmission of rocket and guided missile. At the last, the further developments of these methods are discussed.

  2. Optical Fibre Technology In Poland

    NASA Astrophysics Data System (ADS)

    Szustakowski, MieczysIaw; Romaniuk, Ryszard S.

    1990-02-01

    The academic and industrial community active in the field of optoelectronics in this country is organizing now every two years a major international meeting on Optical Fibres and their Applications. The first meeting was held in 1976 and the fifth in the series during February 1989. The next meeting is scheduled for February 1991. It used to gather 150 contributed and invited papers and a few hundreds of participants both domestic and international. The proceedings of this meeting are now issued by SPIE-The International Society for Optical Engineering (vols. no 670 and 1085).

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

    PubMed

    Downie, J D; Goodman, J W

    1989-10-15

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

  4. 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

  5. Adaptive Optics for the 8 meter Chinese Giant Solar Telescope

    NASA Astrophysics Data System (ADS)

    Beckers, Jacques; Liu, Zhong; Deng, Yuanyong; Ji, Haisheng

    2013-12-01

    Solar ELTs enable diffraction limited imaging of the basic structure of the solar atmosphere. Magneto-hydrodynamic considerations limit their size to about 0.03 arcsec. To observe them in the near-infrared 8-meter class telescopes are needed. The Chinese Giant Solar Telescope, or CGST, is such a NIR solar ELT. It is a Ring Telescope with 8-meter outer diameter and a central clear aperture of about 6-meter diameter. At present various options for such a Gregorian type telescope are under study like a continuous ring made of segments or a multiple aperture ring made of 7 off-axis telescopes. The advantages of such a ring telescope is that its MTF covers all spatial frequencies out to those corresponding to its outer diameter, that its circular symmetry makes it polarization neutral, and that its large central hole helps thermal control and provides ample space for MCAO and Gregorian instrumentation. We present the current status of the design of the CGST. Our thinking is guided by the outstanding performance of the 1-meter vacuum solar telescope of the Yunnan Solar Observatory which like the CGST uses both AO and image reconstruction. Using it with a ring-shape aperture mask the imaging techniques for the CGST are being explored. The CGST will have Multi-Conjugate Adaptive Optics (MCAO). The peculiarities of Atmospheric Wavefront Tomography for Ring Telescopes are aided by the ample availability of guide stars on the Sun. IR MCAO-aided diffraction limited imaging offers the advantage of a large FOV, and high solar magnetic field sensitivity. Site testing is proceeding in western China, (e.g. northern Yunnan Province and Tibet). The CGST is a Chinese solar community project originated by the Yunnan Astronomical Observatory, the National Astronomical Observatories, the Purple Mountain Observatory, the Nanjing University, the Nanjing Institute of Astronomical Optics & Technology and the Beijing Normal University.

  6. Use of electrochromic materials in adaptive optics

    NASA Astrophysics Data System (ADS)

    Kammler, Daniel R.; Yelton, William G.; Sweatt, William C.; Verley, Jason C.

    2005-08-01

    Electrochromic (EC) materials are used in "smart" windows that can be darkened by applying a voltage across an EC stack on the window. The associated change in refractive index (n) in the EC materials might allow their use in tunable or temperature-insensitive Fabry-Perot filters and transmissive-spatial-light-modulators (SLMs). The authors are conducting a preliminary evaluation of these materials in many applications, including target-in-the-loop systems. Data on tungsten oxide, WO3, the workhorse EC material, indicate that it's possible to achieve modest changes in n with only slight increases in absorption between the visible and ~10 μm. This might enable construction of a tunable Fabry-Perot filter consisting of an active EC layer (e.g. WO3) and a proton conductor (e.g.Ta2O5) sandwiched between two gold electrodes. A SLM might be produced by replacing the gold with a transparent conductor (e.g. ITO). This SLM would allow broad-band operation like a micromirror array. Since it's a transmission element, simple optical designs like those in liquid-crystal systems would be possible. Our team has fabricated EC stacks and characterized their switching speed and optical properties (n, k). We plan to study the interplay between process parameters, film properties, and performance characteristics associated with the FP-filter and then extend what we learn to SLMs. Our goals are to understand whether the changes in absorption associated with changes in n are acceptable, and whether it's possible to design an EC-stack that's fast enough to be interesting. We'll present our preliminary findings regarding the potential viability of EC materials for target-in-the-loop applications.

  7. Use of electrochromic materials in adaptive optics.

    SciTech Connect

    Kammler, Daniel R.; Sweatt, William C.; Verley, Jason C.; Yelton, William Graham

    2005-07-01

    Electrochromic (EC) materials are used in 'smart' windows that can be darkened by applying a voltage across an EC stack on the window. The associated change in refractive index (n) in the EC materials might allow their use in tunable or temperature-insensitive Fabry-Perot filters and transmissive-spatial-light-modulators (SLMs). The authors are conducting a preliminary evaluation of these materials in many applications, including target-in-the-loop systems. Data on tungsten oxide, WO{sub 3}, the workhorse EC material, indicate that it's possible to achieve modest changes in n with only slight increases in absorption between the visible and {approx}10 {micro}m. This might enable construction of a tunable Fabry-Perot filter consisting of an active EC layer (e.g. WO{sub 3}) and a proton conductor (e.g.Ta{sub 2}O{sub 5}) sandwiched between two gold electrodes. A SLM might be produced by replacing the gold with a transparent conductor (e.g. ITO). This SLM would allow broad-band operation like a micromirror array. Since it's a transmission element, simple optical designs like those in liquid-crystal systems would be possible. Our team has fabricated EC stacks and characterized their switching speed and optical properties (n, k). We plan to study the interplay between process parameters, film properties, and performance characteristics associated with the FP-filter and then extend what we learn to SLMs. Our goals are to understand whether the changes in absorption associated with changes in n are acceptable, and whether it's possible to design an EC-stack that's fast enough to be interesting. We'll present our preliminary findings regarding the potential viability of EC materials for target-in-the-loop applications.

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

    SciTech Connect

    Simeoni, G. G.; Valicu, R. G.; Borchert, G.; Böni, P.; Rasmussen, N. G.; Yang, F.; Kordel, T.; Holland-Moritz, D.; Kargl, F.; Meyer, A.

    2015-12-14

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

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

    NASA Astrophysics Data System (ADS)

    Simeoni, G. G.; Valicu, R. G.; Borchert, G.; Böni, P.; Rasmussen, N. G.; Yang, F.; Kordel, T.; Holland-Moritz, D.; Kargl, F.; Meyer, A.

    2015-12-01

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

  10. Adapting Books: Ready, Set, Read!: EAT: Equipment, Adaptations, and Technology

    ERIC Educational Resources Information Center

    Schoonover, Judith; Norton-Darr, Sally

    2016-01-01

    Developing multimodal materials to introduce or extend literacy experiences sets the stage for literacy success. Alternative ways to organize, display and arrange, interact and respond to information produces greater understanding of concepts. Adaptations include making books easier to use (turning pages or holding), and text easier to read…

  11. Active reflective components for adaptive optical zoom systems

    NASA Astrophysics Data System (ADS)

    Jungwirth, Matthew Edward Lewis

    This dissertation presents the theoretical and experimental exploration of active reflective components specifically for large-aperture adaptive optical zoom systems. An active reflective component can change its focal length by physically deforming its reflecting surface. Adaptive optical zoom (AOZ) utilizes active components in order to change magnification and achieve optical zoom, as opposed to traditional zooming systems that move elements along the optical axis. AOZ systems are theoretically examined using a novel optical design theory that enables a full-scale tradespace analysis, where optical design begins from a broad perspective and optimizes to a particular system. The theory applies existing strategies for telescope design and aberration simulation to AOZ, culminating in the design of a Cassegrain objective with a 3.3X zoom ratio and a 375mm entrance aperture. AOZ systems are experimentally examined with the development of a large-aperture active mirror constructed of a composite material called carbon fiber reinforced polymer (CFRP). The active CFRP mirror uses a novel actuation method to change radius of curvature, where actuators press against two annular rings placed on the mirror's back. This method enables the radius of curvature to increase from 2000mm to 2010mm. Closed-loop control maintains good optical performance of 1.05 waves peak-to-valley (with respect to a HeNe laser) when the active CFRP mirror is used in conjunction with a commercial deformable mirror.

  12. eXtreme Adaptive Optics Planet Imager: Overview and status

    SciTech Connect

    Macintosh, B A; Bauman, B; Evans, J W; Graham, J; Lockwood, C; Poyneer, L; Dillon, D; Gavel, D; Green, J; Lloyd, J; Makidon, R; Olivier, S; Palmer, D; Perrin, M; Severson, S; Sheinis, A; Sivaramakrishnan, A; Sommargren, G; Soumer, R; Troy, M; Wallace, K; Wishnow, E

    2004-08-18

    As adaptive optics (AO) matures, it becomes possible to envision AO systems oriented towards specific important scientific goals rather than general-purpose systems. One such goal for the next decade is the direct imaging detection of extrasolar planets. An 'extreme' adaptive optics (ExAO) system optimized for extrasolar planet detection will have very high actuator counts and rapid update rates - designed for observations of bright stars - and will require exquisite internal calibration at the nanometer level. In addition to extrasolar planet detection, such a system will be capable of characterizing dust disks around young or mature stars, outflows from evolved stars, and high Strehl ratio imaging even at visible wavelengths. The NSF Center for Adaptive Optics has carried out a detailed conceptual design study for such an instrument, dubbed the eXtreme Adaptive Optics Planet Imager or XAOPI. XAOPI is a 4096-actuator AO system, notionally for the Keck telescope, capable of achieving contrast ratios >10{sup 7} at angular separations of 0.2-1'. ExAO system performance analysis is quite different than conventional AO systems - the spatial and temporal frequency content of wavefront error sources is as critical as their magnitude. We present here an overview of the XAOPI project, and an error budget highlighting the key areas determining achievable contrast. The most challenging requirement is for residual static errors to be less than 2 nm over the controlled range of spatial frequencies. If this can be achieved, direct imaging of extrasolar planets will be feasible within this decade.

  13. Laser guide stars and adaptive optics for astronomy

    SciTech Connect

    Max, C.E.

    1992-07-15

    Five papers are included: feasibility experiment for sodium-alyer laser guide stars at LLNL; system design for a high power sodium beacon laser; sodium guide star adaptive optics system for astronomical imaging in the visible and near-infrared; high frame-rate, large field wavefront sensor; and resolution limits for ground-based astronomical imaging. Figs, tabs, refs.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  15. Optic flow improves adaptability of spatiotemporal characteristics during split-belt locomotor adaptation with tactile stimulation.

    PubMed

    Eikema, Diderik Jan A; Chien, Jung Hung; Stergiou, Nicholas; Myers, Sara A; Scott-Pandorf, Melissa M; Bloomberg, Jacob J; Mukherjee, Mukul

    2016-02-01

    Human locomotor adaptation requires feedback and feed-forward control processes to maintain an appropriate walking pattern. Adaptation may require the use of visual and proprioceptive input to decode altered movement dynamics and generate an appropriate response. After a person transfers from an extreme sensory environment and back, as astronauts do when they return from spaceflight, the prolonged period required for re-adaptation can pose a significant burden. In our previous paper, we showed that plantar tactile vibration during a split-belt adaptation task did not interfere with the treadmill adaptation however, larger overground transfer effects with a slower decay resulted. Such effects, in the absence of visual feedback (of motion) and perturbation of tactile feedback, are believed to be due to a higher proprioceptive gain because, in the absence of relevant external dynamic cues such as optic flow, reliance on body-based cues is enhanced during gait tasks through multisensory integration. In this study, we therefore investigated the effect of optic flow on tactile-stimulated split-belt adaptation as a paradigm to facilitate the sensorimotor adaptation process. Twenty healthy young adults, separated into two matched groups, participated in the study. All participants performed an overground walking trial followed by a split-belt treadmill adaptation protocol. The tactile group (TC) received vibratory plantar tactile stimulation only, whereas the virtual reality and tactile group (VRT) received an additional concurrent visual stimulation: a moving virtual corridor, inducing perceived self-motion. A post-treadmill overground trial was performed to determine adaptation transfer. Interlimb coordination of spatiotemporal and kinetic variables was quantified using symmetry indices and analyzed using repeated-measures ANOVA. Marked changes of step length characteristics were observed in both groups during split-belt adaptation. Stance and swing time symmetries were

  16. Melanoma associated retinopathy: A new dimension using adaptive optics.

    PubMed

    Dabir, Supriya; Mangalesh, Shwetha; Govindraj, Indu; Mallipatna, Ashwin; Battu, Rajani; Shetty, Rohit

    2015-01-01

    We report a 56-year-old male patient, complaining of metamorphopsia in his left eye nevertheless visual acuity, slit lamp, and fundus examinations were within normal limits. Microperimetry (MAIA, Centervue, Italy) revealed central field loss and spectral domain optical coherence tomography (Spectralis, Heidelberg, Germany) showed disrupted cone outer segment tip layer. The patient had a diagnosis of cutaneous melanoma in his foot for which an excision biopsy with lymph node dissection was performed 5 months earlier. Our clinical diagnosis was melanoma-associated retinopathy. Electrophysiology confirmed the diagnosis. Adaptive optics retinal imaging (Imagine eyes, Orsay) was performed to assess the cone mosaic integrity across the central retina. This is the first report on the investigation of autoimmune retinopathy using adaptive optics ophthalmoscopy. This case highlights the viability of innovative diagnostic modalities that aid early detection and subsequent management of vision threatening retinal.

  17. Adaptive Optics Photometry and Astrometry of Binary Stars

    NASA Astrophysics Data System (ADS)

    Roberts, Lewis C., Jr.; Turner, Nils H.; Bradford, L. William; ten Brummelaar, Theo A.; Oppenheimer, Ben R.; Kuhn, Jeff R.; Whitman, Kathryn; Perrin, Marshall D.; Graham, James R.

    2005-11-01

    We present astrometric and photometric measurements of 39 binary stars made with the adaptive optics system on the 3.6 m Advanced Electro-Optical System (AEOS) telescope, taken from 2002 November to 2003 March. The binaries have separations ranging from 0.08" to 5.11" and differential magnitudes ranging from 0.096 to 7.9. Also, we include a list of observations of 23 known binaries that we were unable to resolve. In the process of these measurements, we discovered three new companions to two previously known binary stars. We also discuss the effects of scintillation and anisoplanatism on measurements of binary star photometry in adaptive optics images. Suggestions on how to minimize these effects are then given. Based on observations made at the Maui Space Surveillance System operated by Detachment 15 of the US Air Force Research Laboratory's Directed Energy Directorate.

  18. 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.

  19. 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.

  20. Low-latency adaptive optics system processing electronics

    NASA Astrophysics Data System (ADS)

    Duncan, Terry S.; Voas, Joshua K.; Eager, Robert J.; Newey, Scott C.; Wynia, John L.

    2003-02-01

    Extensive system modeling and analysis clearly shows that system latency is a primary performance driver in closed loop adaptive optical systems. With careful attention to all sensing, processing, and controlling components, system latency can be significantly reduced. Upgrades to the Starfire Optical Range (SOR) 3.5-meter telescope facility adaptive optical system have resulted in a reduction in overall latency from 660 μsec to 297 μsec. Future efforts will reduce the system latency even more to the 170 msec range. The changes improve system bandwidth significantly by reducing the "age" of the correction that is applied to the deformable mirror. Latency reductions have been achieved by increasing the pixel readout pattern and rate on the wavefront sensor, utilizing a new high-speed field programmable gate array (FPGA) based wavefront processor, doubling the processing rate of the real-time reconstructor, and streamlining the operation of the deformable mirror drivers.

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

    NASA Astrophysics Data System (ADS)

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

    2003-03-01

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

  2. SIRTF cryo-optics technology plan

    NASA Technical Reports Server (NTRS)

    Norris, David D.

    1993-01-01

    A study was undertaken, early in 1992, to determine if a SIRTF class mission could be developed to allow the Observatory to be launched on an Atlas IIAS rather than the Titan IV/Centaur previously planned. The substantial mass reduction required to make that change resulted in a new set of requirements for science and a heightened interest in light weight optics. This paper addresses the rationale and plan for the Atlas SIRTF cryo-optics technology plan.

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

    NASA Technical Reports Server (NTRS)

    Downie, John D.; Goodman, Joseph W.

    1989-01-01

    The accuracy requirements of optical processors in adaptive optics systems are determined by estimating the required accuracy in a general optical linear algebra processor (OLAP) that results in a smaller average residual aberration than that achieved with a conventional electronic digital processor with some specific computation speed. Special attention is given to an error analysis of a general OLAP with regard to the residual aberration that is created in an adaptive mirror system by the inaccuracies of the processor, and to the effect of computational speed of an electronic processor on the correction. Results are presented on the ability of an OLAP to compete with a digital processor in various situations.

  4. Optical design trade-offs of the multi conjugate adaptive optics relay for the European Extremely Large Telescope

    NASA Astrophysics Data System (ADS)

    Lombini, Matteo; Diolaiti, Emiliano; De Rosa, Adriano

    2014-08-01

    The scope of this paper is to describe some possible design concepts of the post optical relay inside the multi conjugate adaptive optics module for the European Extremely Large Telescope. The module is planned to be placed at the Nasmyth focus of the telescope. The optical relay must re-image the telescope focal plane with diffraction limited performance and low geometric distortion, for a field of view of 75" and for a wavelength range between 0.8 and 2.4μm. A technical annular field of view with inner diameter of 75" and outer diameter of 160" to search 3 for natural guide stars is also required. Wavefront sensing is performed by means of 6 laser guide stars arranged on a circle of at least 120" diameter while wavefront correction is performed by two deformable mirrors inside the relay, in addition to the telescope adaptive mirror. The final optical design will be a trade-off among adaptive optics performance, optical interface requirements, mechanical interface requirements and technological feasibility of key hardware components. The size of the deformable mirrors and the image quality of the layer conjugates are important design drivers, related to the design of the collimating optics after the input focal plane and to the deformable mirrors tilt respect to the chief ray. The optical interface at the output focal plane must be acceptable for the client instruments, in terms of field curvature, focal ratio and exit pupil position. The number of optical surfaces inside the relay has to be as small as possible to limit thermal background. Splitting of the laser guide star channel from the science light channel may be achieved either in wavelength, by means of a dichroic placed close to a pupil image, or in field, by means of an perforated dichroic placed at an intermediate focal plane. The laser guide star beams have to be focused with acceptable optical performance on a fixed image plane compensating the effects of the sodium layer range variation with Zenith

  5. Optical waveguide tamper sensor technology

    SciTech Connect

    Carson, R.F.; Butler, M.A.; Sinclair, M.B.

    1997-03-01

    Dielectric optical waveguides exhibit properties that are well suited to sensor applications. They have low refractive index and are transparent to a wide range of wavelengths. They can react with the surrounding environment in a variety of controllable ways. In certain sensor applications, it is advantageous to integrate the dielectric waveguide on a semiconductor substrate with active devices. In this work, we demonstrate a tamper sensor based on dielectric waveguides that connect epitaxial GaAs-GaAlAs sources and detectors. The tamper sensing function is realized by attaching particles of absorbing material with high refractive index to the surface of the waveguides. These absorbers are then attached to a lid or cover, as in an integrated circuit package or multi-chip module. The absorbers attenuate the light in the waveguides as a function of absorber interaction. In the tamper indicating mode, the absorbers are placed randomly on the waveguides, to form a unique attenuation pattern that is registered by the relative signal levels on the photodetectors. When the lid is moved, the pattern of absorbers changes, altering the photodetector signals. This dielectric waveguide arrangement is applicable to a variety of sensor functions, and specifically can be fabricated as a chemical sensor by the application of cladding layers that change their refractive index and/or optical absorption properties upon exposure to selected chemical species. An example is found in palladium claddings that are sensitive to hydrogen. A description of designs and a basic demonstration of the tamper sensing and chemical sensing functions is described herein.

  6. Enhanced link availability for free space optical time-frequency transfer using adaptive optic terminals

    NASA Astrophysics Data System (ADS)

    Petrillo, Keith G.; Dennis, Michael L.; Juarez, Juan C.; Souza, Katherine T.; Baumann, Esther; Bergeron, Hugo; Coddington, Ian; Deschenes, Jean-Daniel; Giorgetta, Fabrizio R.; Newbury, Nathan R.; Sinclair, Laura C.; Swann, William C.

    2016-05-01

    Optical time and frequency transfer offers extremely high precision wireless synchronization across multiple platforms for untethered distributed systems. While large apertures provide antenna gain for wireless systems which leads to robust link budgets and operation over increased distance, turbulence disrupts the beam and limits the full realization of the antenna gain. Adaptive optics can correct for phase distortions due to turbulence which potentially increases the total gain of the aperture to that for diffraction-limited operation. Here, we explore the use of adaptive optics terminals for free-space time and frequency transfer. We find that the requirement of reciprocity in a two-way time and frequency transfer link is maintained during the phase compensation of adaptive optics, and that the enhanced link budget due to aperture gain allows for potential system operation over ranges of at least tens of kilometers.

  7. Laser beacon adaptive optics for power beaming applications

    SciTech Connect

    Fugate, R.Q.

    1994-12-31

    This paper discusses the laser beam control system requirements for power beaming applications. Power beaming applications include electric and thermal engine propulsion for orbit transfer, station changing, and recharging batteries. Beam control includes satellite acquisition, high accuracy tracking, higher order atmospheric compensation using adaptive optics, and precision point-ahead. Beam control may also include local laser beam clean-up with a low order adaptive optics system. This paper also presents results of tracking and higher-order correction experiments on astronomical objects. The results were obtained with a laser beacon adaptive optics system at Phillips Laboratory`s Starfire Optical Range near Albuquerque, NM. At a wavelength of 0.85 {mu}m, the author has achieved Strehl ratios of {approximately}0.50 using laser beacons and {approximately}0.65 using natural stars for exposures longer than one minute on objects of {approximately}8{sup th} magnitude. The resulting point spread function has a full width half maximum (FWHM) of 0.13 arcsec.

  8. Smart adaptive optic systems using spatial light modulators.

    PubMed

    Clark, N; Banish, M; Ranganath, H S

    1999-01-01

    Many factors contribute to the aberrations induced in an optical system. Atmospheric turbulence between the object and the imaging system, physical or thermal perturbations in optical elements degrade the system's point spread function, and misaligned optics are the primary sources of aberrations that affect image quality. The design of a nonconventional real-time adaptive optic system using a micro-mirror device for wavefront correction is presented. The unconventional compensated imaging system presented offers advantages in speed, cost, power consumption, and weight. A pulsed-coupled neural network is used to as a preprocessor to enhance the performance of the wavefront sensor for low-light applications. Modeling results that characterize the system performance are presented. PMID:18252558

  9. Fast calibration of high-order adaptive optics systems.

    PubMed

    Kasper, Markus; Fedrigo, Enrico; Looze, Douglas P; Bonnet, Henri; Ivanescu, Liviu; Oberti, Sylvain

    2004-06-01

    We present a new method of calibrating adaptive optics systems that greatly reduces the required calibration time or, equivalently, improves the signal-to-noise ratio. The method uses an optimized actuation scheme with Hadamard patterns and does not scale with the number of actuators for a given noise level in the wavefront sensor channels. It is therefore highly desirable for high-order systems and/or adaptive secondary systems on a telescope without a Gregorian focal plane. In the latter case, the measurement noise is increased by the effects of the turbulent atmosphere when one is calibrating on a natural guide star. PMID:15191182

  10. Fast calibration of high-order adaptive optics systems.

    PubMed

    Kasper, Markus; Fedrigo, Enrico; Looze, Douglas P; Bonnet, Henri; Ivanescu, Liviu; Oberti, Sylvain

    2004-06-01

    We present a new method of calibrating adaptive optics systems that greatly reduces the required calibration time or, equivalently, improves the signal-to-noise ratio. The method uses an optimized actuation scheme with Hadamard patterns and does not scale with the number of actuators for a given noise level in the wavefront sensor channels. It is therefore highly desirable for high-order systems and/or adaptive secondary systems on a telescope without a Gregorian focal plane. In the latter case, the measurement noise is increased by the effects of the turbulent atmosphere when one is calibrating on a natural guide star.

  11. 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.

  12. Efficient manufacturing technology of metal optics

    NASA Astrophysics Data System (ADS)

    Zhang, Jizhen; Wu, Yanxiong; Zhang, Xin; Zhang, Liping; Wang, Lingjie; Qu, Hemeng

    2015-10-01

    The efficient manufacturing technologies greatly accelerate the development and production process. Optical components have higher precision requirements than mechanical parts. This provides great challenge for rapid manufacturing. Metallic optical system is featured high resolution, wide spectral range, light weight, compact design, low cost and short manufacturing period. Reflective mirrors and supporting structures can be made from the same material to improve athermal performance of the system. Common materials for metal mirrors in optical applications include aluminum, copper, beryllium, aluminum beryllium alloy and so on. Their physical characteristics and relative advantages are presented. Most kinds of metals have good machinability and can be manufactured by many kinds of producing methods. This makes metallic optical system saving 30%~60% cost and time than others. The manufacturing process of metal mirror is different due to its working spectral. The metal mirror can be directly manufactured by single point diamond turning. This is an outstanding technique in point of ultra-precision as well as economical manufacture of mirrors. The roughness values and form accuracy of optical surfaces after diamond turning can satisfy the quality level for applications in the near infrared and infrared range. And for visible light spectral the turning structures must be removed with a smoothing procedure in order to minimize the scatter losses. Some smoothing methods to obtain visible quality metal mirrors are given in this paper. Some new manufacturing technology, such as 3D printing, can be used for metallic optical system and several promising techniques are presented.

  13. Adaptive Quality of Transmission Control in Elastic Optical Network

    NASA Astrophysics Data System (ADS)

    Cai, Xinran

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

  14. Configurable adaptive optics for the correction of space-based optical systems

    NASA Astrophysics Data System (ADS)

    McComas, Brian Keith

    Space-based, high resolution, Earth remote sensing systems, that employ large, flexible, lightweight primary mirrors, will require active wavefront correction, in the form of active and adaptive optics, to correct for thermally and vibrationally induced deformations in the optics. These remote sensing systems typically have a large field-of-view. Unlike the adaptive optics on ground-based astronomical telescopes, which have a negligible field-of-view, the adaptive optics on these space-based remote sensing systems will be required to correct the wavefront over the entire field-of-view, which can be several degrees. The error functions for astronomical adaptive optics have been developed for the narrow field-of-view correction of atmospheric turbulence and do not address the needs of wide field space-based systems. To address these needs, a new wide field adaptive optics theory and a new error function are developed. This new error function, which is a new extension of conventional adaptive optics, leads to the development of three new types of imaging systems: wide field-of-view, selectable field-of-view, and steerable field-of-view. These new systems can have nearly diffraction-limited performance across the entire field-of-view or a narrow movable region of high-resolution imaging. The factors limiting system performance are determined and analyzed. The range of applicability of the wide field adaptive optics theory is shown. The range of applicability is used to avoid limitations in system performance and to estimate the optical systems parameters, which will meet the system's performance requirements. Experimental results demonstrate the wide field adaptive optics theory. Finally, it will be shown that a synthetic guide star stimulated from above the atmosphere can be used as a beacon for the wavefront sensors of space-based systems. These wavefront sensors must be optimized such that error in the reconstructed wavefront is minimized. The key equations that

  15. Fiber Optic Communications Technology. A Status Report.

    ERIC Educational Resources Information Center

    Hull, Joseph A.

    Fiber optic communications (communications over very pure glass transmission channels of diameter comparable to a human hair) is an emerging technology which promises most improvements in communications capacity at reasonable cost. The fiber transmission system offers many desirable characteristics representing improvements over conventional…

  16. Applications of Optical Technology: Information Retrieval.

    ERIC Educational Resources Information Center

    O'Connor, Mary Ann

    1991-01-01

    Discusses applications of optical technology, especially CD-ROMs, to information management needs. Information retrieval problems are discussed; design questions that concern the format of the data, indexing methods, and retrieval capabilities are presented; the need for updates is considered; access requirements are discussed; and the importance…

  17. Optical Disc Technology for Information Management.

    ERIC Educational Resources Information Center

    Brumm, Eugenia K.

    1991-01-01

    This summary of the literature on document image processing from 1988-90 focuses on WORM (write once read many) technology and on rewritable (i.e., erasable) optical discs, and excludes CD-ROM. Highlights include vendors and products, standards, comparisons of storage media, software, legal issues, records management, indexing, and computer…

  18. Technology Development for High Efficiency Optical Communications

    NASA Technical Reports Server (NTRS)

    Farr, William H.

    2012-01-01

    Deep space optical communications is a significantly more challenging operational domain than near Earth space optical communications, primarily due to effects resulting from the vastly increased range between transmitter and receiver. The NASA Game Changing Development Program Deep Space Optical Communications Project is developing four key technologies for the implementation of a high efficiency telecommunications system that will enable greater than 10X the data rate of a state-of-the-art deep space RF system (Ka-band) for similar transceiver mass and power burden on the spacecraft. These technologies are a low mass spacecraft disturbance isolation assembly, a flight qualified photon counting detector array, a high efficiency flight laser amplifier and a high efficiency photon counting detector array for the ground-based receiver.

  19. Adaptive optics confocal microscopy using direct wavefront sensing.

    PubMed

    Tao, Xiaodong; Fernandez, Bautista; Azucena, Oscar; Fu, Min; Garcia, Denise; Zuo, Yi; Chen, Diana C; Kubby, Joel

    2011-04-01

    Optical aberrations due to the inhomogeneous refractive index of tissue degrade the resolution and brightness of images in deep-tissue imaging. We introduce a confocal fluorescence microscope with adaptive optics, which can correct aberrations based on direct wavefront measurements using a Shack-Hartmann wavefront sensor with a fluorescent bead used as a point source reference beacon. The results show a 4.3× improvement in the Strehl ratio and a 240% improvement in the signal intensity for fixed mouse tissues at depths of up to 100 μm.

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

    SciTech Connect

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

    2008-09-08

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

  1. Fabricating binary optics: An overview of binary optics process technology

    NASA Technical Reports Server (NTRS)

    Stern, Margaret B.

    1993-01-01

    A review of binary optics processing technology is presented. Pattern replication techniques have been optimized to generate high-quality efficient microoptics in visible and infrared materials. High resolution optical photolithography and precision alignment is used to fabricate maximally efficient fused silica diffractive microlenses at lambda = 633 nm. The degradation in optical efficiency of four-phase-level fused silica microlenses resulting from an intentional 0.35 micron translational error has been systematically measured as a function of lens speed (F/2 - F/60). Novel processes necessary for high sag refractive IR microoptics arrays, including deep anisotropic Si-etching, planarization of deep topography and multilayer resist techniques, are described. Initial results are presented for monolithic integration of photonic and microoptic systems.

  2. Contrast-based sensorless adaptive optics for retinal imaging.

    PubMed

    Zhou, Xiaolin; Bedggood, Phillip; Bui, Bang; Nguyen, Christine T O; He, Zheng; Metha, Andrew

    2015-09-01

    Conventional adaptive optics ophthalmoscopes use wavefront sensing methods to characterize ocular aberrations for real-time correction. However, there are important situations in which the wavefront sensing step is susceptible to difficulties that affect the accuracy of the correction. To circumvent these, wavefront sensorless adaptive optics (or non-wavefront sensing AO; NS-AO) imaging has recently been developed and has been applied to point-scanning based retinal imaging modalities. In this study we show, for the first time, contrast-based NS-AO ophthalmoscopy for full-frame in vivo imaging of human and animal eyes. We suggest a robust image quality metric that could be used for any imaging modality, and test its performance against other metrics using (physical) model eyes.

  3. MEMS-based extreme adaptive optics for planet detection

    SciTech Connect

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

    2005-11-18

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

  4. Neptune and Titan Observed with Keck Telescope Adaptive Optics

    SciTech Connect

    Max, C.E.; Macintosh, B.A.; Gibbard, S.; Gavel, D.T.; Roe, H.; De Pater, I.; Ghez, A.M.; Acton, S.; Wizinowich, P.L.; Lai, O.

    2000-05-05

    The authors report on observations taken during engineering science validation time using the new adaptive optics system at the 10-m Keck II Telescope. They observe Neptune and Titan at near-infrared wavelengths. These objects are ideal for adaptive optics imaging because they are bright and small, yet have many diffraction-limited resolution elements across their disks. In addition Neptune and Titan have prominent physical features, some of which change markedly with time. They have observed infrared-bright storms on Neptune, and very low-albedo surface regions on Titan, Saturn's largest moon, Spatial resolution on Neptune and Titan was 0.05-0.06 and 0.04-0.05 arc sec, respectively.

  5. Contrast-based sensorless adaptive optics for retinal imaging

    PubMed Central

    Zhou, Xiaolin; Bedggood, Phillip; Bui, Bang; Nguyen, Christine T.O.; He, Zheng; Metha, Andrew

    2015-01-01

    Conventional adaptive optics ophthalmoscopes use wavefront sensing methods to characterize ocular aberrations for real-time correction. However, there are important situations in which the wavefront sensing step is susceptible to difficulties that affect the accuracy of the correction. To circumvent these, wavefront sensorless adaptive optics (or non-wavefront sensing AO; NS-AO) imaging has recently been developed and has been applied to point-scanning based retinal imaging modalities. In this study we show, for the first time, contrast-based NS-AO ophthalmoscopy for full-frame in vivo imaging of human and animal eyes. We suggest a robust image quality metric that could be used for any imaging modality, and test its performance against other metrics using (physical) model eyes. PMID:26417525

  6. Art + technology in optics educational outreach programs

    NASA Astrophysics Data System (ADS)

    Silberman, Donn M.

    2007-09-01

    In the modern era, art and technology have been at opposite ends of the spectrum of human study. Artists tend to be non-technical and technologists tend not to be artistic. While this is a broad generalization, it is rare to find an artist teaching science or an engineer teaching art. However, if we think back several centuries, it was very common for great artists to be at the forefront of technology. The prime example being the great Leonardo Di Vinci. Over the past several years, the optics educational outreach programs of the Optics Institute of Southern California (OISC) have incorporated using art and artists to help teach optics and related science. The original use of this was with material from the General Atomics Education Foundation, Color My World, which has been used in a number of settings. Recently, the OISC has partnered with the UC Irvine Beall Center for Art + Technology to provide Family Day Event presentations that use the themes of current Art + Technology exhibits to help attendees learn and understand more about the fundamental science through the art. The two main concepts here are that artists are using science and technology as the basis for their art, also sometimes making some social statements; and the technologists are using the art to make the science more accessible and interesting to the general pubic. This paper weaves a path from the original OISC uses of art to the recent work at UC Irvine.

  7. POPART: partial optical implementation of adaptive resonance theory 2.

    PubMed

    Kane, J S; Paquin, M J

    1993-01-01

    Adaptive resonance architectures are neural nets that are capable of classifying arbitrary input patterns into stable category representations. A hybrid optoelectronic implementation utilizing an optical joint transform correlator is proposed and demonstrated. The resultant optoelectronic system is able to reduce the number of calculations compared to a strictly computer-based approach. The result is that, for larger images, the optoelectronic system is faster than the computer-based approach.

  8. Including outer scale effects in zonal adaptive optics calculations.

    PubMed

    Ellerbroek, B L

    1997-12-20

    Mellin transform techniques are applied to evaluate the covariance of the integrated turbulence-induced phase distortions along a pair of ray paths through the atmosphere from two points in a telescope aperture to a pair of sources at finite or infinite range. The derivation is for the case of a finite outer scale and a von Karman turbulence spectrum. The Taylor hypothesis is assumed if the two phase distortions are evaluated at two different times and amplitude scintillation effects are neglected. The resulting formula for the covariance is a power series in one variable for the case of a fixed atmospheric wind velocity profile and a power series in two variables for a fixed wind-speed profile with a random and uniformly distributed wind direction. These formulas are computationally efficient and can be easily integrated into computer codes for the numerical evaluation of adaptive optics system performance. Sample numerical results are presented to illustrate the effect of a finite outer scale on the performance of natural and laser guide star adaptive optics systems for an 8-m astronomical telescope. A hypothetical outer scale of 10 m significantly reduces the magnitude of tilt anisoplanatism, thereby improving the performance of a laser guide star adaptive optics system if the auxiliary natural star used for full-aperture tip/tilt sensing is offset from the science field. The reduction in higher-order anisoplanatism that is due to a 10-m outer scale is smaller, and the off-axis performance of a natural guide star adaptive optics system is not significantly improved.

  9. LIFT: analysis of performance in a laser assisted adaptive optics

    NASA Astrophysics Data System (ADS)

    Plantet, Cedric; Meimon, Serge; Conan, Jean-Marc; Neichel, Benoît; Fusco, Thierry

    2014-08-01

    Laser assisted adaptive optics systems rely on Laser Guide Star (LGS) Wave-Front Sensors (WFS) for high order aberration measurements, and rely on Natural Guide Stars (NGS) WFS to complement the measurements on low orders such as tip-tilt and focus. The sky-coverage of the whole system is therefore related to the limiting magnitude of the NGS WFS. We have recently proposed LIFT, a novel phase retrieval WFS technique, that allows a 1 magnitude gain over the usually used 2×2 Shack-Hartmann WFS. After an in-lab validation, LIFT's concept has been demonstrated on sky in open loop on GeMS (the Gemini Multiconjugate adaptive optics System at Gemini South). To complete its validation, LIFT now needs to be operated in closed loop in a laser assisted adaptive optics system. The present work gives a detailed analysis of LIFT's behavior in presence of high order residuals and how to limit aliasing effects on the tip/tilt/focus estimation. Also, we study the high orders' impact on noise propagation. For this purpose, we simulate a multiconjugate adaptive optics loop representative of a GeMS-like 5 LGS configuration. The residual high orders are derived from a Fourier based simulation. We demonstrate that LIFT keeps a high performance gain over the Shack-Hartmann 2×2 whatever the turbulence conditions. Finally, we show the first simulation of a closed loop with LIFT estimating turbulent tip/tilt and focus residuals that could be induced by sodium layer's altitude variations.

  10. Mission to Mars: Adaptive Identifier for the Solution of Inverse Optical Metrology Tasks

    NASA Astrophysics Data System (ADS)

    Krapivin, Vladimir F.; Varotsos, Costas A.; Christodoulakis, John

    2016-06-01

    A human mission to Mars requires the solution of many problems that mainly linked to the safety of life, the reliable operational control of drinking water as well as health care. The availability of liquid fuels is also an important issue since the existing tools cannot fully provide the required liquid fuels quantities for the mission return journey. This paper presents the development of new methods and technology for reliable, operational, and with high availability chemical analysis of liquid solutions of various types. This technology is based on the employment of optical sensors (such as the multi-channel spectrophotometers or spectroellipsometers and microwave radiometers) and the development of a database of spectral images for typical liquid solutions that could be the objects of life on Mars. This database exploits the adaptive recognition of optical images of liquids using specific algorithms that are based on spectral analysis, cluster analysis and methods for solving the inverse optical metrology tasks.

  11. Development of silica glass microstructured optical fibers technology in Poland

    NASA Astrophysics Data System (ADS)

    Wójcik, J.; Janoszczyk, B.; Poturaj, K.; Makara, M.; Walewski, A.; Mergo, P.; Klimek, J.; Skorupski, K.; Czyżewska, L.

    2007-04-01

    Paper presents the state of advance of the silica glass microstructured optical fibers technology n Poland especially in Department of Optical Fibers Technology Maria Curie Sklodowska University. Only in this Department there are the technological apparatus for advanced investigations on the technology of the silica glass optical fibers. In paper was describe the technology of optical fiber photonic structure manufacturing, high silica glass synthesis from vapor phase with MCVD and OVD methods. Next was describe some kinds of microstructured optical fibers witch technologies elaborated in UMCS in support of own and received from cooperated research teams optical fibers structures, modeling and measurements results.

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

    PubMed

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

    2012-02-01

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

  13. Basics of videodisc and optical disc technology

    SciTech Connect

    Paris, J.

    1983-11-01

    The optical videodisc is now being used for archival storage of photographs and for records management. The spacedisc project, co-sponsored by nasa and drew university's center for aerospace education, is a prime example of using a videodisc to store individual photographs, slides, and motion sequences with an accompanying paper index. These discs are also used in schools in an interactive individualized learning carrel under microcomputer control. Museums also are using discs as complements to exhibits as well as in cataloging and in classification, information storage and retrieval systems. Ongoing imaginative applications of the optical videodisc include surrogate travel, job performance aids, simulators, electronic malls, and travelogues. Eventually, one will see the videodisc and computer technology with artificial intelligence programs used by the medical community and others. Optical disc and videodisc technology have opened up new horizons for information processing, storage and retrieval, education and training. Regardless of whether a mass consumer market materializes, optical recording technology will play a major role in the future design and development of information systems in the late 1980s and beyond.

  14. Performance assessment of MEMS adaptive optics in tactical airborne systems

    NASA Astrophysics Data System (ADS)

    Tyson, Robert K.

    1999-09-01

    Tactical airborne electro-optical systems are severely constrained by weight, volume, power, and cost. Micro- electrical-mechanical adaptive optics provide a solution that addresses the engineering realities without compromising spatial and temporal compensation requirements. Through modeling and analysis, we determined that substantial benefits could be gained for laser designators, ladar, countermeasures, and missile seekers. The developments potential exists for improving seeker imagery resolution 20 percent, extending countermeasures keep-out range by a factor of 5, doubling the range for ladar detection and identification, and compensating for supersonic and hypersonic aircraft boundary layers. Innovative concepts are required for atmospheric pat hand boundary layer compensation. We have developed design that perform these tasks using high speed scene-based wavefront sensing, IR aerosol laser guide stars, and extended-object wavefront beacons. We have developed a number of adaptive optics system configurations that met the spatial resolution requirements and we have determined that sensing and signal processing requirements can be met. With the help of micromachined deformable mirrors and sensor, we will be able to integrate the systems into existing airborne pods and missiles as well as next generation electro-optical systems.

  15. Lens-based wavefront sensorless adaptive optics swept source OCT

    PubMed Central

    Jian, Yifan; Lee, Sujin; Ju, Myeong Jin; Heisler, Morgan; Ding, Weiguang; Zawadzki, Robert J.; Bonora, Stefano; Sarunic, Marinko V.

    2016-01-01

    Optical coherence tomography (OCT) has revolutionized modern ophthalmology, providing depth resolved images of the retinal layers in a system that is suited to a clinical environment. Although the axial resolution of OCT system, which is a function of the light source bandwidth, is sufficient to resolve retinal features at a micrometer scale, the lateral resolution is dependent on the delivery optics and is limited by ocular aberrations. Through the combination of wavefront sensorless adaptive optics and the use of dual deformable transmissive optical elements, we present a compact lens-based OCT system at an imaging wavelength of 1060 nm for high resolution retinal imaging. We utilized a commercially available variable focal length lens to correct for a wide range of defocus commonly found in patient’s eyes, and a novel multi-actuator adaptive lens for aberration correction to achieve near diffraction limited imaging performance at the retina. With a parallel processing computational platform, high resolution cross-sectional and en face retinal image acquisition and display was performed in real time. In order to demonstrate the system functionality and clinical utility, we present images of the photoreceptor cone mosaic and other retinal layers acquired in vivo from research subjects. PMID:27278853

  16. Optimizing Photon Collection from Point Sources with Adaptive Optics

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  17. Lens-based wavefront sensorless adaptive optics swept source OCT.

    PubMed

    Jian, Yifan; Lee, Sujin; Ju, Myeong Jin; Heisler, Morgan; Ding, Weiguang; Zawadzki, Robert J; Bonora, Stefano; Sarunic, Marinko V

    2016-01-01

    Optical coherence tomography (OCT) has revolutionized modern ophthalmology, providing depth resolved images of the retinal layers in a system that is suited to a clinical environment. Although the axial resolution of OCT system, which is a function of the light source bandwidth, is sufficient to resolve retinal features at a micrometer scale, the lateral resolution is dependent on the delivery optics and is limited by ocular aberrations. Through the combination of wavefront sensorless adaptive optics and the use of dual deformable transmissive optical elements, we present a compact lens-based OCT system at an imaging wavelength of 1060 nm for high resolution retinal imaging. We utilized a commercially available variable focal length lens to correct for a wide range of defocus commonly found in patient's eyes, and a novel multi-actuator adaptive lens for aberration correction to achieve near diffraction limited imaging performance at the retina. With a parallel processing computational platform, high resolution cross-sectional and en face retinal image acquisition and display was performed in real time. In order to demonstrate the system functionality and clinical utility, we present images of the photoreceptor cone mosaic and other retinal layers acquired in vivo from research subjects.

  18. Lens-based wavefront sensorless adaptive optics swept source OCT

    NASA Astrophysics Data System (ADS)

    Jian, Yifan; Lee, Sujin; Ju, Myeong Jin; Heisler, Morgan; Ding, Weiguang; Zawadzki, Robert J.; Bonora, Stefano; Sarunic, Marinko V.

    2016-06-01

    Optical coherence tomography (OCT) has revolutionized modern ophthalmology, providing depth resolved images of the retinal layers in a system that is suited to a clinical environment. Although the axial resolution of OCT system, which is a function of the light source bandwidth, is sufficient to resolve retinal features at a micrometer scale, the lateral resolution is dependent on the delivery optics and is limited by ocular aberrations. Through the combination of wavefront sensorless adaptive optics and the use of dual deformable transmissive optical elements, we present a compact lens-based OCT system at an imaging wavelength of 1060 nm for high resolution retinal imaging. We utilized a commercially available variable focal length lens to correct for a wide range of defocus commonly found in patient’s eyes, and a novel multi-actuator adaptive lens for aberration correction to achieve near diffraction limited imaging performance at the retina. With a parallel processing computational platform, high resolution cross-sectional and en face retinal image acquisition and display was performed in real time. In order to demonstrate the system functionality and clinical utility, we present images of the photoreceptor cone mosaic and other retinal layers acquired in vivo from research subjects.

  19. 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).

  20. Anisoplanatism in adaptive optics systems due to pupil aberrations

    SciTech Connect

    Bauman, B

    2005-08-01

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

  1. Adaptive Hypermedia Educational System Based on XML Technologies.

    ERIC Educational Resources Information Center

    Baek, Yeongtae; Wang, Changjong; Lee, Sehoon

    This paper proposes an adaptive hypermedia educational system using XML technologies, such as XML, XSL, XSLT, and XLink. Adaptive systems are capable of altering the presentation of the content of the hypermedia on the basis of a dynamic understanding of the individual user. The user profile can be collected in a user model, while the knowledge…

  2. Optical technologies for quantum information science

    NASA Astrophysics Data System (ADS)

    Kwiat, Paul G.; Altepeter, Joseph; Barreiro, Julio; Branning, David A.; Jeffrey, Evan R.; Peters, Nicholas; VanDevender, Aaron P.

    2004-02-01

    A number of optical technologies remain to be developed and optimized for various applications in quantum information processing, especially quantum communication. We will give an overview of our approach to some of these, including periodic heralded single-photon sources based on spontaneous parametric down-conversion, ultrabright sources of tunable entangled photons, near unit efficiency single- and multi-photon detectors based on an atomic vapor interaction, quantum state transducers based on high efficiency frequency up-conversion, and low-loss optical quantum memories.

  3. Adaptive Engine Technologies for Aviation CO2 Emissions Reduction

    NASA Technical Reports Server (NTRS)

    Mercer, Carolyn R.; Haller, William J.; Tong, Michael T.

    2006-01-01

    Adaptive turbine engine technologies are assessed for their potential to reduce carbon dioxide emissions from commercial air transports.Technologies including inlet, fan, and compressor flow control, compressor stall control, blade clearance control, combustion control, active bearings and enabling technologies such as active materials and wireless sensors are discussed. The method of systems assessment is described, including strengths and weaknesses of the approach. Performance benefit estimates are presented for each technology, with a summary of potential emissions reduction possible from the development of new, adaptively controlled engine components.

  4. Adaptive and perceptual learning technologies in medical education and training.

    PubMed

    Kellman, Philip J

    2013-10-01

    Recent advances in the learning sciences offer remarkable potential to improve medical education and maximize the benefits of emerging medical technologies. This article describes 2 major innovation areas in the learning sciences that apply to simulation and other aspects of medical learning: Perceptual learning (PL) and adaptive learning technologies. PL technology offers, for the first time, systematic, computer-based methods for teaching pattern recognition, structural intuition, transfer, and fluency. Synergistic with PL are new adaptive learning technologies that optimize learning for each individual, embed objective assessment, and implement mastery criteria. The author describes the Adaptive Response-Time-based Sequencing (ARTS) system, which uses each learner's accuracy and speed in interactive learning to guide spacing, sequencing, and mastery. In recent efforts, these new technologies have been applied in medical learning contexts, including adaptive learning modules for initial medical diagnosis and perceptual/adaptive learning modules (PALMs) in dermatology, histology, and radiology. Results of all these efforts indicate the remarkable potential of perceptual and adaptive learning technologies, individually and in combination, to improve learning in a variety of medical domains.

  5. Lab-on-fiber technology: toward multifunctional optical nanoprobes.

    PubMed

    Consales, Marco; Ricciardi, Armando; Crescitelli, Alessio; Esposito, Emanuela; Cutolo, Antonello; Cusano, Andrea

    2012-04-24

    We propose a reliable fabrication process enabling the integration of dielectric and metallic nanostructures on the tip of optical fibers, thus representing a further step in the "lab-on-fiber" technology roadmap. The proposed fabrication procedure involves conventional deposition and nanopatterning techniques, typically used for planar devices, but here adapted to directly operate on optical fiber tip. Following this approach, we demonstrate a first technological platform based on the integration onto the optical fiber tip of two-dimensional hybrid metallo-dielectric nanostructures supporting localized surface plasmon resonances. By means of experimental measurements and full-wave numerical simulations, we characterize these resonant phenomena and investigate the underlying physics. We show that resonances can be easily tuned by acting on the physical and geometrical parameters of the structure. Moreover, with a view toward possible applications, we present some preliminary results demonstrating how the proposed device can work effectively as an optical probe for label-free chemical and biological sensing as well as a microphone for acoustic wave detection.

  6. 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

  7. Adaptive optics at the Subaru telescope: current capabilities and development

    NASA Astrophysics Data System (ADS)

    Guyon, Olivier; Hayano, Yutaka; Tamura, Motohide; Kudo, Tomoyuki; Oya, Shin; Minowa, Yosuke; Lai, Olivier; Jovanovic, Nemanja; Takato, Naruhisa; Kasdin, Jeremy; Groff, Tyler; Hayashi, Masahiko; Arimoto, Nobuo; Takami, Hideki; Bradley, Colin; Sugai, Hajime; Perrin, Guy; Tuthill, Peter; Mazin, Ben

    2014-08-01

    Current AO observations rely heavily on the AO188 instrument, a 188-elements system that can operate in natural or laser guide star (LGS) mode, and delivers diffraction-limited images in near-IR. In its LGS mode, laser light is transported from the solid state laser to the launch telescope by a single mode fiber. AO188 can feed several instruments: the infrared camera and spectrograph (IRCS), a high contrast imaging instrument (HiCIAO) or an optical integral field spectrograph (Kyoto-3DII). Adaptive optics development in support of exoplanet observations has been and continues to be very active. The Subaru Coronagraphic Extreme-AO (SCExAO) system, which combines extreme-AO correction with advanced coronagraphy, is in the commissioning phase, and will greatly increase Subaru Telescope's ability to image and study exoplanets. SCExAO currently feeds light to HiCIAO, and will soon be combined with the CHARIS integral field spectrograph and the fast frame MKIDs exoplanet camera, which have both been specifically designed for high contrast imaging. SCExAO also feeds two visible-light single pupil interferometers: VAMPIRES and FIRST. In parallel to these direct imaging activities, a near-IR high precision spectrograph (IRD) is under development for observing exoplanets with the radial velocity technique. Wide-field adaptive optics techniques are also being pursued. The RAVEN multi-object adaptive optics instrument was installed on Subaru telescope in early 2014. Subaru Telescope is also planning wide field imaging with ground-layer AO with the ULTIMATE-Subaru project.

  8. Developments in precision optical grinding technology

    NASA Astrophysics Data System (ADS)

    Fess, Edward; Bechtold, Mike; Wolfs, Frank; Bechtold, Rob

    2013-09-01

    Optical systems that utilize complex optical geometries such as aspheres and freeform optics require precise control through the manufacturing process. As the preparatory stage for polishing, this is especially true for grinding. The quality of the grinding process can greatly influence the polishing process and the resultant finished product. OptiPro has performed extensive development work in evaluating components of a precision grinding machine to determine how they influence the overall manufacturing process. For example, spindle technology has a strong effect on how a grinding machine will perform. Through metrology techniques that measure the vibration characteristics of a machine and measurements of grinding forces with a dynamometer, OptiPro has also developed a detailed knowledge of how the machine can influence the grinding process. One of the outcomes of this work has led OptiPro to develop an ultrasonic head for their grinding platform to aid in reducing grinding forces. Initial results show a reduction in force by ~50%.

  9. Optical Technologies for UV Remote Sensing Instruments

    NASA Technical Reports Server (NTRS)

    Keski-Kuha, R. A. M.; Osantowski, J. F.; Leviton, D. B.; Saha, T. T.; Content, D. A.; Boucarut, R. A.; Gum, J. S.; Wright, G. A.; Fleetwood, C. M.; Madison, T. J.

    1993-01-01

    Over the last decade significant advances in technology have made possible development of instruments with substantially improved efficiency in the UV spectral region. In the area of optical coatings and materials, the importance of recent developments in chemical vapor deposited (CVD) silicon carbide (SiC) mirrors, SiC films, and multilayer coatings in the context of ultraviolet instrumentation design are discussed. For example, the development of chemically vapor deposited (CVD) silicon carbide (SiC) mirrors, with high ultraviolet (UV) reflectance and low scatter surfaces, provides the opportunity to extend higher spectral/spatial resolution capability into the 50-nm region. Optical coatings for normal incidence diffraction gratings are particularly important for the evolution of efficient extreme ultraviolet (EUV) spectrographs. SiC films are important for optimizing the spectrograph performance in the 90 nm spectral region. The performance evaluation of the flight optical components for the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument, a spectroscopic instrument to fly aboard the Solar and Heliospheric Observatory (SOHO) mission, designed to study dynamic processes, temperatures, and densities in the plasma of the upper atmosphere of the Sun in the wavelength range from 50 nm to 160 nm, is discussed. The optical components were evaluated for imaging and scatter in the UV. The performance evaluation of SOHO/CDS (Coronal Diagnostic Spectrometer) flight gratings tested for spectral resolution and scatter in the DGEF is reviewed and preliminary results on resolution and scatter testing of Space Telescope Imaging Spectrograph (STIS) technology development diffraction gratings are presented.

  10. LGSD/NGSD: high speed optical CMOS imagers for E-ELT adaptive optics

    NASA Astrophysics Data System (ADS)

    Downing, Mark; Kolb, Johann; Balard, Philippe; Dierickx, Bart; Defernez, Arnaud; Feautrier, Philippe; Finger, Gert; Fryer, Martin; Gach, Jean-Luc; Guillaume, Christian; Hubin, Norbert; Jerram, Paul; Jorden, Paul; Meyer, Manfred; Payne, Andrew; Pike, Andrew; Reyes, Javier; Simpson, Robert; Stadler, Eric; Stent, Jeremy; Swift, Nick

    2014-07-01

    The success of the next generation of instruments for ELT class telescopes will depend upon improving the image quality by exploiting sophisticated Adaptive Optics (AO) systems. One of the critical components of the AO systems for the E-ELT has been identified as the optical Laser/Natural Guide Star WFS detector. The combination of large format, 1760×1680 pixels to finely sample the wavefront and the spot elongation of laser guide stars, fast frame rate of 700 frames per second (fps), low read noise (< 3e-), and high QE (> 90%) makes the development of this device extremely challenging. Design studies concluded that a highly integrated Backside Illuminated CMOS Imager built on High Resistivity silicon as the most likely technology to succeed. Two generations of the CMOS Imager are being developed: a) the already designed and manufactured NGSD (Natural Guide Star Detector), a quarter-sized pioneering device of 880×840 pixels capable of meeting first light needs of the E-ELT; b) the LGSD (Laser Guide Star Detector), the larger full size device. The detailed design is presented including the approach of using massive parallelism (70,400 ADCs) to achieve the low read noise at high pixel rates of ~3 Gpixel/s and the 88 channel LVDS 220Mbps serial interface to get the data off-chip. To enable read noise closer to the goal of 1e- to be achieved, a split wafer run has allowed the NGSD to be manufactured in the more speculative, but much lower read noise, Ultra Low Threshold Transistors in the unit cell. The NGSD has come out of production, it has been thinned to 12μm, backside processed and packaged in a custom 370pin Ceramic PGA (Pin Grid Array). First results of tests performed both at e2v and ESO are presented.

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

    DOEpatents

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

    2010-09-07

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

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

    PubMed

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

    2014-06-30

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

  13. Graphite/Cyanate Ester Face Sheets for Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Bennett, Harold; Shaffer, Joseph; Romeo, Robert

    2008-01-01

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

  14. Hands-on demonstrations and teaching tools for optics and adaptive optics

    NASA Astrophysics Data System (ADS)

    Arion, Douglas N.; Crosby, Kevin M.; Lyons, Daniel; Rand, Kendra; Randolph, Ann

    2003-10-01

    A set of demonstrations suitable for use in classrooms at the secondary, undergraduate and graduate level, and for public use in museums and science centers were developed to exhibit basic optics principles, vision science, and adaptive optics techniques. This paper will exhibit these demonstrations, and how they can be used to promote understanding of optics principles in a wide range of applicable areas. Demonstrations include units showing image formation, orientation, and scale; a unit showing 3-dimensional ray tracing through optical systems using a scattering medium and laser diodes; a unit allowing users to directly observe the color sensitivity of their eyes; and a demonstration directly demonstrating wavefront errors, image distortion, and a Shack-Hartmann sensor for wavefront measurement. Together, these bring real-world optical principles into the hands-on regime, and demystify optics principles that are difficult to visualize in three dimensions. These demonstrations are currently in use at the Keck Observatory in Hawaii, at Nauticus in Virginia, at the Yerkes Observatory and at Carthage College in Wisconsin, as well as at several middle and high schools in Illinois and Wisconsin. They have also been integrated into a unit in the Hands on Universe program published by the Lawrence Hall of Science. This work was supported by the National Science Foundation through the Center for Adaptive Optics.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    In this paper we present the Adaptive Optics Lucky Imager (AOLI), a state-of-the-art instrument which makes use of two well proved techniques for extremely high spatial resolution with ground-based telescopes: Lucky Imaging (LI) and Adaptive Optics (AO). AOLI comprises an AO system, including a low order non-linear curvature wavefront sensor together with a 241 actuators deformable mirror, a science array of four 1024x1024 EMCCDs, allowing a 120×120 down to 36×36" field of view, a calibration subsystem and a powerful LI software. Thanks to the revolutionary WFS, AOLI shall have the capability of using faint reference stars (I˜16.5-17.5), enabling it to be used over a much wider part of the sky than with common Shack-Hartmann AO systems. This instrument saw first light in September 2013 at William Herschel Telescope. Although the instrument was not complete, these commissioning demonstrated its feasibility, obtaining a FWHM for the best PSF of 0.151±0.005" and a plate scale of 55.0±0.3 {mas} {pix}^{-1}. Those observations served us to prove some characteristics of the interesting multiple T Tauri system LkHα 262-263, finding it to be gravitationally bounded. This interesting multiple system mixes the presence of proto-planetary discs, one proved to be double, and the first-time optically resolved pair LkHα 263AB (0.42" separation).

  16. Precision Imaging with Adaptive Optics Aperture Masking Interferometry

    NASA Astrophysics Data System (ADS)

    Martinache, F.; Lloyd, J. P.; Tuthill, P.; Woodruff, H. C.; ten Brummelaar, T.; Turner, N.

    2005-12-01

    Adaptive Optics (AO) enables sensitive diffraction limited imaging from the ground on large telescopes. Much of the promise of AO has yet to be fully realised, due to the difficulties imposed by the complicated, unstable and unknown PSF. At the highest resolutions, (inside the PSF) AO has yet to demonstrate full potential for improvements over speckle techniques. The most precise astronomical speckle imaging observations have resulted from non-redundant pupil masking. We are developing a technique to solve the problem of PSF characterization in AO imaging by synthesizing the heritage of image reconstruction with sparse pupil sampling from astronomical interferometry with the long coherence times available after AO correction. Masking the output pupil of the AO system with a non-redundant array can provide self-calibrated imaging. Further calibration of the MTF can be provided with AO wavefront sensor telemetry data. With a precision calibrated PSF, reliable, well-posed deconvolution is possible. High SNR data and accurate MTF calibration provided by the combination of non-redundant masking and AO system telemetry, allow super-resolution. AEOS provides a unique capability to explore the dynamic range and imaging precision of this technique at visible wavelengths. The NSF/AFOSR program has funded an instrument to explore these new imaging techniques at AEOS. ZOR/AO (Zero Optical Redundance with Adaptive Optics) is presently under construction, to be deployed at AEOS in 2005.

  17. Modeling electrostrictive deformable mirrors in adaptive optics systems

    NASA Astrophysics Data System (ADS)

    Hom, Craig L.; Dean, Peter D.; Winzer, Stephen R.

    2000-06-01

    Adaptive optics correct light wavefront distortion caused by atmospheric turbulence or internal heating of optical components. This distortion often limits performance in ground-based astronomy, space-based earth observation and high energy laser applications. The heart of the adaptive optics system is the deformable mirror. In this study, an electromechanical model of a deformable mirror was developed as a design tool. The model consisted of a continuous, mirrored face sheet driven with multilayered, electrostrictive actuators. A fully coupled constitutive law simulated the nonlinear, electromechanical behavior of the actuators, while finite element computations determined the mirror's mechanical stiffness observed by the array. Static analysis of the mirror/actuator system related different electrical inputs to the array with the deformation of the mirrored surface. The model also examined the nonlinear influence of internal stresses on the active array's electromechanical performance and quantified crosstalk between neighboring elements. The numerical predictions of the static version of the model agreed well with experimental measurements made on an actual mirror system. The model was also used to simulate the systems level performance of a deformable mirror correcting a thermally bloomed laser beam. The nonlinear analysis determined the commanded actuator voltages required for the phase compensation and the resulting wavefront error.

  18. Adapting smartphones for low-cost optical medical imaging

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  19. Interferometric fiber optic gyro (IFOG) technology achievements at Draper Laboratory

    NASA Astrophysics Data System (ADS)

    Laznicka, Oldrich M., Jr.; Freier, Larry J.; Gilmore, Jerold P.; Fontanella, Mark D.

    1994-11-01

    Draper Laboratory's experience with Interferometer Fiber Optic Gyro (IFOG) technology started via an Internal Research and Development effort in 1978. This work led to developing fiber optic gyros in which significant advances in IFOG component technologies, assembly, integration, and test were achieved. In excess of 30 patents have been issued to Draper as a result of this pioneering effort. More recently, Draper collaborated with JPL to transition their fiber optic breadboard gyro to a space qualifiable instrument for interplanetary long duration missions. During the initial phase, brassboard gyros were designed and fabricated that demonstrated performance that bettered NASA's CRAF-Cassini spacecraft objectives. In the second phase, the Engineering Model gyro was developed to meet mission qualification tests. Concurrent with this later phase, analysis, tests and qualification activities were performed to validate that gyro components would realize the required 16 year life. Two major inventions (patent pending) were conceived; one provides for continuous adaptive scale factor stability and the other integrates the optical source and photodetector into a single component [Source Integrated Detector (SID)], thereby eliminating a coupler and several splices thus reducing loss by 6 db. Using the above technologies and the implementation of common mode rejection of laser noise, Draper has defined a low noise high performance gyro in which rate power spectral density (PSD) is projected to be < 7 X 10-7 (deg/hr)2/Hz. In those applications, where the PSD < 4 X 10-5 (deg/hr)2/Hz is sought, a small size three component (SID, integrated optics circuit and fiber coil) gyro is easily implemented.

  20. Correcting the aero-optical aberration of the supersonic mixing layer with adaptive optics: concept validation.

    PubMed

    Gao, Qiong; Jiang, Zongfu; Yi, Shihe; Xie, Wenke; Liao, Tianhe

    2012-06-10

    We describe an adaptive optics (AO) system for correcting the aero-optical aberration of the supersonic mixing layer and test its performance with numerical simulations. The AO system is based on the measurement of distributed Strehl ratios and the stochastic parallel gradient descent (SPGD) algorithm. The aero-optical aberration is computed by the direct numerical simulation of a two-dimensional supersonic mixing layer. When the SPGD algorithm is applied directly, the AO cannot give effective corrections. This paper suggests two strategies to improve the performance of the SPGD algorithm for use in aero-optics. The first one is using an iteration process keeping finite memory, and the second is based on the frozen hypothesis. With these modifications, the performance of AO is improved and the aero-optical aberration can be corrected to some noticeable extent. The possibility of experimental implementation is also discussed. PMID:22695671

  1. Adaptation of Technological Pedagogical Content Knowledge Scale to Turkish

    ERIC Educational Resources Information Center

    Kaya, Zehra; Kaya, Osman Nafiz; Emre, Irfan

    2013-01-01

    The purpose of this study was to adapt "Survey of Pre-service Teachers' Knowledge of Teaching and Technology" in order to assess pre-service primary teachers' Technological Pedagogical Content Knowledge (TPACK) to Turkish. 407 pre-service primary teachers (227 female and 180 male) in their final semester in Education Faculties…

  2. Adaptive Resource Management Technology for Satellite Constellations

    NASA Technical Reports Server (NTRS)

    Welch, Lonnie; Tjaden, Brett; Pfarr, Barbara B.; Hennessy, Joseph F. (Technical Monitor)

    2002-01-01

    This manuscript describes the Sensor Web Adaptive Resource Manager (SWARM) project. The primary focus of the project is on the design and prototyping of middleware for managing computing and network resources in a way that enables the information systems of satellite constellations to provide realtime performance within dynamic environments. The middleware has been prototyped, and it has been evaluated by employing it to manage a pool of distributed resources for the ITOS (Integrated Test and Operations System) satellite command and control software system. The design of the middleware is discussed and a summary of the evaluation effort is provided.

  3. Objective assessment of image quality. IV. Application to adaptive optics

    PubMed Central

    Barrett, Harrison H.; Myers, Kyle J.; Devaney, Nicholas; Dainty, Christopher

    2008-01-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed. PMID:17106464

  4. Objective assessment of image quality. IV. Application to adaptive optics.

    PubMed

    Barrett, Harrison H; Myers, Kyle J; Devaney, Nicholas; Dainty, Christopher

    2006-12-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed.

  5. Objective assessment of image quality. IV. Application to adaptive optics.

    PubMed

    Barrett, Harrison H; Myers, Kyle J; Devaney, Nicholas; Dainty, Christopher

    2006-12-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed. PMID:17106464

  6. Performance of keck adaptive optics with sodium laser guide star

    SciTech Connect

    Gavel, D.T.; Olivier, S.; Brase, J.

    1996-03-08

    The Keck telescope adaptive optics system is designed to optimize performance in he 1 to 3 micron region of observation wavelengths (J, H, and K astronomical bands). The system uses a 249 degree of freedom deformable mirror, so that the interactuator spacing is 56 cm as mapped onto the 10 meter aperture. 56 cm is roughly equal to r0 at 1.4 microns, which implies the wavefront fitting error is 0.52 ({lambda}/2{pi})({ital d}/{ital r}{sub 0}){sup 5/6} = 118 nm rms. This is sufficient to produce a system Strehl of 0.74 at 1.4 microns if all other sources of error are negligible, which would be the case with a bright natural guidestar and very high control bandwidth. Other errors associated with the adaptive optics will however contribute to Strehl degradation, namely, servo bandwidth error due to inability to reject all temporal frequencies of the aberrated wavefront, wavefront measurement error due to finite signal-to-noise ratio in the wavefront sensor, and, in the case of a laser guidestar, the so-called cone effect where rays from the guidestar beacon fail to sample some of the upper atmosphere turbulence. Cone effect is mitigated considerably by the use of the very high altitude sodium laser guidestar (90 km altitude), as opposed to Rayleigh beacons at 20 km. However, considering the Keck telescope`s large aperture, this is still the dominating wavefront error contributor in the current adaptive optics system design.

  7. Application of network control systems for adaptive optics

    NASA Astrophysics Data System (ADS)

    Eager, Robert J.

    2008-04-01

    The communication architecture for most pointing, tracking, and high order adaptive optics control systems has been based on a centralized point-to-point and bus based approach. With the increased use of larger arrays and multiple sensors, actuators and processing nodes, these evolving systems require decentralized control, modularity, flexibility redundancy, integrated diagnostics, dynamic resource allocation, and ease of maintenance to support a wide range of experiments. Network control systems provide all of these critical functionalities. This paper begins with a quick overview of adaptive optics as a control system and communication architecture. It then provides an introduction to network control systems, identifying the key design areas that impact system performance. The paper then discusses the performance test results of a fielded network control system used to implement an adaptive optics system comprised of: a 10KHz, 32x32 spatial selfreferencing interferometer wave front sensor, a 705 channel "Tweeter" deformable mirror, a 177 channel "Woofer" deformable mirror, ten processing nodes, and six data acquisition nodes. The reconstructor algorithm utilized a modulo-2pi wave front phase measurement and a least-squares phase un-wrapper with branch point correction. The servo control algorithm is a hybrid of exponential and infinite impulse response controllers, with tweeter-to-woofer saturation offloading. This system achieved a first-pixel-out to last-mirror-voltage latency of 86 microseconds, with the network accounting for 4 microseconds of the measured latency. Finally, the extensibility of this architecture will be illustrated, by detailing the integration of a tracking sub-system into the existing network.

  8. Night Myopia Studied with an Adaptive Optics Visual Analyzer

    PubMed Central

    Artal, Pablo; Schwarz, Christina; Cánovas, Carmen; Mira-Agudelo, Alejandro

    2012-01-01

    Purpose Eyes with distant objects in focus in daylight are thought to become myopic in dim light. This phenomenon, often called “night myopia” has been studied extensively for several decades. However, despite its general acceptance, its magnitude and causes are still controversial. A series of experiments were performed to understand night myopia in greater detail. Methods We used an adaptive optics instrument operating in invisible infrared light to elucidate the actual magnitude of night myopia and its main causes. The experimental setup allowed the manipulation of the eye's aberrations (and particularly spherical aberration) as well as the use of monochromatic and polychromatic stimuli. Eight subjects with normal vision monocularly determined their best focus position subjectively for a Maltese cross stimulus at different levels of luminance, from the baseline condition of 20 cd/m2 to the lowest luminance of 22×10−6 cd/m2. While subjects performed the focusing tasks, their eye's defocus and aberrations were continuously measured with the 1050-nm Hartmann-Shack sensor incorporated in the adaptive optics instrument. The experiment was repeated for a variety of controlled conditions incorporating specific aberrations of the eye and chromatic content of the stimuli. Results We found large inter-subject variability and an average of −0.8 D myopic shift for low light conditions. The main cause responsible for night myopia was the accommodation shift occurring at low light levels. Other factors, traditionally suggested to explain night myopia, such as chromatic and spherical aberrations, have a much smaller effect in this mechanism. Conclusions An adaptive optics visual analyzer was applied to study the phenomenon of night myopia. We found that the defocus shift occurring in dim light is mainly due to accommodation errors. PMID:22768343

  9. Monte-Carlo modelling of multi-object adaptive optics performance on the European Extremely Large Telescope

    NASA Astrophysics Data System (ADS)

    Basden, A. G.; Morris, T. J.

    2016-09-01

    The performance of a wide-field adaptive optics system depends on input design parameters. Here we investigate the performance of a multi-object adaptive optics system design for the European Extremely Large Telescope, using an end-to-end Monte-Carlo adaptive optics simulation tool, DASP, with relevance for proposed instruments such as MOSAIC. We consider parameters such as the number of laser guide stars, sodium layer depth, wavefront sensor pixel scale, actuator pitch and natural guide star availability. We provide potential areas where costs savings can be made, and investigate trade-offs between performance and cost, and provide solutions that would enable such an instrument to be built with currently available technology. Our key recommendations include a trade-off for laser guide star wavefront sensor pixel scale of about 0.7 arcseconds per pixel, and a field of view of at least 7 arcseconds, that EMCCD technology should be used for natural guide star wavefront sensors even if reduced frame rate is necessary, and that sky coverage can be improved by a slight reduction in natural guide star sub-aperture count without significantly affecting tomographic performance. We find that adaptive optics correction can be maintained across a wide field of view, up to 7 arcminutes in diameter. We also recommend the use of at least 4 laser guide stars, and include ground-layer and multi-object adaptive optics performance estimates.

  10. Light sheet adaptive optics microscope for 3D live imaging

    NASA Astrophysics Data System (ADS)

    Bourgenot, C.; Taylor, J. M.; Saunter, C. D.; Girkin, J. M.; Love, G. D.

    2013-02-01

    We report on the incorporation of adaptive optics (AO) into the imaging arm of a selective plane illumination microscope (SPIM). SPIM has recently emerged as an important tool for life science research due to its ability to deliver high-speed, optically sectioned, time-lapse microscope images from deep within in vivo selected samples. SPIM provides a very interesting system for the incorporation of AO as the illumination and imaging paths are decoupled and AO may be useful in both paths. In this paper, we will report the use of AO applied to the imaging path of a SPIM, demonstrating significant improvement in image quality of a live GFP-labeled transgenic zebrafish embryo heart using a modal, wavefront sensorless approach and a heart synchronization method. These experimental results are linked to a computational model showing that significant aberrations are produced by the tube holding the sample in addition to the aberration from the biological sample itself.

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

    PubMed

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

    2015-08-01

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

  12. Imaging of retinal vasculature using adaptive optics SLO/OCT.

    PubMed

    Felberer, Franz; Rechenmacher, Matthias; Haindl, Richard; Baumann, Bernhard; Hitzenberger, Christoph K; Pircher, Michael

    2015-04-01

    We use our previously developed adaptive optics (AO) scanning laser ophthalmoscope (SLO)/ optical coherence tomography (OCT) instrument to investigate its capability for imaging retinal vasculature. The system records SLO and OCT images simultaneously with a pixel to pixel correspondence which allows a direct comparison between those imaging modalities. Different field of views ranging from 0.8°x0.8° up to 4°x4° are supported by the instrument. In addition a dynamic focus scheme was developed for the AO-SLO/OCT system in order to maintain the high transverse resolution throughout imaging depth. The active axial eye tracking that is implemented in the OCT channel allows time resolved measurements of the retinal vasculature in the en-face imaging plane. Vessel walls and structures that we believe correspond to individual erythrocytes could be visualized with the system.

  13. Widefield multiphoton microscopy with image-based adaptive optics

    NASA Astrophysics Data System (ADS)

    Chang, C.-Y.; Cheng, L.-C.; Su, H.-W.; Yen, W.-C.; Chen, S.-J.

    2012-10-01

    Unlike conventional multiphoton microscopy according to pixel by pixel point scanning, a widefield multiphoton microscope based on spatiotemporal focusing has been developed to provide fast optical sectioning images at a frame rate over 100 Hz. In order to overcome the aberrations of the widefield multiphoton microscope and the wavefront distortion from turbid biospecimens, an image-based adaptive optics system (AOS) was integrated. The feedback control signal of the AOS was acquired according to locally maximize image intensity, which were provided by the widefield multiphoton excited microscope, by using a hill climbing algorithm. Then, the control signal was utilized to drive a deformable mirror in such a way as to eliminate the aberration and distortion. A R6G-doped PMMA thin film is also increased by 3.7-fold. Furthermore, the TPEF image quality of 1 μm fluorescent beads sealed in agarose gel at different depths is improved.

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

    PubMed

    Antonello, Jacopo; van Werkhoven, Tim; Verhaegen, Michel; Truong, Hoa H; Keller, Christoph U; Gerritsen, Hans C

    2014-06-01

    Optical aberrations have detrimental effects in multiphoton microscopy. These effects can be curtailed by implementing model-based wavefront sensorless adaptive optics, which only requires the addition of a wavefront shaping device, such as a deformable mirror (DM) to an existing microscope. The aberration correction is achieved by maximizing a suitable image quality metric. We implement a model-based aberration correction algorithm in a second-harmonic microscope. The tip, tilt, and defocus aberrations are removed from the basis functions used for the control of the DM, as these aberrations induce distortions in the acquired images. We compute the parameters of a quadratic polynomial that is used to model the image quality metric directly from experimental input-output measurements. Finally, we apply the aberration correction by maximizing the image quality metric using the least-squares estimate of the unknown aberration.

  15. Limitations to adaptive optics image quality in rodent eyes.

    PubMed

    Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

    2012-08-01

    Adaptive optics (AO) retinal image quality of rodent eyes is inferior to that of human eyes, despite the promise of greater numerical aperture. This paradox challenges several assumptions commonly made in AO imaging, assumptions which may be invalidated by the very high power and dioptric thickness of the rodent retina. We used optical modeling to compare the performance of rat and human eyes under conditions that tested the validity of these assumptions. Results showed that AO image quality in the human eye is robust to positioning errors of the AO corrector and to differences in imaging depth and wavelength compared to the wavefront beacon. In contrast, image quality in the rat eye declines sharply with each of these manipulations, especially when imaging off-axis. However, some latitude does exist to offset these manipulations against each other to produce good image quality.

  16. Fourier transform digital holographic adaptive optics imaging system

    PubMed Central

    Liu, Changgeng; Yu, Xiao; Kim, Myung K.

    2013-01-01

    A Fourier transform digital holographic adaptive optics imaging system and its basic principles are proposed. The CCD is put at the exact Fourier transform plane of the pupil of the eye lens. The spherical curvature introduced by the optics except the eye lens itself is eliminated. The CCD is also at image plane of the target. The point-spread function of the system is directly recorded, making it easier to determine the correct guide-star hologram. Also, the light signal will be stronger at the CCD, especially for phase-aberration sensing. Numerical propagation is avoided. The sensor aperture has nothing to do with the resolution and the possibility of using low coherence or incoherent illumination is opened. The system becomes more efficient and flexible. Although it is intended for ophthalmic use, it also shows potential application in microscopy. The robustness and feasibility of this compact system are demonstrated by simulations and experiments using scattering objects. PMID:23262541

  17. Six-channel adaptive fibre-optic interferometer

    SciTech Connect

    Romashko, R V; Bezruk, M N; Kamshilin, A A; Kulchin, Yurii N

    2012-06-30

    We have proposed and analysed a scheme for the multiplexing of orthogonal dynamic holograms in photorefractive crystals which ensures almost zero cross talk between the holographic channels upon phase demodulation. A six-channel adaptive fibre-optic interferometer was built, and the detection limit for small phase fluctuations in the channels of the interferometer was determined to be 2.1 Multiplication-Sign 10{sup -8} rad W{sup 1/2} Hz{sup -1/2}. The channel multiplexing capacity of the interferometer was estimated. The formation of 70 channels such that their optical fields completely overlap in the crystal reduces the relative detection limit in the working channel by just 10 %. We found conditions under which the maximum cross talk between the channels was within the intrinsic noise level in the channels (-47 dB).

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

    NASA Astrophysics Data System (ADS)

    Ryder, Stuart D.; Mattila, Seppo; Kankare, Erkki; Väisänen, Petri

    2014-07-01

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

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

    PubMed

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

    2008-01-10

    We present methods used to determine the linear or nonlinear static response and the linear dynamic response of an adaptive optics (AO) system. This AO system consists of a nonlinear microelectromechanical systems deformable mirror (DM), a linear tip-tilt mirror (TTM), a control computer, and a Shack-Hartmann wavefront sensor. The system is modeled using a single-input-single-output structure to determine the one-dimensional transfer function of the dynamic response of the chain of system hardware. An AO system has been shown to be able to characterize its own response without additional instrumentation. Experimentally determined models are given for a TTM and a DM. PMID:18188192

  20. Performance predictions for the Keck telescope adaptive optics system

    SciTech Connect

    Gavel, D.T.; Olivier, S.S.

    1995-08-07

    The second Keck ten meter telescope (Keck-11) is slated to have an infrared-optimized adaptive optics system in the 1997--1998 time frame. This system will provide diffraction-limited images in the 1--3 micron region and the ability to use a diffraction-limited spectroscopy slit. The AO system is currently in the preliminary design phase and considerable analysis has been performed in order to predict its performance under various seeing conditions. In particular we have investigated the point-spread function, energy through a spectroscopy slit, crowded field contrast, object limiting magnitude, field of view, and sky coverage with natural and laser guide stars.

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

    PubMed

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

    2015-06-01

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

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

    PubMed

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

    2015-06-01

    Here we demonstrate a new imaging system that addresses several major problems limiting the clinical utility of conventional adaptive optics scanning light ophthalmoscopy (AOSLO), including its small field of view (FOV), reliance on patient fixation for targeting imaging, and substantial post-processing time. We previously showed an efficient image based eye tracking method for real-time optical stabilization and image registration in AOSLO. However, in patients with poor fixation, eye motion causes the FOV to drift substantially, causing this approach to fail. We solve that problem here by tracking eye motion at multiple spatial scales simultaneously by optically and electronically integrating a wide FOV SLO (WFSLO) with an AOSLO. This multi-scale approach, implemented with fast tip/tilt mirrors, has a large stabilization range of ± 5.6°. Our method consists of three stages implemented in parallel: 1) coarse optical stabilization driven by a WFSLO image, 2) fine optical stabilization driven by an AOSLO image, and 3) sub-pixel digital registration of the AOSLO image. We evaluated system performance in normal eyes and diseased eyes with poor fixation. Residual image motion with incremental compensation after each stage was: 1) ~2-3 arc minutes, (arcmin) 2) ~0.5-0.8 arcmin and, 3) ~0.05-0.07 arcmin, for normal eyes. Performance in eyes with poor fixation was: 1) ~3-5 arcmin, 2) ~0.7-1.1 arcmin and 3) ~0.07-0.14 arcmin. We demonstrate that this system is capable of reducing image motion by a factor of ~400, on average. This new optical design provides additional benefits for clinical imaging, including a steering subsystem for AOSLO that can be guided by the WFSLO to target specific regions of interest such as retinal pathology and real-time averaging of registered images to eliminate image post-processing. PMID:26114033

  3. 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.

  4. Phase aberration correction by correlation in digital holographic adaptive optics

    PubMed Central

    Liu, Changgeng; Yu, Xiao; Kim, Myung K.

    2013-01-01

    We present a phase aberration correction method based on the correlation between the complex full-field and guide-star holograms in the context of digital holographic adaptive optics (DHAO). Removal of a global quadratic phase term before the correlation operation plays an important role in the correction. Correlation operation can remove the phase aberration at the entrance pupil plane and automatically refocus the corrected optical field. Except for the assumption that most aberrations lie at or close to the entrance pupil, the presented method does not impose any other constraints on the optical systems. Thus, it greatly enhances the flexibility of the optical design for DHAO systems in vision science and microscopy. Theoretical studies show that the previously proposed Fourier transform DHAO (FTDHAO) is just a special case of this general correction method, where the global quadratic phase term and a defocus term disappear. Hence, this correction method realizes the generalization of FTDHAO into arbitrary DHAO systems. The effectiveness and robustness of this method are demonstrated by simulations and experiments. PMID:23669707

  5. Adaptive optics for high data rate satellite to ground laser link

    NASA Astrophysics Data System (ADS)

    Védrenne, N.; Conan, J.-M.; Petit, C.; Michau, V.

    2016-03-01

    To match the increasing need for high data rate between high altitude platforms and ground free space optics links are investigated. Part of the growing interest is motivated by the possibility to reap the benefits of the technological maturity of the fibered components. This requires the injection of the received wave into a single mode fiber. To reduce injection losses on the ground terminal the use of adaptive optics (AO) is investigated. The AO system must work for a wide variety of turbulence conditions: by daytime and nighttime, at potentially very low elevations for LEO satellites, with localizations of optical ground stations that could be unfavorable regarding atmospheric turbulence. Contrary to astronomy where the quantity optimized is the average Strehl ratio, for free space communications statistical and temporal characteristics of the injection losses must be taken into account. The consequences of a partial correction are investigated here by numerical simulation for both GEO and LEO to ground links.

  6. Optical coherence tomography: technology and applications

    NASA Astrophysics Data System (ADS)

    Chang, Shoude; Mao, Youxin; Flueraru, Costel; Sherif, Sherif

    2008-12-01

    Optical coherence tomography (OCT) has recently emerged as a powerful optical imaging instrument and technology. OCT performs high resolution, cross-sectional tomographic imaging of the internal structure in 3D materials including biological tissues. Advantages of OCT vs. other imaging systems are: 1) High resolution: enables greater visualization of defects. (OCT: 5-10 microns, ultrasound: 150 microns. High resolution CT: 300 microns. MRI: 1,000 microns). 2) Noninvasive, non-contact: increase ease of use. 3) Fiber-optics delivery: allows OCT to be used in catheters and endoscopes. (Fiber diameter is normally 125 microns). 4) High speed: enables high-resolution 3D imaging. 5) Potential for additional information: polarization contrast and spectroscopic information can be obtained concurrently yielding new information of the testing tissues. 6) Use of non-harmful radiation. In this paper, we shortly review the technologies of OCT and present our works in design and implementation of fiber based OCT systems and full-field OCT systems, including high performance swept source, fibre probe, hardware, software design as well as system configurations. The applications of OCT involving in medical imaging, industrial inspection, information storage and retrieval, as well as biometrics and document security are also briefly introduced and demonstrated.

  7. Photonics technology development for optical fuzing

    NASA Astrophysics Data System (ADS)

    Geib, K. M.; Serkland, D. K.; Keeler, G. A.; Peake, G. M.; Mar, A.; von der Lippe, C. M.; Liu, J. J.

    2005-09-01

    This paper describes the photonic component development taking place at Sandia National Laboratories, ARDEC and the Army Research Laboratory in support of an effort to develop a robust, compact, and affordable photonic proximity sensor for munitions fuzing applications. Successful implementation of this sensor will provide a new capability for direct fire applications. The technologies under investigation for the optical fuze design covered in this paper are vertical-cavity surface-emitting lasers (VCSELs), vertical-external-cavity surface-emitting lasers (VECSELs), integrated resonant-cavity photodetectors (RCPDs), and refractive micro-optics. The culmination of this work will be low cost, robust, fully integrated, g-hardened components suitable for proximity fuzing applications. The use of advanced photonic components will enable replacement of costly assemblies that employ discrete lasers, photodetectors, and bulk optics. The integrated devices will be mass produced and impart huge savings for a variety of Army applications. The specific application under investigation is for gun-fired munitions. Nevertheless, numerous civilian uses exist for this proximity sensor in automotive, robotics and aerospace applications. This technology is also applicable to robotic ladar and short-range 3-D imaging.

  8. Optical coating technology for the EUV

    NASA Technical Reports Server (NTRS)

    Osantowski, J. F.; Keski-Kuha, R. A. M.; Herzig, H.; Toft, A. R.; Gum, J. S.; Fleetwood, C. M.

    1991-01-01

    Advances in optical coating and materials technology are one of the key motivators for the development of missions such as the Far Ultraviolet Spectroscopic Explorer recently selected by NASA for an Explorer class mission in the mid 1990's. The performance of a range of candidate coatings are reviewed for normal-incidence and glancing-incidence applications, and attention is given to strengths and problem areas for their use in space. The importance of recent developments in multilayer films, chemical-vapor deposited SiC (CVD-SiC) mirrors, and SiC films are discussed in the context of EUV instrumentation design. For example, the choice of optical coatings is a design driver for the selection of the average glancing angle for the FUSE telescope, and impacts efficiency, short-wavelength cut-off, and physical size.

  9. In vivo imaging of human photoreceptor mosaic with wavefront sensorless adaptive optics optical coherence tomography.

    PubMed

    Wong, Kevin S K; Jian, Yifan; Cua, Michelle; Bonora, Stefano; Zawadzki, Robert J; Sarunic, Marinko V

    2015-02-01

    Wavefront sensorless adaptive optics optical coherence tomography (WSAO-OCT) is a novel imaging technique for in vivo high-resolution depth-resolved imaging that mitigates some of the challenges encountered with the use of sensor-based adaptive optics designs. This technique replaces the Hartmann Shack wavefront sensor used to measure aberrations with a depth-resolved image-driven optimization algorithm, with the metric based on the OCT volumes acquired in real-time. The custom-built ultrahigh-speed GPU processing platform and fast modal optimization algorithm presented in this paper was essential in enabling real-time, in vivo imaging of human retinas with wavefront sensorless AO correction. WSAO-OCT is especially advantageous for developing a clinical high-resolution retinal imaging system as it enables the use of a compact, low-cost and robust lens-based adaptive optics design. In this report, we describe our WSAO-OCT system for imaging the human photoreceptor mosaic in vivo. We validated our system performance by imaging the retina at several eccentricities, and demonstrated the improvement in photoreceptor visibility with WSAO compensation.

  10. In vivo imaging of human photoreceptor mosaic with wavefront sensorless adaptive optics optical coherence tomography

    PubMed Central

    Wong, Kevin S. K.; Jian, Yifan; Cua, Michelle; Bonora, Stefano; Zawadzki, Robert J.; Sarunic, Marinko V.

    2015-01-01

    Wavefront sensorless adaptive optics optical coherence tomography (WSAO-OCT) is a novel imaging technique for in vivo high-resolution depth-resolved imaging that mitigates some of the challenges encountered with the use of sensor-based adaptive optics designs. This technique replaces the Hartmann Shack wavefront sensor used to measure aberrations with a depth-resolved image-driven optimization algorithm, with the metric based on the OCT volumes acquired in real-time. The custom-built ultrahigh-speed GPU processing platform and fast modal optimization algorithm presented in this paper was essential in enabling real-time, in vivo imaging of human retinas with wavefront sensorless AO correction. WSAO-OCT is especially advantageous for developing a clinical high-resolution retinal imaging system as it enables the use of a compact, low-cost and robust lens-based adaptive optics design. In this report, we describe our WSAO-OCT system for imaging the human photoreceptor mosaic in vivo. We validated our system performance by imaging the retina at several eccentricities, and demonstrated the improvement in photoreceptor visibility with WSAO compensation. PMID:25780747

  11. Non-iterative adaptive optical microscopy using wavefront sensing

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1998-07-01

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

  13. Adaptive Optics Imaging Survey of Luminous Infrared Galaxies

    SciTech Connect

    Laag, E A; Canalizo, G; van Breugel, W; Gates, E L; de Vries, W; Stanford, S A

    2006-03-13

    We present high resolution imaging observations of a sample of previously unidentified far-infrared galaxies at z < 0.3. The objects were selected by cross-correlating the IRAS Faint Source Catalog with the VLA FIRST catalog and the HST Guide Star Catalog to allow for adaptive optics observations. We found two new ULIGs (with L{sub FIR} {ge} 10{sup 12} L{sub {circle_dot}}) and 19 new LIGs (with L{sub FIR} {ge} 10{sup 11} L{sub {circle_dot}}). Twenty of the galaxies in the sample were imaged with either the Lick or Keck adaptive optics systems in H or K{prime}. Galaxy morphologies were determined using the two dimensional fitting program GALFIT and the residuals examined to look for interesting structure. The morphologies reveal that at least 30% are involved in tidal interactions, with 20% being clear mergers. An additional 50% show signs of possible interaction. Line ratios were used to determine powering mechanism; of the 17 objects in the sample showing clear emission lines--four are active galactic nuclei and seven are starburst galaxies. The rest exhibit a combination of both phenomena.

  14. A brief examination of optical tagging technologies.

    SciTech Connect

    Ackermann, Mark R.; Cahill, Paul A. (Aspecular Optics, Dayton, OH); Drummond, Timothy J.; Wilcoxon, Jess Patrick

    2003-07-01

    Presented within this report are the results of a brief examination of optical tagging technologies funded by the Laboratory Directed Research and Development (LDRD) program at Sandia National Laboratories. The work was performed during the summer months of 2002 with total funding of $65k. The intent of the project was to briefly examine a broad range of approaches to optical tagging concentrating on the wavelength range between ultraviolet (UV) and the short wavelength infrared (SWIR, {lambda} < 2{micro}m). Tagging approaches considered include such things as simple combinations of reflective and absorptive materials closely spaced in wavelength to give a high contrast over a short range of wavelengths, rare-earth oxides in transparent binders to produce a narrow absorption line hyperspectral tag, and fluorescing materials such as phosphors, dies and chemically precipitated particles. One technical approach examined in slightly greater detail was the use of fluorescing nano particles of metals and semiconductor materials. The idea was to embed such nano particles in an oily film or transparent paint binder. When pumped with a SWIR laser such as that produced by laser diodes at {lambda}=1.54{micro}m, the particles would fluoresce at slightly longer wavelengths, thereby giving a unique signal. While it is believed that optical tags are important for military, intelligence and even law enforcement applications, as a business area, tags do not appear to represent a high on return investment. Other government agencies frequently shop for existing or mature tag technologies but rarely are interested enough to pay for development of an untried technical approach. It was hoped that through a relatively small investment of laboratory R&D funds, enough technologies could be identified that a potential customers requirements could be met with a minimum of additional development work. Only time will tell if this proves to be correct.

  15. CRAO: a compact and refractive adaptive-optics

    NASA Astrophysics Data System (ADS)

    Fujishiro, Naofumi; Kitao, Eiji; Shimizu, Tomo; Matsui, Takuya; Ikeda, Yuji; Kawakita, Hideyo; Oya, Shin

    2014-08-01

    CRAO is a demonstrator of a compact and low-cost adaptive-optics (AO) with a double-pass lens configuration. Owing to its compact optical layout compared to conventional reflective AOs, the instrument size can be reduced to only 0.03 square meters. We plan to apply this miniaturization technique into future AOs on a variety of telescopes ranging from 1m- to 30m-class. CRAO is installed at a Nasmyth focus of the 1.3m Araki telescope at Koyama Astronomical Observatory in Kyoto Sangyo University. CRAO adopts a closed-loop single-conjugate system with wavelength coverage of 400 - 700 nm and the field of view of 30 arcsec. For low cost, we also employ commercial products on its wavefront sensor (WFS), deformable mirror (DM), and tip-tilt (TT) stage. CRAO is designed to improve the atmospheric seeing from 2.5 to 0.6arcsec under a typical condition at Koyama Astronomical Observatory with 12x12 subapertures in the WFS, 48 electrodes in the membrane DM and the control bandwidth of 200Hz. In order to examine key issues inherent in refractive optical system such as chromatic aberration, temperature aberration and ghost images, room and on-sky experiments are currently underway. CRAO has seen first light in May 2014, and we have confirmed that effects of chromatic aberration and ghost images induced by its refractive optics are negligible for at least TT correction. In this paper, we present experimental results as well as the design of optics, opto-mechanics and control system.

  16. Quasi-optical MEMS switching array technology

    NASA Astrophysics Data System (ADS)

    Zhang, Weikang

    During this Ph.D. dissertation research, both experimental and theoretical investigations have been conducted to develop new micro-elecro-mechancical systems (MEMS) based technologies and new device concepts for the microwave and millimeter wave frequency range. A proof-of-principle E-band (60GHz˜90GHz) MEMS switching array has been successful designed and constructed, where 400 MEMS switches form a two dimensional array on a 2inch x 2inch quartz substrate. The E-band MEMS grid array switch has demonstrated >6 dB maximum isolation at 76 GHz and >10 dB on/off contrast ratio at 70˜85 GHz. Extensive work has been carried out with the aim of developing a compact impedance matching method for quasi-optic grid arrays. A new device concept is presented, where bulk micro-machining techniques are utilized to create a new class of artificial materials with continuously variable dielectric constant for use in millimeter wave quasi-optical systems. Based on this bulk micro-machined material, two novel quasi-optical impedance transformers have been modeled, designed, and characterized, which provide ideal impedance matching for quasi-optical systems. Photonic bandgap (PBG) RF circuit models also have been studied for microwave and millimeter wave applications. During the course of this development activity, materials characteristics have been analyzed for their suitability in quasi-optical grid array circuit and RF MEMS device applications. Air bridge MEMS switches have been designed, fabricated and characterized for microwave and millimeter wave applications.

  17. LEO-to-ground optical communications link using adaptive optics correction on the OPALS downlink

    NASA Astrophysics Data System (ADS)

    Wright, Malcolm W.; Kovalik, Joseph; Morris, Jeff; Abrahamson, Matthew; Biswas, Abhijit

    2016-03-01

    The Optical PAyload for Lasercomm Science (OPALS) experiment on the International Space Station (ISS) recently demonstrated successful optical downlinks to the NASA/JPL 1-m aperture telescope at the Optical Communication Telescope Laboratory (OCTL) located near Wrightwood, CA. A large area (200 μm diameter) free space coupled avalanche photodiode (APD) detector was used to receive video and a bit patterns at 50 Mb/s. We report on a recent experiment that used an adaptive optics system at OCTL to correct for atmospherically-induced refractive index fluctuations so that the downlink from the ISS could be coupled into a single mode fiber receiver. Stable fiber coupled power was achieved over an entire pass using a self-referencing interferometer based adaptive optics system that was provided and operated by Boeing Co. and integrated to OCTL. End-to-end transmission and reconstruction of an HD video signal verified the communication performance as in the original OPALS demonstration. Coupling the signal into a single mode fiber opens the possibility for higher bandwidth and efficiency modulation schemes and serves as a pilot experiment for future implementations.

  18. Dual electro-optical modulator polarimeter based on adaptive optics scanning laser ophthalmoscope.

    PubMed

    Song, Hongxin; Qi, Xiaofeng; Zou, Weiyao; Zhong, Zhangyi; Burns, Stephen A

    2010-10-11

    We constructed a high speed and high-resolution Stokes vector retinal imaging polarimeter with dual electro-optical modulators based on adaptive optics scanning laser ophthalmoscope. By varying the voltages on the EO crystals line by line, we were able to measure over 500,000 Stokes vectors per second. We used this system in three human subjects demonstrating the capability of the system to be employed in vivo. The high speed effectively decreases the adverse impact of eye motion induced errors in polarization calculations, improving the contrast of retinal structures based on their polarization properties. PMID:20941089

  19. Extended depth of focus adaptive optics spectral domain optical coherence tomography

    PubMed Central

    Sasaki, Kazuhiro; Kurokawa, Kazuhiro; Makita, Shuichi; Yasuno, Yoshiaki

    2012-01-01

    We present an adaptive optics spectral domain optical coherence tomography (AO-SDOCT) with a long focal range by active phase modulation of the pupil. A long focal range is achieved by introducing AO-controlled third-order spherical aberration (SA). The property of SA and its effects on focal range are investigated in detail using the Huygens-Fresnel principle, beam profile measurement and OCT imaging of a phantom. The results indicate that the focal range is extended by applying SA, and the direction of extension can be controlled by the sign of applied SA. Finally, we demonstrated in vivo human retinal imaging by altering the applied SA. PMID:23082278

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

    PubMed

    Massioni, Paolo; Gilles, Luc; Ellerbroek, Brent

    2015-12-01

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

  1. Physiologically responsive, mechanically adaptive polymer optical fibers for optogenetics.

    PubMed

    Jorfi, Mehdi; Voirin, Guy; Foster, E Johan; Weder, Christoph

    2014-05-15

    The capability to deliver light to specific locations within the brain using optogenetic tools has opened up new possibilities in the field of neural interfacing. In this context, optical fibers are commonly inserted into the brain to activate or mute neurons using photosensitive proteins. While chronic optogenetic stimulation studies are just beginning to emerge, knowledge gathered in connection with electrophysiological implants suggests that the mechanical mismatch of conventional optical fibers and the cortical tissue may be a significant contributor to neuroinflammatory response. Here, we present the design and fabrication of physiologically responsive, mechanically adaptive optical fibers made of poly(vinyl alcohol) (PVA) that may mitigate this problem. Produced by a one-step wet-spinning process, the fibers display a tensile storage modulus E' of ∼7000  MPa in the dry state at 25°C and can thus readily be inserted into cortical tissue. Exposure to water causes a drastic reduction of E' to ∼35  MPa on account of modest swelling with the water. The optical properties at 470 and 590 were comparable with losses of 0.7±0.04  dB/cm at 470 nm and 0.6±0.1  dB/cm at 590 nm in the dry state and 1.1±0.1  dB/cm at 470 nm and 0.9±0.3  dB/cm at 590 nm in the wet state. The dry end of a partially switched fiber with a length of 10 cm was coupled with a light-emitting diode with an output of 10.1 mW to deliver light with a power density of >500  mW/cm2 from the wet end, which is more than sufficient to stimulate neurons in vivo. Thus, even without a low-refractive index cladding, the physiologically responsive, mechanically adaptive optical fibers presented here appear to be a very useful new tool for future optogenetic studies.

  2. Advanced Optical Technologies for Space Exploration

    NASA Technical Reports Server (NTRS)

    Clark, Natalie

    2007-01-01

    NASA Langley Research Center is involved in the development of photonic devices and systems for space exploration missions. Photonic technologies of particular interest are those that can be utilized for in-space communication, remote sensing, guidance navigation and control, lunar descent and landing, and rendezvous and docking. NASA Langley has recently established a class-100 clean-room which serves as a Photonics Fabrication Facility for development of prototype optoelectronic devices for aerospace applications. In this paper we discuss our design, fabrication, and testing of novel active pixels, deformable mirrors, and liquid crystal spatial light modulators. Successful implementation of these intelligent optical devices and systems in space, requires careful consideration of temperature and space radiation effects in inorganic and electronic materials. Applications including high bandwidth inertial reference units, lightweight, high precision star trackers for guidance, navigation, and control, deformable mirrors, wavefront sensing, and beam steering technologies are discussed. In addition, experimental results are presented which characterize their performance in space exploration systems.

  3. Image-quality metrics for characterizing adaptive optics system performance.

    PubMed

    Brigantic, R T; Roggemann, M C; Bauer, K W; Welsh, B M

    1997-09-10

    Adaptive optics system (AOS) performance is a function of the system design, seeing conditions, and light level of the wave-front beacon. It is desirable to optimize the controllable parameters in an AOS to maximize some measure of performance. For this optimization to be useful, it is necessary that a set of image-quality metrics be developed that vary monotonically with the AOS performance under a wide variety of imaging environments. Accordingly, as conditions change, one can be confident that the computed metrics dictate appropriate system settings that will optimize performance. Three such candidate metrics are presented. The first is the Strehl ratio; the second is a novel metric that modifies the Strehl ratio by integration of the modulus of the average system optical transfer function to a noise-effective cutoff frequency at which some specified image spectrum signal-to-noise ratio level is attained; and the third is simply the cutoff frequency just mentioned. It is shown that all three metrics are correlated with the rms error (RMSE) between the measured image and the associated diffraction-limited image. Of these, the Strehl ratio and the modified Strehl ratio exhibit consistently high correlations with the RMSE across a broad range of conditions and system settings. Furthermore, under conditions that yield a constant average system optical transfer function, the modified Strehl ratio can still be used to delineate image quality, whereas the Strehl ratio cannot.

  4. Fundamental limits on isoplanatic correction with multiconjugate adaptive optics.

    PubMed

    Lloyd-Hart, Michael; Milton, N Mark

    2003-10-01

    We investigate the performance of a general multiconjugate adaptive optics (MCAO) system in which signals from multiple reference beacons are used to drive several deformable mirrors in the optical beam train. Taking an analytic approach that yields a detailed view of the effects of low-order aberration modes defined over the metapupil, we show that in the geometrical optics approximation, N deformable mirrors conjugated to different ranges can be driven to correct these modes through order N with unlimited isoplanatic angle, regardless of the distribution of turbulence along the line of sight. We find, however, that the optimal deformable mirror shapes are functions of target range, so the best compensation for starlight is in general not the correction that minimizes the wave-front aberration in a laser guide beacon. This introduces focal anisoplanatism in the wave-front measurements that can be overcome only through the use of beacons at several ranges. We derive expressions for the number of beacons required to sense the aberration to arbitrary order and establish necessary and sufficient conditions on their geometry for both natural and laser guide stars. Finally, we derive an expression for the residual uncompensated error by mode as a function of field angle, target range, and MCAO system geometry.

  5. Micro-optics technology and sensor systems applications

    NASA Technical Reports Server (NTRS)

    Gal, George; Herman, B.; Anderson, W.; Whitney, R.; Morrow, H.

    1993-01-01

    The current generation of electro-optical sensors utilizing refractive and reflective optical elements require sophisticated, complex, and expensive designs. Advanced-technology-based electro-optical sensors of minimum size and weight require miniaturization of optical, electrical, and mechanical devices with an increasing trend toward integration of various components. Micro-optics technology has the potential in a number of areas to simplify optical design with improved performance. This includes internally cooled apertures, hybrid optical design, microlenses, dispersive multicolor microlenses, active dither, electronically controlled optical beam steer, and microscopic integration of micro-optics, detectors, and signal processing layers. This paper describes our approach to the development of micro-optics technology with our main emphasis for sensors applications.

  6. High-Contrast Imaging using Adaptive Optics for Extrasolar Planet Detection

    SciTech Connect

    Evans, Julia Wilhelmsen

    2006-01-01

    Direct imaging of extrasolar planets is an important, but challenging, next step in planetary science. Most planets identified to date have been detected indirectly--not by emitted or reflected light but through the effect of the planet on the parent star. For example, radial velocity techniques measure the doppler shift in the spectrum of the star produced by the presence of a planet. Indirect techniques only probe about 15% of the orbital parameter space of our solar system. Direct methods would probe new parameter space, and the detected light can be analyzed spectroscopically, providing new information about detected planets. High contrast adaptive optics systems, also known as Extreme Adaptive Optics (ExAO), will require contrasts of between 10-6 and 10-7 at angles of 4-24 λ/D on an 8-m class telescope to image young Jupiter-like planets still warm with the heat of formation. Contrast is defined as the intensity ratio of the dark wings of the image, where a planet might be, to the bright core of the star. Such instruments will be technically challenging, requiring high order adaptive optics with > 2000 actuators and improved diffraction suppression. Contrast is ultimately limited by residual static wavefront errors, so an extrasolar planet imager will require wavefront control with an accuracy of better than 1 nm rms within the low- to mid-spatial frequency range. Laboratory demonstrations are critical to instrument development. The ExAO testbed at the Laboratory for Adaptive Optics was designed with low wavefront error and precision optical metrology, which is used to explore contrast limits and develop the technology needed for an extrasolar planet imager. A state-of-the-art, 1024-actuator micro-electrical-mechanical-systems (MEMS) deformable mirror was installed and characterized to provide active wavefront control and test this novel technology. I present 6.5 x 10-8 contrast measurements with a prolate shaped pupil and

  7. 3D optical measuring technologies and systems

    NASA Astrophysics Data System (ADS)

    Chugui, Yuri V.

    2005-02-01

    The results of the R & D activity of TDI SIE SB RAS in the field of the 3D optical measuring technologies and systems for noncontact 3D optical dimensional inspection applied to atomic and railway industry safety problems are presented. This activity includes investigations of diffraction phenomena on some 3D objects, using the original constructive calculation method. The efficient algorithms for precise determining the transverse and longitudinal sizes of 3D objects of constant thickness by diffraction method, peculiarities on formation of the shadow and images of the typical elements of the extended objects were suggested. Ensuring the safety of nuclear reactors and running trains as well as their high exploitation reliability requires a 100% noncontact precise inspection of geometrical parameters of their components. To solve this problem we have developed methods and produced the technical vision measuring systems LMM, CONTROL, PROFIL, and technologies for noncontact 3D dimensional inspection of grid spacers and fuel elements for the nuclear reactor VVER-1000 and VVER-440, as well as automatic laser diagnostic COMPLEX for noncontact inspection of geometric parameters of running freight car wheel pairs. The performances of these systems and the results of industrial testing are presented and discussed. The created devices are in pilot operation at Atomic and Railway Companies.

  8. Volumetric imaging of inner retina with adaptive optics spectral-domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Yan, II; Cense, Barry; Jonnal, Ravi S.; Gao, Weihua; Jones, Steve; Olivier, Scot; Miller, Donald T.

    2007-02-01

    Adaptive optics (AO) coupled with ultra-fast spectral-domain optical coherence tomography (SD-OCT) has achieved the necessary 3D resolution, sensitivity, and speed for imaging the microscopic retina at the cellular level. While this technology has been rigorously applied to evaluating the 3D morphology of cone photoreceptors, similar detailed studies of cell-sized structures in the inner retina have yet to be undertaken. In this paper, we improve the technical performance of our AO ultrafast SD-OCT and investigate its use for imaging the microscopic inner retina, in particular the nerve fiber layer (NFL) and retinal capillary network. To maximize lateral resolution within the inner retina, focus was controlled with a high stroke, 37-actuator bimorph mirror (AOptix) that also served as the wavefront corrector of the AO. The AO system operated at a closed-loop rate of 25 Hz. The SD-OCT sub-system consisted of a superluminescent diode (λ= 842 nm, Δλ= 50 nm) and a 512 pixel line scan charge-coupled device (CCD) that acquired 72,000 A-scans/sec. Three different B-scan lengths (36, 60, and 120 A-scans/B-scan), which correspond to B-scan exposure durations of 0.5, 0.83, and 1.67 ms, were evaluated to determine the maximum B-scan length that could be tolerated without noticeable loss in image quality due to eye motion in the well fixated eye. Additional technical improvements included sub-pixel registration to remove instrument error and axial registration of the volume images. Small volume images were acquired at 2 and 7 degrees retinal eccentricity with focus systematically shifted through the retina. Small capillaries, some approaching the smallest in the human eye, were readily detected with AO SD-OCT. Appearance of the nerve fiber layer varied noticeably with depth. The most inner portion (presumably the inner limiting membrane) appeared as a thin irregular surface with little characteristic speckle noise. Within the NFL, complex striation patterns (presumably NFL

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

    PubMed

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

    2014-09-01

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

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

    PubMed Central

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

    2014-01-01

    Eye motion is a major impediment to the efficient acquisition of high resolution retinal images with the adaptive optics (AO) scanning light ophthalmoscope (AOSLO). Here we demonstrate a solution to this problem by implementing both optical stabilization and digital image registration in an AOSLO. We replaced the slow scanning mirror with a two-axis tip/tilt mirror for the dual functions of slow scanning and optical stabilization. Closed-loop optical stabilization reduced the amplitude of eye-movement related-image motion by a factor of 10–15. The residual RMS error after optical stabilization alone was on the order of the size of foveal cones: ~1.66–2.56 μm or ~0.34–0.53 arcmin with typical fixational eye motion for normal observers. The full implementation, with real-time digital image registration, corrected the residual eye motion after optical stabilization with an accuracy of ~0.20–0.25 μm or ~0.04–0.05 arcmin RMS, which to our knowledge is more accurate than any method previously reported. PMID:25401030

  11. Adaptive E-Learning Environments: Research Dimensions and Technological Approaches

    ERIC Educational Resources Information Center

    Di Bitonto, Pierpaolo; Roselli, Teresa; Rossano, Veronica; Sinatra, Maria

    2013-01-01

    One of the most closely investigated topics in e-learning research has always been the effectiveness of adaptive learning environments. The technological evolutions that have dramatically changed the educational world in the last six decades have allowed ever more advanced and smarter solutions to be proposed. The focus of this paper is to depict…

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

    SciTech Connect

    Drummond, Jack D.

    2014-03-01

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

  13. Develop techniques for ion implantation of PLZT for adaptive optics

    NASA Astrophysics Data System (ADS)

    Craig, R. A.; Batishko, C. R.; Brimhall, J. L.; Pawlewicz, W. T.; Stahl, K. A.

    1989-11-01

    Battelle Pacific Northwest Laboratory (PNL) conducted research into the preparation and characterization of ion-implanted adaptive optic elements based on lead-lanthanum-zirconate-titanate (PLZT). Over the 4-yr effort beginning FY 1985, the ability to increase the photosensitivity of PLZT and extend it to longer wavelengths was developed. The emphasis during the last two years was to develop a model to provide a basis for choosing implantation species and parameters. Experiments which probe the electronic structure were performed on virgin and implanted PLZT samples. Also performed were experiments designed to connect the developing conceptual model with the experimental results. The emphasis in FY 1988 was to extend the photosensitivity out to diode laser wavelengths. The experiments and modelling effort indicate that manganese will form appropriate intermediate energy states to achieve the longer wavelength photosensitivity. Preliminary experiments were also conducted to deposit thin film PLZT.

  14. Adaptive fiber optics collimator based on flexible hinges.

    PubMed

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

    2014-08-20

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

  15. Status of point spread function determination for Keck adaptive optics

    NASA Astrophysics Data System (ADS)

    Ragland, S.; Jolissaint, L.; Wizinowich, P.; Neyman, C.

    2014-07-01

    There is great interest in the adaptive optics (AO) science community to overcome the limitations imposed by incomplete knowledge of the point spread function (PSF). To address this limitation a program has been initiated at the W. M. Keck Observatory (WMKO) to demonstrate PSF determination for observations obtained with Keck AO science instruments. This paper aims to give a broad view of the progress achieved in this area. The concept and the implementation are briefly described. The results from on-sky on-axis NGS AO measurements using the NIRC2 science instrument are presented. On-sky performance of the technique is illustrated by comparing the reconstructed PSFs to NIRC2 PSFs. Accuracy of the reconstructed PSFs in terms of Strehl ratio and FWHM are discussed. Science cases for the first phase of science verification have been identified. More technical details of the program are presented elsewhere in the conference.

  16. Speckle image reconstruction of the adaptive optics solar images.

    PubMed

    Zhong, Libo; Tian, Yu; Rao, Changhui

    2014-11-17

    Speckle image reconstruction, in which the speckle transfer function (STF) is modeled as annular distribution according to the angular dependence of adaptive optics (AO) compensation and the individual STF in each annulus is obtained by the corresponding Fried parameter calculated from the traditional spectral ratio method, is used to restore the solar images corrected by AO system in this paper. The reconstructions of the solar images acquired by a 37-element AO system validate this method and the image quality is improved evidently. Moreover, we found the photometric accuracy of the reconstruction is field dependent due to the influence of AO correction. With the increase of angular separation of the object from the AO lockpoint, the relative improvement becomes approximately more and more effective and tends to identical in the regions far away the central field of view. The simulation results show this phenomenon is mainly due to the disparity of the calculated STF from the real AO STF with the angular dependence.

  17. Performance evaluation of a sensorless adaptive optics multiphoton microscope.

    PubMed

    Skorsetz, Martin; Artal, Pablo; Bueno, Juan M

    2016-03-01

    A wavefront sensorless adaptive optics technique was combined with a custom-made multiphoton microscope to correct for specimen-induced aberrations. A liquid-crystal-on-silicon (LCoS) modulator was used to systematically generate Zernike modes during image recording. The performance of the instrument was evaluated in samples providing different nonlinear signals and the benefit of correcting higher order aberrations was always noticeable (in both contrast and resolution). The optimum aberration pattern was stable in time for the samples here involved. For a particular depth location within the sample, the wavefront to be precompensated was independent on the size of the imaged area (up to ∼ 360 × 360 μm(2)). The mode combination optimizing the recorded image depended on the Zernike correction control sequence; however, the final images hardly differed. At deeper locations, a noticeable dominance of spherical aberration was found. The influence of other aberration terms was also compared to the effect of the spherical aberration.

  18. Implementation of modal optimization system of Subaru-188 adaptive optics

    NASA Astrophysics Data System (ADS)

    Hattori, Masayuki; Golota, Taras; Olivier, Guyon; Dinkins, Matthew; Oya, Shin; Colley, Stephen; Eldred, Michael; Watanabe, Makoto; Itoh, Meguru; Saito, Yoshihiko; Hayano, Yutaka; Takami, Hideki; Iye, Masanori

    2006-06-01

    Subaru AO-188 is a curvature adaptive optics system with 188 elements. It has been developed by NAOJ (National Astronomical Observatory of Japan) in recent years, as the upgrade from the existing 36-element AO system currently in operation at Subaru telescope. In this upgrade, the control scheme is also changed from zonal control to modal control. This paper presents development and implementation of the modal optimization system for this new AO-188. Also, we will introduce some special features and attempt in our implementation, such as consideration of resonance of deformable mirror at the lower order modes, and extension of the scheme for the optimization of the magnitude of membrane mirror in wave front sensor. Those are simple but shall be useful enhancement for the better performance to the conservative configuration with conventional modal control, and possibly useful in other extended operation modes or control schemes recently in research and development as well.

  19. Multiple Object Adaptive Optics: Mixed NGS/LGS tomography

    NASA Astrophysics Data System (ADS)

    Morris, Tim; Gendron, Eric; Basden, Alastair; Martin, Olivier; Osborn, James; Henry, David; Hubert, Zoltan; Sivo, Gaetano; Gratadour, Damien; Chemla, Fanny; Sevin, Arnaud; Cohen, Matthieu; Younger, Eddy; Vidal, Fabrice; Wilson, Richard; Batterley, Tim; Bitenc, Urban; Reeves, Andrew; Bharmal, Nazim; Raynaud, Henri-François; Kulcsar, Caroline; Conan, Jean-Marc; Guzman, Dani; De Cos Juez, Javier; Huet, Jean-Michel; Perret, Denis; Dickson, Colin; Atkinson, David; Baillie, Tom; Longmore, Andy; Todd, Stephen; Talbot, Gordon; Morris, Simon; Myers, Richard; Rousset, Gérard

    2013-12-01

    Open-loop adaptive optics has been successfully demonstrated on-sky by several groups, including the fully tomographic MOAO demonstration made using CANARY. MOAO instrumentation such as RAVEN will deliver the first astronomical science and other planned instruments aim to extend both open-loop AO performance and the number of corrected fields. Many of these planned systems rely on the use of tomographic open-loop LGS wavefront sensing. Here we present results from the combined NGS/LGS tomographic CANARY system and then compare the NGS- and LGS-based tomographic system performance. We identify the major system performance drivers, and highlight some potential routes for further exploitation of open-loop tomographic AO.

  20. Direct wavefront sensing in adaptive optical microscopy using backscattered light.

    PubMed

    Rahman, Saad A; Booth, Martin J

    2013-08-01

    Adaptive optics has been used to compensate the detrimental effects of aberrations in a range of high-resolution microscopes. We investigate how backscattered laser illumination can be used as the source for direct wavefront sensing using a pinhole-filtered Shack-Hartmann wavefront sensor. It is found that the sensor produces linear response to input aberrations for a given specimen. The gradient of this response is dependent upon experimental configuration and specimen structure. Cross sensitivity between modes is also observed. The double pass nature of the microscope system leads in general to lower sensitivity to odd-symmetry aberration modes. The results show that there is potential for use of this type of wavefront sensing in microscopes.

  1. Performance of the Keck Observatory adaptive optics system

    SciTech Connect

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

    2004-01-19

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

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

    SciTech Connect

    Poyneer, L; Veran, J P

    2010-03-29

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

  3. Measurements of contrast sensitivity by an adaptive optics visual simulator

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tatsuo; Ucikawa, Keiji

    2015-08-01

    We developed an adaptive optics visual simulator (AOVS) to study the relationship between the contrast sensitivity and higher-order wavefront aberrations of human eyes. A desired synthetic aberration was virtually generated on a subject eye by the AOVS, and red laser light was used to measure the aberrations. The contrast sensitivity was measured in a psychophysical experiment using visual stimulus patterns provided by a large-contrast-range imaging system, which included two liquid crystal displays illuminated by red light emitting diodes from the backside. The diameter of the pupil was set to 4 mm by an artificial aperture, and the retinal illuminance of the stimulus image was controlled to 10 Td. Experiments conducted with four normal subjects revealed that their contrast sensitivity to a high-spatial-frequency vertical sinusoidal grating pattern was lower in the presence of a horizontal coma aberration than in the presence of a vertical coma or no aberrations ( p < 0.02, Nagai method).

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

    PubMed

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

    2012-04-01

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

  5. Adaptive optics retinal imaging in the living mouse eye

    PubMed Central

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

    2012-01-01

    Correction of the eye’s monochromatic aberrations using adaptive optics (AO) can improve the resolution of in vivo mouse retinal images [Biss et al., Opt. Lett. 32(6), 659 (2007) and Alt et al., Proc. SPIE 7550, 755019 (2010)], but previous attempts have been limited by poor spot quality in the Shack-Hartmann wavefront sensor (SHWS). Recent advances in mouse eye wavefront sensing using an adjustable focus beacon with an annular beam profile have improved the wavefront sensor spot quality [Geng et al., Biomed. Opt. Express 2(4), 717 (2011)], and we have incorporated them into a fluorescence adaptive optics scanning laser ophthalmoscope (AOSLO). The performance of the instrument was tested on the living mouse eye, and images of multiple retinal structures, including the photoreceptor mosaic, nerve fiber bundles, fine capillaries and fluorescently labeled ganglion cells were obtained. The in vivo transverse and axial resolutions of the fluorescence channel of the AOSLO were estimated from the full width half maximum (FWHM) of the line and point spread functions (LSF and PSF), and were found to be better than 0.79 μm ± 0.03 μm (STD)(45% wider than the diffraction limit) and 10.8 μm ± 0.7 μm (STD)(two times the diffraction limit), respectively. The axial positional accuracy was estimated to be 0.36 μm. This resolution and positional accuracy has allowed us to classify many ganglion cell types, such as bistratified ganglion cells, in vivo. PMID:22574260

  6. Adaptive compressed sensing for spectral-domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Wang, Yi; Chen, Xiaodong; Wang, Ting; Li, Hongxiao; Yu, Daoyin

    2014-03-01

    Spectral-domain optical coherence tomography (SD-OCT) is a non-contact and non-invasive method for measuring the change of biological tissues caused by pathological changes of body. CCD with huge number of pixels is usually used in SD-OCT to increase the detecting depth, thus enhancing the hardness of data transmission and storage. The usage of compressed sensing (CS) in SD-OCT is able to reduce the trouble of large data transfer and storage, thus eliminating the complexity of processing system. The traditional CS uses the same sampling model for SD-OCT images of different tissue, leading to reconstruction images with different quality. We proposed a CS with adaptive sampling model. The new model is based on uniform sampling model, and the interference spectral of SD-OCT is considered to adjust the local sampling ratio. Compared with traditional CS, adaptive CS can modify the sampling model for images of different tissue according to different interference spectral, getting reconstruction images with high quality without changing sampling model.

  7. Wavefront sensorless adaptive optics fluorescence biomicroscope for in vivo retinal imaging in mice.

    PubMed

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

    2016-01-01

    Cellular-resolution in vivo fluorescence imaging is a valuable tool for longitudinal studies of retinal function in vision research. Wavefront sensorless adaptive optics (WSAO) is a developing technology that enables high-resolution imaging of the mouse retina. In place of the conventional method of using a Shack-Hartmann wavefront sensor to measure the aberrations directly, WSAO uses an image quality metric and a search algorithm to drive the shape of the adaptive element (i.e. deformable mirror). WSAO is a robust approach to AO and it is compatible with a compact, low-cost lens-based system. In this report, we demonstrated a hill-climbing algorithm for WSAO with a variable focus lens and deformable mirror for non-invasive in vivo imaging of EGFP (enhanced green fluorescent protein) labelled ganglion cells and microglia cells in the mouse retina.

  8. Wavefront sensorless adaptive optics fluorescence biomicroscope for in vivo retinal imaging in mice

    PubMed Central

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

    2015-01-01

    Cellular-resolution in vivo fluorescence imaging is a valuable tool for longitudinal studies of retinal function in vision research. Wavefront sensorless adaptive optics (WSAO) is a developing technology that enables high-resolution imaging of the mouse retina. In place of the conventional method of using a Shack-Hartmann wavefront sensor to measure the aberrations directly, WSAO uses an image quality metric and a search algorithm to drive the shape of the adaptive element (i.e. deformable mirror). WSAO is a robust approach to AO and it is compatible with a compact, low-cost lens-based system. In this report, we demonstrated a hill-climbing algorithm for WSAO with a variable focus lens and deformable mirror for non-invasive in vivo imaging of EGFP (enhanced green fluorescent protein) labelled ganglion cells and microglia cells in the mouse retina. PMID:26819812

  9. 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.

  10. Status of the PALM-3000 high order adaptive optics instrument

    NASA Astrophysics Data System (ADS)

    Burruss, Rick S.; Dekany, Richard G.; Roberts, Jennifer E.; Shelton, J. C.; Wallace, J. K.; Tesch, Jonathan A.; Palmer, Dean L.; Hale, David; Bartos, Randall; Rykoski, Kevin M.; Heffner, Carolyn M.; Eriksen, Jamey E.; Vescelus, Fred

    2014-07-01

    We report on the status of PALM-3000, the second generation adaptive optics instrument for the 5.1 meter Hale telescope at Palomar Observatory. PALM-3000 was released as a facility class instrument in October 2011, and has since been used on the Hale telescope a total of over 250 nights. In the past year, the PALM-3000 team introduced several instrument upgrades, including the release of the 32x32 pupil sampling mode which allows for correction on fainter guide stars, the upgrade of wavefront sensor relay optics, the diagnosis and repair of hardware problems, and the release of software improvements. We describe the performance of the PALM-3000 instrument as a result of these upgrades, and provide on-sky results. In the 32x32 pupil sampling mode (15.8 cm per subaperture), we have achieved K-band strehl ratios as high as 11% on a 14.4 mv star, and in the 64x64 pupil sampling mode (8.1 cm per subaperture), we have achieved K-band strehl ratios as high as 86% on stars brighter than 7th mv.

  11. Design of the Subaru laser guide star adaptive optics module

    NASA Astrophysics Data System (ADS)

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

    2004-10-01

    The laser guide star adaptive optics (AO) module for the Subaru Telescope will be installed at the f/13.9 IR Nasmyth focus, and provides the compensated image for the science instrument without change of the focal ratio. The optical components are mounted on an optical bench, and the flexure depending on the telescope pointing is eliminated. The transferred field of view for the science instrument is 2 arcmin diameter, but a 2.7 arcmin diameter field is available for tip-tilt sensing. The science path of the AO module contains five mirrors, including a pair of off-axis parabolic mirrors and a deformable mirror. It has also three additional mirrors for an image rotator. The AO module has a visible 188-element curvature based wavefront sensor (WFS) with photon-counting avalanche photodiode (APD) modules. It measures high-order terms of wavefront using either of a single laser (LGS) or natural guide star (NGS) within a 2 arcmin diameter field. The AO module has also a visible 2 x 2 sub-aperture Shack-Hartmann WFS with 16 APD modules. It measures tip-tilt and slow defocus terms of wavefront by using a single NGS within a 2.7 arcmin diameter field when a LGS is used for high-order wavefront sensing. The module has also an infrared 2 x 2 sub-aperture Shack-Hartmann WFS with a HgCdTe array as an option. Both high- and low-order visible WFSs have their own guide star acquisition units with two steering fold mirrors. The AO module has also a source simulator. It simulates LGS and NGS beams, simultaneously, with and without atmospheric turbulence by two turbulent layer at about 0 and 6 km altitudes, and reproduces the isoplanatism and the cone effect for the LGS beam.

  12. Retinal axial focusing and multi-layer imaging with a liquid crystal adaptive optics camera

    NASA Astrophysics Data System (ADS)

    Liu, Rui-Xue; Zheng, Xian-Liang; Li, Da-Yu; Xia, Ming-Liang; Hu, Li-Fa; Cao, Zhao-Liang; Mu, Quan-Quan; Xuan, Li

    2014-09-01

    With the help of adaptive optics (AO) technology, cellular level imaging of living human retina can be achieved. Aiming to reduce distressing feelings and to avoid potential drug induced diseases, we attempted to image retina with dilated pupil and froze accommodation without drugs. An optimized liquid crystal adaptive optics camera was adopted for retinal imaging. A novel eye stared system was used for stimulating accommodation and fixating imaging area. Illumination sources and imaging camera kept linkage for focusing and imaging different layers. Four subjects with diverse degree of myopia were imaged. Based on the optical properties of the human eye, the eye stared system reduced the defocus to less than the typical ocular depth of focus. In this way, the illumination light can be projected on certain retina layer precisely. Since that the defocus had been compensated by the eye stared system, the adopted 512 × 512 liquid crystal spatial light modulator (LC-SLM) corrector provided the crucial spatial fidelity to fully compensate high-order aberrations. The Strehl ratio of a subject with -8 diopter myopia was improved to 0.78, which was nearly close to diffraction-limited imaging. By finely adjusting the axial displacement of illumination sources and imaging camera, cone photoreceptors, blood vessels and nerve fiber layer were clearly imaged successfully.

  13. Extreme Adaptive Optics Testbed: High Contrast Measurements with a MEMS Deformable Mirror

    SciTech Connect

    Evans, J W; Morzinski, K; Reza, L; Severson, S; Poyneer, L; Macintosh, B; Dillon, D; Sommargren, G

    2005-08-16

    ''Extreme'' adaptive optics systems are optimized for ultra-high-contrast applications, such as ground-based extrasolar planet detection. The Extreme Adaptive Optics Testbed at UC Santa Cruz is being used to investigate and develop technologies for high-contrast imaging, especially wavefront control. We use a simple optical design to minimize wavefront error and maximize the experimentally achievable contrast. A phase shifting diffraction interferometer (PSDI) measures wavefront errors with sub-nm precision and accuracy for metrology and wavefront control. Previously, we have demonstrated RMS wavefront errors of <1.5 nm and a contrast of >10{sup 7} over a substantial region using a shaped pupil without a deformable mirror. Current work includes the installation and characterization of a 1024-actuator Micro-Electro-Mechanical-Systems (MEMS) deformable mirror, manufactured by Boston Micro-Machines for active wavefront control. Using the PSDI as the wavefront sensor we have flattened the deformable mirror to <1 nm within the controllable spatial frequencies and measured a contrast in the far field of >10{sup 6}. 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. Ultimately this testbed will be used to test all aspects of the system architecture for an extrasolar planet-finding AO system.

  14. Performance Modeling for the RAVEN Multi-Object Adaptive Optics Demonstrator

    NASA Astrophysics Data System (ADS)

    Andersen, David R.; Jackson, Kate J.; Blain, Célia; Bradley, Colin; Correia, Carlos; Ito, Meguru; Lardière, Olivier; Véran, Jean-Pierre

    2012-05-01

    RAVEN will be a Multi-Object Adaptive Optics (MOAO) technology and science demonstrator on the Subaru telescope. The baseline design calls for three natural guide star (NGS) wavefront sensors (WFS) and two science pickoff arms that will patrol a ~2' diameter field of regard (FOR). Sky coverage is an important consideration, because RAVEN is both a technical and science demonstrator. Early-stage simulation of RAVEN's performance is critical in establishing that the key science requirement can be met. That is, 30% of the energy of an unresolved point-spread function (PSF) be ensquared within a 140 mas slit using existing WFS camera and deformable mirror (DM) technology. The system was simulated with two independent modeling tools, MAOS and OOMAO, which were in excellent agreement. It was established that RAVEN will be an order 10 × 10 adaptive optics (AO) system by examining the tradeoffs between performance, sky coverage, and WFS field of view. The 30% ensquared-energy (EE) requirement will be met with three NGSs and will exceed 40% if the Subaru Laser Guide Star (LGS) is used on-axis (assuming median image quality). This is also true for NGSs as faint as mR = 14.5.

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

    PubMed

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

    2011-06-01

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

  16. Development of active/adaptive lightweight optics for the next generation of telescopes

    NASA Astrophysics Data System (ADS)

    Ghigo, M.; Basso, S.; Citterio, O.; Mazzoleni, F.; Vernani, D.

    2006-02-01

    The future large optical telescopes will have such large dimensions to require innovative technical solutions either in the engineering and optical fields. Their optics will have dimensions ranging from 30 to 100 m. and will be segmented. It is necessary to develop a cost effective industrial process, fast and efficient, to create the thousands of segments neeededs to assemble the mirrors of these instruments. INAF-OAB (Astronomical Observatory of Brera) is developing with INAF-Arcetri (Florence Astronomical Observatory) a method of production of lightweight glass optics that is suitable for the manufacturing of these segments. These optics will be also probably active and therefore the segments have to be thin, light and relatively flexible. The same requirements are valid also for the secondary adaptive mirrors foreseen for these telescopes and that therefore will benefit from the same technology. The technique under investigation foresees the thermal slumping of thin glass segments using a high quality ceramic mold (master). The sheet of glass is placed onto the mold and then, by means of a suitable thermal cycle, the glass is softened and its shape is changed copying the master shape. At the end of the slumping the correction of the remaining errors will be performed using the Ion Beam Figuring technique, a non-contact deterministic technique. To reduce the time spent for the correction it will be necessary to have shape errors on the segments as small as possible. A very preliminary series of experiments already performed on reduced size segments have shown that it is possible to copy a master shape with high accuracy (few microns PV) and it is very likely that copy accuracies of 1 micron or less are possible. The paper presents in detail the concepts of the proposed process and describes our current efforts that are aimed at the production of a scaled demonstrative adaptive segment of 50 cm of diameter.

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

    NASA Astrophysics Data System (ADS)

    Nightingale, Alice M.

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

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

    SciTech Connect

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

    2001-07-31

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

  19. High-accuracy wavefront control for retinal imaging with Adaptive-Influence-Matrix Adaptive Optics

    PubMed Central

    Zou, Weiyao; Burns, Stephen A.

    2010-01-01

    We present an iterative technique for improving adaptive optics (AO) wavefront correction for retinal imaging, called the Adaptive-Influence-Matrix (AIM) method. This method is based on the fact that the deflection-to-voltage relation of common deformable mirrors used in AO are nonlinear, and the fact that in general the wavefront errors of the eye can be considered to be composed of a static, non-zero wavefront error (such as the defocus and astigmatism), and a time-varying wavefront error. The aberrated wavefront is first corrected with a generic influence matrix, providing a mirror compensation figure for the static wavefront error. Then a new influence matrix that is more accurate for the specific static wavefront error is calibrated based on the mirror compensation figure. Experimental results show that with the AIM method the AO wavefront correction accuracy can be improved significantly in comparison to the generic AO correction. The AIM method is most useful in AO modalities where there are large static contributions to the wavefront aberrations. PMID:19997241

  20. Optical spectroscopy with a near-single-mode fiber-feed and adaptive optics

    NASA Astrophysics Data System (ADS)

    Ge, Jian; Angel, J. Roger P.; Shelton, J. Christopher

    1998-07-01

    We report on first astronomical results with a cross-dispersed optical echelle spectrograph fed by a near single-mode fiber. We also present on a novel design of a new adaptive optics (AO) optimized fiber-fed cross-dispersed echelle spectrograph. The spectrograph is designed to match with AO corrected images in the optical bands provided by such as the Mt. Wilson 100 inch, Starfire Optical Range 3.5 m AO telescopes. Ultimately, it will be installed at the 6.5 m MMT, when this has high resolution AO correcting the optical spectrum. The spectrograph, fed by a 10 micron fused silica fiber, is unique in that the entire spectrum from 0.4 micron to 1.0 micron will be almost completely covered at resolution 200,000 in one exposure. The detector is a 2k X 4k AR coated back illuminated CCD with 15 micron pixel size. The close order spacing allowed by the sharp AO image makes the full cover possible. A 250 X 125 mm(superscript 2) Milton Roy R2 echelle grating with 23.2 grooves mm(superscript -1) and a blaze angle of 63.5 deg provides main dispersion. A double pass BK7 prism with 21 deg wedge angle provides cross dispersion, covering the spectrum from order 193 to 77. The spectrograph is used in the quasi- Littrow configuration with an off-axis Maksutov collimator/camera. The fiber feeds the AO corrected beams from the telescope Cassegrain focus to the spectrograph, which is set up on an optical bench. The spectrograph will be used mainly to study line profiles of solar type stars, to explore problems of indirect detection of planets and also study interstellar medium, circumstellar medium and metal abundance and isotopic ratios of extremely metal-poor stars.

  1. Important position of optical fibre technology in shipboard equipment construction

    NASA Astrophysics Data System (ADS)

    Zhao, Enyi

    1991-08-01

    The application of optical fiber technology on board naval vessels is discussed, with emphasis on the optical fiber image guides and optical fiber communication. (1) Optical fiber image guides, when integrated with traditional technology, may give rise to a new type of observation device with more extensive capabilities, and may provide a solution to some tricky problems in the field of shipboard optical technology. (2) The use of optical fiber image guides may greatly improve the operation efficiency of shipboard weapon systems, and may lead to a revolutionary change in the field of tactical weapons competition. (3) A well- developed optical fiber communication network will modernize the internal communication within a ship. Such a network constitutes a prototype for future intercom systems.

  2. Bridge SHM system based on fiber optical sensing technology

    NASA Astrophysics Data System (ADS)

    Li, Sheng; Fan, Dian; Fu, Jiang-hua; Huang, Xing; Jiang, De-sheng

    2015-09-01

    The latest progress of our lab in recent 10 years on the area of bridge structural health monitoring (SHM) based on optical fiber sensing technology is introduced. Firstly, in the part of sensing technology, optical fiber force test-ring, optical fiber vibration sensor, optical fiber smart cable, optical fiber prestressing loss monitoring method and optical fiber continuous curve mode inspection system are developed, which not only rich the sensor types, but also provides new monitoring means that are needed for the bridge health monitoring system. Secondly, in the optical fiber sensing network and computer system platform, the monitoring system architecture model is designed to effectively meet the integration scale and effect requirement of engineering application, especially the bridge expert system proposed integration of sensing information and informatization manual inspection to realize the mode of multi index intelligence and practical monitoring, diagnosis and evaluation. Finally, the Jingyue bridge monitoring system as the representative, the research on the technology of engineering applications are given.

  3. A Reflective Gaussian Coronagraph for Extreme Adaptive Optics: Laboratory Performance

    NASA Astrophysics Data System (ADS)

    Park, Ryeojin; Close, Laird M.; Siegler, Nick; Nielsen, Eric L.; Stalcup, Thomas

    2006-11-01

    We report laboratory results of a coronagraphic test bench to assess the intensity reduction differences between a ``Gaussian'' tapered focal plane coronagraphic mask and a classical hard-edged ``top hat'' function mask at extreme adaptive optics (ExAO) Strehl ratios of ~94%. However, unlike a traditional coronagraph design, we insert a reflective focal plane mask at 45° to the optical axis. We also use an intermediate secondary mask (mask 2) before a final image in order to block additional mask-edge-diffracted light. The test bench simulates the optical train of ground-based telescopes (in particular, the 8.1 m Gemini North Telescope). It includes one spider vane, different mask radii (r = 1.9λ/D, 3.7λ/D, and 7.4λ/D), and two types of reflective focal plane masks (hard-edged top-hat and Gaussian tapered profiles). In order to investigate the relative performance of these competing coronagraphic designs with regard to extrasolar planet detection sensitivity, we utilize the simulation of realistic extrasolar planet populations (Nielsen et al.). With an appropriate translation of our laboratory results to expected telescope performance, a Gaussian tapered mask radius of 3.7λ/D with an additional mask (mask 2) performs best (highest planet detection sensitivity). For a full survey with this optimal design, the simulation predicts that ~30% more planets would be detected than with a top-hat function mask of similar size with mask 2. Using the best design, the point contrast ratio between the stellar point-spread function (PSF) peak and the coronagraphic PSF at 10λ/D (0.4" in the H band if D = 8.1 m) is ~10 times higher than a classical Lyot top-hat coronagraph. Hence, we find that a Gaussian apodized mask with an additional blocking mask is superior (~10 times higher contrast) to the use of a classical Lyot coronagraph for ExAO-like Strehl ratios.

  4. Application of optical interconnect technology at Lawrence Livermore National Laboratory

    SciTech Connect

    Haigh, R.E.; Lowry, M.E.; McCammon, K.; Hills, R.; Mitchell, R.; Sweider, D.

    1995-08-10

    Optical interconnects will be required to meet the information bandwidth requirements of future communication and computing applications. At Lawrence Livermore National Laboratory, the authors are involved in applying optical interconnect technologies in two distinct application areas: Multi-Gigabit/sec Computer Backplanes and Gigabit/sec Wide Area Networking using Wavelength Division Multiplexing. In this paper, the authors discuss their efforts to integrate optical interconnect technologies into prototype computing and communication systems.

  5. Method for removing tilt control in adaptive optics systems

    DOEpatents

    Salmon, Joseph Thaddeus

    1998-01-01

    A new adaptive optics system and method of operation, whereby the method removes tilt control, and includes the steps of using a steering mirror to steer a wavefront in the desired direction, for aiming an impinging aberrated light beam in the direction of a deformable mirror. The deformable mirror has its surface deformed selectively by means of a plurality of actuators, and compensates, at least partially, for existing aberrations in the light beam. The light beam is split into an output beam and a sample beam, and the sample beam is sampled using a wavefront sensor. The sampled signals are converted into corresponding electrical signals for driving a controller, which, in turn, drives the deformable mirror in a feedback loop in response to the sampled signals, for compensating for aberrations in the wavefront. To this purpose, a displacement error (gradient) of the wavefront is measured, and adjusted by a modified gain matrix, which satisfies the following equation: G'=(I-X(X.sup.T X).sup.-1 X.sup.T)G(I-A)

  6. Method for removing tilt control in adaptive optics systems

    DOEpatents

    Salmon, J.T.

    1998-04-28

    A new adaptive optics system and method of operation are disclosed, whereby the method removes tilt control, and includes the steps of using a steering mirror to steer a wavefront in the desired direction, for aiming an impinging aberrated light beam in the direction of a deformable mirror. The deformable mirror has its surface deformed selectively by means of a plurality of actuators, and compensates, at least partially, for existing aberrations in the light beam. The light beam is split into an output beam and a sample beam, and the sample beam is sampled using a wavefront sensor. The sampled signals are converted into corresponding electrical signals for driving a controller, which, in turn, drives the deformable mirror in a feedback loop in response to the sampled signals, for compensating for aberrations in the wavefront. To this purpose, a displacement error (gradient) of the wavefront is measured, and adjusted by a modified gain matrix, which satisfies the following equation: G{prime} = (I{minus}X(X{sup T} X){sup {minus}1}X{sup T})G(I{minus}A). 3 figs.

  7. Adaptive optics images. III. 87 Kepler objects of interest

    SciTech Connect

    Dressing, Courtney D.; Dupree, Andrea K.; Adams, Elisabeth R.; Kulesa, Craig; McCarthy, Don

    2014-11-01

    The Kepler mission has revolutionized our understanding of exoplanets, but some of the planet candidates identified by Kepler may actually be astrophysical false positives or planets whose transit depths are diluted by the presence of another star. Adaptive optics images made with ARIES at the MMT of 87 Kepler Objects of Interest place limits on the presence of fainter stars in or near the Kepler aperture. We detected visual companions within 1'' for 5 stars, between 1'' and 2'' for 7 stars, and between 2'' and 4'' for 15 stars. For those systems, we estimate the brightness of companion stars in the Kepler bandpass and provide approximate corrections to the radii of associated planet candidates due to the extra light in the aperture. For all stars observed, we report detection limits on the presence of nearby stars. ARIES is typically sensitive to stars approximately 5.3 Ks magnitudes fainter than the target star within 1'' and approximately 5.7 Ks magnitudes fainter within 2'', but can detect stars as faint as ΔKs = 7.5 under ideal conditions.

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

    PubMed

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

    2014-12-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  10. Optical techniques to understand biofunctional adaptation in human dentine

    NASA Astrophysics Data System (ADS)

    Kishen, Anil; Asundi, Anand K.

    2004-08-01

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

  11. Performance evaluation of a sensorless adaptive optics multiphoton microscope.

    PubMed

    Skorsetz, Martin; Artal, Pablo; Bueno, Juan M

    2016-03-01

    A wavefront sensorless adaptive optics technique was combined with a custom-made multiphoton microscope to correct for specimen-induced aberrations. A liquid-crystal-on-silicon (LCoS) modulator was used to systematically generate Zernike modes during image recording. The performance of the instrument was evaluated in samples providing different nonlinear signals and the benefit of correcting higher order aberrations was always noticeable (in both contrast and resolution). The optimum aberration pattern was stable in time for the samples here involved. For a particular depth location within the sample, the wavefront to be precompensated was independent on the size of the imaged area (up to ∼ 360 × 360 μm(2)). The mode combination optimizing the recorded image depended on the Zernike correction control sequence; however, the final images hardly differed. At deeper locations, a noticeable dominance of spherical aberration was found. The influence of other aberration terms was also compared to the effect of the spherical aberration. PMID:26469361

  12. High-contrast, adaptive-optics simulations for HARMONI

    NASA Astrophysics Data System (ADS)

    Gladysz, Szymon; Thatte, Niranjan A.; Salter, Graeme; Clarke, Fraser; Tecza, Matthias; Jolissaint, Laurent; Galle, Roberto Baena

    2011-09-01

    HARMONI is a proposed visible and near-infrared integral field spectrograph for the European Extremely Large Telescope. We are exploring the potential of using HARMONI for high-contrast science, e.g. observations of exoplanets. Although HARMONI is not fed by extreme adaptive optics we show that substantial contrasts can be achieved by combining single-conjugate AO with coronagraphy and post-processing of the hyperspectral data cube using spectral deconvolution. HARMONI will be well suited for follow-up spectroscopy of planets detected by 8m class instruments, emphasizing their characterisation. We implement models of telescope aberrations: due to wind buffeting on M1, due to windshake on M2, due to rolled segment edges, as well as the ones resulting from M1 phasing and individual segment warping affected by thermal and gravity effects. Additionally, we investigate the impact of post-AO differential aberrations. We also look at possible improvements to spectral deconvolution which is our method of choice for data post-processing. Finally, we make predictions of achievable contrast which translates to the ability to characterise various types of exoplanets in detail.

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

    NASA Astrophysics Data System (ADS)

    Fraga, Luciano; Kunder, Andrea; Tokovinin, Andrei

    2013-06-01

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

  14. AdapTube: Adaptive Optics animations for tutorial purpose

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  15. Adopt or Adapt: Sanitation Technology Choices in Urbanizing Malawi.

    PubMed

    Chunga, Richard M; Ensink, Jeroen H J; Jenkins, Marion W; Brown, Joe

    2016-01-01

    This paper presents the results of a mixed-methods study examining adaptation strategies that property owners in low-income, rapidly urbanizing areas in Malawi adopt to address the limitations of pit latrines, the most common method of disposing human excreta. A particular challenge is lack of space for constructing new latrines as population density increases: traditional practice has been to cap full pits and simply move to a new site, but increasing demands on space require new approaches to extend the service life of latrines. In this context, we collected data on sanitation technology choices from January to September 2013 through 48 in-depth interviews and a stated preference survey targeting 1,300 property owners from 27 low-income urban areas. Results showed that property owners with concern about space for replacing pit latrines were 1.8 times more likely to select pit emptying service over the construction of new pit latrines with a slab floor (p = 0.02) but there was no significant association between concern about space for replacing pit latrines and intention to adopt locally promoted, novel sanitation technology known as ecological sanitation (ecosan). Property owners preferred to adapt existing, known technology by constructing replacement pit latrines on old pit latrine locations, reducing the frequency of replacing pit latrines, or via emptying pit latrines when full. This study highlights potential challenges to adoption of wholly new sanitation technologies, even when they present clear advantages to end users. To scale, alternative sanitation technologies for rapidly urbanising cities should offer clear advantages, be affordable, be easy to use when shared among multiple households, and their design should be informed by existing adaptation strategies and local knowledge.

  16. Adopt or Adapt: Sanitation Technology Choices in Urbanizing Malawi

    PubMed Central

    Chunga, Richard M.; Ensink, Jeroen H. J.; Jenkins, Marion W.; Brown, Joe

    2016-01-01

    This paper presents the results of a mixed-methods study examining adaptation strategies that property owners in low-income, rapidly urbanizing areas in Malawi adopt to address the limitations of pit latrines, the most common method of disposing human excreta. A particular challenge is lack of space for constructing new latrines as population density increases: traditional practice has been to cap full pits and simply move to a new site, but increasing demands on space require new approaches to extend the service life of latrines. In this context, we collected data on sanitation technology choices from January to September 2013 through 48 in-depth interviews and a stated preference survey targeting 1,300 property owners from 27 low-income urban areas. Results showed that property owners with concern about space for replacing pit latrines were 1.8 times more likely to select pit emptying service over the construction of new pit latrines with a slab floor (p = 0.02) but there was no significant association between concern about space for replacing pit latrines and intention to adopt locally promoted, novel sanitation technology known as ecological sanitation (ecosan). Property owners preferred to adapt existing, known technology by constructing replacement pit latrines on old pit latrine locations, reducing the frequency of replacing pit latrines, or via emptying pit latrines when full. This study highlights potential challenges to adoption of wholly new sanitation technologies, even when they present clear advantages to end users. To scale, alternative sanitation technologies for rapidly urbanising cities should offer clear advantages, be affordable, be easy to use when shared among multiple households, and their design should be informed by existing adaptation strategies and local knowledge. PMID:27532871

  17. Adopt or Adapt: Sanitation Technology Choices in Urbanizing Malawi.

    PubMed

    Chunga, Richard M; Ensink, Jeroen H J; Jenkins, Marion W; Brown, Joe

    2016-01-01

    This paper presents the results of a mixed-methods study examining adaptation strategies that property owners in low-income, rapidly urbanizing areas in Malawi adopt to address the limitations of pit latrines, the most common method of disposing human excreta. A particular challenge is lack of space for constructing new latrines as population density increases: traditional practice has been to cap full pits and simply move to a new site, but increasing demands on space require new approaches to extend the service life of latrines. In this context, we collected data on sanitation technology choices from January to September 2013 through 48 in-depth interviews and a stated preference survey targeting 1,300 property owners from 27 low-income urban areas. Results showed that property owners with concern about space for replacing pit latrines were 1.8 times more likely to select pit emptying service over the construction of new pit latrines with a slab floor (p = 0.02) but there was no significant association between concern about space for replacing pit latrines and intention to adopt locally promoted, novel sanitation technology known as ecological sanitation (ecosan). Property owners preferred to adapt existing, known technology by constructing replacement pit latrines on old pit latrine locations, reducing the frequency of replacing pit latrines, or via emptying pit latrines when full. This study highlights potential challenges to adoption of wholly new sanitation technologies, even when they present clear advantages to end users. To scale, alternative sanitation technologies for rapidly urbanising cities should offer clear advantages, be affordable, be easy to use when shared among multiple households, and their design should be informed by existing adaptation strategies and local knowledge. PMID:27532871

  18. Opportunities in Application Design Using Optical Technology.

    ERIC Educational Resources Information Center

    Bowers, Richard A.

    1987-01-01

    Discusses the capabilities of optical data disk systems to merge different types of media, and the need to incorporate these capabilities into new information products. Guidelines for creating a profitable optical data disk product are outlined. (CLB)

  19. Optical figuring specifications for thin shells to be used in adaptive telescope mirrors

    NASA Astrophysics Data System (ADS)

    Riccardi, A.

    2006-06-01

    The present work describes the guidelines to define the optical figuring specifications for optical manufacturing of thin shells in terms of figuring error power spectrum (and related rms vs scale distributon) to be used in adaptive optics correctors with force actuators like Deformable Secondary Mirrors (DSM). In particular the numerical example for a thin shell for a VLT DSM is considered.

  20. Optics vs copper: from the perspective of "Thunderbolt" interconnect technology

    NASA Astrophysics Data System (ADS)

    Cheng, Hengju; Krause, Christine; Ko, Jamyuen; Gao, Miaobin; Liu, Guobin; Wu, Huichin; Qi, Mike; Lam, Chun-Chit

    2013-02-01

    Interconnect technology has been progressed at a very fast pace for the past decade. The signaling rates have steadily increased from 100:Mb/s to 25Gb/s. In every generation of interconnect technology evolution, optics always seems to take over at first, however, at the end, the cost advantage of copper wins over. Because of this, optical interconnects are limited to longer distance links where the attenuation in copper cable is too large for the integrated circuits to compensate. Optical interconnect has long been viewed as the premier solution in compared with copper interconnect. With the release of Thunderbolt technology, we are entering a new era in consumer electronics that runs at 10Gb/s line rate (20Gb/s throughput per connector interface). Thunderbolt interconnect technology includes both active copper cables and active optical cables as the transmission media which have very different physical characteristics. In order for optics to succeed in consumer electronics, several technology hurdles need to be cleared. For example, the optical cable needs to handle the consumer abuses such as pinch and bend. Also, the optical engine used in the active optical cable needs to be physically very small so that we don't change the looks and feels of the cable/connector. Most importantly, the cost of optics needs to come down significantly to effectively compete with the copper solution. Two interconnect technologies are compared and discussed on the relative cost, power consumption, form factor, density, and future scalability.

  1. Marginal adaptation analysis performed with en face optical coherence tomography in fixed partial dentures

    NASA Astrophysics Data System (ADS)

    Sinescu, Cosmin; Negrutiu, Meda Lavinia; Antonie, Sergiu; Dobre, George; Bradu, Adrian; Hughes, Michael; Rominu, Mihai; Podoleanu, Adrian Gh.

    2009-02-01

    Frameworks for fixed partial denture made out of dental alloys thought classic techniques currently involve many errors like marginal and internal gaps. The aim of this study is to present alternative technologies in making frameworks from dental alloys using selective laser sintering/ selective laser melting (SLS/ SLM) and to investigate the marginal adaptation of the fixed dental prostheses using the en face optical coherence tomography. These procedures imply the use of a scanning device PROBIS, SMART OPTICS with the help of 3D Dental Scanner software. For digitizing the 3D model we used the Dental Wings Kunde Software. The files obtained were sent to a SLS/ SLM machine, Hint-Els rapidPro, where the CoCr powder was sintered/melt by selectively consolidating successive layers of powder material on top of each other, using thermal energy supplied by a focused and computer controlled laser beam. Through this technique can be produced up to 80 pieces in only one step. A parallel between the classic casting technique and this new technology reveal the least has several advantages: fast finishing time, excellent marginal and internal fit, biocompatibility and superior chemical properties. SLS/ SLM proved to be a promising technology that may overcome the classic ones, because of the superior marginal fit of the fixed dental prostheses to the teeth.

  2. Covert optically-scanning enhanced zoom pinhole lens technology

    NASA Astrophysics Data System (ADS)

    Rana, H. S.

    2007-10-01

    Lens technology has been developed that enables a scene to be scanned optically whilst the lens remains stationary. The covert optically-scanning enhanced (COSE) pinhole lens technology also has the option of incorporating a zoom capability. This allows any target in the scene to be isolated and zoomed onto for further scrutiny. The COSE lens has an external stationary entrance pupil. The operation of the lens may be visualized as optically pivoting about this pupil plane whilst scanning the scene but physically remaining stationary. A technology demonstrator has been built and its performance is discussed. Further developments of the COSE technology are also discussed.

  3. Development of optical fiber technology in Poland 2015

    NASA Astrophysics Data System (ADS)

    Romaniuk, Ryszard S.; Wójcik, Waldemar

    2015-12-01

    The paper is a digest of works presented during the XVIth National Symposium on Optical Fibres and Their Applications. The Symposium is organized since 1976. OFTA 2015 was organized by Optical Fibre Laboratory of the Faculty of Chemistry at University of Maria Curie Skłodowska, and Institute of Electronics and Information Technology of Lublin University of Technology, in Nałęczów on 22-25 September 2015. The meeting has gathered around 120 participants who presented 85 research and technical papers. The Symposium organized every 18 months is a good portrait of optical fibre technology development in Poland at university laboratories, governmental institutes, company R&D laboratories, etc. Topical tracks of the Symposium were: optical and photonic materials, technology of classical, tailored and structural photonic optical fibres, light propagation physics in optical fibres, passive and active optical fibre components, optical fibre sensors, passive and active optical fibre networks, optical fibre amplifiers and lasers, optical fibre network issues: modulation, architectures, economy, etc.

  4. Smart Structures with Fibre-Optic Technologies

    SciTech Connect

    Del Grosso, Andrea; Zangani, Donato; Messervey, Thomas

    2008-07-08

    A number of smart structures have been proposed, and some of them realized, to reduce the effect that seismic motions induce on the structure themselves. In particular, active and semi-active control devices have been studied for being applied to buildings and bridges in seismic prone regions. The heart of the application for these devices consists of a network of sensors and computational nodes that produces the input to the actuating mechanisms. Despite the initial enthusiasm for these developments, only a few practical applications involving active devices have been implemented to-date, the main reason residing in questions concerning the reliability of active systems over time. Nevertheless, the allocation of sensory systems and computational intelligence in structures subjected to earthquakes can provide very important information on the real structural behavior, provide self-diagnosis functions after events, and allow for reliability estimates of critical components. The paper reviews several recently developed sensory devices and diagnostic algorithms that may be applied to existing structures or embedded in new ones for the above purpose. Special emphasis will be given to fibre optic technology and its applications.

  5. IR performance study of an adaptive coded aperture "diffractive imaging" system employing MEMS "eyelid shutter" technologies

    NASA Astrophysics Data System (ADS)

    Mahalanobis, A.; Reyner, C.; Patel, H.; Haberfelde, T.; Brady, David; Neifeld, Mark; Kumar, B. V. K. Vijaya; Rogers, Stanley

    2007-09-01

    Adaptive coded aperture sensing is an emerging technology enabling real time, wide-area IR/visible sensing and imaging. Exploiting unique imaging architectures, adaptive coded aperture sensors achieve wide field of view, near-instantaneous optical path repositioning, and high resolution while reducing weight, power consumption and cost of air- and space born sensors. Such sensors may be used for military, civilian, or commercial applications in all optical bands but there is special interest in diffraction imaging sensors for IR applications. Extension of coded apertures from Visible to the MWIR introduces the effects of diffraction and other distortions not observed in shorter wavelength systems. A new approach is being developed under the DARPA/SPO funded LACOSTE (Large Area Coverage Optical search-while Track and Engage) program, that addresses the effects of diffraction while gaining the benefits of coded apertures, thus providing flexibility to vary resolution, possess sufficient light gathering power, and achieve a wide field of view (WFOV). The photonic MEMS-Eyelid "sub-aperture" array technology is currently being instantiated in this DARPA program to be the heart of conducting the flow (heartbeat) of the incoming signal. However, packaging and scalability are critical factors for the MEMS "sub-aperture" technology which will determine system efficacy as well as military and commercial usefulness. As larger arrays with 1,000,000+ sub-apertures are produced for this LACOSTE effort, the available Degrees of Freedom (DOF) will enable better spatial resolution, control and refinement on the coding for the system. Studies (SNR simulations) will be performed (based on the Adaptive Coded Aperture algorithm implementation) to determine the efficacy of this diffractive MEMS approach and to determine the available system budget based on simulated bi-static shutter-element DOF degradation (1%, 5%, 10%, 20%, etc..) trials until the degradation level where it is

  6. Development of laser guide stars and adaptive optics for large astronomical telescopes

    SciTech Connect

    Max, C.E.; Avicola, K.; Bissinger, H.; Brase, J.M.; Gavel, D.T.; Friedman, H.; Morris, J.R.; Olivier, S.S.; Rapp, D.; Salmon, J.T.; Waltjen, K.

    1992-06-29

    We describe a feasibility experiment to demonstrate high-order adaptive optics using a sodium-layer laser guide star. We use the copper-vapor-pumped dye lasers developed for LLNL`s atomic Vapor Laser Isotope Separation program to create the laser guide star. Closed-loop adaptive corrections will be accomplished using a 69-subaperture adaptive optics system on a one-meter telescope at LLNL. The laser bream is projected upwards from a beam director approximately 5 meters away from the main telescope, and is expected to form a spot 1-2 meters in diameter at the atmospheric sodium layer (95 km altitude). We describe the overall system architecture and adaptive optics components, and analyze the expected performance. Our long-term goal is to develop sodium-layer laser guide stars and adaptive optics for large astronomical telescopes. We discuss preliminary design trade-offs for the Keck Telescope at Mauna Kea.

  7. Development of laser guide stars and adaptive optics for large astronomical telescopes

    SciTech Connect

    Max, C.E.; Avicola, K.; Bissinger, H.; Brase, J.M.; Gavel, D.T.; Friedman, H.; Morris, J.R.; Olivier, S.S.; Rapp, D.; Salmon, J.T.; Waltjen, K.

    1992-06-29

    We describe a feasibility experiment to demonstrate high-order adaptive optics using a sodium-layer laser guide star. We use the copper-vapor-pumped dye lasers developed for LLNL's atomic Vapor Laser Isotope Separation program to create the laser guide star. Closed-loop adaptive corrections will be accomplished using a 69-subaperture adaptive optics system on a one-meter telescope at LLNL. The laser bream is projected upwards from a beam director approximately 5 meters away from the main telescope, and is expected to form a spot 1-2 meters in diameter at the atmospheric sodium layer (95 km altitude). We describe the overall system architecture and adaptive optics components, and analyze the expected performance. Our long-term goal is to develop sodium-layer laser guide stars and adaptive optics for large astronomical telescopes. We discuss preliminary design trade-offs for the Keck Telescope at Mauna Kea.

  8. Coherence gated wavefront sensorless adaptive optics for two photon excited fluorescence retinal imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jian, Yifan; Cua, Michelle; Bonora, Stefano; Pugh, Edward N.; Zawadzki, Robert J.; Sarunic, Marinko V.

    2016-03-01

    We present a novel system for adaptive optics two photon imaging. We utilize the bandwidth of the femtosecond excitation beam to perform coherence gated imaging (OCT) of the sample. The location of the focus is directly observable in the cross sectional OCT images, and adjusted to the desired depth plane. Next, using real time volumetric OCT, we perform Wavefront Sensorless Adaptive Optics (WSAO) aberration correction using a multi-element adaptive lens capable of correcting up to 4th order Zernike polynomials. The aberration correction is performed based on an image quality metric, for example intensity. The optimization time is limited only by the OCT acquisition rate, and takes ~30s. Following aberration correction, two photon fluorescence images are acquired, and compared to results without adaptive optics correction. This technique is promising for multiphoton imaging in multi-layered, scattering samples such as eye and brain, in which traditional wavefront sensing and guide-star sensorless adaptive optics approaches may not be suitable.

  9. Technology review of flight crucial flight control systems (application of optical technology)

    NASA Technical Reports Server (NTRS)

    Rediess, H. A.; Buckley, E. C.

    1984-01-01

    The survey covers the various optical elements that are considered in a fly-by-light flight control system including optical sensors and transducers, optical data links, so-called optical actuators, and optical/electro-optical processing. It also addresses airframe installation, maintenance, and repair issues. Rather than an in-depth treatment of optical technology, the survey concentrates on technology readiness and the potential advantages/disadvantages of applying the technology. The information was assembled from open literature, personal interviews, and responses to a questionnaire distributed specifically for this survey. Not all of the information obtained was consistent, particularly with respect to technology readiness. The synthesis of information into the perception of the state-of-technology is presented.

  10. The optical design of a visible adaptive optics system for the Magellan Telescope

    NASA Astrophysics Data System (ADS)

    Kopon, Derek

    The Magellan Adaptive Optics system will achieve first light in November of 2012. This AO system contains several subsystems including the 585-actuator concave adaptive secondary mirror, the Calibration Return Optic (CRO) alignment and calibration system, the CLIO 1-5 microm IR science camera, the movable guider camera and active optics assembly, and the W-Unit, which contains both the Pyramid Wavefront Sensor (PWFS) and the VisAO visible science camera. In this dissertation, we present details of the design, fabrication, assembly, alignment, and laboratory performance of the VisAO camera and its optical components. Many of these components required a custom design, such as the Spectral Differential Imaging Wollaston prisms and filters and the coronagraphic spots. One component, the Atmospheric Dispersion Corrector (ADC), required a unique triplet design that had until now never been fabricated and tested on sky. We present the design, laboratory, and on-sky results for our triplet ADC. We also present details of the CRO test setup and alignment. Because Magellan is a Gregorian telescope, the ASM is a concave ellipsoidal mirror. By simulating a star with a white light point source at the far conjugate, we can create a double-pass test of the whole system without the need for a real on-sky star. This allows us to test the AO system closed loop in the Arcetri test tower at its nominal design focal length and optical conjugates. The CRO test will also allow us to calibrate and verify the system off-sky at the Magellan telescope during commissioning and periodically thereafter. We present a design for a possible future upgrade path for a new visible Integral Field Spectrograph. By integrating a fiber array bundle at the VisAO focal plane, we can send light to a pre-existing facility spectrograph, such as LDSS3, which will allow 20 mas spatial sampling and R˜1,800 spectra over the band 0.6-1.05 microm. This would be the highest spatial resolution IFU to date, either

  11. SPARTA: the ESO standard platform for adaptive optics real time applications

    NASA Astrophysics Data System (ADS)

    Fedrigo, Enrico; Donaldson, Robert; Soenke, Christian; Myers, Richard; Goodsell, Stephen; Geng, Deli; Saunter, Chris; Dipper, Nigel

    2006-06-01

    ESO is starting a number of new projects collectively called Second Generation VLT instrumentation. Several of them will use Adaptive Optics (AO). In comparison with today's ESO AO systems, the 2nd Generation VLT AO systems will be much bigger (in terms of degrees of freedom) and faster (in terms of loop frequency). Consequently the Real-Time Computer controlling these AO systems will be significantly bigger and more challenging to build compared with today's AO systems in operation. To support the new requirements ESO started the development of a common flexible platform called SPARTA for Standard Platform for Adaptive optics Real Time Applications. The guidelines along which SPARTA is developed recognize the importance of industry standards over custom development to lower the development costs, ease the maintenance and make the system upgradeable thus delivering the performance required. SPARTA is based on a hybrid architecture that comprises all the major computing architectures available today: the high computational throughput is achieved through the combination of FPGA and DSP usage, where DSP are used as fast coprocessors and FPGA are used as front and as communication infrastructure, thus guaranteeing also the low latency. The flexibility is spread between the usage of both high-end CPUs and again the DSPs. All three technologies are organized in a parallel system interconnected by fast serial fabrics based on standard protocols. External input / output interfaces are also based on industry standard protocols, thus enabling the usage of commercially available tools for development and testing.

  12. THE INNER KILOPARSEC OF Mrk 273 WITH KECK ADAPTIVE OPTICS

    SciTech Connect

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

    2013-10-01

    There is X-ray, optical, and mid-infrared imaging and spectroscopic evidence that the late-stage ultraluminous infrared galaxy merger Mrk 273 hosts a powerful active galactic nucleus (AGN). However, the exact location of the AGN and the nature of the nucleus have been difficult to determine due to dust obscuration and the limited wavelength coverage of available high-resolution data. Here we present near-infrared integral-field spectra and images of the nuclear region of Mrk 273 taken with OSIRIS and NIRC2 on the Keck II Telescope with laser guide star adaptive optics. We observe three spatially resolved components, and analyze the nuclear molecular and ionized gas emission lines and their kinematics. We confirm the presence of the hard X-ray AGN in the southwest nucleus. In the north nucleus, we find a strongly rotating gas disk whose kinematics indicate a central black hole of mass 1.04 ± 0.1 × 10{sup 9} M{sub ☉}. The H{sub 2} emission line shows an increase in velocity dispersion along the minor axis in both directions, and an increased flux with negative velocities in the southeast direction; this provides direct evidence for a collimated molecular outflow along the axis of rotation of the disk. The third spatially distinct component appears to the southeast, 640 and 750 pc from the north and southwest nuclei, respectively. This component is faint in continuum emission but shows several strong emission line features, including [Si VI] 1.964 μm which traces an extended coronal-line region. The geometry of the [Si VI] emission combined with shock models and energy arguments suggest that [Si VI] in the southeast component must be at least partly ionized by the SW AGN or a putative AGN in the northern disk, either through photoionization or through shock-heating from strong AGN- and circumnuclear-starburst-driven outflows. This lends support to a scenario in which Mrk 273 may be a dual AGN system.

  13. The research on thermal adaptability reinforcement technology for photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Su, Nana; Zhou, Guozhong

    2015-10-01

    Nowadays, Photovoltaic module contains more high-performance components in smaller space. It is also demanded to work in severe temperature condition for special use, such as aerospace. As temperature rises, the failure rate will increase exponentially which makes reliability significantly reduce. In order to improve thermal adaptability of photovoltaic module, this paper makes a research on reinforcement technologies. Thermoelectric cooler is widely used in aerospace which has harsh working environment. So, theoretical formulas for computing refrigerating efficiency, refrigerating capacity and temperature difference are described in detail. The optimum operating current of three classical working condition is obtained which can be used to guide the design of driven circuit. Taken some equipment enclosure for example, we use thermoelectric cooler to reinforce its thermal adaptability. By building physical model and thermal model with the aid of physical dimension and constraint condition, the model is simulated by Flotherm. The temperature field cloud is shown to verify the effectiveness of reinforcement.

  14. Edge Detection to Isolate Motion in Adaptive Optics Systems

    SciTech Connect

    Chan, C W

    2003-07-11

    Adaptive optics uses signal processing techniques and deformable mirrors to minimize image degradation caused by phase aberrations. In the case of telescope imaging, the atmosphere causes phase aberrations. In the case of satellite imaging, errors due to the ultra-light-weight characteristics of the primary mirror cause phase aberrations. Scene-based Shack-Hartmann Wave Front Sensing takes the correlation between successive wavelets to determine these phase aberrations. A large problem with the scene-based approach is that motion, such as a moving car, can cause the correlation of two lenslets to peak, not where the scenes align, but where the moving object in each frame aligns. As such, the continued use of scene-based Wave Front Sensing necessitates successful isolation of moving objects from a stationary background scene. With the knowledge of which pixels are immobile, one should avoid the problem of locking onto a moving object when taking the correlation of two successive frames in time. Two main requirements of isolation are consistency and efficiency. In this document I will discuss the different edge detection algorithms explored for moving object isolation and how I came to the conclusion that, for our purposes of scene-based Shack-Hartmann WFS, edge detection is too inconsistent to be of any use. Because the Shack-Hartmann lenslets limits us to low resolutions, edge detection that works on higher resolution images will not work on our images. The results of each algorithm will show that with so few pixels per subaperature, edge detection is a poor method of identifying moving objects.

  15. Photoevaporating stellar envelopes observed with Rayleigh beacon adaptive optics

    NASA Technical Reports Server (NTRS)

    Mccullough, P. R.; Fugate, R. Q.; Christou, J. C.; Ellerbroek, B. L.; Higgins, C. H.; Spinhirne, J. M.; Cleis, R. A.; Moroney, J. F.

    1995-01-01

    We present H-alpha and I-band images of a approximately 1 min diameter field centered on theta(sup 1) C Ori made with a unique adaptive optics system that uses either starlight or Rayleigh-backscattered laser light to correct for atmospheric wavefront distortion. Approximately one-half of the stars in this region are positionally associated with knots of ionized gas, which are interpreted as photoevaporating envelopes of low-mass stars. The acronyms 'partially ionized globule' (PIGs), external ionized (accretion) disks in the environs of radiation sources (EIDERs), or protoplanetary disks (ProPlyDs) all refer to these same knots. The H-alpha fluxes of the PIGs are proportional to their 2 cm radio continumm flux densities, and for nearly all the ionized knots, the 2 cm brightness temperatures are consistent with theta(sup 1) C Ori as the primary source of ionization. The comet-like morphology of the bright nebulosities is modeled as the result of an equilibrium between photoionization, recombination, and shadowing. The radii of the ionized 'head' of the cometary PIGs grow with distance from theta(sup 1) C Ori; the radii range from approximately less than or equal to 0.05 sec to approximately 0.25 sec. We interpret the size-distance relationship as evidence that the envelopes all have the same density profile and mass-loss rate within a factor of 2. Faint, arcuate wisps are observed 1 sec to 2 sec distance from some of the cometary nebulosities; these are modeled as bow shocks caused by the wind from theta(sup 1) C Ori. The positions of the stars associated with the PIGs in the observational H-R diagram indicate they are pre-main-sequence stars with masses less than approximately 3 solar mass, with approximately 1 solar mass being typical. Their medium I-K color is 2.9.

  16. Optical Sensor Technology Development and Deployment

    SciTech Connect

    B. G. Parker

    2005-01-24

    The objectives of this ESP (Enhanced Surveillance) project are to evaluate sensor performance for future aging studies of materials, components and weapon systems. The goal of this project is to provide analysis capability to experimentally identify and characterize the aging mechanisms and kinetics of Core Stack Assembly (CSA) materials. The work on fiber optic light sources, hermetic sealing of fiber optics, fiber optic hydrogen sensors, and detection systems will be discussed.

  17. Wireless visible light communication technology using optical beamforming

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Man; Kim, Seong-Min

    2013-10-01

    We propose and demonstrate a new wireless visible light communication (VLC) technology using optical beamforming to improve signal-to-noise ratio (SNR) and transmission distance. Optical beamforming is a technology that can focus light-emitting diode (LED) light on a desired target device. Our experimental results show that SNR can be improved by 12 dB and transmission distance can be almost doubled by using optical beamforming. We can also control the modulation depth of the optical beamforming if we want to use the LED light as illumination at the same time. We also propose an algorithm to direct the beam to the target device automatically.

  18. Alternative high-resolution lithographic technologies for optical applications

    NASA Astrophysics Data System (ADS)

    Zeitner, Uwe D.; Weichelt, Tina; Bourgin, Yannick; Kinder, Robert

    2016-03-01

    Modern optical applications have special demands on the lithographic fabrication technologies. This relates to the lateral shape of the structures as well as to their three dimensional surface profile. On the other hand optical nano-structures are often periodic which allows for the use of dedicated lithographic exposure principles. The paper briefly reviews actual developments in the field of optical nano-structure generation. Special emphasis will be given to two technologies: electron-beam lithography based on a flexible cell-projection method and the actual developments in diffractive mask aligner lithography. Both offer a cost effective fabrication alternative for high resolution structures or three-dimensional optical surface profiles.

  19. Optical Parametric Technology for Methane Measurements

    NASA Technical Reports Server (NTRS)

    Dawsey, Martha; Numata, Kenji; Wu, Stewart; Riris, Haris

    2015-01-01

    Atmospheric methane (CH4) is the second most important anthropogenic greenhouse gas, with approximately 25 times the radiative forcing of carbon dioxide (CO2) per molecule. Yet, lack of understanding of the processes that control CH4 sources and sinks and its potential release from stored carbon reservoirs contributes significant uncertainty to our knowledge of the interaction between carbon cycle and climate change. At Goddard Space Flight Center (GSFC) we have been developing the technology needed to remotely measure CH4 from orbit. Our concept for a CH4 lidar is a nadir viewing instrument that uses the strong laser echoes from the Earth's surface to measure CH4. The instrument uses a tunable, narrow-frequency light source and photon-sensitive detector to make continuous measurements from orbit, in sunlight and darkness, at all latitudes and can be relatively immune to errors introduced by scattering from clouds and aerosols. Our measurement technique uses Integrated Path Differential Absorption (IPDA), which measures the absorption of laser pulses by a trace gas when tuned to a wavelength coincident with an absorption line. We have already demonstrated ground-based and airborne CH4 detection using Optical Parametric Amplifiers (OPA) at 1651 nm using a laser with approximately 10 microJ/pulse at 5kHz with a narrow linewidth. Next, we will upgrade our OPO system to add several more wavelengths in preparation for our September 2015 airborne campaign, and expect that these upgrades will enable CH4 measurements with 1% precision (10-20 ppb).

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  1. Rural Communities and Optical Information Technologies: Optical Disks Move Rural America Closer to the Information Mainstream.

    ERIC Educational Resources Information Center

    Remington, David Gray

    Optical disk technologies now offer a way to move large, complex, remote computer databases from the large urban areas to rural users. Recently, the Optical Information Systems (OIS) Conference provided an opportunity to discuss the use of this new technology for a variety of innovative applications; for example, "The State Education…

  2. Adaptive Optics for Satellite Imaging and Space Debris Ranging

    NASA Astrophysics Data System (ADS)

    Bennet, F.; D'Orgeville, C.; Price, I.; Rigaut, F.; Ritchie, I.; Smith, C.

    Earth's space environment is becoming crowded and at risk of a Kessler syndrome, and will require careful management for the future. Modern low noise high speed detectors allow for wavefront sensing and adaptive optics (AO) in extreme circumstances such as imaging small orbiting bodies in Low Earth Orbit (LEO). The Research School of Astronomy and Astrophysics (RSAA) at the Australian National University have been developing AO systems for telescopes between 1 and 2.5m diameter to image and range orbiting satellites and space debris. Strehl ratios in excess of 30% can be achieved for targets in LEO with an AO loop running at 2kHz, allowing the resolution of small features (<30cm) and the capability to determine object shape and spin characteristics. The AO system developed at RSAA consists of a high speed EMCCD Shack-Hartmann wavefront sensor, a deformable mirror (DM), and realtime computer (RTC), and an imaging camera. The system works best as a laser guide star system but will also function as a natural guide star AO system, with the target itself being the guide star. In both circumstances tip-tilt is provided by the target on the imaging camera. The fast tip-tilt modes are not corrected optically, and are instead removed by taking images at a moderate speed (>30Hz) and using a shift and add algorithm. This algorithm can also incorporate lucky imaging to further improve the final image quality. A similar AO system for space debris ranging is also in development in collaboration with Electro Optic Systems (EOS) and the Space Environment Management Cooperative Research Centre (SERC), at the Mount Stromlo Observatory in Canberra, Australia. The system is designed for an AO corrected upward propagated 1064nm pulsed laser beam, from which time of flight information is used to precisely range the target. A 1.8m telescope is used for both propagation and collection of laser light. A laser guide star, Shack-Hartmann wavefront sensor, and DM are used for high order

  3. 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.

  4. Polyguide polymeric technology for optical interconnect circuits and components

    NASA Astrophysics Data System (ADS)

    Booth, Bruce L.; Marchegiano, Joseph E.; Chang, Catherine T.; Furmanak, Robert J.; Graham, Douglas M.; Wagner, Richard G.

    1997-04-01

    The expanding information revolution has been made possible by the development of optical communication technology. To meet the escalating demand for information transmitted and processed at high data rates and the need to circumvent the growing electronic circuit bottlenecks, mass deployment of not only optical fiber networks but manufacturable optical interconnect circuits, components and connectors for interfacing fibers and electronics that meet economic and performance constraints are absolutely necessary. Polymeric waveguide optical interconnection are considered increasingly important to meet these market needs. DuPont's polyguide polymeric integrated optic channel waveguide system is thought by many to have considerable potential for a broad range of passive optical interconnect applications. In this paper the recent advances, status, and unique attributes of the technology are reviewed. Product and technology developments currently in progress including parallel optical ink organization and polymer optical interconnect technology developments funded by DARPA are used as examples to describe polyguide breadth and potential for manufacture and deployment of optical interconnection products for single and multimode telecom and datacom waveguide applications.

  5. Development of optical fiber technology in Poland: 2014

    NASA Astrophysics Data System (ADS)

    Dorosz, Jan; Romaniuk, Ryszard S.

    2014-05-01

    In this paper, the authors, chairs of the 15th Conference on Optical Fibers and Their Applications OFTA2014, and editors of the conference proceedings summarize the developments of optical fiber technology in Poland (during the period of 2012-2014) on the basis of papers presented there and consecutively published in this volume. The digest covers the periodically presented work results every 18 months during the meetings on optical fibers in Białystok - Lipowy Most (with emphasis on technology and applications) and Lublin - Nałęczow (with emphasis on materials and technologies). The XVth Conference on Optical Fibers and Their Applications was held in Białystok and Lipowy Most on 29.01-01.02.2014. The first conference from this cycle was organized in Jabłonna in 1976. Conference topics were: optical fiber technology, materials for optoelectronics and photonics, rare earth doped and luminescent materials, metrology of optical fibers, components and optoelectronic circuits, applications of optical fibers, waveguides and optical fiber sensors, and lighting technology. The conference was attended by 120 participants, including international guests, and 90 papers were presented. Conference papers are traditionally published in Proceedings SPIE.

  6. Design and progress toward a multi-conjugate adaptive optics system for distributed aberration correction

    SciTech Connect

    Baker, K; Olivier, S; Tucker, J; Silva, D; Gavel, D; Lim, R; Gratrix, E

    2004-08-17

    This article investigates the use of a multi-conjugate adaptive optics system to improve the field-of-view for the system. The emphasis of this research is to develop techniques to improve the performance of optical systems with applications to horizontal imaging. The design and wave optics simulations of the proposed system are given. Preliminary results from the multi-conjugate adaptive optics system are also presented. The experimental system utilizes a liquid-crystal spatial light modulator and an interferometric wave-front sensor for correction and sensing of the phase aberrations, respectively.

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

    NASA Astrophysics Data System (ADS)

    Alliss, R.

    2014-09-01

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

  8. Multipoint dynamically reconfigure adaptive distributed fiber optic acoustic emission sensor (FAESense) system for condition based maintenance

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar; Prohaska, John; Kempen, Connie; Esterkin, Yan; Sun, Sunjian; Krishnaswamy, Sridhar

    2010-09-01

    This paper describes preliminary results obtained under a Navy SBIR contract by Redondo Optics Inc. (ROI), in collaboration with Northwestern University towards the development and demonstration of a next generation, stand-alone and fully integrated, dynamically reconfigurable, adaptive fiber optic acoustic emission sensor (FAESense™) system for the in-situ unattended detection and localization of shock events, impact damage, cracks, voids, and delaminations in new and aging critical infrastructures found in ships, submarines, aircraft, and in next generation weapon systems. ROI's FAESense™ system is based on the integration of proven state-of-the-art technologies: 1) distributed array of in-line fiber Bragg gratings (FBGs) sensors sensitive to strain, vibration, and acoustic emissions, 2) adaptive spectral demodulation of FBG sensor dynamic signals using two-wave mixing interferometry on photorefractive semiconductors, and 3) integration of all the sensor system passive and active optoelectronic components within a 0.5-cm x 1-cm photonic integrated circuit microchip. The adaptive TWM demodulation methodology allows the measurement of dynamic high frequnency acoustic emission events, while compensating for passive quasi-static strain and temperature drifts. It features a compact, low power, environmentally robust 1-inch x 1-inch x 4-inch small form factor (SFF) package with no moving parts. The FAESense™ interrogation system is microprocessor-controlled using high data rate signal processing electronics for the FBG sensors calibration, temperature compensation and the detection and analysis of acoustic emission signals. Its miniaturized package, low power operation, state-of-the-art data communications, and low cost makes it a very attractive solution for a large number of applications in naval and maritime industries, aerospace, civil structures, the oil and chemical industry, and for homeland security applications.

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  10. A FOSSIL BULGE GLOBULAR CLUSTER REVEALED BY VERY LARGE TELESCOPE MULTI-CONJUGATE ADAPTIVE OPTICS

    SciTech Connect

    Ortolani, Sergio; Barbuy, Beatriz; Momany, Yazan; Saviane, Ivo; Jilkova, Lucie; Bica, Eduardo; Salerno, Gustavo M.; Jungwiert, Bruno E-mail: barbuy@astro.iag.usp.br E-mail: isaviane@eso.org E-mail: bica@if.ufrgs.br

    2011-08-10

    The globular cluster HP 1 is projected on the bulge, very close to the Galactic center. The Multi-Conjugate Adaptive Optics Demonstrator on the Very Large Telescope allowed us to acquire high-resolution deep images that, combined with first epoch New Technology Telescope data, enabled us to derive accurate proper motions. The cluster and bulge fields' stellar contents were disentangled through this process and produced an unprecedented definition in color-magnitude diagrams of this cluster. The metallicity of [Fe/H] {approx} -1.0 from previous spectroscopic analysis is confirmed, which together with an extended blue horizontal branch imply an age older than the halo average. Orbit reconstruction results suggest that HP 1 is spatially confined within the bulge.

  11. Ultrafast all-optical technologies for bidirectional optical wireless communications.

    PubMed

    Jin, Xian; Hristovski, Blago A; Collier, Christopher M; Geoffroy-Gagnon, Simon; Born, Brandon; Holzman, Jonathan F

    2015-04-01

    In this Letter, a spherical retro-modulator architecture is introduced for operation as a bidirectional transceiver in passive optical wireless communication links. The architecture uses spherical retroreflection to enable retroreflection with broad directionality (2π steradians), and it uses all-optical beam interaction to enable modulation on ultrafast timescales (120 fs duration). The spherical retro-modulator is investigated from a theoretical standpoint and is fabricated for testing with three glasses, N-BK7, N-LASF9, and S-LAH79. It is found that the S-LAH79 structure provides the optimal refraction and nonlinearity for the desired retroreflection and modulation capabilities.

  12. Surveying and optical tooling technologies combined to align a skewed beamline at the LAMPF accelerator

    SciTech Connect

    Bauke, W.; Clark, D.A.; Trujillo, P.B.

    1985-01-01

    Optical Tooling evolved from traditional surveying, and both technologies are sometimes used interchangeably in large industrial installations, since the instruments and their specialized adapters and supports complement each other well. A unique marriage of both technologies was accomplished in a novel application at LAMPF, the Los Alamos Meson Physics Facility. LAMPF consists of a linear accelerator with multiple target systems, one of which had to be altered to accommodate a new beamline for a neutrino experiment. The new line was to be installed into a crowded beam tunnel and had to be skewed and tilted in compound angles to avoid existing equipment. In this paper we describe how Optical Tooling was used in conjunction with simple alignment and reference fixtures to set fiducials on the magnets and other mechanical components of the beamline, and how theodolites and sight levels were then adapted to align these components along the calculated skew planes. Design tolerances are compared with measured alignment results.

  13. Progress on developing wavefront sensorless adaptive optics optical coherence tomography for in vivo retinal imaging in mice

    NASA Astrophysics Data System (ADS)

    Zam, Azhar; Zhang, Pengfei; Jian, Yifan; Sarunic, Marinko V.; Bonora, Stefano; Pugh, Edward N.; Zawadzki, Robert J.

    2015-03-01

    We present a new design for a wavefront sensorless adaptive optics (WS-AO) Fourier domain optical coherence tomography (FD-OCT) system for small animal retinal imaging in vivo. Without the optical complications necessary for inclusion of a wavefront sensor in the optical system, this version of WS-AO FD-OCT system has a simplified optical design, including elimination of long focal length scanning optics and optical conjugation of vertical and horizontal scanners. This modification provides a modular large Field of View for retinal screening (25 degree visual angle), while also allowing a "zoom" capability for allocating all the scanning resources to a smaller region of interest, allowing high resolution aberration-corrected imaging. In the present system we used a 0 Dpt contact lens to stabilize the mouse eye position and to allow long duration imaging. Defocus (axial focus position) in our system is controlled by the collimation of the OCT sample arm entrance beam.

  14. The Adaptive Aerosol Delivery (AAD) technology: Past, present, and future.

    PubMed

    Denyer, John; Dyche, Tony

    2010-04-01

    Conventional aerosol delivery systems and the availability of new technologies have led to the development of "intelligent" nebulizers such as the I-neb Adaptive Aerosol Delivery (AAD) System. Based on the AAD technology, the I-neb AAD System has been designed to continuously adapt to changes in the patient's breathing pattern, and to pulse aerosol only during the inspiratory part of the breathing cycle. This eliminates waste of aerosol during exhalation, and creates a foundation for precise aerosol (dose) delivery. To facilitate the delivery of precise metered doses of aerosol to the patient, a unique metering chamber design has been developed. Through the vibrating mesh technology, the metering chamber design, and the AAD Disc function, the aerosol output rate and metered (delivered) dose can be tailored to the demands of the specific drug to be delivered. In the I-neb AAD System, aerosol delivery is guided through two algorithms, one for the Tidal Breathing Mode (TBM), and one for slow and deep inhalations, the Target Inhalation Mode (TIM). The aim of TIM is to reduce the treatment time by increasing the total inhalation time per minute, and to increase lung deposition by reducing impaction in the upper airways through slow and deep inhalations. A key feature of the AAD technology is the patient feedback mechanisms that are provided to guide the patient on delivery performance. These feedback signals, which include visual, audible, and tactile forms, are configured in a feedback cascade that leads to a high level of compliance with the use of the I-neb AAD System. The I-neb Insight and the Patient Logging System facilitate a further degree of sophistication to the feedback mechanisms, by providing information on long term adherence and compliance data. These can be assessed by patients and clinicians via a Web-based delivery of information in the form of customized graphical analyses.

  15. The Adaptive Aerosol Delivery (AAD) Technology: Past, Present, and Future

    PubMed Central

    Dyche, Tony

    2010-01-01

    Abstract Conventional aerosol delivery systems and the availability of new technologies have led to the development of “intelligent” nebulizers such as the I-neb Adaptive Aerosol Delivery (AAD) System. Based on the AAD technology, the I-neb AAD System has been designed to continuously adapt to changes in the patient's breathing pattern, and to pulse aerosol only during the inspiratory part of the breathing cycle. This eliminates waste of aerosol during exhalation, and creates a foundation for precise aerosol (dose) delivery. To facilitate the delivery of precise metered doses of aerosol to the patient, a unique metering chamber design has been developed. Through the vibrating mesh technology, the metering chamber design, and the AAD Disc function, the aerosol output rate and metered (delivered) dose can be tailored to the demands of the specific drug to be delivered. In the I-neb AAD System, aerosol delivery is guided through two algorithms, one for the Tidal Breathing Mode (TBM), and one for slow and deep inhalations, the Target Inhalation Mode (TIM). The aim of TIM is to reduce the treatment time by increasing the total inhalation time per minute, and to increase lung deposition by reducing impaction in the upper airways through slow and deep inhalations. A key feature of the AAD technology is the patient feedback mechanisms that are provided to guide the patient on delivery performance. These feedback signals, which include visual, audible, and tactile forms, are configured in a feedback cascade that leads to a high level of compliance with the use of the I-neb AAD System. The I-neb Insight and the Patient Logging System facilitate a further degree of sophistication to the feedback mechanisms, by providing information on long term adherence and compliance data. These can be assessed by patients and clinicians via a Web-based delivery of information in the form of customized graphical analyses. PMID:20373904

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

    NASA Astrophysics Data System (ADS)

    Moniem, T. A.

    2016-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Foor, Wesley E.; Neifeld, Mark A.

    1994-06-01

    An adaptive optical radial basis function classifier for handwritten digit recognition is experimentally demonstrated. We describe a spatially- multiplexed system incorporating on-line adaptation of weights and basis function widths to provide robustness to optical system imperfections and system noise. The optical system computes the Euclidean distances between a 100-dimensional input and 198 stored reference patterns in parallel using dual vector-matrix multipliers. For this experimental software is used to perform the on-line learning of the weights and basis function widths. An experimental recognition rate of 86.7% correct out of 300 testing samples is achieved with the adaptive training versus 52.3% correct for non-adaptive training. The experimental results from the optical system are compared with data from a computer model of the system in order to identify noise sources and indicate possible improvements for system performance.

  18. Monte Carlo modelling of multiconjugate adaptive optics performance on the European Extremely Large Telescope

    NASA Astrophysics Data System (ADS)

    Basden, A. G.

    2015-11-01

    The performance of a wide-field adaptive optics system depends on input design parameters. Here we investigate the performance of a multiconjugate adaptive optics system design for the European Extremely Large Telescope, using an end-to-end Monte Carlo adaptive optics simulation tool, DASP (Durham adaptive optics simulation platform). We consider parameters such as the number of laser guide stars, sodium layer depth, wavefront sensor pixel scale, number of deformable mirrors (DMs), mirror conjugation and actuator pitch. We provide potential areas where costs savings can be made, and investigate trade-offs between performance and cost. We conclude that a six-laser guide star system using three DMs seems to be a sweet spot for performance and cost compromise.

  19. 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.

  20. Adaptive optics-assisted optical coherence tomography for imaging of patients with age related macular degeneration

    NASA Astrophysics Data System (ADS)

    Sudo, Kenta; Cense, Barry

    2013-03-01

    We developed an optical coherence tomography (OCT) prototype with a sample arm that uses a 3.4 mm beam, which is considerably larger than the 1.2 to 1.5 mm beam that is used in commercialized OCT systems. The system is equipped with adaptive optics (AO), and to distinguish it from traditional AO-OCT systems with a larger 6 mm beam we have coined this concept AO-assisted OCT. Compared to commercialized OCT systems, the 3.4 mm aperture combined with AO improves light collection efficiency and imaging lateral resolution. In this paper, the performance of the AOa-OCT system was compared to a standard OCT system and demonstrated for imaging of age-related macular degeneration (AMD). Measurements were performed on the retinas of three human volunteers with healthy eyes and on one eye of a patient diagnosed with AMD. The AO-assisted OCT system imaged retinal structures of healthy human eyes and a patient eye affected by AMD with higher lateral resolution and a 9° by 9° field of view. This combination of a large isoplanatic patch and high lateral resolution can be expected to fill a gap between standard OCT with a 1.2 mm beam and conventional AO-OCT with a 6 mm beam and a 1.5° by 1.5° isoplanatic patch.

  1. High resolution mesospheric sodium properties for adaptive optics applications

    NASA Astrophysics Data System (ADS)

    Pfrommer, T.; Hickson, P.

    2014-05-01

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

  2. Adapting Technological Interventions to Meet the Needs of Priority Populations.

    PubMed

    Linke, Sarah E; Larsen, Britta A; Marquez, Becky; Mendoza-Vasconez, Andrea; Marcus, Bess H

    2016-01-01

    Cardiovascular diseases (CVD) comprise the leading cause of mortality worldwide, accounting for 3 in 10 deaths. Individuals with certain risk factors, including tobacco use, obesity, low levels of physical activity, type 2 diabetes mellitus, racial/ethnic minority status and low socioeconomic status, experience higher rates of CVD and are, therefore, considered priority populations. Technological devices such as computers and smartphones are now routinely utilized in research studies aiming to prevent CVD and its risk factors, and they are also rampant in the public and private health sectors. Traditional health behavior interventions targeting these risk factors have been adapted for technology-based approaches. This review provides an overview of technology-based interventions conducted in these priority populations as well as the challenges and gaps to be addressed in future research. Researchers currently possess tremendous opportunities to engage in technology-based implementation and dissemination science to help spread evidence-based programs focusing on CVD risk factors in these and other priority populations. PMID:26957186

  3. Electro-Optical Laser Technology. Curriculum Utilization. Final Report.

    ERIC Educational Resources Information Center

    Nawn, John H.

    This report describes a program to prepare students for employment as laser technicians and laser operators and to ensure that they have the necessary skills required by the industry. The objectives are to prepare a curriculum and syllabus for an associate degree program in Electro-Optical Laser Technology. The 2-year Electro-Optical Laser program…

  4. Ultra-stable optical amplifier technologies for dynamic optical switching networks

    NASA Astrophysics Data System (ADS)

    Shiraiwa, M.; Tsang, K. S.; Man, R.; Puttnam, B. J.; Awaji, Y.; Wada, N.

    2015-01-01

    High-capacity fiber-optic communications are promising technologies to satisfy people's continuously growing demands for bandwidth hungry data services. Multi-wavelength optical circuit switching (OCS) technology is already widely deployed, however, with the limited number of transceivers equipped at each optical node and other constraints, the number of lightpaths which can be established and employed simultaneously in an optical network is restricted. This reduces the utilization efficiency of wavelength resources. Comparing to OCS, dynamic optical switching systems such as optical packet switching (OPS) offer higher efficiency in terms of wavelength resource utilization and have the potential to share more of the wavelength resources on fiber-links between larger numbers of users simultaneously. In such networks, bursty input signals or changes in traffic density may cause optical power surges that can damage optical components or impose gain transients on the signals that impair signal quality. A common approach for reducing gain transients is to employ electrical automatic gain control (AGC) or optical gain-clamping by optical feedback (OFB). AGC may be limited by the speed of the feedback circuit and result in additional transients. Meanwhile OFB can clamp the gain of power varying optical signals without transient but can introduce amplitude fluctuations caused by relaxation oscillations in the lasing cavity for large input power fluctuations. We propose and demonstrate a novel scheme for suppressing the power transients and the relaxation oscillations. This scheme can be utilized in optical amplifiers even if the optical feedback is employed.

  5. Planning for optical disk technology with digital cartography.

    USGS Publications Warehouse

    Light, D.L.

    1986-01-01

    A major shortfall that still exists in digital systems is the need for very large mass storage capacity. The decade of the 1980s has introduced laser optical disk storage technology, which may be the breakthrough needed for mass storage. This paper addresses system concepts for digital cartography during the transition period. Emphasis will be placed on determining USGS mass storage requirements and introducing laser optical disk technology for handling storage problems for digital data in this decade.-from Author

  6. Adaptive Nulling: A New Enabling Technology for Interferometric Exoplanet

    NASA Technical Reports Server (NTRS)

    Lay, Oliver P.; Jeganathan, Muthu; Peters, Robert

    2003-01-01

    Deep, stable nulling of starlight requires careful control of the amplitudes and phases of the beams that are being combined. The detection of earth-like planets using the interferometer architectures currently being considered for the Terrestrial Planet Finder mission require that the E-field amplitudes are balanced at the level of approx. 0.1%, and the phases are controlled at the level of 1 mrad (corresponding to approx.1.5 nm for a wavelength of 10 microns). These conditions must be met simultaneously at all wavelengths across the science band, and for both polarization states, imposing unrealistic tolerances on the symmetry between the optical beamtrains. We introduce the concept of a compensator that is inserted into the beamtrain, which can adaptively correct for the mismatches across the spectrum, enabling deep nulls with realistic, imperfect optics. The design presented uses a deformable mirror to adjust the amplitude and phase of each beam as an arbitrary function of wavelength and polarization. A proof-of-concept experiment will be conducted at visible/near-IR wavelengths, followed by a system operating in the Mid-IR band.

  7. IMAGING WITH MULTIMODAL ADAPTIVE-OPTICS OPTICAL COHERENCE TOMOGRAPHY IN MULTIPLE EVANESCENT WHITE DOT SYNDROME: THE STRUCTURE AND FUNCTIONAL RELATIONSHIP

    PubMed Central

    Legarreta, Andrew D.; Legarreta, John E.; Nadler, Zach; Gallagher, Denise; Hammer, Daniel X.; Ferguson, R. Daniel; Iftimia, Nicusor; Wollstein, Gadi; Schuman, Joel S.

    2016-01-01

    Purpose: To elucidate the location of pathological changes in multiple evanescent white dot syndrome (MEWDS) with the use of multimodal adaptive optics (AO) imaging. Methods: A 5-year observational case study of a 24-year-old female with recurrent MEWDS. Full examination included history, Snellen chart visual acuity, pupil assessment, intraocular pressures, slit lamp evaluation, dilated fundoscopic exam, imaging with Fourier-domain optical coherence tomography (FD-OCT), blue-light fundus autofluorescence (FAF), fundus photography, fluorescein angiography, and adaptive-optics optical coherence tomography. Results: Three distinct acute episodes of MEWDS occurred during the period of follow-up. Fourier-domain optical coherence tomography and adaptive-optics imaging showed disturbance in the photoreceptor outer segments (PR OS) in the posterior pole with each flare. The degree of disturbance at the photoreceptor level corresponded to size and extent of the visual field changes. All findings were transient with delineation of the photoreceptor recovery from the outer edges of the lesion inward. Hyperautofluorescence was seen during acute flares. Increase in choroidal thickness did occur with each active flare but resolved. Conclusion: Although changes in the choroid and RPE can be observed in MEWDS, Fourier-domain optical coherence tomography, and multimodal adaptive optics imaging localized the visually significant changes seen in this disease at the level of the photoreceptors. These transient retinal changes specifically occur at the level of the inner segment ellipsoid and OS/RPE line. En face optical coherence tomography imaging provides a detailed, yet noninvasive method for following the convalescence of MEWDS and provides insight into the structural and functional relationship of this transient inflammatory retinal disease. PMID:26735319

  8. Critical reviews of fiber-optic communication technology Optical fibers

    NASA Astrophysics Data System (ADS)

    Kapron, F. P.

    The review begins with brief highlights of the history of fiber optics, followed by a discussion of the attributes of shortwave and longwave transmission. This leads to an investigation of various fiber types, short-haul considerations, and then single-mode aspects. Specialty fiber is briefly covered, followed by a survey of several research trends today that will lead to new systems capabilities in the future. No references are given, since hundreds would be necessary to make the list even partially complete.

  9. NIF Optical Materials and Fabrication Technologies: An Overview

    SciTech Connect

    Campbell, J H; Hawley-Fedder, R; Stolz, C J; Menapace, J A; Borden, M R; Whitman, P; Yu, J; Runkel, M; Riley, M; Feit, M; Hackel, R

    2004-02-23

    The high-energy/high-power section of the NIF laser system contains 7360 meter-scale optics. Advanced optical materials and fabrication technologies needed to manufacture the NIF optics have been developed and put into production at key vendor sites. Production rates are up to 20 times faster and per-optic costs 5 times lower than could be achieved prior to the NIF. In addition, the optics manufactured for NIF are better than specification giving laser performance better than the design. A suite of custom metrology tools have been designed, built and installed at the vendor sites to verify compliance with NIF optical specifications. A brief description of the NIF optical wavefront specifications for the glass and crystal optics is presented. The wavefront specifications span a continuous range of spatial scale-lengths from 10 {micro}m to 0.5 m (full aperture). We have continued our multi-year research effort to improve the lifetime (i.e. damage resistance) of bulk optical materials, finished optical surfaces and multi-layer dielectric coatings. New methods for post-processing the completed optic to improve the damage resistance have been developed and made operational. This includes laser conditioning of coatings, glass surfaces and bulk KDP and DKDP and well as raster and full aperture defect mapping systems. Research on damage mechanisms continues to drive the development of even better optical materials.

  10. Reducing adaptive optics latency using Xeon Phi many-core processors

    NASA Astrophysics Data System (ADS)

    Barr, David; Basden, Alastair; Dipper, Nigel; Schwartz, Noah

    2015-11-01

    The next generation of Extremely Large Telescopes (ELTs) for astronomy will rely heavily on the performance of their adaptive optics (AO) systems. Real-time control is at the heart of the critical technologies that will enable telescopes to deliver the best possible science and will require a very significant extrapolation from current AO hardware existing for 4-10 m telescopes. Investigating novel real-time computing architectures and testing their eligibility against anticipated challenges is one of the main priorities of technology development for the ELTs. This paper investigates the suitability of the Intel Xeon Phi, which is a commercial off-the-shelf hardware accelerator. We focus on wavefront reconstruction performance, implementing a straightforward matrix-vector multiplication (MVM) algorithm. We present benchmarking results of the Xeon Phi on a real-time Linux platform, both as a standalone processor and integrated into an existing real-time controller (RTC). Performance of single and multiple Xeon Phis are investigated. We show that this technology has the potential of greatly reducing the mean latency and variations in execution time (jitter) of large AO systems. We present both a detailed performance analysis of the Xeon Phi for a typical E-ELT first-light instrument along with a more general approach that enables us to extend to any AO system size. We show that systematic and detailed performance analysis is an essential part of testing novel real-time control hardware to guarantee optimal science results.

  11. Using Assistive Technology Adaptations To Include Students with Learning Disabilities in Cooperative Learning Activities.

    ERIC Educational Resources Information Center

    Bryant, Diane Pedrotty; Bryant, Brian R.

    1998-01-01

    Discusses a process for integrating technology adaptations for students with learning disabilities into cooperative-learning activities in terms of three components: (1) selecting adaptations; (2) monitoring use of adaptations during cooperative-learning activities; and (3) evaluating the adaptations' effectiveness. Barriers to and support systems…

  12. Composite technology for lightweight optical mirrors

    NASA Astrophysics Data System (ADS)

    Abt, Bernd; Helwig, Gunter; Scheulen, Dietmar

    1990-07-01

    Reflectors for antennas using fiber-composite technology today represent the state of the art, and mirrors for radio telescopes occasionally are already made using this technology. For even shorter wavelengths, including the visible light, glass mirrors have been used almost exclusively and, rarely, metal mirrors (for example made of beryllium). In general a surface contour accuracy of about 1/20 wavelength is required. Years of development work based on experience gained in aircraft construction and space technology made it possible to improve fiber-composite technology to such an extent that a substitute for heavy glass has become feasible, opening up new applications for lighter and/or larger mirrors.

  13. Optical design for the Narrow Field InfraRed Adaptive Optics System (NFIRAOS) Petite on the Thirty Meter Telescope

    SciTech Connect

    Bauman, B; Gavel, D; Dekany, R; Ellerbroek, B

    2005-08-02

    We describe an exploratory optical design for the Narrow Field InfraRed Adaptive Optics (AO) System (NFIRAOS) Petite, a proposed adaptive optics system for the Thirty Meter Telescope Project. NFIRAOS will feed infrared spectrograph and wide-field imaging instruments with a diffraction limited beam. The adaptive optics system will require multi-guidestar tomographic wavefront sensing and multi-conjugate AO correction. The NFIRAOS Petite design specifications include two small 60 mm diameter deformable mirrors (DM's) used in a woofer/tweeter or multiconjugate arrangement. At least one DM would be a micro-electromechanical system (MEMS) DM. The AO system would correct a 10 to 30 arcsec diameter science field as well as laser guide stars (LGS's) located within a 60 arcsec diameter field and low-order or tip/tilt natural guide stars (NGS's) within a 60 arcsec diameter field. The WFS's are located downstream of the DM's so that they can be operated in true closed-loop, which is not necessarily a given in extremely large telescope adaptive optics design. The WFS's include adjustable corrector elements which correct the static aberrations of the AO relay due to field position and LGS distance height.

  14. Diffractive optics technology and the NASA Geostationary Earth Observatory (GEO)

    NASA Technical Reports Server (NTRS)

    Morris, G. Michael; Michaels, Robert L.; Faklis, Dean

    1992-01-01

    Diffractive (or binary) optics offers unique capabilities for the development of large-aperture, high-performance, light-weight optical systems. The Geostationary Earth Observatory (GEO) will consist of a variety of instruments to monitor the environmental conditions of the earth and its atmosphere. The aim of this investigation is to analyze the design of the GEO instrument that is being proposed and to identify the areas in which diffractive (or binary) optics technology can make a significant impact in GEO sensor design. Several potential applications where diffractive optics may indeed serve as a key technology for improving the performance and reducing the weight and cost of the GEO sensors have been identified. Applications include the use of diffractive/refractive hybrid lenses for aft-optic imagers, diffractive telescopes for narrowband imaging, subwavelength structured surfaces for anti-reflection and polarization control, and aberration compensation for reflective imaging systems and grating spectrometers.

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

    PubMed

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

    2011-11-21

    Femtosecond laser fabrication of controlled three dimensional structures deep in the bulk of diamond is facilitated by a dual adaptive optics system. A deformable mirror is used in parallel with a liquid crystal spatial light modulator to compensate the extreme aberrations caused by the refractive index mismatch between the diamond and the objective immersion medium. It is shown that aberration compensation is essential for the generation of controlled micron-scale features at depths greater than 200 μm, and the dual adaptive optics approach demonstrates increased fabrication efficiency relative to experiments using a single adaptive element. PMID:22109438

  16. Faraday-effect light-valve arrays for adaptive optical instruments

    SciTech Connect

    Hirleman, E.D.; Dellenback, P.A.

    1987-01-01

    The ability to adapt to a range of measurement conditions by autonomously configuring software or hardware on-line will be an important attribute of next-generation intelligent sensors. This paper reviews the characteristics of spatial light modulators (SLM) with an emphasis on potential integration into adaptive optical instruments. The paper focuses on one type of SLM, a magneto-optic device based on the Faraday effect. Finally, the integration of the Faraday-effect SLM into a laser-diffraction particle-sizing instrument giving it some ability to adapt to the measurement context is discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  18. Electroactive and Optically Adaptive Bionanocomposite for Reconfigurable Microlens.

    PubMed

    Sadasivuni, Kishor Kumar; Ponnamma, Deepalekshmi; Ko, Hyun-U; Zhai, Lindong; Kim, Hyun-Chan; Kim, Jaehwan

    2016-05-26

    This paper introduces an electroactive bionanocomposite based on poly(diethylene glycol adipate) (PDEGA) and cellulose nanocrystals (CNCs). The bionanocomposites were made using CNCs extracted from cotton and by optimizing its concentration in terms of the optical transmittance and viscosity. The characteristic properties of the materials were analyzed using contact angle measurements and Fourier transformation infrared spectra. Using the PDEGA/CNC bionanocomposite at a very low concentration of CNCs, a configurable lens having a robust, self-contained tunable optical structure was developed. The shape and curvature of the soft PDEGA/CNC device were controlled by applying voltage, and the focal length was measured. The simple structure, high optical transparency, biodegradability, thermal stability, high durability, and low power consumption make the new material particularly useful in fabricating a reconfigurable lens for future electronic and optical devices. PMID:27163166

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

    SciTech Connect

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

    2001-09-27

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

  20. Interpretation of Flood-Illuminated Adaptive Optics Images in Subjects with Retinitis Pigmentosa.

    PubMed

    Gale, Michael J; Feng, Shu; Titus, Hope E; Smith, Travis B; Pennesi, Mark E

    2016-01-01

    The purpose of this study was to correlate features on flood-illuminated adaptive optics (AO) images with color fundus, fundus autofluorescence (FAF) and spectral domain optical coherence tomography (SD-OCT) images in patients with retinitis pigmentosa (RP). We imaged 39 subjects diagnosed with RP using the rtx1™ flood-illuminated AO camera from Imagine Eyes (Orsay, France). We observed a correlation between hyper-autofluoresence changes on FAF, disruption of the interdigitation zone (IZ) on SD-OCT and loss of reflective cone profiles on AO. Four main patterns of cone-reflectivity were seen on AO: presumed healthy cone mosaics, hypo-reflective blurred cone-like structures, higher frequency disorganized hyper-reflective spots, and lower frequency hypo-reflective spots. These regions were correlated to progressive phases of cone photoreceptor degeneration observed using SD-OCT and FAF. These results help provide interpretation of en face images obtained by flood-illuminated AO in subjects with RP. However, significant ambiguity remains as to what truly constitutes a cone, especially in areas of degeneration. With further refinements in technology, flood illuminated AO imaging has the potential to provide rapid, standardized, longitudinal and lower cost imaging in patients with retinal degeneration.

  1. Implementation of adaptive optics in fluorescent microscopy using wavefront sensing and correction

    NASA Astrophysics Data System (ADS)

    Azucena, Oscar; Crest, Justin; Cao, Jian; Sullivan, William; Kner, Peter; Gavel, Donald; Dillon, Daren; Olivier, Scot; Kubby, Joel

    2010-02-01

    Adaptive optics (AO) improves the quality of astronomical imaging systems by using real time measurement of the turbulent medium in the optical path using a guide star (natural or artificial) as a point source reference beacon [1]. AO has also been applied to vision science to improve the view of the human eye. This paper will address our current research focused on the improvement of fluorescent microscopy for biological imaging utilizing current AO technology. A Shack-Hartmann wavefront sensor (SHWS) is used to measure the aberration introduced by a Drosophila Melanogaster embryo with an implanted 1 micron fluorescent bead that serves as a point source reference beacon. Previous measurements of the wavefront aberrations have found an average peak-to-valley and root-mean-square (RMS) wavefront error of 0.77 micrometers and 0.15 micrometers, respectively. Measurements of the Zernike coefficients indicated that the correction of the first 14 Zernike coefficients is sufficient to correct the aberrations we measured. Here we show that a MEMS deformable mirror with 3.5 microns of stroke and 140 actuators is sufficient to correct these aberrations. The design, assembly and initial results for the use of a MEMS deformable mirror, SHWS and implanted fluorescent reference beacon for wavefront correction are discussed.

  2. Optical interconnect technologies for high-bandwidth ICT systems

    NASA Astrophysics Data System (ADS)

    Chujo, Norio; Takai, Toshiaki; Mizushima, Akiko; Arimoto, Hideo; Matsuoka, Yasunobu; Yamashita, Hiroki; Matsushima, Naoki

    2016-03-01

    The bandwidth of information and communication technology (ICT) systems is increasing and is predicted to reach more than 10 Tb/s. However, an electrical interconnect cannot achieve such bandwidth because of its density limits. To solve this problem, we propose two types of high-density optical fiber wiring for backplanes and circuit boards such as interface boards and switch boards. One type uses routed ribbon fiber in a circuit board because it has the ability to be formed into complex shapes to avoid interfering with the LSI and electrical components on the board. The backplane is required to exhibit high density and flexibility, so the second type uses loose fiber. We developed a 9.6-Tb/s optical interconnect demonstration system using embedded optical modules, optical backplane, and optical connector in a network apparatus chassis. We achieved 25-Gb/s transmission between FPGAs via the optical backplane.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  4. Optical diagnosis of mammary ductal carcinoma using advanced optical technology

    NASA Astrophysics Data System (ADS)

    Wu, Yan; Fu, Fangmeng; Lian, Yuane; Nie, Yuting; Zhuo, Shuangmu; Wang, Chuan; Chen, Jianxin

    2015-02-01

    Clinical imaging techniques for diagnosing breast cancer mainly include X-ray mammography, ultrasound, and magnetic resonance imaging (MRI), which have respective drawbacks. Multiphoton microscopy (MPM) has become a potentially attractive optical technique to bridge the current gap in clinical utility. In this paper, MPM was used to image normal and ductal cancerous breast tissues, based on two-photon excited fluorescence (TPEF) and second harmonic generation (SHG). Our results showed that MPM has the ability to exhibit the microstructure of normal breast tissue, ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) lesions at the molecular level comparable to histopathology. These findings indicate that, with integration of MPM into currently accepted clinical imaging system, it has the potential to make a real-time histological diagnosis of mammary ductal carcinoma in vivo.

  5. Enhanced environmental performance of fiber optic gyroscope by an adhesive potting technology.

    PubMed

    Chen, Jun; Ding, Nengwen; Li, Zhifeng; Wang, Wei

    2015-09-10

    An adhesive potting technology for fiber coils of a fiber optic gyroscope (FOG) is proposed. The fiber coil is immersed in liquid adhesive with superior mechanical properties. The internal air is first removed completely by vacuum pumping, and the adhesive is then evenly pressed into the fiber coil under pressure. The potted fiber core is prepared by ladder-type temperature curing and a stress-release process. With this potting technology, the vibration performance of an FOG is greatly improved and, at the same time, will not lead to degradation of its temperature performance. Using this potting technique of adhesive impregnation, the adaptability of FOGs will be enhanced.

  6. Impact of green technologies in optical networks case study: green wireless optical broadband access network

    NASA Astrophysics Data System (ADS)

    Puche, William S.; Sierra, Javier E.

    2014-09-01

    This article analyzes the current state of green technologies in optical telecommunications networks, analyzing in detail the basic structure of a hybrid network (Optical-Wireless), taking into account energy consumption by proposing a mathematical model is presented to establish the optimum number of ONUs in a network.

  7. Increase in the compensated field of view with a double-conjugate adaptive-optics system.

    PubMed

    Baharav, Y; Shamir, J

    1995-04-20

    We analyze and quantify the capabilities and limitations of a double-conjugate adaptive-optics system. In the proposed system the contribution of two turbulent layers is treated separately, with Rayleigh guide stars for the bottom layer, sodium guide stars for the top layer, and two adaptive mirrors conjugate to the respective layers. The system substantially increases the compensated field of view. We give calculated results for the estimated number of guide stars needed, the wave-front sensor, and the adaptive-mirror resolution. Simulation results are also presented, and the residual error remaining after correction in our proposed system is compared with a conventional single-adaptive-mirror system.

  8. 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.

  9. Gregorian optical system with non-linear optical technology for protection against intense optical transients

    DOEpatents

    Ackermann, Mark R.; Diels, Jean-Claude M.

    2007-06-26

    An optical system comprising a concave primary mirror reflects light through an intermediate focus to a secondary mirror. The secondary mirror re-focuses the image to a final image plane. Optical limiter material is placed near the intermediate focus to optically limit the intensity of light so that downstream components of the optical system are protected from intense optical transients. Additional lenses before and/or after the intermediate focus correct optical aberrations.

  10. Final Report: Deconvolution of Adaptive Optics Images of Titan, Neptune, and Uranus

    SciTech Connect

    Gibbard, S; Marchis, F

    2002-12-20

    This project involved images of Titan, Neptune, and Uranus obtained using the 10-meter W.M. Keck II Telescope and its adaptive optics system. An adaptive optics system corrects for turbulence in the Earth's atmosphere by sampling the wavefront and applying a correction based on the distortion measured for a known source within the same isoplanatic patch as the science target (for example, a point source such as a star). Adaptive optics can achieve a 10-fold increase in resolution over that obtained by images without adaptive optics (for example, Saturn's largest moon Titan is unresolved without adaptive optics but at least 10 resolution elements can be obtained across the disk in Keck adaptive optics images). The adaptive optics correction for atmospheric turbulence is not perfect; a point source is converted to a diffraction-limited core surrounded by a ''halo''. This halo is roughly the size and shape of the uncorrected point spread function one would observe without adaptive optics. In order to enhance the sharpness of the Keck images it is necessary to apply a deconvolution algorithm to the data. Many such deconvolution algorithms exist such as maximum likelihood and maximum entropy. These algorithms suffer to various degrees from noise amplification and creation of artifacts near sharp edges (''ringing''). In order to deconvolve the Keck images I have applied an algorithm specifically developed for observations of planetary bodies, the myopic deconvolution algorithm MISTRAL (''Myopic Iterative STep-preserving Restoration ALgorithm'') (Conan et al. 1998, 2000). MISTRAL was developed by ONERA (Office National d'Etudes et de Recherches Aerospatiales) and has been extensively tested on simulated and real AO observations, including observations of Titan (Coustenis et al.2001), Io (Marchis et al.2002, 2001), and asteroids (Hestroffer et al.2001, Rosenberg et al.2001, Makhoul et al.2001). Compared to more classical methods, MISTRAL avoids noise amplification and

  11. Magnetic smart material application to adaptive x-ray optics

    NASA Astrophysics Data System (ADS)

    Ulmer, M. P.; Graham, Michael E.; Vaynman, Semyon; Cao, J.; Takacs, Peter Z.

    2010-09-01

    We discuss a technique of shape modification that can be applied to thin walled ({100-400 micron thickness) electroformed replicated optics or slumped glass optics to improve the near net shape of the mirror as well as the midfrequency ripple. The process involves sputter deposition of a magnetic smart material (MSM) film onto a permanently magnetic material. The MSM material exhibits strains about 400 times stronger than ordinary ferromagnetic materials. The deformation process involves a magnetic write head which traverses the surface, and under the guidance of active metrology feedback, locally magnetizes the surface to impart strain where needed. Designs and basic concepts as applied to space borne X-ray optics will be described.

  12. Characterization and annealing of high-stroke monolithic gold MEMS deformable mirror for adaptive optics

    NASA Astrophysics Data System (ADS)

    Fernández, Bautista; Kubby, Joel

    2011-03-01

    Adaptive optics for the next generation of extremely large telescopes (30 - 50 meter diameter primary mirrors) requires high-stroke (10 microns), high-order (100x100) deformable mirrors at lower-cost than current technology. Lowering the cost while improving the performance of deformable mirrors is possible using Micro-Electro-Mechanical Systems (MEMS) technology. In this paper the fabrication and testing of an array of high-stroke gold MEMS X-beam actuators attached to a continuous gold facesheet will be described. Both the actuator and the facesheet were fabricated monolithically in gold plated onto a thermally matched ceramic-glass substrate (WMS-15) using a high-aspect ratio fabrication process. Continuous facesheets that are deformed due to stress gradients have been annealed at high temperature and for an extended amount of time. The facesheet was flattened to the point where features such as etch holes and support post topography were easily distinguishable. Initial root-mean-square (RMS) topography at center of facesheet attached to a 16x16 X-beam actuator array with 1mm pitch was measured to be ~13.8μm. After annealing, the surface topography was measured to be ~1.0μm.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  14. Adaptive optical transmitter and receiver for space communication through thin clouds.

    PubMed

    Arnon, S; Kopeika, N S

    1997-03-20

    Optical space communication from satellite to ground or air to air consists of clouds as part of communication channels. Propagation of optical pulses through clouds causes widening and deformation in the time domain and attenuation of the pulse radiant power. These effects decrease the received signal and limit the information bandwidth of the communication system. Having dealt with the other effects previously, here we concentrate on pulse broadening in the time domain. We derive a mathematical model of an adaptive optical communication system with a multiscattering channel (atmospheric cloud). We use knowledge about the impulse response function of the cloud to adapt the communication parameters to the transfer function of the cloud. The communication system includes a receiver and a transmitter. We adapted the transmitter to atmospheric conditions by changing the bit error rate. One can adapt the receiver to the atmospheric condition by changing the parameters of the detector and the filter. An example for a practical communication system between a low Earth orbit satellite and a ground station cover by cloud is given. Comparison and analysis of an adaptive and semiadaptive system with cloud channels are presented. Our conclusion is that in some cases only by such adaptive methods is optical communication possible.

  15. Packet Transport Technologies for Optical Networks

    NASA Astrophysics Data System (ADS)

    Lometti, Alberto; Busi, Italo; Grandi, Pietro; Sestito, Vincenzo; Paparella, Andrea

    The purpose of a transport network is to provide a reliable aggregation and transport infrastructure for any client traffic type, in any scale, at the lowest cost per bit. With the growth of packet services, operators are transforming their network infrastructures while looking at reducing capital expenditures and maximizing operational savings. In that scope, new technologies are emerging such as transport multi-protocol label switching and provider backbone transport. This article outlines the state of the art for packet-based transport technologies, comparing them and highlighting the key factors.

  16. "High Angular Resolution Observations of Protoplanetary Disks with Adaptive Optics"

    NASA Technical Reports Server (NTRS)

    Roddier, Francois

    1999-01-01

    Significant results were obtained and published in the literature. The first optical detection of a circumbinary disk was reported in the ApJ at millimetric wavelengths. The size and inclination of this disk were found to be consistent with millimetric observations. Evidence was found for a cavity inside the disk as theory predicts from dust clearing by the stellar companion.

  17. Optical-I/O packaging technologies for chip- and board-level optical interconnects

    NASA Astrophysics Data System (ADS)

    Ishii, Yuzo

    2002-09-01

    As silicon LSIs become more densely integrated and the bit rates between them increase, traditional printed circuit boards present problems similar to electrical cables, which are already a bottleneck to cabinet interconnection. These problems include limited line length, poor flexibility in layout design, power dissipation, and crosstalk (EMI). One promising solution to these on-board electrical interconnection bottlenecks is to use optical interconnection technology at the chip level. Making chip-level optical interconnections practical requires revolutionary changes in optoelectronics packaging; the packaging must not only keep pace with silicon LSI capabilities but should also inherit the advantages of today?fs mature electronics packaging and manufacturability technologies. To meet these requirements, we developed novel optical-I/O packages for low-cost chip-to-chip optical interconnections. Unlike conventional optical packages, our packages are fully compatible with surface-mount technology (SMT) because they do not need optical connectors. The packages free users from all on-board connection work and fiber management. Using the developed optical-I/O packages, in which a VCSEL/PD array is mounted at the bottom, chip-to-chip parallel optical interconnection through a polymer waveguide array is demonstrated.

  18. Parallel optics technology assessment for the versatile link project

    SciTech Connect

    Chramowicz, J.; Kwan, S.; Rivera, R.; Prosser, A.; /Fermilab

    2011-01-01

    This poster describes the assessment of commercially available and prototype parallel optics modules for possible use as back end components for the Versatile Link common project. The assessment covers SNAP12 transmitter and receiver modules as well as optical engine technologies in dense packaging options. Tests were performed using vendor evaluation boards (SNAP12) as well as custom evaluation boards (optical engines). The measurements obtained were used to compare the performance of these components with single channel SFP+ components operating at a transmission wavelength of 850 nm over multimode fibers.

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

    NASA Astrophysics Data System (ADS)

    Adie, Steven G.; Mulligan, Jeffrey A.

    2016-03-01

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

  20. 3D imaging of cone photoreceptors over extended time periods using optical coherence tomography with adaptive optics

    NASA Astrophysics Data System (ADS)

    Kocaoglu, Omer P.; Lee, Sangyeol; Jonnal, Ravi S.; Wang, Qiang; Herde, Ashley E.; Besecker, Jason; Gao, Weihua; Miller, Donald T.

    2011-03-01

    Optical coherence tomography with adaptive optics (AO-OCT) is a highly sensitive, noninvasive method for 3D imaging of the microscopic retina. The purpose of this study is to advance AO-OCT technology by enabling repeated imaging of cone photoreceptors over extended periods of time (days). This sort of longitudinal imaging permits monitoring of 3D cone dynamics in both normal and diseased eyes, in particular the physiological processes of disc renewal and phagocytosis, which are disrupted by retinal diseases such as age related macular degeneration and retinitis pigmentosa. For this study, the existing AO-OCT system at Indiana underwent several major hardware and software improvements to optimize system performance for 4D cone imaging. First, ultrahigh speed imaging was realized using a Basler Sprint camera. Second, a light source with adjustable spectrum was realized by integration of an Integral laser (Femto Lasers, λc=800nm, ▵λ=160nm) and spectral filters in the source arm. For cone imaging, we used a bandpass filter with λc=809nm and ▵λ=81nm (2.6 μm nominal axial resolution in tissue, and 167 KHz A-line rate using 1,408 px), which reduced the impact of eye motion compared to previous AO-OCT implementations. Third, eye motion artifacts were further reduced by custom ImageJ plugins that registered (axially and laterally) the volume videos. In two subjects, cone photoreceptors were imaged and tracked over a ten day period and their reflectance and outer segment (OS) lengths measured. High-speed imaging and image registration/dewarping were found to reduce eye motion to a fraction of a cone width (1 μm root mean square). The pattern of reflections in the cones was found to change dramatically and occurred on a spatial scale well below the resolution of clinical instruments. Normalized reflectance of connecting cilia (CC) and OS posterior tip (PT) of an exemplary cone was 54+/-4, 47+/-4, 48+/-6, 50+/-5, 56+/-1% and 46+/-4, 53+/-4, 52+/-6, 50+/-5, 44

  1. PLANNING FOR OPTICAL DISK TECHNOLOGY WITH DIGITAL CARTOGRAPHY.

    USGS Publications Warehouse

    Light, Donald L.

    1984-01-01

    Progress in the computer field continues to suggest that the transition from traditional analog mapping systems to digital systems has become a practical possibility. A major shortfall that still exists in digital systems is the need for very large mass storage capacity. The decade of the 1980's has introduced laser optical disk storage technology, which may be the breakthrough needed for mass storage. This paper addresses system concepts for digital cartography during the transition period. Emphasis is placed on determining U. S. Geological Survey mass storage requirements and introducing laser optical disk technology for handling storage problems for digital data in this decade.

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

    NASA Astrophysics Data System (ADS)

    Foor, Wesley E.; Neifeld, Mark A.

    1995-11-01

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

  3. Off-the-shelf real-time computers for next-generation adaptive optics

    NASA Astrophysics Data System (ADS)

    Hippler, Stefan; Looze, Douglas P.; Gaessler, Wolfgang

    2004-10-01

    The performance of adaptive optics systems for existing as well as future giant telescopes heavily depends on the number of active wavefront compensating elements, the spatial, and the temporal sampling of the distorted incoming wavefront. In a phase-A study for an extreme adaptive optics system for the VLT (CHEOPS) as well as for LINC-NIRVANA a fizeau interferometer aboard LBT with a multi-conjugated adaptive optics system, we investigate how today's off-the-shelf computers compare in terms of floating point computing power, memory bandwidth, input/output bandwidth and real-time behavior. We address questions like how level three cache can impact the memory bandwidth, what matrix-vector multiplication performance is achievable, and what can we learn from standard benchmarks running on different architectures.

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

    PubMed

    Wang, Lianqi; Andersen, David; Ellerbroek, Brent

    2012-06-01

    The scientific productivity of laser guide star adaptive optics systems strongly depends on the sky coverage, which describes the probability of finding natural guide stars for the tip/tilt wavefront sensor(s) to achieve a certain performance. Knowledge of the sky coverage is also important for astronomers planning their observations. In this paper, we present an efficient method to compute the sky coverage for the laser guide star multiconjugate adaptive optics system, the Narrow Field Infrared Adaptive Optics System (NFIRAOS), being designed for the Thirty Meter Telescope project. We show that NFIRAOS can achieve more than 70% sky coverage over most of the accessible sky with the requirement of 191 nm total rms wavefront. PMID:22695611

  5. Near infra-red astronomy with adaptive optics and laser guide stars at the Keck Observatory

    SciTech Connect

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

    1995-08-03

    A laser guide star adaptive optics system is being built for the W. M. Keck Observatory`s 10-meter Keck II telescope. Two new near infra-red instruments will be used with this system: a high-resolution camera (NIRC 2) and an echelle spectrometer (NIRSPEC). The authors describe the expected capabilities of these instruments for high-resolution astronomy, using adaptive optics with either a natural star or a sodium-layer laser guide star as a reference. They compare the expected performance of these planned Keck adaptive optics instruments with that predicted for the NICMOS near infra-red camera, which is scheduled to be installed on the Hubble Space Telescope in 1997.

  6. US long distance fiber optic networks: Technology, evolution and advanced concepts. Volume 2: Fiber optic technology and long distance networks

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The study projects until 2000 the evolution of long distance fiber optic networks in the U.S. Volume 1 is the Executive Summary. Volume 2 focuses on fiber optic components and systems that are directly related to the operation of long-haul networks. Optimistic, pessimistic and most likely scenarios of technology development are presented. The activities of national and regional companies implementing fiber long haul networks are also highlighted, along with an analysis of the market and regulatory forces affecting network evolution. Volume 3 presents advanced fiber optic network concept definitions. Inter-LATA traffic is quantified and forms the basis for the construction of 11-, 15-, 17-, and 23-node networks. Using the technology projections from Volume 2, a financial model identifies cost drivers and determines circuit mile costs between any two LATAs. A comparison of fiber optics with alternative transmission concludes the report.

  7. Improving Adaptive Learning Technology through the Use of Response Times

    ERIC Educational Resources Information Center

    Mettler, Everett; Massey, Christine M.; Kellman, Philip J.

    2011-01-01

    Adaptive learning techniques have typically scheduled practice using learners' accuracy and item presentation history. We describe an adaptive learning system (Adaptive Response Time Based Sequencing--ARTS) that uses both accuracy and response time (RT) as direct inputs into sequencing. Response times are used to assess learning strength and…

  8. Benefit of adaptive FEC in shared backup path protected elastic optical network.

    PubMed

    Guo, Hong; Dai, Hua; Wang, Chao; Li, Yongcheng; Bose, Sanjay K; Shen, Gangxiang

    2015-07-27

    We apply an adaptive forward error correction (FEC) allocation strategy to an Elastic Optical Network (EON) operated with shared backup path protection (SBPP). To maximize the protected network capacity that can be carried, an Integer Linear Programing (ILP) model and a spectrum window plane (SWP)-based heuristic algorithm are developed. Simulation results show that the FEC coding overhead required by the adaptive FEC scheme is significantly lower than that needed by a fixed FEC allocation strategy resulting in higher network capacity for the adaptive strategy. The adaptive FEC allocation strategy can also significantly outperform the fixed FEC allocation strategy both in terms of the spare capacity redundancy and the average FEC coding overhead needed per optical channel. The proposed heuristic algorithm is efficient and not only performs closer to the ILP model but also does much better than the shortest-path algorithm. PMID:26367673

  9. Benefit of adaptive FEC in shared backup path protected elastic optical network.

    PubMed

    Guo, Hong; Dai, Hua; Wang, Chao; Li, Yongcheng; Bose, Sanjay K; Shen, Gangxiang

    2015-07-27

    We apply an adaptive forward error correction (FEC) allocation strategy to an Elastic Optical Network (EON) operated with shared backup path protection (SBPP). To maximize the protected network capacity that can be carried, an Integer Linear Programing (ILP) model and a spectrum window plane (SWP)-based heuristic algorithm are developed. Simulation results show that the FEC coding overhead required by the adaptive FEC scheme is significantly lower than that needed by a fixed FEC allocation strategy resulting in higher network capacity for the adaptive strategy. The adaptive FEC allocation strategy can also significantly outperform the fixed FEC allocation strategy both in terms of the spare capacity redundancy and the average FEC coding overhead needed per optical channel. The proposed heuristic algorithm is efficient and not only performs closer to the ILP model but also does much better than the shortest-path algorithm.

  10. Implementation and Evaluation of Multiple Adaptive Control Technologies for a Generic Transport Aircraft Simulation

    NASA Technical Reports Server (NTRS)

    Campbell, Stefan F.; Kaneshige, John T.; Nguyen, Nhan T.; Krishakumar, Kalmanje S.

    2010-01-01

    Presented here is the evaluation of multiple adaptive control technologies for a generic transport aircraft simulation. For this study, seven model reference adaptive control (MRAC) based technologies were considered. Each technology was integrated into an identical dynamic-inversion control architecture and tuned using a methodology based on metrics and specific design requirements. Simulation tests were then performed to evaluate each technology s sensitivity to time-delay, flight condition, model uncertainty, and artificially induced cross-coupling. The resulting robustness and performance characteristics were used to identify potential strengths, weaknesses, and integration challenges of the individual adaptive control technologies

  11. Study of large adaptive arrays for space technology applications

    NASA Technical Reports Server (NTRS)

    Berkowitz, R. S.; Steinberg, B.; Powers, E.; Lim, T.

    1977-01-01

    The research in large adaptive antenna arrays for space technology applications is reported. Specifically two tasks were considered. The first was a system design study for accurate determination of the positions and the frequencies of sources radiating from the earth's surface that could be used for the rapid location of people or vehicles in distress. This system design study led to a nonrigid array about 8 km in size with means for locating the array element positions, receiving signals from the earth and determining the source locations and frequencies of the transmitting sources. It is concluded that this system design is feasible, and satisfies the desired objectives. The second task was an experiment to determine the largest earthbound array which could simulate a spaceborne experiment. It was determined that an 800 ft array would perform indistinguishably in both locations and it is estimated that one several times larger also would serve satisfactorily. In addition the power density spectrum of the phase difference fluctuations across a large array was measured. It was found that the spectrum falls off approximately as f to the minus 5/2 power.

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

    PubMed

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

    2012-03-01

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

  13. Interferometric adaptive optics for high-power laser beam correction in fast ignition experiments

    SciTech Connect

    Homoelle, D C; Baker, K L; Patel, P K; Utterback, E; Rushford, M C; Siders, C W; Barty, C J

    2009-10-22

    We present the design for a high-speed adaptive optics system that will be used to achieve the necessary laser pointing and beam-quality performance for initial fast-ignition coupling experiments. This design makes use of a 32 x 32 pixellated MEMS device as the adaptive optic and a two-channel interferometer as the wave-front sensor. We present results from a system testbed that demonstrates improvement of the Strehl ratio from 0.09 to 0.61 and stabilization of beam pointing from {approx}75{micro}rad to <2{micro}rad.

  14. A Phase-Shifting Zernike Wavefront Sensor for the Palomar P3K Adaptive Optics System

    NASA Technical Reports Server (NTRS)

    Wallace, J. Kent; Crawford, Sam; Loya, Frank; Moore, James

    2012-01-01

    A phase-shifting Zernike wavefront sensor has distinct advantages over other types of wavefront sensors. Chief among them are: 1) improved sensitivity to low-order aberrations and 2) efficient use of photons (hence reduced sensitivity to photon noise). We are in the process of deploying a phase-shifting Zernike wavefront sensor to be used with the realtime adaptive optics system for Palomar. Here we present the current state of the Zernike wavefront sensor to be integrated into the high-order adaptive optics system at Mount Palomar's Hale Telescope.

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

    NASA Astrophysics Data System (ADS)

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

    2001-05-01

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

  16. On-sky demonstration of optimal control for adaptive optics at Palomar Observatory.

    PubMed

    Tesch, Jonathan; Truong, Tuan; Burruss, Rick; Gibson, Steve

    2015-04-01

    High-order adaptive optics systems often suffer from significant computational latency, which ultimately limits the temporal error rejection bandwidth when classical controllers are employed. This Letter presents results from an on-sky, real-time implementation of an optimal controller on the PALM-3000 adaptive optics system at Palomar Observatory. The optimal controller is computed directly from open-loop wavefront measurements using a multichannel subspace system identification algorithm, and mitigates latency by explicitly predicting incident turbulence. Experimental results show a significant reduction in the residual wavefront error over the controlled spatial modes, illustrating the superior performance of the optimal control approach versus the nominal integral control architecture.

  17. In vivo fluorescent imaging of the mouse retina using adaptive optics

    PubMed Central

    Biss, David P.; Sumorok, Daniel; Burns, Stephen A.; Webb, Robert H.; Zhou, Yaopeng; Bifano, Thomas G.; Côté, Daniel; Veilleux, Israel; Zamiri, Parisa; Lin, Charles P.

    2009-01-01

    In vivo imaging of the mouse retina using visible and near infrared wavelengths does not achieve diffraction-limited resolution due to wavefront aberrations induced by the eye. Considering the pupil size and axial dimension of the eye, it is expected that unaberrated imaging of the retina would have a transverse resolution of 2 μm. Higher-order aberrations in retinal imaging of human can be compensated for by using adaptive optics. We demonstrate an adaptive optics system for in vivo imaging of fluorescent structures in the retina of a mouse, using a microelectromechanical system membrane mirror and a Shack–Hartmann wavefront sensor that detects fluorescent wavefront. PMID:17308593

  18. Interferometric adaptive optics for high-power laser beam correction in fast ignition experiments

    NASA Astrophysics Data System (ADS)

    Homoelle, D.; Baker, K. L.; Patel, P. K.; Utterback, E.; Rushford, M. C.; Siders, C. W.; Barty, C. P. J.

    2010-08-01

    We present the design for a high-speed adaptive optics system that will be used to achieve the necessary laser pointing and beam-quality performance for initial fast-ignition coupling experiments. This design makes use of a 32×32 pixellated MEMS device as the adaptive optic and a two-channel interferometer as the wave-front sensor. We present results from a system testbed that demonstrates improvement of the Strehl ratio from 0.09 to 0.61 and stabilization of beam pointing from ~75μrad to <2μrad.

  19. An Adaptive Optics Survey for Companions to Stars with Extra-Solar Planets

    SciTech Connect

    Lloyd, J.P.; Liu, M.C.; Graham, J.R.; Enoch, M.; Kalas, P.; Marcy, G.W.; Fischer, D.; Patience, J.; Macintosh, B.; Gavel, D.T.; Olivier, S.S.; Max, C.E.; White, R.; Ghez, A.M.; McLean, I.S.

    2000-11-27

    We have undertaken an adaptive optics imaging survey of extrasolar planetary systems and stars showing interesting radial velocity trends from high precision radial velocity searches. Adaptive Optics increases the resolution and dynamic range of an image, substantially improving the detectability of faint close companions. This survey is sensitive to objects less luminous than the bottom of the main sequence at separations as close as 1 inch. We have detected stellar companions to the planet bearing stars HD 114762 and Tau Boo. We have also detected a companion to the non-planet bearing star 16 Cyg A.

  20. Adaptive Optics Survey for Companions to stars with Extra-Solar Planets

    SciTech Connect

    Lloyd, J P; Liu, M C; Graham, J R; Enoch, M; Kalas, P; Marcy, G W; Fischer, D; Patience, J; Macintosh, B; Gavel, D T; Olivier, S S; Max, C E; White, R; Ghez, A M; McLean, I S

    2000-11-27

    We have undertaken an adaptive optics imaging survey of extrasolar planetary systems and stars showing interesting radial velocity trends from high precision radial velocity searches. Adaptive Optics increases the resolution and dynamic range of an image, substantially improving the detectability of faint close companions. This survey is sensitive to objects less luminous than the bottom of the main sequence at separations as close as 1 inch. We have detected stellar companions to the planet bearing stars HD 114762 and Tau Boo. We have also detected a companion to the non-planet bearing star 16 Cyg A.

  1. Application of adaptive optics in retinal imaging: a quantitative and clinical comparison with standard cameras

    NASA Astrophysics Data System (ADS)

    Barriga, E. S.; Erry, G.; Yang, S.; Russell, S.; Raman, B.; Soliz, P.

    2005-04-01

    Aim: The objective of this project was to evaluate high resolution images from an adaptive optics retinal imager through comparisons with standard film-based and standard digital fundus imagers. Methods: A clinical prototype adaptive optics fundus imager (AOFI) was used to collect retinal images from subjects with various forms of retinopathy to determine whether improved visibility into the disease could be provided to the clinician. The AOFI achieves low-order correction of aberrations through a closed-loop wavefront sensor and an adaptive optics system. The remaining high-order aberrations are removed by direct deconvolution using the point spread function (PSF) or by blind deconvolution when the PSF is not available. An ophthalmologist compared the AOFI images with standard fundus images and provided a clinical evaluation of all the modalities and processing techniques. All images were also analyzed using a quantitative image quality index. Results: This system has been tested on three human subjects (one normal and two with retinopathy). In the diabetic patient vascular abnormalities were detected with the AOFI that cannot be resolved with the standard fundus camera. Very small features, such as the fine vascular structures on the optic disc and the individual nerve fiber bundles are easily resolved by the AOFI. Conclusion: This project demonstrated that adaptive optic images have great potential in providing clinically significant detail of anatomical and pathological structures to the ophthalmologist.

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

    SciTech Connect

    Poyneer, L A; Veran, J

    2008-06-04

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

  3. Adaptive optics and optical structures; Proceedings of the Meeting, European Congress on Optics, 3rd, The Hague, Netherlands, Mar. 12-14, 1990

    NASA Technical Reports Server (NTRS)

    Tyson, Robert K. (Editor); Schulte In Den Baeumen, J. (Editor)

    1990-01-01

    The present conference on adaptive optics (AO) and optical structures addresses AO systems and controls, AO components, nonlinear optics applications to AO, astronomical applications of AO, large telescopes and optical alignment, as well as the wavefront control experiment for the use of AO in beam propagation. Specific references are made to applications of electromagnetic theory in optics, theoretical studies of system performance and design parameters, Hartmann-Shack wavefront sensing, the use of ray-based techniques in cophasing segmented mirrors, the use of a phase-conjugating mirror for real-time phase visualization, and the absolute instability of oppositely directed waves with respect to a high-reflectivity phase-conjugate mirror. Also addressed are automatic control systems, precision segmented reflectors, AO system creation, the VLT's 8.2-m primary mirrors, an optical 12-m telescope, alignment optimization via the Talbot effect, and a combination of interferometry and ray-tracing analysis.

  4. RF Photonic Technology in Optical Fiber Links

    NASA Astrophysics Data System (ADS)

    Chang, William S. C.

    2007-06-01

    List of contributors; Introduction and preface; 1. Figures of merit and performance analysis of photonic microwave links Charles Cox and William S. C. Chang; 2. RF subcarrier links in local access networks Xiaolin Lu; 3. Analog modulation of semiconductor lasers Joachim Piprek and John E. Bowers; 4. LiNbO3 external modulators and their use in high performance analog links Gary E. Betts; 5. Broadband traveling wave modulators in LiNbO3 Marta M. Howerton and William K. Burns; 6. Multiple quantum well electroabsorption modulators for RF photonic links William S. C. Chang; 7. Polymer modulators for RF photonics Timothy Van Eck; 8. Photodiodes for high performance analog links P. K. L. Yu and Ming C. Wu; 9. Opto-electronic oscillators X. Steve Yao; 10. Photonic link techniques for microwave frequency conversion Stephen A. Pappert, Roger Helkey and Ronald T. Logan Jr; 11. Antenna-coupled millimeter-wave electro-optical modulators William B. Bridges; 12. System design and performance of wideband photonic phased array antennas Greg L. Tangonan, Willie Ng, Daniel Yap and Ron Stephens; Acknowledgements; References; Index.

  5. Easing wave optics understanding through technology

    NASA Astrophysics Data System (ADS)

    Garg, Amit; Kachru, Priyanka; Singh, Shatakshi; Tiwary, Rishabh

    2014-09-01

    As part of the course curriculum of Physics of class XII, students do a comprehensive theoretical study about the wave nature of light specially related to interference, diffraction and polarisation. But, these studies are not backed up by any experiments. This makes the understanding of these complex topics very difficult. The purpose of the present outreach activity is to make students do many hands-on experiments on the above topics. The experiments have been designed keeping in mind the various theoretical concepts taught to the students. The studies are helpful in making the students understand fringe formation, intensity variation across the fringes formed helping them compare interference and diffraction fringes, dependence of fringe separation on various parameters, linear polarization, Malus' law and Brewster's law. The tools used to perform the experiments include He-Ne/ diode laser(s), Laptop/Digital Storage Oscilloscope, CCD, various optical components like set of polarisers and analysers, glass plate and hardware components like single slit and double slit. The class XII students are divided into batches and each batch is handled by a team of three University of Delhi at ANDC SPIE student chapter members. The gains of the activity are measured through pre and post-tests.

  6. New Optical Imaging Technologies for Bladder Cancer: Considerations and Perspectives

    PubMed Central

    Liu, Jen-Jane; Droller, Michael J.; Liao, Joseph C.

    2014-01-01

    Purpose Bladder cancer presents as a spectrum of different diatheses. Accurate assessment for individualized treatment depends on initial diagnostic accuracy. Detection relies on white light cystoscopy accuracy and comprehensiveness. Aside from invasiveness and potential risks, white light cystoscopy shortcomings include difficult flat lesion detection, precise tumor delineation to enable complete resection, inflammation and malignancy differentiation, and grade and stage determination. Each shortcoming depends on surgeon ability and experience with the technology available for visualization and resection. Fluorescence cystoscopy/photodynamic diagnosis, narrow band imaging, confocal laser endomicroscopy and optical coherence tomography address the limitations and have in vivo feasibility. They detect suspicious lesions (photodynamic diagnosis and narrow band imaging) and further characterize lesions (optical coherence tomography and confocal laser endomicroscopy). We analyzed the added value of each technology beyond white light cystoscopy and evaluated their maturity to alter the cancer course. Materials and Methods Detailed PubMed® searches were done using the terms “fluorescence cystoscopy,” “photodynamic diagnosis,” “narrow band imaging,” “optical coherence tomography” and “confocal laser endomicroscopy” with “optical imaging,” “bladder cancer” and “urothelial carcinoma.” Diagnostic accuracy reports and all prospective studies were selected for analysis. We explored technological principles, preclinical and clinical evidence supporting nonmuscle invasive bladder cancer detection and characterization, and whether improved sensitivity vs specificity translates into improved correlation of diagnostic accuracy with recurrence and progression. Emerging preclinical technologies with potential application were reviewed. Results Photodynamic diagnosis and narrow band imaging improve nonmuscle invasive bladder cancer detection, including

  7. Development of a mesospheric sodium laser beacon for atmospheric adaptive optics. (Reannouncement with new availability information)

    SciTech Connect

    Jeys, T.H.

    1991-12-31

    The authors have developed laser sources of sodium-resonance radiation based on the sum-frequency mixing of Nd:YAG laser radiation. The sources are suitable for generating a fluorescence spot in the earth`s mesospheric sodium layer for use in adaptive optics compensation. Taking into account the sodium fluorescence lifetime, Doppler broadening, hyperfine structure, radiative saturation, optical pumping, and radiation pressure, we can optimize the intensity of the fluorescence by using spectral and temporal tailoring of the laser radiation.

  8. Solar Multi-Conjugate Adaptive Optics at the Dunn Solar Telescope

    NASA Astrophysics Data System (ADS)

    Rimmele, T.; Hegwer, S.; Richards, K.; Woeger, F.

    Solar adaptive optics has become an indispensable tool at ground based solar telescopes. Driven by the quest for ever higher spatial resolution observations of the Sun solar adaptive optics are now operated routinely at major ground based solar telescopes. The current high-resolution solar telescopes, such as the Dunn Solar Telescope (DST), are in the one-meter class and utilize AO for >95 % of the observing time to achieve the diffraction limit at visible and NIR wavelengths. Solar AO [1,2] has revitalized ground-based solar astronomy at existing telescopes. The development of high-order solar AO that is capable of delivering high Strehl in the visible will be absolutely essential for next generation solar telescopes, such as the 4m aperture Advanced Technology Solar Telescope (ATST), which undoubtedly will revolutionize solar astronomy [3]. Solar observations are performed over an extended field of view. The limited size of the isoplanatic patch, over which conventional adaptive optics (AO) provides diffraction limited resolution is a severe limitation. Solar science would benefit greatly from AO correction over large field of views. A single sunspot typically has a size of about 30 arcsec; large active regions often cover a field of 2-3 arcmin. Figure 1 shows an image of solar granulation and embedded magnetic g-band bright points observed near the limb of the sun. The field of view is approximately 120"x 80". This diffraction limited image was recorded at the Dunn Solar Telescope with high order adaptive optics and post-processed using speckle interferometry. Post-processing is required to achieve the uniform, diffraction limited imaging over such an extended FOV. However, speckle interferometry as well as other post facto restoration methods typically rely on short exposure imaging, which in most cases can not be deployed when quantitative spectroscopy and polarimetry is performed, i.e., long exposures are required. Multi-conjugate adaptive optics (MCAO) is a

  9. Sodium Laser Guide Star Adaptive Optics Imaging Polarimetry of Herbig Ae/Be Stars

    SciTech Connect

    Perrin, M D; Graham, J R; Lloyd, J P; Kalas, P; Gates, E L; Gavel, D T; Pennington, D M; Max, C E

    2004-01-08

    The future of high-resolution ground-based optical and infrared astronomy requires the successful implementation of laser guide star adaptive optics systems. We present the first science results from the Lick Observatory sodium beacon laser guide star system. By coupling this system to a near-infrared (J;H;Ks bands) dual-channel imaging polarimeter, we achieve very high sensitivity to light scattered in the circumstellar enviroment of Herbig Ae/Be stars on scales of 100-300 AU. Observations of LkH{alpha} 198 reveal a highly polarized, biconical nebula 10 arcseconds in diameter (6000 AU) . We also observe a polarized jet-like feature associated with the deeply embedded source LkH{alpha} 198-IR. The star LkH{alpha} 233 presents a narrow, unpolarized dark lane dividing its characteristic butterfly-shaped polarized reflection nebulosity. This linear structure is oriented perpendicular to an optical jet and bipolar cavity and is consistent with the presence of an optically thick circumstellar disk blocking our direct view of the star. These data suggest that the evolutionary picture developed for the lower-mass T Tauri stars is also relevant to the Herbig Ae/Be stars and demonstrate the ability of laser guide star adaptive optics systems to obtain scientific results competitive with natural guide star adaptive optics or space-based telescopes.

  10. Adaptive optics applied to coherent anti-Stokes Raman scattering microscopy

    NASA Astrophysics Data System (ADS)

    Girkin, John M.; Poland, Simon P.; Wright, Amanda J.; Freudiger, Christian; Evans, Conor L.; Xie, X. Sunney

    2008-02-01

    We report on the use of adaptive optics in coherent anti-Stokes Raman scattering microscopy (CARS) to improve the image brightness and quality at increased optical penetration depths in biological material. The principle of the technique is to shape the incoming wavefront in such a way that it counteracts the aberrations introduced by imperfect optics and the varying refractive index of the sample. In recent years adaptive optics have been implemented in multiphoton and confocal microscopy. CARS microscopy is proving to be a powerful tool for non-invasive and label-free biomedical imaging with vibrational contrast. As the contrast mechanism is based on a 3 rd order non-linear optical process, it is highly susceptible to aberrations, thus CARS signals are commonly lost beyond the depth of ~100 μm in tissue. We demonstrate the combination of adaptive optics and CARS microscopy for deep-tissue imaging using a deformable membrane mirror. A random search optimization algorithm using the CARS intensity as the figure of merit determined the correct mirror-shape in order to correct for the aberrations. We highlight two different methods of implementation, using a look up table technique and by performing the optimizing in situ. We demonstrate a significant increase in brightness and image quality in an agarose/polystyrene-bead sample and white chicken muscle, pushing the penetration depth beyond 200 μm.

  11. Socio-Pedagogical Complex as a Pedagogical Support Technology of Students' Social Adaptation

    ERIC Educational Resources Information Center

    Sadovaya, Victoriya V.; Simonova, Galina I.

    2016-01-01

    The relevance of the problem stated in the article is determined by the need of developing technological approaches to pedagogical support of students' social adaptation. The purpose of this paper is to position the technological sequence of pedagogical support of students' social adaptation in the activities of the socio-pedagogical complex. The…

  12. Laser Electro-Optic Technology. Florida Vocational Program Guide.

    ERIC Educational Resources Information Center

    University of South Florida, Tampa. Dept. of Adult and Vocational Education.

    This program guide identifies primary considerations in the organization, operation, and evaluation of a laser electro-optic technology program. An occupational description and program content are presented. A curriculum framework specifies the exact course title, course number, levels of instruction, major course content, laboratory activities,…

  13. Laser Electro-Optic Engineering Technology. Florida Vocational Program Guide.

    ERIC Educational Resources Information Center

    University of South Florida, Tampa. Dept. of Adult and Vocational Education.

    This program guide identifies particular considerations in the organization, operation, and evaluation of laser electro-optic engineering technology programs. Contents include an occupational description and information on the following: program content, including a curriculum framework that details major concepts and intended outcomes and a list…

  14. Optical detectors for GaAs MMIC integration: Technology assessment

    NASA Technical Reports Server (NTRS)

    Claspy, P. C.; Bhasin, K. B.

    1989-01-01

    Fiber optic links are being considered to transmit digital and analog signals in phased array antenna feed networks in space communications systems. The radiating elements in these arrays will be GaAs monolithic microwave integrated circuits (MMIC's) in numbers ranging from a few hundred to several thousand. If such optical interconnects are to be practical it appears essential that the associated components, including detectors, be monolithically integrated on the same chip as the microwave circuitry. The general issue of monolithic integration of microwave and optoelectronic components is addressed from the point of view of fabrication technology and compatibility. Particular attention is given to the fabrication technology of various types of GaAs optical detectors that are designed to operate at a wavelength of 830 nm.

  15. Adaptive spectral window sizes for extraction of diagnostic features from optical spectra

    NASA Astrophysics Data System (ADS)

    Kan, Chih-Wen; Lee, Andy Y.; Nieman, Linda T.; Sokolov, Konstantin; Markey, Mia K.

    2010-07-01

    We present an approach to adaptively adjust the spectral window sizes for optical spectra feature extraction. Previous studies extracted features from spectral windows of a fixed width. In our algorithm, piecewise linear regression is used to adaptively adjust the window sizes to find the maximum window size with reasonable linear fit with the spectrum. This adaptive windowing technique ensures the signal linearity in defined windows; hence, the adaptive windowing technique retains more diagnostic information while using fewer windows. This method was tested on a data set of diffuse reflectance spectra of oral mucosa lesions. Eight features were extracted from each window. We performed classifications using linear discriminant analysis with cross-validation. Using windowing techniques results in better classification performance than not using windowing. The area under the receiver-operating-characteristics curve for windowing techniques was greater than a nonwindowing technique for both normal versus mild dysplasia (MD) plus severe high-grade dysplasia or carcinama (SD) (MD+SD) and benign versus MD+SD. Although adaptive and fixed-size windowing perform similarly, adaptive windowing utilizes significantly fewer windows than fixed-size windows (number of windows per spectrum: 8 versus 16). Because adaptive windows retain most diagnostic information while reducing the number of windows needed for feature extraction, our results suggest that it isolates unique diagnostic features in optical spectra.

  16. Integrated Optical Switch Based on SOI-Technology

    NASA Astrophysics Data System (ADS)

    Aalto, T.; Heimala, P.; Katila, P.

    An integrated optical thermo-optic switch has been designed using silicon-on-insulator (SOI) waveguide technology. The switch consists of two cascaded waveguide couplers with thermo-optic heaters on the waveguide arms connecting the two couplers. A detailed modelling of the optical and thermal operation of the switch has been made. A single-mode ridge waveguide structure with large cross-section was designed. The fibre-waveguide mode coupling loss was calculated to be 0.6dB. According to the thermal modelling, a 3K temperature change is enough to switch the output state of the device. The switching time is expected to be 0.2ms and the electrical power consumption 120mW.

  17. A survey of adaptive control technology in robotics

    NASA Technical Reports Server (NTRS)

    Tosunoglu, S.; Tesar, D.

    1987-01-01

    Previous work on the adaptive control of robotic systems is reviewed. Although the field is relatively new and does not yet represent a mature discipline, considerable attention has been given to the design of sophisticated robot controllers. Here, adaptive control methods are divided into model reference adaptive systems and self-tuning regulators with further definition of various approaches given in each class. The similarity and distinct features of the designed controllers are delineated and tabulated to enhance comparative review.

  18. Adaptive Optics Imaging of Healthy and Abnormal Regions of Retinal Nerve Fiber Bundles of Patients With Glaucoma

    PubMed Central

    Chen, Monica F.; Chui, Toco Y. P.; Alhadeff, Paula; Rosen, Richard B.; Ritch, Robert; Dubra, Alfredo; Hood, Donald C.

    2015-01-01

    Purpose. To better understand the nature of glaucomatous damage of the macula, especially the structural changes seen between relatively healthy and clearly abnormal (AB) retinal regions, using an adaptive optics scanning light ophthalmoscope (AO-SLO). Methods. Adaptive optics SLO images and optical coherence tomography (OCT) vertical line scans were obtained on one eye of seven glaucoma patients, with relatively deep local arcuate defects on the 10-2 visual field test in one (six eyes) or both hemifields (one eye). Based on the OCT images, the retinal nerve fiber (RNF) layer was divided into two regions: (1) within normal limits (WNL), relative RNF layer thickness within mean control values ±2 SD; and (2) AB, relative thickness less than −2 SD value. Results. As seen on AO-SLO, the pattern of AB RNF bundles near the border of the WNL and AB regions differed across eyes. There were normal-appearing bundles in the WNL region of all eyes and AB-appearing bundles near the border with the AB region. This region with AB bundles ranged in extent from a few bundles to the entire AB region in the case of one eye. All other eyes had a large AB region without bundles. However, in two of these eyes, a few bundles were seen within this region of otherwise missing bundles. Conclusions. The AO-SLO images revealed details of glaucomatous damage that are difficult, if not impossible, to see with current OCT technology. Adaptive optics SLO may prove useful in following progression in clinical trials, or in disease management, if AO-SLO becomes widely available and easy to use. PMID:25574048

  19. Astrophysical Adaptation of Points, the Precision Optical Interferometer in Space

    NASA Technical Reports Server (NTRS)

    Reasenberg, Robert D.; Babcock, Robert W.; Murison, Marc A.; Noecker, M. Charles; Phillips, James D.; Schumaker, Bonny L.; Ulvestad, James S.; McKinley, William; Zielinski, Robert J.; Lillie, Charles F.

    1996-01-01

    POINTS (Precision Optical INTerferometer in Space) would perform microarcsecond optical astrometric measurements from space, yielding submicroarcsecond astrometric results from the mission. It comprises a pair of independent Michelson stellar interferometers and a laser metrology system that measures both the critical starlight paths and the angle between the baselines. The instrument has two baselines of 2 m, each with two subapertures of 35 cm; by articulating the angle between the baselines, it observes targets separated by 87 to 93 deg. POINTS does global astrometry, i.e., it measures widely separated targets, which yields closure calibration, numerous bright reference stars, and absolute parallax. Simplicity, stability, and the mitigation of systematic error are the central design themes. The instrument has only three moving-part mechanisms, and only one of these must move with sub-milliradian precision; the other two can tolerate a precision of several tenths of a degree. Optical surfaces preceding the beamsplitter or its fold flat are interferometrically critical; on each side of the interferometer, there are only three such. Thus, light loss and wavefront distortion are minimized. POINTS represents a minimalistic design developed ab initio for space. Since it is intended for astrometry, and therefore does not require the u-v-plane coverage of an imaging, instrument, each interferometer need have only two subapertures. The design relies on articulation of the angle between the interferometers and body pointing to select targets; the observations are restricted to the 'instrument plane.' That plane, which is fixed in the pointed instrument, is defined by the sensitive direction for the two interferometers. Thus, there is no need for siderostats and moving delay lines, which would have added many precision mechanisms with rolling and sliding parts that would be required to function throughout the mission. Further, there is no need for a third interferometer

  20. The 1994 Fiber Optic Sensors for Aerospace Technology (FOSAT) Workshop

    NASA Technical Reports Server (NTRS)

    Baumbick, Robert (Compiler); Adamovsky, Grigory (Compiler); Tuma, Meg (Compiler); Beheim, Glenn (Compiler); Sotomayor, Jorge (Compiler)

    1995-01-01

    The NASA Lewis Research Center conducted a workshop on fiber optic technology on October 18-20, 1994. The workshop objective was to discuss the future direction of fiber optics and optical sensor research, especially in the aerospace arena. The workshop was separated into four sections: (1) a Systems Section which dealt specifically with top level overall architectures for the aircraft and engine; (2) a Subsystems Section considered the parts and pieces that made up the subsystems of the overall systems; (3) a Sensor/Actuators section considered the status of research on passive optical sensors and optical powered actuators; and (4) Components Section which addressed the interconnects for the optical systems (e.g., optical connectors, optical fibers, etc.). This report contains the minutes of the discussion on the workshop, both in each section and in the plenary sessions. The slides used by a limited number of presenters are also included as presented. No attempt was made to homogenize this report. The view of most of the attendees was: (1) the government must do a better job of disseminating technical information in a more timely fashion; (2) enough work has been done on the components, and system level architecture definition must dictate what work should be done on components; (3) a Photonics Steering Committee should be formed to coordinate the efforts of government and industry in the photonics area, to make sure that programs complimented each other and that technology transferred from one program was used in other programs to the best advantage of the government and industry.