WorldWideScience

Sample records for adaptive optics systems

  1. Intelligent Optical Systems Using Adaptive Optics

    Science.gov (United States)

    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.

  2. Adaptive optics system application for solar telescope

    Science.gov (United States)

    Lukin, V. P.; Grigor'ev, V. M.; Antoshkin, L. V.; Botugina, N. N.; Emaleev, O. N.; Konyaev, P. A.; Kovadlo, P. G.; Krivolutskiy, N. P.; Lavrionova, L. N.; Skomorovski, V. I.

    2008-07-01

    The possibility of applying adaptive correction to ground-based solar astronomy is considered. Several experimental systems for image stabilization are described along with the results of their tests. Using our work along several years and world experience in solar adaptive optics (AO) we are assuming to obtain first light to the end of 2008 for the first Russian low order ANGARA solar AO system on the Big Solar Vacuum Telescope (BSVT) with 37 subapertures Shack-Hartmann wavefront sensor based of our modified correlation tracker algorithm, DALSTAR video camera, 37 elements deformable bimorph mirror, home made fast tip-tip mirror with separate correlation tracker. Too strong daytime turbulence is on the BSVT site and we are planning to obtain a partial correction for part of Sun surface image.

  3. Robust adaptive optics systems for vision science

    Science.gov (United States)

    Burns, S. A.; de Castro, A.; Sawides, L.; Luo, T.; Sapoznik, K.

    2018-02-01

    Adaptive Optics (AO) is of growing importance for understanding the impact of retinal and systemic diseases on the retina. While AO retinal imaging in healthy eyes is now routine, AO imaging in older eyes and eyes with optical changes to the anterior eye can be difficult and requires a control and an imaging system that is resilient when there is scattering and occlusion from the cornea and lens, as well as in the presence of irregular and small pupils. Our AO retinal imaging system combines evaluation of local image quality of the pupil, with spatially programmable detection. The wavefront control system uses a woofer tweeter approach, combining an electromagnetic mirror and a MEMS mirror and a single Shack Hartmann sensor. The SH sensor samples an 8 mm exit pupil and the subject is aligned to a region within this larger system pupil using a chin and forehead rest. A spot quality metric is calculated in real time for each lenslet. Individual lenslets that do not meet the quality metric are eliminated from the processing. Mirror shapes are smoothed outside the region of wavefront control when pupils are small. The system allows imaging even with smaller irregular pupils, however because the depth of field increases under these conditions, sectioning performance decreases. A retinal conjugate micromirror array selectively directs mid-range scatter to additional detectors. This improves detection of retinal capillaries even when the confocal image has poorer image quality that includes both photoreceptors and blood vessels.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-11-15

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

  5. Digital adaptive optics line-scanning confocal imaging system

    Science.gov (United States)

    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. Problems of Aero-optics and Adaptive Optical Systems: Analytical Review

    Directory of Open Access Journals (Sweden)

    Yu. I. Shanin

    2017-01-01

    Full Text Available The analytical review gives the basic concepts of the aero-optics problem arising from the radiation propagation in the region of the boundary layers of a laser installation carrier aircraft. Estimates the radiation wave front distortions at its propagation in the near and far field. Presents main calculation approaches and methods to solve the gas-dynamic and optical problems in propagating laser radiation. Conducts a detailed analysis of the flows and their generating optical aberrations introduced by the aircraft turret (a projection platform of the on-board laser. Considers the effect of various factors (shock wave, difference in wall and flow temperatures on the flow pattern and the optical aberrations. Provides research data on the aero-optics obtained in the flying laboratory directly while in flight. Briefly considers the experimental research methods, diagnostic equipment, and synthesis of results while studying the aero-optics problem. Discusses some methods for mitigating the aerodynamic effects on the light propagation under flight conditions. Presents data about the passive, active, and hybrid effects on the flow in the boundary layers in order to reduce aberrations through improving the flow aerodynamics.The paper considers operation of adaptive optical systems under conditions of aero-optical distortions. Presents the study results concerning the reduction of the aero-optics effect on the characteristics of radiation in far field. Gives some research results regarding the effect on the efficiency of the adaptive system of a laser beam jitter and a time delay in the feedback signal transmission, which occur under application conditions. Provides data on adaptive correction of aero-optical wave fronts of radiation. Considers some application aspects in control systems of the on-board adaptive optics of adaptive filtration as a way to improve the efficiency of adaptive optical systems. The project in mind is to use obtained results

  7. Adaptive optics in microscopy.

    Science.gov (United States)

    Booth, Martin J

    2007-12-15

    The imaging properties of optical microscopes are often compromised by aberrations that reduce image resolution and contrast. Adaptive optics technology has been employed in various systems to correct these aberrations and restore performance. This has required various departures from the traditional adaptive optics schemes that are used in astronomy. This review discusses the sources of aberrations, their effects and their correction with adaptive optics, particularly in confocal and two-photon microscopes. Different methods of wavefront sensing, indirect aberration measurement and aberration correction devices are discussed. Applications of adaptive optics in the related areas of optical data storage, optical tweezers and micro/nanofabrication are also reviewed.

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

    Science.gov (United States)

    Downie, John D.

    1990-01-01

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

  9. Fourier transform digital holographic adaptive optics imaging system

    Science.gov (United States)

    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

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

    Science.gov (United States)

    Downie, John D.; Goodman, Joseph W.

    1989-10-01

    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.

  11. An adaptive optics imaging system designed for clinical use

    Science.gov (United States)

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

    2015-01-01

    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

  12. [Adaptive optics for ophthalmology].

    Science.gov (United States)

    Saleh, M

    2016-04-01

    Adaptive optics is a technology enhancing the visual performance of an optical system by correcting its optical aberrations. Adaptive optics have already enabled several breakthroughs in the field of visual sciences, such as improvement of visual acuity in normal and diseased eyes beyond physiologic limits, and the correction of presbyopia. Adaptive optics technology also provides high-resolution, in vivo imaging of the retina that may eventually help to detect the onset of retinal conditions at an early stage and provide better assessment of treatment efficacy. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  13. Adaptive optics in ophthalmology

    Science.gov (United States)

    Iroshnikov, Nikita G.; Larichev, Andrey V.

    2006-09-01

    We present the experimental implementation of ophthalmic diagnostic systems with adaptive optics compensation of human eye aberration. The systems feature high speed operation and utilize deformable bimorph mirrors for wavefront correction. The results of aberration measurements and correction are discussed.

  14. Status of the ARGOS ground layer adaptive optics system

    Science.gov (United States)

    Gässler, Wolfgang; Rabien, Sebastian; Esposito, Simone; Lloyd-Hart, Michael; Barl, Lothar; Beckmann, Udo; Bluemchen, Thomas; Bonaglia, Marco; Borelli, José Luis; Brusa, Guido; Brynnel, Joar; Buschkamp, Peter; Busoni, Lorenzo; Carbonaro, Luca; Connot, Claus; Davies, Richard; Deysenroth, Matthias; Durney, Olivier; Green, Richard; Gemperlein, Hans; Gasho, Victor; Haug, Marcus; Hubbard, Pete; Ihle, Sebastian; Kulas, Martin; Lederer, Reinhard; Lewis, Jason; Loose, Christina; Lehmitz, Michael; Noenickx, Jamison; Nussbaum, Edmund; Orban de Xivry, Gilles; Peter, Diethard; Quirrenbach, Andreas; Rademacher, Matt; Raab, Walfried; Storm, Jesper; Schwab, Christian; Vaitheeswaran, Vidhya; Ziegleder, Julian

    2012-07-01

    ARGOS the Advanced Rayleigh guided Ground layer adaptive Optics System for the LBT (Large Binocular Telescope) is built by a German-Italian-American consortium. It will be a seeing reducer correcting the turbulence in the lower atmosphere over a field of 2' radius. In such way we expect to improve the spatial resolution over the seeing of about a factor of two and more and to increase the throughput for spectroscopy accordingly. In its initial implementation, ARGOS will feed the two near-infrared spectrograph and imager - LUCI I and LUCI II. The system consist of six Rayleigh lasers - three per eye of the LBT. The lasers are launched from the back of the adaptive secondary mirror of the LBT. ARGOS has one wavefront sensor unit per primary mirror of the LBT, each of the units with three Shack-Hartmann sensors, which are imaged on one detector. In 2010 and 2011, we already mounted parts of the instrument at the telescope to provide an environment for the main sub-systems. The commissioning of the instrument will start in 2012 in a staged approach. We will give an overview of ARGOS and its goals and report about the status and new challenges we encountered during the building phase. Finally we will give an outlook of the upcoming work, how we will operate it and further possibilities the system enables by design.

  15. Control code for laboratory adaptive optics teaching system

    Science.gov (United States)

    Jin, Moonseob; Luder, Ryan; Sanchez, Lucas; Hart, Michael

    2017-09-01

    By sensing and compensating wavefront aberration, adaptive optics (AO) systems have proven themselves crucial in large astronomical telescopes, retinal imaging, and holographic coherent imaging. Commercial AO systems for laboratory use are now available in the market. One such is the ThorLabs AO kit built around a Boston Micromachines deformable mirror. However, there are limitations in applying these systems to research and pedagogical projects since the software is written with limited flexibility. In this paper, we describe a MATLAB-based software suite to interface with the ThorLabs AO kit by using the MATLAB Engine API and Visual Studio. The software is designed to offer complete access to the wavefront sensor data, through the various levels of processing, to the command signals to the deformable mirror and fast steering mirror. In this way, through a MATLAB GUI, an operator can experiment with every aspect of the AO system's functioning. This is particularly valuable for tests of new control algorithms as well as to support student engagement in an academic environment. We plan to make the code freely available to the community.

  16. Design of an optimized adaptive optics system with a photo-controlled deformable mirror

    Czech Academy of Sciences Publication Activity Database

    Pilař, Jan; Bonora, Stefano; Lucianetti, Antonio; Jelínková, H.; Mocek, Tomáš

    2016-01-01

    Roč. 28, č. 13 (2016), s. 1422-1425 ISSN 1041-1135 Institutional support: RVO:68378271 Keywords : adaptive optics * closed loop systems * deformable mirror Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.375, year: 2016

  17. Solar Adaptive Optics

    Directory of Open Access Journals (Sweden)

    Thomas R. Rimmele

    2011-06-01

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

  18. Solar tomography adaptive optics.

    Science.gov (United States)

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

    2014-03-10

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

  19. Performance analysis of an adaptive optics system for free-space optics communication through atmospheric turbulence.

    Science.gov (United States)

    Wang, Yukun; Xu, Huanyu; Li, Dayu; Wang, Rui; Jin, Chengbin; Yin, Xianghui; Gao, Shijie; Mu, Quanquan; Xuan, Li; Cao, Zhaoliang

    2018-01-18

    The performance of free-space optics communication (FSOC) is greatly degraded by atmospheric turbulence. Adaptive optics (AO) is an effective method for attenuating the influence. In this paper, the influence of the spatial and temporal characteristics of turbulence on the performance of AO in a FSOC system is investigated. Based on the Greenwood frequency (GF) and the ratio of receiver aperture diameter to atmospheric coherent length (D/r 0 ), the relationship between FSOC performance (CE) and AO parameters (corrected Zernike modes number and bandwidth) is derived for the first time. Then, simulations and experiments are conducted to analyze the influence of AO parameters on FSOC performance under different GF and D/r 0 . The simulation and experimental results show that, for common turbulence conditions, the number of corrected Zernike modes can be fixed at 35 and the bandwidth of the AO system should be larger than the GF. Measurements of the bit error rate (BER) for moderate turbulence conditions (D/r 0  = 10, f G  = 60 Hz) show that when the bandwidth is two times that of GF, the average BER is decreased by two orders of magnitude compared with f G /f 3dB  = 1. These results and conclusions can provide important guidance in the design of an AO system for FSOC.

  20. Analysis technique for controlling system wavefront error with active/adaptive optics

    Science.gov (United States)

    Genberg, Victor L.; Michels, Gregory J.

    2017-08-01

    The ultimate goal of an active mirror system is to control system level wavefront error (WFE). In the past, the use of this technique was limited by the difficulty of obtaining a linear optics model. In this paper, an automated method for controlling system level WFE using a linear optics model is presented. An error estimate is included in the analysis output for both surface error disturbance fitting and actuator influence function fitting. To control adaptive optics, the technique has been extended to write system WFE in state space matrix form. The technique is demonstrated by example with SigFit, a commercially available tool integrating mechanical analysis with optical analysis.

  1. Development of a Low-order Adaptive Optics System at Udaipur ...

    Indian Academy of Sciences (India)

    Abstract. A low-order Adaptive Optics (AO) system is being develo- ped at the Udaipur Solar Observatory and we present in this paper the status of the project, which includes the image stabilization system and calibration of wavefront sensor and deformable mirror. The image stabi- lization system comprises of a piezo ...

  2. Science with Adaptive Optics

    CERN Document Server

    Brandner, Wolfgang; ESO Workshop

    2005-01-01

    The field of Adaptive Optics (AO) for astronomy has matured in recent years, and diffraction-limited image resolution in the near-infrared is now routinely achieved by ground-based 8 to 10m class telescopes. This book presents the proceedings of the ESO Workshop on Science with Adaptive Optics held in the fall of 2003. The book provides an overview on AO instrumentation, data acquisition and reduction strategies, and covers observations of the sun, solar system objects, circumstellar disks, substellar companions, HII regions, starburst environments, late-type stars, the galactic center, active galaxies, and quasars. The contributions present a vivid picture of the multitude of science topics being addressed by AO in observational astronomy.

  3. Comparative Study of Neural Network Frameworks for the Next Generation of Adaptive Optics Systems.

    Science.gov (United States)

    González-Gutiérrez, Carlos; Santos, Jesús Daniel; Martínez-Zarzuela, Mario; Basden, Alistair G; Osborn, James; Díaz-Pernas, Francisco Javier; De Cos Juez, Francisco Javier

    2017-06-02

    Many of the next generation of adaptive optics systems on large and extremely large telescopes require tomographic techniques in order to correct for atmospheric turbulence over a large field of view. Multi-object adaptive optics is one such technique. In this paper, different implementations of a tomographic reconstructor based on a machine learning architecture named "CARMEN" are presented. Basic concepts of adaptive optics are introduced first, with a short explanation of three different control systems used on real telescopes and the sensors utilised. The operation of the reconstructor, along with the three neural network frameworks used, and the developed CUDA code are detailed. Changes to the size of the reconstructor influence the training and execution time of the neural network. The native CUDA code turns out to be the best choice for all the systems, although some of the other frameworks offer good performance under certain circumstances.

  4. Underwater wireless optical MIMO system with spatial modulation and adaptive power allocation

    Science.gov (United States)

    Huang, Aiping; Tao, Linwei; Niu, Yilong

    2018-04-01

    In this paper, we investigate the performance of underwater wireless optical multiple-input multiple-output communication system combining spatial modulation (SM-UOMIMO) with flag dual amplitude pulse position modulation (FDAPPM). Channel impulse response for coastal and harbor ocean water links are obtained by Monte Carlo (MC) simulation. Moreover, we obtain the closed-form and upper bound average bit error rate (BER) expressions for receiver diversity including optical combining, equal gain combining and selected combining. And a novel adaptive power allocation algorithm (PAA) is proposed to minimize the average BER of SM-UOMIMO system. Our numeric results indicate an excellent match between the analytical results and numerical simulations, which confirms the accuracy of our derived expressions. Furthermore, the results show that adaptive PAA outperforms conventional fixed factor PAA and equal PAA obviously. Multiple-input single-output system with adaptive PAA obtains even better BER performance than MIMO one, at the same time reducing receiver complexity effectively.

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

    Science.gov (United States)

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

    2003-05-01

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

  6. A self-adaptive and nonmechanical motion autofocusing system for optical microscopes.

    Science.gov (United States)

    Qu, Yufu; Zhu, Shenyu; Zhang, Ping

    2016-11-01

    For the design of a passive autofocusing (AF) system for optical microscopes, many time-consuming and tedious experiments have been performed to determine and design a better focus criterion function, owing to the sample-dependence of this function. To accelerate the development of the AF systems in optical microscopes and to increase AF speed as well as maintain the AF accuracy, this study proposes a self-adaptive and nonmechanical motion AF system. The presented AF system does not require the selection and design of a focus criterion function when it is developed. Instead, the system can automatically determine a better focus criterion function for an observed sample by analyzing the texture features of the sample and subsequently perform an AF procedure to bring the sample into focus in the objective of an optical microscope. In addition, to increase the AF speed, the Z axis scanning of the mechanical motion of the sample or the objective is replaced by focusing scanning performed by a liquid lens, which is driven by an electrical current and does not involve mechanical motion. Experiments show that the reproducibility of the results obtained with the proposed self-adaptive and nonmechanical motion AF system is better than that provided by that of traditional AF systems, and that the AF speed is 10 times faster than that of traditional AF systems. Also, the self-adaptive function increased the speed of AF process by an average of 10.5% than Laplacian and Tenegrad functions. © 2016 Wiley Periodicals, Inc.

  7. Adaptive optics photoacoustic microscopy.

    Science.gov (United States)

    Jiang, Minshan; Zhang, Xiangyang; Puliafito, Carmen A; Zhang, Hao F; Jiao, Shuliang

    2010-10-11

    We have developed an adaptive optics photoacoustic microscope (AO-PAM) for high-resolution imaging of biological tissues, especially the retina. To demonstrate the feasibility of AO-PAM we first designed the AO system to correct the wavefront errors of the illuminating light of PAM. The aberrations of the optical system delivering the illuminating light to the sample in PAM was corrected with a close-loop AO system consisting of a 141-element MEMS-based deformable mirror (DM) and a Shack-Hartmann (SH) wavefront sensor operating at 15 Hz. The photoacoustic signal induced by the illuminating laser beam was detected by a custom-built needle ultrasonic transducer. When the wavefront errors were corrected by the AO system, the lateral resolution of PAM was measured to be better than 2.5 µm using a low NA objective lens. We tested the system on imaging ex vivo ocular samples, e.g., the ciliary body and retinal pigment epithelium (RPE) of a pig eye. The AO-PAM images showed significant quality improvement. For the first time we were able to resolve single RPE cells with PAM.

  8. Accuracies Of Optical Processors For Adaptive Optics

    Science.gov (United States)

    Downie, John D.; Goodman, Joseph W.

    1992-01-01

    Paper presents analysis of accuracies and requirements concerning accuracies of optical linear-algebra processors (OLAP's) in adaptive-optics imaging systems. Much faster than digital electronic processor and eliminate some residual distortion. Question whether errors introduced by analog processing of OLAP overcome advantage of greater speed. Paper addresses issue by presenting estimate of accuracy required in general OLAP that yields smaller average residual aberration of wave front than digital electronic processor computing at given speed.

  9. Modulation transfer function estimation of optical lens system by adaptive neuro-fuzzy methodology

    Science.gov (United States)

    Petković, Dalibor; Shamshirband, Shahaboddin; Pavlović, Nenad T.; Anuar, Nor Badrul; Kiah, Miss Laiha Mat

    2014-07-01

    The quantitative assessment of image quality is an important consideration in any type of imaging system. The modulation transfer function (MTF) is a graphical description of the sharpness and contrast of an imaging system or of its individual components. The MTF is also known and spatial frequency response. The MTF curve has different meanings according to the corresponding frequency. The MTF of an optical system specifies the contrast transmitted by the system as a function of image size, and is determined by the inherent optical properties of the system. In this study, the adaptive neuro-fuzzy (ANFIS) estimator is designed and adapted to estimate MTF value of the actual optical system. Neural network in ANFIS adjusts parameters of membership function in the fuzzy logic of the fuzzy inference system. The back propagation learning algorithm is used for training this network. This intelligent estimator is implemented using Matlab/Simulink and the performances are investigated. The simulation results presented in this paper show the effectiveness of the developed method.

  10. On distributed wavefront reconstruction for large-scale adaptive optics systems.

    Science.gov (United States)

    de Visser, Cornelis C; Brunner, Elisabeth; Verhaegen, Michel

    2016-05-01

    The distributed-spline-based aberration reconstruction (D-SABRE) method is proposed for distributed wavefront reconstruction with applications to large-scale adaptive optics systems. D-SABRE decomposes the wavefront sensor domain into any number of partitions and solves a local wavefront reconstruction problem on each partition using multivariate splines. D-SABRE accuracy is within 1% of a global approach with a speedup that scales quadratically with the number of partitions. The D-SABRE is compared to the distributed cumulative reconstruction (CuRe-D) method in open-loop and closed-loop simulations using the YAO adaptive optics simulation tool. D-SABRE accuracy exceeds CuRe-D for low levels of decomposition, and D-SABRE proved to be more robust to variations in the loop gain.

  11. Shack-Hartmann wavefront-sensor-based adaptive optics system for multiphoton microscopy.

    Science.gov (United States)

    Cha, Jae Won; Ballesta, Jerome; So, Peter T C

    2010-01-01

    The imaging depth of two-photon excitation fluorescence microscopy is partly limited by the inhomogeneity of the refractive index in biological specimens. This inhomogeneity results in a distortion of the wavefront of the excitation light. This wavefront distortion results in image resolution degradation and lower signal level. Using an adaptive optics system consisting of a Shack-Hartmann wavefront sensor and a deformable mirror, wavefront distortion can be measured and corrected. With adaptive optics compensation, we demonstrate that the resolution and signal level can be better preserved at greater imaging depth in a variety of ex-vivo tissue specimens including mouse tongue muscle, heart muscle, and brain. However, for these highly scattering tissues, we find signal degradation due to scattering to be a more dominant factor than aberration.

  12. Linear-quadratic-Gaussian control for adaptive optics systems using a hybrid model.

    Science.gov (United States)

    Looze, Douglas P

    2009-01-01

    This paper presents a linear-quadratic-Gaussian (LQG) design based on the equivalent discrete-time model of an adaptive optics (AO) system. The design model incorporates deformable mirror dynamics, an asynchronous wavefront sensor and zero-order hold operation, and a continuous-time model of the incident wavefront. Using the structure of the discrete-time model, the dimensions of the Riccati equations to be solved are reduced. The LQG controller is shown to improve AO system performance under several conditions.

  13. Testing and integrating the laser system of ARGOS: the ground layer adaptive optics for LBT

    Science.gov (United States)

    Loose, C.; Rabien, S.; Barl, L.; Borelli, J.; Deysenroth, M.; Gaessler, W.; Gemperlein, H.; Honsberg, M.; Kulas, M.; Lederer, R.; Raab, W.; Rahmer, G.; Ziegleder, J.

    2012-07-01

    The Laser Guide Star facility ARGOS will provide Ground Layer Adaptive Optics to the Large Binocular Telescope (LBT). The system operates three pulsed laser beacons above each of the two primary mirrors, which are Rayleigh scattered in 12km height. This enables correction over a wide field of view, using the adaptive secondary mirror of the LBT. The ARGOS laser system is designed around commercially available, pulsed Nd:YAG lasers working at 532 nm. In preparation for a successful commissioning, it is important to ascertain that the specifications are met for every component of the laser system. The testing of assembled, optical subsystems is likewise necessary. In particular it is required to confirm a high output power, beam quality and pulse stability of the beacons. In a second step, the integrated laser system along with its electronic cabinets are installed on a telescope simulator. This unit is capable of carrying the whole assembly and can be tilted to imitate working conditions at the LBT. It allows alignment and functionality testing of the entire system, ensuring that flexure compensation and system diagnosis work properly in different orientations.

  14. Immature visual neural system in children reflected by contrast sensitivity with adaptive optics correction

    Science.gov (United States)

    Liu, Rong; Zhou, Jiawei; Zhao, Haoxin; Dai, Yun; Zhang, Yudong; Tang, Yong; Zhou, Yifeng

    2014-01-01

    This study aimed to explore the neural development status of the visual system of children (around 8 years old) using contrast sensitivity. We achieved this by eliminating the influence of higher order aberrations (HOAs) with adaptive optics correction. We measured HOAs, modulation transfer functions (MTFs) and contrast sensitivity functions (CSFs) of six children and five adults with both corrected and uncorrected HOAs. We found that when HOAs were corrected, children and adults both showed improvements in MTF and CSF. However, the CSF of children was still lower than the adult level, indicating the difference in contrast sensitivity between groups cannot be explained by differences in optical factors. Further study showed that the difference between the groups also could not be explained by differences in non-visual factors. With these results we concluded that the neural systems underlying vision in children of around 8 years old are still immature in contrast sensitivity. PMID:24732728

  15. An Adaptive Damping Network Designed for Strapdown Fiber Optic Gyrocompass System for Ships

    Directory of Open Access Journals (Sweden)

    Jin Sun

    2017-03-01

    Full Text Available The strapdown fiber optic gyrocompass (strapdown FOGC system for ships primarily works on external horizontal damping and undamping statuses. When there are large sea condition changes, the system will switch frequently between the external horizontal damping status and the undamping status. This means that the system is always in an adjustment status and influences the dynamic accuracy of the system. Aiming at the limitations of the conventional damping method, a new design idea is proposed, where the adaptive control method is used to design the horizontal damping network of the strapdown FOGC system. According to the size of acceleration, the parameters of the damping network are changed to make the system error caused by the ship’s maneuvering to a minimum. Furthermore, the jump in damping coefficient was transformed into gradual change to make a smooth system status switch. The adaptive damping network was applied for strapdown FOGC under the static and dynamic condition, and its performance was compared with the conventional damping, and undamping means. Experimental results showed that the adaptive damping network was effective in improving the dynamic performance of the strapdown FOGC.

  16. Towards an automatic wind speed and direction profiler for Wide Field adaptive optics systems

    Science.gov (United States)

    Sivo, G.; Turchi, A.; Masciadri, E.; Guesalaga, A.; Neichel, B.

    2018-05-01

    Wide Field Adaptive Optics (WFAO) systems are among the most sophisticated adaptive optics (AO) systems available today on large telescopes. Knowledge of the vertical spatio-temporal distribution of wind speed (WS) and direction (WD) is fundamental to optimize the performance of such systems. Previous studies already proved that the Gemini Multi-Conjugated AO system (GeMS) is able to retrieve measurements of the WS and WD stratification using the SLOpe Detection And Ranging (SLODAR) technique and to store measurements in the telemetry data. In order to assess the reliability of these estimates and of the SLODAR technique applied to such complex AO systems, in this study we compared WS and WD values retrieved from GeMS with those obtained with the atmospheric model Meso-NH on a rich statistical sample of nights. It has previously been proved that the latter technique provided excellent agreement with a large sample of radiosoundings, both in statistical terms and on individual flights. It can be considered, therefore, as an independent reference. The excellent agreement between GeMS measurements and the model that we find in this study proves the robustness of the SLODAR approach. To bypass the complex procedures necessary to achieve automatic measurements of the wind with GeMS, we propose a simple automatic method to monitor nightly WS and WD using Meso-NH model estimates. Such a method can be applied to whatever present or new-generation facilities are supported by WFAO systems. The interest of this study is, therefore, well beyond the optimization of GeMS performance.

  17. Adaptive Optical Scanning Holography

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2012-07-01

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

  19. Removing damped sinusoidal vibrations in adaptive optics systems using a DFT-based estimation method

    Science.gov (United States)

    Kania, Dariusz

    2017-06-01

    The problem of a vibrations rejection in adaptive optics systems is still present in publications. These undesirable signals emerge because of shaking the system structure, the tracking process, etc., and they usually are damped sinusoidal signals. There are some mechanical solutions to reduce the signals but they are not very effective. One of software solutions are very popular adaptive methods. An AVC (Adaptive Vibration Cancellation) method has been presented and developed in recent years. The method is based on the estimation of three vibrations parameters and values of frequency, amplitude and phase are essential to produce and adjust a proper signal to reduce or eliminate vibrations signals. This paper presents a fast (below 10 ms) and accurate estimation method of frequency, amplitude and phase of a multifrequency signal that can be used in the AVC method to increase the AO system performance. The method accuracy depends on several parameters: CiR - number of signal periods in a measurement window, N - number of samples in the FFT procedure, H - time window order, SNR, THD, b - number of A/D converter bits in a real time system, γ - the damping ratio of the tested signal, φ - the phase of the tested signal. Systematic errors increase when N, CiR, H decrease and when γ increases. The value of systematic error for γ = 0.1%, CiR = 1.1 and N = 32 is approximately 10^-4 Hz/Hz. This paper focuses on systematic errors of and effect of the signal phase and values of γ on the results.

  20. Multigrid approach to predictive wave-front reconstruction in adaptive optical systems.

    Science.gov (United States)

    Barchers, Jeffrey D

    2004-06-20

    A computationally efficient approach, based on the principles of multigrid methods, to predictive wave-front reconstruction in adaptive optical systems is described. Local predictive estimators are computed by use of recursive least squares on multiple grids. Each grid is increasingly coarse, allowing for temporal prediction of the behavior of both high- and low-spatial-frequency aberrations. Example numerical simulation results are given, showing that implementing the recursive least-squares algorithm for predictive estimation in a multigrid fashion greatly accelerates convergence to the steady-state optimal estimator condition. By implementation of the multigrid predictive reconstructor in parallel, the computational cost of implementing a predictive wave-front reconstruction scheme that uses recursive least squares for each processor at each cycle can be reduced from [symbol: see text](m2) to [symbol: see text](2m), where m is the number of actuators.

  1. A high speed model-based approach for wavefront sensorless adaptive optics systems

    Science.gov (United States)

    Lianghua, Wen; Yang, Ping; Shuai, Wang; Wenjing, Liu; Shanqiu, Chen; Xu, Bing

    2018-02-01

    To improve temporal-frequency property of wavefront sensorless adaptive optics (AO) systems, a fast general model-based aberration correction algorithm is presented. The fast general model-based approach is based on the approximately linear relation between the mean square of the aberration gradients and the second moment of far-field intensity distribution. The presented model-based method is capable of completing a mode aberration effective correction just applying one disturbing onto the deformable mirror(one correction by one disturbing), which is reconstructed by the singular value decomposing the correlation matrix of the Zernike functions' gradients. Numerical simulations of AO corrections under the various random and dynamic aberrations are implemented. The simulation results indicate that the equivalent control bandwidth is 2-3 times than that of the previous method with one aberration correction after applying N times disturbing onto the deformable mirror (one correction by N disturbing).

  2. Static and predictive tomographic reconstruction for wide-field multi-object adaptive optics systems.

    Science.gov (United States)

    Correia, C; Jackson, K; Véran, J-P; Andersen, D; Lardière, O; Bradley, C

    2014-01-01

    Multi-object adaptive optics (MOAO) systems are still in their infancy: their complex optical designs for tomographic, wide-field wavefront sensing, coupled with open-loop (OL) correction, make their calibration a challenge. The correction of a discrete number of specific directions in the field allows for streamlined application of a general class of spatio-angular algorithms, initially proposed in Whiteley et al. [J. Opt. Soc. Am. A15, 2097 (1998)], which is compatible with partial on-line calibration. The recent Learn & Apply algorithm from Vidal et al. [J. Opt. Soc. Am. A27, A253 (2010)] can then be reinterpreted in a broader framework of tomographic algorithms and is shown to be a special case that exploits the particulars of OL and aperture-plane phase conjugation. An extension to embed a temporal prediction step to tackle sky-coverage limitations is discussed. The trade-off between lengthening the camera integration period, therefore increasing system lag error, and the resulting improvement in SNR can be shifted to higher guide-star magnitudes by introducing temporal prediction. The derivation of the optimal predictor and a comparison to suboptimal autoregressive models is provided using temporal structure functions. It is shown using end-to-end simulations of Raven, the MOAO science, and technology demonstrator for the 8 m Subaru telescope that prediction allows by itself the use of 1-magnitude-fainter guide stars.

  3. Errors in the estimation method for the rejection of vibrations in adaptive optics systems

    Science.gov (United States)

    Kania, Dariusz

    2017-06-01

    In recent years the problem of the mechanical vibrations impact in adaptive optics (AO) systems has been renewed. These signals are damped sinusoidal signals and have deleterious effect on the system. One of software solutions to reject the vibrations is an adaptive method called AVC (Adaptive Vibration Cancellation) where the procedure has three steps: estimation of perturbation parameters, estimation of the frequency response of the plant, update the reference signal to reject/minimalize the vibration. In the first step a very important problem is the estimation method. A very accurate and fast (below 10 ms) estimation method of these three parameters has been presented in several publications in recent years. The method is based on using the spectrum interpolation and MSD time windows and it can be used to estimate multifrequency signals. In this paper the estimation method is used in the AVC method to increase the system performance. There are several parameters that affect the accuracy of obtained results, e.g. CiR - number of signal periods in a measurement window, N - number of samples in the FFT procedure, H - time window order, SNR, b - number of ADC bits, γ - damping ratio of the tested signal. Systematic errors increase when N, CiR, H decrease and when γ increases. The value for systematic error is approximately 10^-10 Hz/Hz for N = 2048 and CiR = 0.1. This paper presents equations that can used to estimate maximum systematic errors for given values of H, CiR and N before the start of the estimation process.

  4. A High-resolution Multi-wavelength Simultaneous Imaging System with Solar Adaptive Optics

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Changhui; Zhu, Lei; Gu, Naiting; Rao, Xuejun; Zhang, Lanqiang; Bao, Hua; Kong, Lin; Guo, Youming; Zhong, Libo; Ma, Xue’an; Li, Mei; Wang, Cheng; Zhang, Xiaojun; Fan, Xinlong; Chen, Donghong; Feng, Zhongyi; Wang, Xiaoyun; Wang, Zhiyong, E-mail: gunaiting@ioe.ac.cn [The Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, P.O. Box 350, Shuangliu, Chengdu 610209, Sichuan (China)

    2017-10-01

    A high-resolution multi-wavelength simultaneous imaging system from visible to near-infrared bands with a solar adaptive optics system, in which seven imaging channels, including the G band (430.5 nm), the Na i line (589 nm), the H α line (656.3 nm), the TiO band (705.7 nm), the Ca ii IR line (854.2 nm), the He i line (1083 nm), and the Fe i line (1565.3 nm), are chosen, is developed to image the solar atmosphere from the photosphere layer to the chromosphere layer. To our knowledge, this is the solar high-resolution imaging system with the widest spectral coverage. This system was demonstrated at the 1 m New Vaccum Solar Telescope and the on-sky high-resolution observational results were acquired. In this paper, we will illustrate the design and performance of the imaging system. The calibration and the data reduction of the system are also presented.

  5. Performance Comparison of Wavefront-Sensorless Adaptive Optics Systems by Using of the Focal Plane

    Directory of Open Access Journals (Sweden)

    Huizhen Yang

    2015-01-01

    Full Text Available The correction capability and the convergence speed of the wavefront-sensorless adaptive optics (AO system are compared based on two different system control algorithms, which both use the information of focal plane. The first algorithm is designed through the linear relationship between the second moment of the aberration gradients and the masked far-field intensity distribution and the second is stochastic parallel gradient descent (SPGD, which is the most commonly used algorithm in wavefront-sensorless AO systems. A wavefront-sensorless AO model is established with a 61-element deformable mirror (DM and a CCD. Performance of the two control algorithms is investigated and compared through correcting different wavefront aberrations. Results show that the correction ability of AO system based on the proposed control algorithm is obviously better than that of AO system based on SPGD algorithm when the wavefront aberrations increase. The time needed by the proposed control algorithm is much less than that of SPGD when the AO system achieves similar correction results. Additionally, the convergence speed of the proposed control algorithm is independent of the turbulence strength while the number of intensity measurements needed by SPGD increases as the turbulence strength magnifies.

  6. Optical Communication System for Remote Monitoring and Adaptive Control of Distributed Ground Sensors Exhibiting Collective Intelligence

    Energy Technology Data Exchange (ETDEWEB)

    Cameron, S.M.; Stantz, K.M.; Trahan, M.W.; Wagner, J.S.

    1998-11-01

    Comprehensive management of the battle-space has created new requirements in information management, communication, and interoperability as they effect surveillance and situational awareness. The objective of this proposal is to expand intelligent controls theory to produce a uniquely powerful implementation of distributed ground-based measurement incorporating both local collective behavior, and interoperative global optimization for sensor fusion and mission oversight. By using a layered hierarchal control architecture to orchestrate adaptive reconfiguration of autonomous robotic agents, we can improve overall robustness and functionality in dynamic tactical environments without information bottlenecks. In this concept, each sensor is equipped with a miniaturized optical reflectance modulator which is interactively monitored as a remote transponder using a covert laser communication protocol from a remote mothership or operative. Robot data-sharing at the ground level can be leveraged with global evaluation criteria, including terrain overlays and remote imaging data. Information sharing and distributed intelli- gence opens up a new class of remote-sensing applications in which small single-function autono- mous observers at the local level can collectively optimize and measure large scale ground-level signals. AS the need for coverage and the number of agents grows to improve spatial resolution, cooperative behavior orchestrated by a global situational awareness umbrella will be an essential ingredient to offset increasing bandwidth requirements within the net. A system of the type described in this proposal will be capable of sensitively detecting, tracking, and mapping spatial distributions of measurement signatures which are non-stationary or obscured by clutter and inter- fering obstacles by virtue of adaptive reconfiguration. This methodology could be used, for example, to field an adaptive ground-penetrating radar for detection of underground structures in

  7. The ARGOS laser system: green light for ground layer adaptive optics at the LBT

    Science.gov (United States)

    Raab, Walfried; Rabien, Sebastian; Gässler, Wolfgang; Esposito, Simone; Barl, Lothar; Borelli, Jose; Daysenroth, Matthias; Gemperlein, Hans; Kulas, Martin; Ziegleder, Julian

    2014-07-01

    We report on the development of the laser system of ARGOS, the multiple laser guide star adaptive optics system for the Large Binocular Telescope (LBT). The system uses a total of six high powered, pulsed Nd:YAG lasers frequency-doubled to a wavelength of 532 nm to generate a set of three guide stars above each of the LBT telescopes. The position of each of the LGS constellations on sky as well as the relative position of the individual laser guide stars within this constellation is controlled by a set of steerable mirrors and a fast tip-tilt mirror within the laser system. The entire opto-mechanical system is housed in two hermetically sealed and thermally controlled enclosures on the SX and DX side of the LBT telescope. The laser beams are propagated through two refractive launch telescopes which focus the beams at an altitude of 12 km, creating a constellation of laser guide stars around a 4 arcminute diameter circle by means of Rayleigh scattering. In addition to the GLAO Rayleigh beacon system, ARGOS has also been designed for a possible future upgrade with a hybrid sodium laser - Rayleigh beacon combination, enabling diffraction limited operation. The ARGOS laser system was successfully installed at the LBT in April 2013. Extensive functional tests have been carried out and have verified the operation of the systems according to specifications. The alignment of the laser system with respect to the launch telescope was carried out during two more runs in June and October 2013, followed by the first propagation of laser light on sky in November 2013.

  8. Simulated human eye retina adaptive optics imaging system based on a liquid crystal on silicon device

    International Nuclear Information System (INIS)

    Jiang Baoguang; Cao Zhaoliang; Mu Quanquan; Hu Lifa; Li Chao; Xuan Li

    2008-01-01

    In order to obtain a clear image of the retina of model eye, an adaptive optics system used to correct the wave-front error is introduced in this paper. The spatial light modulator that we use here is a liquid crystal on a silicon device instead of a conversional deformable mirror. A paper with carbon granule is used to simulate the retina of human eye. The pupil size of the model eye is adjustable (3-7 mm). A Shack–Hartman wave-front sensor is used to detect the wave-front aberration. With this construction, a value of peak-to-valley is achieved to be 0.086 λ, where λ is wavelength. The modulation transfer functions before and after corrections are compared. And the resolution of this system after correction (691p/m) is very close to the dirraction limit resolution. The carbon granule on the white paper which has a size of 4.7 μm is seen clearly. The size of the retina cell is between 4 and 10 mu;m. So this system has an ability to image the human eye's retina. (classical areas of phenomenology)

  9. Atmospheric free-space coherent optical communications with adaptive optics

    Science.gov (United States)

    Ting, Chueh; Zhang, Chengyu; Yang, Zikai

    2017-02-01

    Free-space coherent optical communications have a potential application to offer last mile bottleneck solution in future local area networks (LAN) because of their information carrier, information security and license-free status. Coherent optical communication systems using orthogonal frequency division multiplexing (OFDM) digital modulation are successfully demonstrated in a long-haul tens Giga bits via optical fiber, but they are not yet available in free space due to atmospheric turbulence-induced channel fading. Adaptive optics is recognized as a promising technology to mitigate the effects of atmospheric turbulence in free-space optics. In this paper, a free-space coherent optical communication system using an OFDM digital modulation scheme and adaptive optics (FSO OFDM AO) is proposed, a Gamma-Gamma distribution statistical channel fading model for the FSO OFDM AO system is examined, and FSO OFDM AO system performance is evaluated in terms of bit error rate (BER) versus various propagation distances.

  10. ℋ2-optimal control of an adaptive optics system. Pt.I: data-driven modeling of the wavefront disturbance

    NARCIS (Netherlands)

    Hinnen, K.J.G.; Verhaegen, M.; Doelman, N.J.

    2005-01-01

    Even though the wavefront distortion introduced by atmospheric turbulence is a dynamic process, its temporal evolution is usually neglected in the adaptive optics (AO) control design. Most AO control systems consider only the spatial correlation in a separate wavefront reconstruction step. By

  11. The main postulates of adaptive correction of distortions of the wave front in large-size optical systems

    Directory of Open Access Journals (Sweden)

    V. V. Sychev

    2014-01-01

    Full Text Available In the development of optical telescopes, striving to increase the penetrating power of a telescope has been always the main trend. A real way to solve this problem is to raise the quality of the image (reduction of the image angular size under real conditions of distorting factor and increase a diameter of the main mirror. This is counteracted by the various distorting factors or interference occurring in realtime use of telescopes, as well as by complicated manufacturing processes of large mirrors.It is shown that the most effective method to deal with the influence of distorting factors on the image quality in the telescope is the minimization (through selecting the place to mount a telescope and choosing the rational optical scheme, creating materials and new technologies, improving a design, unloading the mirrors, mounting choice, etc., and then the adaptive compensation of remaining distortions.It should be noted that a domestic concept to design large-sized telescopes allows us to use, in our opinion, the most efficient ways to do this. It means to abandon the creation of "an absolutely rigid and well-ordered" design, providing the passively aligned state telescope optics under operating conditions. The design must just have such a level of residual deformations that their effect can be efficiently compensated by the adaptive system using the segmented elements of the primary mirror and the secondary mirror as a corrector.It has been found that in the transmission optical systems to deliver laser power to a remote object, it is necessary not only to overcome the distorting effect of factors inherent in optical information systems, but, additionally, find a way to overcome a number of new difficulties. The main ones have been identified to be as follows:• the influence of laser radiation on the structure components and the propagation medium and, as a consequence, the opposite effect of the structure components and the propagation

  12. Rapid and highly integrated FPGA-based Shack-Hartmann wavefront sensor for adaptive optics system

    Science.gov (United States)

    Chen, Yi-Pin; Chang, Chia-Yuan; Chen, Shean-Jen

    2018-02-01

    In this study, a field programmable gate array (FPGA)-based Shack-Hartmann wavefront sensor (SHWS) programmed on LabVIEW can be highly integrated into customized applications such as adaptive optics system (AOS) for performing real-time wavefront measurement. Further, a Camera Link frame grabber embedded with FPGA is adopted to enhance the sensor speed reacting to variation considering its advantage of the highest data transmission bandwidth. Instead of waiting for a frame image to be captured by the FPGA, the Shack-Hartmann algorithm are implemented in parallel processing blocks design and let the image data transmission synchronize with the wavefront reconstruction. On the other hand, we design a mechanism to control the deformable mirror in the same FPGA and verify the Shack-Hartmann sensor speed by controlling the frequency of the deformable mirror dynamic surface deformation. Currently, this FPGAbead SHWS design can achieve a 266 Hz cyclic speed limited by the camera frame rate as well as leaves 40% logic slices for additionally flexible design.

  13. Hybrid diversity method utilizing adaptive diversity function for recovering unknown aberrations in an optical system

    Science.gov (United States)

    Dean, Bruce H. (Inventor)

    2009-01-01

    A method of recovering unknown aberrations in an optical system includes collecting intensity data produced by the optical system, generating an initial estimate of a phase of the optical system, iteratively performing a phase retrieval on the intensity data to generate a phase estimate using an initial diversity function corresponding to the intensity data, generating a phase map from the phase retrieval phase estimate, decomposing the phase map to generate a decomposition vector, generating an updated diversity function by combining the initial diversity function with the decomposition vector, generating an updated estimate of the phase of the optical system by removing the initial diversity function from the phase map. The method may further include repeating the process beginning with iteratively performing a phase retrieval on the intensity data using the updated estimate of the phase of the optical system in place of the initial estimate of the phase of the optical system, and using the updated diversity function in place of the initial diversity function, until a predetermined convergence is achieved.

  14. Adaptive optics in digital micromirror based confocal microscopy

    OpenAIRE

    Pozzi, P.; Wilding, D.; Soloviev, O.A.; Vdovine, Gleb; Verhaegen, M.H.G.; Bifano, Thomas G.; Kubby, Joel; Gigan, Sylvain

    2016-01-01

    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 senso...

  15. Adaptive optics in digital micromirror based confocal microscopy

    NARCIS (Netherlands)

    Pozzi, P.; Wilding, D.; Soloviev, O.A.; Vdovine, Gleb; Verhaegen, M.H.G.; Bifano, Thomas G.; Kubby, Joel; Gigan, Sylvain

    2016-01-01

    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

  16. A correction algorithm to simultaneously control dual deformable mirrors in a woofer-tweeter adaptive optics system

    Science.gov (United States)

    Li, Chaohong; Sredar, Nripun; Ivers, Kevin M.; Queener, Hope; Porter, Jason

    2010-01-01

    We present a direct slope-based correction algorithm to simultaneously control two deformable mirrors (DMs) in a woofer-tweeter adaptive optics system. A global response matrix was derived from the response matrices of each deformable mirror and the voltages for both deformable mirrors were calculated simultaneously. This control algorithm was tested and compared with a 2-step sequential control method in five normal human eyes using an adaptive optics scanning laser ophthalmoscope. The mean residual total root-mean-square (RMS) wavefront errors across subjects after adaptive optics (AO) correction were 0.128 ± 0.025 μm and 0.107 ± 0.033 μm for simultaneous and 2-step control, respectively (7.75-mm pupil). The mean intensity of reflectance images acquired after AO convergence was slightly higher for 2-step control. Radially-averaged power spectra calculated from registered reflectance images were nearly identical for all subjects using simultaneous or 2-step control. The correction performance of our new simultaneous dual DM control algorithm is comparable to 2-step control, but is more efficient. This method can be applied to any woofer-tweeter AO system. PMID:20721058

  17. Adaptive elimination of optical fiber transmission noise in fiber ocean bottom seismic system

    Science.gov (United States)

    Zhong, Qiuwen; Hu, Zhengliang; Cao, Chunyan; Dong, Hongsheng

    2017-10-01

    In this paper, a pressure and acceleration insensitive reference Interferometer is used to obtain laser and public noise introduced by transmission fiber and laser. By using direct subtraction and adaptive filtering, this paper attempts to eliminate and estimation the transmission noise of sensing probe. This paper compares the noise suppression effect of four methods, including the direct subtraction (DS), the least mean square error adaptive elimination (LMS), the normalized least mean square error adaptive elimination (NLMS) and the least square (RLS) adaptive filtering. The experimental results show that the noise reduction effect of RLS and NLMS are almost the same, better than LMS and DS, which can reach 8dB (@100Hz). But considering the workload, RLS is not conducive to the real-time operating system. When it comes to the same treatment effect, the practicability of NLMS is higher than RLS. The noise reduction effect of LMS is slightly worse than that of RLS and NLMS, about 6dB (@100Hz), but its computational complexity is small, which is beneficial to the real time system implementation. It can also be seen that the DS method has the least amount of computational complexity, but the noise suppression effect is worse than that of the adaptive filter due to the difference of the noise amplitude between the RI and the SI, only 4dB (@100Hz) can be reached. The adaptive filter can basically eliminate the influence of the transmission noise, and the simulation signal of the sensor is kept intact.

  18. First exoplanet and disk results with the PALM-3000 adaptive optics system

    Science.gov (United States)

    Dekany, Richard; Burruss, Rick; Shelton, J. Chris; Oppenheimer, Ben; Vasisht, Gautam; Metchev, Stanimir; Roberts, Jennifer; Tesch, Jonathan; Truong, Tuan; Milburn, Jennifer; Hale, David; Baranec, Christoph; Hildebrandt, Sergi; Wahl, Matthew; Beichman, Chas; Hillenbrand, Lynne; Patel, Rahul; Hinkley, Sasha; Cady, Eric; Parry, Ian

    2013-12-01

    We describe the status of the PALM-3000 adaptive optics facility instrument for the Hale telescope at Palomar Observatory. Since first light in June 2011, PALM-3000 has made significant advances in both performance and sensitivity. Using Strehl ratio as our performance metric, we present results in 64x64 and 32x32 wavefront sensor pupil sampling modes on a range of guide stars from V ~ 3 to 12. We describe our automated reconstructor pipeline tool, which incorporates pupil illumination and an optimal-estimator Baysian approach which serve to boost faint guide star performance. We conclude by presenting initial high-contrast circumstellar disk results from the PHARO vector vortex coronagraph and exoplanet spectra from the P1640 integral field spectrograph.

  19. Free space optical communications utilizing MEMS adaptive optics correction

    Science.gov (United States)

    Thompson, Charles A.; Kartz, Michael W.; Flath, Laurence M.; Wilks, Scott C.; Young, Richard A.; Johnson, Gary W.; Ruggiero, Anthony J.

    2002-12-01

    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 especially aimed at corporate intranet and sporting event video. 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 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 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.

  20. Adaptive Optics for Industry and Medicine

    Science.gov (United States)

    Dainty, Christopher

    2008-01-01

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

  1. An H-band Vector Vortex Coronagraph for the Subaru Coronagraphic Extreme-adaptive Optics System

    Science.gov (United States)

    Kühn, J.; Serabyn, E.; Lozi, J.; Jovanovic, N.; Currie, T.; Guyon, O.; Kudo, T.; Martinache, F.; Liewer, K.; Singh, G.; Tamura, M.; Mawet, D.; Hagelberg, J.; Defrere, D.

    2018-03-01

    The vector vortex is a coronagraphic imaging mode of the recently commissioned Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) platform on the 8 m Subaru Telescope. This multi-purpose high-contrast visible and near-infrared (R- to K-band) instrument is not only intended to serve as a VLT-class “planet-imager” instrument in the northern hemisphere, but also to operate as a technology demonstration testbed ahead of the ELTs-era, with a particular emphasis on small inner-working angle (IWA) coronagraphic capabilities. The given priority to small-IWA imaging led to the early design choice to incorporate focal-plane phase-mask coronagraphs. In this context, a test H-band vector vortex liquid crystal polymer waveplate was provided to SCExAO, to allow a one-to-one comparison of different small-IWA techniques on the same telescope instrument, before considering further steps. Here we present a detailed overview of the vector vortex coronagraph, from its installation and performances on the SCExAO optical bench, to the on-sky results in the extreme AO regime, as of late 2016/early 2017. To this purpose, we also provide a few recent on-sky imaging examples, notably high-contrast ADI detection of the planetary-mass companion κ Andromedae b, with a signal-to-noise ratio above 100 reached in less than 10 mn exposure time.

  2. Detection of the dusty torus in AGN with COMIC, the new infrared camera dedicated to the ESO adaptive optics system.

    Science.gov (United States)

    Marco, Olivier

    1997-10-01

    High angular resolution observation has greatly benefitted from adaptive optic systems working in the infrared. The COMIC camera, the second camera dedicated to ADONIS, the ESO 3.60 meter telescope adaptive optics system, allows observation in the spectral range 3-5 micron at the diffraction limit of the telescope. The characterization of the camera at the Meudon and Grenoble laboratories, then its performances determination on the sky in Chile constitute the first part of this dissertation. A new method for evaluating the limiting magnitudes is proposed which takes into account the various contributions to the detectivity loss between laboratory testing and real condition observations. This approach can be transferred to any other case where a priori observing conditions are known ( Strehl ratio or seeing ). Study of the central region of Active Galactic Nuclei (~1 arcsec) requires high angular resolution. In particular, warm and hot dust is emissive in the 1-5 micron spectral region. Thus, adaptive optics observations are well suited to AGN observation. It is predicted that the central engine and its neighboring environment are embedded within an optically thin dusty/molecular torus which may, along some lines of sight, obscure and even fully hide the nuclear emission leading to distinct observational properties for objects supposed to be identical. Observations made with ADONIS & COMIC of NGC7469 and NGC1068 have shown large amounts of dust located in the torus but also mixed with gas from the narrow line emission region. The high angular resolution achieved has allowed the determination of the dust temperature, mass and spatial distribution around the AGN central engine. These results are in agreement with several torus models and could help to constrain them.

  3. Adaptive optics and laser guide stars at Lick observatory

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-11-15

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

  4. A Phonocardiographic-Based Fiber-Optic Sensor and Adaptive Filtering System for Noninvasive Continuous Fetal Heart Rate Monitoring

    Directory of Open Access Journals (Sweden)

    Radek Martinek

    2017-04-01

    Full Text Available This paper focuses on the design, realization, and verification of a novel phonocardiographic- based fiber-optic sensor and adaptive signal processing system for noninvasive continuous fetal heart rate (fHR monitoring. Our proposed system utilizes two Mach-Zehnder interferometeric sensors. Based on the analysis of real measurement data, we developed a simplified dynamic model for the generation and distribution of heart sounds throughout the human body. Building on this signal model, we then designed, implemented, and verified our adaptive signal processing system by implementing two stochastic gradient-based algorithms: the Least Mean Square Algorithm (LMS, and the Normalized Least Mean Square (NLMS Algorithm. With this system we were able to extract the fHR information from high quality fetal phonocardiograms (fPCGs, filtered from abdominal maternal phonocardiograms (mPCGs by performing fPCG signal peak detection. Common signal processing methods such as linear filtering, signal subtraction, and others could not be used for this purpose as fPCG and mPCG signals share overlapping frequency spectra. The performance of the adaptive system was evaluated by using both qualitative (gynecological studies and quantitative measures such as: Signal-to-Noise Ratio—SNR, Root Mean Square Error—RMSE, Sensitivity—S+, and Positive Predictive Value—PPV.

  5. Terahertz adaptive optics with a deformable mirror.

    Science.gov (United States)

    Brossard, Mathilde; Sauvage, Jean-François; Perrin, Mathias; Abraham, Emmanuel

    2018-04-01

    We report on the wavefront correction of a terahertz (THz) beam using adaptive optics, which requires both a wavefront sensor that is able to sense the optical aberrations, as well as a wavefront corrector. The wavefront sensor relies on a direct 2D electro-optic imaging system composed of a ZnTe crystal and a CMOS camera. By measuring the phase variation of the THz electric field in the crystal, we were able to minimize the geometrical aberrations of the beam, thanks to the action of a deformable mirror. This phase control will open the route to THz adaptive optics in order to optimize the THz beam quality for both practical and fundamental applications.

  6. High Resolution Observations using Adaptive Optics: Achievements ...

    Indian Academy of Sciences (India)

    Abstract. Over the last few years, several interesting observations were obtained with the help of solar Adaptive Optics (AO). In this paper, few observations made using the solar AO are enlightened and briefly discussed. A list of disadvantages with the current AO system are presented. With telescopes larger than 1.5m ...

  7. Adaptive Optics Metrics & QC Scheme

    Science.gov (United States)

    Girard, Julien H.

    2017-09-01

    "There are many Adaptive Optics (AO) fed instruments on Paranal and more to come. To monitor their performances and assess the quality of the scientific data, we have developed a scheme and a set of tools and metrics adapted to each flavour of AO and each data product. Our decisions to repeat observations or not depends heavily on this immediate quality control "zero" (QC0). Atmospheric parameters monitoring can also help predict performances . At the end of the chain, the user must be able to find the data that correspond to his/her needs. In Particular, we address the special case of SPHERE."

  8. Extreme Computing for Extreme Adaptive Optics: the Key to Finding Life Outside our Solar System

    KAUST Repository

    Ltaief, Hatem

    2018-01-01

    The real-time correction of telescopic images in the search for exoplanets is highly sensitive to atmospheric aberrations. The pseudo- inverse algorithm is an efficient mathematical method to filter out these turbulences. We introduce a new partial singular value decomposition (SVD) algorithm based on QR-based Diagonally Weighted Halley (QDWH) iteration for the pseudo-inverse method of adaptive optics. The QDWH partial SVD algorithm selectively calculates the most significant singular values and their corresponding singular vectors. We develop a high performance implementation and demonstrate the numerical robustness of the QDWH-based partial SVD method. We also perform a benchmarking campaign on various generations of GPU hardware accelerators and compare against the state-of-the-art SVD implementation SGESDD from the MAGMA library. Numerical accuracy and performance results are reported using synthetic and real observational datasets from the Subaru telescope. Our implementation outperforms SGESDD by up to fivefold and fourfold performance speedups on ill-conditioned synthetic matrices and real observational datasets, respectively. The pseudo-inverse simulation code will be deployed on-sky for the Subaru telescope during observation nights scheduled early 2018.

  9. Comparison of closed loop and sensorless adaptive optics in widefield optical microscopy.

    OpenAIRE

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

    2013-01-01

    We report on a closed loop widefield adaptive optics, optical microscopy system in which the feedback signal is provided by backscattered light from the sample acting as a guide star. The improvement in imaging performance is compared to an adaptive optics system controlled via an image optimisation routine commonly described as sensorless adaptive optics. The samples viewed were imaged without fluorescence to ensure that photobleaching and other potential variations did not affect the compar...

  10. An IIR adaptive electronic equalizer for polarization multiplexed fiber optic communication systems

    Science.gov (United States)

    Zeng, Xiang-Ye; Liu, Jian-Fei; Zhao, Qi-Da

    2011-09-01

    An electronic digital equalizer for polarization multiplex coherent fiber optic communication systems is designed to compensate polarization mode dispersion (PMD) and residual chromatic dispersion (CD) of transmission channel. The proposed equalizer is realized with fraction spaced infinite impulse response (IIR) butterfly structure with 21 feedforward taps and 2 feedback taps. Compared with finite impulse response (FIR) structure, this structure can reduce implementation complexity of hardware under the same condition. To keep track of the random variation of channel characteristics, the filter weights are updated by least mean square (LMS) algorithm. The simulation results show that the proposed equalizer can compensate residual chromatic dispersion (CD) of 1600 ps/nm and differential group delay (DGD) of 90 ps simultaneously, and also can increase the PMD and residual CD tolerance of the whole communication system.

  11. Design and optimization of an adaptive optics system for a high-average-power multi-slab laser (HiLASE).

    Science.gov (United States)

    Pilar, Jan; Slezak, Ondrej; Sikocinski, Pawel; Divoky, Martin; Sawicka, Magdalena; Bonora, Stefano; Lucianetti, Antonio; Mocek, Tomas; Jelinkova, Helena

    2014-05-20

    We report numerical and experimental results obtained with an optical setup that simulates the heating and cooling processes expected in a multi-slab high-average-power laser head. We have tested the performance of an adaptive optics system consisting of a photo-controlled deformable mirror (PCDM) and a Shack-Hartmann wavefront sensor for the effective correction of the generated wavefront aberrations. The performance of the adaptive optics system is characterized for different layouts of the actuator array and for different configurations of the heating mechanisms. The numerical results are benchmarked using a PCDM, which allowed us to experimentally compare the performances of different deformable mirrors.

  12. RETRACTED: Adaptive neuro-fuzzy prediction of modulation transfer function of optical lens system

    Science.gov (United States)

    Petković, Dalibor; Shamshirband, Shahaboddin; Anuar, Nor Badrul; Md Nasir, Mohd Hairul Nizam; Pavlović, Nenad T.; Akib, Shatirah

    2014-07-01

    This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor. Sections ;1. Introduction; and ;2. Modulation transfer function;, as well as Figures 1-3, plagiarize the article published by N. Gül and M. Efe in Turk J Elec Eng & Comp Sci 18 (2010) 71 (http://journals.tubitak.gov.tr/elektrik/issues/elk-10-18-1/elk-18-1-6-0811-9.pdf). Sections ;4. Adaptive neuro-fuzzy inference system; and ;6. Conclusion; duplicate parts of the articles previously published by the corresponding author et al in ;Expert Systems with Applications; 39 (2012) 13295-13304, http://dx.doi.org/10.1016/j.eswa.2012.05.072 and ;Expert Systems with Applications; 40 (2013) 281-286, http://dx.doi.org/10.1016/j.eswa.2012.07.076. One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper is not under consideration for publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents an abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

  13. Adaptive optics in gravitational wave interferometers

    Science.gov (United States)

    Avino, Saverio; Barone, Fabrizio; Calloni, Enrico; de Rosa, Rosario; di Fiore, Luciano; Milano, Leopoldo; Restaino, Sergio R.; Tierno, Alessio

    2004-10-01

    In this paper we briefly discuss the possibility to use Adaptive Optics in long baseline interferometric gravitational wave detectors. Analisys is carried out to demonstrate the usefulness of Adaptive Optics as a method to integrate double-mode-cleaner systems, presently used or foreseen in the next generation detectors as systems for the reduction of geometrical fluctuations of input laser beam. Finally a prototype of (AO) system for the control of geometrical fluctuations in a laser beam, based on the interferometric detection of phase front, is presented. By comparison with the usual Shack-Hartmann based AO system, we show that this technique is of particular interest when high sensitivity and high band-pass are required for correction of small perturbations like, for instance, the control of the input beam of gravitational waves interferometric detectors.

  14. Optic Nerve Stimulation System with Adaptive Wireless Powering and Data Telemetry

    Directory of Open Access Journals (Sweden)

    Xing Li

    2017-12-01

    Full Text Available To treat retinal degenerative diseases, a transcorneal electrical stimulation-based system is proposed, which consists of an eye implant and an external component. The eye implant is wirelessly powered and controlled by the external component to generate the required bi-polar current pattern for transcorneal stimulation with an amplitude range of 5 μA to 320 μA, a frequency range of 10 Hz to 160 Hz and a duty ratio range of 2.5% to 20%. Power delivery control includes power boosting in preparation for stimulation, and normal power regulation that adapts to both coupling and load variations. Only one pair of coils is used for both the power link and the bi-directional data link. Except for the secondary coil, the eye implant is fully integrated on chip and is fabricated using UMC (United Microelectronics Corporation, Hsinchu, Taiwan 0.13 μm complementary metal-oxide-semiconductor (CMOS process with a size of 1.5 mm × 1.5 mm. The secondary coil is fabricated on a printed circuit board (PCB with a diameter of only 4.4 mm. After coating with biocompatible silicone, the whole implant has dimensions of 6 mm in diameter with a thickness of less than 1 mm. The whole device can be put onto the sclera and beneath the eye’s conjunctiva. System functionality and electrical performance are demonstrated with measurement results.

  15. Two fiber optics communication adapters apply to the control system of HIRFL-CSR

    International Nuclear Information System (INIS)

    Wang Dan; Zhang Shuocheng; Jing Lan; Zhang Wei; Ma Yunhai

    2006-01-01

    The authors introduced two kinds of fiber adapters that apply to the engineering HIRFL-CSR. Including design of two adapters, operational principle, and hardware construction, field of application. How to control equipment which have the standard RS232 or RS485 interface at long distance by two adapters. Replace the RS485 bus with the fiber and the 485-Fiber Adapter, solved the problem of communication disturb. The requirements of control in the national great science engineering HIRFL-CSR are fulfilled. (authors)

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

    OpenAIRE

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

    2016-01-01

    We present the last version of the PyrAmid Simulator Software for Adaptive opTics Arcetri (PASSATA), an IDL and CUDA based object oriented software developed in the Adaptive Optics group of the Arcetri observatory for Monte-Carlo end-to-end adaptive optics simulations. The original aim of this software was to evaluate the performance of a single conjugate adaptive optics system for ground based telescope with a pyramid wavefront sensor. After some years of development, the current version of ...

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

    Science.gov (United States)

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

    2013-01-01

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

  18. Real-time wavefront processors for the next generation of adaptive optics systems: a design and analysis

    Science.gov (United States)

    Truong, Tuan; Brack, Gary L.; Troy, Mitchell; Trinh, Thang; Shi, Fang; Dekany, Richard G.

    2003-02-01

    Adaptive optics (AO) systems currently under investigation will require at least two orders of magitude increase in the number of actuators, which in turn translates to effectively a 104 increase in compute latency. Since the performance of an AO system invariably improves as the compute latency decreases, it is important to study how today's computer systems will scale to address this expected increase in actuator utilization. This paper answers this question by characterizing the performance of a single deformable mirror (DM) Shack-Hartmann natural guide star AO system implemented on the present-generation digital signal processor (DSP) TMS320C6701 from Texas Instruments. We derive the compute latency of such a system in terms of a few basic parameters, such as the number of DM actuators, the number of data channels used to read out the camera pixels, the number of DSPs, the available memory bandwidth, as well as the inter-processor communication (IPC) bandwidth and the pixel transfer rate. We show how the results would scale for future systems that utilizes multiple DMs and guide stars. We demonstrate that the principal performance bottleneck of such a system is the available memory bandwidth of the processors and to lesser extent the IPC bandwidth. This paper concludes with suggestions for mitigating this bottleneck.

  19. Thirty Meter Telescope (TMT) Narrow Field Infrared Adaptive Optics System (NFIRAOS) real-time controller preliminary architecture

    Science.gov (United States)

    Kerley, Dan; Smith, Malcolm; Dunn, Jennifer; Herriot, Glen; Véran, Jean-Pierre; Boyer, Corinne; Ellerbroek, Brent; Gilles, Luc; Wang, Lianqi

    2016-08-01

    The Narrow Field Infrared Adaptive Optics System (NFIRAOS) is the first light Adaptive Optics (AO) system for the Thirty Meter Telescope (TMT). A critical component of NFIRAOS is the Real-Time Controller (RTC) subsystem which provides real-time wavefront correction by processing wavefront information to compute Deformable Mirror (DM) and Tip/Tilt Stage (TTS) commands. The National Research Council of Canada - Herzberg (NRC-H), in conjunction with TMT, has developed a preliminary design for the NFIRAOS RTC. The preliminary architecture for the RTC is comprised of several Linux-based servers. These servers are assigned various roles including: the High-Order Processing (HOP) servers, the Wavefront Corrector Controller (WCC) server, the Telemetry Engineering Display (TED) server, the Persistent Telemetry Storage (PTS) server, and additional testing and spare servers. There are up to six HOP servers that accept high-order wavefront pixels, and perform parallelized pixel processing and wavefront reconstruction to produce wavefront corrector error vectors. The WCC server performs low-order mode processing, and synchronizes and aggregates the high-order wavefront corrector error vectors from the HOP servers to generate wavefront corrector commands. The Telemetry Engineering Display (TED) server is the RTC interface to TMT and other subsystems. The TED server receives all external commands and dispatches them to the rest of the RTC servers and is responsible for aggregating several offloading and telemetry values that are reported to other subsystems within NFIRAOS and TMT. The TED server also provides the engineering GUIs and real-time displays. The Persistent Telemetry Storage (PTS) server contains fault tolerant data storage that receives and stores telemetry data, including data for Point-Spread Function Reconstruction (PSFR).

  20. Maritime Adaptive Optics Beam Control

    Science.gov (United States)

    2010-09-01

    Griot Helium Neon Class II laser with output power of 0.5 mW, operating at a wavelength of 633 nm. The science camera is an IDS uEye-2210SE CCD camera...produced by Edmund Optics, Newport/New Focus, Thor Labs, and CVI Melles Griot . Two computer controllers are used for the full experimental system. The

  1. The Durham Adaptive Optics Simulation Platform (DASP): Current status

    Science.gov (United States)

    Basden, A. G.; Bharmal, N. A.; Jenkins, D.; Morris, T. J.; Osborn, J.; Peng, J.; Staykov, L.

    2018-01-01

    The Durham Adaptive Optics Simulation Platform (DASP) is a Monte-Carlo modelling tool used for the simulation of astronomical and solar adaptive optics systems. In recent years, this tool has been used to predict the expected performance of the forthcoming extremely large telescope adaptive optics systems, and has seen the addition of several modules with new features, including Fresnel optics propagation and extended object wavefront sensing. Here, we provide an overview of the features of DASP and the situations in which it can be used. Additionally, the user tools for configuration and control are described.

  2. Overview of Advanced LIGO adaptive optics.

    Science.gov (United States)

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

    2016-10-10

    This is an overview of the adaptive optics used in Advanced LIGO (aLIGO), known as the thermal compensation system (TCS). The TCS was designed to minimize thermally induced spatial distortions in the interferometer optical modes and to provide some correction for static curvature errors in the core optics of aLIGO. The TCS is comprised of ring heater actuators, spatially tunable CO2 laser projectors, and Hartmann wavefront sensors. The system meets the requirements of correcting for nominal distortion in aLIGO to a maximum residual error of 5.4 nm rms, weighted across the laser beam, for up to 125 W of laser input power into the interferometer.

  3. High performance pseudo-analytical simulation of multi-object adaptive optics over multi-GPU systems

    KAUST Repository

    Abdelfattah, Ahmad

    2014-01-01

    Multi-object adaptive optics (MOAO) is a novel adaptive optics (AO) technique dedicated to the special case of wide-field multi-object spectrographs (MOS). It applies dedicated wavefront corrections to numerous independent tiny patches spread over a large field of view (FOV). The control of each deformable mirror (DM) is done individually using a tomographic reconstruction of the phase based on measurements from a number of wavefront sensors (WFS) pointing at natural and artificial guide stars in the field. The output of this study helps the design of a new instrument called MOSAIC, a multi-object spectrograph proposed for the European Extremely Large Telescope (E-ELT). We have developed a novel hybrid pseudo-analytical simulation scheme that allows us to accurately simulate in detail the tomographic problem. The main challenge resides in the computation of the tomographic reconstructor, which involves pseudo-inversion of a large dense symmetric matrix. The pseudo-inverse is computed using an eigenvalue decomposition, based on the divide and conquer algorithm, on multicore systems with multi-GPUs. Thanks to a new symmetric matrix-vector product (SYMV) multi-GPU kernel, our overall implementation scores significant speedups over standard numerical libraries on multicore, like Intel MKL, and up to 60% speedups over the standard MAGMA implementation on 8 Kepler K20c GPUs. At 40,000 unknowns, this appears to be the largest-scale tomographic AO matrix solver submitted to computation, to date, to our knowledge and opens new research directions for extreme scale AO simulations. © 2014 Springer International Publishing Switzerland.

  4. Adaption of optical Fresnel transform to optical Wigner transform

    International Nuclear Information System (INIS)

    Lv Cuihong; Fan Hongyi

    2010-01-01

    Enlightened by the algorithmic isomorphism between the rotation of the Wigner distribution function (WDF) and the αth fractional Fourier transform, we show that the optical Fresnel transform performed on the input through an ABCD system makes the output naturally adapting to the associated Wigner transform, i.e. there exists algorithmic isomorphism between ABCD transformation of the WDF and the optical Fresnel transform. We prove this adaption in the context of operator language. Both the single-mode and the two-mode Fresnel operators as the image of classical Fresnel transform are introduced in our discussions, while the two-mode Wigner operator in the entangled state representation is introduced for fitting the two-mode Fresnel operator.

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

    Science.gov (United States)

    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.

  6. Pipelining Computational Stages of the Tomographic Reconstructor for Multi-Object Adaptive Optics on a Multi?GPU System

    KAUST Repository

    Charara, Ali

    2014-05-04

    European Extreme Large Telescope (E-ELT) is a high priority project in ground based astronomy that aims at constructing the largest telescope ever built. MOSAIC is an instrument proposed for E-ELT using Multi- Object Adaptive Optics (MOAO) technique for astronomical telescopes, which compensates for effects of atmospheric turbulence on image quality, and operates on patches across a large FoV.

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

    Science.gov (United States)

    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.

  8. Pulse front adaptive optics in two-photon microscopy.

    Science.gov (United States)

    Sun, Bangshan; Salter, Patrick S; Booth, Martin J

    2015-11-01

    Adaptive optics has been extensively studied for the correction of phase front aberrations in optical systems. In systems using ultrafast lasers, distortions can also exist in the pulse front (contour of constant intensity in space and time), but until now their correction has been mostly unexplored due to technological limitations. In this Letter, we apply newly developed pulse front adaptive optics, for the first time to our knowledge, to practical compensation of a two-photon fluorescence microscope. With adaptive correction of the system-induced pulse front distortion, improvements beyond conventional phase correction are demonstrated.

  9. Wavefront measurement using computational adaptive optics.

    Science.gov (United States)

    South, Fredrick A; Liu, Yuan-Zhi; Bower, Andrew J; Xu, Yang; Carney, P Scott; Boppart, Stephen A

    2018-03-01

    In many optical imaging applications, it is necessary to correct for aberrations to obtain high quality images. Optical coherence tomography (OCT) provides access to the amplitude and phase of the backscattered optical field for three-dimensional (3D) imaging samples. Computational adaptive optics (CAO) modifies the phase of the OCT data in the spatial frequency domain to correct optical aberrations without using a deformable mirror, as is commonly done in hardware-based adaptive optics (AO). This provides improvement of image quality throughout the 3D volume, enabling imaging across greater depth ranges and in highly aberrated samples. However, the CAO aberration correction has a complicated relation to the imaging pupil and is not a direct measurement of the pupil aberrations. Here we present new methods for recovering the wavefront aberrations directly from the OCT data without the use of hardware adaptive optics. This enables both computational measurement and correction of optical aberrations.

  10. Adaptive multilayer optics for extreme ultraviolet wavelengths

    NARCIS (Netherlands)

    Bayraktar, Muharrem

    2015-01-01

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

  11. Development of a Low-order Adaptive Optics System at Udaipur ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... The image stabilization system comprises of a piezo driven tip-tilt mirror, a high speed camera (955 fps), a frame grabber system for sensing the overall tilt and a Linux based Intel Pentium 4 control computer with Red Hat Linux OS. The system operates under PID control. In the closed loop, an rms image ...

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    We utilized the new high-order (250-378 mode) Magellan Adaptive Optics system (MagAO) to obtain very high spatial resolution observations in ''visible light'' with MagAO's VisAO CCD camera. In the good-median seeing conditions of Magellan (0.''5-0.''7), we find MagAO delivers individual short exposure images as good as 19 mas optical resolution. Due to telescope vibrations, long exposure (60 s) r' (0.63 μm) images are slightly coarser at FWHM = 23-29 mas (Strehl ∼28%) with bright (R 1 Ori A, B, and C cluster members were obtained with VisAO. In particular, the 32 mas binary θ 1 Ori C 1 C 2 was easily resolved in non-interferometric images for the first time. The relative positions of the bright trapezium binary stars were measured with ∼0.6-5 mas accuracy. We are now sensitive to relative proper motions of just ∼0.2 mas yr –1 (∼0.4 km s –1 at 414 pc)—this is a ∼2-10 × improvement in orbital velocity accuracy compared to previous efforts. For the first time, we see clear motion of the barycenter of θ 1 Ori B 2 B 3 about θ 1 Ori B 1 . All five members of the θ 1 Ori B system appear likely to be a gravitationally bound ''mini cluster'', but we find that not all the orbits can be both circular and co-planar. The lowest mass member of the θ 1 Ori B system (B 4 ; mass ∼0.2 M ☉ ) has a very clearly detected motion (at 4.1 ± 1.3 km s –1 ; correlation = 99.9%) w.r.t. B 1 . Previous work has suggested that B 4 and B 3 are on long-term unstable orbits and will be ejected from this ''mini cluster''. However, our new ''baseline'' model of the θ 1 Ori B system suggests a more hierarchical system than previously thought, and so the ejection of B 4 may not occur for many orbits, and B 3 may be stable against ejection in the long-term. This ''ejection'' process of the lowest mass member of a ''mini cluster'' could play a major role in the formation of low-mass stars and brown dwarfs

  13. Pipelining Computational Stages of the Tomographic Reconstructor for Multi-Object Adaptive Optics on a Multi-GPU System

    KAUST Repository

    Charara, Ali

    2014-11-01

    The European Extremely Large Telescope project (E-ELT) is one of Europe\\'s highest priorities in ground-based astronomy. ELTs are built on top of a variety of highly sensitive and critical astronomical instruments. In particular, a new instrument called MOSAIC has been proposed to perform multi-object spectroscopy using the Multi-Object Adaptive Optics (MOAO) technique. The core implementation of the simulation lies in the intensive computation of a tomographic reconstruct or (TR), which is used to drive the deformable mirror in real time from the measurements. A new numerical algorithm is proposed (1) to capture the actual experimental noise and (2) to substantially speed up previous implementations by exposing more concurrency, while reducing the number of floating-point operations. Based on the Matrices Over Runtime System at Exascale numerical library (MORSE), a dynamic scheduler drives all computational stages of the tomographic reconstruct or simulation and allows to pipeline and to run tasks out-of order across different stages on heterogeneous systems, while ensuring data coherency and dependencies. The proposed TR simulation outperforms asymptotically previous state-of-the-art implementations up to 13-fold speedup. At more than 50000 unknowns, this appears to be the largest-scale AO problem submitted to computation, to date, and opens new research directions for extreme scale AO simulations. © 2014 IEEE.

  14. SEARCHING FOR BINARY Y DWARFS WITH THE GEMINI MULTI-CONJUGATE ADAPTIVE OPTICS SYSTEM (GeMS)

    International Nuclear Information System (INIS)

    Opitz, Daniela; Tinney, C. G.; Faherty, Jacqueline K.; Sweet, Sarah; Gelino, Christopher R.; Kirkpatrick, J. Davy

    2016-01-01

    The NASA Wide-field Infrared Survey Explorer (WISE) has discovered almost all the known members of the new class of Y-type brown dwarfs. Most of these Y dwarfs have been identified as isolated objects in the field. It is known that binaries with L- and T-type brown dwarf primaries are less prevalent than either M-dwarf or solar-type primaries, they tend to have smaller separations and are more frequently detected in near-equal mass configurations. The binary statistics for Y-type brown dwarfs, however, are sparse, and so it is unclear if the same trends that hold for L- and T-type brown dwarfs also hold for Y-type ones. In addition, the detection of binary companions to very cool Y dwarfs may well be the best means available for discovering even colder objects. We present results for binary properties of a sample of five WISE Y dwarfs with the Gemini Multi-Conjugate Adaptive Optics System. We find no evidence for binary companions in these data, which suggests these systems are not equal-luminosity (or equal-mass) binaries with separations larger than ∼0.5–1.9 AU. For equal-mass binaries at an age of 5 Gyr, we find that the binary binding energies ruled out by our observations (i.e., 10 42 erg) are consistent with those observed in previous studies of hotter ultra-cool dwarfs

  15. Adaptive optics imaging of the retina

    Directory of Open Access Journals (Sweden)

    Rajani Battu

    2014-01-01

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

  16. Electron density measurements for plasma adaptive optics

    Science.gov (United States)

    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.

  17. Self-referencing Mach-Zehnder interferometer as a laser system diagnostic: Active and adaptive optical systems

    International Nuclear Information System (INIS)

    Feldman, M.; Mockler, D.J.; English, R.E. Jr.; Byrd, J.L.; Salmon, J.T.

    1991-01-01

    We are incorporating a novel self-referencing Mach-Zehnder interferometer into a large scale laser system as a real time, interactive diagnostic tool for wavefront measurement. The instrument is capable of absolute wavefront measurements accurate to better than λ/10 pv over a wavelength range > 300 nm without readjustment of the optical components. This performance is achieved through the design of both refractive optics and catadioptric collimator to achromatize the Mach-Zehnder reference arm. Other features include polarization insensitivity through the use of low angles of incidence on all beamsplitters as well as an equal path length configuration that allows measurement of either broad-band or closely spaced laser-line sources. Instrument accuracy is periodically monitored in place by means of a thermally and mechanically stable wavefront reference source that is calibrated off-line with a phase conjugate interferometer. Video interferograms are analyzed using Fourier transform techniques on a computer that includes dedicated array processor. Computer and video networks maintain distributed interferometers under the control of a single analysis computer with multiple user access. 7 refs., 11 figs

  18. An improved adaptive interpolation clock recovery loop based on phase splitting algorithm for coherent optical communication system

    Science.gov (United States)

    Liu, Xuan; Liu, Bo; Zhang, Li-jia; Xin, Xiang-jun; Zhang, Qi; Wang, Yong-jun; Tian, Qing-hua; Tian, Feng; Mao, Ya-ya

    2018-01-01

    Traditional clock recovery scheme achieves timing adjustment by digital interpolation, thus recovering the sampling sequence. Based on this, an improved clock recovery architecture joint channel equalization for coherent optical communication system is presented in this paper. The loop is different from the traditional clock recovery. In order to reduce the interpolation error caused by the distortion in the frequency domain of the interpolator and to suppress the spectral mirroring generated by the sampling rate change, the proposed algorithm joint equalization, improves the original interpolator in the loop, along with adaptive filtering, and makes error compensation for the original signals according to the balanced pre-filtering signals. Then the signals are adaptive interpolated through the feedback loop. Furthermore, the phase splitting timing recovery algorithm is adopted in this paper. The time error is calculated according to the improved algorithm when there is no transition between the adjacent symbols, making calculated timing error more accurate. Meanwhile, Carrier coarse synchronization module is placed before the beginning of timing recovery to eliminate the larger frequency offset interference, which effectively adjust the sampling clock phase. In this paper, the simulation results show that the timing error is greatly reduced after the loop is changed. Based on the phase splitting algorithm, the BER and MSE are better than those in the unvaried architecture. In the fiber channel, using MQAM modulation format, after 100 km-transmission of single-mode fiber, especially when ROF(roll-off factor) values tends to 0, the algorithm shows a better clock performance under different ROFs. When SNR values are less than 8, the BER could achieve 10-2 to 10-1 magnitude. Furthermore, the proposed timing recovery is more suitable for the situation with low SNR values.

  19. Development of a Low-order Adaptive Optics System at Udaipur ...

    Indian Academy of Sciences (India)

    a Linux based Intel Pentium 4 control computer with Red Hat Linux. OS. The system operates under PID control. In the closed loop, an rms image motion of ... share a common memory through inter process communication mechanism. The first one called “the universal tracker” is largely based on the Linux device driver of ...

  20. Results from the PALM-3000 High-Order Adaptive Optics System

    Science.gov (United States)

    Roberts, Jennifer E.; Dekany, Richard G.; Burruss, Rick S.; Baranec, Christoph; Bouchez, Antonin; Croner, Ernest E.; Guiwits, Stephen R.; Hale, David D. S.; Henning, John R.; Palmer, Dean L.; hide

    2012-01-01

    The first of a new generation of high actuator density AO systems developed for large telescopes, PALM-3000 is optimized for high-contrast exoplanet science but will support operation with natural guide stars as faint as V approx. 18. PALM-3000 began commissioning in June 2011 on the Palomar 200" telescope and has to date over 60 nights of observing. The AO system consists of two Xinetics deformable mirrors, one with 66 by 66 actuators and another with 21 by 21 actuators, a Shack-Hartman WFS with four pupil sampling modes (ranging from 64 to 8 samples across the pupil), and a full vector matrix multiply real-time system capable of running at 2KHz frame rates. We present the details of the completed system, and initial results. Operating at 2 kHz with 8.3cm pupil sampling on-sky, we have achieved a K-band Strehl ratio as high as 84% in approx.1.0 arcsecond visible seeing.

  1. Adaptive optics optical coherence tomography at 1 MHz.

    Science.gov (United States)

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

    2014-12-01

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

  2. Extreme Contrast Direct Imaging of Planets and Debris disks with the Palomar P3K Adaptive Optics System and the Vector Vortex Coronagraph

    Science.gov (United States)

    Wahl, Matthew; Metchev, S. A.; Patel, R.; Serabyn, G.; PALM-3000 Adaptive Optics Team

    2013-01-01

    We present first results from using the PALM-3000 extreme adaptive optics system and imaging camera on the Hale 5m telescope. Observations using the vector vortex coronagraph have given us direct detections of the planets in the HR8799 system and the dusty debris disk around the star HD141569A. Due to the unprecedented inner working angle of the VVC, the data show a clearing within the inner ring inwards to ~20AU along the projected semi-major axis. Our observations of the disk in the K band (2.2 μm) demonstrate the power of the next generation of adaptive optics systems coupled with phase mask coronagraphy. We also show a comparison of the data reduction techniques currently being implemented in the direct imaging field. Specifically, the Locally Optimized Combination of Images (LOCI) and the Karhunen-Loeve Image Processing (KLIP) algorithms, the latter being a more robust method for resolving debris disks.

  3. Adaptive optics in coherent lidar wind measurements: A feasibility study

    Science.gov (United States)

    Leland, Robert P.

    1991-01-01

    Laser Doppler radar (lidar) is widely used for remote sensing of wind velocities. Usable wavelengths for the laser are limited by the effects of atmospheric turbulence. An adaptive optical system is proposed to compensate for turbulence effects on signal power. The feasibility of an adaptive system is considered in light of the effects of speckle from the aerosol target. It is concluded that adaptive optics is a promising technique for improving the performance of a 2 micron lidar wind measurement system. The chief technical challenges are a laser that will give the required output and pulse repetition rate, a combined Hartmann sensor and heterodyne detector, and a suitable reconstruction algorithm.

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

    Energy Technology Data Exchange (ETDEWEB)

    Close, L. M.; Males, J. R.; Morzinski, K.; Kopon, D.; Follette, K.; Rodigas, T. J.; Hinz, P.; Wu, Y-L. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Puglisi, A.; Esposito, S.; Riccardi, A.; Pinna, E.; Xompero, M.; Briguglio, R. [INAF-Osservatorio Astrofisico di Arcetri, I-50125, Firenze (Italy); Uomoto, A; Hare, T., E-mail: lclose@as.arizona.edu [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2013-09-10

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

  5. A Miniaturized Adaptive Optic Device for Optical Telecommunications, Phase I

    Data.gov (United States)

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

  6. Optical Profilometers Using Adaptive Signal Processing

    Science.gov (United States)

    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.

  7. Adaptive Optics, LLLFT Interferometry, Astronomy

    National Research Council Canada - National Science Library

    2002-01-01

    We propose to build a three telescope Michelson optical interferometer equipped with wavefront compensation technology as a demonstration and test bed for high resolution Deep Space Surveillance (DSS) and Astronomy...

  8. High Spectrum Narrowing Tolerant 112 Gb/s Dual Polarization QPSK Optical Communication Systems Using Digital Adaptive Channel Estimation

    DEFF Research Database (Denmark)

    Zhang, Xu; Pang, Xiaodan; Dogadaev, Anton Konstantinovich

    2012-01-01

    We experimentally demonstrate high spectrum narrowing tolerant 112-Gb/s QPSK polarization multiplex system based on digital adaptive channel estimation method. The proposed algorithm is able to detect severe spectrum-narrowed signal even with 20GHz 3dB bandwidth.......We experimentally demonstrate high spectrum narrowing tolerant 112-Gb/s QPSK polarization multiplex system based on digital adaptive channel estimation method. The proposed algorithm is able to detect severe spectrum-narrowed signal even with 20GHz 3dB bandwidth....

  9. Horizontal path laser communications employing MEMS adaptive optics correction

    Science.gov (United States)

    Thompson, Charles A.; Wilks, Scott C.; Brase, James M.; Young, Richard A.; Johnson, Gary W.; Ruggiero, Anthony J.

    2002-02-01

    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.

  10. Adaptive Filtering, Identification, and Control with Applications to Adaptive Optics

    National Research Council Canada - National Science Library

    Gibson, Steve

    2003-01-01

    .... Additional application areas included optical communication systems, blind identification and deconvolution, active control of noise and vibration, and detection of damage in elastic structures...

  11. Adaptive optics compensation using active illumination

    Science.gov (United States)

    Higgs, Charles; Barclay, Herbert T.; Kansky, Jan E.; Murphy, Daniel V.; Primmerman, Charles A.

    1998-09-01

    We have conducted atmospheric compensation experiments using active illumination for both adaptive-optics and tracking. Tests were performed in support of the Air Force's Airborne Laser program. The tests utilized the 5.4-km horizontal propagation range at the Lincoln Laboratory Firepond facility. The adaptive-optics beacon was provided by actively illuminating the target with a multibeam laser illuminator. A second multibeam laser illuminator was used to provide a beacon for an imaging tracker. Experiments were conducted using two different adaptive-optics illuminator configurations, as well as with point-source beacons. Data were collected over a range of atmospheric conditions. Results from these tests have helped to provide a performance benchmark for the Airborne Laser program.

  12. Wavefront sensorless adaptive optics ophthalmoscopy in the human eye

    Science.gov (United States)

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

    2011-01-01

    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. PMID:21934779

  13. Image registration for daylight adaptive optics.

    Science.gov (United States)

    Hart, Michael

    2018-03-15

    Daytime use of adaptive optics (AO) at large telescopes is hampered by shot noise from the bright sky background. Wave-front sensing may use a sodium laser guide star observed through a magneto-optical filter to suppress the background, but the laser beacon is not sensitive to overall image motion. To estimate that, laser-guided AO systems generally rely on light from the object itself, collected through the full aperture of the telescope. Daylight sets a lower limit to the brightness of an object that may be tracked at rates sufficient to overcome the image jitter. Below that limit, wave-front correction on the basis of the laser alone will yield an image that is approximately diffraction limited but that moves randomly. I describe an iterative registration algorithm that recovers high-resolution long-exposure images in this regime from a rapid series of short exposures with very low signal-to-noise ratio. The technique takes advantage of the fact that in the photon noise limit there is negligible penalty in taking short exposures, and also that once the images are recorded, it is not necessary, as in the case of an AO tracker loop, to estimate the image motion correctly and quickly on every cycle. The algorithm is likely to find application in space situational awareness, where high-resolution daytime imaging of artificial satellites is important.

  14. Launch telescope for astronomical adaptive optics

    Science.gov (United States)

    Caruso, Alberto; Novi, Andrea; Basile, Giuseppe

    2005-09-01

    The Launch Telescope Assembly (LTA) consists of a 50 cm class beam expander (angular magnification 12.5x) and it is an essential subsystem of Laser Guide Star Facility (LGSF), which provides an artificial reference star for adaptive compensation of atmospheric turbulence for one of the VLT (Very Large Telescope) 8-meters telescopes of ESO (European Southern Observatory). LTA is an afocal system, with parabolic primary and secondary mirrors, a flat 45° tertiary mirror and an exit window. It is fed with collimated Sodium laser beam, expanding and directing it along the line of sight of the 8-m telescope. Resonance backscatter from atmospheric Sodium layer at about 90 km altitude produces a point like artificial source at this altitude. The high optical quality requested for very fast optics, the severe constraints of the layout accommodation and the mass reduction made LTA a technological challenge that Galileo Avionica has been able to design, realise, align and test as requested. LTA will be positioned atop the secondary mirror unit of one of the four VLTs.

  15. A Status Report on the Thirty Meter Telescope Adaptive Optics

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... We provide an update on the recent development of the adaptive optics (AO) systems for the Thirty Meter Telescope (TMT) since mid-2011. The first light AO facility for TMT consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). This order 60 × 60 ...

  16. A Status Report on the Thirty Meter Telescope Adaptive Optics ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... We provide an update on the recent development of the adaptive optics (AO) systems for the Thirty Meter Telescope (TMT) since mid-2011. The first light AO facility for TMT consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). This order 60 × 60 ...

  17. Adaptive Optics, LLLFT Interferometry, Astronomy

    National Research Council Canada - National Science Library

    2002-01-01

    .... We will combine the wavefronts from the three telescopes using a conventional beam recombination system and acquire and track the fringes formed with a Low Light Level Fringe Tracking system (LLLFT...

  18. Turbine system and adapter

    Energy Technology Data Exchange (ETDEWEB)

    Hogberg, Nicholas Alvin; Garcia-Crespo, Andres Jose

    2017-05-30

    A turbine system and adapter are disclosed. The adapter includes a turbine attachment portion having a first geometry arranged to receive a corresponding geometry of a wheelpost of a turbine rotor, and a bucket attachment portion having a second geometry arranged to receive a corresponding geometry of a root portion of a non-metallic turbine bucket. Another adapter includes a turbine attachment portion arranged to receive a plurality of wheelposts of a turbine rotor, and a bucket attachment portion arranged to receive a plurality of non-metallic turbine buckets having single dovetail configuration root portions. The turbine system includes a turbine rotor wheel configured to receive metal buckets, at least one adapter secured to at least one wheelpost on the turbine rotor wheel, and at least one non-metallic bucket secured to the at least one adapter.

  19. Optical Airborne Tracker System

    Data.gov (United States)

    National Aeronautics and Space Administration — The Optical Airborne Tracker System (OATS) is an airborne dual-axis optical tracking system capable of pointing at any sky location or ground target.  The objectives...

  20. Analysis and Design of Adaptive OCDMA Passive Optical Networks

    Science.gov (United States)

    Hadi, Mohammad; Pakravan, Mohammad Reza

    2017-07-01

    OCDMA systems can support multiple classes of service by differentiating code parameters, power level and diversity order. In this paper, we analyze BER performance of a multi-class 1D/2D OCDMA system and propose a new approximation method that can be used to generate accurate estimation of system BER using a simple mathematical form. The proposed approximation provides insight into proper system level analysis, system level design and sensitivity of system performance to the factors such as code parameters, power level and diversity order. Considering code design, code cardinality and system performance constraints, two design problems are defined and their optimal solutions are provided. We then propose an adaptive OCDMA-PON that adaptively shares unused resources of inactive users among active ones to improve upstream system performance. Using the approximated BER expression and defined design problems, two adaptive code allocation algorithms for the adaptive OCDMA-PON are presented and their performances are evaluated by simulation. Simulation results show that the adaptive code allocation algorithms can increase average transmission rate or decrease average optical power consumption of ONUs for dynamic traffic patterns. According to the simulation results, for an adaptive OCDMA-PON with BER value of 1e-7 and user activity probability of 0.5, transmission rate (optical power consumption) can be increased (decreased) by a factor of 2.25 (0.27) compared to fixed code assignment.

  1. LGS adaptive optics system with long-pulsed sodium laser on Lijiang 1.8 meter telescope 2014-2016 observation campaign

    Science.gov (United States)

    Wei, Kai; Li, Min; Jiang, Changchun; Wei, Ling; Zheng, Wenjia; Li, Wenru; Ma, Xiaoyu; Zhou, Luchun; Jin, Kai; Bo, Yong; Zuo, Junwei; Wang, Pengyuan; Cheng, Feng; Zhang, Xiaojun; Chen, Donghong; Deng, Jijiang; Gao, Yang; Shen, Yu; Bian, Qi; Yao, Ji; Huang, Jiang; Dong, Ruoxi; Deng, Keran; Peng, Qinjun; Rao, Changhui; Xu, Zuyan; Zhang, Yudong

    2016-07-01

    During 2014-2016, the Laser guide star (LGS) adaptive optics (AO) system observation campaign has been carried out on Lijiang 1.8 meter telescope. During the campaign, two generation LGS AO systems have been developed and installed. In 2014, a long-pulsed solid Sodium prototype laser with 20W@400Hz, a beam transfer optical (BTO) system, and a laser launch telescope (LLT) with 300mm diameter were mounted onto the telescope and moved with telescope azimuth journal. At the same time, a 37-elements compact LGS AO system had been mounted on the Bent-Cassegrain focus and got its first light on observing HIP43963 (mV= 8.18mv) and reached Sr=0.27 in J Band after LGS AO compensation. In 2016, the solid Sodium laser has been upgrade to stable 32W@800Hz while D2a plus D2b repumping is used to increase the photon return, and a totally new LGS AO system with 164-elements Deformable Mirror, Linux Real Time Controller, inner closed loop Tip/tilt mirror, Multiple-PMT tracking detector is established and installed on the telescope. And the throughput for the BTO/LLT is improved nearly 20%. The campaign process, the performance of the two LGS AO systems especially the latter one, the characteristics of the BTO/LLT system and the result are present in this paper.

  2. Adaptive Optics Technology for High-Resolution Retinal Imaging

    Science.gov (United States)

    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

  3. Estimation and control of large-scale systems with an application to adaptive optics for EUV lithography

    NARCIS (Netherlands)

    Haber, A.

    2014-01-01

    Extreme UltraViolet (EUV) lithography is a new technology for production of integrated circuits. In EUV lithographic machines, optical elements are heated by absorption of exposure energy. Heating induces thermoelastic deformations of optical elements and consequently, it creates wavefront

  4. Dependence of the compensation error on the error of a sensor and corrector in an adaptive optics phase-conjugating system

    International Nuclear Information System (INIS)

    Kiyko, V V; Kislov, V I; Ofitserov, E N

    2015-01-01

    In the framework of a statistical model of an adaptive optics system (AOS) of phase conjugation, three algorithms based on an integrated mathematical approach are considered, each of them intended for minimisation of one of the following characteristics: the sensor error (in the case of an ideal corrector), the corrector error (in the case of ideal measurements) and the compensation error (with regard to discreteness and measurement noises and to incompleteness of a system of response functions of the corrector actuators). Functional and statistical relationships between the algorithms are studied and a relation is derived to ensure calculation of the mean-square compensation error as a function of the errors of the sensor and corrector with an accuracy better than 10%. Because in adjusting the AOS parameters, it is reasonable to proceed from the equality of the sensor and corrector errors, in the case the Hartmann sensor is used as a wavefront sensor, the required number of actuators in the absence of the noise component in the sensor error turns out 1.5 – 2.5 times less than the number of counts, and that difference grows with increasing measurement noise. (adaptive optics)

  5. Linear zonal atmospheric prediction for adaptive optics

    Science.gov (United States)

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

    2000-07-01

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

  6. Characterization and Operation of Liquid Crystal Adaptive Optics Phoropter

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-02-05

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

  7. Characterization and operation of a liquid crystal adaptive optics phoropter

    Science.gov (United States)

    Awwal, Abdul Ahad S.; Bauman, Brian J.; Gavel, Donald T.; Olivier, Scot S.; Jones, Steve; Silva, Dennis A.; Hardy, Joseph L.; Barnes, Thomas B.; Werner, John S.

    2003-12-01

    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.

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

    International Nuclear Information System (INIS)

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

    1997-01-01

    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

  9. Reflective afocal broadband adaptive optics scanning ophthalmoscope

    Science.gov (United States)

    Dubra, Alfredo; Sulai, Yusufu

    2011-01-01

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

  10. Adaptive intrusion data system

    International Nuclear Information System (INIS)

    Johnson, C.S.

    1976-01-01

    An Adaptive Intrusion Data System (AIDS) was developed to collect data from intrusion alarm sensors as part of an evaluation system to improve sensor performance. AIDS is a unique digital data compression, storage, and formatting system. It also incorporates capability for video selection and recording for assessment of the sensors monitored by the system. The system is software reprogrammable to numerous configurations that may be utilized for the collection of environmental, bi-level, analog and video data. The output of the system is digital tapes formatted for direct data reduction on a CDC 6400 computer, and video tapes containing timed tagged information that can be correlated with the digital data

  11. Complex adaptive systems ecology

    DEFF Research Database (Denmark)

    Sommerlund, Julie

    2003-01-01

    In the following, I will analyze two articles called Complex Adaptive Systems EcologyI & II (Molin & Molin, 1997 & 2000). The CASE-articles are some of the more quirkyarticles that have come out of the Molecular Microbial Ecology Group - a groupwhere I am currently making observational studies...

  12. Adaptive optics scanning ophthalmoscopy with annular pupils

    Science.gov (United States)

    Sulai, Yusufu N.; Dubra, Alfredo

    2012-01-01

    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. PMID:22808435

  13. Nonlinear optical systems

    CERN Document Server

    Lugiato, Luigi; Brambilla, Massimo

    2015-01-01

    Guiding graduate students and researchers through the complex world of laser physics and nonlinear optics, this book provides an in-depth exploration of the dynamics of lasers and other relevant optical systems, under the umbrella of a unitary spatio-temporal vision. Adopting a balanced approach, the book covers traditional as well as special topics in laser physics, quantum electronics and nonlinear optics, treating them from the viewpoint of nonlinear dynamical systems. These include laser emission, frequency generation, solitons, optically bistable systems, pulsations and chaos and optical pattern formation. It also provides a coherent and up-to-date treatment of the hierarchy of nonlinear optical models and of the rich variety of phenomena they describe, helping readers to understand the limits of validity of each model and the connections among the phenomena. It is ideal for graduate students and researchers in nonlinear optics, quantum electronics, laser physics and photonics.

  14. Optical system design

    CERN Document Server

    Fischer, Robert F

    2008-01-01

    Honed for more than 20 years in an SPIE professional course taught by renowned optical systems designer Robert E. Fischer, Optical System Design, Second Edition brings you the latest cutting-edge design techniques and more than 400 detailed diagrams that clearly illustrate every major procedure in optical design. This thoroughly updated resource helps you work better and faster with computer-aided optical design techniques, diffractive optics, and the latest applications, including digital imaging, telecommunications, and machine vision. No need for complex, unnecessary mathematical derivations-instead, you get hundreds of examples that break the techniques down into understandable steps. For twenty-first century optical design without the mystery, the authoritative Optical Systems Design, Second Edition features: Computer-aided design use explained through sample problems Case studies of third-millennium applications in digital imaging, sensors, lasers, machine vision, and more New chapters on optomechanic...

  15. Optical power allocation for adaptive transmissions in wavelength-division multiplexing free space optical networks

    Directory of Open Access Journals (Sweden)

    Hui Zhou

    2015-08-01

    Full Text Available Attracting increasing attention in recent years, the Free Space Optics (FSO technology has been recognized as a cost-effective wireless access technology for multi-Gigabit rate wireless networks. Radio on Free Space Optics (RoFSO provides a new approach to support various bandwidth-intensive wireless services in an optical wireless link. In an RoFSO system using wavelength-division multiplexing (WDM, it is possible to concurrently transmit multiple data streams consisting of various wireless services at very high rate. In this paper, we investigate the problem of optical power allocation under power budget and eye safety constraints for adaptive WDM transmission in RoFSO networks. We develop power allocation schemes for adaptive WDM transmissions to combat the effect of weather turbulence on RoFSO links. Simulation results show that WDM RoFSO can support high data rates even over long distance or under bad weather conditions with an adequate system design.

  16. Application of optical processing to adaptive phased array radar

    Science.gov (United States)

    Carroll, C. W.; Vijaya Kumar, B. V. K.

    1988-01-01

    The results of the investigation of the applicability of optical processing to Adaptive Phased Array Radar (APAR) data processing will be summarized. Subjects that are covered include: (1) new iterative Fourier transform based technique to determine the array antenna weight vector such that the resulting antenna pattern has nulls at desired locations; (2) obtaining the solution of the optimal Wiener weight vector by both iterative and direct methods on two laboratory Optical Linear Algebra Processing (OLAP) systems; and (3) an investigation of the effects of errors present in OLAP systems on the solution vectors.

  17. Optical measuring system with an interrogator and a polymer-based single-mode fibre optic sensor system

    DEFF Research Database (Denmark)

    2017-01-01

    The present invention relates to an optical measuring system comprising a polymer-based single-mode fibre-optic sensor system (102), an optical interrogator (101), and an optical arrangement (103) interconnecting the optical interrogator (101) and the polymer-based single-mode fibre-optic sensor...... system (102). The invention further relates to an optical interrogator adapted to be connected to a polymer-based single-mode fibre-optic sensor system via an optical arrangement. The interrogator comprises a broadband light source arrangement (104) and a spectrum analysing arrangement which receives...... and analyses light reflected from the polymer-based single- mode fibre-optic sensor system....

  18. 4th International Workshop on Adaptive Optics for Industry and Medicine

    CERN Document Server

    Wittrock, Ulrich

    2005-01-01

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

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

    Science.gov (United States)

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

    2014-08-01

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

  20. Adaptive optics for enhanced signal in CARS microscopy.

    Science.gov (United States)

    Wright, A J; Poland, S P; Girkin, J M; Freudiger, C W; Evans, C L; Xie, X S

    2007-12-24

    We report the use of adaptive optics with coherent anti-Stokes Raman scattering (CARS) microscopy for label-free deep tissue imaging based on molecular vibrational spectroscopy. The setup employs a deformable membrane mirror and a random search optimization algorithm to improve signal intensity and image quality at large sample depths. We demonstrate the ability to correct for both system and sample-induced aberrations in test samples as well as in muscle tissue in order to enhance the CARS signal. The combined system and sample-induced aberration correction increased the signal by an average factor of approximately 3x for the test samples at a depth of 700 microm and approximately 6x for muscle tissue at a depth of 260 microm. The enhanced signal and higher penetration depth offered by adaptive optics will augment CARS microscopy as an in vivo and in situ biomedical imaging modality.

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

    Science.gov (United States)

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

    2010-09-07

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

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

    NARCIS (Netherlands)

    Werkhoven, Theodorus Isaak Mattheus van

    2014-01-01

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

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

    Science.gov (United States)

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

    2012-02-01

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

  4. Fast, accurate, and robust frequency offset estimation based on modified adaptive Kalman filter in coherent optical communication system

    Science.gov (United States)

    Yang, Yanfu; Xiang, Qian; Zhang, Qun; Zhou, Zhongqing; Jiang, Wen; He, Qianwen; Yao, Yong

    2017-09-01

    We propose a joint estimation scheme for fast, accurate, and robust frequency offset (FO) estimation along with phase estimation based on modified adaptive Kalman filter (MAKF). The scheme consists of three key modules: extend Kalman filter (EKF), lock detector, and FO cycle slip recovery. The EKF module estimates time-varying phase induced by both FO and laser phase noise. The lock detector module makes decision between acquisition mode and tracking mode and consequently sets the EKF tuning parameter in an adaptive manner. The third module can detect possible cycle slip in the case of large FO and make proper correction. Based on the simulation and experimental results, the proposed MAKF has shown excellent estimation performance featuring high accuracy, fast convergence, as well as the capability of cycle slip recovery.

  5. Optically sensitive Medipix2 detector for adaptive optics wavefront sensing

    International Nuclear Information System (INIS)

    Vallerga, John; McPhate, Jason; Tremsin, Anton; Siegmund, Oswald; Mikulec, Bettina; Clark, Allan

    2005-01-01

    A new hybrid optical detector is described that has many of the attributes desired for the next generation adaptive optics (AO) wavefront sensors. The detector consists of a proximity focused microchannel plate (MCP) read out by multi-pixel application specific integrated circuit (ASIC) chips developed at CERN ('Medipix2') with individual pixels that amplify, discriminate and count input events. The detector has 256x256 pixels, zero readout noise (photon counting), can be read out at 1 kHz frame rates and is abutable on 3 sides. The Medipix2 readout chips can be electronically shuttered down to a temporal window of a few microseconds with an accuracy of 10 ns. When used in a Shack-Hartmann style wavefront sensor, a detector with 4 Medipix chips should be able to centroid approximately 5000 spots using 7x7 pixel sub-apertures resulting in very linear, off-null error correction terms. The quantum efficiency depends on the optical photocathode chosen for the bandpass of interest

  6. Complex adaptive systems ecology

    DEFF Research Database (Denmark)

    Sommerlund, Julie

    2003-01-01

    In the following, I will analyze two articles called Complex Adaptive Systems EcologyI & II (Molin & Molin, 1997 & 2000). The CASE-articles are some of the more quirkyarticles that have come out of the Molecular Microbial Ecology Group - a groupwhere I am currently making observational studies....... They are the result of acooperation between Søren Molin, professor in the group, and his brother, JanMolin, professor at Department of Organization and Industrial Sociology atCopenhagen Business School. The cooperation arises from the recognition that bothmicrobial ecology and sociology/organization theory works...

  7. The Performance of the Robo-AO Laser Guide Star Adaptive Optics System at the Kitt Peak 2.1 m Telescope

    Science.gov (United States)

    Jensen-Clem, Rebecca; Duev, Dmitry A.; Riddle, Reed; Salama, Maïssa; Baranec, Christoph; Law, Nicholas M.; Kulkarni, S. R.; Ramprakash, A. N.

    2018-01-01

    Robo-AO is an autonomous laser guide star adaptive optics (AO) system recently commissioned at the Kitt Peak 2.1 m telescope. With the ability to observe every clear night, Robo-AO at the 2.1 m telescope is the first dedicated AO observatory. This paper presents the imaging performance of the AO system in its first 18 months of operations. For a median seeing value of 1.″44, the average Strehl ratio is 4% in the i\\prime band. After post processing, the contrast ratio under sub-arcsecond seeing for a 2≤slant i\\prime ≤slant 16 primary star is five and seven magnitudes at radial offsets of 0.″5 and 1.″0, respectively. The data processing and archiving pipelines run automatically at the end of each night. The first stage of the processing pipeline shifts and adds the rapid frame rate data using techniques optimized for different signal-to-noise ratios. The second “high-contrast” stage of the pipeline is eponymously well suited to finding faint stellar companions. Currently, a range of scientific programs, including the synthetic tracking of near-Earth asteroids, the binarity of stars in young clusters, and weather on solar system planets are being undertaken with Robo-AO.

  8. Tunable Optical Polymer Systems

    National Research Council Canada - National Science Library

    Jenekhe, S. A; Bard, Allen J; Chen, S. H; Hammond, P. T; Rothberg, L. J

    2004-01-01

    This multidisciplinary university research initiative (MURI) program investigated tunable optical polymer systems suitable for large-area color-switchable coatings and devices, displays, sensors, and other electronic applications...

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  10. Adapting smartphones for low-cost optical medical imaging

    Science.gov (United States)

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

    2015-06-01

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

  11. Adaptive optics for structured illumination microscopy.

    Science.gov (United States)

    Débarre, Delphine; Botcherby, Edward J; Booth, Martin J; Wilson, Tony

    2008-06-23

    We implement wave front sensor-less adaptive optics in a structured illumination microscope. We investigate how the image formation process in this type of microscope is affected by aberrations. It is found that aberrations can be classified into two groups, those that affect imaging of the illumination pattern and those that have no influence on this pattern. We derive a set of aberration modes ideally suited to this application and use these modes as the basis for an efficient aberration correction scheme. Each mode is corrected independently through the sequential optimisation of an image quality metric. Aberration corrected imaging is demonstrated using fixed fluorescent specimens. Images are further improved using differential aberration imaging for reduction of background fluorescence.

  12. Extragalactic Fields Optimized for Adaptive Optics

    Science.gov (United States)

    2011-03-01

    field (§ 5.2). 14Prom the list compiled by 1. Brinchmann; see http://www.strw.leidenuniv.nV -jadelSurveys/ DeepFields /index.html. ISNote that in Fig...single-laser, single wave- front sensor ) AO. 5.1. Figure of Merit Any number of figures of merit can be devised for intercom- paring the performance of...optics (MOAO) and systems with faint IR tip-tilt sensors whose images are sharpened by the AO system. Future AO systems are expected to be less sensitive

  13. Adaptive Optics to Counteract Thermal Aberrations : System Design for EUV-Lithography with Sub-nm Precision

    NARCIS (Netherlands)

    Saathof, R.

    2013-01-01

    In highly precise systems the thermal expansion of system-parts is of increasing concern, since it can severely compromise its performance at sub-nanometre level. An example of such a system is an Extreme UltraViolet (EUV)-lithography machine that is used in the semi-conductor industry to project

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

    Science.gov (United States)

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

    2011-07-01

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

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-02-04

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

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

    Science.gov (United States)

    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.

  18. FIBER OPTIC LIGHTING SYSTEMS

    Directory of Open Access Journals (Sweden)

    Munir BATUR

    2013-01-01

    Full Text Available Recently there have been many important and valuable developments in the communication industry. The huge increase in the sound, data and visual communications has caused a parallel increase in the demand for systems with wider capacity, higher speed and higher quality. Communication systems that use light to transfer data are immensely increased. There have recently many systems in which glass or plastic fiber cables were developed for light wave to be transmitted from a source to a target place. Fiber optic systems, are nowadays widely used in energy transmission control systems, medicine, industry and lighting. The basics of the system is, movement of light from one point to another point in fiber cable with reflections. Fiber optic lighting systems are quite secure than other lighting systems and have flexibility for realizing many different designs. This situation makes fiber optics an alternative for other lighting systems. Fiber optic lighting systems usage is increasing day-by-day in our life. In this article, these systems are discussed in detail.

  19. Wavefront sensing and adaptive optics in strong turbulence

    Science.gov (United States)

    Mackey, Ruth; Dainty, Christopher

    2005-06-01

    When light propagates through the atmosphere the fluctuating refractive index caused by temperature gradients, humidity fluctuations and the wind mixing of air cause the phase of the optical field to be corrupted. In strong turbulence, over horizontal paths or at large zenith angles, the phase aberration is converted to intensity variation (scintillation) as interference within the beam and diffraction effects produce the peaks and zeros of a speckle-like pattern. At the zeros of intensity the phase becomes indeterminate as both the real and imaginary parts of the field go to zero. The wavefront is no longer continuous but contains dislocations along lines connecting phase singularities of opposite rotation. Conventional adaptive optics techniques of wavefront sensing and wavefront reconstruction do not account for discontinuous phase functions and hence can only conjugate an averaged, continuous wavefront. We are developing an adaptive optics system that can cope with dislocations in the phase function for potential use in a line-of-sight optical communications link. Using a ferroelectric liquid crystal spatial light modulator (FLC SLM) to generate dynamic atmospheric phase screens in the laboratory, we simulate strong scintillation conditions where high densities of phase singularities exist in order to compare wavefront sensors for tolerance to scintillation and accuracy of wavefront recovery.

  20. Control algorithms and applications of the wavefront sensorless adaptive optics

    Science.gov (United States)

    Ma, Liang; Wang, Bin; Zhou, Yuanshen; Yang, Huizhen

    2017-10-01

    Compared with the conventional adaptive optics (AO) system, the wavefront sensorless (WFSless) AO system need not to measure the wavefront and reconstruct it. It is simpler than the conventional AO in system architecture and can be applied to the complex conditions. Based on the analysis of principle and system model of the WFSless AO system, wavefront correction methods of the WFSless AO system were divided into two categories: model-free-based and model-based control algorithms. The WFSless AO system based on model-free-based control algorithms commonly considers the performance metric as a function of the control parameters and then uses certain control algorithm to improve the performance metric. The model-based control algorithms include modal control algorithms, nonlinear control algorithms and control algorithms based on geometrical optics. Based on the brief description of above typical control algorithms, hybrid methods combining the model-free-based control algorithm with the model-based control algorithm were generalized. Additionally, characteristics of various control algorithms were compared and analyzed. We also discussed the extensive applications of WFSless AO system in free space optical communication (FSO), retinal imaging in the human eye, confocal microscope, coherent beam combination (CBC) techniques and extended objects.

  1. Easy and versatile adaptive optics setup with deformable lens for high-resolution microscopy

    Science.gov (United States)

    Pozzi, P.; Quintavalla, M.; Verstraete, H.; Bijlsma, H.; Bonora, S.; Verhaegen, M.

    2017-06-01

    It has been widely proven in literature that most optical microscopy techniques can greatly benefit from the application of adaptive optics correction of phase aberrations through an adaptive optical element, such as a deformable mirror or a spatial light modulator. However, adaptive optics is not yet widely adopted in the life sciences community, mostly due to the lack of adaptive commercial microscopy systems, and the inherent technical difficulty in modifying an existing microscopy setup to integrate an adaptive element, both on the software and hardware sides. We present a plug-and-play adaptive optics module for generic optical microscopes, based on a prototype refractive 18 actuators adaptive optical element, which can be inserted in any microscope between the objective and the microscope body. Correction is performed in a sensorless fashion, optimizing image quality metrics of the image presented to the user on screen. The results presented show how an end-user oriented commercial confocal laser scanning microscope (Leica SP5) can be upgraded with adaptive optics with minor hardware modifications, and no changes to the microscope control software.

  2. Adaptivity in Professional Printing Systems

    NARCIS (Netherlands)

    Verriet, J.H.; Basten, T; Hamberg, R.; Reckers, F.J.; Somers, L.

    2013-01-01

    There is a constant pressure on developers of embedded systems to simultaneously increase system functionality and to decrease development costs. Aviable way to obtain a better system performance with the same physical hardware is adaptivity: a system should be able to adapt itself to dynamically

  3. Optical Complex Systems 2008

    Science.gov (United States)

    Brun, Guillaume

    The Optical Complex Systems are more and more in the heart of various systems that industrial applications bring to everyday life. From environment up to spatial applications, OCS is also relevant in monitoring, transportation, robotics, life sciences, sub-marine, and even for agricultural purposes.

  4. Based on ground station adaptive optics for laser communications demonstration platform structures

    Science.gov (United States)

    Zhang, Lei; Tong, Shoufeng; Wang, Haozeng; Yang, Hongkun

    2013-08-01

    With the rapid development of modern science and technology in astronomical imaging, optical communications, optical radar, optical information processing, high-precision ranging, tracking, guidance, and remote sensing, light waves propagating in the medium, especially in the turbulent atmosphere spread more and more important. Atmospheric turbulence is one of the main factors which have influence on the performance of a laser communication system. Adaptive optics technology is an important means to solve the problem of atmospheric turbulence. This paper states how adaptive optics technique can be used in space laser communication system to compensate atmospheric turbulence when laser beam transmission through it. The core content of adaptive optics is correct laser beam wave-front disturbance in real-time,with it to enhance optical system imaging quality and the next aim is reach the level of diffraction limitation. Adaptive optics system consists of wave-front detection, wave-front control and wave-front correction . The demo platform including: atmospheric turbulence simulation unit、adaptive correction unit、signal transmitting and receiving unit. Liquid crystal spatial light modulator applications in adaptive optics system and the turbulence simulation system introduced. And used zernike polynomials method to produce atmospheric turbulence phase screen simulation analysis. Simulation results show that: in the low spatial frequency components, the atmospheric turbulence phase screen generated by Zernike polynomial method consistent with the theoretical values, but in the high spatial frequency components, the simulation results with large difference between the theoretical values. In addition, the simulation results also show that: we can change the distribution of turbulence in the atmospheric turbulence phase screen by increasing the Zernike polynomials of orders or change the receiving apertures, but to calculate the large calculate the complex and

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

    Science.gov (United States)

    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.

  6. Photonic crystal-adaptive optical devices

    DEFF Research Database (Denmark)

    Buss, Thomas

    is investigated and switching times and driving voltages are competitive with existing non-projection liquid crystal displays. The principle has been investigated for use in projection displays but may also be applied to other applications such as cell manipulation in lab-on-a-chip systems and reconfigurable...... are minimized, thus allowing a homogeneous, glare-free, white-light daylighting into the room. Even more functionality can be achieved when the optical effects are tunable or reconfigurable. This is investigated with photonic crystal dye lasers. These lasers combine a photonic crystal resonator with a dye-doped...

  7. Adaptive optical probe design for optical coherence tomography and microscopy using tunable optics.

    Science.gov (United States)

    Choi, Minseog; Lee, Seungwan; Chang, Jong-Hyeon; Lee, Eunsung; Jung, Kyu-Dong; Kim, Woonbae

    2013-01-28

    We present a tunable, adaptive optical imaging probe for multimodal imaging such as optical coherence tomography and microscopy. The probe is compatible with forward-looking scanning laser imaging devices such as an endoscope. The lens configuration includes a tunable iris and two varifocal lenses, both driven by microelectrofluidics, as well as several conventional fixed focus lenses. The modulation transfer function and spot size in the focal plane is evaluated, and we show using optical simulations that there are three possible imaging modes with different transverse resolutions and focal depths.

  8. Adaptive optics improves multiphoton super-resolution imaging

    Science.gov (United States)

    Zheng, Wei; Wu, Yicong; Winter, Peter; Shroff, Hari

    2018-02-01

    Three dimensional (3D) fluorescence microscopy has been essential for biological studies. It allows interrogation of structure and function at spatial scales spanning the macromolecular, cellular, and tissue levels. Critical factors to consider in 3D microscopy include spatial resolution, signal-to-noise (SNR), signal-to-background (SBR), and temporal resolution. Maintaining high quality imaging becomes progressively more difficult at increasing depth (where optical aberrations, induced by inhomogeneities of refractive index in the sample, degrade resolution and SNR), and in thick or densely labeled samples (where out-of-focus background can swamp the valuable, in-focus-signal from each plane). In this report, we introduce our new instrumentation to address these problems. A multiphoton structured illumination microscope was simply modified to integrate an adpative optics system for optical aberrations correction. Firstly, the optical aberrations are determined using direct wavefront sensing with a nonlinear guide star and subsequently corrected using a deformable mirror, restoring super-resolution information. We demonstrate the flexibility of our adaptive optics approach on a variety of semi-transparent samples, including bead phantoms, cultured cells in collagen gels and biological tissues. The performance of our super-resolution microscope is improved in all of these samples, as peak intensity is increased (up to 40-fold) and resolution recovered (up to 176+/-10 nm laterally and 729+/-39 nm axially) at depths up to 250 μm from the coverslip surface.

  9. Design of least-mean-square based adaptive optical equalizers

    Science.gov (United States)

    Ghosh, Anjan; Barner, Jim; Paparao, Palacharla

    1992-07-01

    Dispersion effects and attenuation over long distances cause degradation to a signal waveform in any communication channel, even optical fibers. Equalization is the process of restoring the shape of the signal waveform. Most current equalization techniques to combat signal distortion in optical fibers rely upon complex electronic realizations to process data converted from the optical signal of interest. The focus of this paper is to study the feasibility of designing efficient optical adaptive equalizers for the optical processing of guided lightwave signal waveforms corrupted by dispersion and attenuation effects varying slowly with time. The least-mean-square algorithm is used to adapt an equalizer's weights in real-time as the optical channel varies. The convergence and learning capabilities of the equalizer are analyzed as a function of the equalizer parameters and optical hardware errors. Optimal equalizer parameters are determined through analysis and numerical simulation such that the effects of optical errors and noise are reduced.

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

    Science.gov (United States)

    Burns, W. Robert

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

  11. Computational adaptive optics for broadband optical interferometric tomography of biological tissue.

    Science.gov (United States)

    Adie, Steven G; Graf, Benedikt W; Ahmad, Adeel; Carney, P Scott; Boppart, Stephen A

    2012-05-08

    Aberrations in optical microscopy reduce image resolution and contrast, and can limit imaging depth when focusing into biological samples. Static correction of aberrations may be achieved through appropriate lens design, but this approach does not offer the flexibility of simultaneously correcting aberrations for all imaging depths, nor the adaptability to correct for sample-specific aberrations for high-quality tomographic optical imaging. Incorporation of adaptive optics (AO) methods have demonstrated considerable improvement in optical image contrast and resolution in noninterferometric microscopy techniques, as well as in optical coherence tomography. Here we present a method to correct aberrations in a tomogram rather than the beam of a broadband optical interferometry system. Based on Fourier optics principles, we correct aberrations of a virtual pupil using Zernike polynomials. When used in conjunction with the computed imaging method interferometric synthetic aperture microscopy, this computational AO enables object reconstruction (within the single scattering limit) with ideal focal-plane resolution at all depths. Tomographic reconstructions of tissue phantoms containing subresolution titanium-dioxide particles and of ex vivo rat lung tissue demonstrate aberration correction in datasets acquired with a highly astigmatic illumination beam. These results also demonstrate that imaging with an aberrated astigmatic beam provides the advantage of a more uniform depth-dependent signal compared to imaging with a standard gaussian beam. With further work, computational AO could enable the replacement of complicated and expensive optical hardware components with algorithms implemented on a standard desktop computer, making high-resolution 3D interferometric tomography accessible to a wider group of users and nonspecialists.

  12. SOAR Adaptive Optics Observations of Young Stellar Objects

    Science.gov (United States)

    Briceno, Cesar

    2018-01-01

    I present results from recent studies of nearby star-forming regions using the SOAR 4.1m telescope Ground-layer Adaptive Optics system.Using narrow-band Hα and [SII] imaging we discovered a spectacular extended Herbig-Haro jet powered by a 26 MJup young brown dwarf located in the vicinity of the σ Orionis cluster. The collimated structure of multiple knots spans 0.26 pc, making it a scaled down version of the parsec-length jets seen in T Tauri stars, and the first substellar analog of an HH jet system.In the ε Chamaeleon stellar group we carried out an Adaptive Optics-aided speckle imaging study of 47 members and candidate members, to characterize the multiplicity of this, one of the nearest groups of young (~3-5 Myr) stars. We resolved 10 new binary pairs, 5 previously know binaries and two triple systems. We find a companion frequency of 0.010±0.04 per decade of separation, in the 4 to 300 AU separation range, a result comparable to main sequence dwarfs in the field. However, the more massive association members, with B and A spectral types, all have companions in this separation range. Finally, we provide new constraints on the orbital elements of the ε Cha triple system.

  13. Optimal model-based sensorless adaptive optics for epifluorescence microscopy.

    Science.gov (United States)

    Pozzi, Paolo; Soloviev, Oleg; Wilding, Dean; Vdovin, Gleb; Verhaegen, Michel

    2018-01-01

    We report on a universal sample-independent sensorless adaptive optics method, based on modal optimization of the second moment of the fluorescence emission from a point-like excitation. Our method employs a sample-independent precalibration, performed only once for the particular system, to establish the direct relation between the image quality and the aberration. The method is potentially applicable to any form of microscopy with epifluorescence detection, including the practically important case of incoherent fluorescence emission from a three dimensional object, through minor hardware modifications. We have applied the technique successfully to a widefield epifluorescence microscope and to a multiaperture confocal microscope.

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

    Science.gov (United States)

    Liu, Zhuolin

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

  15. Adaptive control for chaotic systems

    Energy Technology Data Exchange (ETDEWEB)

    Hua Changchun E-mail: cch@ysu.edu.cn; Guan Xinping

    2004-10-01

    Control problem of chaotic system is investigated via adaptive method. A fairly simple adaptive controller is constructed, which can control chaotic systems to unstable fixed points. The precise mathematical models of chaotic systems need not be known and only the fixed points and the dimensions of chaotic systems are required to be known. Simulations on controlling different chaotic systems are investigated and the results show the validity and feasibility of the proposed controller.

  16. Optical switching systems using nanostructures

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    2004-01-01

    High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems.......High capacity multiservice optical networks require compact and efficient switches. The potential benefits of optical switch elements based on nanostructured material are reviewed considering various material systems....

  17. Optical implementations of associative networks with versatile adaptive learning capabilities.

    Science.gov (United States)

    Fisher, A D; Lippincott, W L; Lee, J N

    1987-12-01

    Optical associative, parallel-processing architectures are being developed using a multimodule approach, where a number of smaller, adaptive, associative modules are nonlinearly interconnected and cascaded under the guidance of a variety of organizational principles to structure larger architectures for solving specific problems. A number of novel optical implementations with versatile adaptive learning capabilities are presented for the individual associative modules, including holographic configurations and five specific electrooptic configurations. The practical issues involved in real optical architectures are analyzed, and actual laboratory optical implementations of associative modules based on Hebbian and Widrow-Hoff learning rules are discussed, including successful experimental demonstrations of their operation.

  18. Design and optimization of an adaptive optics system for a high-average-power multi-slab laser (HiLASE)

    Czech Academy of Sciences Publication Activity Database

    Pilař, Jan; Slezák, Jiří; Sikocinski, Pawel; Divoký, Martin; Sawicka, Magdalena; Bonora, Stefano; Lucianetti, Antonio; Mocek, Tomáš; Jelínková, H.

    2014-01-01

    Roč. 53, č. 15 (2014), 3255-3261 ISSN 1559-128X R&D Projects: GA MŠk ED2.1.00/01.0027; GA MŠk EE2.3.20.0143; GA MŠk EE2.3.30.0057 Grant - others:HILASE(XE) CZ.1.05/2.1.00/01.0027; OP VK 6(XE) CZ.1.07/2.3.00/20.0143; OP VK 4 POSTDOK(XE) CZ.1.07/2.3.00/30.0057 Institutional support: RVO:68378271 Keywords : adaptive optics * multislab * amplifier * wavefront Subject RIV: BH - Optics , Masers, Lasers Impact factor: 1.784, year: 2014

  19. Aurora laser optical system

    International Nuclear Information System (INIS)

    Hanlon, J.A.; McLeod, J.

    1987-01-01

    Aurora is the Los Alamos short-pulse high-power krypton fluoride laser system. It is primarily an end-to-end technology demonstration prototype for large-scale UV laser systems of interest for short-wavelength inertial confinement fusion (ICF) investigations. The system is designed to employ optical angular multiplexing and aerial amplification by electron-beam-driven KrF laser amplifiers to deliver to ICF targets a stack of pulses with a duration of 5 ns containing several kilojoules at a wavelength of 248 nm. A program of high-energy density plasma physics investigations is now planned, and a sophisticated target chamber was constructed. The authors describe the design of the optical system for Aurora and report its status. This optical system was designed and is being constructed in two phases. The first phase carries only through the amplifier train and does not include a target chamber or any demultiplexing. Installation should be complete, and some performance results should be available. The second phase provides demultiplexing and carries the laser light to target. The complete design is reported

  20. Adaptive optics stochastic optical reconstruction microscopy (AO-STORM) by particle swarm optimization.

    Science.gov (United States)

    Tehrani, Kayvan F; Zhang, Yiwen; Shen, Ping; Kner, Peter

    2017-11-01

    Stochastic optical reconstruction microscopy (STORM) can achieve resolutions of better than 20nm imaging single fluorescently labeled cells. However, when optical aberrations induced by larger biological samples degrade the point spread function (PSF), the localization accuracy and number of localizations are both reduced, destroying the resolution of STORM. Adaptive optics (AO) can be used to correct the wavefront, restoring the high resolution of STORM. A challenge for AO-STORM microscopy is the development of robust optimization algorithms which can efficiently correct the wavefront from stochastic raw STORM images. Here we present the implementation of a particle swarm optimization (PSO) approach with a Fourier metric for real-time correction of wavefront aberrations during STORM acquisition. We apply our approach to imaging boutons 100 μm deep inside the central nervous system (CNS) of Drosophila melanogaster larvae achieving a resolution of 146 nm.

  1. Digital adaptive optics confocal microscopy based on iterative retrieval of optical aberration from a guidestar hologram.

    Science.gov (United States)

    Liu, Changgeng; Thapa, Damber; Yao, Xincheng

    2017-04-03

    Guidestar hologram based digital adaptive optics (DAO) is one recently emerging active imaging modality. It records each complex distorted line field reflected or scattered from the sample by an off-axis digital hologram, measures the optical aberration from a separate off-axis digital guidestar hologram, and removes the optical aberration from the distorted line fields by numerical processing. In previously demonstrated DAO systems, the optical aberration was directly retrieved from the guidestar hologram by taking its Fourier transform and extracting the phase term. For the direct retrieval method (DRM), when the sample is not coincident with the guidestar focal plane, the accuracy of the optical aberration retrieved by DRM undergoes a fast decay, leading to quality deterioration of corrected images. To tackle this problem, we explore here an image metrics-based iterative method (MIM) to retrieve the optical aberration from the guidestar hologram. Using an aberrated objective lens and scattering samples, we demonstrate that MIM can improve the accuracy of the retrieved aberrations from both focused and defocused guidestar holograms, compared to DRM, to improve the robustness of the DAO.

  2. OPTICAL WIRELESS COMMUNICATION SYSTEM

    Directory of Open Access Journals (Sweden)

    JOSHUA L.Y. CHIENG

    2016-02-01

    Full Text Available The growing demand of bandwidth in this modern internet age has been testing the existing telecommunication infrastructures around the world. With broadband speeds moving towards the region of Gbps and Tbps, many researches have begun on the development of using optical wireless technology as feasible and future methods to the current wireless technology. Unlike the existing radio frequency wireless applications, optical wireless uses electromagnetic spectrums that are unlicensed and free. With that, this project aim to understand and gain better understanding of optical wireless communication system by building an experimental and simulated model. The quality of service and system performance will be investigated and reviewed. This project employs laser diode as the propagation medium and successfully transferred audio signals as far as 15 meters. On its quality of service, results of the project model reveal that the bit error rate increases, signal-to-noise ratio and quality factor decreases as the link distance between the transmitter and receiver increases. OptiSystem was used to build the simulated model and MATLAB was used to assist signal-to-noise ratio calculations. By comparing the simulated and experimental receiver’s power output, the experimental model’s efficiency is at 66.3%. Other than the system’s performance, challenges and factors affecting the system have been investigated and discussed. Such challenges include beam divergence, misalignment and particle absorption.

  3. Large stroke actuators and mirror devices for ocular adaptive optics

    Science.gov (United States)

    Wu, Xingtao; Li, Hong; Yao, Li; Ou, Haijiang; Pang, Chaoyang

    2012-03-01

    After laboratory studies have demonstrated that the DM-based adaptive optics ophthalmic instruments are promising for future clinical applications, the next step would be to further enhance the functionality of ocular adaptive optics for research and commercialize it for clinical applications. The first essential requirement is the stroke which should cover most wavefront errors of the eyes in clinical population, for which, we presented here design, modeling, and experimental performance of PMN-PT unimorph actuators suitable for generating large stroke up to 50μm per 1-mm pixel in order to cover wavefront correction for older adults and patients with diseased eyes. Clinical acceptance will also requires DMs to be low cost, have a small form factor, running low power, have satisfactory speed, and be an easy add-on for system integration, thus we further presented an effort of developing a high voltage amplifier (HVA) based application specific integrated circuits (ASIC) for driving the mirror actuators with significantly reduced power and system form factors.

  4. Optically pumped laser systems

    International Nuclear Information System (INIS)

    DeMaria, A.J.; Mack, M.E.

    1975-01-01

    Laser systems which are pumped by an electric discharge formed in a gas are disclosed. The discharge is in the form of a vortex stabilized electric arc which is triggered with an auxiliary energy source. At high enough repetition rates residual ionization between successive pulses contributes to the pulse stabilization. The arc and the gain medium are positioned inside an optical pumping cavity where light from the arc is coupled directly into the gain medium

  5. First experiences with a slitlamp-adapted optical coherence tomography (OCT) system in the anterior and posterior segment of the eye

    Science.gov (United States)

    Hoerauf, Hans; Scholz, Christian; Engelhardt, Ralf; Koch, Peter; Laqua, Horst; Birngruber, Reginald

    1999-02-01

    Optical Coherence Tomography (OCT) is a new in vivo imaging device in ophthalmology. We investigated the diagnostic potentials of a slitlamp-adapted OCT in the examination of not only the posterior but also the anterior segment in vivo. Patients were examined with a new prototype of a slitlamp- adapted OCT (Fa.Schwind, D-Kleinostheim) in the anterior and posterior segment using 100 - 200 axial scans with 50 Hz scan frequency. The scan length is variable up to 7.5 mm. The software allows to evaluate the images in gray scale or false color. By the slitlamp-adapted OCT all anatomic structures and morphological changes anterior to the attenuating iris pigment epithelium including the anterior chamber angle can be demonstrated and measured precisely. Within the pupillary opening OCT-imaging of cataract, secondary cataract formation as well as the anterior vitreous can be performed. The slitlamp-adapted OCT also allows direct biomicroscopic control of the measured area in examinations of the posterior segment. The slitlamp-adapted OCT provides a new and helpful diagnostic tool, which allows a precise examination of the anterior and posterior segment of the eye. The advantage of this new method lies in the combination of the familiar examination technique and the simultaneous slitlamp view, which provides an exact position control. It is possible to do pachymetric studies of the cornea after photorefractive and phototherapeutic therapy. Of importance is the objective measurement of the chamber angle, which may improve pre- and postoperative evaluation and allow a better follow up documentation of glaucoma patients.

  6. Design of the Dual Conjugate Adaptive Optics Test-bed

    Science.gov (United States)

    Sharf, Inna; Bell, K.; Crampton, D.; Fitzsimmons, J.; Herriot, Glen; Jolissaint, Laurent; Lee, B.; Richardson, H.; van der Kamp, D.; Veran, Jean-Pierre

    order to quantify the quality of the correction achieved with the DM's. A mini-wavescope, also supplied by AOA, will be part of the test-bed and is intended for use as an auxilliary tool for system calibration and identification. The foreoptics of the complete layout emulates a 32 cm, F/40 telescope, which itself was scaled down from an 8 meter telescope, while maintaining a 2' field of view. The foreoptics entrance beam diameter is 30 mm. The tip-tilt mirror procured from Ball Aerospace is placed at 0km in the foreoptics, before the deformable mirrors. A turbulence generator and a source simulator must be constructed for the test-bed since it is intended for use as a stand-alone research facility. Several concepts were considered for the turbulence generator: a holographic simulator, a spatial light modulator based on liquid-crystal technology, a phase plate based simulator and the hot-air turbulence generator. The latter was identified as the most suitable concept for our facility, after comparing the versatility, capabilities, and cost of the alternatives. The proposed design follows closely that developed by [Jolissaint, 2000] and aims to produce turbulence with Cn2 delta h ~ O (10-10) and D/r0 of approximately 8. With an appropriately designed fold of the beam, a single hot-air turbulator can be used to provide both turbulence layers for the beam. The source simulator will accommodate three guide stars with a fixed triangular geometry and a white science source that can be placed at an arbitrary location in the field of view. The guide stars can be located either at infinity to emulate NGS, or at 90 km to emulate sodium backscatter produced with lasers in a real adaptive optics system. Since the GS are held fixed above the turbulence, they can also be used to derive tip-tilt information, thus obviating the need for Natural Guide Stars. The dual-layer adaptive optics test-bed presented in this poster is expected to be fully operational by the middle of 2002. Parts

  7. Optical systems engineering - A tutorial

    Science.gov (United States)

    Wyman, C. L.

    1979-01-01

    The paper examines the use of the systems engineering approach in the design of optical systems, noting that the use of such an approach which involves an integrated interdisciplinary approach to the development of systems is most appropriate for optics. It is shown that the high precision character of optics leads to complex and subtle effects on optical system performance, resulting from structural, thermal dynamical, control system, and manufacturing and assembly considerations. Attention is given to communication problems that often occur among users and optical engineers due to the unique factors of optical systems. It is concluded that it is essential that the optics community provide leadership to resolve communication problems and fully formalize the field of optical systems engineering.

  8. Adaptive Filtering and System Identification

    National Research Council Canada - National Science Library

    Gibson, Steve

    2007-01-01

    .... Additional application areas include optical wireless communication systems, blind identification and deconvolution in wireless communications, and active control of noise and vibration. This report discusses recent collaborations with the Air Force Research Laboratory (AFRL) and industry.

  9. Optical fiber inspection system

    Science.gov (United States)

    Moore, Francis W.

    1987-01-01

    A remote optical inspection system including an inspection head. The inspection head has a passageway through which pellets or other objects are passed. A window is provided along the passageway through which light is beamed against the objects being inspected. A plurality of lens assemblies are arranged about the window so that reflected light can be gathered and transferred to a plurality of coherent optical fiber light guides. The light guides transfer the light images to a television or other image transducer which converts the optical images into a representative electronic signal. The electronic signal can then be displayed on a signal viewer such as a television monitor for inspection by a person. A staging means can be used to support the objects for viewing through the window. Routing means can be used to direct inspected objects into appropriate exit passages for accepted or rejected objects. The inspected objects are advantageously fed in a singular manner to the staging means and routing means. The inspection system is advantageously used in an enclosure when toxic or hazardous materials are being inspected.

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

    Science.gov (United States)

    Madec, P.-Y.

    2012-07-01

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

  11. Photometric Calibration of the Gemini South Adaptive Optics Imager

    Science.gov (United States)

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

    2017-01-01

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

  12. Meaning of visualizing retinal cone mosaic on adaptive optics images.

    Science.gov (United States)

    Jacob, Julie; Paques, Michel; Krivosic, Valérie; Dupas, Bénédicte; Couturier, Aude; Kulcsar, Caroline; Tadayoni, Ramin; Massin, Pascale; Gaudric, Alain

    2015-01-01

    To explore the anatomic correlation of the retinal cone mosaic on adaptive optics images. Retrospective nonconsecutive observational case series. A retrospective review of the multimodal imaging charts of 6 patients with focal alteration of the cone mosaic on adaptive optics was performed. Retinal diseases included acute posterior multifocal placoid pigment epitheliopathy (n = 1), hydroxychloroquine retinopathy (n = 1), and macular telangiectasia type 2 (n = 4). High-resolution retinal images were obtained using a flood-illumination adaptive optics camera. Images were recorded using standard imaging modalities: color and red-free fundus camera photography; infrared reflectance scanning laser ophthalmoscopy, fluorescein angiography, indocyanine green angiography, and spectral-domain optical coherence tomography (OCT) images. On OCT, in the marginal zone of the lesions, a disappearance of the interdigitation zone was observed, while the ellipsoid zone was preserved. Image recording demonstrated that such attenuation of the interdigitation zone co-localized with the disappearance of the cone mosaic on adaptive optics images. In 1 case, the restoration of the interdigitation zone paralleled that of the cone mosaic after a 2-month follow-up. Our results suggest that the interdigitation zone could contribute substantially to the reflectance of the cone photoreceptor mosaic. The absence of cones on adaptive optics images does not necessarily mean photoreceptor cell death. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. W. M. Keck Observatory's next-generation adaptive optics facility

    Science.gov (United States)

    Wizinowich, P.; Adkins, S.; Dekany, R.; Gavel, D.; Max, C.; Bartos, R.; Bell, J.; Bouchez, A.; Chin, J.; Conrad, A.; Delacroix, A.; Johansson, E.; Kupke, R.; Lockwood, C.; Lyke, J.; Marchis, F.; McGrath, E.; Medeiros, D.; Morris, M.; Morrison, D.; Neyman, C.; Panteleev, S.; Pollard, M.; Reinig, M.; Stalcup, T.; Thomas, S.; Troy, M.; Tsubota, K.; Velur, V.; Wallace, K.; Wetherell, E.

    2010-07-01

    We report on the preliminary design of W.M. Keck Observatory's (WMKO's) next-generation adaptive optics (NGAO) facility. This facility is designed to address key science questions including understanding the formation and evolution of today's galaxies, measuring dark matter in our galaxy and beyond, testing the theory of general relativity in the Galactic Center, understanding the formation of planetary systems around nearby stars, and exploring the origins of our own solar system. The requirements derived from these science questions have resulted in NGAO being designed to have near diffraction-limited performance in the near-IR (K-Strehl ~ 80%) over narrow fields (benefit quantitative astronomy, a cooled science path to reduce thermal background, and a high-efficiency science instrument providing imaging and integral field spectroscopy.

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

    Energy Technology Data Exchange (ETDEWEB)

    Poyneer, L; Veran, J P

    2010-03-29

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

  15. PROSPECT: Optical Calibration System

    Science.gov (United States)

    Trinh, Ken; Prospect Collaboration

    2016-09-01

    The Precision Reactor Oscillation and SPECTrum Experiment (PROSPECT), is a short baseline, reactor neutrino experiment which focuses on measurements of the flux and energy spectrum of antineutrinos emitted from the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Using these measurements, PROSPECT will probe for eV-scale sterile neutrinos while making a high precision measurement of the U-235 antineutrino spectrum. PROSPECT contains two phases; the first phase consists of a mobile detector near the reactor core while the second phase adds a larger fixed detector further from the core. The PROSPECT Phase 1 detector consists of a 2ton optically segmented liquid scintillator with each segment read-out by two photomultiplier tubes (PMTs). The PMTs are calibrated with a photon source generated by a nanosecond pulsed laser. In this project, we developed a plan to determine the effectiveness of a 450nm fiber-pigtailed diode laser as it coupled with several modules including an optical fiber splitter, an optical diffuser, and an attenuator. The project tested for the system ability to deliver light uniformly to each of the cells in the detector. We will present the design and result of this project as well as discuss how it will be implemented in PROSPECT.

  16. Optical systems for synchrotron radiation

    International Nuclear Information System (INIS)

    Howells, M.R.

    1985-12-01

    Various fundamental topics which underlie the design and use of optical systems for synchrotron radiation are considered from the viewpoint of linear system theory. These topics include the damped harmonic oscillator, free space propagation of an optical field, electromagnetic theory of optical properties of materials, theory of dispersion, and the Kramers-Kronig relations. 32 refs., 5 figs

  17. Control of optical systems

    Science.gov (United States)

    Founds, D.

    1988-01-01

    Some of the current and planned activities at the Air Force Systems Command in structures and controls for optical-type systems are summarized. Many of the activities are contracted to industry; one task is an in-house program which includes a hardware test program. The objective of the in-house program, referred to as the Aluminum Beam Expander Structure (ABES), is to address issues involved in on-orbit system identification. The structure, which appears similar to the LDR backup structure, is about 35 feet tall. The activity to date has been limited to acquisition of about 250 hours of test data. About 30 hours of data per excitation force is gathered in order to obtain sufficient data for a good statistical estimate of the structural parameters. The development of an Integrated Structural Modeling (ISM) computer program is being done by Boeing Aerospace Company. The objective of the contracted effort is to develop a combined optics, structures, thermal, controls, and multibody dynamics simulation code.

  18. Adaptive security systems -- Combining expert systems with adaptive technologies

    Energy Technology Data Exchange (ETDEWEB)

    Argo, P.; Loveland, R.; Anderson, K. [and others

    1997-09-01

    The Adaptive Multisensor Integrated Security System (AMISS) uses a variety of computational intelligence techniques to reason from raw sensor data through an array of processing layers to arrive at an assessment for alarm/alert conditions based on human behavior within a secure facility. In this paper, the authors give an overview of the system and briefly describe some of the major components of the system. This system is currently under development and testing in a realistic facility setting.

  19. Adaptive security systems -- Combining expert systems with adaptive technologies

    International Nuclear Information System (INIS)

    Argo, P.; Loveland, R.; Anderson, K.

    1997-01-01

    The Adaptive Multisensor Integrated Security System (AMISS) uses a variety of computational intelligence techniques to reason from raw sensor data through an array of processing layers to arrive at an assessment for alarm/alert conditions based on human behavior within a secure facility. In this paper, the authors give an overview of the system and briefly describe some of the major components of the system. This system is currently under development and testing in a realistic facility setting

  20. Optical system defect propagation in ABCD systems

    DEFF Research Database (Denmark)

    McKinley, W.G.; Yura, H.T.; Hanson, Steen Grüner

    1988-01-01

    We describe how optical system defects (tilt/jitter, decenter, and despace) propagate through an arbitrary paraxial optical system that can be described by an ABCD ray transfer matrix. A pedagogical example is given that demonstrates the effect of alignment errors on a typical optical system...

  1. Adaptive fiber optics collimator based on flexible hinges.

    Science.gov (United States)

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

    2014-08-20

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

  2. Wavefront sensorless adaptive optics temporal focusing-based multiphoton microscopy.

    Science.gov (United States)

    Chang, Chia-Yuan; Cheng, Li-Chung; Su, Hung-Wei; Hu, Yvonne Yuling; Cho, Keng-Chi; Yen, Wei-Chung; Xu, Chris; Dong, Chen Yuan; Chen, Shean-Jen

    2014-06-01

    Temporal profile distortions reduce excitation efficiency and image quality in temporal focusing-based multiphoton microscopy. In order to compensate the distortions, a wavefront sensorless adaptive optics system (AOS) was integrated into the microscope. The feedback control signal of the AOS was acquired from local image intensity maximization via a hill-climbing algorithm. The control signal was then utilized to drive a deformable mirror in such a way as to eliminate the distortions. With the AOS correction, not only is the axial excitation symmetrically refocused, but the axial resolution with full two-photon excited fluorescence (TPEF) intensity is also maintained. Hence, the contrast of the TPEF image of a R6G-doped PMMA thin film is enhanced along with a 3.7-fold increase in intensity. Furthermore, the TPEF image quality of 1μm fluorescent beads sealed in agarose gel at different depths is improved.

  3. Closed loop adaptive optics for microscopy without a wavefront sensor.

    Science.gov (United States)

    Kner, Peter; Winoto, Lukman; Agard, David A; Sedat, John W

    2010-02-24

    A three-dimensional wide-field image of a small fluorescent bead contains more than enough information to accurately calculate the wavefront in the microscope objective back pupil plane using the phase retrieval technique. The phase-retrieved wavefront can then be used to set a deformable mirror to correct the point-spread function (PSF) of the microscope without the use of a wavefront sensor. This technique will be useful for aligning the deformable mirror in a widefield microscope with adaptive optics and could potentially be used to correct aberrations in samples where small fluorescent beads or other point sources are used as reference beacons. Another advantage is the high resolution of the retrieved wavefont as compared with current Shack-Hartmann wavefront sensors. Here we demonstrate effective correction of the PSF in 3 iterations. Starting from a severely aberrated system, we achieve a Strehl ratio of 0.78 and a greater than 10-fold increase in maximum intensity.

  4. Optimization-based adaptive optics for optical coherence tomography

    NARCIS (Netherlands)

    Verstraete, H.R.G.W.

    2017-01-01

    Optical coherence tomography (OCT) is a technique for non-invasive imaging based on low coherence interferometry. Its main application is found in ophthalmology, where it is used for 3D in vivo imaging of the cornea and the retina. OCT has evolved over the past decade as one of the most important

  5. Generation of optical vortices with an adaptive helical mirror.

    Science.gov (United States)

    Ghai, Devinder Pal

    2011-04-01

    Generation of optical vortices using a new design of adaptive helical mirror (AHM) is reported. The new AHM is a reflective device that can generate an optical vortex of any desired topological charge, both positive and negative, within its breakdown limits. The most fascinating feature of the AHM is that the topological charge of the optical vortex generated with it can be changed in real time by varying the excitation voltage. Generation of optical vortices up to topological charge 4 has been demonstrated. The presence of a vortex in the optical field generated with the AHM is confirmed by producing both fork and spiral fringes in an interferometric setup. Various design improvements to further enhance the performance of the reported AHM are discussed. Some of the important applications of AHM are also listed. © 2011 Optical Society of America

  6. Wavelet methods in multi-conjugate adaptive optics

    International Nuclear Information System (INIS)

    Helin, T; Yudytskiy, M

    2013-01-01

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

  7. Adaptive optics-assisted optical coherence tomography for imaging of patients with age related macular degeneration

    Science.gov (United States)

    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.

  8. Surface Plasmon Wave Adapter Designed with Transformation Optics

    DEFF Research Database (Denmark)

    Zhang, Jingjing; Xiao, Sanshui; Wubs, Martijn

    2011-01-01

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

  9. Optical pattern recognition via adaptive spatial homodyne detection.

    Science.gov (United States)

    Hsu, Magnus T L; Knittel, Joachim; Morizur, Jean-Francois; Bachor, Hans-A; Bowen, Warwick P

    2010-12-01

    We present an experimental demonstration of an optical pattern recognition scheme based on spatial homodyne detection. Our scheme is adaptive, all-optical, utilizes a single-element photo-detector, and provides a single parameter readout to quantify the efficacy of pattern recognition, thereby allowing very fast pattern recognition speeds. The spatial homodyne detector was applied to the identification of one- and two-dimensional phase profiles.

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

    Science.gov (United States)

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

    2015-01-01

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

  11. W.M. Keck Observatory Adaptive Optics Science Capabilities

    Science.gov (United States)

    Wizinowich, Peter; Campbell, R.

    2009-05-01

    Over 200 refereed science papers have been published using data from the W. M. Keck Observatory adaptive optics (AO) systems through 2008, including over 50 with the laser guide star (LGS) system. Community demand is high with 35% of the Keck II telescope science nights assigned to LGS AO and 10% to natural guide star (NGS) AO in the first half of 2009. A wide range of solar system, galactic and extragalactic science has been performed with the AO systems from weather monitoring on solar system planets and their moons, to the discovery of companions and the determination of the masses of asteroids, Kuiper Belt Objects and brown dwarfs, to measuring the fundamental properties of the black hole at the center of our galaxy, to quantifying the kinematics and morphologies of high redshift galaxies and revealing the structure of galaxies through gravitational lensing observations. The Keck AO facilities feed a variety of near to mid-infrared science instruments including an imager, a slit spectrometer, an integral field spectrometer and the Keck Interferometer. We will describe the current capabilities, performance and limitations of the AO facilities, including science instruments, with an emphasis on how this relates to the science. We will also provide a short introduction to future planned capabilities.

  12. Adaptive optics scanning laser ophthalmoscope imaging: technology update

    Directory of Open Access Journals (Sweden)

    Merino D

    2016-04-01

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

  13. Digital adaptive optics for achieving space-invariant lateral resolution in optical coherence tomography

    International Nuclear Information System (INIS)

    Kumar, A.

    2015-01-01

    Optical coherence tomography (OCT) is a non-invasive optical interferometric imaging technique that provides reflectivity profiles of the sample structures with high axial resolution. The high axial resolution is due to the use of low coherence (broad-band) light source. However, the lateral resolution in OCT depends on the numerical aperture (NA) of the focusing/imaging optics and it is affected by defocus and other higher order optical aberrations induced by the imperfect optics, or by the sample itself.Hardware based adaptive optics (AO) has been successfully combined with OCT to achieve high lateral resolution in combination with high axial resolution provided by OCT. AO, which conventionally uses Shack-Hartmann wavefront sensor (SH WFS) and deformable mirror for wavefront sensing and correction respectively, can compensate for optical aberration and can enable diffraction-limited resolution in OCT. Visualization of cone photoreceptors in 3-D has been successfully demonstrated using AO-OCT. However, OCT being an interferometric imaging technique can provide access to phase information.This phase information can be exploited by digital adaptive optics (DAO) techniques to correct optical aberration in the post-processing step to obtain diffraction-limited space invariant lateral resolution throughout the image volume. Thus, the need for hardware based AO can be eliminated, which in turn can reduce the system complexity and economical cost. In the first paper of this thesis, a novel DAO method based on sub-aperture correlation is presented which is the digital equivalent of SH WFS. The advantage of this method is that it is non-iterative in nature and it does not require a priori knowledge of any system parameters such wavelength, focal length, NA or detector pixel size. For experimental proof, a FF SS OCT system was used and the sample consisted of resolution test target and a plastic plate that introduced random optical aberration. Experimental results show that

  14. Rate Adaptive OFDMA Communication Systems

    International Nuclear Information System (INIS)

    Abdelhakim, M.M.M.

    2009-01-01

    Due to the varying nature of the wireless channels, adapting the transmission parameters, such as code rate, modulation order and power, in response to the channel variations provides a significant improvement in the system performance. In the OFDM systems, Per-Frame adaptation (PFA) can be employed where the transmission variables are fixed over a given frame and may change from one frame to the other. Subband (tile) loading offers more degrees of adaptation such that each group of carriers (subband) uses the same transmission parameters and different subbands may use different parameters. Changing the code rate for each tile in the same frame, results in transmitting multiple codewords (MCWs) for a single frame. In this thesis a scheme is proposed for adaptively changing the code rate of coded OFDMA systems via changing the puncturing rate within a single codeword (SCW). In the proposed structure, the data is encoded with the lowest available code rate then it is divided among the different tiles where it is punctured adaptively based on some measure of the channel quality for each tile. The proposed scheme is compared against using multiple codewords (MCWs) where the different code rates for the tiles are obtained using separate encoding processes. For bit interleaved coded modulation architecture two novel interleaving methods are proposed, namely the puncturing dependant interleaver (PDI) and interleaved puncturing (IntP), which provide larger interleaving depth. In the PDI method the coded bits with the same rate over different tiles are grouped for interleaving. In IntP structure the interleaving is performed prior to puncturing. The performance of the adaptive puncturing technique is investigated under constant bit rate constraint and variable bit rate. Two different adaptive modulation and coding (AMC) selection methods are examined for variable bit rate adaptive system. The first is a recursive scheme that operates directly on the SNR whereas the second

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

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  16. Nanosatellite Launch Adapter System (NLAS)

    Science.gov (United States)

    Yost, Bruce D.; Hines, John W.; Agasid, Elwood F.; Buckley, Steven J.

    2010-01-01

    The utility of small spacecraft based on the University cubesat standard is becoming evident as more and more agencies and organizations are launching or planning to include nanosatellites in their mission portfolios. Cubesats are typically launched as secondary spacecraft in enclosed, containerized deployers such as the CalPoly Poly Picosat Orbital Deployer (P-POD) system. The P-POD allows for ease of integration and significantly reduces the risk exposure to the primary spacecraft and mission. NASA/ARC and the Operationally Responsive Space office are collaborating to develop a Nanosatellite Launch Adapter System (NLAS), which can accommodate multiple cubesat or cubesat-derived spacecraft on a single launch vehicle. NLAS is composed of the adapter structure, P-POD or similar spacecraft dispensers, and a sequencer/deployer system. This paper describes the NLAS system and it s future capabilities, and also provides status on the system s development and potential first use in space.

  17. Ocean Optics Instrumentation Systems

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides instrumentation suites for a wide variety of measurements to characterize the ocean’s optical environment. These packages have been developed to...

  18. Thunder - adaptive avalanche airbag system

    OpenAIRE

    Chen, Kan

    2017-01-01

    Skiing plays an important role in outdoor activities. It allows us to regain control of our body, makes us feel alive. However, in some cases, skiing comes with great risk. Avalanche is the worth thing a skier would like to encounter. Thunder is an adaptive avalanche airbag system. Usually, an avalanche airbag product can help you float on the snow in an avalanche circumstance. Thunder are more focusing on the human behavior, making this avalanche airbag system not only an effective safety eq...

  19. Adaptive, dynamic, and resilient systems

    CERN Document Server

    Suri, Niranjan

    2015-01-01

    As the complexity of today's networked computer systems grows, they become increasingly difficult to understand, predict, and control. Addressing these challenges requires new approaches to building these systems. Adaptive, Dynamic, and Resilient Systems supplies readers with various perspectives of the critical infrastructure that systems of networked computers rely on. It introduces the key issues, describes their interrelationships, and presents new research in support of these areas.The book presents the insights of a different group of international experts in each chapter. Reporting on r

  20. Adjustment of gripping force by optical systems

    Science.gov (United States)

    Jalba, C. K.; Barz, C.

    2018-01-01

    With increasing automation, robotics also requires ever more intelligent solutions in the handling of various tasks. In this context, many grippers must also be re-designed. For this, they must always be adapted for different requirements. The equipment of the gripper systems with sensors should help to make the gripping process more intelligent. In order to achieve such objectives, optical systems can also be used. This work analyzes how the gripping force can be adjusted by means of an optical recognition. The result of this work is the creation of a connection between optical recognition, tolerances, gripping force and real-time control. In this way, algorithms can be created, with the aid of which robot grippers as well as other gripping systems become more intelligent.

  1. High Resolution Observations using Adaptive Optics: Achievements ...

    Indian Academy of Sciences (India)

    Hence, modern telescopes thrive on improving the spatial, spectral, and temporal resolutions using an AO system. It may be stated that most of the recent large solar. †NSO is operated by the Association of Universities for Research in Astronomy (AURA) under co-operative agreement with National Science Foundation ...

  2. SOUL: the Single conjugated adaptive Optics Upgrade for LBT

    Science.gov (United States)

    Pinna, E.; Esposito, S.; Hinz, P.; Agapito, G.; Bonaglia, M.; Puglisi, A.; Xompero, M.; Riccardi, A.; Briguglio, R.; Arcidiacono, C.; Carbonaro, L.; Fini, L.; Montoya, M.; Durney, O.

    2016-07-01

    We present here SOUL: the Single conjugated adaptive Optics Upgrade for LBT. Soul will upgrade the wavefront sensors replacing the existing CCD detector with an EMCCD camera and the rest of the system in order to enable the closed loop operations at a faster cycle rate and with higher number of slopes. Thanks to reduced noise, higher number of pixel and framerate, we expect a gain (for a given SR) around 1.5-2 magnitudes at all wavelengths in the range 7.5 70% in I-band and 0.6asec seeing) and the sky coverage will be multiplied by a factor 5 at all galactic latitudes. Upgrading the SCAO systems at all the 4 focal stations, SOUL will provide these benefits in 2017 to the LBTI interferometer and in 2018 to the 2 LUCI NIR spectro-imagers. In the same year the SOUL correction will be exploited also by the new generation of LBT instruments: V-SHARK, SHARK-NIR and iLocater.

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

    Science.gov (United States)

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

    2014-12-15

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

  4. Electrically controllable ionic polymeric gels as adaptive optical lenses

    Science.gov (United States)

    Salehpoor, Karim; Shahinpoor, Mohsen; Mojarrad, Mehran

    1996-02-01

    Reversible change in optical properties of ionic polymeric gels, 2-acrylamido-2-methylpropane sulfonic acid (PAMPS) and polyacrylic acid plus sodium acrylate cross-linked with bisacrylamide (PAAM), under the effect of an electric field is reported. The shape of a cylindrical piece of the gel, with flat top and bottom surfaces, changed when affected by an electric field. The top surface became curved and the sense of the curvature (whether concave or convex) depended on the polarity of the applied electric field. The curvature of the surface changed from concave to convex and vice versa by changing the polarity of the electric field. By the use of an optical apparatus, focusing capability of the curved surface was verified and the focal length of the deformed gel was measured. The effect of the intensity of the applied electric field on the surface curvature and thus, on the focal length of the gel are tested. Different mechanisms are discussed; either of them or their combination may explain the surface deformation and curvature. Practical difficulties in the test procedure and the future potential of the electrically adaptive and active optical lenses are also discussed. These adaptive lenses may be considered as smart adaptive lenses for contact lens or other optical applications requiring focal point undulation.

  5. Financial markets as adaptive systems

    Science.gov (United States)

    Potters, M.; Cont, R.; Bouchaud, J.-P.

    1998-02-01

    We show, by studying in detail the market prices of options on liquid markets, that the market has empirically corrected the simple, but inadequate Black-Scholes formula to account for two important statistical features of asset fluctuations: "fat tails" and correlations in the scale of fluctuations. These aspects, although not included in the pricing models, are very precisely reflected in the price fixed by the market as a whole. Financial markets thus behave as rather efficient adaptive systems.

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

    Science.gov (United States)

    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.

  7. Performance verification of adaptive optics for satellite-to-ground coherent optical communications at large zenith angle.

    Science.gov (United States)

    Chen, Mo; Liu, Chao; Rui, Daoman; Xian, Hao

    2018-02-19

    Although there is an urgent demand, it is still a tremendous challenge to use the coherent optical communication technology to the satellite-to-ground data transmission system especially at large zenith angle due to the influence of atmospheric turbulence. Adaptive optics (AO) is a considerable scheme to solve the problem. In this paper, we integrate the adaptive optics (AO) to the coherent laser communications and the performances of mixing efficiency as well as bit-error-rate (BER) at different zenith angles are studied. The analytical results show that the increasing of zenith angle can severely decrease the performances of the coherent detection, and increase the BER to higher than 10 -3 , which is unacceptable. The simulative results of coherent detection with AO compensation indicate that the larger mixing efficiency and lower BER can be performed by the coherent receiver with a high-mode AO compensation. The experiment of correcting the atmospheric turbulence wavefront distortion using a 249-element AO system at large zenith angles is carried out. The result demonstrates that the AO system has a significant improvement on satellite-to-ground coherent optical communication system at large zenith angle. It also indicates that the 249-element AO system can only meet the needs of coherent communication systems at zenith angle smaller than 65̊ for the 1.8m telescope under weak and moderate turbulence.

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

    OpenAIRE

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

    2008-01-01

    The purpose of this study is to understand the processes of adaptation (changes in within-trial postural responses) and habituation (reductions in between-trial postural responses) to visual cues in older and young adults. Of particular interest were responses to sudden increases in optic flow magnitude. The postural sway of 25 healthy young adults and 24 healthy older adults was measured while subjects viewed anterior-posterior 0.4 Hz sinusoidal optic flow for 45 s. Three trials for each of ...

  9. Adaptive optics confocal microscopy using direct wavefront sensing.

    Science.gov (United States)

    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.

  10. Computerized adaptive testing item selection in computerized adaptive learning systems

    NARCIS (Netherlands)

    Eggen, Theodorus Johannes Hendrikus Maria; Eggen, T.J.H.M.; Veldkamp, B.P.

    2012-01-01

    Item selection methods traditionally developed for computerized adaptive testing (CAT) are explored for their usefulness in item-based computerized adaptive learning (CAL) systems. While in CAT Fisher information-based selection is optimal, for recovering learning populations in CAL systems item

  11. Adaptive Intrusion Data System (AIDS)

    International Nuclear Information System (INIS)

    Corlis, N.E.

    1980-05-01

    The adaptive intrusion data system (AIDS) was developed to collect data from intrusion alarm sensors as part of an evaluation system to improve sensor performance. AIDS is a unique data system which uses computer controlled data systems, video cameras and recorders, analog-to-digital conversion, environmental sensors, and digital recorders to collect sensor data. The data can be viewed either manually or with a special computerized data-reduction system which adds new data to a data base stored on a magnetic disc recorder. This report provides a synoptic account of the AIDS as it presently exists. Modifications to the purchased subsystems are described, and references are made to publications which describe the Sandia-designed subsystems

  12. The use of adaptive optics for retinal imaging with microscopic resolution

    Directory of Open Access Journals (Sweden)

    Mortada A Abozaid

    2016-01-01

    Full Text Available Adaptive optics (AO is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. Adding AO to retinal imaging tools allows noninvasive direct visualization of the photoreceptor cells, capillaries, and nerve fiber bundles by correcting the eye’s monochromatic aberrations. AO can provide new information on the early pathological changes of the retinal microstructures in various retinal diseases, can also monitor response to novel treatments at the cellular level, and can help better select candidates for such treatments. This review discusses the basics, clinical applications, and challenges of AO retinal imaging.

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

    Science.gov (United States)

    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.

  14. Synergy of adaptive thresholds and multiple transmitters in free-space optical communication.

    Science.gov (United States)

    Louthain, James A; Schmidt, Jason D

    2010-04-26

    Laser propagation through extended turbulence causes severe beam spread and scintillation. Airborne laser communication systems require special considerations in size, complexity, power, and weight. Rather than using bulky, costly, adaptive optics systems, we reduce the variability of the received signal by integrating a two-transmitter system with an adaptive threshold receiver to average out the deleterious effects of turbulence. In contrast to adaptive optics approaches, systems employing multiple transmitters and adaptive thresholds exhibit performance improvements that are unaffected by turbulence strength. Simulations of this system with on-off-keying (OOK) showed that reducing the scintillation variations with multiple transmitters improves the performance of low-frequency adaptive threshold estimators by 1-3 dB. The combination of multiple transmitters and adaptive thresholding provided at least a 10 dB gain over implementing only transmitter pointing and receiver tilt correction for all three high-Rytov number scenarios. The scenario with a spherical-wave Rytov number R=0.20 enjoyed a 13 dB reduction in the required SNR for BER's between 10(-5) to 10(-3), consistent with the code gain metric. All five scenarios between 0.06 and 0.20 Rytov number improved to within 3 dB of the SNR of the lowest Rytov number scenario.

  15. Adaptive optics correction based on stochastic parallel gradient descent technique using Zernike polynomials

    Science.gov (United States)

    Ma, Huimin; Qiao, Yan; Shen, Chunshan

    2017-10-01

    Adaptive optics systems based on stochastic parallel gradient descent optimization (SPGD) have yet shown great potential on compensation of phase distortions induced by wave propagation through atmosphere turbulence. One of the key technique is increasing the converge rate of SPGD correction system. In the present study, it is shown that the convergence rate of the algorithm will be greatly reduced with the increase of the number of corrector units. In this paper, an improved SPGD optimization process which is based on Zernike-mode is developed. The optimized object is changed from the voltage to Zernike coefficient. Adaptive optics correction system simulation model base on SPGD for a laser beam projecting system, and the numerical simulation of compensation process of random atmosphere turbulence is proposed. To improve the converge speed, we explore to ameliorate the correction system by controlling the perturbation considering atmosphere aberration proportion. The results show that the system converges smoothly and increasingly after considering the aberration proportion by Zernike correction.

  16. 3D adaptive optics in a light sheet microscope.

    Science.gov (United States)

    Bourgenot, Cyril; Saunter, Christopher D; Taylor, Jonathan M; Girkin, John M; Love, Gordon D

    2012-06-04

    We report on a single plane illumination microscope (SPIM) incorporating adaptive optics in the imaging arm. We show how aberrations can occur from the sample mounting tube and quantify the aberrations both experimentally and computationally. A wavefront sensorless approach was taken to imaging a green fluorescent protein (GFP) labelled transgenic zebrafish. We show improvements in image quality whilst recording a 3D "z-stack" and show how the aberrations come from varying depths in the fish.

  17. Adaptive optics enables 3D STED microscopy in aberrating specimens.

    Science.gov (United States)

    Gould, Travis J; Burke, Daniel; Bewersdorf, Joerg; Booth, Martin J

    2012-09-10

    Stimulated emission depletion (STED) microscopy allows fluorescence far-field imaging with diffraction-unlimited resolution. Unfortunately, extending this technique to three-dimensional (3D) imaging of thick specimens has been inhibited by sample-induced aberrations. Here we present the first implementation of adaptive optics in STED microscopy to allow 3D super-resolution imaging in strongly aberrated imaging conditions, such as those introduced by thick biological tissue.

  18. Adaptive optics enables 3D STED microscopy in aberrating specimens

    Science.gov (United States)

    Gould, Travis J.; Burke, Daniel; Bewersdorf, Joerg; Booth, Martin J.

    2012-01-01

    Stimulated emission depletion (STED) microscopy allows fluorescence far-field imaging with diffraction-unlimited resolution. Unfortunately, extending this technique to three-dimensional (3D) imaging of thick specimens has been inhibited by sample-induced aberrations. Here we present the first implementation of adaptive optics in STED microscopy to allow 3D super-resolution imaging in strongly aberrated imaging conditions, such as those introduced by thick biological tissue. PMID:23037223

  19. Thermally tuneable optical modulator adapted for differential signaling

    Science.gov (United States)

    Zortman, William A.

    2016-01-12

    An apparatus for optical modulation is provided. The apparatus includes a modulator structure and a heater structure. The modulator structure comprises a ring or disk optical resonator having a closed curvilinear periphery and a pair of oppositely doped semiconductor regions within and/or adjacent to the optical resonator and conformed to modify the optical length of the optical resonator upon application of a bias voltage. The heater structure comprises a relatively resistive annulus of semiconductor material enclosed between an inner disk and an outer annulus of relatively conductive semiconductor material. The inner disk and the outer annulus are adapted as contact regions for a heater activation current. The heater structure is situated within the periphery of the optical resonator such that in operation, at least a portion of the resonator is heated by radial conductive heat flow from the heater structure. The apparatus further includes a substantially annular isolation region of dielectric or relatively resistive semiconductor material interposed between the heater structure and the modulator structure. The isolation region is effective to electrically isolate the bias voltage from the heater activation current.

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

    Science.gov (United States)

    Hansen, Anja; Krueger, Alexander; Ripken, Tammo

    2013-03-01

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

  1. Adaptive optics stochastic optical reconstruction microscopy (AO-STORM) using a genetic algorithm.

    Science.gov (United States)

    Tehrani, Kayvan F; Xu, Jianquan; Zhang, Yiwen; Shen, Ping; Kner, Peter

    2015-05-18

    The resolution of Single Molecule Localization Microscopy (SML) is dependent on the width of the Point Spread Function (PSF) and the number of photons collected. However, biological samples tend to degrade the shape of the PSF due to the heterogeneity of the index of refraction. In addition, there are aberrations caused by imperfections in the optical components and alignment, and the refractive index mismatch between the coverslip and the sample, all of which directly reduce the accuracy of SML. Adaptive Optics (AO) can play a critical role in compensating for aberrations in order to increase the resolution. However the stochastic nature of single molecule emission presents a challenge for wavefront optimization because the large fluctuations in photon emission do not permit many traditional optimization techniques to be used. Here we present an approach that optimizes the wavefront during SML acquisition by combining an intensity independent merit function with a Genetic algorithm (GA) to optimize the PSF despite the fluctuating intensity. We demonstrate the use of AO with GA in tissue culture cells and through ~50µm of tissue in the Drosophila Central Nervous System (CNS) to achieve a 4-fold increase in the localization precision.

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

    Science.gov (United States)

    Moniem, T. A.

    2016-05-01

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

  3. Towards Adaptive Spoken Dialog Systems

    CERN Document Server

    Schmitt, Alexander

    2013-01-01

    In Monitoring Adaptive Spoken Dialog Systems, authors Alexander Schmitt and Wolfgang Minker investigate statistical approaches that allow for recognition of negative dialog patterns in Spoken Dialog Systems (SDS). The presented stochastic methods allow a flexible, portable and  accurate use.  Beginning with the foundations of machine learning and pattern recognition, this monograph examines how frequently users show negative emotions in spoken dialog systems and develop novel approaches to speech-based emotion recognition using hybrid approach to model emotions. The authors make use of statistical methods based on acoustic, linguistic and contextual features to examine the relationship between the interaction flow and the occurrence of emotions using non-acted  recordings several thousand real users from commercial and non-commercial SDS. Additionally, the authors present novel statistical methods that spot problems within a dialog based on interaction patterns. The approaches enable future SDS to offer m...

  4. APPROACH TO ADAPTIVE LEARNING MANAGEMENT SYSTEM DESIGN

    Directory of Open Access Journals (Sweden)

    Vitaly A. Gaevoy

    2014-01-01

    Full Text Available In this paper, we describe how to increase the learning management systems effi ciency by using an adaptive approach. In our work we try and summarize the existing systems; the adaptability absence problem is discovered, programming and architectural adaptive learning management system designing approach is offered. 

  5. Variable Delay With Directly-Modulated R-SOA and Optical Filters for Adaptive Antenna Radio-Fiber Access

    DEFF Research Database (Denmark)

    Prince, Kamau; Presi, Marco; Chiuchiarelli, Andrea

    2009-01-01

    We present an all-optical adaptive-antenna radio over fiber transport system that uses proven, commercially-available components to effectively deliver standard-compliant optical signaling to adaptive multiantenna arrays for current and emerging radio technology implementations. The system is based...... on a directly-modulated reflective emiconductor amplifier (R-SOA) and exploits the interplay between transmission-line dispersion and tunable optical filtering to achieve flexible true time delay, with $2pi$ beam steering at the different antennas. The system was characterized, then successfully tested with two...

  6. Atmospheric Optical Communication Systems.

    Science.gov (United States)

    1981-02-01

    Johnson) Doise is given by Nt = 4kT3 (2-10) where k is Bol~ann’s coostn± and T the effective detection-systezu temperamre. (M) in lieu of specifying...34> where A. Is a coherent, complem wavebrmgiven by A13 -T ULM 4 +j (t). 2.) 17ther the wave amuplitade U, the optical ftvqiuency w , or the phase o mazy be...centered at the 4Kme 7 w - - w A’S inserted behind the detecor o remoethe uodlaed sipal elements, the lustaouu xgnal current at the 7 out~u: winl be is - (itqx

  7. Adaptive optics scanning laser ophthalmoscopy in combination with en-face optical coherence tomography

    International Nuclear Information System (INIS)

    Felberer, F.

    2014-01-01

    The human retina is a most important tissue and plays a fundamental role for the vision. Diseases of the eye affect the normal retinal function which, if untreated, may lead to vision loss or ultimately to blindness. Thus, in vivo diagnostic tools that provide detailed information on the retinal status are required in order to improve diagnosis and treatment. In recent years, several new optical imaging methods of the human retina have been developed and now represent the key part in a standard ophthalmic examination process. One of these technologies is optical coherence tomography (OCT), which provides images of the retina noninvasively and with a high axial resolution. However, imperfections of the eye's optics cause aberrations of the wavefront of the imaging light, thus limiting the transverse resolution of such systems. Improvements in the resolution of retinal images are necessary to resolve individual cells (e.g. photoreceptors) which may provide new opportunities in retinal diagnostics and therapy control. Adaptive optics (AO), a technology known from astronomy, may be used to increase image resolution. Aberrations of the imaging light are measured and corrected, resulting in an increase of lateral resolution up to the diffraction limit. Within this thesis, AO was combined with a scanning laser ophthalmoscope (SLO) that enables high resolution imaging of the retina. Measurements on healthy subjects demonstrated the ability of the system to resolve foveal cones (the smallest cone photoreceptors within the retina) and even rod photoreceptors. However, the depth resolution of the system remained limited compared to OCT instruments. Thus, in a second step, the instrument was extended to a combined AO-SLO/OCT system. The OCT system is based on transversal scanning (TS)-OCT which records en-face images of the retina and incorporates a high-speed axial eye tracking device. Together with transverse motion correction based on the AO-SLO images, the system

  8. Optical Design of Adaptive Optics Confocal Scanning Laser Ophthalmoscope with Two Deformable Mirrors.

    Science.gov (United States)

    Yang, Jinsheng; Wang, Yuanyuan; Rao, Xuejun; Wei, Ling; Li, Xiqi; He, Yi

    2017-01-01

    We describe the optical design of a confocal scanning laser ophthalmoscope with two deformable mirrors. Spherical mirrors are used for pupil relay. Defocus aberration of the human eye is corrected by a Badal focusing structure and astigmatism aberration is corrected by a deformable mirror. The main optical system achieves a diffraction-limited performance through the entire scanning field (6 mm pupil, 3 degrees on pupil plane). The performance of the optical system, with correction of defocus and astigmatism, is also evaluated.

  9. Adaptive optics in multiphoton microscopy: comparison of two, three and four photon fluorescence.

    Science.gov (United States)

    Sinefeld, David; Paudel, Hari P; Ouzounov, Dimitre G; Bifano, Thomas G; Xu, Chris

    2015-11-30

    We demonstrate adaptive optics system based on nonlinear feedback from 3- and 4-photon fluorescence. The system is based on femtosecond pulses created by soliton self-frequency shift of a 1550-nm fiber-based femtosecond laser together with micro-electro-mechanical system (MEMS) phase spatial light modulator (SLM). We perturb the 1020-segment SLM using an orthogonal Walsh sequence basis set with a modified version of three-point phase shifting interferometry. We show the improvement after aberrations correction in 3-photon signal from fluorescent beads. In addition, we compare the improvement obtained in the same adaptive optical system for 2-, 3- and 4-photon fluorescence using dye pool. We show that signal improvement resulting from aberration correction grows exponentially as a function of the order of nonlinearity.

  10. Coherent optical adaptive technique improves the spatial resolution of STED microscopy in thick samples

    Science.gov (United States)

    Yan, Wei; Yang, Yanlong; Tan, Yu; Chen, Xun; Li, Yang; Qu, Junle; Ye, Tong

    2018-01-01

    Stimulated emission depletion microscopy (STED) is one of far-field optical microscopy techniques that can provide sub-diffraction spatial resolution. The spatial resolution of the STED microscopy is determined by the specially engineered beam profile of the depletion beam and its power. However, the beam profile of the depletion beam may be distorted due to aberrations of optical systems and inhomogeneity of specimens’ optical properties, resulting in a compromised spatial resolution. The situation gets deteriorated when thick samples are imaged. In the worst case, the sever distortion of the depletion beam profile may cause complete loss of the super resolution effect no matter how much depletion power is applied to specimens. Previously several adaptive optics approaches have been explored to compensate aberrations of systems and specimens. However, it is hard to correct the complicated high-order optical aberrations of specimens. In this report, we demonstrate that the complicated distorted wavefront from a thick phantom sample can be measured by using the coherent optical adaptive technique (COAT). The full correction can effectively maintain and improve the spatial resolution in imaging thick samples. PMID:29400356

  11. Precise Prediction of Optical Performance for Near Infrared Instrument Using Adaptive Fitting Line

    Directory of Open Access Journals (Sweden)

    Kyeongyeon Ko

    2013-12-01

    Full Text Available Infrared optical systems are operated at low temperature and vacuum (LT-V condition, whereas the assembly and alignment are performed at room temperature and non-vacuum (RT-NV condition. The differences in temperature and pressure between assembly/alignment environments and operation environment change the physical characteristics of optical and opto-mechanical parts (e.g., thickness, height, length, curvature, and refractive index, and the resultant optical performance changes accordingly. In this study, using input relay optics (IO, among the components of the Immersion GRating INfrared Spectrograph (IGRINS which is an infrared spectrograph, a simulation based on the physical information of this optical system and an actual experiment were performed; and optical performances in the RT-NV, RT-V, and LT-V environments were predicted with an accuracy of 0.014±0.007 λ rms WFE, by developing an adaptive fitting line. The developed adaptive fitting line can quantitatively control assembly and alignment processes below λ/70 rms WFE. Therefore, it is expected that the subsequent processes of assembly, alignment, and performance analysis could not be repeated.

  12. Precise Prediction of Optical Performance for Near Infrared Instrument Using Adaptive Fitting Line

    Science.gov (United States)

    Ko, Kyeongyeon; Han, Jeong-Yeol; Nah, Jakyoung; Oh, Heeyoung; Yuk, In-Soo; Park, Chan; Chun, Moo-Young; Oh, Jae Sok; Kim, Kang-Min; Lee, Hanshin; Jeong, Ueejeong; Jaffe, Daniel T.

    2013-12-01

    Infrared optical systems are operated at low temperature and vacuum (LT-V) condition, whereas the assembly and alignment are performed at room temperature and non-vacuum (RT-NV) condition. The differences in temperature and pressure between assembly/alignment environments and operation environment change the physical characteristics of optical and opto-mechanical parts (e.g., thickness, height, length, curvature, and refractive index), and the resultant optical performance changes accordingly. In this study, using input relay optics (IO), among the components of the Immersion GRating INfrared Spectrograph (IGRINS) which is an infrared spectrograph, a simulation based on the physical information of this optical system and an actual experiment were performed; and optical performances in the RT-NV, RT-V, and LT-V environments were predicted with an accuracy of 0.014±0.007 λ rms WFE, by developing an adaptive fitting line. The developed adaptive fitting line can quantitatively control assembly and alignment processes below λ/70 rms WFE. Therefore, it is expected that the subsequent processes of assembly, alignment, and performance analysis could not be repeated.

  13. Coherent optical adaptive technique improves the spatial resolution of STED microscopy in thick samples.

    Science.gov (United States)

    Yan, Wei; Yang, Yanlong; Tan, Yu; Chen, Xun; Li, Yang; Qu, Junle; Ye, Tong

    2017-06-01

    Stimulated emission depletion microscopy (STED) is one of far-field optical microscopy techniques that can provide sub-diffraction spatial resolution. The spatial resolution of the STED microscopy is determined by the specially engineered beam profile of the depletion beam and its power. However, the beam profile of the depletion beam may be distorted due to aberrations of optical systems and inhomogeneity of specimens' optical properties, resulting in a compromised spatial resolution. The situation gets deteriorated when thick samples are imaged. In the worst case, the sever distortion of the depletion beam profile may cause complete loss of the super resolution effect no matter how much depletion power is applied to specimens. Previously several adaptive optics approaches have been explored to compensate aberrations of systems and specimens. However, it is hard to correct the complicated high-order optical aberrations of specimens. In this report, we demonstrate that the complicated distorted wavefront from a thick phantom sample can be measured by using the coherent optical adaptive technique (COAT). The full correction can effectively maintain and improve the spatial resolution in imaging thick samples.

  14. Superpenetration optical microscopy by iterative multiphoton adaptive compensation technique.

    Science.gov (United States)

    Tang, Jianyong; Germain, Ronald N; Cui, Meng

    2012-05-29

    Biological tissues are rarely transparent, presenting major challenges for deep tissue optical microscopy. The achievable imaging depth is fundamentally limited by wavefront distortions caused by aberration and random scattering. Here, we report an iterative wavefront compensation technique that takes advantage of the nonlinearity of multiphoton signals to determine and compensate for these distortions and to focus light inside deep tissues. Different from conventional adaptive optics methods, this technique can rapidly measure highly complicated wavefront distortions encountered in deep tissue imaging and provide compensations for not only aberration but random scattering. The technique is tested with a variety of highly heterogeneous biological samples including mouse brain tissue, skull, and lymph nodes. We show that high quality three-dimensional imaging can be realized at depths beyond the reach of conventional multiphoton microscopy and adaptive optics methods, albeit over restricted distances for a given correction. Moreover, the required laser excitation power can be greatly reduced in deep tissues, deviating from the power requirement of ballistic light excitation and thus significantly reducing photo damage to the biological tissue.

  15. Farming System Evolution and Adaptive Capacity: Insights for Adaptation Support

    Directory of Open Access Journals (Sweden)

    Jami L. Dixon

    2014-02-01

    Full Text Available Studies of climate impacts on agriculture and adaptation often provide current or future assessments, ignoring the historical contexts farming systems are situated within. We investigate how historical trends have influenced farming system adaptive capacity in Uganda using data from household surveys, semi-structured interviews, focus-group discussions and observations. By comparing two farming systems, we note three major findings: (1 similar trends in farming system evolution have had differential impacts on the diversity of farming systems; (2 trends have contributed to the erosion of informal social and cultural institutions and an increasing dependence on formal institutions; and (3 trade-offs between components of adaptive capacity are made at the farm-scale, thus influencing farming system adaptive capacity. To identify the actual impacts of future climate change and variability, it is important to recognize the dynamic nature of adaptation. In practice, areas identified for further adaptation support include: shift away from one-size-fits-all approach the identification and integration of appropriate modern farming method; a greater focus on building inclusive formal and informal institutions; and a more nuanced understanding regarding the roles and decision-making processes of influential, but external, actors. More research is needed to understand farm-scale trade-offs and the resulting impacts across spatial and temporal scales.

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

    Science.gov (United States)

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

    2017-02-01

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

  17. Aberrations and adaptive optics in super-resolution microscopy

    Science.gov (United States)

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

    2015-01-01

    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. PMID:26124194

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2015-08-01

    As one of the most powerful tools in the biological investigation of cellular structures and dynamic processes, fluorescence microscopy has undergone extraordinary developments in the past decades. The advent of super-resolution techniques has enabled fluorescence microscopy - or rather nanoscopy - to achieve nanoscale resolution in living specimens and unravelled the interior of cells with unprecedented detail. The methods employed in this expanding field of microscopy, however, are especially prone to the detrimental effects of optical aberrations. In this review, we discuss how super-resolution microscopy techniques based upon single-molecule switching, stimulated emission depletion and structured illumination each suffer from aberrations in different ways that are dependent upon intrinsic technical aspects. We discuss the use of adaptive optics as an effective means to overcome this problem. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy.

  20. Adaptive phase measurements in linear optical quantum computation

    International Nuclear Information System (INIS)

    Ralph, T C; Lund, A P; Wiseman, H M

    2005-01-01

    Photon counting induces an effective non-linear optical phase shift in certain states derived by linear optics from single photons. Although this non-linearity is non-deterministic, it is sufficient in principle to allow scalable linear optics quantum computation (LOQC). The most obvious way to encode a qubit optically is as a superposition of the vacuum and a single photon in one mode-so-called 'single-rail' logic. Until now this approach was thought to be prohibitively expensive (in resources) compared to 'dual-rail' logic where a qubit is stored by a photon across two modes. Here we attack this problem with real-time feedback control, which can realize a quantum-limited phase measurement on a single mode, as has been recently demonstrated experimentally. We show that with this added measurement resource, the resource requirements for single-rail LOQC are not substantially different from those of dual-rail LOQC. In particular, with adaptive phase measurements an arbitrary qubit state α vertical bar 0>+β vertical bar 1> can be prepared deterministically

  1. Adaptive optics multiphoton microscopy to study ex vivo ocular tissues.

    Science.gov (United States)

    Bueno, Juan M; Gualda, Emilio J; Artal, Pablo

    2010-01-01

    We develop an adaptive optics (AO) multiphoton microscope by incorporating a deformable mirror and a Hartmann-Shack wavefront sensor. The AO module operating in closed-loop is used to correct for the aberrations of the illumination laser beam. This increases the efficiency of the nonlinear processes in reducing tissue photodamage, improves contrast, and enhances lateral resolution in images of nonstained ocular tissues. In particular, the use of AO in the multiphoton microscope provides a better visualization of ocular structures, which are relevant in ophthalmology. This instrument might be useful to explore the possible connections between changes in ocular structures and the associated pathologies.

  2. Adaptive optics compensation of atmospheric turbulence: the past, the present, and the promise

    Science.gov (United States)

    Tyson, Robert K.

    1994-06-01

    An overview of adaptive optics systems development is presented with emphasis on its power to compensate for atmospheric turbulence in imaging and laser propagation. A brief history from the conceptual thinking in the 1950s through laboratory implementation in the 1970s to practical reality in the 1990s will be covered. With ongoing research to solve the problem of atmospheric anisoplanatism, the use of artificial guide stars has become as a prominent point of discussion. The understanding of the artificial guide star phenomena and advances in laser technology are bringing systems from the research and technology development mode into systems with scientific utility. Conflicting technical limitations of guide star brightness, laser psoower, and compensation spatial frequency are traded to achieve the most scientific benefit with the least cost. a summary ore recent results from operating adaptive optics systems in observatories around the world will be followed by a brief look at the future promise of adaptive optics in the commercia sector, including requirements of mass market systems for the amateur astronomer.

  3. Optical Navigation System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for a flexible navigation system for deep space operations that does not require GPS measurements. The navigation solution is computed using an...

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

    Science.gov (United States)

    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

  5. Evaluation of adaptation of ceramic inlays using optical coherence tomography and replica technique.

    Science.gov (United States)

    Ayse Gozde, Turk; Metin, Sabuncu; Mubin, Ulusoy

    2018-02-01

    Optical coherence tomography (OCT) has generally been used as a nondestructive technique to evaluate integrities of composite restorations. We investigated marginal and internal adaptations of ceramic inlay restorations with OCT and compared them to results with the silicone replica technique. Round-shaped class I cavities were prepared on 16 human maxillary first premolar teeth. Ceramic inlays were fabricated. Silicone replicas from inlays were obtained and sectioned to measure marginal and internal adaptations with a stereomicroscope (Leica Dfc 295, Bensheim, Germany). Inlays were cemented on respective teeth. Marginal and internal adaptations were then measured with the OCT system (Thorlabs, New Jersey, USA) in 200- μm intervals. Replica and OCT measurements were compared with independent samples t-tests. A paired t-test was used to evaluate the marginal and internal adaptations of each group (p inlays, whether measured by replica or OCT techniques, were within clinically acceptable limits.

  6. Femtosecond infrared intrastromal ablation and backscattering-mode adaptive-optics multiphoton microscopy in chicken corneas.

    Science.gov (United States)

    Gualda, Emilio J; Vázquez de Aldana, Javier R; Martínez-García, M Carmen; Moreno, Pablo; Hernández-Toro, Juan; Roso, Luis; Artal, Pablo; Bueno, Juan M

    2011-11-01

    The performance of femtosecond (fs) laser intrastromal ablation was evaluated with backscattering-mode adaptive-optics multiphoton microscopy in ex vivo chicken corneas. The pulse energy of the fs source used for ablation was set to generate two different ablation patterns within the corneal stroma at a certain depth. Intrastromal patterns were imaged with a custom adaptive-optics multiphoton microscope to determine the accuracy of the procedure and verify the outcomes. This study demonstrates the potential of using fs pulses as surgical and monitoring techniques to systematically investigate intratissue ablation. Further refinement of the experimental system by combining both functions into a single fs laser system would be the basis to establish new techniques capable of monitoring corneal surgery without labeling in real-time. Since the backscattering configuration has also been optimized, future in vivo implementations would also be of interest in clinical environments involving corneal ablation procedures.

  7. Optical detection in microfluidic systems

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Kutter, Jörg Peter

    2009-01-01

    Optical detection schemes continue to be favoured for measurements in microfluidic systems. A selection of the latest progress mainly within the last two years is critically reviewed. Emphasis is on integrated solutions, such as planar waveguides, coupling schemes to the outside world, evanescent...

  8. Strategic adaptation to new electoral systems

    OpenAIRE

    Selb, Peter

    2012-01-01

    How quickly, to what extent and under what conditions do voters and elites adapt to new electoral institutions in order to not waste their votes and effort on hopeless competitors? A latent-curve model of strategic adaptation is developed and fitted to district-level election data from Spain. The extent of strategic adaptation is generally found to vary with the strength of the electoral system. However, grave ethnic tensions are demonstrated to seriously retard adaptation even under favourab...

  9. Adaptive Bit Rate Video Streaming Through an RF/Free Space Optical Laser Link

    Directory of Open Access Journals (Sweden)

    A. Akbulut

    2010-06-01

    Full Text Available This paper presents a channel-adaptive video streaming scheme which adjusts video bit rate according to channel conditions and transmits video through a hybrid RF/free space optical (FSO laser communication system. The design criteria of the FSO link for video transmission to 2.9 km distance have been given and adaptive bit rate video streaming according to the varying channel state over this link has been studied. It has been shown that the proposed structure is suitable for uninterrupted transmission of videos over the hybrid wireless network with reduced packet delays and losses even when the received power is decreased due to weather conditions.

  10. SPECIAL ASPECTS OF INITIAL OPTICAL SCHEME SELECTION FOR DESIGN OF NON-IMAGING OPTICAL SYSTEMS

    Directory of Open Access Journals (Sweden)

    R. V. Anitropov

    2016-01-01

    Full Text Available Subject of Research. The research results, structural composition analysis and the parametric synthesis of the projected imaging and non-imaging optical systems were presented. We made an attempt to use the gained experience about imaging systems while designing non-imaging systems, by adapting the composition theory for the calculations of non-imaging systems. Several patterns were revealed, which provide a deeper understanding of the design process of non-imaging optical systems; measures of its optimization were proposed. Method. We investigated the applicability of the theory of composition and synthesis of non-imaging optical systems. The main provisions of the theory of composition are based on the division of all available optical elements in four types depending on their functionality, which corresponds to a modular design. Similar items were identified in non-imaging optical systems and adaptation of composition theory to their design became possible. Main Results. General design patterns of imaging and non-imaging optical systems were studied. Classification of systems, components, as well as technical and generic characteristics of imaging and non-imaging optical systems was determined. Search mechanism of the initial optical system by means of structural and parametric synthesis of non-imaging optical system was formalized. The basic elements were determined included in non-imaging systems and their classification by functionality was done. They were subdivided into basic, corrective, wide angle and high aperture ones. The rules for formation of these elements and their composition were determined: surface reflecting, refracting, spherical and nonspherical elements with total internal reflection. The foundations of composition theory for non-imaging optical systems were laid. The approbation of this method was carried out on the example of the illumination system calculation for surgical room. A 3D model of an illumination optical

  11. Fiber Optic Augmented Reality System (FOARS)

    Data.gov (United States)

    National Aeronautics and Space Administration — Innovation: Fiber Optics Augmented Reality System. This system in form of a mobile app interacts real time with the actual FOSS(Fiber Optics Sensing System) data and...

  12. Efficiency of adaptive laser emission focusing systems

    Science.gov (United States)

    Kandidov, V. P.; Chesnokov, S. S.

    The adaptive compensation for the nonlinear distortions of laser beams associated with thermal self-defocusing effects is investigated theoretically and experimentally. The principles of the modal control of the beam wave front in a class of lower optical aberrations are developed. A multicriterial control algorithm, based on an analysis of the beam image in the observation plane, is proposed and verified experimentally.

  13. Automated interferometric synthetic aperture microscopy and computational adaptive optics for improved optical coherence tomography

    OpenAIRE

    Xu, Yang; Liu, Yuan-Zhi; Boppart, Stephen A.; Carney, P. Scott

    2016-01-01

    In this paper, we introduce an algorithm framework for the automation of interferometric synthetic aperture microscopy (ISAM). Under this framework, common processing steps such as dispersion correction, Fourier domain resampling, and computational adaptive optics aberration correction are carried out as metrics-assisted parameter search problems. We further present the results of this algorithm applied to phantom and biological tissue samples and compare with manually adjusted results. With ...

  14. Modeling Power Systems as Complex Adaptive Systems

    Energy Technology Data Exchange (ETDEWEB)

    Chassin, David P.; Malard, Joel M.; Posse, Christian; Gangopadhyaya, Asim; Lu, Ning; Katipamula, Srinivas; Mallow, J V.

    2004-12-30

    Physical analogs have shown considerable promise for understanding the behavior of complex adaptive systems, including macroeconomics, biological systems, social networks, and electric power markets. Many of today's most challenging technical and policy questions can be reduced to a distributed economic control problem. Indeed, economically based control of large-scale systems is founded on the conjecture that the price-based regulation (e.g., auctions, markets) results in an optimal allocation of resources and emergent optimal system control. This report explores the state-of-the-art physical analogs for understanding the behavior of some econophysical systems and deriving stable and robust control strategies for using them. We review and discuss applications of some analytic methods based on a thermodynamic metaphor, according to which the interplay between system entropy and conservation laws gives rise to intuitive and governing global properties of complex systems that cannot be otherwise understood. We apply these methods to the question of how power markets can be expected to behave under a variety of conditions.

  15. High-speed adaptive optics line scan confocal retinal imaging for human eye.

    Science.gov (United States)

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

    2017-01-01

    Continuous and rapid eye movement causes significant intraframe distortion in adaptive optics high resolution retinal imaging. To minimize this artifact, we developed a high speed adaptive optics line scan confocal retinal imaging system. A high speed line camera was employed to acquire retinal image and custom adaptive optics was developed to compensate the wave aberration of the human eye's optics. The spatial resolution and signal to noise ratio were assessed in model eye and in living human eye. The improvement of imaging fidelity was estimated by reduction of intra-frame distortion of retinal images acquired in the living human eyes with frame rates at 30 frames/second (FPS), 100 FPS, and 200 FPS. The device produced retinal image with cellular level resolution at 200 FPS with a digitization of 512×512 pixels/frame in the living human eye. Cone photoreceptors in the central fovea and rod photoreceptors near the fovea were resolved in three human subjects in normal chorioretinal health. Compared with retinal images acquired at 30 FPS, the intra-frame distortion in images taken at 200 FPS was reduced by 50.9% to 79.7%. We demonstrated the feasibility of acquiring high resolution retinal images in the living human eye at a speed that minimizes retinal motion artifact. This device may facilitate research involving subjects with nystagmus or unsteady fixation due to central vision loss.

  16. Data-based online nonlinear extremum-seeker for wavefront sensorless adaptive optics OCT (Conference Presentation)

    Science.gov (United States)

    Jian, Yifan; Verstraete, Hans R. G. W.; Heisler, Morgan; Ju, Myeong Jin; Wahl, Daniel J.; Bliek, Laurens; Kalkman, Jeroen; Bonora, Stefano; Verhaegen, Michel; Sarunic, Marinko V.

    2017-02-01

    Adaptive optics has been successfully applied to cellular resolution imaging of the retina, enabling visualization of the characteristic mosaic patterns of the outer retina. Wavefront sensorless adaptive optics (WSAO) is a novel technique that facilitates high resolution ophthalmic imaging; it replaces the Hartmann-Shack Wavefront Sensor with an image-driven optimization algorithm and mitigates some the challenges encountered with sensor-based designs. However, WSAO generally requires longer time to perform aberrations correction than the conventional closed-loop adaptive optics. When used for in vivo retinal imaging applications, motion artifacts during the WSAO optimization process will affect the quality of the aberration correction. A faster converging optimization scheme needs to be developed to account for rapid temporal variation of the wavefront and continuously apply corrections. In this project, we investigate the Databased Online Nonlinear Extremum-seeker (DONE), a novel non-linear multivariate optimization algorithm in combination with in vivo human WSAO OCT imaging. We also report both hardware and software updates of our compact lens based WSAO 1060nm swept source OCT human retinal imaging system, including real time retinal layer segmentation and tracking (ILM and RPE), hysteresis correction for the multi-actuator adaptive lens, precise synchronization control for the 200kHz laser source, and a zoom lens unit for rapid switching of the field of view. Cross sectional images of the retinal layers and en face images of the cone photoreceptor mosaic acquired in vivo from research volunteers before and after WSAO optimization are presented.

  17. Adaptive optics compensation of orbital angular momentum beams with a modified Gerchberg-Saxton-based phase retrieval algorithm

    Science.gov (United States)

    Chang, Huan; Yin, Xiao-li; Cui, Xiao-zhou; Zhang, Zhi-chao; Ma, Jian-xin; Wu, Guo-hua; Zhang, Li-jia; Xin, Xiang-jun

    2017-12-01

    Practical orbital angular momentum (OAM)-based free-space optical (FSO) communications commonly experience serious performance degradation and crosstalk due to atmospheric turbulence. In this paper, we propose a wave-front sensorless adaptive optics (WSAO) system with a modified Gerchberg-Saxton (GS)-based phase retrieval algorithm to correct distorted OAM beams. We use the spatial phase perturbation (SPP) GS algorithm with a distorted probe Gaussian beam as the only input. The principle and parameter selections of the algorithm are analyzed, and the performance of the algorithm is discussed. The simulation results show that the proposed adaptive optics (AO) system can significantly compensate for distorted OAM beams in single-channel or multiplexed OAM systems, which provides new insights into adaptive correction systems using OAM beams.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-03-01

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

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

    Science.gov (United States)

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

    2008-01-01

    The purpose of this study is to understand the processes of adaptation (changes in within-trial postural responses) and habituation (reductions in between-trial postural responses) to visual cues in older and young adults. Of particular interest were responses to sudden increases in optic flow magnitude. The postural sway of 25 healthy young adults and 24 healthy older adults was measured while subjects viewed anterior-posterior 0.4 Hz sinusoidal optic flow for 45 s. Three trials for each of three conditions were performed: 1) constant 12 cm optic flow amplitude (24 cm peak-to-peak), 2) constant 4 cm amplitude (8 cm p-t-p), and 3) a transition in amplitude from 4 to 12 cm. The average power of head sway velocity (Pvel) was calculated for consecutive 5 s intervals during the trial to examine the changes in sway within and between trials. A mixed factor repeated measures ANOVA was performed to examine the effects of subject Group, Trial, and Interval on the Pvel. Pvel was greater in older adults in all conditions (p Pvel of the older adults decreased significantly between all 3 trials, but decreased only between trial 1 and 2 in young adults. While the responses of the young adults to the transition in optic flow from 4 to 12 cm did not significantly change, older adults had an increase in Pvel following the transition, ranging from 6.5 dB for the first trial to 3.4 dB for the third trial. These results show that older adults can habituate to repeated visual perturbation exposures; however, this habituation requires a greater number of exposures than young adults. This suggests aging impacts the ability to quickly modify the relative weighting of the sensory feedback for postural stabilization. PMID:18329878

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  1. Research on Adaptive Optics Image Restoration Algorithm by Improved Expectation Maximization Method

    OpenAIRE

    Zhang, Lijuan; Li, Dongming; Su, Wei; Yang, Jinhua; Jiang, Yutong

    2014-01-01

    To improve the effect of adaptive optics images’ restoration, we put forward a deconvolution algorithm improved by the EM algorithm which joints multiframe adaptive optics images based on expectation-maximization theory. Firstly, we need to make a mathematical model for the degenerate multiframe adaptive optics images. The function model is deduced for the points that spread with time based on phase error. The AO images are denoised using the image power spectral density and support constrain...

  2. Systems and methods for enhancing optical information

    Energy Technology Data Exchange (ETDEWEB)

    DeVore, Peter Thomas Setsuda; Chou, Jason T.

    2018-01-02

    An Optical Information Transfer Enhancer System includes a first system for producing an information bearing first optical wave that is impressed with a first information having a first information strength wherein the first optical wave has a first shape. A second system produces a second optical wave. An information strength enhancer module receives the first and said second optical waves and impresses the first optical wave upon the second optical wave via cross-phase modulation (XPM) to produce an information-strength-enhanced second optical wave having a second information strength that is greater than the first information strength of the first optical wave. Following a center-wavelength changer by an Optical Information Transfer Enhancer System improves its performance.

  3. Phase-Modulated Optical Communication Systems

    CERN Document Server

    Ho, Keang-Po

    2005-01-01

    Fiber-optic communication systems have revolutionized our telecommunication infrastructures – currently, almost all telephone land-line, cellular, and internet communications must travel via some form of optical fibers. In these transmission systems, neither the phase nor frequency of the optical signal carries information – only the intensity of the signal is used. To transmit more information in a single optical carrier, the phase of the optical carrier must be explored. As a result, there is renewed interest in phase-modulated optical communications, mainly in direct-detection DPSK signals for long-haul optical communication systems. When optical amplifiers are used to maintain certain signal level among the fiber link, the system is limited by amplifier noises and fiber nonlinearities. Phase-Modulated Optical Communication Systems surveys this newly popular area, covering the following topics: The transmitter and receiver for phase-modulated coherent lightwave systems Method for performance analysis o...

  4. Visual Cues for an Adaptive Expert System.

    Science.gov (United States)

    Miller, Helen B.

    NCR (National Cash Register) Corporation is pursuing opportunities to make their point of sale (POS) terminals easy to use and easy to learn. To approach the goal of making the technology invisible to the user, NCR has developed an adaptive expert prototype system for a department store POS operation. The structure for the adaptive system, the…

  5. Knowledge-based optical system design

    Science.gov (United States)

    Nouri, Taoufik

    1992-03-01

    This work is a new approach for the design of start optical systems and represents a new contribution of artificial intelligence techniques in the optical design field. A knowledge-based optical-systems design (KBOSD), based on artificial intelligence algorithms, first order logic, knowledge representation, rules, and heuristics on lens design, is realized. This KBOSD is equipped with optical knowledge in the domain of centered dioptrical optical systems used at low aperture and small field angles. It generates centered dioptrical, on-axis and low-aperture optical systems, which are used as start systems for the subsequent optimization by existing lens design programs. This KBOSD produces monochromatic or polychromatic optical systems, such as singlet lens, doublet lens, triplet lens, reversed singlet lens, reversed doublet lens, reversed triplet lens, and telescopes. In the design of optical systems, the KBOSD takes into account many user constraints such as cost, resistance of the optical material (glass) to chemical, thermal, and mechanical effects, as well as the optical quality such as minimal aberrations and chromatic aberrations corrections. This KBOSD is developed in the programming language Prolog and has knowledge on optical design principles and optical properties. It is composed of more than 3000 clauses. Inference engine and interconnections in the cognitive world of optical systems are described. The system uses neither a lens library nor a lens data base; it is completely based on optical design knowledge.

  6. Optical Energy Transfer and Conversion System

    Science.gov (United States)

    Stone, William C. (Inventor); Hogan, Bartholomew P. (Inventor)

    2015-01-01

    An optical power transfer system comprising a fiber spooler, a fiber optic rotary joint mechanically connected to the fiber spooler, and an electrical power extraction subsystem connected to the fiber optic rotary joint with an optical waveguide. Optical energy is generated at and transferred from a base station through fiber wrapped around the spooler, through the rotary joint, and ultimately to the power extraction system at a remote mobility platform for conversion to another form of energy.

  7. Adaptive optics retinal imaging in the living mouse eye

    Science.gov (United States)

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

    2012-01-01

    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

  8. Optical fundamentals of an adaptive substance-on-surface chemical recognizer

    Science.gov (United States)

    Fauconier, Richard; Ndoye, Mandoye; Montlouis, Webert

    2017-10-01

    The objective is to identify the chemical composition of (isotropic and homogeneous) thin liquid and gel films on various surfaces by their infrared reflectance spectra. A bistatic optical sensing concept is proposed here in which a multi-wavelength laser source and a detector are physically displaced from each other. With the aid of the concept apparatus proposed, key optical variables can be measured in real time. The variables in question (substance thickness, refractive index, etc.) are those whose un-observability causes many types of monostatic sensor (in use today) to give ambiguous identifications. Knowledge of the aforementioned key optical variables would allow an adaptive signal-processing algorithm to make unambiguous identifications of the unknown chemicals by their infrared spectra, despite their variable presentations. The proposed bistatic sensor system consists of an optical transmitter and an optical receiver. The whole system can be mounted on a stable platform. Both the optical transmitter subsystem and the optical receiver subsystem contain auxiliary sensors to determine their relative spatial positions and orientations. For each subsystem, these auxiliary sensors include an orientation sensor, and rotational sensors for absolute angular position. A profilometer-and-machine-vision subsystem is also included. An important aspect of determining the necessary optical variables is an aperture that limits the interrogatory beams to a coherent pair, rejecting those resulting from successive multiple reflections. A set of equations is developed to characterize the propagation of a coherent pair of frequency-modulated thin beams through the system. It is also shown that frequency modulation can produce easily measurable beat frequencies for determination of sample thicknesses on the order of microns to millimeters. Also shown is how the apparatus's polarization features allow it to measure the refractive index of any isotropic, homogeneous dielectric

  9. Intelligent Multimodal Signal Adaptation System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Micro Analysis and Design (MA&D) is pleased to submit this proposal to design an Intelligent Multimodal Signal Adaptation System. This system will dynamically...

  10. Digital Signal Processing for Optical Coherent Communication Systems

    DEFF Research Database (Denmark)

    Zhang, Xu

    In this thesis, digital signal processing (DSP) algorithms are studied to compensate for physical layer impairments in optical fiber coherent communication systems. The physical layer impairments investigated in this thesis include optical fiber chromatic dispersion, polarization demultiplexing......, light sources frequency and phase offset and phase noise. The studied DSP algorithms are considered as key building blocks in digital coherent receivers for the next generation of optical communication systems such as 112-Gb/s dual polarization (DP) quadrature phase shift keying (QPSK) optical...... spectrum narrowing tolerance 112-Gb/s DP-QPSK optical coherent systems using digital adaptive equalizer. The demonstrated results show that off-line DSP algorithms are able to reduce the bit error rate (BER) penalty induced by signal spectrum narrowing. Third, we also investigate bi...

  11. Improving a 1 meter telescope in order to follow giant planets in a pro-am collaboration. Next step : an affordable adaptive optic system.=

    Science.gov (United States)

    Dauvergne, J.-L.; Colas, F.; Delcroix, M.; Lecacheux, J.

    2017-09-01

    We already have very good result with the 1 meter telescope of Pic du Midi. Our goal is to have more and more people in the team in order to make a survey has long as possible of Jupiter, Uranus and Neptune. The next step is an OA system, we want to make it work on the 1 meter telescope and also make it available on the market to help other observatories to produce high resolution images of the solar system with middle size telescopes.

  12. Frequency Adaptive Control Technique for Periodic Runout and Wobble Cancellation in Optical Disk Drives

    Directory of Open Access Journals (Sweden)

    Yee-Pien Yang

    2006-10-01

    Full Text Available Periodic disturbance occurs in various applications on the control of the rotational mechanical systems. For optical disk drives, the spirally shaped tracks are usually not perfectly circular and the assembly of the disk and spindle motor is unavoidably eccentric. The resulting periodic disturbance is, therefore, synchronous with the disk rotation, and becomes particularly noticeable for the track following and focusing servo system. This paper applies a novel adaptive controller, namely Frequency Adaptive Control Technique (FACT, for rejecting the periodic runout and wobble effects in the optical disk drive with dual actuators. The control objective is to attenuate adaptively the specific frequency contents of periodic disturbances without amplifying its rest harmonics. FACT is implemented in a plug-in manner and provides a suitable framework for periodic disturbance rejection in the cases where the fundamental frequencies of the disturbance are alterable. It is shown that the convergence property of parameters in the proposed adaptive algorithm is exponentially stable. It is applicable to both the spindle modes of constant linear velocity (CLV and constant angular velocity (CAV for various operation speeds. The experiments showed that the proposed FACT has successful improvement on the tracking and focusing performance of the CD-ROM, and is extended to various compact disk drives.

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

    Science.gov (United States)

    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.

  14. Operator adaptation to changes in system reliability under adaptable automation.

    Science.gov (United States)

    Chavaillaz, Alain; Sauer, Juergen

    2017-09-01

    This experiment examined how operators coped with a change in system reliability between training and testing. Forty participants were trained for 3 h on a complex process control simulation modelling six levels of automation (LOA). In training, participants either experienced a high- (100%) or low-reliability system (50%). The impact of training experience on operator behaviour was examined during a 2.5 h testing session, in which participants either experienced a high- (100%) or low-reliability system (60%). The results showed that most operators did not often switch between LOA. Most chose an LOA that relieved them of most tasks but maintained their decision authority. Training experience did not have a strong impact on the outcome measures (e.g. performance, complacency). Low system reliability led to decreased performance and self-confidence. Furthermore, complacency was observed under high system reliability. Overall, the findings suggest benefits of adaptable automation because it accommodates different operator preferences for LOA. Practitioner Summary: The present research shows that operators can adapt to changes in system reliability between training and testing sessions. Furthermore, it provides evidence that each operator has his/her preferred automation level. Since this preference varies strongly between operators, adaptable automation seems to be suitable to accommodate these large differences.

  15. Optical Manipulation System Using a Plurality of Optical Traps

    DEFF Research Database (Denmark)

    2006-01-01

    The present invention relates to an optical manipulation system (10) for generation of a plurality of optical traps for manipulation of micro-objects including nano-objects using electromagnetic radiation forces in a micro-object manipulation volume (14), the system comprising a spatially modulat...

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

    Science.gov (United States)

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

    2011-08-15

    Early detection of axonal tissue loss in retinal nerve fiber layer (RNFL) is critical for effective treatment and management of diseases such as glaucoma. This study aims to evaluate the capability of ultrahigh-resolution optical coherence tomography with adaptive optics (UHR-AO-OCT) for imaging the RNFL axonal bundles (RNFBs) with 3×3×3μm(3) resolution in the eye. We used a research-grade UHR-AO-OCT system to acquire 3°×3° volumes in four normal subjects and one subject with an arcuate retinal nerve fiber layer defect (n=5; 29-62years). Cross section (B-scans) and en face (C-scan) slices extracted from the volumes were used to assess visibility and size distribution of individual RNFBs. In one subject, we reimaged the same RNFBs twice over a 7month interval and compared bundle width and thickness between the two imaging sessions. Lastly we compared images of an arcuate RNFL defect acquired with UHR-AO-OCT and commercial OCT (Heidelberg Spectralis). Individual RNFBs were distinguishable in all subjects at 3° retinal eccentricity in both cross-sectional and en face views (width: 30-50μm, thickness: 10-15μm). At 6° retinal eccentricity, RNFBs were distinguishable in three of the five subjects in both views (width: 30-45μm, thickness: 20-40μm). Width and thickness RNFB measurements taken 7months apart were strongly correlated (p<0.0005). Mean difference and standard deviation of the differences between the two measurement sessions were -0.1±4.0μm (width) and 0.3±1.5μm (thickness). UHR-AO-OCT outperformed commercial OCT in terms of clarity of the microscopic retina. To our knowledge, these are the first measurements of RNFB cross section reported in the living human eye. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Self-Adaptive Systems for Machine Intelligence

    CERN Document Server

    He, Haibo

    2011-01-01

    This book will advance the understanding and application of self-adaptive intelligent systems; therefore it will potentially benefit the long-term goal of replicating certain levels of brain-like intelligence in complex and networked engineering systems. It will provide new approaches for adaptive systems within uncertain environments. This will provide an opportunity to evaluate the strengths and weaknesses of the current state-of-the-art of knowledge, give rise to new research directions, and educate future professionals in this domain. Self-adaptive intelligent systems have wide application

  18. Design of control system for piezoelectric deformable mirror based on fuzzy self-adaptive PID control

    Science.gov (United States)

    Xiao, Nan; Gao, Wei; Song, Zongxi

    2017-10-01

    With the rapid development of adaptive optics technology, it is widely used in the fields of astronomical telescope imaging, laser beam shaping, optical communication and so on. As the key component of adaptive optics systems, the deformable mirror plays a role in wavefront correction. In order to achieve the high speed and high precision of deformable mirror system tracking control, it is necessary to find out the influence of each link on the system performance to model the system and design the controller. This paper presents a method about the piezoelectric deformable mirror driving control system.

  19. Acute Solar Retinopathy Imaged With Adaptive Optics, Optical Coherence Tomography Angiography, and En Face Optical Coherence Tomography.

    Science.gov (United States)

    Wu, Chris Y; Jansen, Michael E; Andrade, Jorge; Chui, Toco Y P; Do, Anna T; Rosen, Richard B; Deobhakta, Avnish

    2018-01-01

    Solar retinopathy is a rare form of retinal injury that occurs after direct sungazing. To enhance understanding of the structural changes that occur in solar retinopathy by obtaining high-resolution in vivo en face images. Case report of a young adult woman who presented to the New York Eye and Ear Infirmary with symptoms of acute solar retinopathy after viewing the solar eclipse on August 21, 2017. Results of comprehensive ophthalmic examination and images obtained by fundus photography, microperimetry, spectral-domain optical coherence tomography (OCT), adaptive optics scanning light ophthalmoscopy, OCT angiography, and en face OCT. The patient was examined after viewing the solar eclipse. Visual acuity was 20/20 OD and 20/25 OS. The patient was left-eye dominant. Spectral-domain OCT images were consistent with mild and severe acute solar retinopathy in the right and left eye, respectively. Microperimetry was normal in the right eye but showed paracentral decreased retinal sensitivity in the left eye with a central absolute scotoma. Adaptive optics images of the right eye showed a small region of nonwaveguiding photoreceptors, while images of the left eye showed a large area of abnormal and nonwaveguiding photoreceptors. Optical coherence tomography angiography images were normal in both eyes. En face OCT images of the right eye showed a small circular hyperreflective area, with central hyporeflectivity in the outer retina of the right eye. The left eye showed a hyperreflective lesion that intensified in area from inner to middle retina and became mostly hyporeflective in the outer retina. The shape of the lesion on adaptive optics and en face OCT images of the left eye corresponded to the shape of the scotoma drawn by the patient on Amsler grid. Acute solar retinopathy can present with foveal cone photoreceptor mosaic disturbances on adaptive optics scanning light ophthalmoscopy imaging. Corresponding reflectivity changes can be seen on en face OCT, especially

  20. High-Altitude Airborne Platform Characterisation of Adaptive Optic Corrected Ground Based Laser

    Science.gov (United States)

    Bennet, F.; Petkovic, M.; Sheard, B.; Greene, B.

    Adaptive optics can be used for more than astronomical imaging with large telescopes. The Research School of Astronomy and Astrophysics (RSAA) and the Space Environment Management Research Centre (SERC) at the Mount Stromlo Observatory in Canberra, Australia, have been developing adaptive optics (AO) for space environment management. Turbulence in the atmosphere causes optical signals to become degraded during propagation, which reduces the effective aperture of your transmitting or receiving telescope. An AO system measures and corrects for the turbulence in the atmosphere, allowing for greater resolution of optical signals. AO can be used to correct a laser beam propagating from the ground into space, or high-altitude airborne platform. The AO system performance depends heavily on the chosen site and system design. In order to properly design and implement a cost-effective AO system to propagate a laser into orbit, we propose using high-altitude platforms to measure AO system performance directly as a precursor in-orbit measurements. SERC plan on demonstrating remote manoeuvre of an orbiting object using photon pressure from an AO corrected high power ground based laser. The manoeuvre target will be a suitable piece of debris, or a dedicated satellite mission which is instrumented and tracked to measure the applied photon pressure and resulting orbit perturbation. High-altitude airborne platforms such as weather balloons or UAVs enable us to efficiently de-risk elements of this program by validating our numerical simulations of AO system performance with actual measurements. We are then able to confidently move towards in-orbit measurement of an AO corrected ground based laser, and remote manoeuvre with photon pressure. We present simulations along with experimental results for the development of array detectors which can be used to directly measure AO system performance.

  1. Research on Adaptive Optics Image Restoration Algorithm by Improved Expectation Maximization Method

    Directory of Open Access Journals (Sweden)

    Lijuan Zhang

    2014-01-01

    Full Text Available To improve the effect of adaptive optics images’ restoration, we put forward a deconvolution algorithm improved by the EM algorithm which joints multiframe adaptive optics images based on expectation-maximization theory. Firstly, we need to make a mathematical model for the degenerate multiframe adaptive optics images. The function model is deduced for the points that spread with time based on phase error. The AO images are denoised using the image power spectral density and support constraint. Secondly, the EM algorithm is improved by combining the AO imaging system parameters and regularization technique. A cost function for the joint-deconvolution multiframe AO images is given, and the optimization model for their parameter estimations is built. Lastly, the image-restoration experiments on both analog images and the real AO are performed to verify the recovery effect of our algorithm. The experimental results show that comparing with the Wiener-IBD or RL-IBD algorithm, our iterations decrease 14.3% and well improve the estimation accuracy. The model distinguishes the PSF of the AO images and recovers the observed target images clearly.

  2. High temporal resolution aberrometry in a 50-eye population and implications for adaptive optics error budget.

    Science.gov (United States)

    Jarosz, Jessica; Mecê, Pedro; Conan, Jean-Marc; Petit, Cyril; Paques, Michel; Meimon, Serge

    2017-04-01

    We formed a database gathering the wavefront aberrations of 50 healthy eyes measured with an original custom-built Shack-Hartmann aberrometer at a temporal frequency of 236 Hz, with 22 lenslets across a 7-mm diameter pupil, for a duration of 20 s. With this database, we draw statistics on the spatial and temporal behavior of the dynamic aberrations of the eye. Dynamic aberrations were studied on a 5-mm diameter pupil and on a 3.4 s sequence between blinks. We noted that, on average, temporal wavefront variance exhibits a n -2 power-law with radial order n and temporal spectra follow a f -1.5 power-law with temporal frequency f . From these statistics, we then extract guidelines for designing an adaptive optics system. For instance, we show the residual wavefront error evolution as a function of the number of corrected modes and of the adaptive optics loop frame rate. In particular, we infer that adaptive optics performance rapidly increases with the loop frequency up to 50 Hz, with gain being more limited at higher rates.

  3. SILDENAFIL CITRATE INDUCED RETINAL TOXICITY-ELECTRORETINOGRAM, OPTICAL COHERENCE TOMOGRAPHY, AND ADAPTIVE OPTICS FINDINGS.

    Science.gov (United States)

    Yanoga, Fatoumata; Gentile, Ronald C; Chui, Toco Y P; Freund, K Bailey; Fell, Millie; Dolz-Marco, Rosa; Rosen, Richard B

    2018-02-27

    To report a case of persistent retinal toxicity associated with a high dose of sildenafil citrate intake. Single retrospective case report. A 31-year-old white man with no medical history presented with complaints of bilateral multicolored photopsias and erythropsia (red-tinted vision), shortly after taking sildenafil citrate-purchased through the internet. Patient was found to have cone photoreceptor damage, demonstrated using electroretinogram, optical coherence tomography, and adaptive optics imaging. The patient's symptoms and the photoreceptor structural changes persisted for several months. Sildenafil citrate is a widely used erectile dysfunction medication that is typically associated with transient visual symptoms in normal dosage. At high dosage, sildenafil citrate can lead to persistent retinal toxicity in certain individuals.

  4. Stochastic parallel gradient descent based adaptive optics used for a high contrast imaging coronagraph

    International Nuclear Information System (INIS)

    Dong Bing; Ren Deqing; Zhang Xi

    2011-01-01

    An adaptive optics (AO) system based on a stochastic parallel gradient descent (SPGD) algorithm is proposed to reduce the speckle noises in the optical system of a stellar coronagraph in order to further improve the contrast. The principle of the SPGD algorithm is described briefly and a metric suitable for point source imaging optimization is given. The feasibility and good performance of the SPGD algorithm is demonstrated by an experimental system featured with a 140-actuator deformable mirror and a Hartmann-Shark wavefront sensor. Then the SPGD based AO is applied to a liquid crystal array (LCA) based coronagraph to improve the contrast. The LCA can modulate the incoming light to generate a pupil apodization mask of any pattern. A circular stepped pattern is used in our preliminary experiment and the image contrast shows improvement from 10 -3 to 10 -4.5 at an angular distance of 2λ/D after being corrected by SPGD based AO.

  5. Efficiency of adaptive laser emission focusing systems

    Energy Technology Data Exchange (ETDEWEB)

    Kandidov, V.P.; Chesnokov, S.S. (Moskovskii Gosudarstvennyi Universitet, Moscow (USSR))

    1990-01-01

    The adaptive compensation for the nonlinear distortions of laser beams associated with thermal self-defocusing effects is investigated theoretically and experimentally. The principles of the modal control of the beam wave front in a class of lower optical aberrations are developed. A multicriterial control algorithm, based on an analysis of the beam image in the observation plane, is proposed and verified experimentally. 18 refs.

  6. Automated interferometric synthetic aperture microscopy and computational adaptive optics for improved optical coherence tomography.

    Science.gov (United States)

    Xu, Yang; Liu, Yuan-Zhi; Boppart, Stephen A; Carney, P Scott

    2016-03-10

    In this paper, we introduce an algorithm framework for the automation of interferometric synthetic aperture microscopy (ISAM). Under this framework, common processing steps such as dispersion correction, Fourier domain resampling, and computational adaptive optics aberration correction are carried out as metrics-assisted parameter search problems. We further present the results of this algorithm applied to phantom and biological tissue samples and compare with manually adjusted results. With the automated algorithm, near-optimal ISAM reconstruction can be achieved without manual adjustment. At the same time, the technical barrier for the nonexpert using ISAM imaging is also significantly lowered.

  7. Evaluation of adaptation of ceramic inlays using optical coherence tomography and replica technique

    Directory of Open Access Journals (Sweden)

    TURK Ayse Gozde

    2018-02-01

    Full Text Available Abstract Optical coherence tomography (OCT has generally been used as a nondestructive technique to evaluate integrities of composite restorations. We investigated marginal and internal adaptations of ceramic inlay restorations with OCT and compared them to results with the silicone replica technique. Round-shaped class I cavities were prepared on 16 human maxillary first premolar teeth. Ceramic inlays were fabricated. Silicone replicas from inlays were obtained and sectioned to measure marginal and internal adaptations with a stereomicroscope (Leica Dfc 295, Bensheim, Germany. Inlays were cemented on respective teeth. Marginal and internal adaptations were then measured with the OCT system (Thorlabs, New Jersey, USA in 200- μm intervals. Replica and OCT measurements were compared with independent samples t-tests. A paired t-test was used to evaluate the marginal and internal adaptations of each group (p < 0.05. Marginal and internal adaptations were 100.97 ± 31.36 and 113.94 ± 39.75 μm, respectively, using the replica technique and 28.97 ± 17.86 and 97.87 ± 21.83 μm, respectively, using OCT. The differences between the techniques were significant (p = 0.00 and p = 0.01, respectively. On evaluation within the groups, internal adaptation values were found to be significantly higher than the marginal adaptation values for the replica technique (p = 0.00 and OCT (p = 0.00. Therefore, the replica and OCT techniques showed different results, with higher values of marginal and internal adaptation found with the replica technique. Marginal and internal adaptation values of ceramic inlays, whether measured by replica or OCT techniques, were within clinically acceptable limits.

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

    Science.gov (United States)

    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.

  9. HiCIAO: the Subaru Telescope's new high-contrast coronographic imager for adaptive optics

    Science.gov (United States)

    Hodapp, Klaus W.; Suzuki, Ryuji; Tamura, Motohide; Abe, Lyu; Suto, Hiroshi; Kandori, Ryo; Morino, Junichi; Nishimura, Tetsuo; Takami, Hideki; Guyon, Olivier; Jacobson, Shane; Stahlberger, Vern; Yamada, Hubert; Shelton, Richard; Hashimoto, Jun; Tavrov, Alexander; Nishikawa, Jun; Ukita, Nobuharu; Izumiura, Hideyuki; Hayashi, Masahiko; Nakajima, Tadashi; Yamada, Toru; Usuda, Tomonori

    2008-07-01

    The High-Contrast Coronographic Imager for Adaptive Optics (HiCIAO), is a coronographic simultaneous differential imager for the new 188-actuator AO system at the Subaru Telescope Nasmyth focus. It is designed primarily to search for faint companions, brown dwarves and young giant planets around nearby stars, but will also allow observations of disks around young stars and of emission line regions near other bright central sources. HiCIAO will work in conjunction with the new Subaru Telescope 188-actuator adaptive optics system. It is designed as a flexible, experimental instrument that will grow from the initial, simple coronographic system into more complex, innovative optics as these technologies become available. The main component of HiCIAO is an infrared camera optimized for spectral simultaneous differential imaging that uses a Teledyne 2.5 μm HAWAII-2RG detector array operated by a Sidecar ASIC. This paper reports on the assembly, testing, and "first light" observations at the Subaru Telescope.

  10. Second-Order Statistics for Wave Propagation through Complex Optical Systems

    DEFF Research Database (Denmark)

    Yura, H.T.; Hanson, Steen Grüner

    1989-01-01

    Closed-form expressions are derived for various statistical functions that arise in optical propagation through arbitrary optical systems that can be characterized by a complex ABCD matrix in the presence of distributed random inhomogeneities along the optical path. Specifically, within the second......-order Rytov approximation, explicit general expressions are presented for the mutual coherence function, the log-amplitude and phase correlation functions, and the mean-square irradiance that are obtained in propagation through an arbitrary paraxial ABCD optical system containing Gaussian-shaped limiting...... apertures. Additionally, we consider the performance of adaptive-optics systems through arbitrary real paraxial ABCD optical systems and derive an expression for the mean irradiance of an adaptive-optics laser transmitter through such systems. © 1989 Optical Society of America...

  11. Adaptive optics scanning laser ophthalmoscopy in fundus imaging, a review and update.

    Science.gov (United States)

    Zhang, Bing; Li, Ni; Kang, Jie; He, Yi; Chen, Xiao-Ming

    2017-01-01

    Adaptive optics scanning laser ophthalmoscopy (AO-SLO) has been a promising technique in funds imaging with growing popularity. This review firstly gives a brief history of adaptive optics (AO) and AO-SLO. Then it compares AO-SLO with conventional imaging methods (fundus fluorescein angiography, fundus autofluorescence, indocyanine green angiography and optical coherence tomography) and other AO techniques (adaptive optics flood-illumination ophthalmoscopy and adaptive optics optical coherence tomography). Furthermore, an update of current research situation in AO-SLO is made based on different fundus structures as photoreceptors (cones and rods), fundus vessels, retinal pigment epithelium layer, retinal nerve fiber layer, ganglion cell layer and lamina cribrosa. Finally, this review indicates possible research directions of AO-SLO in future.

  12. Adaptive optics scanning laser ophthalmoscopy in fundus imaging, a review and update

    Directory of Open Access Journals (Sweden)

    Bing Zhang

    2017-11-01

    Full Text Available Adaptive optics scanning laser ophthalmoscopy (AO-SLO has been a promising technique in funds imaging with growing popularity. This review firstly gives a brief history of adaptive optics (AO and AO-SLO. Then it compares AO-SLO with conventional imaging methods (fundus fluorescein angiography, fundus autofluorescence, indocyanine green angiography and optical coherence tomography and other AO techniques (adaptive optics flood-illumination ophthalmoscopy and adaptive optics optical coherence tomography. Furthermore, an update of current research situation in AO-SLO is made based on different fundus structures as photoreceptors (cones and rods, fundus vessels, retinal pigment epithelium layer, retinal nerve fiber layer, ganglion cell layer and lamina cribrosa. Finally, this review indicates possible research directions of AO-SLO in future.

  13. The ANTARES optical beacon system

    Science.gov (United States)

    Ageron, M.; Aguilar, J. A.; Albert, A.; Ameli, F.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardellier-Desages, F.; Aslanides, E.; Aubert, J.-J.; Auer, R.; Barbarito, E.; Basa, S.; Battaglieri, M.; Becherini, Y.; Beltramelli, J.; Bertin, V.; Bigi, A.; Billault, M.; Blaes, R.; de Botton, N.; Bouwhuis, M. C.; Bradbury, S. M.; Bruijn, R.; Brunner, J.; Burgio, G. F.; Busto, J.; Cafagna, F.; Caillat, L.; Calzas, A.; Capone, A.; Caponetto, L.; Carmona, E.; Carr, J.; Cartwright, S. L.; Castel, D.; Castorina, E.; Cavasinni, V.; Cecchini, S.; Ceres, A.; Charvis, P.; Chauchot, P.; Chiarusi, T.; Circella, M.; Colnard, C.; Compère, C.; Coniglione, R.; Cottini, N.; Coyle, P.; Cuneo, S.; Cussatlegras, A.-S.; Damy, G.; van Dantzig, R.; de Bonis, G.; de Marzo, C.; de Vita, R.; Dekeyser, I.; Delagnes, E.; Denans, D.; Deschamps, A.; Destelle, J.-J.; Dinkespieler, B.; Distefano, C.; Donzaud, C.; Drogou, J.-F.; Druillole, F.; Durand, D.; Ernenwein, J.-P.; Escoffier, S.; Falchini, E.; Favard, S.; Fehr, F.; Feinstein, F.; Ferry, S.; Fiorello, C.; Flaminio, V.; Fratini, K.; Fuda, J.-L.; Galeotti, S.; Gallone, J.-M.; Giacomelli, G.; Girard, N.; Gojak, C.; Goret, Ph.; Graf, K.; Hallewell, G.; Harakeh, M. N.; Hartmann, B.; Heijboer, A.; Heine, E.; Hello, Y.; Hernández-Rey, J. J.; Hößl, J.; Hoffman, C.; Hogenbirk, J.; Hubbard, J. R.; Jaquet, M.; Jaspers, M.; de Jong, M.; Jouvenot, F.; Kalantar-Nayestanaki, N.; Kappes, A.; Karg, T.; Katz, U.; Keller, P.; Kok, E.; Kok, H.; Kooijman, P.; Kopper, C.; Korolkova, E. V.; Kouchner, A.; Kretschmer, W.; Kruijer, A.; Kuch, S.; Kudryavstev, V. A.; Lagier, P.; Lahmann, R.; Lamanna, G.; Lamare, P.; Lambard, G.; Languillat, J.-C.; Laschinsky, H.; Lavalle, J.; Le Guen, Y.; Le Provost, H.; Le van Suu, A.; Lefèvre, D.; Legou, T.; Lelaizant, G.; Lim, G.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Louis, F.; Lucarelli, F.; Lyashuk, V.; Marcelin, M.; Margiotta, A.; Masullo, R.; Mazéas, F.; Mazure, A.; McMillan, J. E.; Megna, R.; Melissas, M.; Migneco, E.; Milovanovic, A.; Mongelli, M.; Montaruli, T.; Morganti, M.; Moscoso, L.; Musumeci, M.; Naumann-Godo, M.; Naumann, C.; Niess, V.; Noble, T.; Olivetto, C.; Ostasch, R.; Palanque-Delabrouille, N.; Payre, P.; Peek, H.; Perez, A.; Petta, C.; Piattelli, P.; Pillet, R.; Pineau, J.-P.; Poinsignon, J.; Popa, V.; Pradier, T.; Racca, C.; Randazzo, N.; van Randwijk, J.; Real, D.; van Rens, B.; Réthoré, F.; Rewiersma, P.; Riccobene, G.; Rigaud, V.; Ripani, M.; Roca, V.; Roda, C.; Rolin, J. F.; Rose, H. J.; Rostovtsev, A.; Roux, J.; Ruppi, M.; Russo, G. V.; Rusydi, G.; Salesa, F.; Salomon, K.; Sapienza, P.; Schmitt, F.; Schuller, J.-P.; Shanidze, R.; Sokalski, I.; Spona, T.; Spurio, M.; van der Steenhoven, G.; Stolarczyk, T.; Streeb, K.; Sulak, L.; Taiuti, M.; Tamburini, C.; Tao, C.; Terreni, G.; Thompson, L. F.; Urbano, F.; Valdy, P.; Valente, V.; Vallage, B.; Vaudaine, G.; Venekamp, G.; Verlaat, B.; Vernin, P.; de Vries-Uiterweerd, G.; van Wijk, R.; Wijnker, G.; de Witt Huberts, P.; Wobbe, G.; de Wolf, E.; Yao, A.-F.; Zaborov, D.; Zaccone, H.; Zornoza, J. D.; Zúñiga, J.

    2007-08-01

    ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It consists of a three-dimensional array of photomultiplier tubes that can detect the Cherenkov light induced by charged particles produced in the interactions of neutrinos with the surrounding medium. High angular resolution can be achieved, in particular, when a muon is produced, provided that the Cherenkov photons are detected with sufficient timing precision. Considerations of the intrinsic time uncertainties stemming from the transit time spread in the photomultiplier tubes and the mechanism of transmission of light in sea water lead to the conclusion that a relative time accuracy of the order of 0.5 ns is desirable. Accordingly, different time calibration systems have been developed for the ANTARES telescope. In this article, a system based on Optical Beacons, a set of external and well-controlled pulsed light sources located throughout the detector, is described. This calibration system takes into account the optical properties of sea water, which is used as the detection volume of the ANTARES telescope. The design, tests, construction and first results of the two types of beacons, LED and laser-based, are presented.

  14. Noninvasive optical imaging of resistance training adaptations in human muscle

    Science.gov (United States)

    Warren, Robert V.; Cotter, Joshua; Ganesan, Goutham; Le, Lisa; Agustin, Janelle P.; Duarte, Bridgette; Cutler, Kyle; O'Sullivan, Thomas; Tromberg, Bruce J.

    2017-12-01

    A quantitative and dynamic analysis of skeletal muscle structure and function can guide training protocols and optimize interventions for rehabilitation and disease. While technologies exist to measure body composition, techniques are still needed for quantitative, long-term functional imaging of muscle at the bedside. We evaluate whether diffuse optical spectroscopic imaging (DOSI) can be used for long-term assessment of resistance training (RT). DOSI measures of tissue composition were obtained from 12 adults before and after 5 weeks of training and compared to lean mass fraction (LMF) from dual-energy X-ray absorptiometry (DXA). Significant correlations were detected between DXA LMF and DOSI-measured oxy-hemo/myoglobin, deoxy-hemo/myoglobin, total-hemo/myoglobin, water, and lipid. RT-induced increases of ˜6% in oxy-hemo/myoglobin (3.4±1.0 μM, p=0.00314) and total-hemo/myoglobin (4.9±1.1 μM, p=0.00024) from the medial gastrocnemius were detected with DOSI and accompanied by ˜2% increases in lean soft tissue mass (36.4±12.4 g, p=0.01641) and ˜60% increases in 1 rep-max strength (41.5±6.2 kg, p = 1.9E-05). DOSI measures of vascular and/or muscle changes combined with correlations between DOSI and DXA suggest that quantitative diffuse optical methods can be used to evaluate body composition, provide feedback on long-term interventions, and generate new insight into training-induced muscle adaptations.

  15. Adaptation in CRISPR-Cas Systems.

    Science.gov (United States)

    Sternberg, Samuel H; Richter, Hagen; Charpentier, Emmanuelle; Qimron, Udi

    2016-03-17

    Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) proteins constitute an adaptive immune system in prokaryotes. The system preserves memories of prior infections by integrating short segments of foreign DNA, termed spacers, into the CRISPR array in a process termed adaptation. During the past 3 years, significant progress has been made on the genetic requirements and molecular mechanisms of adaptation. Here we review these recent advances, with a focus on the experimental approaches that have been developed, the insights they generated, and a proposed mechanism for self- versus non-self-discrimination during the process of spacer selection. We further describe the regulation of adaptation and the protein players involved in this fascinating process that allows bacteria and archaea to harbor adaptive immunity. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Optical engineering: understanding optical system by experiments

    Science.gov (United States)

    Scharf, Toralf

    2017-08-01

    Students have to be educated in theoretical and practical matters. Only one of them does not allow attacking complex problems in research, development, and management. After their study, students should be able to design, construct and analyze technical problems at highest levels of complexity. Who never experienced the difficulty of setting up measurements will not be able to understand, plan and manage such complex tasks in her/his future career. At EPFL a course was developed for bachelor education and is based on three pillars: concrete actions (enactive) to be done by the students, a synthesis of their work by writing a report (considered as the iconic part) and inputs from the teacher to generalize the findings and link it to a possible complete abstract description (symbolic). Intensive tutoring allowed an intermodal transfer between these categories. This EIS method originally introduced by Jerome Bruner for small children is particular well adapted for engineer education for which theoretical understanding often is not enough. The symbiosis of ex-cathedra lecture and practical work in a classroom-like situation presents an innovative step towards integrated learning that complements perfectly more abstract course principles like online courses.

  17. Phase-sensitive imaging of the outer retina using optical coherence tomography and adaptive optics.

    Science.gov (United States)

    Jonnal, Ravi S; Kocaoglu, Omer P; Wang, Qiang; Lee, Sangyeol; Miller, Donald T

    2012-01-01

    The cone photoreceptor's outer segment (OS) experiences changes in optical path length, both in response to visible stimuli and as a matter of its daily course of renewal and shedding. These changes are of interest, to quantify function in healthy cells and assess dysfunction in diseased ones. While optical coherence tomography (OCT), combined with adaptive optics (AO), has permitted unprecedented three-dimensional resolution in the living retina, it has not generally been able to measure these OS dynamics, whose scale is smaller than OCT's axial resolution of a few microns. A possible solution is to take advantage of the phase information encoded in the OCT signal. Phase-sensitive implementations of spectral-domain optical coherence tomography (SD-OCT) have been demonstrated, capable of resolving sample axial displacements much smaller than the imaging wavelength, but these have been limited to ex vivo samples. In this paper we present a novel technique for retrieving phase information from OCT volumes of the outer retina. The key component of our technique is quantification of phase differences within the retina. We provide a quantitative analysis of such phase information and show that-when combined with appropriate methods for filtering and unwrapping-it can improve the sensitivity to OS length change by more than an order of magnitude, down to 45 nm, slightly thicker than a single OS disc. We further show that phase sensitivity drops off with retinal eccentricity, and that the best location for phase imaging is close to the fovea. We apply the technique to the measurement of sub-resolution changes in the OS over matters of hours. Using custom software for registration and tracking, these microscopic changes are monitored in hundreds of cones over time. In two subjects, the OS was found to have average elongation rates of 150 nm/hr, values which agree with our previous findings. 2011 Optical Society of America

  18. Three-dimensional STED microscopy of aberrating tissue using dual adaptive optics.

    Science.gov (United States)

    Patton, Brian R; Burke, Daniel; Owald, David; Gould, Travis J; Bewersdorf, Joerg; Booth, Martin J

    2016-04-18

    When imaging through tissue, the optical inhomogeneities of the sample generate aberrations that can prevent effective Stimulated Emission Depletion (STED) imaging. This is particularly problematic for 3D-enhanced STED. We present here an adaptive optics implementation that incorporates two adaptive optic elements to enable correction in all beam paths, allowing performance improvement in thick tissue samples. We use this to demonstrate 3D STED imaging of complex structures in Drosophila melanogaster brains.

  19. Adaptive optics microscopy enhances image quality in deep layers of CLARITY processed brains of YFP-H mice

    Science.gov (United States)

    Reinig, Marc R.; Novack, Samuel W.; Tao, Xiaodong; Ermini, Florian; Bentolila, Laurent A.; Roberts, Dustin G.; MacKenzie-Graham, Allan; Godshalk, S. E.; Raven, M. A.; Kubby, Joel

    2016-03-01

    Optical sectioning of biological tissues has become the method of choice for three-dimensional histological analyses. This is particularly important in the brain were neurons can extend processes over large distances and often whole brain tracing of neuronal processes is desirable. To allow deeper optical penetration, which in fixed tissue is limited by scattering and refractive index mismatching, tissue-clearing procedures such as CLARITY have been developed. CLARITY processed brains have a nearly uniform refractive index and three-dimensional reconstructions at cellular resolution have been published. However, when imaging in deep layers at submicron resolution some limitations caused by residual refractive index mismatching become apparent, as the resulting wavefront aberrations distort the microscopic image. The wavefront can be corrected with adaptive optics. Here, we investigate the wavefront aberrations at different depths in CLARITY processed mouse brains and demonstrate the potential of adaptive optics to enable higher resolution and a better signal-to-noise ratio. Our adaptive optics system achieves high-speed measurement and correction of the wavefront with an open-loop control using a wave front sensor and a deformable mirror. Using adaptive optics enhanced microscopy, we demonstrate improved image quality wavefront, point spread function, and signal to noise in the cortex of YFP-H mice.

  20. Closed-loop adaptive optics using a spatial light modulator for sensing and compensating of optical aberrations in ophthalmic applications

    Science.gov (United States)

    Akondi, Vyas; Jewel, Md. Atikur Rahman; Vohnsen, Brian

    2014-09-01

    Sensing and compensating of optical aberrations in closed-loop mode using a single spatial light modulator (SLM) for ophthalmic applications is demonstrated. Notwithstanding the disadvantages of the SLM, in certain cases, this multitasking capability of the device makes it advantageous over existing deformable mirrors (DMs), which are expensive and in general used for aberration compensation alone. A closed-loop adaptive optics (AO) system based on a single SLM was built. Beam resizing optics were used to utilize the large active area of the device and hence make it feasible to generate 137 active subapertures for wavefront sensing. While correcting Zernike aberrations up to fourth order introduced with the help of a DM (for testing purposes), diffraction-limited resolution was achieved. It is shown that matched filter and intensity-weighted centroiding techniques stand out among others. Closed-loop wavefront correction of aberrations in backscattered light from the eyes of three healthy human subjects was demonstrated after satisfactory results were obtained using an artificial eye, which was simulated with a short focal length lens and a sheet of white paper as diffuser. It is shown that the closed-loop AO system based on a single SLM is capable of diffraction-limited correction for ophthalmic applications.

  1. High pressure fiber optic sensor system

    Science.gov (United States)

    Guida, Renato; Xia, Hua; Lee, Boon K; Dekate, Sachin N

    2013-11-26

    The present application provides a fiber optic sensor system. The fiber optic sensor system may include a small diameter bellows, a large diameter bellows, and a fiber optic pressure sensor attached to the small diameter bellows. Contraction of the large diameter bellows under an applied pressure may cause the small diameter bellows to expand such that the fiber optic pressure sensor may measure the applied pressure.

  2. Adaptive Sensor Optimization and Cognitive Image Processing Using Autonomous Optical Neuroprocessors; TOPICAL

    International Nuclear Information System (INIS)

    CAMERON, STEWART M.

    2001-01-01

    Measurement and signal intelligence demands has created new requirements for information management and interoperability as they affect surveillance and situational awareness. Integration of on-board autonomous learning and adaptive control structures within a remote sensing platform architecture would substantially improve the utility of intelligence collection by facilitating real-time optimization of measurement parameters for variable field conditions. A problem faced by conventional digital implementations of intelligent systems is the conflict between a distributed parallel structure on a sequential serial interface functionally degrading bandwidth and response time. In contrast, optically designed networks exhibit the massive parallelism and interconnect density needed to perform complex cognitive functions within a dynamic asynchronous environment. Recently, all-optical self-organizing neural networks exhibiting emergent collective behavior which mimic perception, recognition, association, and contemplative learning have been realized using photorefractive holography in combination with sensory systems for feature maps, threshold decomposition, image enhancement, and nonlinear matched filters. Such hybrid information processors depart from the classical computational paradigm based on analytic rules-based algorithms and instead utilize unsupervised generalization and perceptron-like exploratory or improvisational behaviors to evolve toward optimized solutions. These systems are robust to instrumental systematics or corrupting noise and can enrich knowledge structures by allowing competition between multiple hypotheses. This property enables them to rapidly adapt or self-compensate for dynamic or imprecise conditions which would be unstable using conventional linear control models. By incorporating an intelligent optical neuroprocessor in the back plane of an imaging sensor, a broad class of high-level cognitive image analysis problems including geometric

  3. High-resolution lidar observations of mesospheric sodium and implications for adaptive optics.

    Science.gov (United States)

    Pfrommer, Thomas; Hickson, Paul

    2010-11-01

    Observations of sodium density variability in the upper mesosphere/lower thermosphere, obtained using a high-resolution lidar system, show rapid fluctuations in the sodium centroid altitude. The temporal power spectrum extends above 1 Hz and is well-fit by a power law having a slope that is -1.95±0.12. These fluctuations produce focus errors in adaptive optics systems employing continuous-wave sodium laser guide stars, which can be significant for large-aperture telescopes. For a 30 m aperture diameter, the associated rms wavefront error is approximately 4 nm per meter of altitude change and increases as the square of the aperture diameter. The vertical velocity of the sodium centroid altitude is found to be ~23 ms(-1) on a 1 s time scale. If these high-frequency fluctuations arise primarily from advection of horizontal structure by the mesospheric wind, our data imply that variations in the sodium centroid altitude on the order of tens of meters occur over the horizontal scales spanned by proposed laser guide star asterisms. This leads to substantial differential focus errors (~107 nm over a 1 arc min separation with a 30 m aperture diameter) that may impact the performance of wide-field adaptive optics systems. Short-lasting and narrow sodium density enhancements, more than 1 order of magnitude above the local sodium density, occur due to advection of meteor trails. These have the ability to change the sodium centroid altitude by as much as 1 km in less than 1 s, which could result in temporary disruption of adaptive optics systems.

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

    DEFF Research Database (Denmark)

    Mortensen, Brian Bach

    2006-01-01

    Hybrid electro-optical packet switches utilize optics in the backplane to switch optical packets from inputs to outputs on electronic line cards. The optical packets are traditionally considerably larger than minimum size IP packets. IP packets entering the switch must be formatted (segmented) an...

  5. THREE-DIMENSIONAL ANALYSIS OF RETINAL MICROANEURYSMS WITH ADAPTIVE OPTICS OPTICAL COHERENCE TOMOGRAPHY.

    Science.gov (United States)

    Karst, Sonja G; Salas, Matthias; Hafner, Julia; Scholda, Christoph; Vogl, Wolf-Dieter; Drexler, Wolfgang; Pircher, Michael; Schmidt-Erfurth, Ursula

    2018-01-19

    To characterize retinal microaneurysms (MAs) in patients with diabetes using adaptive optics optical coherence tomography (AOOCT) and compare details found in AOOCT with those found in commercially available retinal imaging techniques. Patients with diabetes and MA in the macular area were included in this pilot study. The area of interest, identified in standard fluorescein angiography, was imaged using an AO fundus camera and AOOCT. Microaneurysms were characterized in AOOCT (visibility, reflectivity, feeding/draining vessels, and intraretinal location) and compared with findings in AO fundus camera, OCT angiography, and fluorescein angiography. Fifty-three MAs were imaged in 15 eyes of 10 patients. Feeding and/or draining vessels from both capillary plexus could be identified in 34 MAs in AOOCT images. Of 45 MAs imaged with OCT angiography, 18 (40%) were visible in the superior plexus, 12 (27%) in the deep capillary plexus, and 15 MAs (33%) could not be identified at all. Intraluminal hyperreflectivity, commonly seen in AO fundus camera, corresponded only in 8 of 27 cases (30%) to intraluminal densities seen in AOOCT. Adaptive optics OCT imaging revealed that MAs located in the inner nuclear layer were connected to the intermediate and/or deep capillary plexus. Intraluminal hyperreflectivity seen on AO fundus camera images originated from a strong reflection from the vessel wall and only in a third of the cases from intraluminal clots. Currently, AOOCT is the most expedient in vivo imaging method to capture morphologic details of retinal microvasculature in 3D and in the context of the surrounding retinal anatomy.

  6. Adaptation and timing recovery for two-dimensional optical storage

    Science.gov (United States)

    Immink, Andre H.; Riani, Jamal; van Beneden, Steven; Bergmans, Jan; Ciacci, Massimo; Nowbakht Irani, Ali; Coene, Wim; van der Lee, Alexander; Bruls, Dominique

    2004-09-01

    This paper discusses several issues related to adaptation and timing recovery for two-dimensional (2D) optical storage. In the TwoDOS format bits are stored on a 2D hexagonal lattice which is formed by recording multiple bit rows with a fixed phase relation in a so-called broad spiral or meta-spiral. Besides a large increase in data rate by reading out with multiple spots, also a density increase by a factor of two compared to Blu-ray Disc is targeted. To increase the storage density, 2D signal processing is proposed including 2D PRML detection in the form of a stripe-wise Viterbi detector. This detector introduces an increasing detection delay when going from the outer rows towards the center of the broad spiral. For fast control loops in a decision-directed mode, special measures are needed to avoid instability due to this delay. Another issue is the large span of the 2D inter-symbol interference at higher densities and tilt, leading to a large 2D equalizer. Furthermore, in case the broad spiral is recorded with a multiple-pass mastering technology (e.g. for ROM TwoDOS discs), write-channel imperfections such as time-varying lattice distortion require independent timing recovery on each row within the broad spiral.

  7. Nanomechanical characterization of adaptive optics components in microprojectors

    International Nuclear Information System (INIS)

    Palacio, Manuel; Bhushan, Bharat

    2010-01-01

    Compact microprojectors are being developed for information display in mobile electronic devices. A key component of the microprojector is the green laser package, which consists of an adaptive optics component with a drive mechanism. A crucial concern is the mechanical wear of key drive mechanism components, such as the carbon fiber reinforced polymer (CFRP) driving rod, the Zn alloy body and the stainless steel friction plate, after prolonged operation. Since friction and wear are dependent on the mechanical properties, nanoindentation experiments were conducted on these drive mechanism components using a depth-sensing nanoindenter at room and elevated temperatures up to 100 °C. The hardness and elastic modulus of all the materials studied decrease at increasing test temperatures. From plasticity index analysis, a correlation between the tendency for plastic deformation and the mechanical properties was obtained. Nanoscratch studies were also conducted in order to simulate wear, as well as examine the scratch resistance and deformation modes of these materials, where it was found that the CFRP rod exhibited the highest scratch resistance. The CFRP rod undergoes mostly brittle deformation, while the Zn alloy body and friction plate undergo plastic deformation.

  8. Deblurring adaptive optics retinal images using deep convolutional neural networks.

    Science.gov (United States)

    Fei, Xiao; Zhao, Junlei; Zhao, Haoxin; Yun, Dai; Zhang, Yudong

    2017-12-01

    The adaptive optics (AO) can be used to compensate for ocular aberrations to achieve near diffraction limited high-resolution retinal images. However, many factors such as the limited aberration measurement and correction accuracy with AO, intraocular scatter, imaging noise and so on will degrade the quality of retinal images. Image post processing is an indispensable and economical method to make up for the limitation of AO retinal imaging procedure. In this paper, we proposed a deep learning method to restore the degraded retinal images for the first time. The method directly learned an end-to-end mapping between the blurred and restored retinal images. The mapping was represented as a deep convolutional neural network that was trained to output high-quality images directly from blurry inputs without any preprocessing. This network was validated on synthetically generated retinal images as well as real AO retinal images. The assessment of the restored retinal images demonstrated that the image quality had been significantly improved.

  9. [Reproducibility of goniometry with slitlamp-adapted optical coherence tomography].

    Science.gov (United States)

    Karandish, A; Wirbelauer, C; Häberle, H; Pham, D T

    2004-06-01

    Visualization of the anterior chamber angle (ACA) is an important diagnostic part of evaluating patients with glaucoma. The purpose of this study was to evaluate the intra- and interobserver variability and reliability of the ACA and angle opening distance (AOD) measurements using optical coherence tomography (OCT). To evaluate the intra- and interobserver variability, ACA and AOD were both measured five times and in three consecutive images in 22 patients (24 eyes) by two experienced observers. The intraclass correlation coefficient (ICC) as a measure of reliability was determined to estimate the intra- and interobserver variability. The main outcome measures were accuracy, reproducibility assessed with the coefficient of variation (CV), and the limits of agreement of ACA and AOD. The intraobserver variability of five replicate measurements was +/-1.4 degrees for ACA (CV 6.2%) and +/-11 micro m for AOD (CV 4%). The ICC for the intraobserver reliability was 0.99 for both ACA and AOD. The interobserver variability of three intersessional measurements was +/-2.5 degrees for ACA (CV 10.9%) and +/-24 micro m (CV 8.3%) for AOD. The ICC was 0.95 for ACA and 0.98 for AOD. There was no difference ( p>0.05) between the two observers measuring ACA and AOD. Two-dimensional visualization of the ACA and its assessment with slitlamp-adapted OCT yielded reliable ACA and AOD measurements in a clinical setting. Thus, OCT goniometry could provide an objective method to assess the anterior chamber angle.

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

    Science.gov (United States)

    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. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  11. Optical techniques to understand biofunctional adaptation in human dentine

    Science.gov (United States)

    Kishen, Anil; Asundi, Anand K.

    2004-08-01

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

  12. Adaptive Dialogue Systems for Assistive Living Environments

    Science.gov (United States)

    Papangelis, Alexandros

    2013-01-01

    Adaptive Dialogue Systems (ADS) are intelligent systems, able to interact with users via multiple modalities, such as speech, gestures, facial expressions and others. Such systems are able to make conversation with their users, usually on a specific, narrow topic. Assistive Living Environments are environments where the users are by definition not…

  13. The Absolute Age of the Globular Cluster M15 Using Near-infrared Adaptive Optics Images from PISCES/LBT.

    NARCIS (Netherlands)

    Monelli, M.; Testa, V.; Bono, G.; Ferraro, I.; Iannicola, G.; Fiorentino, G.; Arcidiacono, C.; Massari, D.; Boutsia, K.; Briguglio, R.; Busoni, L.; Carini, R.; Close, L.; Cresci, G.; Esposito, S.; Fini, L.; Fumana, M.; Guerra, J. C.; Hill, J.; Kulesa, C.; Mannucci, F.; McCarthy, D.; Pinna, E.; Puglisi, A.; Quiros-Pacheco, F.; Ragazzoni, R.; Riccardi, A.; Skemer, A.; Xompero, M.

    2015-01-01

    We present deep near-infrared J, {K}{{s}} photometry of the old, metal-poor Galactic globular cluster M15 obtained with images collected with the LUCI1 and PISCES cameras available at the Large Binocular Telescope (LBT). We show how the use of First Light Adaptive Optics (FLAO) system coupled with

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

    Science.gov (United States)

    Chen, Diana C.; Olivier, Scot S.; Jones; Steven M.

    2010-02-23

    An adaptive optics scanning laser ophthalmoscopes is introduced to produce non-invasive views of the human retina. The use of dual deformable mirrors improved the dynamic range for correction of the wavefront aberrations compared with the use of the MEMS mirror alone, and improved the quality of the wavefront correction compared with the use of the bimorph mirror alone. The large-stroke bimorph deformable mirror improved the capability for axial sectioning with the confocal imaging system by providing an easier way to move the focus axially through different layers of the retina.

  15. Complex and Adaptive Dynamical Systems A Primer

    CERN Document Server

    Gros, Claudius

    2011-01-01

    We are living in an ever more complex world, an epoch where human actions can accordingly acquire far-reaching potentialities. Complex and adaptive dynamical systems are ubiquitous in the world surrounding us and require us to adapt to new realities and the way of dealing with them. This primer has been developed with the aim of conveying a wide range of "commons-sense" knowledge in the field of quantitative complex system science at an introductory level, providing an entry point to this both fascinating and vitally important subject. The approach is modular and phenomenology driven. Examples of emerging phenomena of generic importance treated in this book are: -- The small world phenomenon in social and scale-free networks. -- Phase transitions and self-organized criticality in adaptive systems. -- Life at the edge of chaos and coevolutionary avalanches resulting from the unfolding of all living. -- The concept of living dynamical systems and emotional diffusive control within cognitive system theory. Techn...

  16. Complex and adaptive dynamical systems a primer

    CERN Document Server

    Gros, Claudius

    2007-01-01

    We are living in an ever more complex world, an epoch where human actions can accordingly acquire far-reaching potentialities. Complex and adaptive dynamical systems are ubiquitous in the world surrounding us and require us to adapt to new realities and the way of dealing with them. This primer has been developed with the aim of conveying a wide range of "commons-sense" knowledge in the field of quantitative complex system science at an introductory level, providing an entry point to this both fascinating and vitally important subject. The approach is modular and phenomenology driven. Examples of emerging phenomena of generic importance treated in this book are: -- The small world phenomenon in social and scale-free networks. -- Phase transitions and self-organized criticality in adaptive systems. -- Life at the edge of chaos and coevolutionary avalanches resulting from the unfolding of all living. -- The concept of living dynamical systems and emotional diffusive control within cognitive system theory. Techn...

  17. Adaptive processes in economic systems

    CERN Document Server

    Murphy, Roy E

    1965-01-01

    In this book, we study theoretical and practical aspects of computing methods for mathematical modelling of nonlinear systems. A number of computing techniques are considered, such as methods of operator approximation with any given accuracy; operator interpolation techniques including a non-Lagrange interpolation; methods of system representation subject to constraints associated with concepts of causality, memory and stationarity; methods of system representation with an accuracy that is the best within a given class of models; methods of covariance matrix estimation;. methods for low-rank m

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

    Science.gov (United States)

    Close, Laird M.

    2016-07-01

    We review astronomical results in the visible (λsystem (Baranec, et al. 2016) on the robotic Palomar D=1.5 m telescope (currently relocated to the Kitt Peak 1.8m; Salama et al. 2016). Robo-AO uniquely offers the ability to target >15 objects/hr, which has enabled large (>3000 discrete targets) companion star surveys and has resulted in 23 refereed science publications. The most productive large telescope visible AO system is the D=6.5m Magellan telescope AO system (MagAO). MagAO is an advanced Adaptive Secondary Mirror (ASM) AO system at the Magellan 6.5m in Chile (Morzinski et al. 2016). This ASM secondary has 585 actuators with system (Fusco et al. 2016). ZIMPOL's ability to differentiate scattered polarized light from starlight allows the sensitive detection of circumstellar disks, stellar surfaces, and envelopes of evolved AGB stars. Here we review the key steps to having good performance in the visible and review the exciting new AO visible science opportunities and science results in the fields of: exoplanet detection; circumstellar and protoplanetary disks; young stars; AGB stars; emission line jets; and stellar surfaces. The recent rapid increase in the scientific publications and power of visible AO is due to the maturity of the next-generation of AO systems and our new ability probe circumstellar regions with very high (10-30 mas) spatial resolutions that would otherwise require much larger (>10m) diameter telescopes in the infrared.

  19. Fast correction approach for wavefront sensorless adaptive optics based on a linear phase diversity technique.

    Science.gov (United States)

    Yue, Dan; Nie, Haitao; Li, Ye; Ying, Changsheng

    2018-03-01

    Wavefront sensorless (WFSless) adaptive optics (AO) systems have been widely studied in recent years. To reach optimum results, such systems require an efficient correction method. This paper presents a fast wavefront correction approach for a WFSless AO system mainly based on the linear phase diversity (PD) technique. The fast closed-loop control algorithm is set up based on the linear relationship between the drive voltage of the deformable mirror (DM) and the far-field images of the system, which is obtained through the linear PD algorithm combined with the influence function of the DM. A large number of phase screens under different turbulence strengths are simulated to test the performance of the proposed method. The numerical simulation results show that the method has fast convergence rate and strong correction ability, a few correction times can achieve good correction results, and can effectively improve the imaging quality of the system while needing fewer measurements of CCD data.

  20. Holographic line field en-face OCT with digital adaptive optics in the retinain vivo.

    Science.gov (United States)

    Ginner, Laurin; Schmoll, Tilman; Kumar, Abhishek; Salas, Matthias; Pricoupenko, Nastassia; Wurster, Lara M; Leitgeb, Rainer A

    2018-02-01

    We demonstrate a high-resolution line field en-face time domain optical coherence tomography (OCT) system using an off-axis holography configuration. Line field en-face OCT produces high speed en-face images at rates of up to 100 Hz. The high frame rate favors good phase stability across the lateral field-of-view which is indispensable for digital adaptive optics (DAO). Human retinal structures are acquired in-vivo with a broadband light source at 840 nm, and line rates of 10 kHz to 100 kHz. Structures of different retinal layers, such as photoreceptors, capillaries, and nerve fibers are visualized with high resolution of 2.8 µm and 5.5 µm in lateral directions. Subaperture based DAO is successfully applied to increase the visibility of cone-photoreceptors and nerve fibers. Furthermore, en-face Doppler OCT maps are generated based on calculating the differential phase shifts between recorded lines.

  1. Digital optical feeder links system for broadband geostationary satellite

    Science.gov (United States)

    Poulenard, Sylvain; Mège, Alexandre; Fuchs, Christian; Perlot, Nicolas; Riedi, Jerome; Perdigues, Josep

    2017-02-01

    An optical link based on a multiplex of wavelengths at 1.55μm is foreseen to be a valuable solution for the feeder link of the next generation of high-throughput geostationary satellite. The main satellite operator specifications for such link are an availability of 99.9% over the year, a capacity around 500Gbit/s and to be bent-pipe. Optical ground station networks connected to Terabit/s terrestrial fibers are proposed. The availability of the optical feeder link is simulated over 5 years based on a state-of-the-art cloud mask data bank and an atmospheric turbulence strength model. Yearly and seasonal optical feeder link availabilities are derived and discussed. On-ground and on-board terminals are designed to be compliant with 10Gbit/s per optical channel data rate taking into account adaptive optic systems to mitigate the impact of atmospheric turbulences on single-mode optical fiber receivers. The forward and return transmission chains, concept and implementation, are described. These are based on a digital transparent on-off keying optical link with digitalization of the DVB-S2 and DVB-RCS signals prior to the transmission, and a forward error correcting code. In addition, the satellite architecture is described taking into account optical and radiofrequency payloads as well as their interfaces.

  2. Astrometric and photometric measurements of binary stars with adaptive optics: observations from 2001 to 2006

    Science.gov (United States)

    Roberts, Lewis C.; Mason, Brian D.

    2018-02-01

    The adaptive optics system at the 3.6 m Advanced Electro-Optical System telescope was used to measure the astrometry and differential magnitude in I band of binary star systems between 2002 and 2006. We report 413 astrometric and photometric measurements of 373 stellar pairs. The astrometric measurements will be of use for future orbital determination, and the photometric measurements will be of use in estimating the spectral types of the component stars. For 21 binaries that had not been observed in decades, we are able to confirm that the systems share common proper motion. Candidate new companions were detected in 24 systems; for these we show the discovery images. Follow-up observations should be able to determine if these systems share common proper motion and are gravitationally bound objects. We computed orbits for nine binaries. Of these, the orbits of five systems are improved compared to prior orbits and four systems have their orbits computed for the first time. In addition, 315 stars were unresolved and the full-width half maxima of the images are presented.

  3. Preliminary images from an adaptive imaging system

    NARCIS (Netherlands)

    Griffiths, J.A.; Metaxas, M.G.; Pani, S.; Schulerud, H.; Esbrand, C.; Royle, G.J.; Price, B.; Rokvic, T.; Longo, R.; Asimidis, A.; Bletsas, E.; Cavouras, D.; Fant, A.; Gasiorek, P.; Georgiou, H.; Hall, G.; Jones, J.; Leaver, J.; Li, G.; Machin, D.; Manthos, N.; Matheson, J.; Noy, M.; Østby, J.M.; Psomadellis, F.; van der Stelt, P.F.; Theodoridis, S.; Triantis, F.; Turchetta, R.; Venanzi, C.; Speller, R.D.

    2008-01-01

    I-ImaS (Intelligent Imaging Sensors) is a European project aiming to produce real-time adaptive X-ray imaging systems using Monolithic Active Pixel Sensors (MAPS) to create images with maximum diagnostic information within given dose constraints. Initial systems concentrate on mammography and

  4. Simple adaptive control system design trades

    NARCIS (Netherlands)

    Mooij, E.

    2017-01-01

    In the design of a Model Reference Adaptive Control system, a reference model serves as the (well-known) basis through which system and user requirements can find their way into the design. By tuning the design parameters, the response of the actual vehicle should track the response of the

  5. Adaptation in the auditory system: an overview

    Directory of Open Access Journals (Sweden)

    David ePérez-González

    2014-02-01

    Full Text Available The early stages of the auditory system need to preserve the timing information of sounds in order to extract the basic features of acoustic stimuli. At the same time, different processes of neuronal adaptation occur at several levels to further process the auditory information. For instance, auditory nerve fiber responses already experience adaptation of their firing rates, a type of response that can be found in many other auditory nuclei and may be useful for emphasizing the onset of the stimuli. However, it is at higher levels in the auditory hierarchy where more sophisticated types of neuronal processing take place. For example, stimulus-specific adaptation, where neurons show adaptation to frequent, repetitive stimuli, but maintain their responsiveness to stimuli with different physical characteristics, thus representing a distinct kind of processing that may play a role in change and deviance detection. In the auditory cortex, adaptation takes more elaborate forms, and contributes to the processing of complex sequences, auditory scene analysis and attention. Here we review the multiple types of adaptation that occur in the auditory system, which are part of the pool of resources that the neurons employ to process the auditory scene, and are critical to a proper understanding of the neuronal mechanisms that govern auditory perception.

  6. Managing adaptively for multifunctionality in agricultural systems.

    Science.gov (United States)

    Hodbod, Jennifer; Barreteau, Olivier; Allen, Craig; Magda, Danièle

    2016-12-01

    The critical importance of agricultural systems for food security and as a dominant global landcover requires management that considers the full dimensions of system functions at appropriate scales, i.e. multifunctionality. We propose that adaptive management is the most suitable management approach for such goals, given its ability to reduce uncertainty over time and support multiple objectives within a system, for multiple actors. As such, adaptive management may be the most appropriate method for sustainably intensifying production whilst increasing the quantity and quality of ecosystem services. However, the current assessment of performance of agricultural systems doesn't reward ecosystem service provision. Therefore, we present an overview of the ecosystem functions agricultural systems should and could provide, coupled with a revised definition for assessing the performance of agricultural systems from a multifunctional perspective that, when all satisfied, would create adaptive agricultural systems that can increase production whilst ensuring food security and the quantity and quality of ecosystem services. The outcome of this high level of performance is the capacity to respond to multiple shocks without collapse, equity and triple bottom line sustainability. Through the assessment of case studies, we find that alternatives to industrialized agricultural systems incorporate more functional goals, but that there are mixed findings as to whether these goals translate into positive measurable outcomes. We suggest that an adaptive management perspective would support the implementation of a systematic analysis of the social, ecological and economic trade-offs occurring within such systems, particularly between ecosystem services and functions, in order to provide suitable and comparable assessments. We also identify indicators to monitor performance at multiple scales in agricultural systems which can be used within an adaptive management framework to increase

  7. Managing adaptively for multifunctionality in agricultural systems

    Science.gov (United States)

    Hodbod, Jennifer; Barreteau, Olivier; Allen, Craig R.; Magda, Danièle

    2016-01-01

    The critical importance of agricultural systems for food security and as a dominant global landcover requires management that considers the full dimensions of system functions at appropriate scales, i.e. multifunctionality. We propose that adaptive management is the most suitable management approach for such goals, given its ability to reduce uncertainty over time and support multiple objectives within a system, for multiple actors. As such, adaptive management may be the most appropriate method for sustainably intensifying production whilst increasing the quantity and quality of ecosystem services. However, the current assessment of performance of agricultural systems doesn’t reward ecosystem service provision. Therefore, we present an overview of the ecosystem functions agricultural systems should and could provide, coupled with a revised definition for assessing the performance of agricultural systems from a multifunctional perspective that, when all satisfied, would create adaptive agricultural systems that can increase production whilst ensuring food security and the quantity and quality of ecosystem services. The outcome of this high level of performance is the capacity to respond to multiple shocks without collapse, equity and triple bottom line sustainability. Through the assessment of case studies, we find that alternatives to industrialized agricultural systems incorporate more functional goals, but that there are mixed findings as to whether these goals translate into positive measurable outcomes. We suggest that an adaptive management perspective would support the implementation of a systematic analysis of the social, ecological and economic trade-offs occurring within such systems, particularly between ecosystem services and functions, in order to provide suitable and comparable assessments. We also identify indicators to monitor performance at multiple scales in agricultural systems which can be used within an adaptive management framework to

  8. Weekly Glacier Flow Estimation from Dense Satellite Time Series Using Adapted Optical Flow Technology

    Directory of Open Access Journals (Sweden)

    Bas Altena

    2017-06-01

    Full Text Available Contemporary optical remote sensing satellites or constellations of satellites can acquire imagery at sub-weekly or even daily timescales. These systems have the potential to facilitate intra-seasonal, short-term surface velocity variations across a range of ice masses. Current techniques for displacement estimation are based on matching image pairs with sufficient displacement and/or preservation of the surface over time and consequently, do not benefit from an increase in satellite revisit times. Here, we explore an approach that is fundamentally different from image correlation or similar approaches and engages the concept of optical flow. Our goal is to assess whether this technique could overcome the limitations of image matching and yield new insights in glacier flow dynamics. We implement two different methods of optical flow, and test these implementations utilizing the SPOT5 Take5 dataset at two glaciers: Kronebreen, Svalbard and Kaskawulsh Glacier, Yukon. At Kaskawulsh Glacier, we extract intra-seasonal velocity variations that are synchronous with episodes of increased air temperature. Moreover, even for the cloudy dataset of Kronebreen, we can extract spatio-temporal trajectories that correlate well with measured GPS flow paths. Since the underlying concept is simple and computationally efficient due to data-reduction, our optical flow methodology can be rapidly adapted for a range of studies from the investigation of large scale ice sheet dynamics down to the estimation of displacements over small and slow flowing glaciers.

  9. Evolving Systems and Adaptive Key Component Control

    Science.gov (United States)

    Frost, Susan A.; Balas, Mark J.

    2009-01-01

    We propose a new framework called Evolving Systems to describe the self-assembly, or autonomous assembly, of actively controlled dynamical subsystems into an Evolved System with a higher purpose. An introduction to Evolving Systems and exploration of the essential topics of the control and stability properties of Evolving Systems is provided. This chapter defines a framework for Evolving Systems, develops theory and control solutions for fundamental characteristics of Evolving Systems, and provides illustrative examples of Evolving Systems and their control with adaptive key component controllers.

  10. Experimental demonstration of single-mode fiber coupling over relatively strong turbulence with adaptive optics.

    Science.gov (United States)

    Chen, Mo; Liu, Chao; Xian, Hao

    2015-10-10

    High-speed free-space optical communication systems using fiber-optic components can greatly improve the stability of the system and simplify the structure. However, propagation through atmospheric turbulence degrades the spatial coherence of the signal beam and limits the single-mode fiber (SMF) coupling efficiency. In this paper, we analyze the influence of the atmospheric turbulence on the SMF coupling efficiency over various turbulences. The results show that the SMF coupling efficiency drops from 81% without phase distortion to 10% when phase root mean square value equals 0.3λ. The simulations of SMF coupling with adaptive optics (AO) indicate that it is inevitable to compensate the high-order aberrations for SMF coupling over relatively strong turbulence. The SMF coupling efficiency experiments, using an AO system with a 137-element deformable mirror and a Hartmann-Shack wavefront sensor, obtain average coupling efficiency increasing from 1.3% in open loop to 46.1% in closed loop under a relatively strong turbulence, D/r0=15.1.

  11. New Photonic System for Optical Packet Switching

    Directory of Open Access Journals (Sweden)

    F. Rudge Barbosa

    2003-08-01

    Full Text Available Fast optical switching (ms timebase is realized by using a RF frequency tone inserted in the optical packet that carries a digital payload. By using a highly selective RF filtering for optical packet header frequency recognition, we have obtained excellent performance in optical switching function.. The RF header is detected at optical node input, and signals the node switching control, which instantly directs the packet to a prescribed output. No electronic processing of the digital payload is performed. The optical circuit is noise-free, has very low crosstalk, and is extremely selective in header frequency detection. BER measurements for payload consistently yield figures as low as 10-12 . This system is applicable to optical metropolitan and access networks, and is fully compatible with DWDM systems.

  12. Optimized systems for energy efficient optical tweezing

    Science.gov (United States)

    Kampmann, R.; Kleindienst, R.; Grewe, A.; Bürger, Elisabeth; Oeder, A.; Sinzinger, S.

    2013-03-01

    Compared to conventional optics like singlet lenses or even microscope objectives advanced optical designs help to develop properties specifically useful for efficient optical tweezers. We present an optical setup providing a customized intensity distribution optimized with respect to large trapping forces. The optical design concept combines a refractive double axicon with a reflective parabolic focusing mirror. The axicon arrangement creates an annular field distribution and thus clears space for additional integrated observation optics in the center of the system. Finally the beam is focused to the desired intensity distribution by a parabolic ring mirror. The compact realization of the system potentially opens new fields of applications for optical tweezers such as in production industries and micro-nano assembly.

  13. IMAGING WITH MULTIMODAL ADAPTIVE-OPTICS OPTICAL COHERENCE TOMOGRAPHY IN MULTIPLE EVANESCENT WHITE DOT SYNDROME: THE STRUCTURE AND FUNCTIONAL RELATIONSHIP.

    Science.gov (United States)

    Labriola, Leanne T; 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

    To elucidate the location of pathological changes in multiple evanescent white dot syndrome (MEWDS) with the use of multimodal adaptive optics (AO) imaging. 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. 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. 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.

  14. Astrophysical Adaptation of Points, the Precision Optical Interferometer in Space

    Science.gov (United States)

    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

  15. Silicon retina for optical tracking systems

    Science.gov (United States)

    Strohbehn, K.; Jenkins, R. E.; Sun, X.; Andreou, A. G.

    1993-01-01

    There are a host of position sensors, such as quadcells and CCD's, which are candidates for detecting optical position errors and providing error signals for a mirror positioning loop. We are developing a novel, very high bandwidth, biologically inspired position sensor for optical position tracking systems. We present recent test results and design issues for the use of biologically inspired silicon retinas for spaceborne optical position tracking systems.

  16. Adaptive control of solar energy collector systems

    CERN Document Server

    Lemos, João M; Igreja, José M

    2014-01-01

    This book describes methods for adaptive control of distributed-collector solar fields: plants that collect solar energy and deliver it in thermal form. Controller design methods are presented that can overcome difficulties found in these type of plants:they are distributed-parameter systems, i.e., systems with dynamics that depend on space as well as time;their dynamics is nonlinear, with a bilinear structure;there is a significant level of uncertainty in plant knowledge.Adaptive methods form the focus of the text because of the degree of uncertainty in the knowledge of plant dynamics. Parts

  17. Hot dust in the active nucleus of NGC 7469 probed by adaptive optics observations

    Science.gov (United States)

    Marco, O.; Alloin, D.

    1998-08-01

    The use of adaptive optics has allowed to reach in the infrared an angular resolution around 0.35'', allowing to study the temperature, mass and distribution of the dust component within the 400 pc radius central region of \

  18. Adaptive fuzzy system for 3-D vision

    Science.gov (United States)

    Mitra, Sunanda

    1993-01-01

    An adaptive fuzzy system using the concept of the Adaptive Resonance Theory (ART) type neural network architecture and incorporating fuzzy c-means (FCM) system equations for reclassification of cluster centers was developed. The Adaptive Fuzzy Leader Clustering (AFLC) architecture is a hybrid neural-fuzzy system which learns on-line in a stable and efficient manner. The system uses a control structure similar to that found in the Adaptive Resonance Theory (ART-1) network to identify the cluster centers initially. The initial classification of an input takes place in a two stage process; a simple competitive stage and a distance metric comparison stage. The cluster prototypes are then incrementally updated by relocating the centroid positions from Fuzzy c-Means (FCM) system equations for the centroids and the membership values. The operational characteristics of AFLC and the critical parameters involved in its operation are discussed. The performance of the AFLC algorithm is presented through application of the algorithm to the Anderson Iris data, and laser-luminescent fingerprint image data. The AFLC algorithm successfully classifies features extracted from real data, discrete or continuous, indicating the potential strength of this new clustering algorithm in analyzing complex data sets. The hybrid neuro-fuzzy AFLC algorithm will enhance analysis of a number of difficult recognition and control problems involved with Tethered Satellite Systems and on-orbit space shuttle attitude controller.

  19. Environmentally-adapted local energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Moe, N.; Oefverholm, E. [NUTEK, Stockholm (Sweden); Andersson, Owe [EKAN Gruppen (Sweden); Froste, H. [Swedish Environmental Protection Agency, Stockholm (Sweden)

    1997-10-01

    Energy companies, municipalities, property companies, firms of consultants, environmental groups and individuals are examples of players working locally to shape environmentally adapted energy systems. These players have needed information making them better able to make decisions on cost-efficient, environmentally-adapted energy systems. This book answers many of the questions they have put. The volume is mainly based on Swedish handbooks produced by the Swedish National Board for Industrial and Technical Development, NUTEK, together with the Swedish Environmental Protection Agency. These handbooks have been used in conjunction with municipal energy planning, local Agenda 21 work, to provide a basis for deciding on concrete local energy systems. The contents in brief: -The book throws new light on the concept of energy efficiency; -A section on the environment compares how air-polluting emissions vary with different methods of energy production; -A section contains more than 40 ideas for measures which can be profitable, reduce energy consumption and the impact on the environment all at the same time; -The book gives concrete examples of new, alternative and environmentally-adapted local energy systems. More efficient use of energy is included as a possible change of energy system; -The greatest emphasis is laid upon alternative energy systems for heating. It may be heating in a house, block of flats, office building or school; -Finally, there are examples of environmentally-adapted local energy planning.

  20. Robust Multi-Frame Adaptive Optics Image Restoration Algorithm Using Maximum Likelihood Estimation with Poisson Statistics.

    Science.gov (United States)

    Li, Dongming; Sun, Changming; Yang, Jinhua; Liu, Huan; Peng, Jiaqi; Zhang, Lijuan

    2017-04-06

    An adaptive optics (AO) system provides real-time compensation for atmospheric turbulence. However, an AO image is usually of poor contrast because of the nature of the imaging process, meaning that the image contains information coming from both out-of-focus and in-focus planes of the object, which also brings about a loss in quality. In this paper, we present a robust multi-frame adaptive optics image restoration algorithm via maximum likelihood estimation. Our proposed algorithm uses a maximum likelihood method with image regularization as the basic principle, and constructs the joint log likelihood function for multi-frame AO images based on a Poisson distribution model. To begin with, a frame selection method based on image variance is applied to the observed multi-frame AO images to select images with better quality to improve the convergence of a blind deconvolution algorithm. Then, by combining the imaging conditions and the AO system properties, a point spread function estimation model is built. Finally, we develop our iterative solutions for AO image restoration addressing the joint deconvolution issue. We conduct a number of experiments to evaluate the performances of our proposed algorithm. Experimental results show that our algorithm produces accurate AO image restoration results and outperforms the current state-of-the-art blind deconvolution methods.

  1. Robust Multi-Frame Adaptive Optics Image Restoration Algorithm Using Maximum Likelihood Estimation with Poisson Statistics

    Directory of Open Access Journals (Sweden)

    Dongming Li

    2017-04-01

    Full Text Available An adaptive optics (AO system provides real-time compensation for atmospheric turbulence. However, an AO image is usually of poor contrast because of the nature of the imaging process, meaning that the image contains information coming from both out-of-focus and in-focus planes of the object, which also brings about a loss in quality. In this paper, we present a robust multi-frame adaptive optics image restoration algorithm via maximum likelihood estimation. Our proposed algorithm uses a maximum likelihood method with image regularization as the basic principle, and constructs the joint log likelihood function for multi-frame AO images based on a Poisson distribution model. To begin with, a frame selection method based on image variance is applied to the observed multi-frame AO images to select images with better quality to improve the convergence of a blind deconvolution algorithm. Then, by combining the imaging conditions and the AO system properties, a point spread function estimation model is built. Finally, we develop our iterative solutions for AO image restoration addressing the joint deconvolution issue. We conduct a number of experiments to evaluate the performances of our proposed algorithm. Experimental results show that our algorithm produces accurate AO image restoration results and outperforms the current state-of-the-art blind deconvolution methods.

  2. Micro-optical-mechanical system photoacoustic spectrometer

    Science.gov (United States)

    Kotovsky, Jack; Benett, William J.; Tooker, Angela C.; Alameda, Jennifer B.

    2013-01-01

    All-optical photoacoustic spectrometer sensing systems (PASS system) and methods include all the hardware needed to analyze the presence of a large variety of materials (solid, liquid and gas). Some of the all-optical PASS systems require only two optical-fibers to communicate with the opto-electronic power and readout systems that exist outside of the material environment. Methods for improving the signal-to-noise are provided and enable mirco-scale systems and methods for operating such systems.

  3. Modeling Adaptive Behavior for Systems Design

    DEFF Research Database (Denmark)

    Rasmussen, Jens

    1994-01-01

    Field studies in modern work systems and analysis of recent major accidents have pointed to a need for better models of the adaptive behavior of individuals and organizations operating in a dynamic and highly competitive environment. The paper presents a discussion of some key characteristics...... of the predictive models required for the design of work supports systems, that is,information systems serving as the human-work interface. Three basic issues are in focus: 1.) Some fundamental problems in analysis and modeling modern dynamic work systems caused by the adaptive nature of human behavior; 2.......) The basic difference between the models of system functions used in engineering and design and those evolving from basic research within the various academic disciplines and finally 3.) The models and methods required for closed-loop, feedback system design....

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

    DEFF Research Database (Denmark)

    Borkowski, Robert; Zhang, Xu; Zibar, Darko

    2011-01-01

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

  5. Outage Performance of Hybrid FSO/RF System with Low-Complexity Power Adaptation

    KAUST Repository

    Rakia, Tamer

    2016-02-26

    Hybrid free-space optical (FSO) / radio-frequency (RF) systems have emerged as a promising solution for high data- rate wireless communication systems. We consider truncated channel inversion based power adaptation strategy for coherent and non- coherent hybrid FSO/RF systems, employing an adaptive combining scheme. Specifically, we activate the RF link along with the FSO link when FSO link quality is unacceptable, and adaptively set RF transmission power to ensure constant combined signal-to-noise ratio at receiver terminal. Analytical expressions for the outage probability of the hybrid system with and without power adaptation are derived. Numerical examples show that, the hybrid FSO/RF systems with power adaptation achieve considerable outage performance improvement over conventional hybrid FSO/RF systems without power adaptation. © 2015 IEEE.

  6. Final Report - Regulatory Considerations for Adaptive Systems

    Science.gov (United States)

    Wilkinson, Chris; Lynch, Jonathan; Bharadwaj, Raj

    2013-01-01

    This report documents the findings of a preliminary research study into new approaches to the software design assurance of adaptive systems. We suggest a methodology to overcome the software validation and verification difficulties posed by the underlying assumption of non-adaptive software in the requirementsbased- testing verification methods in RTCA/DO-178B and C. An analysis of the relevant RTCA/DO-178B and C objectives is presented showing the reasons for the difficulties that arise in showing satisfaction of the objectives and suggested additional means by which they could be satisfied. We suggest that the software design assurance problem for adaptive systems is principally one of developing correct and complete high level requirements and system level constraints that define the necessary system functional and safety properties to assure the safe use of adaptive systems. We show how analytical techniques such as model based design, mathematical modeling and formal or formal-like methods can be used to both validate the high level functional and safety requirements, establish necessary constraints and provide the verification evidence for the satisfaction of requirements and constraints that supplements conventional testing. Finally the report identifies the follow-on research topics needed to implement this methodology.

  7. A formal protocol test procedure for the Survivable Adaptable Fiber Optic Embedded Network (SAFENET)

    Science.gov (United States)

    High, Wayne

    1993-03-01

    This thesis focuses upon a new method for verifying the correct operation of a complex, high speed fiber optic communication network. These networks are of growing importance to the military because of their increased connectivity, survivability, and reconfigurability. With the introduction and increased dependence on sophisticated software and protocols, it is essential that their operation be correct. Because of the speed and complexity of fiber optic networks being designed today, they are becoming increasingly difficult to test. Previously, testing was accomplished by application of conformance test methods which had little connection with an implementation's specification. The major goal of conformance testing is to ensure that the implementation of a profile is consistent with its specification. Formal specification is needed to ensure that the implementation performs its intended operations while exhibiting desirable behaviors. The new conformance test method presented is based upon the System of Communicating Machine model which uses a formal protocol specification to generate a test sequence. The major contribution of this thesis is the application of the System of Communicating Machine model to formal profile specifications of the Survivable Adaptable Fiber Optic Embedded Network (SAFENET) standard which results in the derivation of test sequences for a SAFENET profile. The results applying this new method to SAFENET's OSI and Lightweight profiles are presented.

  8. LSPV+7, a branch-point-tolerant reconstructor for strong turbulence adaptive optics.

    Science.gov (United States)

    Steinbock, Michael J; Hyde, Milo W; Schmidt, Jason D

    2014-06-20

    Optical wave propagation through long paths of extended turbulence presents unique challenges to adaptive optics (AO) systems. As scintillation and branch points develop in the beacon phase, challenges arise in accurately unwrapping the received wavefront and optimizing the reconstructed phase with respect to branch cut placement on a continuous facesheet deformable mirror. Several applications are currently restricted by these capability limits: laser communication, laser weapons, remote sensing, and ground-based astronomy. This paper presents a set of temporally evolving AO simulations comparing traditional least-squares reconstruction techniques to a complex-exponential reconstructor and several other reconstructors derived from the postprocessing congruence operation. The reconstructors' behavior in closed-loop operation is compared and discussed, providing several insights into the fundamental strengths and limitations of each reconstructor type. This research utilizes a self-referencing interferometer (SRI) as the high-order wavefront sensor, driving a traditional linear control law in conjunction with a cooperative point source beacon. The SRI model includes practical optical considerations and frame-by-frame fiber coupling effects to allow for realistic noise modeling. The "LSPV+7" reconstructor is shown to offer the best performance in terms of Strehl ratio and correction stability-outperforming the traditional least-squares reconstructed system by an average of 120% in the studied scenarios. Utilizing a continuous facesheet deformable mirror, these reconstructors offer significant AO performance improvements in strong turbulence applications without the need for segmented deformable mirrors.

  9. Wavelength reused bidirectional transmission of adaptively modulated optical OFDM signals in WDM-PONs incorporating SOA and RSOA intensity modulators.

    Science.gov (United States)

    Wei, J L; Hugues-Salas, E; Giddings, R P; Jin, X Q; Zheng, X; Mansoor, S; Tang, J M

    2010-05-10

    Detailed numerical investigations are undertaken of wavelength reused bidirectional transmission of adaptively modulated optical OFDM (AMOOFDM) signals over a single SMF in a colorless WDM-PON incorporating a semiconductor optical amplifier (SOA) intensity modulator and a reflective SOA (RSOA) intensity modulator in the optical line termination and optical network unit, respectively. A comprehensive theoretical model describing the performance of such network scenarios is, for the first time, developed, taking into account dynamic optical characteristics of SOA and RSOA intensity modulators as well as the effects of Rayleigh backscattering (RB) and residual downstream signal-induced crosstalk. The developed model is rigorously verified experimentally in RSOA-based real-time end-to-end OOFDM systems at 7.5 Gb/s. It is shown that the RB noise and crosstalk effects are dominant factors limiting the maximum achievable downstream and upstream transmission performance. Under optimum SOA and RSOA operating conditions as well as practical downstream and upstream optical launch powers, 10 Gb/s downstream and 6 Gb/s upstream over 40 km SMF transmissions of conventional double sideband AMOOFDM signals are feasible without utilizing in-line optical amplification and chromatic dispersion compensation. In particular, the aforementioned transmission performance can be improved to 23 Gb/s downstream and 8 Gb/s upstream over 40 km SMFs when single sideband subcarrier modulation is adopted in the downstream systems. (c) 2010 Optical Society of America.

  10. Embedded Multifunctional Optical Sensor System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — To address NASA's need for in situ sensor systems for use on rigid and/or flexible ablative Thermal Protection System (TPS) materials, Physical Optics Corporation...

  11. Fiber Optic Sensing Systems for Launch Vehicles

    Data.gov (United States)

    National Aeronautics and Space Administration — AES in partnership with HEOMD's Launch Services Program and ARMD, plans to develop Fiber Optic Sensing System (FOSS) hardware for use with Launch Vehicle Systems.AES...

  12. On complex adaptive systems and terrorism

    International Nuclear Information System (INIS)

    Ahmed, E.; Elgazzar, A.S.; Hegazi, A.S.

    2005-01-01

    Complex adaptive systems (CAS) are ubiquitous in nature. They are basic in social sciences. An overview of CAS is given with emphasize on the occurrence of bad side effects to seemingly 'wise' decisions. Hence application to terrorism is given. Some conclusions on how to deal with this phenomena are proposed

  13. Adaptive intrusion data system (AIDS) software routines

    International Nuclear Information System (INIS)

    Corlis, N.E.

    1980-07-01

    An Adaptive Intrusion Data System (AIDS) was developed to collect information from intrusion alarm sensors as part of an evaluation system to improve sensor performance. AIDS is a unique digital data-compression, storage, and formatting system; it also incorporates a capability for video selection and recording for assessment of the sensors monitored by the system. The system is software reprogrammable to numerous configurations that may be used for the collection of environmental, bilevel, analog, and video data. This report describes the software routines that control the different AIDS data-collection modes, the diagnostic programs to test the operating hardware, and the data format. Sample data printouts are also included

  14. Knowledge-based optical system design: some optical systems generated by the KBOSD

    Science.gov (United States)

    Nouri, Taoufik; Erard, Pierre-Jean

    1993-04-01

    This work is a new approach for the design of start optical systems and represents a new contribution of artificial intelligence techniques in the optical design field. A knowledge-based optical-systems design (KBOSD), based on artificial intelligence algorithms, first order logic, knowledge representation, rules, and heuristics on lens design, is realized. This KBOSD is equipped with optical knowledge in the domain of centered dioptrical optical systems used at low aperture and small field angles. This KBOSD generates centered dioptrical, on-axis and low-aperture optical-systems, which are used as start systems for the subsequent optimization by existing lens design programs. This KBOSD produces monochromatic or polychromatic optical systems, such as singlet lens, doublet lens, triplet lens, reversed singlet lens, reversed doublet lens, reversed triplet lens, and telescopes. In the design of optical systems, the KBOSD takes into account many user constraints such as cost, resistance of the optical material (glass) to chemical, thermal, and mechanical effects, as well as the optical quality such as minimal aberrations and chromatic aberrations corrections. This KBOSD is developed in the programming language Prolog and has knowledge on optical design principles and optical properties and uses neither a lens library nor a lens data base, it is completely based on optical design knowledge.

  15. Ultra-high accuracy optical testing: creating diffraction-limited short-wavelength optical systems

    International Nuclear Information System (INIS)

    Goldberg, Kenneth A.; Naulleau, Patrick P.; Rekawa, Senajith B.; Denham, Paul E.; Liddle, J. Alexander; Gullikson, Eric M.; Jackson, KeithH.; Anderson, Erik H.; Taylor, John S.; Sommargren, Gary E.; Chapman, Henry N.; Phillion, Donald W.; Johnson, Michael; Barty, Anton; Soufli, Regina; Spiller, Eberhard A.; Walton, Christopher C.; Bajt, Sasa

    2005-01-01

    Since 1993, research in the fabrication of extreme ultraviolet (EUV) optical imaging systems, conducted at Lawrence Berkeley National Laboratory (LBNL) and Lawrence Livermore National Laboratory (LLNL), has produced the highest resolution optical systems ever made. We have pioneered the development of ultra-high-accuracy optical testing and alignment methods, working at extreme ultraviolet wavelengths, and pushing wavefront-measuring interferometry into the 2-20-nm wavelength range (60-600 eV). These coherent measurement techniques, including lateral shearing interferometry and phase-shifting point-diffraction interferometry (PS/PDI) have achieved RMS wavefront measurement accuracies of 0.5-1-(angstrom) and better for primary aberration terms, enabling the creation of diffraction-limited EUV optics. The measurement accuracy is established using careful null-testing procedures, and has been verified repeatedly through high-resolution imaging. We believe these methods are broadly applicable to the advancement of short-wavelength optical systems including space telescopes, microscope objectives, projection lenses, synchrotron beamline optics, diffractive and holographic optics, and more. Measurements have been performed on a tunable undulator beamline at LBNL's Advanced Light Source (ALS), optimized for high coherent flux; although many of these techniques should be adaptable to alternative ultraviolet, EUV, and soft x-ray light sources. To date, we have measured nine prototype all-reflective EUV optical systems with NA values between 0.08 and 0.30 (f/6.25 to f/1.67). These projection-imaging lenses were created for the semiconductor industry's advanced research in EUV photolithography, a technology slated for introduction in 2009-13. This paper reviews the methods used and our program's accomplishments to date

  16. All-Optical Regeneration System for Optical Wavelength Division Multiplexed Communication Systems

    DEFF Research Database (Denmark)

    2014-01-01

    The invention relates to an all-optical regeneration system for regeneration of optical wavelength division multiplexed WDM data signals in an optical WDM communication system. The system comprises a WDM-to-Optical time domain multiplexing OTDM, WDM-to-OTDM, converter, capable of converting....... The system additionally comprises an OTDM-to-WDM converter for converting the output OTDM data signal to an output WDM data signal. An input of the all-optical regenerator unit is in optical communication with an output of the WDM-to-OTDM converter, and an output of the all-optical regenerator unit...... an input WDM data signal comprising multiple wavelength channels into an input OTDM data signal comprising multiple time multiplexed time channels. The system further comprises an all-optical regenerator unit being configured for regenerating the input OTDM data signal into an output OTDM data signal...

  17. Changing Paradigms: From Schooling to Schools as Adaptive Recommendation Systems

    DEFF Research Database (Denmark)

    Christiansen, René Boyer; Gynther, Karsten; Petersen, Anne Kristine

    2017-01-01

    The paper explores a shift in education from educational systems requiring student adaptation to educational recommendation systems adapting to students’ individual needs. The paper discusses the concept of adaptation as addressed in educational research and draws on the system theory of Heinz von...... system adaptation and recommendation systems. These different understandings constitute a design framework that is used to analyze two current trends: Adaptive learning systems and learning analytics. Finally, the paper discusses the potential of looking at adaptation as recommendation systems...... Foerster to shed light on how the educational system has used and understood adaptation. In this context, we point out two different approaches to educational adaptation: 1) students adapting to the educational system and 2) the attempt of the educational system to adapt to students through automatized...

  18. Integrated Optical Interconnect Architectures for Embedded Systems

    CERN Document Server

    Nicolescu, Gabriela

    2013-01-01

    This book provides a broad overview of current research in optical interconnect technologies and architectures. Introductory chapters on high-performance computing and the associated issues in conventional interconnect architectures, and on the fundamental building blocks for integrated optical interconnect, provide the foundations for the bulk of the book which brings together leading experts in the field of optical interconnect architectures for data communication. Particular emphasis is given to the ways in which the photonic components are assembled into architectures to address the needs of data-intensive on-chip communication, and to the performance evaluation of such architectures for specific applications.   Provides state-of-the-art research on the use of optical interconnects in Embedded Systems; Begins with coverage of the basics for high-performance computing and optical interconnect; Includes a variety of on-chip optical communication topologies; Features coverage of system integration and opti...

  19. Two Perspectives on Information System Adaptation

    DEFF Research Database (Denmark)

    Jensen, Tina Blegind; Kjærgaard, Annemette; Svejvig, Per

    Institutional theory has proven to be a central analytical perspective for investigating the role of larger social and historical structures of Information System (IS) adaptation. However, it does not explicitly account for how organizational actors make sense of and enact IS in their local context...... for investigating the phenomenon of IS adaptation. Furthermore, we explore a combination of the two theories with a case study in a health care setting where an Electronic Patient Record (EPR) system was introduced and used by a group of doctors. The empirical case provides evidence of how existing institutional...... structures influenced the doctors' sensemaking of the EPR system. Additionally, it illustrates how the doctors made sense of the EPR system in practice. The paper outlines that: 1) institutional theory has its explanatory power at the organizational field and organizational/group level of analysis focusing...

  20. Drawing inspiration from biological optical systems

    Science.gov (United States)

    Wolpert, H. D.

    2009-08-01

    Bio-Mimicking/Bio-Inspiration: How can we not be inspired by Nature? Life has evolved on earth over the last 3.5 to 4 billion years. Materials formed during this time were not toxic; they were created at low temperatures and low pressures unlike many of the materials developed today. The natural materials formed are self-assembled, multifunctional, nonlinear, complex, adaptive, self-repairing and biodegradable. The designs that failed are fossils. Those that survived are the success stories. Natural materials are mostly formed from organics, inorganic crystals and amorphous phases. The materials make economic sense by optimizing the design of the structures or systems to meet multiple needs. We constantly "see" many similar strategies in approaches, between man and nature, but we seldom look at the details of natures approaches. The power of image processing, in many of natures creatures, is a detail that is often overlooked. Seldon does the engineer interact with the biologist and learn what nature has to teach us. The variety and complexity of biological materials and the optical systems formed should inspire us.

  1. Model reference adaptive systems some examples.

    Science.gov (United States)

    Landau, I. D.; Sinner, E.; Courtiol, B.

    1972-01-01

    A direct design method is derived for several single-input single-output model reference adaptive systems (M.R.A.S.). The approach used helps to clarify the various steps involved in a design, which utilizes the hyperstability concept. An example of a multiinput, multioutput M.R.A.S. is also discussed. Attention is given to the problem of a series compensator. It is pointed out that a series compensator which contains derivative terms must generally be introduced in the adaptation mechanism in order to assure asymptotic hyperstability. Results obtained by the simulation of a M.R.A.S. on an analog computer are also presented.

  2. Processing and Linguistics Properties of Adaptable Systems

    Directory of Open Access Journals (Sweden)

    Dumitru TODOROI

    2006-01-01

    Full Text Available Continuation and development of the research in Adaptable Programming Initialization [Tod-05.1,2,3] is presented. As continuation of [Tod-05.2,3] in this paper metalinguistic tools used in the process of introduction of new constructions (data, operations, instructions and controls are developed. The generalization schemes of evaluation of adaptable languages and systems are discussed. These results analogically with [Tod-05.2,3] are obtained by the team, composed from the researchers D. Todoroi [Tod-05.4], Z. Todoroi [ZTod-05], and D. Micusa [Mic-03]. Presented results will be included in the book [Tod-06].

  3. Non-Hermitian optics in atomic systems

    Science.gov (United States)

    Zhang, Zhaoyang; Ma, Danmeng; Sheng, Jiteng; Zhang, Yiqi; Zhang, Yanpeng; Xiao, Min

    2018-04-01

    A wide class of non-Hermitian Hamiltonians can possess entirely real eigenvalues when they have parity-time (PT) symmetric potentials. Recently, this family of non-Hermitian systems has attracted considerable attention in diverse areas of physics due to their extraordinary properties, especially in optical systems based on solid-state materials, such as coupled gain-loss waveguides and microcavities. Considering the desired refractive index can be effectively manipulated through atomic coherence, it is important to realize such non-Hermitian optical potentials and further investigate their distinct properties in atomic systems. In this paper, we review the recent theoretical and experimental progress of non-Hermitian optics with coherently prepared multi-level atomic configurations. The realizations of (anti-) PT symmetry with different schemes have extensively demonstrated the special optical properties of non-Hermitian optical systems with atomic coherence.

  4. Rate adaptive multilevel coded modulation with high coding gain in intensity modulation direct detection optical communication

    Science.gov (United States)

    Xiao, Fei; Liu, Bo; Zhang, Lijia; Xin, Xiangjun; Zhang, Qi; Tian, Qinghua; Tian, Feng; Wang, Yongjun; Rao, Lan; Ullah, Rahat; Zhao, Feng; Li, Deng'ao

    2018-02-01

    A rate-adaptive multilevel coded modulation (RA-MLC) scheme based on fixed code length and a corresponding decoding scheme is proposed. RA-MLC scheme combines the multilevel coded and modulation technology with the binary linear block code at the transmitter. Bits division, coding, optional interleaving, and modulation are carried out by the preset rule, then transmitted through standard single mode fiber span equal to 100 km. The receiver improves the accuracy of decoding by means of soft information passing through different layers, which enhances the performance. Simulations are carried out in an intensity modulation-direct detection optical communication system using MATLAB®. Results show that the RA-MLC scheme can achieve bit error rate of 1E-5 when optical signal-to-noise ratio is 20.7 dB. It also reduced the number of decoders by 72% and realized 22 rate adaptation without significantly increasing the computing time. The coding gain is increased by 7.3 dB at BER=1E-3.

  5. MAD ADAPTIVE OPTICS IMAGING OF HIGH-LUMINOSITY QUASARS: A PILOT PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Liuzzo, E. [Osservatorio di Radioastronomia, INAF, via Gobetti 101, I-40129 Bologna (Italy); Falomo, R.; Paiano, S.; Baruffolo, A.; Farinato, J.; Moretti, A.; Ragazzoni, R. [Osservatorio Astronomico di Padova, INAF, vicolo dell’Osservatorio 5, I-35122 Padova (Italy); Treves, A. [Università dell’Insubria (Como) (Italy); Uslenghi, M. [INAF-IASF, via E. Bassini 15, I-20133 Milano (Italy); Arcidiacono, C.; Diolaiti, E.; Lombini, M. [Osservatorio Astronomico di Bologna, INAF, Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Brast, R. [Dipartimento di Fisica e Astronomia, Università di Bologna, Via Irnerio, 46, I-40126, Bologna (Italy); Donaldson, R.; Kolb, J.; Marchetti, E.; Tordo, S., E-mail: liuzzo@ira.inaf.it [European Southern Observatory, Karl-Schwarschild-Strasse 2, D-85748 Garching bei München (Germany)

    2016-08-01

    We present near-IR images of five luminous quasars at z ∼ 2 and one at z ∼ 4 obtained with an experimental adaptive optics (AO) instrument at the European Southern Observatory Very Large Telescope. The observations are part of a program aimed at demonstrating the capabilities of multi-conjugated adaptive optics imaging combined with the use of natural guide stars for high spatial resolution studies on large telescopes. The observations were mostly obtained under poor seeing conditions but in two cases. In spite of these nonoptimal conditions, the resulting images of point sources have cores of FWHM ∼ 0.2 arcsec. We are able to characterize the host galaxy properties for two sources and set stringent upper limits to the galaxy luminosity for the others. We also report on the expected capabilities for investigating the host galaxies of distant quasars with AO systems coupled with future Extremely Large Telescopes. Detailed simulations show that it will be possible to characterize compact (2–3 kpc) quasar host galaxies for quasi-stellar objects at z = 2 with nucleus K -magnitude spanning from 15 to 20 (corresponding to absolute magnitude −31 to −26) and host galaxies that are 4 mag fainter than their nuclei.

  6. Research on adaptive optics image restoration algorithm based on improved joint maximum a posteriori method

    Science.gov (United States)

    Zhang, Lijuan; Li, Yang; Wang, Junnan; Liu, Ying

    2018-03-01

    In this paper, we propose a point spread function (PSF) reconstruction method and joint maximum a posteriori (JMAP) estimation method for the adaptive optics image restoration. Using the JMAP method as the basic principle, we establish the joint log likelihood function of multi-frame adaptive optics (AO) images based on the image Gaussian noise models. To begin with, combining the observed conditions and AO system characteristics, a predicted PSF model for the wavefront phase effect is developed; then, we build up iterative solution formulas of the AO image based on our proposed algorithm, addressing the implementation process of multi-frame AO images joint deconvolution method. We conduct a series of experiments on simulated and real degraded AO images to evaluate our proposed algorithm. Compared with the Wiener iterative blind deconvolution (Wiener-IBD) algorithm and Richardson-Lucy IBD algorithm, our algorithm has better restoration effects including higher peak signal-to-noise ratio ( PSNR) and Laplacian sum ( LS) value than the others. The research results have a certain application values for actual AO image restoration.

  7. Adaptable Transponder for Multiple Telemetry Systems

    Science.gov (United States)

    Sims, William Herbert, III (Inventor); Varnavas, Kosta A. (Inventor)

    2014-01-01

    The present invention is a stackable telemetry circuit board for use in telemetry systems for satellites and other purposes. The present invention incorporates previously-qualified interchangeable circuit boards, or "decks," that perform functions such as power, signal receiving and transmission, and processing. Each deck is adapted to serve a range of telemetry applications. This provides flexibility in the construction of the stackable telemetry circuit board and significantly reduces the cost and time necessary to develop a telemetry system.

  8. Adaptive Optics for Direct Detection of Extrasolar Planets: The Gemini Planet Imager

    Energy Technology Data Exchange (ETDEWEB)

    Macintosh, B; Graham, J; Palmer, D; Doyon, R; Gavel, D; Larkin, J; Oppenheimer, B; Saddlemyer, L; Wallace, J K; Bauman, B; Erikson, D; Poyneer, L; Sivaramakrishnan, A; Soummer, R; Veran, J

    2007-04-24

    The direct detection of photons emitted or reflected by extrasolar planets, spatially resolved from their parent star, is a major frontier in the study of other solar systems. Direct detection will provide statistical information on planets in 5-50 AU orbits, inaccessible to current Doppler searches, and allow spectral characterization of radius, temperature, surface gravity, and perhaps composition. Achieving this will require new dedicated high-contrast instruments. One such system under construction is the Gemini Planet Imager (GPI.) This combines a high-order/high-speed adaptive optics system to control wavefront errors from the Earth's atmosphere, an advanced coronagraph to block diffraction, ultrasmooth optics, a precision infrared interferometer to measure and correct systematic errors, and a integral field spectrograph/polarimeter to image and characterize target planetary systems. We predict that GPI will be able to detect planets with brightness less than 10{sup -7} of their parent star, sufficient to observe warm self-luminous planets around a large population of targets.

  9. Adaptive optics for deeper imaging of biological samples.

    Science.gov (United States)

    Girkin, John M; Poland, Simon; Wright, Amanda J

    2009-02-01

    Optical microscopy has been a cornerstone of life science investigations since its first practical application around 400 years ago with the goal being subcellular resolution, three-dimensional images, at depth, in living samples. Nonlinear microscopy brought this dream a step closer, but as one images more deeply the material through which you image can greatly distort the view. By using optical devices, originally developed for astronomy, whose optical properties can be changed in real time, active compensation for sample-induced aberrations is possible. Submicron resolution images are now routinely recorded from depths over 1mm into tissue. Such active optical elements can also be used to keep conventional microscopes, both confocal and widefield, in optimal alignment.

  10. Beam optics: computer program for electrostatic optical systems

    International Nuclear Information System (INIS)

    Roussel, Joseph.

    1976-06-01

    A computer program has been written to calculate the parameters of electrostatic optical systems with a cylindrical geometry required for atomic physics experiments. Very easy to use, this program allows the calculation of the electric potential chart to be performed by an iterative method (Frankel and Young method). The equipotentials and trajectories can be plotted, to make easier the interpretation of the results [fr

  11. Optical system for trapping particles in air.

    Science.gov (United States)

    Kampmann, R; Chall, A K; Kleindienst, R; Sinzinger, S

    2014-02-01

    An innovative optical system for trapping particles in air is presented. We demonstrate an optical system specifically optimized for high precision positioning of objects with a size of several micrometers within a nanopositioning and nanomeasuring machine (NPMM). Based on a specification sheet, an initial system design was calculated and optimized in an iterative design process. By combining optical design software with optical force simulation tools, a highly efficient optical system was developed. Both components of the system, which include a refractive double axicon and a parabolic ring mirror, were fabricated by ultra-precision turning. The characterization of the optical elements and the whole system, especially the force simulations based on caustic measurements, represent an important interim result for the subsequently performed trapping experiments. The caustic of the trapping beam produced by the system was visualized with the help of image processing techniques. Finally, we demonstrated the unique efficiency of the configuration by reproducibly trapping fused silica spheres with a diameter of 10 μm at a distance of 2.05 mm from the final optical surface.

  12. Adaptive traffic control systems for urban networks

    Directory of Open Access Journals (Sweden)

    Radivojević Danilo

    2017-01-01

    Full Text Available Adaptive traffic control systems represent complex, but powerful tool for improvement of traffic flow conditions in locations or zones where applied. Many traffic agencies, especially those that have a large number of signalized intersections with high variability of the traffic demand, choose to apply some of the adaptive traffic control systems. However, those systems are manufactured and offered by multiple vendors (companies that are competing for the market share. Due to that fact, besides the information available from the vendors themselves, or the information from different studies conducted on different continents, very limited amount of information is available about the details how those systems are operating. The reason for that is the protecting of the intellectual property from plagiarism. The primary goal of this paper is to make a brief analysis of the functionalities, characteristics, abilities and results of the most recognized, but also less known adaptive traffic control systems to the professional public and other persons with interest in this subject.

  13. A neural systems analysis of adaptive navigation.

    Science.gov (United States)

    Mizumori, S J; Cooper, B G; Leutgeb, S; Pratt, W E

    2000-01-01

    In the field of the neurobiology of learning, significant emphasis has been placed on understanding neural plasticity within a single structure (or synapse type) as it relates to a particular type of learning mediated by a particular brain area. To appreciate fully the breadth of the plasticity responsible for complex learning phenomena, it is imperative that we also examine the neural mechanisms of the behavioral instantiation of learned information, how motivational systems interact, and how past memories affect the learning process. To address this issue, we describe a model of complex learning (rodent adaptive navigation) that could be used to study dynamically interactive neural systems. Adaptive navigation depends on the efficient integration of external and internal sensory information with motivational systems to arrive at the most effective cognitive and/or behavioral strategies. We present evidence consistent with the view that during navigation: 1) the limbic thalamus and limbic cortex is primarily responsible for the integration of current and expected sensory information, 2) the hippocampal-septal-hypothalamic system provides a mechanism whereby motivational perspectives bias sensory processing, and 3) the amygdala-prefrontal-striatal circuit allows animals to evaluate the expected reinforcement consequences of context-dependent behavioral responses. Although much remains to be determined regarding the nature of the interactions among neural systems, new insights have emerged regarding the mechanisms that underlie flexible and adaptive behavioral responses.

  14. A system for obtaining an optical spectrum

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention relates to a system for obtaining an optical spectrum 648 of analytes in a fluid sample, wherein a porous filter 602a, 602b is arranged so that the fluid sample may be placed onto a first region of the porous filter, and a SERS-active material 610a, 610b having a SERS...... the second region. Thereby, the porous filter enables that the fluid sample is filtered so that only sufficiently small entities in the fluid sample reach the second region where they may be probed so that an optical spectrum related to the analytes in the filtered sample may be obtained. The optical system...... also comprises a light source 634, a light detector 642, and the optical analysis system is arranged for obtaining the optical spectrum 648 of the analytes adjacent to the SERS-active material 610a, 610b exclusively from the second region of the porous filter 602a, 602b....

  15. Optical solar energy adaptations and radiative temperature control of green leaves and tree barks

    Energy Technology Data Exchange (ETDEWEB)

    Henrion, Wolfgang; Tributsch, Helmut [Department of Si-Photovoltaik and Solare Energetik, Hahn-Meitner-Institut Berlin, 14109 Berlin (Germany)

    2009-01-15

    Trees have adapted to keep leaves and barks cool in sunshine and can serve as interesting bionic model systems for radiative cooling. Silicon solar cells, on the other hand, loose up to one third of their energy efficiency due to heating in intensive sunshine. It is shown that green leaves minimize absorption of useful radiation and allow efficient infrared thermal emission. Since elevated temperatures are detrimental for tensile water flow in the Xylem tissue below barks, the optical properties of barks should also have evolved so as to avoid excessive heating. This was tested by performing optical studies with tree bark samples from representative trees. It was found that tree barks have optimized their reflection of incoming sunlight between 0.7 and 2 {mu}m. This is approximately the optical window in which solar light is transmitted and reflected by green vegetation. Simultaneously, the tree bark is highly absorbing and thus radiation emitting between 6 and 10 {mu}m. These two properties, mainly provided by tannins, create optimal conditions for radiative temperature control. In addition, tannins seem to have adopted a function as mediators for excitation energy towards photo-antioxidative activity for control of radiation damage. The results obtained are used to discuss challenges for future solar cell optimization. (author)

  16. Fiber optical parametric amplifiers in optical communication systems

    DEFF Research Database (Denmark)

    Marhic, Michel E.; Andrekson, Peter A.; Petropoulos, Periklis

    2015-01-01

    The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time...... in excess of 14,000 Tb/s x km in realistic wavelength-division multiplexed long-haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long-haul communication networks are discussed....

  17. Adaptive Embedded Digital System for Plasma Diagnostics

    Science.gov (United States)

    González, Angel; Rodríguez, Othoniel; Mangual, Osvaldo; Ponce, Eduardo; Vélez, Xavier

    2014-05-01

    An Adaptive Embedded Digital System to perform plasma diagnostics using electrostatic probes was developed at the Plasma Engineering Laboratory at Polytechnic University of Puerto Rico. The system will replace the existing instrumentation at the Laboratory, using reconfigurable hardware to minimize the equipment and software needed to perform diagnostics. The adaptability of the design resides on the possibility of replacing the computational algorithm on the fly, allowing to use the same hardware for different probes. The system was prototyped using Very High Speed Integrated Circuits Hardware Description Language (VHDL) into an Field Programmable Gate Array (FPGA) board. The design of the Embedded Digital System includes a Zero Phase Digital Filter, a Derivative Unit, and a Computational Unit designed using the VHDL-2008 Support Library. The prototype is able to compute the Plasma Electron Temperature and Density from a Single Langmuir probe. The system was tested using real data previously acquired from a single Langmuir probe. The plasma parameters obtained from the embedded system were compared with results computed using matlab yielding excellent matching. The new embedded system operates on 4096 samples versus 500 on the previous system, and completes its computations in 26 milliseconds compared with about 15 seconds on the previous system.

  18. Intelligent Adaptation Process for Case Based Systems

    International Nuclear Information System (INIS)

    Nassar, A.M.; Mohamed, A.H.; Mohamed, A.H.

    2014-01-01

    Case Based Reasoning (CBR) Systems is one of the important decision making systems applied in many fields all over the world. The effectiveness of any CBR system based on the quality of the storage cases in the case library. Similar cases can be retrieved and adapted to produce the solution for the new problem. One of the main issues faced the CBR systems is the difficulties of achieving the useful cases. The proposed system introduces a new approach that uses the genetic algorithm (GA) technique to automate constructing the cases into the case library. Also, it can optimize the best one to be stored in the library for the future uses. However, the proposed system can avoid the problems of the uncertain and noisy cases. Besides, it can simply the retrieving and adaptation processes. So, it can improve the performance of the CBR system. The suggested system can be applied for many real-time problems. It has been applied for diagnosis the faults of the wireless network, diagnosis of the cancer diseases, diagnosis of the debugging of a software as cases of study. The proposed system has proved its performance in this field

  19. Lowered threshold energy for femtosecond laser induced optical breakdown in a water based eye model by aberration correction with adaptive optics.

    Science.gov (United States)

    Hansen, Anja; Géneaux, Romain; Günther, Axel; Krüger, Alexander; Ripken, Tammo

    2013-06-01

    In femtosecond laser ophthalmic surgery tissue dissection is achieved by photodisruption based on laser induced optical breakdown. In order to minimize collateral damage to the eye laser surgery systems should be optimized towards the lowest possible energy threshold for photodisruption. However, optical aberrations of the eye and the laser system distort the irradiance distribution from an ideal profile which causes a rise in breakdown threshold energy even if great care is taken to minimize the aberrations of the system during design and alignment. In this study we used a water chamber with an achromatic focusing lens and a scattering sample as eye model and determined breakdown threshold in single pulse plasma transmission loss measurements. Due to aberrations, the precise lower limit for breakdown threshold irradiance in water is still unknown. Here we show that the threshold energy can be substantially reduced when using adaptive optics to improve the irradiance distribution by spatial beam shaping. We found that for initial aberrations with a root-mean-square wave front error of only one third of the wavelength the threshold energy can still be reduced by a factor of three if the aberrations are corrected to the diffraction limit by adaptive optics. The transmitted pulse energy is reduced by 17% at twice the threshold. Furthermore, the gas bubble motions after breakdown for pulse trains at 5 kilohertz repetition rate show a more transverse direction in the corrected case compared to the more spherical distribution without correction. Our results demonstrate how both applied and transmitted pulse energy could be reduced during ophthalmic surgery when correcting for aberrations. As a consequence, the risk of retinal damage by transmitted energy and the extent of collateral damage to the focal volume could be minimized accordingly when using adaptive optics in fs-laser surgery.

  20. Mobile based optical form evaluation system

    Directory of Open Access Journals (Sweden)

    Asım Sinan YÜKSEL

    2016-05-01

    Full Text Available Optical forms that contain multiple-choice answers are widely used both for electing students and evaluating student achievements in education systems in our country and worldwide. Optical forms are evaluated by employing optical mark recognition techniques through optical readers. High cost of these machines, limited access to them, long waiting time for evaluation results make the process hard for educationists working in cities or countries. In this study, a mobile application was developed for the educationists who own mobile phones or tablets for the purpose of evaluating students' answer sheets quickly and independent of location and optical readers. Optical form recognition, reading and evaluation processes are done on the image of student's answer sheet that is taken with the mobile phone or tablet of educationist. The Android based mobile application that we developed has a user-friendly interface, high success rate and is the first of our knowledge application that operates on mobile platforms in this field.

  1. Adaptive optics fundus images of cone photoreceptors in the macula of patients with retinitis pigmentosa.

    Science.gov (United States)

    Tojo, Naoki; Nakamura, Tomoko; Fuchizawa, Chiharu; Oiwake, Toshihiko; Hayashi, Atsushi

    2013-01-01

    The purpose of this study was to examine cone photoreceptors in the macula of patients with retinitis pigmentosa using an adaptive optics fundus camera and to investigate any correlations between cone photoreceptor density and findings on optical coherence tomography and fundus autofluorescence. We examined two patients with typical retinitis pigmentosa who underwent ophthalmological examination, including measurement of visual acuity, and gathering of electroretinographic, optical coherence tomographic, fundus autofluorescent, and adaptive optics fundus images. The cone photoreceptors in the adaptive optics images of the two patients with retinitis pigmentosa and five healthy subjects were analyzed. An abnormal parafoveal ring of high-density fundus autofluorescence was observed in the macula in both patients. The border of the ring corresponded to the border of the external limiting membrane and the inner segment and outer segment line in the optical coherence tomographic images. Cone photoreceptors at the abnormal parafoveal ring were blurred and decreased in the adaptive optics images. The blurred area corresponded to the abnormal parafoveal ring in the fundus autofluorescence images. Cone densities were low at the blurred areas and at the nasal and temporal retina along a line from the fovea compared with those of healthy controls. The results for cone spacing and Voronoi domains in the macula corresponded with those for the cone densities. Cone densities were heavily decreased in the macula, especially at the parafoveal ring on high-density fundus autofluorescence in both patients with retinitis pigmentosa. Adaptive optics images enabled us to observe in vivo changes in the cone photoreceptors of patients with retinitis pigmentosa, which corresponded to changes in the optical coherence tomographic and fundus autofluorescence images.

  2. Understanding Supply Networks from Complex Adaptive Systems

    Directory of Open Access Journals (Sweden)

    Jamur Johnas Marchi

    2014-10-01

    Full Text Available This theoretical paper is based on complex adaptive systems (CAS that integrate dynamic and holistic elements, aiming to discuss supply networks as complex systems and their dynamic and co-evolutionary processes. The CAS approach can give clues to understand the dynamic nature and co-evolution of supply networks because it consists of an approach that incorporates systems and complexity. This paper’s overall contribution is to reinforce the theoretical discussion of studies that have addressed supply chain issues, such as CAS.

  3. Semantic models for adaptive interactive systems

    CERN Document Server

    Hussein, Tim; Lukosch, Stephan; Ziegler, Jürgen; Calvary, Gaëlle

    2013-01-01

    Providing insights into methodologies for designing adaptive systems based on semantic data, and introducing semantic models that can be used for building interactive systems, this book showcases many of the applications made possible by the use of semantic models.Ontologies may enhance the functional coverage of an interactive system as well as its visualization and interaction capabilities in various ways. Semantic models can also contribute to bridging gaps; for example, between user models, context-aware interfaces, and model-driven UI generation. There is considerable potential for using

  4. Digital optical correlator x-ray telescope alignment monitoring system

    Science.gov (United States)

    Lis, Tomasz; Gaskin, Jessica; Jasper, John; Gregory, Don A.

    2018-01-01

    The High-Energy Replicated Optics to Explore the Sun (HEROES) program is a balloon-borne x-ray telescope mission to observe hard x-rays (˜20 to 70 keV) from the sun and multiple astrophysical targets. The payload consists of eight mirror modules with a total of 114 optics that are mounted on a 6-m-long optical bench. Each mirror module is complemented by a high-pressure xenon gas scintillation proportional counter. Attached to the payload is a camera that acquires star fields and then matches the acquired field to star maps to determine the pointing of the optical bench. Slight misalignments between the star camera, the optical bench, and the telescope elements attached to the optical bench may occur during flight due to mechanical shifts, thermal gradients, and gravitational effects. These misalignments can result in diminished imaging and reduced photon collection efficiency. To monitor these misalignments during flight, a supplementary Bench Alignment Monitoring System (BAMS) was added to the payload. BAMS hardware comprises two cameras mounted directly to the optical bench and rings of light-emitting diodes (LEDs) mounted onto the telescope components. The LEDs in these rings are mounted in a predefined, asymmetric pattern, and their positions are tracked using an optical/digital correlator. The BAMS analysis software is a digital adaption of an optical joint transform correlator. The aim is to enhance the observational proficiency of HEROES while providing insight into the magnitude of mechanically and thermally induced misalignments during flight. Results from a preflight test of the system are reported.

  5. Next generation intelligent environments ambient adaptive systems

    CERN Document Server

    Nothdurft, Florian; Heinroth, Tobias; Minker, Wolfgang

    2016-01-01

    This book covers key topics in the field of intelligent ambient adaptive systems. It focuses on the results worked out within the framework of the ATRACO (Adaptive and TRusted Ambient eCOlogies) project. The theoretical background, the developed prototypes, and the evaluated results form a fertile ground useful for the broad intelligent environments scientific community as well as for industrial interest groups. The new edition provides: Chapter authors comment on their work on ATRACO with final remarks as viewed in retrospective Each chapter has been updated with follow-up work emerging from ATRACO An extensive introduction to state-of-the-art statistical dialog management for intelligent environments Approaches are introduced on how Trust is reflected during the dialog with the system.

  6. Environment Adaptive Lighting Systems for Smart Homes

    Directory of Open Access Journals (Sweden)

    Cem Mehmet Catalbas

    2017-09-01

    Full Text Available In this work, an application of adaptive lighting system is proposed for smart homes. In this paper, it is suggested that, an intelligent lighting system with outdoor adaptation can be realized via a real fisheye image. During the implementation of the proposed method, the fuzzy c-means method, which is a commonly used data clustering method, has been used. The input image is divided into three different regions according to its brightness levels. Then, the RGB image is converted to CIE 1931 XYZ color space; and the obtained XYZ values are converted to x and y values. The parameters of x and y values are shown in CIE Chromaticity Diagram for different regions in the sky. Thereafter, the coordinate values are converted to Correlated Color Temperature by using two different formulas. Additionally, the conversion results are examined with respect to actual and estimated CCT values.

  7. Information Engineering and Adaptive Data Systems

    Science.gov (United States)

    King, T. A.; Walker, R. J.; Joy, S. P.; Roberts, D. A.; Thieman, J. R.

    2006-12-01

    Information engineering is a rigorous architectural approach to developing and deploying applications within an enterprise. It progresses through natural stages of analysis, design and implementation with the focus on how information is organized to achieve desired objectives. NASA has undertaken the task of organizing and leveraging the vast expanse of information in the Heliophysics domain. To achieve this goal NASA has supported the SPASE modeling effort and established domain specific Virtual Observatories. We explore how this effort fits into an information engineering approach and discuss the important and relevance of data modeling, standardization and open frameworks to achieving NASA's goals. The SPASE modeling effort and independent analysis by some of the Virtual Observatories have determined that the best solution is the development of data systems that are organized based on available resources, that is, adaptive to their environment. We explore why adaptive data systems are the best choice for reducing information entropy, adding value and improving information dissemination within NASA's Heliophysics domain.

  8. System for optical sorting of microscopic objects

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a system for optical sorting of microscopic objects and corresponding method. An optical detection system (52) is capable of determining the positions of said first and/or said second objects. One or more force transfer units (200, 205, 210, 215) are placed...... in a first reservoir, the one or more force units being suitable for optical momentum transfer. An electromagnetic radiation source (42) yields a radiation beam (31, 32) capable of optically displacing the force transfer units from one position to another within the first reservoir (1R). The force transfer...... units are displaced from positions away from the first objects to positions close to the first objects, and then displacing the first objects via a contact force (300) between the first objects and the force transfer units facilitates an optical sorting of the first objects and the second objects....

  9. Optical Digital Image Storage System

    Science.gov (United States)

    1991-03-18

    who directly contributed to ODISS. David R. Allder Irene C. Anthony Anna M. Barnaba Juanita M. Bennett Carolyn L. Bernaski Kevin L. Bradley -Jean Bray...optical disk can be described as the laser beam heating a pre-magnetized spot on the disk. Wheu the spot is heated to the curie point, a small external

  10. Adaptive stimulus optimization for sensory systems neuroscience

    OpenAIRE

    DiMattina, Christopher; Zhang, Kechen

    2013-01-01

    In this paper, we review several lines of recent work aimed at developing practical methods for adaptive on-line stimulus generation for sensory neurophysiology. We consider various experimental paradigms where on-line stimulus optimization is utilized, including the classical optimal stimulus paradigm where the goal of experiments is to identify a stimulus which maximizes neural responses, the iso-response paradigm which finds sets of stimuli giving rise to constant responses, and the system...

  11. Fiber Optic Communication System For Medical Images

    Science.gov (United States)

    Arenson, Ronald L.; Morton, Dan E.; London, Jack W.

    1982-01-01

    This paper discusses a fiber optic communication system linking ultrasound devices, Computerized tomography scanners, Nuclear Medicine computer system, and a digital fluoro-graphic system to a central radiology research computer. These centrally archived images are available for near instantaneous recall at various display consoles. When a suitable laser optical disk is available for mass storage, more extensive image archiving will be added to the network including digitized images of standard radiographs for comparison purposes and for remote display in such areas as the intensive care units, the operating room, and selected outpatient departments. This fiber optic system allows for a transfer of high resolution images in less than a second over distances exceeding 2,000 feet. The advantages of using fiber optic cables instead of typical parallel or serial communication techniques will be described. The switching methodology and communication protocols will also be discussed.

  12. Complex Adaptive Systems of Systems (CASOS) engineering environment.

    Energy Technology Data Exchange (ETDEWEB)

    Detry, Richard Joseph; Linebarger, John Michael; Finley, Patrick D.; Maffitt, S. Louise; Glass, Robert John, Jr.; Beyeler, Walter Eugene; Ames, Arlo Leroy

    2012-02-01

    Complex Adaptive Systems of Systems, or CASoS, are vastly complex physical-socio-technical systems which we must understand to design a secure future for the nation. The Phoenix initiative implements CASoS Engineering principles combining the bottom up Complex Systems and Complex Adaptive Systems view with the top down Systems Engineering and System-of-Systems view. CASoS Engineering theory and practice must be conducted together to develop a discipline that is grounded in reality, extends our understanding of how CASoS behave and allows us to better control the outcomes. The pull of applications (real world problems) is critical to this effort, as is the articulation of a CASoS Engineering Framework that grounds an engineering approach in the theory of complex adaptive systems of systems. Successful application of the CASoS Engineering Framework requires modeling, simulation and analysis (MS and A) capabilities and the cultivation of a CASoS Engineering Community of Practice through knowledge sharing and facilitation. The CASoS Engineering Environment, itself a complex adaptive system of systems, constitutes the two platforms that provide these capabilities.

  13. Optics and multilayer coatings for EUVL systems

    Energy Technology Data Exchange (ETDEWEB)

    Soufli, R; Bajt, S; Hudyma, R M; Taylor, J S

    2008-03-21

    EUV lithography (EUVL) employs illumination wavelengths around 13.5 nm, and in many aspects it is considered an extension of optical lithography, which is used for the high-volume manufacturing (HVM) of today's microprocessors. The EUV wavelength of illumination dictates the use of reflective optical elements (mirrors) as opposed to the refractive lenses used in conventional lithographic systems. Thus, EUVL tools are based on all-reflective concepts: they use multilayer (ML) coated optics for their illumination and projection systems, and they have a ML-coated reflective mask.

  14. Fiber optic neutron imaging system: calibration

    International Nuclear Information System (INIS)

    Malone, R.M.; Gow, C.E.; Thayer, D.R.

    1981-01-01

    Two neutron imaging experiments using fiber optics have been performed at the Nevada Test Site. In each experiment, an array of scintillator fluor tubes is exposed to neutrons. Light is coupled out through radiation resistant PCS fibers (8-m long) into high-bandwidth, graded index fibers. For image reconstruction to be accurate, common timing differences and transmission variations between fiber optic channels are needed. The calibration system featured a scanning pulsed dye laser, a specially designed fiber optic star coupler, a tektronix 7912AD transient digitizer, and a DEC PDP 11/34 computing system

  15. Gaia as a complex adaptive system.

    Science.gov (United States)

    Lenton, Timothy M; van Oijen, Marcel

    2002-05-29

    We define the Gaia system of life and its environment on Earth, review the status of the Gaia theory, introduce potentially relevant concepts from complexity theory, then try to apply them to Gaia. We consider whether Gaia is a complex adaptive system (CAS) in terms of its behaviour and suggest that the system is self-organizing but does not reside in a critical state. Gaia has supported abundant life for most of the last 3.8 Gyr. Large perturbations have occasionally suppressed life but the system has always recovered without losing the capacity for large-scale free energy capture and recycling of essential elements. To illustrate how complexity theory can help us understand the emergence of planetary-scale order, we present a simple cellular automata (CA) model of the imaginary planet Daisyworld. This exhibits emergent self-regulation as a consequence of feedback coupling between life and its environment. Local spatial interaction, which was absent from the original model, can destabilize the system by generating bifurcation regimes. Variation and natural selection tend to remove this instability. With mutation in the model system, it exhibits self-organizing adaptive behaviour in its response to forcing. We close by suggesting how artificial life ('Alife') techniques may enable more comprehensive feasibility tests of Gaia.

  16. An automated algorithm for photoreceptors counting in adaptive optics retinal images

    Science.gov (United States)

    Liu, Xu; Zhang, Yudong; Yun, Dai

    2012-10-01

    Eyes are important organs of humans that detect light and form spatial and color vision. Knowing the exact number of cones in retinal image has great importance in helping us understand the mechanism of eyes' function and the pathology of some eye disease. In order to analyze data in real time and process large-scale data, an automated algorithm is designed to label cone photoreceptors in adaptive optics (AO) retinal images. Images acquired by the flood-illuminated AO system are taken to test the efficiency of this algorithm. We labeled these images both automatically and manually, and compared the results of the two methods. A 94.1% to 96.5% agreement rate between the two methods is achieved in this experiment, which demonstrated the reliability and efficiency of the algorithm.

  17. Compensation for the orbital angular momentum of a vortex beam in turbulent atmosphere by adaptive optics

    Science.gov (United States)

    Li, Nan; Chu, Xiuxiang; Zhang, Pengfei; Feng, Xiaoxing; Fan, ChengYu; Qiao, Chunhong

    2018-01-01

    A method which can be used to compensate for a distorted orbital angular momentum and wavefront of a beam in atmospheric turbulence, simultaneously, has been proposed. To confirm the validity of the method, an experimental setup for up-link propagation of a vortex beam in a turbulent atmosphere has been simulated. Simulation results show that both of the distorted orbital angular momentum and the distorted wavefront of a beam due to turbulence can be compensated by an adaptive optics system with the help of a cooperative beacon at satellite. However, when the number of the lenslet of wavefront sensor (WFS) and the actuators of the deform mirror (DM) is small, satisfactory results cannot be obtained.

  18. Direct adaptive control for nonlinear uncertain dynamical systems

    Science.gov (United States)

    Hayakawa, Tomohisa

    In light of the complex and highly uncertain nature of dynamical systems requiring controls, it is not surprising that reliable system models for many high performance engineering and life science applications are unavailable. In the face of such high levels of system uncertainty, robust controllers may unnecessarily sacrifice system performance whereas adaptive controllers are clearly appropriate since they can tolerate far greater system uncertainty levels to improve system performance. In this dissertation, we develop a Lyapunov-based direct adaptive and neural adaptive control framework that addresses parametric uncertainty, unstructured uncertainty, disturbance rejection, amplitude and rate saturation constraints, and digital implementation issues. Specifically, we consider the following research topics; direct adaptive control for nonlinear uncertain systems with exogenous disturbances; robust adaptive control for nonlinear uncertain systems; adaptive control for nonlinear uncertain systems with actuator amplitude and rate saturation constraints; adaptive reduced-order dynamic compensation for nonlinear uncertain systems; direct adaptive control for nonlinear matrix second-order dynamical systems with state-dependent uncertainty; adaptive control for nonnegative and compartmental dynamical systems with applications to general anesthesia; direct adaptive control of nonnegative and compartmental dynamical systems with time delay; adaptive control for nonlinear nonnegative and compartmental dynamical systems with applications to clinical pharmacology; neural network adaptive control for nonlinear nonnegative dynamical systems; passivity-based neural network adaptive output feedback control for nonlinear nonnegative dynamical systems; neural network adaptive dynamic output feedback control for nonlinear nonnegative systems using tapped delay memory units; Lyapunov-based adaptive control framework for discrete-time nonlinear systems with exogenous disturbances

  19. Shared-hole graph search with adaptive constraints for 3D optic nerve head optical coherence tomography image segmentation

    Science.gov (United States)

    Yu, Kai; Shi, Fei; Gao, Enting; Zhu, Weifang; Chen, Haoyu; Chen, Xinjian

    2018-01-01

    Optic nerve head (ONH) is a crucial region for glaucoma detection and tracking based on spectral domain optical coherence tomography (SD-OCT) images. In this region, the existence of a “hole” structure makes retinal layer segmentation and analysis very challenging. To improve retinal layer segmentation, we propose a 3D method for ONH centered SD-OCT image segmentation, which is based on a modified graph search algorithm with a shared-hole and locally adaptive constraints. With the proposed method, both the optic disc boundary and nine retinal surfaces can be accurately segmented in SD-OCT images. An overall mean unsigned border positioning error of 7.27 ± 5.40 µm was achieved for layer segmentation, and a mean Dice coefficient of 0.925 ± 0.03 was achieved for optic disc region detection. PMID:29541497

  20. Towards an Empathizing and Adaptive Storyteller System

    DEFF Research Database (Denmark)

    Bae, Byung Chull; Brunete, Alberto; Malik, Usman

    2012-01-01

    This paper describes our ongoing effort to build an empathizing and adaptive storyteller system. The system under development aims to utilize emotional expressions generated from an avatar or a humanoid robot in addition to the listener’s responses which are monitored in real time, in order...... to deliver a story in an effective manner. We conducted a pilot study and the results were analyzed in two ways: first, through a survey questionnaire analysis based on the participant’s subjective ratings; second, through automated video analysis based on the participant’s emotional facial expression...

  1. Complex and adaptive dynamical systems a primer

    CERN Document Server

    Gros, Claudius

    2013-01-01

    Complex system theory is rapidly developing and gaining importance, providing tools and concepts central to our modern understanding of emergent phenomena. This primer offers an introduction to this area together with detailed coverage of the mathematics involved. All calculations are presented step by step and are straightforward to follow. This new third edition comes with new material, figures and exercises. Network theory, dynamical systems and information theory, the core of modern complex system sciences, are developed in the first three chapters, covering basic concepts and phenomena like small-world networks, bifurcation theory and information entropy. Further chapters use a modular approach to address the most important concepts in complex system sciences, with the emergence and self-organization playing a central role. Prominent examples are self-organized criticality in adaptive systems, life at the edge of chaos, hypercycles and coevolutionary avalanches, synchronization phenomena, absorbing phase...

  2. Comparison of the marginal adaptation of direct and indirect composite inlay restorations with optical coherence tomography.

    Science.gov (United States)

    Türk, Ayşe Gözde; Sabuncu, Metin; Ünal, Sena; Önal, Banu; Ulusoy, Mübin

    2016-01-01

    The purpose of the study was to use the photonic imaging modality of optical coherence tomography (OCT) to compare the marginal adaptation of composite inlays fabricated by direct and indirect techniques. Class II cavities were prepared on 34 extracted human molar teeth. The cavities were randomly divided into two groups according to the inlay fabrication technique. The first group was directly restored on cavities with a composite (Esthet X HD, Dentsply, Germany) after isolating. The second group was indirectly restored with the same composite material. Marginal adaptations were scanned before cementation with an invisible infrared light beam of OCT (Thorlabs), allowing measurement in 200 µm intervals. Restorations were cemented with a self-adhesive cement resin (SmartCem2, Dentsply), and then marginal adaptations were again measured with OCT. Mean values were statistically compared by using independent-samples t-test and paired samples t-test (pinlays presented statistically smaller marginal discrepancy values than indirect inlays, before (p=0.00001442) and after (p=0.00001466) cementation. Marginal discrepancy values were increased for all restorations after cementation (p=0.00008839, p=0.000000952 for direct and indirect inlays, respectively). The mean marginal discrepancy value of the direct group increased from 56.88±20.04 µm to 91.88±31.7 µm, whereas the indirect group increased from 107.54±35.63 µm to 170.29±54.83 µm. Different techniques are available to detect marginal adaptation of restorations, but the OCT system can give quantitative information about resin cement thickness and its interaction between tooth and restoration in a nondestructive manner. Direct inlays presented smaller marginal discrepancy than indirect inlays. The marginal discrepancy values were increased for all restorations that refer to cement thickness after cementation.

  3. Comparison of the marginal adaptation of direct and indirect composite inlay restorations with optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Ayşe Gözde TÜRK

    Full Text Available ABSTRACT Objective The purpose of the study was to use the photonic imaging modality of optical coherence tomography (OCT to compare the marginal adaptation of composite inlays fabricated by direct and indirect techniques. Material and Methods Class II cavities were prepared on 34 extracted human molar teeth. The cavities were randomly divided into two groups according to the inlay fabrication technique. The first group was directly restored on cavities with a composite (Esthet X HD, Dentsply, Germany after isolating. The second group was indirectly restored with the same composite material. Marginal adaptations were scanned before cementation with an invisible infrared light beam of OCT (Thorlabs, allowing measurement in 200 µm intervals. Restorations were cemented with a self-adhesive cement resin (SmartCem2, Dentsply, and then marginal adaptations were again measured with OCT. Mean values were statistically compared by using independent-samples t-test and paired samples t-test (p<0.05, before and after cementation. Results Direct inlays presented statistically smaller marginal discrepancy values than indirect inlays, before (p=0.00001442 and after (p=0.00001466 cementation. Marginal discrepancy values were increased for all restorations after cementation (p=0.00008839, p=0.000000952 for direct and indirect inlays, respectively. The mean marginal discrepancy value of the direct group increased from 56.88±20.04 µm to 91.88±31.7 µm, whereas the indirect group increased from 107.54±35.63 µm to 170.29±54.83 µm. Different techniques are available to detect marginal adaptation of restorations, but the OCT system can give quantitative information about resin cement thickness and its interaction between tooth and restoration in a nondestructive manner. Conclusions Direct inlays presented smaller marginal discrepancy than indirect inlays. The marginal discrepancy values were increased for all restorations that refer to cement thickness after

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

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  5. Hybrid cognitive engine for radio systems adaptation

    KAUST Repository

    Alqerm, Ismail

    2017-07-20

    Network efficiency and proper utilization of its resources are essential requirements to operate wireless networks in an optimal fashion. Cognitive radio aims to fulfill these requirements by exploiting artificial intelligence techniques to create an entity called cognitive engine. Cognitive engine exploits awareness about the surrounding radio environment to optimize the use of radio resources and adapt relevant transmission parameters. In this paper, we propose a hybrid cognitive engine that employs Case Based Reasoning (CBR) and Decision Trees (DTs) to perform radio adaptation in multi-carriers wireless networks. The engine complexity is reduced by employing DTs to improve the indexing methodology used in CBR cases retrieval. The performance of our hybrid engine is validated using software defined radios implementation and simulation in multi-carrier environment. The system throughput, signal to noise and interference ratio, and packet error rate are obtained and compared with other schemes in different scenarios.

  6. A new optical antennas based on fiber coupling system and aspherical optical system

    Science.gov (United States)

    Wang, Ye; Tian, Shaohua

    2013-08-01

    Space Laser communication is a new technology in recent years of optical communications, optical antenna is a communications front receiving system, compose of the optical antenna receiver, optical fiber coupling lenses. Optical antenna to receive as much as possible the signal light from the target of free space, In this paper, 10.6μm wavelength of infrared light for communication wave, we use spherical mirror and aspheric lens combination of the system, Design of large diameter concave mirror to collect more laser energy, After another spherical convex mirror reflection again to aspherical lens, then coupled into the fiber. The aspheric lens can be a good feature to correct aberration, so this design has less transmission loss and high coupling efficiency. Using Zemax software, we setting reasonable energy analysis and image quality evaluation, design spherical mirrors and aspherical refractive lenses optical system, has good optical performance and economy, can be apply on the atmospheric Laser communication the receiving device.

  7. Optical seismic sensor systems and methods

    Science.gov (United States)

    Beal, A. Craig; Cummings, Malcolm E.; Zavriyev, Anton; Christensen, Caleb A.; Lee, Keun

    2015-12-08

    Disclosed is an optical seismic sensor system for measuring seismic events in a geological formation, including a surface unit for generating and processing an optical signal, and a sensor device optically connected to the surface unit for receiving the optical signal over an optical conduit. The sensor device includes at least one sensor head for sensing a seismic disturbance from at least one direction during a deployment of the sensor device within a borehole of the geological formation. The sensor head includes a frame and a reference mass attached to the frame via at least one flexure, such that movement of the reference mass relative to the frame is constrained to a single predetermined path.

  8. Refined adaptive optics simulation with wide field of view for the E-ELT

    International Nuclear Information System (INIS)

    Chebbo, Manal

    2012-01-01

    Refined simulation tools for wide field AO systems (such as MOAO, MCAO or LTAO) on ELTs present new challenges. Increasing the number of degrees of freedom (scales as the square of the telescope diameter) makes the standard simulation's codes useless due to the huge number of operations to be performed at each step of the Adaptive Optics (AO) loop process. This computational burden requires new approaches in the computation of the DM voltages from WFS data. The classical matrix inversion and the matrix vector multiplication have to be replaced by a cleverer iterative resolution of the Least Square or Minimum Mean Square Error criterion (based on sparse matrices approaches). Moreover, for this new generation of AO systems, concepts themselves will become more complex: data fusion coming from multiple Laser and Natural Guide Stars (LGS / NGS) will have to be optimized, mirrors covering all the field of view associated to dedicated mirrors inside the scientific instrument itself will have to be coupled using split or integrated tomography schemes, differential pupil or/and field rotations will have to be considered, etc. All these new entries should be carefully simulated, analysed and quantified in terms of performance before any implementation in AO systems. For those reasons I developed, in collaboration with the ONERA, a full simulation code, based on iterative solution of linear systems with many parameters (use of sparse matrices). On this basis, I introduced new concepts of filtering and data fusion (LGS / NGS) to effectively manage modes such as tip, tilt and defocus in the entire process of tomographic reconstruction. The code will also eventually help to develop and test complex control laws (Multi-DM and multi-field) who have to manage a combination of adaptive telescope and post-focal instrument including dedicated deformable mirrors. The first application of this simulation tool has been studied in the framework of the EAGLE multi-object spectrograph

  9. Wavefront Reconstruction and Mirror Surface Optimizationfor Adaptive Optics

    Science.gov (United States)

    2014-06-01

    Aberrations: Part II. Bellingham, WA: SPIE Optical Engineering Press, 1998. [21] H. H. Barrett and K. J. Myers , Foundations of Image Science. Hoboken, NJ...optimization in MATLAB,” in Proceedings of CACSD, Taipei, Taiwan, 2004. [Online]. Available: http: //users.isy.liu.se/johanl/yalmip [71] W. L. Briggs , V...E. Henson, and S. F. McCormick, A Multigrid Tutorial. Philadelphia, PA: SIAM, 2000. [72] W. L. Briggs and V. E. Henson, “Wavelets and multigrid

  10. Adaptive optics improves multiphoton super-resolution imaging.

    Science.gov (United States)

    Zheng, Wei; Wu, Yicong; Winter, Peter; Fischer, Robert; Nogare, Damian Dalle; Hong, Amy; McCormick, Chad; Christensen, Ryan; Dempsey, William P; Arnold, Don B; Zimmerberg, Joshua; Chitnis, Ajay; Sellers, James; Waterman, Clare; Shroff, Hari

    2017-09-01

    We improve multiphoton structured illumination microscopy using a nonlinear guide star to determine optical aberrations and a deformable mirror to correct them. We demonstrate our method on bead phantoms, cells in collagen gels, nematode larvae and embryos, Drosophila brain, and zebrafish embryos. Peak intensity is increased (up to 40-fold) and resolution recovered (up to 176 ± 10 nm laterally, 729 ± 39 nm axially) at depths ∼250 μm from the coverslip surface.

  11. Complex and adaptive dynamical systems a primer

    CERN Document Server

    Gros, Claudius

    2015-01-01

    This primer offers readers an introduction to the central concepts that form our modern understanding of complex and emergent behavior, together with detailed coverage of accompanying mathematical methods. All calculations are presented step by step and are easy to follow. This new fourth edition has been fully reorganized and includes new chapters, figures and exercises. The core aspects of modern complex system sciences are presented in the first chapters, covering network theory, dynamical systems, bifurcation and catastrophe theory, chaos and adaptive processes, together with the principle of self-organization in reaction-diffusion systems and social animals. Modern information theoretical principles are treated in further chapters, together with the concept of self-organized criticality, gene regulation networks, hypercycles and coevolutionary avalanches, synchronization phenomena, absorbing phase transitions and the cognitive system approach to the brain. Technical course prerequisites are the standard ...

  12. On the power and offset allocation for rate adaptation of spatial multiplexing in optical wireless MIMO channels

    KAUST Repository

    Park, Kihong

    2013-04-01

    In this paper, we consider resource allocation method in the visible light communication. It is challenging to achieve high data rate due to the limited bandwidth of the optical sources. In order to increase the spectral efficiency, we design a suitable multiple-input multiple-output (MIMO) system utilizing spatial multiplexing based on singular value decomposition and adaptive modulation. More specifically, after explaining why the conventional allocation method in radio frequency MIMO channels cannot be applied directly to the optical intensity channels, we theoretically derive a power allocation method for an arbitrary number of transmit and receive antennas for optical wireless MIMO systems. Based on three key constraints: the nonnegativity of the intensity-modulated signal, the aggregate optical power budget, and the bit error rate requirement, we propose a novel method to allocate the optical power, the offset value, and the modulation size. Based on some selected simulation results, we show that our proposed allocation method gives a better spectral efficiency at the expense of an increased computational complexity in comparison to a simple method that allocates the optical power equally among all the data streams. © 2013 IEEE.

  13. Adaptable data management for systems biology investigations

    Directory of Open Access Journals (Sweden)

    Burdick David

    2009-03-01

    Full Text Available Abstract Background Within research each experiment is different, the focus changes and the data is generated from a continually evolving barrage of technologies. There is a continual introduction of new techniques whose usage ranges from in-house protocols through to high-throughput instrumentation. To support these requirements data management systems are needed that can be rapidly built and readily adapted for new usage. Results The adaptable data management system discussed is designed to support the seamless mining and analysis of biological experiment data that is commonly used in systems biology (e.g. ChIP-chip, gene expression, proteomics, imaging, flow cytometry. We use different content graphs to represent different views upon the data. These views are designed for different roles: equipment specific views are used to gather instrumentation information; data processing oriented views are provided to enable the rapid development of analysis applications; and research project specific views are used to organize information for individual research experiments. This management system allows for both the rapid introduction of new types of information and the evolution of the knowledge it represents. Conclusion Data management is an important aspect of any research enterprise. It is the foundation on which most applications are built, and must be easily extended to serve new functionality for new scientific areas. We have found that adopting a three-tier architecture for data management, built around distributed standardized content repositories, allows us to rapidly develop new applications to support a diverse user community.

  14. Adaptable data management for systems biology investigations

    Science.gov (United States)

    Boyle, John; Rovira, Hector; Cavnor, Chris; Burdick, David; Killcoyne, Sarah; Shmulevich, Ilya

    2009-01-01

    Background Within research each experiment is different, the focus changes and the data is generated from a continually evolving barrage of technologies. There is a continual introduction of new techniques whose usage ranges from in-house protocols through to high-throughput instrumentation. To support these requirements data management systems are needed that can be rapidly built and readily adapted for new usage. Results The adaptable data management system discussed is designed to support the seamless mining and analysis of biological experiment data that is commonly used in systems biology (e.g. ChIP-chip, gene expression, proteomics, imaging, flow cytometry). We use different content graphs to represent different views upon the data. These views are designed for different roles: equipment specific views are used to gather instrumentation information; data processing oriented views are provided to enable the rapid development of analysis applications; and research project specific views are used to organize information for individual research experiments. This management system allows for both the rapid introduction of new types of information and the evolution of the knowledge it represents. Conclusion Data management is an important aspect of any research enterprise. It is the foundation on which most applications are built, and must be easily extended to serve new functionality for new scientific areas. We have found that adopting a three-tier architecture for data management, built around distributed standardized content repositories, allows us to rapidly develop new applications to support a diverse user community. PMID:19265554

  15. Enhancing performance of LCoS-SLM as adaptive optics by using computer-generated holograms modulation software

    Science.gov (United States)

    Tsai, Chun-Wei; Lyu, Bo-Han; Wang, Chen; Hung, Cheng-Chieh

    2017-05-01

    We have already developed multi-function and easy-to-use modulation software that was based on LabVIEW system. There are mainly four functions in this modulation software, such as computer generated holograms (CGH) generation, CGH reconstruction, image trimming, and special phase distribution. Based on the above development of CGH modulation software, we could enhance the performance of liquid crystal on silicon - spatial light modulator (LCoSSLM) as similar as the diffractive optical element (DOE) and use it on various adaptive optics (AO) applications. Through the development of special phase distribution, we are going to use the LCoS-SLM with CGH modulation software into AO technology, such as optical microscope system. When the LCOS-SLM panel is integrated in an optical microscope system, it could be placed on the illumination path or on the image forming path. However, LCOS-SLM provides a program-controllable liquid crystal array for optical microscope. It dynamically changes the amplitude or phase of light and gives the obvious advantage, "Flexibility", to the system

  16. Benefit of adaptive FEC in shared backup path protected elastic optical network.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2015-08-10

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

  18. Design of optically stable image reflector system.

    Science.gov (United States)

    Tsai, Chung-Yu

    2013-08-01

    The design of a partially optically stable (POS) reflector system, in which the exit ray direction and image pose are unchanged as the reflector system rotates about a specific directional vector, was presented in an earlier study by the current group [Appl. Phys. B100, 883-890 (2010)]. The present study further proposes an optically stable image (OSI) reflector system, in which not only is the optical stability property of the POS system retained, but the image position and total ray path length are also fixed. An analytical method is proposed for the design of OSI reflector systems comprising multiple reflectors. The validity of the proposed approach is demonstrated by means of two illustrative examples.

  19. Full-duplex optical communication system

    Science.gov (United States)

    Shay, Thomas M. (Inventor); Hazzard, David A. (Inventor); Horan, Stephen (Inventor); Payne, Jason A. (Inventor)

    2004-01-01

    A method of full-duplex electromagnetic communication wherein a pair of data modulation formats are selected for the forward and return data links respectively such that the forward data electro-magnetic beam serves as a carrier for the return data. A method of encoding optical information is used wherein right-hand and left-hand circular polarizations are assigned to optical information to represent binary states. An application for an earth to low earth orbit optical communications system is presented which implements the full-duplex communication and circular polarization keying modulation format.

  20. Water System Adaptation To Hydrological Changes: Module 7, Adaptation Principles and Considerations

    Science.gov (United States)

    This course will introduce students to the fundamental principles of water system adaptation to hydrological changes, with emphasis on data analysis and interpretation, technical planning, and computational modeling. Starting with real-world scenarios and adaptation needs, the co...

  1. Application of fluidic lens technology to an adaptive holographic optical element see-through autophoropter

    Science.gov (United States)

    Chancy, Carl H.

    A device for performing an objective eye exam has been developed to automatically determine ophthalmic prescriptions. The closed loop fluidic auto-phoropter has been designed, modeled, fabricated and tested for the automatic measurement and correction of a patient's prescriptions. The adaptive phoropter is designed through the combination of a spherical-powered fluidic lens and two cylindrical fluidic lenses that are orientated 45o relative to each other. In addition, the system incorporates Shack-Hartmann wavefront sensing technology to identify the eye's wavefront error and corresponding prescription. Using the wavefront error information, the fluidic auto-phoropter nulls the eye's lower order wavefront error by applying the appropriate volumes to the fluidic lenses. The combination of the Shack-Hartmann wavefront sensor the fluidic auto-phoropter allows for the identification and control of spherical refractive error, as well as cylinder error and axis; thus, creating a truly automated refractometer and corrective system. The fluidic auto-phoropter is capable of correcting defocus error ranging from -20D to 20D and astigmatism from -10D to 10D. The transmissive see-through design allows for the observation of natural scenes through the system at varying object planes with no additional imaging optics in the patient's line of sight. In this research, two generations of the fluidic auto-phoropter are designed and tested; the first generation uses traditional glass optics for the measurement channel. The second generation of the fluidic auto-phoropter takes advantage of the progress in the development of holographic optical elements (HOEs) to replace all the traditional glass optics. The addition of the HOEs has enabled the development of a more compact, inexpensive and easily reproducible system without compromising its performance. Additionally, the fluidic lenses were tested during a National Aeronautics Space Administration (NASA) parabolic flight campaign, to

  2. Adaptive stimulus optimization for sensory systems neuroscience.

    Science.gov (United States)

    DiMattina, Christopher; Zhang, Kechen

    2013-01-01

    In this paper, we review several lines of recent work aimed at developing practical methods for adaptive on-line stimulus generation for sensory neurophysiology. We consider various experimental paradigms where on-line stimulus optimization is utilized, including the classical optimal stimulus paradigm where the goal of experiments is to identify a stimulus which maximizes neural responses, the iso-response paradigm which finds sets of stimuli giving rise to constant responses, and the system identification paradigm where the experimental goal is to estimate and possibly compare sensory processing models. We discuss various theoretical and practical aspects of adaptive firing rate optimization, including optimization with stimulus space constraints, firing rate adaptation, and possible network constraints on the optimal stimulus. We consider the problem of system identification, and show how accurate estimation of non-linear models can be highly dependent on the stimulus set used to probe the network. We suggest that optimizing stimuli for accurate model estimation may make it possible to successfully identify non-linear models which are otherwise intractable, and summarize several recent studies of this type. Finally, we present a two-stage stimulus design procedure which combines the dual goals of model estimation and model comparison and may be especially useful for system identification experiments where the appropriate model is unknown beforehand. We propose that fast, on-line stimulus optimization enabled by increasing computer power can make it practical to move sensory neuroscience away from a descriptive paradigm and toward a new paradigm of real-time model estimation and comparison.

  3. Adaptive Sliding Mode Observer for a Class of Systems

    OpenAIRE

    D.Elleuch; T.Damak

    2010-01-01

    In this paper, the performance of two adaptive observers applied to interconnected systems is studied. The nonlinearity of systems can be written in a fractional form. The first adaptive observer is an adaptive sliding mode observer for a Lipchitz nonlinear system and the second one is an adaptive sliding mode observer having a filtered error as a sliding surface. After comparing their performances throughout the inverted pendulum mounted on a car system, it was shown tha...

  4. Volumetric imaging of rod and cone photoreceptor structure with a combined adaptive optics-optical coherence tomography-scanning laser ophthalmoscope.

    Science.gov (United States)

    Wells-Gray, Elaine M; Choi, Stacey S; Zawadzki, Robert J; Finn, Susanna C; Greiner, Cherry; Werner, John S; Doble, Nathan

    2018-03-01

    We have designed and implemented a dual-mode adaptive optics (AO) imaging system that combines spectral domain optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) for in vivo imaging of the human retina. The system simultaneously acquires SLO frames and OCT B-scans at 60 Hz with an OCT volume acquisition time of 4.2 s. Transverse eye motion measured from the SLO is used to register the OCT B-scans to generate three-dimensional (3-D) volumes. Key optical design considerations include: minimizing system aberrations through the use of off-axis relay telescopes, conjugate pupil plane requirements, and the use of dichroic beam splitters to separate and recombine the OCT and SLO beams around the nonshared horizontal scanning mirrors. To demonstrate system performance, AO-OCT-SLO images and measurements are taken from three normal human subjects ranging in retinal eccentricity from the fovea out to 15-deg temporal and 20-deg superior. Also presented are en face OCT projections generated from the registered 3-D volumes. The ability to acquire high-resolution 3-D images of the human retina in the midperiphery and beyond has clinical importance in diseases, such as retinitis pigmentosa and cone-rod dystrophy. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  5. Management Concerns for Optical Based Filing Systems

    Science.gov (United States)

    1990-03-01

    Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN INFORMATION SYSTEMS from the NAVAL POSTGRADUATE SCHOOL March... social security number (SSN) of an individual may be inadequate if there are many records for an individual. While descriptors from a particular record...displayed. - Source The Hanbook ofOptical Memor Syste s p. 6.0-Z Optical Disk Intitute, 1989 Figure 4. Retrieval Time Factors 42 V. SERVICE RECORD

  6. Scaling of Adaptive Immune System Repertoires

    Science.gov (United States)

    Sethna, Zachary; Elhanati, Yuval; Callan, Curtis

    The adaptive immune system has evolved a stochastic method called VDJ recombination for the purpose of generating the necessary receptor diversity to identify all foreign pathogens. Recent work characterizing the probability distributions of this VDJ recombination process in mouse and human T-cell repertoires shows a massive difference in the corresponding diversities. The increased diversity of the human repertoire is wholly driven by an increase in the average number of nucleotide insertions in VDJ recombination. In this talk the impact of different insertion profiles is quantified and a model for the scaling of such repertoires with respect to the size of the repertoire is laid out.

  7. Demonstration of a vectorial optical field generator with adaptive close loop control

    Science.gov (United States)

    Chen, Jian; Kong, Lingjiang; Zhan, Qiwen

    2017-12-01

    We experimentally demonstrate a vectorial optical field generator (VOF-Gen) with an adaptive close loop control. The close loop control capability is illustrated with the calibration of polarization modulation of the system. To calibrate the polarization ratio modulation, we generate 45° linearly polarized beam and make it propagate through a linear analyzer whose transmission axis is orthogonal to the incident beam. For the retardation calibration, circularly polarized beam is employed and a circular polarization analyzer with the opposite chirality is placed in front of the CCD as the detector. In both cases, the close loop control automatically changes the value of the corresponding calibration parameters in the pre-set ranges to generate the phase patterns applied to the spatial light modulators and records the intensity distribution of the output beam by the CCD camera. The optimized calibration parameters are determined corresponding to the minimum total intensity in each case. Several typical kinds of vectorial optical beams are created with and without the obtained calibration parameters, and the full Stokes parameter measurements are carried out to quantitatively analyze the polarization distribution of the generated beams. The comparisons among these results clearly show that the obtained calibration parameters could remarkably improve the accuracy of the polarization modulation of the VOF-Gen, especially for generating elliptically polarized beam with large ellipticity, indicating the significance of the presented close loop in enhancing the performance of the VOF-Gen.

  8. Intelligent correction of laser beam propagation through turbulent media using adaptive optics

    Science.gov (United States)

    Ko, Jonathan; Wu, Chensheng; Davis, Christopher C.

    2014-10-01

    Adaptive optics methods have long been used by researchers in the astronomy field to retrieve correct images of celestial bodies. The approach is to use a deformable mirror combined with Shack-Hartmann sensors to correct the slightly distorted image when it propagates through the earth's atmospheric boundary layer, which can be viewed as adding relatively weak distortion in the last stage of propagation. However, the same strategy can't be easily applied to correct images propagating along a horizontal deep turbulence path. In fact, when turbulence levels becomes very strong (Cn 2>10-13 m-2/3), limited improvements have been made in correcting the heavily distorted images. We propose a method that reconstructs the light field that reaches the camera, which then provides information for controlling a deformable mirror. An intelligent algorithm is applied that provides significant improvement in correcting images. In our work, the light field reconstruction has been achieved with a newly designed modified plenoptic camera. As a result, by actively intervening with the coherent illumination beam, or by giving it various specific pre-distortions, a better (less turbulence affected) image can be obtained. This strategy can also be expanded to much more general applications such as correcting laser propagation through random media and can also help to improve designs in free space optical communication systems.

  9. Managing Schools as Complex Adaptive Systems: A Strategic Perspective

    Science.gov (United States)

    Fidan, Tuncer; Balci, Ali

    2017-01-01

    This conceptual study examines the analogies between schools and complex adaptive systems and identifies strategies used to manage schools as complex adaptive systems. Complex adaptive systems approach, introduced by the complexity theory, requires school administrators to develop new skills and strategies to realize their agendas in an…

  10. Adaptive Optics Imaging of Pluto-Charon and the Discovery of a Moon aroun d the Asteroid 45 Eugenia: The Potential of Adaptive Optics in Planetary Astrono my

    Science.gov (United States)

    Close, L. M.; Merline, W. J.; Tholen, D.; Owen, T.; Roddier, F.; Dumas, C.

    1999-12-01

    We outline two separate projects which highlight the power of adaptive optics (AO) to aid planetary research. The first project utilized AO to resolve the Pluto-Charon system by producing 0.15" FWHM images. We used the University of Hawaii AO system (Roddier et al. PASP 103, 131,1991) at CFHT to obtain deep (20 min) narrow band images in/out the molecular bands of water and methane ices. Our images confirm that the variation of Pluto's albedo is mainly governed by the presence of methane ice over its surface, resulting in a lower albedo at 2.26 um than at 2.02 um. Our observations confirm also that Charon is mostly covered with water-ice (Buie et al. NATURE 329, 522,1987). See Tholen et al. (ICARUS submitted) for more details on these AO results. In another application of AO, we discovered a moon around asteroid 45 Eugenia by use of the PUEO AO facility at CFHT (Rigaut et al. PASP 110, 152, 1998). With PUEO we preformed a search for asteroidal satellites among two dozen asteroids, achieving moderate Strehl ratios (35%) and FWHM of about 0.12" at H band. During this survey, we detected a faint close companion to 45 Eugenia. The satellite was 6.14 magnitudes (at 1.65 um) fainter and located at most 0.75" from Eugenia. Without the ability of AO (to sharpen the contrast and increase the resolution to 0.1"), the detection of this companion would have been impossible with ground based-telescopes. The companion was found to be in a 1200 km circular orbit with a period of 4.7 days. A more detailed discussion of this new satellite is given by Merline et al. in this volume. Adaptive optics is entering a powerful new age as all the major ground based large telescopes are developing facility AO systems. Planetary astronomy is particularly well posed to take advantage of the diffraction-limited, near-IR images (0.050" FWHM) that will become commonplace at all 8 m facilities in the near future (It is already occurring on the KECK and GEMINI-North telescopes). In particular, we

  11. Data-Adaptable Modeling and Optimization for Runtime Adaptable Systems

    Science.gov (United States)

    2016-06-08

    MONITOR’S REPORT NUMBER(S) 16. SECURITY CLASSIFICATION OF: 19b. TELEPHONE NUMBER (Include area code) The public reporting burden for this collection...often encounter situations in which it is unable to retrieve video or GPS data in remote areas . A data-adaptable approach should enable such an...Farrell, M. Okincha, M. Parmar, and B. Wandell, “Using visible SNR (vSNR) to compare the image quality of pixel binning and digital resizing ,” In Proc

  12. Electro-optical fuel pin identification system

    International Nuclear Information System (INIS)

    Kirchner, T.L.

    1978-09-01

    A prototype Electro-Optical Fuel Pin Identification System referred to as the Fuel Pin Identification System (FPIS) has been developed by the Hanford Engineering Development Laboratory (HEDL) in support of the Fast Flux Test Facility (FFTF) presently under construction at HEDL. The system is designed to remotely read an alpha-numeric identification number that is roll stamped on the top of the fuel pin end cap. The prototype FPIS consists of four major subassemblies: optical read head, digital compression electronics, video display, and line printer

  13. The Adaptive Immune System of Haloferax volcanii

    Directory of Open Access Journals (Sweden)

    Lisa-Katharina Maier

    2015-02-01

    Full Text Available To fight off invading genetic elements, prokaryotes have developed an elaborate defence system that is both adaptable and heritable—the CRISPR-Cas system (CRISPR is short for: clustered regularly interspaced short palindromic repeats and Cas: CRISPR associated. Comprised of proteins and multiple small RNAs, this prokaryotic defence system is present in 90% of archaeal and 40% of bacterial species, and enables foreign intruders to be eliminated in a sequence-specific manner. There are three major types (I–III and at least 14 subtypes of this system, with only some of the subtypes having been analysed in detail, and many aspects of the defence reaction remaining to be elucidated. Few archaeal examples have so far been analysed. Here we summarize the characteristics of the CRISPR-Cas system of Haloferax volcanii, an extremely halophilic archaeon originally isolated from the Dead Sea. It carries a single CRISPR-Cas system of type I-B, with a Cascade like complex composed of Cas proteins Cas5, Cas6b and Cas7. Cas6b is essential for CRISPR RNA (crRNA maturation but is otherwise not required for the defence reaction. A systematic search revealed that six protospacer adjacent motif (PAM sequences are recognised by the Haloferax defence system. For successful invader recognition, a non-contiguous seed sequence of 10 base-pairs between the crRNA and the invader is required.

  14. Control systems in optical fibre industry

    Czech Academy of Sciences Publication Activity Database

    Kostka, František

    1998-01-01

    Roč. 1, č. 4 (1998), s. 195-200 ISSN 1405-5546 Grant - others:AV ČR(CZ) KSK1067601 Projekt 10/96/K:4107 Keywords : control systems * real time systems * microcomputers * optical fibres Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  15. Multiphoton fluorescence microscopy with GRIN objective aberration correction by low order adaptive optics.

    Science.gov (United States)

    Bortoletto, Favio; Bonoli, Carlotta; Panizzolo, Paolo; Ciubotaru, Catalin D; Mammano, Fabio

    2011-01-01

    Graded Index (GRIN) rod microlenses are increasingly employed in the assembly of optical probes for microendoscopy applications. Confocal, two-photon and optical coherence tomography (OCT) based on GRIN optical probes permit in-vivo imaging with penetration depths into tissue up to the centimeter range. However, insertion of the probe can be complicated by the need of several alignment and focusing mechanisms along the optical path. Furthermore, resolution values are generally not limited by diffraction, but rather by optical aberrations within the endoscope probe and feeding optics. Here we describe a multiphoton confocal fluorescence imaging system equipped with a compact objective that incorporates a GRIN probe and requires no adjustment mechanisms. We minimized the effects of aberrations with optical compensation provided by a low-order electrostatic membrane mirror (EMM) inserted in the optical path of the confocal architecture, resulting in greatly enhanced image quality.

  16. Adaptive Control of the Chaotic System via Singular System Approach

    Directory of Open Access Journals (Sweden)

    Yudong Li

    2014-01-01

    Full Text Available This paper deals with the control problem of the chaotic system subject to disturbance. The sliding mode surface is designed by singular system approach, and sufficient condition for convergence is given. Then, the adaptive sliding mode controller is designed to make the state arrive at the sliding mode surface in finite time. Finally, Lorenz system is considered as an example to show the effectiveness of the proposed method.

  17. Fiber optical parametric amplifiers in optical communication systems

    Science.gov (United States)

    Marhic (†), Michel E; Andrekson, Peter A; Petropoulos, Periklis; Radic, Stojan; Peucheret, Christophe; Jazayerifar, Mahmoud

    2015-01-01

    The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time-division multiplexed formats. High-quality mid-span spectral inversion has been demonstrated at 0.64 Tb/s, avoiding electronic dispersion compensation. All-optical amplitude regeneration of amplitude-modulated signals has been performed, while PSAs have been used to demonstrate phase regeneration of phase-modulated signals. A PSA with 1.1-dB noise figure has been demonstrated, and preliminary wavelength-division multiplexing experiments have been performed with PSAs. 512 Gb/s have been transmitted over 6,000 km by periodic phase conjugation. Simulations indicate that PIAs could reach data rate x reach products in excess of 14,000 Tb/s × km in realistic wavelength-division multiplexed long-haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long-haul communication networks are discussed. PMID:25866588

  18. Optical Soliton Simulation in Optical Fibers by OptiSystem

    Science.gov (United States)

    Gaik Tay, Kim; Huong Kah Ching, Audrey; Loi, Wei Sen; Tiong Ong, Chee

    2017-08-01

    Fiber optic communication is often known to offer higher frequency transmission of signals with greater bit rate and larger data carrying capacity over a long distance with lower loss and interference as compared to copper wire electrical communication. However, several factors that would affect the performance of an optical fiber transmission are such as group velocity dispersion (GVD), fiber loss and also self-phase modulation (SPM). In this paper, the effects of GVD, SPM, optical soliton formation and fiber loss are simulated using OptiSystem 14. It is found that GVD broaden pulse in temporal domain without modifying its spectrum. Meanwhile, SPM creates chirp in spectrum with its temporal profile maintained. This work concluded that a balance between the GVD and SPM is essential to form solitonthat is able to travel for a long distance without being distorted. It is also found that the decrease in the amplitude of the soliton is dependent on the fiber loss and this decay in the signal increases with the propagation distance.

  19. Contrarian behavior in a complex adaptive system

    Science.gov (United States)

    Liang, Y.; An, K. N.; Yang, G.; Huang, J. P.

    2013-01-01

    Contrarian behavior is a kind of self-organization in complex adaptive systems (CASs). Here we report the existence of a transition point in a model resource-allocation CAS with contrarian behavior by using human experiments, computer simulations, and theoretical analysis. The resource ratio and system predictability serve as the tuning parameter and order parameter, respectively. The transition point helps to reveal the positive or negative role of contrarian behavior. This finding is in contrast to the common belief that contrarian behavior always has a positive role in resource allocation, say, stabilizing resource allocation by shrinking the redundancy or the lack of resources. It is further shown that resource allocation can be optimized at the transition point by adding an appropriate size of contrarians. This work is also expected to be of value to some other fields ranging from management and social science to ecology and evolution.

  20. Atomic switch networks as complex adaptive systems

    Science.gov (United States)

    Scharnhorst, Kelsey S.; Carbajal, Juan P.; Aguilera, Renato C.; Sandouk, Eric J.; Aono, Masakazu; Stieg, Adam Z.; Gimzewski, James K.

    2018-03-01

    Complexity is an increasingly crucial aspect of societal, environmental and biological phenomena. Using a dense unorganized network of synthetic synapses it is shown that a complex adaptive system can be physically created on a microchip built especially for complex problems. These neuro-inspired atomic switch networks (ASNs) are a dynamic system with inherent and distributed memory, recurrent pathways, and up to a billion interacting elements. We demonstrate key parameters describing self-organized behavior such as non-linearity, power law dynamics, and multistate switching regimes. Device dynamics are then investigated using a feedback loop which provides control over current and voltage power-law behavior. Wide ranging prospective applications include understanding and eventually predicting future events that display complex emergent behavior in the critical regime.

  1. CMAC-based adaptive backstepping synchronization of uncertain chaotic systems

    International Nuclear Information System (INIS)

    Lin, C.-M.; Peng, Y.-F.; Lin, M.-H.

    2009-01-01

    This study proposes an adaptive backstepping control system for synchronizing uncertain chaotic system by using cerebellar model articulation controller (CMAC). CMAC is a nonlinear network with simple computation, good generalization capability and fast learning property. The proposed CMAC-based adaptive backstepping control (CABC) system uses backstepping method and adaptive cerebellar model articulation controller (ACMAC) for synchronizing uncertain chaotic system. Finally, simulation results for the Genesio system are presented to illustrate the effectiveness of the proposed control system.

  2. Neptune’s zonal winds from near-IR Keck adaptive optics imaging in August 2001

    NARCIS (Netherlands)

    Martin, S.C.; De Pater, I.; Marcus, P.

    2011-01-01

    We present H-band (1.4–1.8 ?m) images of Neptune with a spatial resolution of ?0.06?, taken with the W.M. Keck II telescope using the slit-viewing camera (SCAM) of the NIRSPEC instrument backed with Adaptive Optics. Images with 60-second integration times span 4 hours each on UT 20 and 21 August,

  3. Characterization of a tunable astigmatic fluidic lens with adaptive optics correction for compact phoropter application

    Science.gov (United States)

    Fuh, Yiin-Kuen; Huang, Chieh-Tse

    2014-07-01

    Fluidically controlled lenses which adaptively correct prescribed refractive error without mechanically moving parts are extensively applied in the ophthalmic applications. Capable of variable-focusing properties, however, the associated aberrations due to curvature change and refractive index mismatch can inherently degrade image quality severely. Here we present the experimental study of the aberrations in tunable astigmatic lens and use of adaptive optics to compensate for the wavefront errors. Characterization of the optical properties of the individual lenses is carried out by Shack-Hartmann measurements. An adaptive optics (AO) based scheme is demonstrated for three injected fluidic volumes, resulting in a substantial reduction of the wavefront errors from -0.12, -0.25, -0.32 to 0.01, -0.01, -0.20 μm, respectively, corresponding to the optical power tenability of 0.83 to 1.84 D. Furthermore, an integrated optical phoroptor consisting of adjustable astigmatic lenses and AO correction is demonstrated such that an induced refraction error of -1 D cylinder at 180° of a model eye vision is experimentally corrected.

  4. Adaptive optics in spinning disk microscopy: improved contrast and brightness by a simple and fast method.

    Science.gov (United States)

    Fraisier, V; Clouvel, G; Jasaitis, A; Dimitrov, A; Piolot, T; Salamero, J

    2015-09-01

    Multiconfocal microscopy gives a good compromise between fast imaging and reasonable resolution. However, the low intensity of live fluorescent emitters is a major limitation to this technique. Aberrations induced by the optical setup, especially the mismatch of the refractive index and the biological sample itself, distort the point spread function and further reduce the amount of detected photons. Altogether, this leads to impaired image quality, preventing accurate analysis of molecular processes in biological samples and imaging deep in the sample. The amount of detected fluorescence can be improved with adaptive optics. Here, we used a compact adaptive optics module (adaptive optics box for sectioning optical microscopy), which was specifically designed for spinning disk confocal microscopy. The module overcomes undesired anomalies by correcting for most of the aberrations in confocal imaging. Existing aberration detection methods require prior illumination, which bleaches the sample. To avoid multiple exposures of the sample, we established an experimental model describing the depth dependence of major aberrations. This model allows us to correct for those aberrations when performing a z-stack, gradually increasing the amplitude of the correction with depth. It does not require illumination of the sample for aberration detection, thus minimizing photobleaching and phototoxicity. With this model, we improved both signal-to-background ratio and image contrast. Here, we present comparative studies on a variety of biological samples. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  5. Optical fiber telecommunications systems and networks

    CERN Document Server

    Kaminow, Ivan; Willner, Alan E

    2013-01-01

    Optical Fiber Telecommunications VI (A&B) is the sixth in a series that has chronicled the progress in the R&D of lightwave communications since the early 1970s. Written by active authorities from academia and industry, this edition brings a fresh look to many essential topics, including devices, subsystems, systems and networks. A central theme is the enabling of high-bandwidth communications in a cost-effective manner for the development of customer applications. These volumes are an ideal reference for R&D engineers and managers, optical systems implementers, university researchers and s

  6. Adaptive restoration of a partially coherent blurred image using an all-optical feedback interferometer with a liquid-crystal device.

    Science.gov (United States)

    Shirai, Tomohiro; Barnes, Thomas H

    2002-02-01

    A liquid-crystal adaptive optics system using all-optical feedback interferometry is applied to partially coherent imaging through a phase disturbance. A theoretical analysis based on the propagation of the cross-spectral density shows that the blurred image due to the phase disturbance can be restored, in principle, irrespective of the state of coherence of the light illuminating the object. Experimental verification of the theory has been performed for two cases when the object to be imaged is illuminated by spatially coherent light originating from a He-Ne laser and by spatially incoherent white light from a halogen lamp. We observed in both cases that images blurred by the phase disturbance were successfully restored, in agreement with the theory, immediately after the adaptive optics system was activated. The origin of the deviation of the experimental results from the theory, together with the effect of the feedback misalignment inherent in our optical arrangement, is also discussed.

  7. Self-adaptive iris image acquisition system

    Science.gov (United States)

    Dong, Wenbo; Sun, Zhenan; Tan, Tieniu; Qiu, Xianchao

    2008-03-01

    Iris image acquisition is the fundamental step of the iris recognition, but capturing high-resolution iris images in real-time is very difficult. The most common systems have small capture volume and demand users to fully cooperate with machines, which has become the bottleneck of iris recognition's application. In this paper, we aim at building an active iris image acquiring system which is self-adaptive to users. Two low resolution cameras are co-located in a pan-tilt-unit (PTU), for face and iris image acquisition respectively. Once the face camera detects face region in real-time video, the system controls the PTU to move towards the eye region and automatically zooms, until the iris camera captures an clear iris image for recognition. Compared with other similar works, our contribution is that we use low-resolution cameras, which can transmit image data much faster and are much cheaper than the high-resolution cameras. In the system, we use Haar-like cascaded feature to detect faces and eyes, linear transformation to predict the iris camera's position, and simple heuristic PTU control method to track eyes. A prototype device has been established, and experiments show that our system can automatically capture high-quality iris image in the range of 0.6m×0.4m×0.4m in average 3 to 5 seconds.

  8. Cone and Rod Loss in Stargardt Disease Revealed by Adaptive Optics Scanning Light Ophthalmoscopy

    Science.gov (United States)

    Song, Hongxin; Rossi, Ethan A.; Latchney, Lisa; Bessette, Angela; Stone, Edwin; Hunter, Jennifer J.; Williams, David R.; Chung, Mina

    2015-01-01

    Importance Stargardt disease (STGD1) is characterized by macular atrophy and flecks in the retinal pigment epithelium. The causative ABCA4 gene encodes a protein localizing to photoreceptor outer segments. The pathologic steps by which ABCA4 mutations lead to clinically detectable retinal pigment epithelium changes remain unclear. We investigated early STGD1 using adaptive optics scanning light ophthalmoscopy. Observations Adaptive optics scanning light ophthalmoscopy imaging of 2 brothers with early STGD1 and their unaffected parents was compared with conventional imaging. Cone and rod spacing were increased in both patients (P optics scanning light ophthalmoscopy reveals increased cone and rod spacing in areas that appear normal in conventional images, suggesting that photoreceptor loss precedes clinically detectable retinal pigment epithelial disease in STGD1. PMID:26247787

  9. Adaptive optics via pupil segmentation for high-resolution imaging in biological tissues.

    Science.gov (United States)

    Ji, Na; Milkie, Daniel E; Betzig, Eric

    2010-02-01

    Biological specimens are rife with optical inhomogeneities that seriously degrade imaging performance under all but the most ideal conditions. Measuring and then correcting for these inhomogeneities is the province of adaptive optics. Here we introduce an approach to adaptive optics in microscopy wherein the rear pupil of an objective lens is segmented into subregions, and light is directed individually to each subregion to measure, by image shift, the deflection faced by each group of rays as they emerge from the objective and travel through the specimen toward the focus. Applying our method to two-photon microscopy, we could recover near-diffraction-limited performance from a variety of biological and nonbiological samples exhibiting aberrations large or small and smoothly varying or abruptly changing. In particular, results from fixed mouse cortical slices illustrate our ability to improve signal and resolution to depths of 400 microm.

  10. Live imaging using adaptive optics with fluorescent protein guide-stars.

    Science.gov (United States)

    Tao, Xiaodong; Crest, Justin; Kotadia, Shaila; Azucena, Oscar; Chen, Diana C; Sullivan, William; Kubby, Joel

    2012-07-02

    Spatially and temporally dependent optical aberrations induced by the inhomogeneous refractive index of live samples limit the resolution of live dynamic imaging. We introduce an adaptive optical microscope with a direct wavefront sensing method using a Shack-Hartmann wavefront sensor and fluorescent protein guide-stars for live imaging. The results of imaging Drosophila embryos demonstrate its ability to correct aberrations and achieve near diffraction limited images of medial sections of large Drosophila embryos. GFP-polo labeled centrosomes can be observed clearly after correction but cannot be observed before correction. Four dimensional time lapse images are achieved with the correction of dynamic aberrations. These studies also demonstrate that the GFP-tagged centrosome proteins, Polo and Cnn, serve as excellent biological guide-stars for adaptive optics based microscopy.

  11. Optical Navigation System, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for a flexible navigation system for deep space operations that does not require GPS measurements. The navigation solution is computed using an...

  12. Wavefront sensorless adaptive optics OCT with the DONE algorithm forin vivohuman retinal imaging [Invited].

    Science.gov (United States)

    Verstraete, Hans R G W; Heisler, Morgan; Ju, Myeong Jin; Wahl, Daniel; Bliek, Laurens; Kalkman, Jeroen; Bonora, Stefano; Jian, Yifan; Verhaegen, Michel; Sarunic, Marinko V

    2017-04-01

    In this report, which is an international collaboration of OCT, adaptive optics, and control research, we demonstrate the Data-based Online Nonlinear Extremum-seeker (DONE) algorithm to guide the image based optimization for wavefront sensorless adaptive optics (WFSL-AO) OCT for in vivo human retinal imaging. The ocular aberrations were corrected using a multi-actuator adaptive lens after linearization of the hysteresis in the piezoelectric actuators. The DONE algorithm succeeded in drastically improving image quality and the OCT signal intensity, up to a factor seven, while achieving a computational time of 1 ms per iteration, making it applicable for many high speed applications. We demonstrate the correction of five aberrations using 70 iterations of the DONE algorithm performed over 2.8 s of continuous volumetric OCT acquisition. Data acquired from an imaging phantom and in vivo from human research volunteers are presented.

  13. Adaptive oriented PDEs filtering methods based on new controlling speed function for discontinuous optical fringe patterns

    Science.gov (United States)

    Zhou, Qiuling; Tang, Chen; Li, Biyuan; Wang, Linlin; Lei, Zhenkun; Tang, Shuwei

    2018-01-01

    The filtering of discontinuous optical fringe patterns is a challenging problem faced in this area. This paper is concerned with oriented partial differential equations (OPDEs)-based image filtering methods for discontinuous optical fringe patterns. We redefine a new controlling speed function to depend on the orientation coherence. The orientation coherence can be used to distinguish the continuous regions and the discontinuous regions, and can be calculated by utilizing fringe orientation. We introduce the new controlling speed function to the previous OPDEs and propose adaptive OPDEs filtering models. According to our proposed adaptive OPDEs filtering models, the filtering in the continuous and discontinuous regions can be selectively carried out. We demonstrate the performance of the proposed adaptive OPDEs via application to the simulated and experimental fringe patterns, and compare our methods with the previous OPDEs.

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

    Science.gov (United States)

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

    2016-01-01

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

  15. Meta-Adaptation Strategies for Adaptation in Cyber-Physical Systems

    OpenAIRE

    Huječek, Adam

    2016-01-01

    When designing a complex Cyber-Physical System it is often impossible to foresee all potential situations in advance and prepare corresponding tactics to adapt to the changes in dynamic environment. This greatly hurts the system's resilience and dependability. All kinds of trouble can rise from situations that lie beyond the expected "envelope of adaptability" from malfunction of one component to failure of the whole system. Self-adaptation approaches are typically limited in choosing a tacti...

  16. ADAPTIVE FULL-SPECTRUM SOLOR ENERGY SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Byard D. Wood

    2004-04-01

    This RD&D project is a three year team effort to develop a hybrid solar lighting (HSL) system that transports solar light from a paraboloidal dish concentrator to a luminaire via a large core polymer fiber optic. The luminaire can be a device to distribute sunlight into a space for the production of algae or it can be a device that is a combination of solar lighting and electric lighting. A benchmark prototype system has been developed to evaluate the HSL system. Sunlight is collected using a one-meter paraboloidal concentrator dish with two-axis tracking. A secondary mirror consisting of eight planar-segmented mirrors directs the visible part of the spectrum to eight fibers (receiver) and subsequently to eight luminaires. This results in about 8,200 lumens incident at each fiber tip. Each fiber can illuminate about 16.7 m{sup 2} (180 ft{sup 2}) of office space. The IR spectrum is directed to a thermophotovoltaic (TPV) array to produce electricity. During this reporting period, the project team made advancements in the design of the second generation (Alpha) system. For the Alpha system, the eight individual 12 mm fibers have been replaced with a centralized bundle of 3 mm fibers. The TRNSYS Full-Spectrum Solar Energy System model has been updated and new components have been added. The TPV array and nonimaging device have been tested and progress has been made in the fiber transmission models. A test plan was developed for both the high-lumen tests and the study to determine the non-energy benefits of daylighting. The photobioreactor team also made major advancements in the testing of model scale and bench top lab-scale systems.

  17. Specification and Generation of Adapters for System Integration

    NARCIS (Netherlands)

    Mooij, A.J.; Voorhoeve, M.

    2013-01-01

    Large systems-of-systems are developed by integrating several smaller systems that have been developed independently. System integration often requires adaptation mechanisms for bridging any technical incompatibilities between the systems. In order to develop adapters in a faster way, we study ways

  18. Adaptive neuro-fuzzy estimation of optimal lens system parameters

    Science.gov (United States)

    Petković, Dalibor; Pavlović, Nenad T.; Shamshirband, Shahaboddin; Mat Kiah, Miss Laiha; Badrul Anuar, Nor; Idna Idris, Mohd Yamani

    2014-04-01

    Due to the popularization of digital technology, the demand for high-quality digital products has become critical. The quantitative assessment of image quality is an important consideration in any type of imaging system. Therefore, developing a design that combines the requirements of good image quality is desirable. Lens system design represents a crucial factor for good image quality. Optimization procedure is the main part of the lens system design methodology. Lens system optimization is a complex non-linear optimization task, often with intricate physical constraints, for which there is no analytical solutions. Therefore lens system design provides ideal problems for intelligent optimization algorithms. There are many tools which can be used to measure optical performance. One very useful tool is the spot diagram. The spot diagram gives an indication of the image of a point object. In this paper, one optimization criterion for lens system, the spot size radius, is considered. This paper presents new lens optimization methods based on adaptive neuro-fuzzy inference strategy (ANFIS). This intelligent estimator is implemented using Matlab/Simulink and the performances are investigated.

  19. NASA Laser Communications with Adaptive Optics and Linear Mode Photon Counting, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In this effort, the Optical Sciences Company (tOSC) and Raytheon Vision Systems (RVS) will team to provide NASA with a long range laser communications system for...

  20. Adaptive Optics Simulation for the World's Largest Telescope on Multicore Architectures with Multiple GPUs

    KAUST Repository

    Ltaief, Hatem

    2016-06-02

    We present a high performance comprehensive implementation of a multi-object adaptive optics (MOAO) simulation on multicore architectures with hardware accelerators in the context of computational astronomy. This implementation will be used as an operational testbed for simulating the de- sign of new instruments for the European Extremely Large Telescope project (E-ELT), the world\\'s biggest eye and one of Europe\\'s highest priorities in ground-based astronomy. The simulation corresponds to a multi-step multi-stage pro- cedure, which is fed, near real-time, by system and turbulence data coming from the telescope environment. Based on the PLASMA library powered by the OmpSs dynamic runtime system, our implementation relies on a task-based programming model to permit an asynchronous out-of-order execution. Using modern multicore architectures associated with the enormous computing power of GPUS, the resulting data-driven compute-intensive simulation of the entire MOAO application, composed of the tomographic reconstructor and the observing sequence, is capable of coping with the aforementioned real-time challenge and stands as a reference implementation for the computational astronomy community.

  1. System for diffusing light from an optical fiber or light guide

    Science.gov (United States)

    Maitland, Duncan J [Pleasant Hill, CA; Wilson, Thomas S [San Leandro, CA; Benett, William J [Livermore, CA; Small, IV, Ward [

    2008-06-10

    A system for diffusing light from an optical fiber wherein the optical fiber is coupled to a light source, comprising forming a polymer element adapted to be connected to the optical fiber and incorporating a scattering element with the polymer element wherein the scattering element diffuses the light from the polymer element. The apparatus of the present invention comprises a polymer element operatively connected to the optical fiber and a scattering element operatively connected with the shape polymer element that diffuses the light from the polymer element.

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

    CSIR Research Space (South Africa)

    Long, CS

    2008-03-01

    Full Text Available degree of freedom Fig. 5. Quadrilateral axisymmetric element with rotational degrees of freedom. The variational formulation of these elements employs the skew-symmetric part of the stress tensor as a Lagrange multiplier to enforce the continuum... mechanics definition of rotations in terms of displacement gradient. The stress tensor is therefore not a priori assumed to be symmetric. The finite element implementation starts with an eight-node ‘base element’ in the local coordinate system. The four...

  3. Precise Prediction of Optical Performance for Near Infrared Instrument Using Adaptive Fitting Line

    OpenAIRE

    Kyeongyeon Ko; Jeong-Yeol Han; Jakyoung Nah; Heeyoung Oh; In-Soo Yuk; Chan Park; Moo-Young Chun; Jae Sok Oh; Kang-Min Kim; Hanshin Lee; Ueejeong Jeong; Daniel T. Jaffe

    2013-01-01

    Infrared optical systems are operated at low temperature and vacuum (LT-V) condition, whereas the assembly and alignment are performed at room temperature and non-vacuum (RT-NV) condition. The differences in temperature and pressure between assembly/alignment environments and operation environment change the physical characteristics of optical and opto-mechanical parts (e.g., thickness, height, length, curvature, and refractive index), and the resultant optical performance changes...

  4. Adaptive Systems in Education: A Review and Conceptual Unification

    Science.gov (United States)

    Wilson, Chunyu; Scott, Bernard

    2017-01-01

    Purpose: The purpose of this paper is to review the use of adaptive systems in education. It is intended to be a useful introduction for the non-specialist reader. Design/methodology/approach: A distinction is made between intelligent tutoring systems (ITSs) and adaptive hypermedia systems (AHSs). The two kinds of system are defined, compared and…

  5. Optical countermeasures against CLOS weapon systems

    Science.gov (United States)

    Toet, Alexander; Benoist, Koen W.; van Lingen, Joost N. J.; Schleijpen, H. Ric M. A.

    2013-10-01

    There are many weapon systems in which a human operator acquires a target, tracks it and designates it. Optical countermeasures against this type of systems deny the operator the possibility to fulfill this visual task. We describe the different effects that result from stimulation of the human visual system with high intensity (visible) light, and the associated potential operational impact. Of practical use are flash blindness, where an intense flash of light produces a temporary "blind-spot" in (part of) the visual field, flicker distraction, where strong intensity and/or color changes at a discomfortable frequency are produced, and disability glare where a source of light leads to contrast reduction. Hence there are three possibilities to disrupt the visual task of an operator with optical countermeasures such as flares or lasers or a combination of these; namely, by an intense flash of light, by an annoying light flicker or by a glare source. A variety of flares for this purpose is now available or under development: high intensity flash flares, continuous burning flares or strobe flares which have an oscillating intensity. The use of flare arrays seems particularly promising as an optical countermeasure. Lasers are particularly suited to interfere with human vision, because they can easily be varied in intensity, color and size, but they have to be directed at the (human) target, and issues like pointing and eye-safety have to be taken into account. Here we discuss the design issues and the operational impact of optical countermeasures against human operators.

  6. Scanning Long-wave Optical Test System: a new ground optical surface slope test system

    Science.gov (United States)

    Su, Tianquan; Park, Won Hyun; Parks, Robert E.; Su, Peng; Burge, James H.

    2011-09-01

    The scanning long-wave optical test system (SLOTS) is under development at the University of Arizona to provide rapid and accurate measurements of aspherical optical surfaces during the grinding stage. It is based on the success of the software configurable optical test system (SCOTS) which uses visible light to measure surface slopes. Working at long wave infrared (LWIR, 7-14 μm), SLOTS measures ground optical surface slopes by viewing the specular reflection of a scanning hot wire. A thermal imaging camera collects data while motorized stages scan the wire through the field. Current experiments show that the system can achieve a high precision at micro-radian level with fairly low cost equipment. The measured surface map is comparable with interferometer for slow optics. This IR system could be applied early in the grinding stage of fabrication of large telescope mirrors to minimize the surface shape error imparted during processing. This advantage combined with the simplicity of the optical system (no null optics, no high power carbon dioxide laser) would improve the efficiency and shorten the processing time.

  7. Automatic design of optical systems by digital computer

    Science.gov (United States)

    Casad, T. A.; Schmidt, L. F.

    1967-01-01

    Computer program uses geometrical optical techniques and a least squares optimization method employing computing equipment for the automatic design of optical systems. It evaluates changes in various optical parameters, provides comprehensive ray-tracing, and generally determines the acceptability of the optical system characteristics.

  8. Optical fiber-applied radiation detection system

    International Nuclear Information System (INIS)

    Nishiura, Ryuichi; Uranaka, Yasuo; Izumi, Nobuyuki

    2001-01-01

    A technique to measure radiation by using plastic scintillation fibers doped radiation fluorescent (scintillator) to plastic optical fiber for a radiation sensor, was developed. The technique contains some superiority such as high flexibility due to using fibers, relatively easy large area due to detecting portion of whole of fibers, and no electromagnetic noise effect due to optical radiation detection and signal transmission. Measurable to wide range of and continuous radiation distribution along optical fiber cable at a testing portion using scintillation fiber and flight time method, the optical fiber-applied radiation sensing system can effectively monitor space radiation dose or apparatus operation condition monitoring. And, a portable type scintillation optical fiber body surface pollution monitor can measure pollution concentration of radioactive materials attached onto body surface by arranging scintillation fiber processed to a plate with small size and flexibility around a man to be tested. Here were described on outline and fundamental properties of various application products using these plastic scintillation fiber. (G.K.)

  9. CHARACTERIZING PHOTORECEPTOR CHANGES IN ACUTE POSTERIOR MULTIFOCAL PLACOID PIGMENT EPITHELIOPATHY USING ADAPTIVE OPTICS.

    Science.gov (United States)

    Roberts, Philipp K; Nesper, Peter L; Onishi, Alex C; Skondra, Dimitra; Jampol, Lee M; Fawzi, Amani A

    2018-01-01

    To characterize lesions of acute posterior multifocal placoid pigment epitheliopathy (APMPPE) by multimodal imaging including adaptive optics scanning laser ophthalmoscopy (AOSLO). We included patients with APMPPE at different stages of evolution of the placoid lesions. Color fundus photography, spectral domain optical coherence tomography, infrared reflectance, fundus autofluorescence, and AOSLO images were obtained and registered to correlate microstructural changes. Eight eyes of four patients (two women) were included and analyzed by multimodal imaging. Photoreceptor reflectivity within APMPPE lesions was more heterogeneous than in adjacent healthy areas. Hyperpigmentation on color fundus photography appeared hyperreflective on infrared reflectance and on AOSLO. Irregularity of the interdigitation zone and the photoreceptor inner and outer segment junctions (IS/OS) on spectral domain optical coherence tomography was associated with photoreceptor hyporeflectivity on AOSLO. Interruption of the interdigitation zone or IS/OS was associated with loss of photoreceptor reflectivity on AOSLO. Irregularities in the reflectivity of the photoreceptor mosaic are visible on AOSLO even in inactive APMPPE lesions, where the photoreceptor bands on spectral domain optical coherence tomography have recovered. Adaptive optics scanning laser ophthalmoscopy combined with multimodal imaging has the potential to enhance our understanding of photoreceptor involvement in APMPPE.

  10. Programmable Ultra-Lightweight System Adaptable Radio

    Science.gov (United States)

    Werkheiser, Arthur

    2015-01-01

    The programmable ultra-lightweight system adaptable radio (PULSAR) is a NASA Marshall Space Flight Center transceiver designed for the CubeSat market, but has the potential for other markets. The PULSAR project aims to reduce size, weight, and power while increasing telemetry data rate. The current version of the PULSAR has a mass of 2.2 kg and a footprint of 10.8 cm2. The height depends on the specific configuration. The PULSAR S-Band Communications Subsystem is an S- and X-band transponder system comprised of a receiver/detector (receiver) element, a transmitter element(s), and related power distribution, command, control, and telemetry element for operation and information interfaces. It is capable of receiving commands, encoding and transmitting telemetry, as well as providing tracking data in a manner compatible with Earthbased ground stations, near Earth network, and deep space network station resources. The software-defined radio's (SDR's) data format characteristics can be defined and reconfigured during spaceflight or prior to launch. The PULSAR team continues to evolve the SDR to improve the performance and form factor to meet the requirements that the CubeSat market space requires. One of the unique features is that the actual radio design can change (somewhat), but not require any hardware modifications due to the use of field programmable gate arrays.

  11. Biofeedback systems and adaptive control hemodialysis treatment

    Directory of Open Access Journals (Sweden)

    Azar Ahmad

    2008-01-01

    Full Text Available On-line monitoring devices to control functions such as volume, body temperature, and ultrafiltration, were considered more toys than real tools for routine clinical application. However, bio-feedback blood volume controlled hemodialysis (HD is now possible in routine dialysis, allowing the delivery of a more physiologically acceptable treatment. This system has proved to reduce the incidence of intra-HD hypotension episodes significantly. Ionic dialysance and the patient′s plasma conductivity can be calculated easily from on-line measurements at two different steps of dialysate conductivity. A bio-feedback system has been devised to calculate the patient′s plasma conductivity and modulate the conductivity of the dialysate continuously in order to achieve a desired end-dialysis patient plasma conductivity corresponding to a desired end-dialysis plasma sodium concentration. Another bio-feedback system can control the body tempe-rature by measuring it at the arterial and venous lines of the extra-corporeal circuit, and then modulating the dialysate temperature in order to stabilize the patients′ temperature at constant values that result in improved intra-HD cardiovascular stability. The module can also be used to quantify vascular access recirculation. Finally, the simultaneous computer control of ultrafiltration has proven the most effective means for automatic blood pressure stabilization during hemo-dialysis treatment. The application of fuzzy logic in the blood-pressure-guided biofeedback con-trol of ultrafiltration during hemodialysis is able to minimize HD-induced hypotension. In con-clusion, online monitoring and adaptive control of the patient during the dialysis session using the bio-feedback systems is expected to render the process of renal replacement therapy more physiological and less eventful.

  12. Fuzzy-Based Adaptive Hybrid Burst Assembly Technique for Optical Burst Switched Networks

    Directory of Open Access Journals (Sweden)

    Abubakar Muhammad Umaru

    2014-01-01

    Full Text Available The optical burst switching (OBS paradigm is perceived as an intermediate switching technology for future all-optical networks. Burst assembly that is the first process in OBS is the focus of this paper. In this paper, an intelligent hybrid burst assembly algorithm that is based on fuzzy logic is proposed. The new algorithm is evaluated against the traditional hybrid burst assembly algorithm and the fuzzy adaptive threshold (FAT burst assembly algorithm via simulation. Simulation results show that the proposed algorithm outperforms the hybrid and the FAT algorithms in terms of burst end-to-end delay, packet end-to-end delay, and packet loss ratio.

  13. Enhanced resolution through thick tissue with structured illumination and adaptive optics.

    Science.gov (United States)

    Thomas, Benjamin; Wolstenholme, Adrian; Chaudhari, Snehal N; Kipreos, Edward T; Kner, Peter

    2015-02-01

    Structured illumination microscopy provides twice the linear resolution of conventional fluorescence microscopy, but in thick samples, aberrations degrade the performance and limit the resolution. Here, we demonstrate structured illumination microscopy through 35 μm of tissue using adaptive optics (AO) to correct aberrations resulting in images with a resolution of 140 nm. We report a 60% minimum improvement in the signal-to-noise ratio of the structured illumination reconstruction through thick tissue by correction with AO. © 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

  14. A new sensitive system for measurement of thermally and optically stimulated luminescence

    DEFF Research Database (Denmark)

    Markey, B.G.; Bøtter-Jensen, L.; Poolton, N.R.J.

    1996-01-01

    optics of the system with a combination of ellipsoidal mirrors and light guides, which also serve to make the system more flexible in choice of excitation source when OSL measurements are required. A variety of new light sources might be employed, adapted to allow the most efficient wavelengths...

  15. Cornea Optical Topographical Scan System (COTSS)

    Science.gov (United States)

    1986-01-01

    The Cornea Optical Topographical Scan System (COTSS) is an instrument designed for use by opthalmologist to aid in performing surgical procedures such as radial keratotomy and to provide quick accurate data to aid in prescribing contact lenses and eyeglasses. A breadboard of the system was built and demonstrated in June of 1984. Additional refinements to the breadboard are needed to meet systems requirements prior to proceeding with prototype development. The present status of the COTSS instrument is given and the areas in which system refinements are required, are defined.

  16. The adaptive synchronization of fractional-order Liu chaotic system ...

    Indian Academy of Sciences (India)

    In this paper, the chaos control and the synchronization of two fractional-order Liu chaotic systems with unknown parameters are studied. According to the Lyapunov stabilization theory and the adaptive control theorem, the adaptive control rule is obtained for the described error dynamic stabilization. Using the adaptive rule ...

  17. Fiber coupled optical spark delivery system

    Science.gov (United States)

    Yalin, Azer; Willson, Bryan; Defoort, Morgan

    2008-08-12

    A spark delivery system for generating a spark using a laser beam is provided, the spark delivery system including a laser light source and a laser delivery assembly. The laser delivery assembly includes a hollow fiber and a launch assembly comprising launch focusing optics to input the laser beam in the hollow fiber. In addition, the laser delivery assembly includes exit focusing optics that demagnify an exit beam of laser light from the hollow fiber, thereby increasing the intensity of the laser beam and creating a spark. In accordance with embodiments of the present invention, the assembly may be used to create a spark in a combustion engine. In accordance with other embodiments of the present invention, a method of using the spark delivery system is provided. In addition, a method of choosing an appropriate fiber for creating a spark using a laser beam is also presented.

  18. MEMS Deformable Mirrors for Adaptive Optics in Astronomical Imaging

    Science.gov (United States)

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

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

  19. Differential Polarization Nonlinear Optical Microscopy with Adaptive Optics Controlled Multiplexed Beams

    Directory of Open Access Journals (Sweden)

    Virginijus Barzda

    2013-09-01

    Full Text Available Differential polarization nonlinear optical microscopy has the potential to become an indispensable tool for structural investigations of ordered biological assemblies and microcrystalline aggregates. Their microscopic organization can be probed through fast and sensitive measurements of nonlinear optical signal anisotropy, which can be achieved with microscopic spatial resolution by using time-multiplexed pulsed laser beams with perpendicular polarization orientations and photon-counting detection electronics for signal demultiplexing. In addition, deformable membrane mirrors can be used to correct for optical aberrations in the microscope and simultaneously optimize beam overlap using a genetic algorithm. The beam overlap can be achieved with better accuracy than diffraction limited point-spread function, which allows to perform polarization-resolved measurements on the pixel-by-pixel basis. We describe a newly developed differential polarization microscope and present applications of the differential microscopy technique for structural studies of collagen and cellulose. Both, second harmonic generation, and fluorescence-detected nonlinear absorption anisotropy are used in these investigations. It is shown that the orientation and structural properties of the fibers in biological tissue can be deduced and that the orientation of fluorescent molecules (Congo Red, which label the fibers, can be determined. Differential polarization microscopy sidesteps common issues such as photobleaching and sample movement. Due to tens of megahertz alternating polarization of excitation pulses fast data acquisition can be conveniently applied to measure changes in the nonlinear signal anisotropy in dynamically changing in vivo structures.

  20. Differential polarization nonlinear optical microscopy with adaptive optics controlled multiplexed beams.

    Science.gov (United States)

    Samim, Masood; Sandkuijl, Daaf; Tretyakov, Ian; Cisek, Richard; Barzda, Virginijus

    2013-09-09

    Differential polarization nonlinear optical microscopy has the potential to become an indispensable tool for structural investigations of ordered biological assemblies and microcrystalline aggregates. Their microscopic organization can be probed through fast and sensitive measurements of nonlinear optical signal anisotropy, which can be achieved with microscopic spatial resolution by using time-multiplexed pulsed laser beams with perpendicular polarization orientations and photon-counting detection electronics for signal demultiplexing. In addition, deformable membrane mirrors can be used to correct for optical aberrations in the microscope and simultaneously optimize beam overlap using a genetic algorithm. The beam overlap can be achieved with better accuracy than diffraction limited point-spread function, which allows to perform polarization-resolved measurements on the pixel-by-pixel basis. We describe a newly developed differential polarization microscope and present applications of the differential microscopy technique for structural studies of collagen and cellulose. Both, second harmonic generation, and fluorescence-detected nonlinear absorption anisotropy are used in these investigations. It is shown that the orientation and structural properties of the fibers in biological tissue can be deduced and that the orientation of fluorescent molecules (Congo Red), which label the fibers, can be determined. Differential polarization microscopy sidesteps common issues such as photobleaching and sample movement. Due to tens of megahertz alternating polarization of excitation pulses fast data acquisition can be conveniently applied to measure changes in the nonlinear signal anisotropy in dynamically changing in vivo structures.