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Sample records for optical computers

  1. Optical computing.

    NASA Technical Reports Server (NTRS)

    Stroke, G. W.

    1972-01-01

    Applications of the optical computer include an approach for increasing the sharpness of images obtained from the most powerful electron microscopes and fingerprint/credit card identification. The information-handling capability of the various optical computing processes is very great. Modern synthetic-aperture radars scan upward of 100,000 resolvable elements per second. Fields which have assumed major importance on the basis of optical computing principles are optical image deblurring, coherent side-looking synthetic-aperture radar, and correlative pattern recognition. Some examples of the most dramatic image deblurring results are shown.

  2. Scalable optical quantum computer

    SciTech Connect

    Manykin, E A; Mel'nichenko, E V

    2014-12-31

    A way of designing a scalable optical quantum computer based on the photon echo effect is proposed. Individual rare earth ions Pr{sup 3+}, regularly located in the lattice of the orthosilicate (Y{sub 2}SiO{sub 5}) crystal, are suggested to be used as optical qubits. Operations with qubits are performed using coherent and incoherent laser pulses. The operation protocol includes both the method of measurement-based quantum computations and the technique of optical computations. Modern hybrid photon echo protocols, which provide a sufficient quantum efficiency when reading recorded states, are considered as most promising for quantum computations and communications. (quantum computer)

  3. Optical signal computing

    NASA Astrophysics Data System (ADS)

    Cathey, Wade Thomas; Schmidt, Rodney A.; Moddel, Garret

    1989-12-01

    Architectures for optical symbolic computing were designed, devices were designed and built that were specifically for the architectures, and test circuits for some of the logic elements were designed, constructed, and operated. The research elements were designed, constructed, and operated. The research led to novel architectures for optical symbolic computing. Devices were developed that are suitable for optical 2-D memory and logic. These devices are pixilated photo-addressed spatial light modulators (SLMs) with a three terminal arrangement so that the threshold can be adjusted. Spinoff non-pixilated devices are useful as high frame rate, high resolution SLMs that can be used for many optical signal processing applications.

  4. Optical Computing Research.

    DTIC Science & Technology

    1985-06-01

    D i No 24 15 December 1984 • . .A AD-A162 272 OPTICAL COMPUTING RESEARCH(U) STANFORD UNIV CA 2 / 2 INFORMATION SYSTEMS... 2 - .. reconstruction is quite general, independent of chemical d , processing and film type. Fig. 9. Generalized optical Fourier transform geometry...I I Bearn / Expander B n R2{ Laser Fig. 9. Optical system for recording A- ’. produces its Fourier transform, a 2 - D sinc function, on (a) the

  5. Optical computer motherboards

    NASA Astrophysics Data System (ADS)

    Jannson, Tomasz P.; Xu, Guoda; Bartha, John M.; Gruntman, Michael A.

    1997-09-01

    In this paper, we investigate the application of precision plastic optics into a communication/computer sub-system, such as a hybrid computer motherboard. We believe that using optical waveguides for next-generation computer motherboards can provide a high performance alternative for present multi-layer printed circuit motherboards. In response to this demand, we suggest our novel concept of a hybrid motherboard based on an internal-fiber-coupling (IFC) wavelength-division-multiplexing (WDM) optical backplane. The IFC/WDM backplane provides dedicated Tx/Rx connections, and applies low-cost, high-performance components, including CD LDs, GRIN plastic fibers, molding housing, and nonimaging optics connectors. Preliminary motherboard parameters are: speed 100 MHz/100 m, or 1 GHz/10 m; fiber loss approximately 0.01 dB/m; almost zero fan-out/fan-in optical power loss, and eight standard wavelength channels. The proposed hybrid computer motherboard, based on innovative optical backplane technology, should solve low-speed, low-parallelism bottlenecks in present electric computer motherboards.

  6. Optical quantum computing.

    PubMed

    O'Brien, Jeremy L

    2007-12-07

    In 2001, all-optical quantum computing became feasible with the discovery that scalable quantum computing is possible using only single-photon sources, linear optical elements, and single-photon detectors. Although it was in principle scalable, the massive resource overhead made the scheme practically daunting. However, several simplifications were followed by proof-of-principle demonstrations, and recent approaches based on cluster states or error encoding have dramatically reduced this worrying resource overhead, making an all-optical architecture a serious contender for the ultimate goal of a large-scale quantum computer. Key challenges will be the realization of high-efficiency sources of indistinguishable single photons, low-loss, scalable optical circuits, high-efficiency single-photon detectors, and low-loss interfacing of these components.

  7. Optical computer switching network

    NASA Technical Reports Server (NTRS)

    Clymer, B.; Collins, S. A., Jr.

    1985-01-01

    The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

  8. All-optical reservoir computing.

    PubMed

    Duport, François; Schneider, Bendix; Smerieri, Anteo; Haelterman, Marc; Massar, Serge

    2012-09-24

    Reservoir Computing is a novel computing paradigm that uses a nonlinear recurrent dynamical system to carry out information processing. Recent electronic and optoelectronic Reservoir Computers based on an architecture with a single nonlinear node and a delay loop have shown performance on standardized tasks comparable to state-of-the-art digital implementations. Here we report an all-optical implementation of a Reservoir Computer, made of off-the-shelf components for optical telecommunications. It uses the saturation of a semiconductor optical amplifier as nonlinearity. The present work shows that, within the Reservoir Computing paradigm, all-optical computing with state-of-the-art performance is possible.

  9. Optics in neural computation

    NASA Astrophysics Data System (ADS)

    Levene, Michael John

    In all attempts to emulate the considerable powers of the brain, one is struck by both its immense size, parallelism, and complexity. While the fields of neural networks, artificial intelligence, and neuromorphic engineering have all attempted oversimplifications on the considerable complexity, all three can benefit from the inherent scalability and parallelism of optics. This thesis looks at specific aspects of three modes in which optics, and particularly volume holography, can play a part in neural computation. First, holography serves as the basis of highly-parallel correlators, which are the foundation of optical neural networks. The huge input capability of optical neural networks make them most useful for image processing and image recognition and tracking. These tasks benefit from the shift invariance of optical correlators. In this thesis, I analyze the capacity of correlators, and then present several techniques for controlling the amount of shift invariance. Of particular interest is the Fresnel correlator, in which the hologram is displaced from the Fourier plane. In this case, the amount of shift invariance is limited not just by the thickness of the hologram, but by the distance of the hologram from the Fourier plane. Second, volume holography can provide the huge storage capacity and high speed, parallel read-out necessary to support large artificial intelligence systems. However, previous methods for storing data in volume holograms have relied on awkward beam-steering or on as-yet non- existent cheap, wide-bandwidth, tunable laser sources. This thesis presents a new technique, shift multiplexing, which is capable of very high densities, but which has the advantage of a very simple implementation. In shift multiplexing, the reference wave consists of a focused spot a few millimeters in front of the hologram. Multiplexing is achieved by simply translating the hologram a few tens of microns or less. This thesis describes the theory for how shift

  10. Optical Computers and Space Technology

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  11. Optical computing for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao; Huo, Tiancheng; Wang, Chengming; Liao, Wenchao; Chen, Tianyuan; Ai, Shengnan; Zhang, Wenxin; Hsieh, Jui-Cheng; Xue, Ping

    2016-11-01

    We propose an all-optical Fourier transformation system for real-time massive data processing in high speed optical coherence tomography (OCT). In the so-called optical computing OCT, fast Fourier transformation (FFT) of A-scan signal is optically processed in real time before being detected by photoelectric detector. Therefore, the processing time for interpolation and FFT in traditional Fourier domain OCT can be dramatically eliminated. A processing rate of 10 mega-A-scans/second was experimentally achieved, which is, to our knowledge, the highest speed for OCT imaging. Due to its fiber based all-optical configuration, this optical computing OCT system is ideal for ultrahigh speed volumetric OCT imaging in clinical application.

  12. Optical computing for optical coherence tomography

    PubMed Central

    Zhang, Xiao; Huo, Tiancheng; Wang, Chengming; Liao, Wenchao; Chen, Tianyuan; Ai, Shengnan; Zhang, Wenxin; Hsieh, Jui-Cheng; Xue, Ping

    2016-01-01

    We propose an all-optical Fourier transformation system for real-time massive data processing in high speed optical coherence tomography (OCT). In the so-called optical computing OCT, fast Fourier transformation (FFT) of A-scan signal is optically processed in real time before being detected by photoelectric detector. Therefore, the processing time for interpolation and FFT in traditional Fourier domain OCT can be dramatically eliminated. A processing rate of 10 mega-A-scans/second was experimentally achieved, which is, to our knowledge, the highest speed for OCT imaging. Due to its fiber based all-optical configuration, this optical computing OCT system is ideal for ultrahigh speed volumetric OCT imaging in clinical application. PMID:27869131

  13. Computer Generated Holographic Optics.

    DTIC Science & Technology

    1980-05-01

    with a conventional optical processor for synthetic aperture radar Imaging,these phase plates would allow for the compensation of several wavelengths...of phase error in the radar signal history. This task is current- ly very difficult to perform in a dynamic manner using conventional optics...R.C. Fairchild and J.R. Fienup Radar and Optics Division Environmental Research Institute of Michigan P.O. Box 8618, Ann Arbor, Michigan 48107 Abstract

  14. Computational Ion Optics Design Evaluations

    NASA Technical Reports Server (NTRS)

    Malone, Shane P.; Soulas, George C.

    2004-01-01

    Ion optics computational models are invaluable tools in the design of ion optics systems. In this study a new computational model developed by an outside vendor for use at the NASA Glenn Research Center (GRC) is presented. This computational model is a gun code that has been modified to model the plasma sheaths both upstream and downstream of the ion optics. The model handles multiple species (e.g. singly and doubly-charged ions) and includes a charge-exchange model to support erosion estimations. The model uses commercially developed solid design and meshing software to allow high flexibility in ion optics geometric configurations. The results from this computational model are applied to the NEXT project to investigate the effects of crossover impingement erosion seen during the 2000-hour wear test.

  15. Optical Computing Research.

    DTIC Science & Technology

    1987-10-30

    typically exists a multitude of integrated circuit chips, many of which must communicate with one another. The communication distances involved range from of...near a ground plane, and in, ced can be routed in a flexible manner through three - dimensional space. 4 A third advantage of optical interconnects...over an active integrated circuit, in which detectors and/or sources have been integrated . The problem of efficient coupling into and out of the

  16. Optics and Symbolic Computing

    DTIC Science & Technology

    1990-02-15

    efficiency of focusing on specific regions of an image for a specific purpose, such as resolving an edge and following a lineal feature. 5At other...I I I I PART II I TABLE OF CONTENTS Chapter Page I Program Philosophy 1 II Optical Relational Algebra Machines 9 III Pattern Matching in Symbolic...matrix algebra is most convenient for this set of problems and has the additional advantage of having been studied extensively over the past hundred

  17. Optical Computing Research.

    DTIC Science & Technology

    1983-03-31

    a length 2 input vector x, producing two single-mode optical fibres weakly coupled by a a length 2 output vector y. We can regard this series of fibre ...above the processors and are of varying intensities on the input fibre , while the assumed to arrive with a timing represented by output elements...accumulate as they propagate along their vertical distance above the processors. Any the output fibre and emerge in time sequence. If time interval

  18. Optical computing: introduction by the feature editors.

    PubMed

    Hinton, H S; Soffer, B; Tooley, F A; Yukimatsu, K

    1994-03-10

    This feature of Applied Optics: Information Processing on optical computing comprises thirty papers. Most of the papers evolved from papers presented at the Fifth Topical Meeting on Optical Computing held in March 1993 in Palm Springs, California.

  19. Electro-Optic Computing Architectures. Volume I

    DTIC Science & Technology

    1998-02-01

    The objective of the Electro - Optic Computing Architecture (EOCA) program was to develop multi-function electro - optic interfaces and optical...interconnect units to enhance the performance of parallel processor systems and form the building blocks for future electro - optic computing architectures...Specifically, three multi-function interface modules were targeted for development - an Electro - Optic Interface (EOI), an Optical Interconnection Unit (OW

  20. Research in Optical Symbolic Computing Tasks

    DTIC Science & Technology

    1988-05-31

    the Integration of Optical Computing , we have developed an adaptive neural network based algorithm for a fundamental problem in image processing, viz...IEEE International Conference on Neural Networks, San Diego, July 1988. 5. B.K. Jenkins and C.L. Giles, "Superposition in Optical Computing ...Angeles, California, 10-15 January, 1988. " Neural Network Models for Optical Computing ", SPIE vol. 882. • -# - - Where M(k) and l(k) are the input

  1. Digital optical computers at the optoelectronic computing systems center

    NASA Technical Reports Server (NTRS)

    Jordan, Harry F.

    1991-01-01

    The Digital Optical Computing Program within the National Science Foundation Engineering Research Center for Opto-electronic Computing Systems has as its specific goal research on optical computing architectures suitable for use at the highest possible speeds. The program can be targeted toward exploiting the time domain because other programs in the Center are pursuing research on parallel optical systems, exploiting optical interconnection and optical devices and materials. Using a general purpose computing architecture as the focus, we are developing design techniques, tools and architecture for operation at the speed of light limit. Experimental work is being done with the somewhat low speed components currently available but with architectures which will scale up in speed as faster devices are developed. The design algorithms and tools developed for a general purpose, stored program computer are being applied to other systems such as optimally controlled optical communication networks.

  2. The prospects of the digital optical computer

    NASA Astrophysics Data System (ADS)

    Bartelt, H.; Lohmann, A. W.; Weigelt, J.

    1985-03-01

    The suitability of electrons and photons for the purpose of computing is assessed. Based on these fundamental features it is pointed out why photons are in some ways better suited for parallel processors. Parallel processors are needed to satisfy the ever-increasing demand for speed of computation. The status of digital optical computing experiments is surveyed. It is concluded that electrons are well suited for switching operations as they occur in a logic processor. But electrons are not so easy to guide from one point to another point. On that score, photons are more suitable. Recently, photons became amenable also for logic processing. Hence, the stage is set for the development of an all-optical digital computer. A digital optical computer has as its assests: parallel processing; global interconnections, that are favorable for architecture and algorithms. But the digital optical computer is a late-comer. Nevertheless, the optical computer has a chance to supplement the electronic computer as a special purpose parallel processor.

  3. The Particle Beam Optics Interactive Computer Laboratory

    SciTech Connect

    Gillespie, G.H.; Hill, B.W.; Brown, N.A.; Babcock, R.C.; Martono, H.; Carey, D.C. |

    1997-02-01

    The Particle Beam Optics Interactive Computer Laboratory (PBO Lab) is an educational software concept to aid students and professionals in learning about charged particle beams and particle beam optical systems. The PBO Lab is being developed as a cross-platform application and includes four key elements. The first is a graphic user interface shell that provides for a highly interactive learning session. The second is a knowledge database containing information on electric and magnetic optics transport elements. The knowledge database provides interactive tutorials on the fundamental physics of charged particle optics and on the technology used in particle optics hardware. The third element is a graphical construction kit that provides tools for students to interactively and visually construct optical beamlines. The final element is a set of charged particle optics computational engines that compute trajectories, transport beam envelopes, fit parameters to optical constraints and carry out similar calculations for the student designed beamlines. The primary computational engine is provided by the third-order TRANSPORT code. Augmenting TRANSPORT is the multiple ray tracing program TURTLE and a first-order matrix program that includes a space charge model and support for calculating single particle trajectories in the presence of the beam space charge. This paper describes progress on the development of the PBO Lab. {copyright} {ital 1997 American Institute of Physics.}

  4. The Particle Beam Optics Interactive Computer Laboratory

    SciTech Connect

    Gillespie, George H.; Hill, Barrey W.; Brown, Nathan A.; Babcock, R. Chris; Martono, Hendy; Carey, David C.

    1997-02-01

    The Particle Beam Optics Interactive Computer Laboratory (PBO Lab) is an educational software concept to aid students and professionals in learning about charged particle beams and particle beam optical systems. The PBO Lab is being developed as a cross-platform application and includes four key elements. The first is a graphic user interface shell that provides for a highly interactive learning session. The second is a knowledge database containing information on electric and magnetic optics transport elements. The knowledge database provides interactive tutorials on the fundamental physics of charged particle optics and on the technology used in particle optics hardware. The third element is a graphical construction kit that provides tools for students to interactively and visually construct optical beamlines. The final element is a set of charged particle optics computational engines that compute trajectories, transport beam envelopes, fit parameters to optical constraints and carry out similar calculations for the student designed beamlines. The primary computational engine is provided by the third-order TRANSPORT code. Augmenting TRANSPORT is the multiple ray tracing program TURTLE and a first-order matrix program that includes a space charge model and support for calculating single particle trajectories in the presence of the beam space charge. This paper describes progress on the development of the PBO Lab.

  5. Nonlinear optics quantum computing with circuit QED.

    PubMed

    Adhikari, Prabin; Hafezi, Mohammad; Taylor, J M

    2013-02-08

    One approach to quantum information processing is to use photons as quantum bits and rely on linear optical elements for most operations. However, some optical nonlinearity is necessary to enable universal quantum computing. Here, we suggest a circuit-QED approach to nonlinear optics quantum computing in the microwave regime, including a deterministic two-photon phase gate. Our specific example uses a hybrid quantum system comprising a LC resonator coupled to a superconducting flux qubit to implement a nonlinear coupling. Compared to the self-Kerr nonlinearity, we find that our approach has improved tolerance to noise in the qubit while maintaining fast operation.

  6. Quantum computation architecture using optical tweezers

    SciTech Connect

    Weitenberg, Christof; Kuhr, Stefan; Moelmer, Klaus; Sherson, Jacob F.

    2011-09-15

    We present a complete architecture for scalable quantum computation with ultracold atoms in optical lattices using optical tweezers focused to the size of a lattice spacing. We discuss three different two-qubit gates based on local collisional interactions. The gates between arbitrary qubits require the transport of atoms to neighboring sites. We numerically optimize the nonadiabatic transport of the atoms through the lattice and the intensity ramps of the optical tweezer in order to maximize the gate fidelities. We find overall gate times of a few 100 {mu}s, while keeping the error probability due to vibrational excitations and spontaneous scattering below 10{sup -3}. The requirements on the positioning error and intensity noise of the optical tweezer and the magnetic field stability are analyzed and we show that atoms in optical lattices could meet the requirements for fault-tolerant scalable quantum computing.

  7. Optically intraconnected computer employing dynamically reconfigurable holographic optical element

    NASA Technical Reports Server (NTRS)

    Bergman, Larry A. (Inventor)

    1992-01-01

    An optically intraconnected computer and a reconfigurable holographic optical element employed therein. The basic computer comprises a memory for holding a sequence of instructions to be executed; logic for accessing the instructions in sequence; logic for determining for each the instruction the function to be performed and the effective address thereof; a plurality of individual elements on a common support substrate optimized to perform certain logical sequences employed in executing the instructions; and, element selection logic connected to the logic determining the function to be performed for each the instruction for determining the class of each function and for causing the instruction to be executed by those the elements which perform those associated the logical sequences affecting the instruction execution in an optimum manner. In the optically intraconnected version, the element selection logic is adapted for transmitting and switching signals to the elements optically.

  8. Center for the Integration of Optical Computing

    DTIC Science & Technology

    1993-10-15

    completed, the largest gains in III-V semiconductors, which we achieved in GaAs, required moving gratings, a difficult-to-achieve technology in which a...wavelength-division-multiplexing (WDM). However, transmitting many WDM amplified channels is difficult to implement since the EDFA gain is wavelength...optical computing system due to the EDFA’s non-uniform gain . I1) Passive equalization of non-uniform EDFA gain by optical filtering for transmission

  9. Computational cameras: convergence of optics and processing.

    PubMed

    Zhou, Changyin; Nayar, Shree K

    2011-12-01

    A computational camera uses a combination of optics and processing to produce images that cannot be captured with traditional cameras. In the last decade, computational imaging has emerged as a vibrant field of research. A wide variety of computational cameras has been demonstrated to encode more useful visual information in the captured images, as compared with conventional cameras. In this paper, we survey computational cameras from two perspectives. First, we present a taxonomy of computational camera designs according to the coding approaches, including object side coding, pupil plane coding, sensor side coding, illumination coding, camera arrays and clusters, and unconventional imaging systems. Second, we use the abstract notion of light field representation as a general tool to describe computational camera designs, where each camera can be formulated as a projection of a high-dimensional light field to a 2-D image sensor. We show how individual optical devices transform light fields and use these transforms to illustrate how different computational camera designs (collections of optical devices) capture and encode useful visual information.

  10. Optical Computing Based on Neuronal Models

    DTIC Science & Technology

    1988-05-01

    walking, and cognition are far too complex for existing sequential digital computers. Therefore new architectures, hardware, and algorithms modeled...collective behavior, and iterative processing into optical processing and artificial neurodynamical systems. Another intriguing promise of neural nets is...with architectures, implementations, and programming; and material research s -7- called for. Our future research in neurodynamics will continue to

  11. Multivariate optical computation for predictive spectroscopy.

    PubMed

    Nelson, M P; Aust, J F; Dobrowolski, J A; Verly, P G; Myrick, M L

    1998-01-01

    A novel optical approach to predicting chemical and physical properties based on principal component analysis (PCA) is proposed and evaluated using a data set from earlier work. In our approach, a regression vector produced by PCA is designed into the structure of a set of paired optical filters. Light passing through the paired filters produces an analog detector signal that is directly proportional to the chemical/physical property for which the regression vector was designed. This simple optical computational method for predictive spectroscopy is evaluated in several ways, using the example data for numeric simulation. First, we evaluate the sensitivity of the method to various types of spectroscopic errors commonly encountered and find the method to have the same susceptibilities toward error as standard methods. Second, we use propagation of errors to determine the effects of detector noise on the predictive power of the method, finding the optical computation approach to have a large multiplex advantage over conventional methods. Third, we use two different design approaches to the construction of the paired filter set for the example measurement to evaluate manufacturability, finding that adequate methods exist to design appropriate optical devices. Fourth, we numerically simulate the predictive errors introduced by design errors in the paired filters, finding that predictive errors are not increased over conventional methods. Fifth, we consider how the performance of the method is affected by light intensities that are not linearly related to chemical composition (as in transmission spectroscopy) and find that the method is only marginally affected. In summary, we conclude that many types of predictive measurements based on use of regression (or other) vectors and linear mathematics can be performed more rapidly, more effectly, and at considerably lower cost by the proposed optical computation method than by traditional dispersive or interferometric

  12. Computer Modeling for Optical Waveguide Sensors.

    DTIC Science & Technology

    1987-12-15

    COSATI CODES 18 SUBJECT TERMS (Continue on reverse it necessary and cleritify by DIock numnerl FIEL GRUP SB-GOUP Optical waveguide sensors Computer...reflection. The resultant probe beam transmission may be plotted as a function of changes in the refractive index of the surrounding fluid medium. BASIC...all angles of incidence about the critical angle ecr. It should be noted that N in equation (3) is a function of e, since = sin - l sin 8 , see

  13. Computational algorithms for simulations in atmospheric optics.

    PubMed

    Konyaev, P A; Lukin, V P

    2016-04-20

    A computer simulation technique for atmospheric and adaptive optics based on parallel programing is discussed. A parallel propagation algorithm is designed and a modified spectral-phase method for computer generation of 2D time-variant random fields is developed. Temporal power spectra of Laguerre-Gaussian beam fluctuations are considered as an example to illustrate the applications discussed. Implementation of the proposed algorithms using Intel MKL and IPP libraries and NVIDIA CUDA technology is shown to be very fast and accurate. The hardware system for the computer simulation is an off-the-shelf desktop with an Intel Core i7-4790K CPU operating at a turbo-speed frequency up to 5 GHz and an NVIDIA GeForce GTX-960 graphics accelerator with 1024 1.5 GHz processors.

  14. Variational optical flow computation in real time.

    PubMed

    Bruhn, Andrés; Weickert, Joachim; Feddern, Christian; Kohlberger, Timo; Schnörr, Christoph

    2005-05-01

    This paper investigates the usefulness of bidirectional multigrid methods for variational optical flow computations. Although these numerical schemes are among the fastest methods for solving equation systems, they are rarely applied in the field of computer vision. We demonstrate how to employ those numerical methods for the treatment of variational optical flow formulations and show that the efficiency of this approach even allows for real-time performance on standard PCs. As a representative for variational optic flow methods, we consider the recently introduced combined local-global method. It can be considered as a noise-robust generalization of the Horn and Schunck technique. We present a decoupled, as well as a coupled, version of the classical Gauss-Seidel solver, and we develop several multgrid implementations based on a discretization coarse grid approximation. In contrast, with standard bidirectional multigrid algorithms, we take advantage of intergrid transfer operators that allow for nondyadic grid hierarchies. As a consequence, no restrictions concerning the image size or the number of traversed levels have to be imposed. In the experimental section, we juxtapose the developed multigrid schemes and demonstrate their superior performance when compared to unidirectional multgrid methods and nonhierachical solvers. For the well-known 316 x 252 Yosemite sequence, we succeeded in computing the complete set of dense flow fields in three quarters of a second on a 3.06-GHz Pentium4 PC. This corresponds to a frame rate of 18 flow fields per second which outperforms the widely-used Gauss-Seidel method by almost three orders of magnitude.

  15. A computer program to evaluate optical systems

    NASA Technical Reports Server (NTRS)

    Innes, D.

    1972-01-01

    A computer program is used to evaluate a 25.4 cm X-ray telescope at a field angle of 20 minutes of arc by geometrical analysis. The object is regarded as a point source of electromagnetic radiation, and the optical surfaces are treated as boundary conditions in the solution of the electromagnetic wave propagation equation. The electric field distribution is then determined in the region of the image and the intensity distribution inferred. A comparison of wave analysis results and photographs taken through the telescope shows excellent agreement.

  16. Optical high-performance computing: introduction to the JOSA A and Applied Optics feature.

    PubMed

    Caulfield, H John; Dolev, Shlomi; Green, William M J

    2009-08-01

    The feature issues in both Applied Optics and the Journal of the Optical Society of America A focus on topics of immediate relevance to the community working in the area of optical high-performance computing.

  17. Parallel reservoir computing using optical amplifiers.

    PubMed

    Vandoorne, Kristof; Dambre, Joni; Verstraeten, David; Schrauwen, Benjamin; Bienstman, Peter

    2011-09-01

    Reservoir computing (RC), a computational paradigm inspired on neural systems, has become increasingly popular in recent years for solving a variety of complex recognition and classification problems. Thus far, most implementations have been software-based, limiting their speed and power efficiency. Integrated photonics offers the potential for a fast, power efficient and massively parallel hardware implementation. We have previously proposed a network of coupled semiconductor optical amplifiers as an interesting test case for such a hardware implementation. In this paper, we investigate the important design parameters and the consequences of process variations through simulations. We use an isolated word recognition task with babble noise to evaluate the performance of the photonic reservoirs with respect to traditional software reservoir implementations, which are based on leaky hyperbolic tangent functions. Our results show that the use of coherent light in a well-tuned reservoir architecture offers significant performance benefits. The most important design parameters are the delay and the phase shift in the system's physical connections. With optimized values for these parameters, coherent semiconductor optical amplifier (SOA) reservoirs can achieve better results than traditional simulated reservoirs. We also show that process variations hardly degrade the performance, but amplifier noise can be detrimental. This effect must therefore be taken into account when designing SOA-based RC implementations.

  18. Computing Temperatures in Optically Thick Protoplanetary Disks

    NASA Technical Reports Server (NTRS)

    Capuder, Lawrence F.. Jr.

    2011-01-01

    We worked with a Monte Carlo radiative transfer code to simulate the transfer of energy through protoplanetary disks, where planet formation occurs. The code tracks photons from the star into the disk, through scattering, absorption and re-emission, until they escape to infinity. High optical depths in the disk interior dominate the computation time because it takes the photon packet many interactions to get out of the region. High optical depths also receive few photons and therefore do not have well-estimated temperatures. We applied a modified random walk (MRW) approximation for treating high optical depths and to speed up the Monte Carlo calculations. The MRW is implemented by calculating the average number of interactions the photon packet will undergo in diffusing within a single cell of the spatial grid and then updating the packet position, packet frequencies, and local radiation absorption rate appropriately. The MRW approximation was then tested for accuracy and speed compared to the original code. We determined that MRW provides accurate answers to Monte Carlo Radiative transfer simulations. The speed gained from using MRW is shown to be proportional to the disk mass.

  19. Computational methods for optical molecular imaging

    PubMed Central

    Chen, Duan; Wei, Guo-Wei; Cong, Wen-Xiang; Wang, Ge

    2010-01-01

    Summary A new computational technique, the matched interface and boundary (MIB) method, is presented to model the photon propagation in biological tissue for the optical molecular imaging. Optical properties have significant differences in different organs of small animals, resulting in discontinuous coefficients in the diffusion equation model. Complex organ shape of small animal induces singularities of the geometric model as well. The MIB method is designed as a dimension splitting approach to decompose a multidimensional interface problem into one-dimensional ones. The methodology simplifies the topological relation near an interface and is able to handle discontinuous coefficients and complex interfaces with geometric singularities. In the present MIB method, both the interface jump condition and the photon flux jump conditions are rigorously enforced at the interface location by using only the lowest-order jump conditions. This solution near the interface is smoothly extended across the interface so that central finite difference schemes can be employed without the loss of accuracy. A wide range of numerical experiments are carried out to validate the proposed MIB method. The second-order convergence is maintained in all benchmark problems. The fourth-order convergence is also demonstrated for some three-dimensional problems. The robustness of the proposed method over the variable strength of the linear term of the diffusion equation is also examined. The performance of the present approach is compared with that of the standard finite element method. The numerical study indicates that the proposed method is a potentially efficient and robust approach for the optical molecular imaging. PMID:20485461

  20. Hybrid (Optical/Electronic) Computing and Digital Computing

    DTIC Science & Technology

    1988-06-01

    n ............................................................................................................................ 3 2 . Hybrid ( Optical ...implementation of architectures of fully and hypercube interconnection topology. ’S. 2 . 11 brid ( Optical -Analog/’Electronic Mlicro-) Comiputer 2.1. Optical ...variant optical /electronic processor of Fig. 2 to detect the three parameters of a circle and the four parameters of an ellipse; the experimental

  1. NMR quantum computation with optically polarized molecules

    NASA Astrophysics Data System (ADS)

    Verhulst, Anne; Yannoni, Constantino; Sherwood, Mark; Pomerantz, Drew; Vandersypen, Lieven; Chuang, Isaac

    2000-03-01

    Current methods for bulk NMR quantum computation rely on nuclear spin polarization present at high temperature equilibrium. This presents a challenging obstacle as the probability to find a spin in a specific state decreases exponentially in the number of spins used as qubits, causing a corresponding decrease in the signal to noise ratio of the desired NMR signal. One way to address this problem is to provide an artificial source of high polarization, such as optically pumped ^129Xe. For comparison, thermal equilibrium polarizations are only about 10-3% for ^1H in a typical NMR experiment at room temperature and in a 10 Tesla magnetic field, but with ^129Xe polarizations as high as 18% have been achieved [Happer et. al., Chem.Phys.Lett., 284, p.87-92, Feb 1998]. Using this technique, we prepare hyperpolarized liquid Xe and use it as a solvent for chloroform molecules (CHCl_3). Cross polarization (SPINOE) between ^129Xe and ^1H results in measured enhancements of the proton signal of over 300%, and evidence of transfer to ^13C. These results provide hope for the scalability of quantum computation.

  2. Physical Optics Based Computational Imaging Systems

    NASA Astrophysics Data System (ADS)

    Olivas, Stephen Joseph

    There is an ongoing demand on behalf of the consumer, medical and military industries to make lighter weight, higher resolution, wider field-of-view and extended depth-of-focus cameras. This leads to design trade-offs between performance and cost, be it size, weight, power, or expense. This has brought attention to finding new ways to extend the design space while adhering to cost constraints. Extending the functionality of an imager in order to achieve extraordinary performance is a common theme of computational imaging, a field of study which uses additional hardware along with tailored algorithms to formulate and solve inverse problems in imaging. This dissertation details four specific systems within this emerging field: a Fiber Bundle Relayed Imaging System, an Extended Depth-of-Focus Imaging System, a Platform Motion Blur Image Restoration System, and a Compressive Imaging System. The Fiber Bundle Relayed Imaging System is part of a larger project, where the work presented in this thesis was to use image processing techniques to mitigate problems inherent to fiber bundle image relay and then, form high-resolution wide field-of-view panoramas captured from multiple sensors within a custom state-of-the-art imager. The Extended Depth-of-Focus System goals were to characterize the angular and depth dependence of the PSF of a focal swept imager in order to increase the acceptably focused imaged scene depth. The goal of the Platform Motion Blur Image Restoration System was to build a system that can capture a high signal-to-noise ratio (SNR), long-exposure image which is inherently blurred while at the same time capturing motion data using additional optical sensors in order to deblur the degraded images. Lastly, the objective of the Compressive Imager was to design and build a system functionally similar to the Single Pixel Camera and use it to test new sampling methods for image generation and to characterize it against a traditional camera. These computational

  3. Computer optics and photonics for students of laser engineering disciplines

    NASA Astrophysics Data System (ADS)

    Zakharov, V. P.

    2005-10-01

    The concept of teaching in optics and photonics for undergraduate and post-graduate students of laser engineering disciplines are discussed. The designed curriculum include as fundamental knowledge on modern mathematics, physics and computer methods as up-to-date industrial optical engineering software training. Distributed Web-server technology with Alpha cluster station background allow to support real-time training and teaching with a set of computer optical laboratories, which are used as a framework for most university special courses. Remote access to facilities of Russian Academy of Science make it possible to accumulate modern science achievements in optical education.

  4. Implementations of adaptive associative optical computing elements

    NASA Astrophysics Data System (ADS)

    Fisher, Arthur D.; Lee, John N.; Fukuda, Robert C.

    1986-01-01

    The present optical implementations for heteroassociative memory modules, which are capable of real time adaptive learning, are pertinent to the eventual construction of large, multimodule associative/neural network architectures that can consider problems in the acquisition, transformation, matching/recognition, and manipulation of large amounts of data in parallel. These modules offer such performance features as convergence to the least-squares-optimum pseudoinverse association, accumulative and gated learning, forgetfulness of unused associations, resistance to dynamic-range saturation, and compensation of optical system aberrations. Optics uniquely furnish the massive parallel interconnection paths required to cascade and interconnect a number of modules to form the more sophisticated multiple module architectures.

  5. Encoded diffractive optics for full-spectrum computational imaging

    NASA Astrophysics Data System (ADS)

    Heide, Felix; Fu, Qiang; Peng, Yifan; Heidrich, Wolfgang

    2016-09-01

    Diffractive optical elements can be realized as ultra-thin plates that offer significantly reduced footprint and weight compared to refractive elements. However, such elements introduce severe chromatic aberrations and are not variable, unless used in combination with other elements in a larger, reconfigurable optical system. We introduce numerically optimized encoded phase masks in which different optical parameters such as focus or zoom can be accessed through changes in the mechanical alignment of a ultra-thin stack of two or more masks. Our encoded diffractive designs are combined with a new computational approach for self-calibrating imaging (blind deconvolution) that can restore high-quality images several orders of magnitude faster than the state of the art without pre-calibration of the optical system. This co-design of optics and computation enables tunable, full-spectrum imaging using thin diffractive optics.

  6. Encoded diffractive optics for full-spectrum computational imaging

    PubMed Central

    Heide, Felix; Fu, Qiang; Peng, Yifan; Heidrich, Wolfgang

    2016-01-01

    Diffractive optical elements can be realized as ultra-thin plates that offer significantly reduced footprint and weight compared to refractive elements. However, such elements introduce severe chromatic aberrations and are not variable, unless used in combination with other elements in a larger, reconfigurable optical system. We introduce numerically optimized encoded phase masks in which different optical parameters such as focus or zoom can be accessed through changes in the mechanical alignment of a ultra-thin stack of two or more masks. Our encoded diffractive designs are combined with a new computational approach for self-calibrating imaging (blind deconvolution) that can restore high-quality images several orders of magnitude faster than the state of the art without pre-calibration of the optical system. This co-design of optics and computation enables tunable, full-spectrum imaging using thin diffractive optics. PMID:27633055

  7. One-way quantum computing in the optical frequency comb.

    PubMed

    Menicucci, Nicolas C; Flammia, Steven T; Pfister, Olivier

    2008-09-26

    One-way quantum computing allows any quantum algorithm to be implemented easily using just measurements. The difficult part is creating the universal resource, a cluster state, on which the measurements are made. We propose a scalable method that uses a single, multimode optical parametric oscillator (OPO). The method is very efficient and generates a continuous-variable cluster state, universal for quantum computation, with quantum information encoded in the quadratures of the optical frequency comb of the OPO.

  8. Computed tomographic identification of calcified optic nerve drusen

    SciTech Connect

    Ramirez, H.; Blatt, E.S.; Hibri, N.S.

    1983-07-01

    Four cases of optic disk drusen were accurately diagnosed with orbital computed tomography (CT). The radiologist should be aware of the characteristic CT finding of discrete calcification within an otherwise normal optic disk. This benign process is easily differentiated from lesions such as calcific neoplastic processes of the posterior globe. CT identification of optic disk drusen is essential in the evaluation of visual field defects, migraine-like headaches, and pseudopapilledema.

  9. Applied study of optical interconnection link in computer cluster

    NASA Astrophysics Data System (ADS)

    Zhou, Ge; Tian, Jindong; Zhang, Nan; Jing, Wencai; Li, Haifeng

    2000-10-01

    In this paper, some study results to apply fiber link to a computer cluster are presented. The research is based on a ring network topology for a cluster system, which is connected by gigabit/s virtual parallel optical fiber link (VPOFLink) and its driver is for Linux Operating System, the transmission protocol of VPOFLink is compliant with Ethernet standard. We have studied the effect of different types of motherboard on transmission rate of the VPOFLink, and have analyzed the influence of optical interconnection network topology and computer networks protocol on the performance of this optical interconnection computer cluster. The round-trip transmission bandwidth of the VPOFLink have been tested, and the factors that limit transmission bandwidth, such as modes of forwarding data packets in the optical interconnection ring networks, and the size of the link buffer etc., are investigated.

  10. All-optical reservoir computer based on saturation of absorption.

    PubMed

    Dejonckheere, Antoine; Duport, François; Smerieri, Anteo; Fang, Li; Oudar, Jean-Louis; Haelterman, Marc; Massar, Serge

    2014-05-05

    Reservoir computing is a new bio-inspired computation paradigm. It exploits a dynamical system driven by a time-dependent input to carry out computation. For efficient information processing, only a few parameters of the reservoir needs to be tuned, which makes it a promising framework for hardware implementation. Recently, electronic, opto-electronic and all-optical experimental reservoir computers were reported. In those implementations, the nonlinear response of the reservoir is provided by active devices such as optoelectronic modulators or optical amplifiers. By contrast, we propose here the first reservoir computer based on a fully passive nonlinearity, namely the saturable absorption of a semiconductor mirror. Our experimental setup constitutes an important step towards the development of ultrafast low-consumption analog computers.

  11. High Performance Seed Based Optical Computing.

    DTIC Science & Technology

    1998-05-01

    fibers in ’ retroreflector systems’ [42]. Circular VCSELs have arbitrary polarization, thus tend to preclude the use of polarization components, and...doped silica deposited by hollow cathode PECVD’, Electron. Lett.. 1996, 32, pp. 1198-1199 6 LOVE, J.D.: ’Application of low-loss criterion to optical

  12. Experimental Implementation of Efficient Linear Optics Quantum Computation

    DTIC Science & Technology

    2007-11-02

    Experimental Implementation of Efficient Linear Optics Quantum Computation Final Report G. J. Milburn, T. C. Ralph, and A. G. White University of...Queensland, Australia 1. Statement of Problem. One of the earliest proposals [1] for implementing quantum computation was based on encoding...containing few photons. In 2001 Knill, Laflamme and Milburn (KLM) found a way to circumvent this restriction and implement efficient quantum computation

  13. Recent Advances in Photonic Devices for Optical Computing and the Role of Nonlinear Optics-Part II

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin; Frazier, Donald O.; Witherow, William K.; Banks, Curtis E.; Paley, Mark S.

    2007-01-01

    The twentieth century has been the era of semiconductor materials and electronic technology while this millennium is expected to be the age of photonic materials and all-optical technology. Optical technology has led to countless optical devices that have become indispensable in our daily lives in storage area networks, parallel processing, optical switches, all-optical data networks, holographic storage devices, and biometric devices at airports. This chapters intends to bring some awareness to the state-of-the-art of optical technologies, which have potential for optical computing and demonstrate the role of nonlinear optics in many of these components. Our intent, in this Chapter, is to present an overview of the current status of optical computing, and a brief evaluation of the recent advances and performance of the following key components necessary to build an optical computing system: all-optical logic gates, adders, optical processors, optical storage, holographic storage, optical interconnects, spatial light modulators and optical materials.

  14. Fermionic Optical Lattices: A Computational Study

    DTIC Science & Technology

    2014-10-22

    Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 optical lattices, degenerate quantum gases , quantum control, correlation...with a different wavelength. We systematically determine the real - and momentum-space properties of these states. The crossover from 3D to two...fermions in square lattices. The phases are systematically characterized by the symmetry of the order parameter and the real - and momentum-space

  15. Photorefractive Tungsten Bronze Crystals for Optical Computing

    DTIC Science & Technology

    1993-07-23

    Science Center SC71041.FR temperature, larger crystals crack on cooling through these phase transitions. Our recent work on SCNN indicates that the...addition of Ba 2 + reduces the cracking of crystals while maintaining reasonably high electro- optic coefficients. We plan to continue BSCNN growth in...are tetragonal at room temperature, cracking of large crystals during cool-down through the ferroelectric phase transition is generally not a problem

  16. Electro-Optic Computing Architectures: Volume II. Components and System Design and Analysis

    DTIC Science & Technology

    1998-02-01

    The objective of the Electro - Optic Computing Architecture (EOCA) program was to develop multi-function electro - optic interfaces and optical...interconnect units to enhance the performance of parallel processor systems and form the building blocks for future electro - optic computing architectures...Specifically, three multi-function interface modules were targeted for development - an Electro - Optic Interface (EOI), an Optical Interconnection Unit

  17. Photodeposited diffractive optical elements of computer generated masks

    NASA Astrophysics Data System (ADS)

    Mirchin, N.; Peled, A.; Baal-Zedaka, I.; Margolin, R.; Zagon, M.; Lapsker, I.; Verdyan, A.; Azoulay, J.

    2005-07-01

    Diffractive optical elements (DOE) were synthesized on plastic substrates using the photodeposition (PD) technique by depositing amorphous selenium (a-Se) films with argon lasers and UV spectra light. The thin films were deposited typically onto polymethylmethacrylate (PMMA) substrates at room temperature. Scanned beam and contact mask modes were employed using computer-designed DOE lenses. Optical and electron micrographs characterize the surface details. The films were typically 200 nm thick.

  18. Single Photon Holographic Qudit Elements for Linear Optical Quantum Computing

    DTIC Science & Technology

    2011-05-01

    in optical volume holography and designed and simulated practical single-photon, single-optical elements for qudit MUB-state quantum in- formation...Independent of the representation we use, the MUB states will ordinarily be modulated in both amplitude and phase. Recently a practical method has been...quantum computing with qudits (d ≥ 3) has been an efficient and practical quantum state sorter for photons whose complex fields are modulated in both

  19. Optical processing for future computer networks

    NASA Technical Reports Server (NTRS)

    Husain, A.; Haugen, P. R.; Hutcheson, L. D.; Warrior, J.; Murray, N.; Beatty, M.

    1986-01-01

    In the development of future data management systems, such as the NASA Space Station, a major problem represents the design and implementation of a high performance communication network which is self-correcting and repairing, flexible, and evolvable. To obtain the goal of designing such a network, it will be essential to incorporate distributed adaptive network control techniques. The present paper provides an outline of the functional and communication network requirements for the Space Station data management system. Attention is given to the mathematical representation of the operations being carried out to provide the required functionality at each layer of communication protocol on the model. The possible implementation of specific communication functions in optics is also considered.

  20. Computational imaging using lightweight diffractive-refractive optics.

    PubMed

    Peng, Yifan; Fu, Qiang; Amata, Hadi; Su, Shuochen; Heide, Felix; Heidrich, Wolfgang

    2015-11-30

    Diffractive optical elements (DOE) show great promise for imaging optics that are thinner and more lightweight than conventional refractive lenses while preserving their light efficiency. Unfortunately, severe spectral dispersion currently limits the use of DOEs in consumer-level lens design. In this article, we jointly design lightweight diffractive-refractive optics and post-processing algorithms to enable imaging under white light illumination. Using the Fresnel lens as a general platform, we show three phase-plate designs, including a super-thin stacked plate design, a diffractive-refractive-hybrid lens, and a phase coded-aperture lens. Combined with cross-channel deconvolution algorithm, both spherical and chromatic aberrations are corrected. Experimental results indicate that using our computational imaging approach, diffractive-refractive optics is an alternative candidate to build light efficient and thin optics for white light imaging.

  1. Computer-aided detection of polyps in optical colonoscopy images

    NASA Astrophysics Data System (ADS)

    Nadeem, Saad; Kaufman, Arie

    2016-03-01

    We present a computer-aided detection algorithm for polyps in optical colonoscopy images. Polyps are the precursors to colon cancer. In the US alone, 14 million optical colonoscopies are performed every year, mostly to screen for polyps. Optical colonoscopy has been shown to have an approximately 25% polyp miss rate due to the convoluted folds and bends present in the colon. In this work, we present an automatic detection algorithm to detect these polyps in the optical colonoscopy images. We use a machine learning algorithm to infer a depth map for a given optical colonoscopy image and then use a detailed pre-built polyp profile to detect and delineate the boundaries of polyps in this given image. We have achieved the best recall of 84.0% and the best specificity value of 83.4%.

  2. Computational methods to compute wavefront error due to aero-optic effects

    NASA Astrophysics Data System (ADS)

    Genberg, Victor; Michels, Gregory; Doyle, Keith; Bury, Mark; Sebastian, Thomas

    2013-09-01

    Aero-optic effects can have deleterious effects on high performance airborne optical sensors that must view through turbulent flow fields created by the aerodynamic effects of windows and domes. Evaluating aero-optic effects early in the program during the design stages allows mitigation strategies and optical system design trades to be performed to optimize system performance. This necessitates a computationally efficient means to evaluate the impact of aero-optic effects such that the resulting dynamic pointing errors and wavefront distortions due to the spatially and temporally varying flow field can be minimized or corrected. To this end, an aero-optic analysis capability was developed within the commercial software SigFit that couples CFD results with optical design tools. SigFit reads the CFD generated density profile using the CGNS file format. OPD maps are then created by converting the three-dimensional density field into an index of refraction field and then integrating along specified paths to compute OPD errors across the optical field. The OPD maps may be evaluated directly against system requirements or imported into commercial optical design software including Zemax® and Code V® for a more detailed assessment of the impact on optical performance from which design trades may be performed.

  3. RADIAL COMPUTED TOMOGRAPHY OF AIR CONTAMINANTS USING OPTICAL REMOTE SENSING

    EPA Science Inventory

    The paper describes the application of an optical remote-sensing (ORS) system to map air contaminants and locate fugitive emissions. Many ORD systems may utilize radial non-overlapping beam geometry and a computed tomography (CT) algorithm to map the concentrations in a plane. In...

  4. High energy charged particle optics computer programs

    SciTech Connect

    Carey, D.C.

    1980-09-01

    The computer programs TRANSPORT and TURTLE are described, with special emphasis on recent developments. TRANSPORT is a general matrix evaluation and fitting program. First and second-order transfer matrix elements, including those contributing to time-of-flight differences can be evaluated. Matrix elements of both orders can be fit, separately or simultaneously. Floor coordinates of the beam line may be calculated and included in any fits. Tables of results of misalignments, including effects of bilinear terms can be produced. Fringe fields and pole face rotation angles of bending magnets may be included and also adjusted automatically during the fitting process to produce rectangular magnets. A great variety of output options are available. TURTLE is a Monte Carlo program used to simulate beam line performance. It includes second-order terms and aperture constraints. Replacable subroutines allow an unliminated variety of input beam distributions, scattering algorithms, variables which can be histogrammed, and aperture shapes. Histograms of beam loss can also be produced. Rectangular zero-gradient bending magnets with proper circular trajectories, sagitta offsets, pole face rotation angles, and aperture constraints can be included. The effect of multiple components of quadrupoles up to 40 poles can be evaluated.

  5. Toward optical signal processing using photonic reservoir computing.

    PubMed

    Vandoorne, Kristof; Dierckx, Wouter; Schrauwen, Benjamin; Verstraeten, David; Baets, Roel; Bienstman, Peter; Van Campenhout, Jan

    2008-07-21

    We propose photonic reservoir computing as a new approach to optical signal processing in the context of large scale pattern recognition problems. Photonic reservoir computing is a photonic implementation of the recently proposed reservoir computing concept, where the dynamics of a network of nonlinear elements are exploited to perform general signal processing tasks. In our proposed photonic implementation, we employ a network of coupled Semiconductor Optical Amplifiers (SOA) as the basic building blocks for the reservoir. Although they differ in many key respects from traditional software-based hyperbolic tangent reservoirs, we show using simulations that such a photonic reservoir can outperform traditional reservoirs on a benchmark classification task. Moreover, a photonic implementation offers the promise of massively parallel information processing with low power and high speed.

  6. Single Element 2-DIMENSIONAL Acousto-Optic Deflectors Design, Fabrication and Implementation for Digital Optical Computing

    NASA Astrophysics Data System (ADS)

    Rosemeier, Jolanta Iwona

    1992-09-01

    With the need to develop very fast computers compared to the conventional digital chip based systems, the future is very bright for optical based signal processing. Attention has turned to a different application of optics utilizing mathematical operations, in which case operations are numerical, sometimes discrete, and often algebraic in nature. Interest has been so vigorous that many view it as a small revolution in optics whereby optical signal processing is beginning to encompass what many frequently describe as optical computing. The term is fully intended to imply close comparison with the operations performed by scientific digital computers. Most present computer intensive problem solving processors rely on a common set of linear equations found in numerical matrix algebra. Recently, considerable research focused on the use of systolic array, which can operate at high speeds with great efficiency. This approach addresses the acousto-optic digital and analog arrays utilizing three dimensional optical interconnect technology. In part I of this dissertation the first single element 2-dimensional (2-D) acousto-optic deflector was designed, fabricated and incorporated into an optical 3 x 3 vector-vector or matrix-matrix multiplier system. This single element deflector is used as a outer-product device. The input vectors are addressed by electronic means and the outer product matrix is displayed as a 2-D array of optical (laser) pixels. In part II of this work a multichannel single element 2-D deflector was designed, fabricated and implemented into a Programmable Logic Array (PLA) optical computing system. This system can be used for: word equality detection, free space optical interconnections, half adder optical system implementation. The PLA system described in this dissertation has capability of word equality detection. The 2-D multichannel deflector that was designed and fabricated is capable of comparing 16 x 16 words every 316 nanoseconds. Each word is 8

  7. Mathematical modeling and computation of the optical response from nanostructures

    NASA Astrophysics Data System (ADS)

    Sun, Yuanchang

    This dissertation studies the computational modeling for nanostructures in response to external electromagnetic fields. Light-matter interactions on nanoscale are at the heart of nano-optics. To fully characterize the optical interactions with nanostructures quantum electrodynamics (QED) must be invoked, however, the required extremely intense computation and analysis prohibit QED from applications in nano-optics. To avoid the expensive computations and be able to seize the essential quantum effects a semiclassical model is developed. The wellposedness of the model partial differential equations is established. Emphasis is placed on the optical interactions with an individual nanostructure, excitons and biexcitons effects and finite-size effects are investigated. The crucial step of our model is to couple the electromagnetic fields with the motion of the excited particles to yield a new dielectric constant which contains quantum effects of interest. A novel feature of the dielectric constant is the wavevector-dependence which leads to a multi-wave propagation inside the medium. Additional boundary conditions are proposed to deal with this situation. We proceed with incorporating this dielectric constant to Maxwell's equations, and by solving a scattering problem the quantum effects can be captured in the scattered spectra.

  8. Computational wave optics library for C++: CWO++ library

    NASA Astrophysics Data System (ADS)

    Shimobaba, Tomoyoshi; Weng, Jiantong; Sakurai, Takahiro; Okada, Naohisa; Nishitsuji, Takashi; Takada, Naoki; Shiraki, Atsushi; Masuda, Nobuyuki; Ito, Tomoyoshi

    2012-05-01

    Diffraction calculations, such as the angular spectrum method and Fresnel diffractions, are used for calculating scalar light propagation. The calculations are used in wide-ranging optics fields: for example, Computer Generated Holograms (CGHs), digital holography, diffractive optical elements, microscopy, image encryption and decryption, three-dimensional analysis for optical devices and so on. However, increasing demands made by large-scale diffraction calculations have rendered the computational power of recent computers insufficient. We have already developed a numerical library for diffraction calculations using a Graphic Processing Unit (GPU), which was named the GWO library. However, this GWO library is not user-friendly, since it is based on C language and was also run only on a GPU. In this paper, we develop a new C++ class library for diffraction and CGH calculations, which is referred to as a CWO++ library, running on a CPU and GPU. We also describe the structure, performance, and usage examples of the CWO++ library. Program summaryProgram title: CWO++ Catalogue identifier: AELL_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AELL_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 109 809 No. of bytes in distributed program, including test data, etc.: 4 181 911 Distribution format: tar.gz Programming language: C++ Computer: General computers and general computers with NVIDIA GPUs Operating system: Windows XP, Vista, 7 Has the code been vectorized or parallelized?: Yes. 1 core processor used in CPU and many cores in GPU. RAM: 256 M bytes Classification: 18 External routines: CImg, FFTW Nature of problem: The CWO++ library provides diffraction calculations which are useful for Computer Generated Holograms (CGHs), digital holography, diffractive

  9. Control mechanism of double-rotator-structure ternary optical computer

    NASA Astrophysics Data System (ADS)

    Kai, SONG; Liping, YAN

    2017-03-01

    Double-rotator-structure ternary optical processor (DRSTOP) has two characteristics, namely, giant data-bits parallel computing and reconfigurable processor, which can handle thousands of data bits in parallel, and can run much faster than computers and other optical computer systems so far. In order to put DRSTOP into practical application, this paper established a series of methods, namely, task classification method, data-bits allocation method, control information generation method, control information formatting and sending method, and decoded results obtaining method and so on. These methods form the control mechanism of DRSTOP. This control mechanism makes DRSTOP become an automated computing platform. Compared with the traditional calculation tools, DRSTOP computing platform can ease the contradiction between high energy consumption and big data computing due to greatly reducing the cost of communications and I/O. Finally, the paper designed a set of experiments for DRSTOP control mechanism to verify its feasibility and correctness. Experimental results showed that the control mechanism is correct, feasible and efficient.

  10. Research of the grid computing system applied in optical simulation

    NASA Astrophysics Data System (ADS)

    Jin, Wei-wei; Wang, Yu-dong; Liu, Qiangsheng; Cen, Zhao-feng; Li, Xiao-tong; Lin, Yi-qun

    2008-03-01

    A grid computing in the field of optics is presented in this paper. Firstly, the basic principles and research background of grid computing are outlined in this paper, along with the overview of its applications and the development status quo. The paper also discusses several typical tasks scheduling algorithms. Secondly, it focuses on describing a task scheduling of grid computing applied in optical computation. The paper gives details about the task scheduling system, including the task partition, granularity selection and tasks allocation, especially the structure of the system. In addition, some details of communication on grid computing are also illustrated. In this system, the "makespan" and "load balancing" are comprehensively considered. Finally, we build a grid model to test the task scheduling strategy, and the results are analyzed in detail. Compared to one isolated computer, a grid comprised of one server and four processors can shorten the "makespan" to 1/4. At the same time, the experimental results of the simulation also illustrate that the proposed scheduling system is able to balance loads of all processors. In short, the system performs scheduling well in the grid environment.

  11. Note: Computer controlled rotation mount for large diameter optics

    NASA Astrophysics Data System (ADS)

    Rakonjac, Ana; Roberts, Kris O.; Deb, Amita B.; Kjærgaard, Niels

    2013-02-01

    We describe the construction of a motorized optical rotation mount with a 40 mm clear aperture. The device is used to remotely control the power of large diameter laser beams for a magneto-optical trap. A piezo-electric ultrasonic motor on a printed circuit board provides rotation with a precision better than 0.03° and allows for a very compact design. The rotation unit is controlled from a computer via serial communication, making integration into most software control platforms straightforward.

  12. Quantum Computation Using Optically Coupled Quantum Dot Arrays

    NASA Technical Reports Server (NTRS)

    Pradhan, Prabhakar; Anantram, M. P.; Wang, K. L.; Roychowhury, V. P.; Saini, Subhash (Technical Monitor)

    1998-01-01

    A solid state model for quantum computation has potential advantages in terms of the ease of fabrication, characterization, and integration. The fundamental requirements for a quantum computer involve the realization of basic processing units (qubits), and a scheme for controlled switching and coupling among the qubits, which enables one to perform controlled operations on qubits. We propose a model for quantum computation based on optically coupled quantum dot arrays, which is computationally similar to the atomic model proposed by Cirac and Zoller. In this model, individual qubits are comprised of two coupled quantum dots, and an array of these basic units is placed in an optical cavity. Switching among the states of the individual units is done by controlled laser pulses via near field interaction using the NSOM technology. Controlled rotations involving two or more qubits are performed via common cavity mode photon. We have calculated critical times, including the spontaneous emission and switching times, and show that they are comparable to the best times projected for other proposed models of quantum computation. We have also shown the feasibility of accessing individual quantum dots using the NSOM technology by calculating the photon density at the tip, and estimating the power necessary to perform the basic controlled operations. We are currently in the process of estimating the decoherence times for this system; however, we have formulated initial arguments which seem to indicate that the decoherence times will be comparable, if not longer, than many other proposed models.

  13. Noise thresholds for optical cluster-state quantum computation

    SciTech Connect

    Dawson, Christopher M.; Nielsen, Michael A.; Haselgrove, Henry L.

    2006-05-15

    In this paper we do a detailed numerical investigation of the fault-tolerant threshold for optical cluster-state quantum computation. Our noise model allows both photon loss and depolarizing noise, as a general proxy for all types of local noise other than photon loss noise. We obtain a threshold region of allowed pairs of values for the two types of noise. Roughly speaking, our results show that scalable optical quantum computing is possible in the combined presence of both noise types, provided that the loss probability is less than 3x10{sup -3} and the depolarization probability is less than 10{sup -4}. Our fault-tolerant protocol involves a number of innovations, including a method for syndrome extraction known as telecorrection, whereby repeated syndrome measurements are guaranteed to agree. This paper is an extended version of Dawson et al. [Phys. Rev. Lett. 96, 020501 (2006)].

  14. High-power laser arrays for optical computing

    NASA Astrophysics Data System (ADS)

    Zucker, Erik P.; Craig, Richard R.; Mehuys, David G.; Nam, Derek W.; Welch, David F.; Scifres, Donald R.

    1991-12-01

    We demonstrate both common electrode and addressable arrays of single mode semiconductor lasers suitable for optical computing and optical data storage. In the common electrode geometry, eight lasers have been fabricated on a single chip which show excellent spectral and power uniformity. Total optical power obtained from this array has been in excess of 1.2 Watts CW. We have also fabricated two and nine element monolithic, individually addressable arrays with emitter spacings between 10 jim and 150 p m. Separately addressed, each element emits in a single spatial mode to greater than 0.1 Watts. For the nine element array, uniformity of better than 1.0 nanometer in wavelength and 1 milliamp in operating current across the array has been obtained. Results on crosstalk and reliability of the arrays are presented.

  15. Optically Driven Spin Based Quantum Dots for Quantum Computing

    DTIC Science & Technology

    2008-01-01

    system approach to quantum optics, Lecture Notes in Physics (Springer, Berlin, 1993). [5] H. M. Wiseman and G. J. Milburn, Phys. Rev. Lett. 70, 548 (1993...Electrical Engineering and Computer Science Department of Physics Harrison M. Randall Laboratory of Physics The University of Michigan Ann Arbor, MI...48109 Phone: 734-764-4469 Email: dst@umich.edu Co-Principal Investigator: L.J. Sham Department of Physics The University of California – San

  16. Optical computing and image processing using photorefractive gallium arsenide

    NASA Technical Reports Server (NTRS)

    Cheng, Li-Jen; Liu, Duncan T. H.

    1990-01-01

    Recent experimental results on matrix-vector multiplication and multiple four-wave mixing using GaAs are presented. Attention is given to a simple concept of using two overlapping holograms in GaAs to do two matrix-vector multiplication processes operating in parallel with a common input vector. This concept can be used to construct high-speed, high-capacity, reconfigurable interconnection and multiplexing modules, important for optical computing and neural-network applications.

  17. Computational Nonlinear Optics: Femtosecond Atmospheric Light String Applications

    DTIC Science & Technology

    2006-09-20

    the famous Nonlinear Schr ~ dinger Equation pulse propagation model and to the many more recent propagation models proposed as an improvement on NLSE. In...per response, including the time for reviewing instructions, searching existing date sources, gathenng and maintaining the data needed, and...AND SUBTITLE 5. FUNDING NUMBERS Computational Nonlinear Optics: Femtosecond Atmospheric Light String Applications F4 9620-03-1-0194 6. AUTHOR(S) PI

  18. A Simple Physical Optics Algorithm Perfect for Parallel Computing

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.; Cwik, T.

    1993-01-01

    One of the simplest reflector antenna computer programs is based upon a discrete approximation of the radiation integral. This calculation replaces the actual reflector surface with a triangular facet representation so that the reflector resembles a geodesic dome. The Physical Optics (PO) current is assumed to be constant in magnitude and phase over each facet so the radiation integral is reduced to a simple summation. This program has proven to be surprisingly robust and useful for the analysis of arbitrary reflectors, particularly when the near-field is desired and surface derivatives are not known. Because of its simplicity, the algorithm has proven to be extremely easy to adapt to the parallel computing architecture of a modest number of large-grain computing elements such as are used in the Intel iPSC and Touchstone Delta parallel machines.

  19. Parallel processing using an optical delay-based reservoir computer

    NASA Astrophysics Data System (ADS)

    Van der Sande, Guy; Nguimdo, Romain Modeste; Verschaffelt, Guy

    2016-04-01

    Delay systems subject to delayed optical feedback have recently shown great potential in solving computationally hard tasks. By implementing a neuro-inspired computational scheme relying on the transient response to optical data injection, high processing speeds have been demonstrated. However, reservoir computing systems based on delay dynamics discussed in the literature are designed by coupling many different stand-alone components which lead to bulky, lack of long-term stability, non-monolithic systems. Here we numerically investigate the possibility of implementing reservoir computing schemes based on semiconductor ring lasers. Semiconductor ring lasers are semiconductor lasers where the laser cavity consists of a ring-shaped waveguide. SRLs are highly integrable and scalable, making them ideal candidates for key components in photonic integrated circuits. SRLs can generate light in two counterpropagating directions between which bistability has been demonstrated. We demonstrate that two independent machine learning tasks , even with different nature of inputs with different input data signals can be simultaneously computed using a single photonic nonlinear node relying on the parallelism offered by photonics. We illustrate the performance on simultaneous chaotic time series prediction and a classification of the Nonlinear Channel Equalization. We take advantage of different directional modes to process individual tasks. Each directional mode processes one individual task to mitigate possible crosstalk between the tasks. Our results indicate that prediction/classification with errors comparable to the state-of-the-art performance can be obtained even with noise despite the two tasks being computed simultaneously. We also find that a good performance is obtained for both tasks for a broad range of the parameters. The results are discussed in detail in [Nguimdo et al., IEEE Trans. Neural Netw. Learn. Syst. 26, pp. 3301-3307, 2015

  20. Optical interconnection networks for high-performance computing systems.

    PubMed

    Biberman, Aleksandr; Bergman, Keren

    2012-04-01

    Enabled by silicon photonic technology, optical interconnection networks have the potential to be a key disruptive technology in computing and communication industries. The enduring pursuit of performance gains in computing, combined with stringent power constraints, has fostered the ever-growing computational parallelism associated with chip multiprocessors, memory systems, high-performance computing systems and data centers. Sustaining these parallelism growths introduces unique challenges for on- and off-chip communications, shifting the focus toward novel and fundamentally different communication approaches. Chip-scale photonic interconnection networks, enabled by high-performance silicon photonic devices, offer unprecedented bandwidth scalability with reduced power consumption. We demonstrate that the silicon photonic platforms have already produced all the high-performance photonic devices required to realize these types of networks. Through extensive empirical characterization in much of our work, we demonstrate such feasibility of waveguides, modulators, switches and photodetectors. We also demonstrate systems that simultaneously combine many functionalities to achieve more complex building blocks. We propose novel silicon photonic devices, subsystems, network topologies and architectures to enable unprecedented performance of these photonic interconnection networks. Furthermore, the advantages of photonic interconnection networks extend far beyond the chip, offering advanced communication environments for memory systems, high-performance computing systems, and data centers.

  1. Reconfigurable optical interconnections via dynamic computer-generated holograms

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang (Inventor); Zhou, Shaomin (Inventor)

    1994-01-01

    A system is proposed for optically providing one-to-many irregular interconnections, and strength-adjustable many-to-many irregular interconnections which may be provided with strengths (weights) w(sub ij) using multiple laser beams which address multiple holograms and means for combining the beams modified by the holograms to form multiple interconnections, such as a cross-bar switching network. The optical means for interconnection is based on entering a series of complex computer-generated holograms on an electrically addressed spatial light modulator for real-time reconfigurations, thus providing flexibility for interconnection networks for largescale practical use. By employing multiple sources and holograms, the number of interconnection patterns achieved is increased greatly.

  2. Fault tolerance in parity-state linear optical quantum computing

    SciTech Connect

    Hayes, A. J. F.; Ralph, T. C.; Haselgrove, H. L.; Gilchrist, Alexei

    2010-08-15

    We use a combination of analytical and numerical techniques to calculate the noise threshold and resource requirements for a linear optical quantum computing scheme based on parity-state encoding. Parity-state encoding is used at the lowest level of code concatenation in order to efficiently correct errors arising from the inherent nondeterminism of two-qubit linear-optical gates. When combined with teleported error-correction (using either a Steane or Golay code) at higher levels of concatenation, the parity-state scheme is found to achieve a saving of approximately three orders of magnitude in resources when compared to the cluster state scheme, at a cost of a somewhat reduced noise threshold.

  3. Reconfigurable Optical Interconnections Via Dynamic Computer-Generated Holograms

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang (Inventor); Zhou, Shao-Min (Inventor)

    1996-01-01

    A system is presented for optically providing one-to-many irregular interconnections, and strength-adjustable many-to-many irregular interconnections which may be provided with strengths (weights) w(sub ij) using multiple laser beams which address multiple holograms and means for combining the beams modified by the holograms to form multiple interconnections, such as a cross-bar switching network. The optical means for interconnection is based on entering a series of complex computer-generated holograms on an electrically addressed spatial light modulator for real-time reconfigurations, thus providing flexibility for interconnection networks for large-scale practical use. By employing multiple sources and holograms, the number of interconnection patterns achieved is increased greatly.

  4. Linear optical quantum computing in a single spatial mode.

    PubMed

    Humphreys, Peter C; Metcalf, Benjamin J; Spring, Justin B; Moore, Merritt; Jin, Xian-Min; Barbieri, Marco; Kolthammer, W Steven; Walmsley, Ian A

    2013-10-11

    We present a scheme for linear optical quantum computing using time-bin-encoded qubits in a single spatial mode. We show methods for single-qubit operations and heralded controlled-phase (cphase) gates, providing a sufficient set of operations for universal quantum computing with the Knill-Laflamme-Milburn [Nature (London) 409, 46 (2001)] scheme. Our protocol is suited to currently available photonic devices and ideally allows arbitrary numbers of qubits to be encoded in the same spatial mode, demonstrating the potential for time-frequency modes to dramatically increase the quantum information capacity of fixed spatial resources. As a test of our scheme, we demonstrate the first entirely single spatial mode implementation of a two-qubit quantum gate and show its operation with an average fidelity of 0.84±0.07.

  5. Computationally efficient gradient matrix of optical path length in axisymmetric optical systems.

    PubMed

    Hsueh, Chun-Che; Lin, Psang-Dain

    2009-02-10

    We develop a mathematical method for determining the optical path length (OPL) gradient matrix relative to all the system variables such that the effects of variable changes can be evaluated in a single pass. The approach developed avoids the requirement for multiple ray-tracing operations and is, therefore, more computationally efficient. By contrast, the effects of variable changes on the OPL of an optical system are generally evaluated by utilizing a ray-tracing approach to determine the OPL before and after the variable change and then applying a finite-difference (FD) approximation method to estimate the OPL gradient with respect to each individual variable. Utilizing a Petzval lens system for verification purposes, it is shown that the approach developed reduces the computational time by around 90% compared to that of the FD method.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  7. Deblurring for spatial and temporal varying motion with optical computing

    NASA Astrophysics Data System (ADS)

    Xiao, Xiao; Xue, Dongfeng; Hui, Zhao

    2016-05-01

    A way to estimate and remove spatially and temporally varying motion blur is proposed, which is based on an optical computing system. The translation and rotation motion can be independently estimated from the joint transform correlator (JTC) system without iterative optimization. The inspiration comes from the fact that the JTC system is immune to rotation motion in a Cartesian coordinate system. The work scheme of the JTC system is designed to keep switching between the Cartesian coordinate system and polar coordinate system in different time intervals with the ping-pang handover. In the ping interval, the JTC system works in the Cartesian coordinate system to obtain a translation motion vector with optical computing speed. In the pang interval, the JTC system works in the polar coordinate system. The rotation motion is transformed to the translation motion through coordinate transformation. Then the rotation motion vector can also be obtained from JTC instantaneously. To deal with continuous spatially variant motion blur, submotion vectors based on the projective motion path blur model are proposed. The submotion vectors model is more effective and accurate at modeling spatially variant motion blur than conventional methods. The simulation and real experiment results demonstrate its overall effectiveness.

  8. Multiscale modeling and computation of optically manipulated nano devices

    SciTech Connect

    Bao, Gang; Liu, Di; Luo, Songting

    2016-07-01

    We present a multiscale modeling and computational scheme for optical-mechanical responses of nanostructures. The multi-physical nature of the problem is a result of the interaction between the electromagnetic (EM) field, the molecular motion, and the electronic excitation. To balance accuracy and complexity, we adopt the semi-classical approach that the EM field is described classically by the Maxwell equations, and the charged particles follow the Schrödinger equations quantum mechanically. To overcome the numerical challenge of solving the high dimensional multi-component many-body Schrödinger equations, we further simplify the model with the Ehrenfest molecular dynamics to determine the motion of the nuclei, and use the Time-Dependent Current Density Functional Theory (TD-CDFT) to calculate the excitation of the electrons. This leads to a system of coupled equations that computes the electromagnetic field, the nuclear positions, and the electronic current and charge densities simultaneously. In the regime of linear responses, the resonant frequencies initiating the out-of-equilibrium optical-mechanical responses can be formulated as an eigenvalue problem. A self-consistent multiscale method is designed to deal with the well separated space scales. The isomerization of azobenzene is presented as a numerical example.

  9. Linear Optical Quantum Computing in a Single Spatial Mode

    NASA Astrophysics Data System (ADS)

    Walmsley, Ian

    2014-05-01

    We present a scheme for linear optical quantum computing using time-bin encoded qubits in a single spatial mode. This scheme allows arbitrary numbers of qubits to be encoded in the same mode, circumventing the requirement for many spatial modes that challenges the scalability of other schemes, and exploiting the inherent stability and robustness of time-frequency optical modes. This approach leverages the architecture of modern telecommunications systems, and opens a door to very high dimensional Hilbert spaces while maintaining compact device designs. Further, temporal encodings benefit from intrinsic robustness to inhomogeneities in transmission mediums. These advantages have been recognized in works exploring the preparation of time-frequency entangled states both for tests of fundamental quantum phenomena, and for quantum communications technologies including key distribution and teleportation. Here we extend this idea to computation. In particular, we present methods for single-qubit operations and heralded controlled phase (CPhase) gates, providing a sufficient set of operations for universal quantum computing with the Knill-Laflamme-Milburn scheme. As a test of our scheme, we demonstrate the first entirely single spatial mode implementation of a two-qubit quantum gate and show its operation with an average fidelity of 0.84 /pm 0.07. An analysis of the performance of current technologies suggests that our scheme offers a promising route for the construction of quantum circuits beyond the few-qubit level. In addition, we foresee that our investigation may motivate further development of the approaches presented into a regime in which time bins are temporally overlapped and frequency based manipulations become necessary, opening up encodings of even higher densities. This work was supported by the Engineering and Physical Sciences Research Council (EP/H03031X/1), the European Commission project Q-ESSENCE (248095) and the Air Force Office of Scientific Research

  10. Computational Nanophotonics: Model Optical Interactions and Transport in Tailored Nanosystem Architectures

    SciTech Connect

    Stockman, Mark; Gray, Steven

    2014-02-21

    The program is directed toward development of new computational approaches to photoprocesses in nanostructures whose geometry and composition are tailored to obtain desirable optical responses. The emphasis of this specific program is on the development of computational methods and prediction and computational theory of new phenomena of optical energy transfer and transformation on the extreme nanoscale (down to a few nanometers).

  11. Optical computing with soliton trains in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Pinsker, Florian

    2015-12-01

    Optical computing devices can be implemented based on controlled generation of soliton trains in single and multicomponent Bose-Einstein condensates (BEC). Our concepts utilize the phenomenon that the frequency of soliton trains in BEC can be governed by changing interactions within the atom cloud [F. Pinsker, N. G. Berloff and V. M. Pérez-García, Phys. Rev. A87, 053624 (2013), arXiv:1305.4097]. We use this property to store numbers in terms of those frequencies for a short time until observation. The properties of soliton trains can be changed in an intended way by other components of BEC occupying comparable states or via phase engineering. We elucidate, in which sense, such an additional degree of freedom can be regarded as a tool for controlled manipulation of data. Finally, the outcome of any manipulation made is read out by observing the signature within the density profile.

  12. What can quantum optics say about computational complexity theory?

    PubMed

    Rahimi-Keshari, Saleh; Lund, Austin P; Ralph, Timothy C

    2015-02-13

    Considering the problem of sampling from the output photon-counting probability distribution of a linear-optical network for input Gaussian states, we obtain results that are of interest from both quantum theory and the computational complexity theory point of view. We derive a general formula for calculating the output probabilities, and by considering input thermal states, we show that the output probabilities are proportional to permanents of positive-semidefinite Hermitian matrices. It is believed that approximating permanents of complex matrices in general is a #P-hard problem. However, we show that these permanents can be approximated with an algorithm in the BPP^{NP} complexity class, as there exists an efficient classical algorithm for sampling from the output probability distribution. We further consider input squeezed-vacuum states and discuss the complexity of sampling from the probability distribution at the output.

  13. Resource Costs for Fault-Tolerant Linear Optical Quantum Computing

    NASA Astrophysics Data System (ADS)

    Li, Ying; Humphreys, Peter C.; Mendoza, Gabriel J.; Benjamin, Simon C.

    2015-10-01

    Linear optical quantum computing (LOQC) seems attractively simple: Information is borne entirely by light and processed by components such as beam splitters, phase shifters, and detectors. However, this very simplicity leads to limitations, such as the lack of deterministic entangling operations, which are compensated for by using substantial hardware overheads. Here, we quantify the resource costs for full-scale LOQC by proposing a specific protocol based on the surface code. With the caveat that our protocol can be further optimized, we report that the required number of physical components is at least 5 orders of magnitude greater than in comparable matter-based systems. Moreover, the resource requirements grow further if the per-component photon-loss rate is worse than 1 0-3 or the per-component noise rate is worse than 1 0-5. We identify the performance of switches in the network as the single most influential factor influencing resource scaling.

  14. Computer-aided interpretation approach for optical tomographic images

    NASA Astrophysics Data System (ADS)

    Klose, Christian D.; Klose, Alexander D.; Netz, Uwe J.; Scheel, Alexander K.; Beuthan, Jürgen; Hielscher, Andreas H.

    2010-11-01

    A computer-aided interpretation approach is proposed to detect rheumatic arthritis (RA) in human finger joints using optical tomographic images. The image interpretation method employs a classification algorithm that makes use of a so-called self-organizing mapping scheme to classify fingers as either affected or unaffected by RA. Unlike in previous studies, this allows for combining multiple image features, such as minimum and maximum values of the absorption coefficient for identifying affected and not affected joints. Classification performances obtained by the proposed method were evaluated in terms of sensitivity, specificity, Youden index, and mutual information. Different methods (i.e., clinical diagnostics, ultrasound imaging, magnet resonance imaging, and inspection of optical tomographic images), were used to produce ground truth benchmarks to determine the performance of image interpretations. Using data from 100 finger joints, findings suggest that some parameter combinations lead to higher sensitivities, while others to higher specificities when compared to single parameter classifications employed in previous studies. Maximum performances are reached when combining the minimum/maximum ratio of the absorption coefficient and image variance. In this case, sensitivities and specificities over 0.9 can be achieved. These values are much higher than values obtained when only single parameter classifications were used, where sensitivities and specificities remained well below 0.8.

  15. Computer-aided interpretation approach for optical tomographic images.

    PubMed

    Klose, Christian D; Klose, Alexander D; Netz, Uwe J; Scheel, Alexander K; Beuthan, Jurgen; Hielscher, Andreas H

    2010-01-01

    A computer-aided interpretation approach is proposed to detect rheumatic arthritis (RA) in human finger joints using optical tomographic images. The image interpretation method employs a classification algorithm that makes use of a so-called self-organizing mapping scheme to classify fingers as either affected or unaffected by RA. Unlike in previous studies, this allows for combining multiple image features, such as minimum and maximum values of the absorption coefficient for identifying affected and not affected joints. Classification performances obtained by the proposed method were evaluated in terms of sensitivity, specificity, Youden index, and mutual information. Different methods (i.e., clinical diagnostics, ultrasound imaging, magnet resonance imaging, and inspection of optical tomographic images), were used to produce ground truth benchmarks to determine the performance of image interpretations. Using data from 100 finger joints, findings suggest that some parameter combinations lead to higher sensitivities, while others to higher specificities when compared to single parameter classifications employed in previous studies. Maximum performances are reached when combining the minimum/maximum ratio of the absorption coefficient and image variance. In this case, sensitivities and specificities over 0.9 can be achieved. These values are much higher than values obtained when only single parameter classifications were used, where sensitivities and specificities remained well below 0.8.

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

    PubMed

    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.

  17. Holographic image processing, coherent optical computing, and neural computer architecture for pattern recognition

    NASA Astrophysics Data System (ADS)

    Schempp, Walter

    Metaplectic harmonic analysis is well matched with high resolution image processing. The metaplectic representation of the symplectic group and its twofold cover arises when the symplectic group is considered as a group of outer automorphisms of the irreducible linear representations of the Heisenberg two-step nilpotent Lie group. Starting with the Paley-Wiener theorem which forms the classical result for information-preserving sequential bandwidth compression, and its Stone-von Neumann-Segal analogue for the Heisenberg group which is at the basis of holographic reciprocity and coupling, the paper points out a unified metaplectic approach to signal geometry such as holographic image processing, coherent optical computing, and neural computer architecture for pattern recognition. Brief descriptions of hardware implementations are also included.

  18. Hyperparallel optical quantum computation assisted by atomic ensembles embedded in double-sided optical cavities

    NASA Astrophysics Data System (ADS)

    Li, Tao; Long, Gui-Lu

    2016-08-01

    We propose an effective, scalable, hyperparallel photonic quantum computation scheme in which photonic qubits are hyperencoded both in the spatial degrees of freedom (DOF) and the polarization DOF of each photon. The deterministic hyper-controlled-not (hyper-cnot) gate on a two-photon system is attainable with our interesting interface between the polarized photon and the collective spin wave (magnon) of an atomic ensemble embedded in a double-sided optical cavity, and it doubles the operations in the conventional quantum cnot gate. Moreover, we present a compact hyper-cnotN gate on N +1 hyperencoded photons with only two auxiliary cavity-magnon systems, not more, and it can be faithfully constituted with current experimental techniques. Our proposal enables various applications with the hyperencoded photons in quantum computing and quantum networks.

  19. CHRONICLE: First Workshop on Computer Optics (Zvenigorod, May 26-28, 1986)

    NASA Astrophysics Data System (ADS)

    Semenov, A. S.

    1986-12-01

    The First Workshop on Computer Optics was held on May 26-28, 1986, in a town of Zvenigorod close to Moscow and it was organized by the Council on Automation of Scientific Research (Physics Section), Joint Council on Optics (Planar Optics Section), and Institute of General Physics of the Academy of Sciences of the USSR with the support of the Division of General Physics and Astronomy of the Academy of Sciences of the USSR. About 100 scientists and specialists took part in the Workshop. The following topics were considered: computersynthesized components for planar optics; numerical methods in computer optics; systems for automatic design of planar optical components; nonlinear mechanisms of formation of wavefronts; technology of fabrication of computer optics components; automation of investigation of these components; hardware and software used in work on planar optics.

  20. Optimization of removal function in computer controlled optical surfacing

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Guo, Peiji; Ren, Jianfeng

    2010-10-01

    The technical principle of computer controlled optical surfacing (CCOS) and the common method of optimizing removal function that is used in CCOS are introduced in this paper. A new optimizing method time-sharing synthesis of removal function is proposed to solve problems of the removal function being far away from Gaussian type and slow approaching of the removal function error that encountered in the mode of planet motion or translation-rotation. Detailed time-sharing synthesis of using six removal functions is discussed. For a given region on the workpiece, six positions are selected as the centers of the removal function; polishing tool controlled by the executive system of CCOS revolves around each centre to complete a cycle in proper order. The overall removal function obtained by the time-sharing process is the ratio of total material removal in six cycles to time duration of the six cycles, which depends on the arrangement and distribution of the six removal functions. Simulations on the synthesized overall removal functions under two different modes of motion, i.e., planet motion and translation-rotation are performed from which the optimized combination of tool parameters and distribution of time-sharing synthesis removal functions are obtained. The evaluation function when optimizing is determined by an approaching factor which is defined as the ratio of the material removal within the area of half of the polishing tool coverage from the polishing center to the total material removal within the full polishing tool coverage area. After optimization, it is found that the optimized removal function obtained by time-sharing synthesis is closer to the ideal Gaussian type removal function than those by the traditional methods. The time-sharing synthesis method of the removal function provides an efficient way to increase the convergence speed of the surface error in CCOS for the fabrication of aspheric optical surfaces, and to reduce the intermediate- and high

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

    NASA Astrophysics Data System (ADS)

    Adie, Steven G.; Mulligan, Jeffrey A.

    2016-03-01

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

  2. The Need for Optical Means as an Alternative for Electronic Computing

    NASA Technical Reports Server (NTRS)

    Adbeldayem, Hossin; Frazier, Donald; Witherow, William; Paley, Steve; Penn, Benjamin; Bank, Curtis; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    An increasing demand for faster computers is rapidly growing to encounter the fast growing rate of Internet, space communication, and robotic industry. Unfortunately, the Very Large Scale Integration technology is approaching its fundamental limits beyond which the device will be unreliable. Optical interconnections and optical integrated circuits are strongly believed to provide the way out of the extreme limitations imposed on the growth of speed and complexity of nowadays computations by conventional electronics. This paper demonstrates two ultra-fast, all-optical logic gates and a high-density storage medium, which are essential components in building the future optical computer.

  3. Optical HAAR Wavelet Transforms using Computer Generated Holography

    DTIC Science & Technology

    1992-12-17

    This research introduces an optical implementation of the continuous wavelet transform to filter images. The wavelet transform is modeled as a...continuous wavelet transform was performed and that the results compared favorably to digital simulation. Wavelets, Holography, Optical correlators.

  4. Computation of the optical trapping force using an FDTD based technique.

    PubMed

    Gauthier, Robert

    2005-05-16

    The computation details related to computing the optical radiation pressure force on various objects using a 2-D grid FDTD algorithm are presented. The technique is based on propagating the electric and magnetic fields through the grid and determining the changes in the optical energy flow with and without the trap object(s) in the system. Traces displayed indicate that the optical forces and FDTD predicted object behavior are in agreement with published experiments and also determined through other computation techniques. We show computation results for a high and low dielectric disc and thin walled shell. The FDTD technique for computing the light-particle force interaction may be employed in all regimes relating particle dimensions to source wavelength. The algorithm presented here can be easily extended to 3-D and include torque computation algorithms, thus providing a highly flexible and universally useable computation engine.

  5. No-go theorem for passive single-rail linear optical quantum computing.

    PubMed

    Wu, Lian-Ao; Walther, Philip; Lidar, Daniel A

    2013-01-01

    Photonic quantum systems are among the most promising architectures for quantum computers. It is well known that for dual-rail photons effective non-linearities and near-deterministic non-trivial two-qubit gates can be achieved via the measurement process and by introducing ancillary photons. While in principle this opens a legitimate path to scalable linear optical quantum computing, the technical requirements are still very challenging and thus other optical encodings are being actively investigated. One of the alternatives is to use single-rail encoded photons, where entangled states can be deterministically generated. Here we prove that even for such systems universal optical quantum computing using only passive optical elements such as beam splitters and phase shifters is not possible. This no-go theorem proves that photon bunching cannot be passively suppressed even when extra ancilla modes and arbitrary number of photons are used. Our result provides useful guidance for the design of optical quantum computers.

  6. Experimental free-space optical network for massively parallel computers

    NASA Astrophysics Data System (ADS)

    Araki, S.; Kajita, M.; Kasahara, K.; Kubota, K.; Kurihara, K.; Redmond, I.; Schenfeld, E.; Suzaki, T.

    1996-03-01

    A free-space optical interconnection scheme is described for massively parallel processors based on the interconnection-cached network architecture. The optical network operates in a circuit-switching mode. Combined with a packet-switching operation among the circuit-switched optical channels, a high-bandwidth, low-latency network for massively parallel processing results. The design and assembly of a 64-channel experimental prototype is discussed, and operational results are presented.

  7. Optic Glomeruli: Biological Circuits that Compute Target Identity

    DTIC Science & Technology

    2013-11-01

    TERMS Optic glomeruli, glomerulus, Nasonia vitripennis, jewel wasp, Drosophila , vinegar fly, Giant Fiber, descending neuron, lobula, visual primitive...5 Figure 4. Optic glomerulus local interneuron in Drosophila . ...................................... 10 Figure 5. Giant fiber descending...studies are being performed on Drosophila , because genetic expression of green fluorescent protein provides identification of cell types in the living

  8. Coincident Pulse Techniques for Hybrid Electronic Optical Computer Systems

    DTIC Science & Technology

    1992-08-31

    parallel computer architectures, parallel algorithms, and VLSI . Additional interests include design tools and methodology for software, hardware, and...Interactive Toolset for Characterizing Complex Neural Systems" D.N. Krieger, T.W. Berger, S.P. Levitan, and R.J. Sclabassi; Computers and Mathematics, Vol...systims algorithm design, and computer aided design for VLSI . and the application of large computational arrays to scientific problems. Dr. Levitan is a

  9. A Simple Physical Optics Algorithm Perfect for Parallel Computing Architecture

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.; Cwik, T.

    1994-01-01

    A reflector antenna computer program based upon a simple discreet approximation of the radiation integral has proven to be extremely easy to adapt to the parallel computing architecture of the modest number of large-gain computing elements such as are used in the Intel iPSC and Touchstone Delta parallel machines.

  10. A technique for computation of star magnitudes relative to an optical sensor

    NASA Technical Reports Server (NTRS)

    Rhoads, J. W.

    1972-01-01

    The theory and techniques used to compute star magnitudes relative to any optical detector (such as the Mariner Mars 1971 Canopus star tracker) are described. Results are given relative to various star detectors.

  11. Exploration of operator method digital optical computers for application to NASA

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Digital optical computer design has been focused primarily towards parallel (single point-to-point interconnection) implementation. This architecture is compared to currently developing VHSIC systems. Using demonstrated multichannel acousto-optic devices, a figure of merit can be formulated. The focus is on a figure of merit termed Gate Interconnect Bandwidth Product (GIBP). Conventional parallel optical digital computer architecture demonstrates only marginal competitiveness at best when compared to projected semiconductor implements. Global, analog global, quasi-digital, and full digital interconnects are briefly examined as alternative to parallel digital computer architecture. Digital optical computing is becoming a very tough competitor to semiconductor technology since it can support a very high degree of three dimensional interconnect density and high degrees of Fan-In without capacitive loading effects at very low power consumption levels.

  12. A scheme of optical interconnection for super high speed parallel computer

    NASA Astrophysics Data System (ADS)

    Mao, Youju; Lv, Yi; Liu, Jiang; Dang, Mingrui

    2004-11-01

    An optical cross connection network which adopts coarse wavelength division multiplexing (CWDM) and data packet is introduced. It can be used to realize communication between multi-CPU and multi-MEM in parallel computing system. It provides an effective way to upgrade the capability of parallel computer by combining optical wavelength division multiplexing (WDM) and data packet switching technology. CWDM used in network construction, optical cross connection (OXC) based on optical switch arrays, and data packet format used in network construction were analyzed. We have also done the optimizing analysis of the number of optical switches needed in different scales of network in this paper. The architecture of the optical interconnection for 8 wavelength channels and 128 bits parallel transmission has been researched. Finally, a parallel transmission system with 4 nodes, 8 channels per node, has been designed.

  13. Development of a personal computer's viewing station for the IS&C magneto-optical disk.

    PubMed

    Ando, Y; Kunieda, E; Tsukamoto, N; Kawaguchi, O; Shigematsu, N; Kubo, A; Arai, Y

    1995-01-01

    We developed a display station for the medical images stored in the IS&C (Image Save and Carry) magneto-optical disk. This station consisted of the personal computer and the magneto-optical disk drive. The performance of this system was evaluated and was compared with the Unix workstations. We found that the personal computer system had an adequate ability to display medical images. It provided, moreover, for portability and practical use of medical information.

  14. Tracking of wet foam ageing by means of dynamic laser speckle and computer optical mouse

    NASA Astrophysics Data System (ADS)

    Guerrero, Jáder; Plata Planidina, Alexandra; Mejía-Ospino, Enrique; Cabanzo, Rafael

    2013-11-01

    Tracking of wet foam ageing by means of dynamic laser speckle and an optical flow sensor is presented. Using a computer optical mouse, like an optical flow sensor, a strong negative correlation between the average speed of the cursor and the coarsening of bubble was found. We used microscopic images to demonstrate that decreasing of speed is related with increasing of bubble size. The proposed setup allows sensitive measures, is not very expensive and highly portable.

  15. Deterministic linear-optics quantum computing based on a hybrid approach

    SciTech Connect

    Lee, Seung-Woo; Jeong, Hyunseok

    2014-12-04

    We suggest a scheme for all-optical quantum computation using hybrid qubits. It enables one to efficiently perform universal linear-optical gate operations in a simple and near-deterministic way using hybrid entanglement as off-line resources.

  16. Point spread function computation in normal incidence for rough optical surfaces

    NASA Astrophysics Data System (ADS)

    Tayabaly, Kashmira; Spiga, Daniele; Sironi, Giorgia; Canestrari, Rodolfo; Lavagna, Michele; Pareschi, Giovanni

    2016-08-01

    The Point Spread Function (PSF) allows for specifying the angular resolution of optical systems which is a key parameter used to define the performances of most optics. A prediction of the system's PSF is therefore a powerful tool to assess the design and manufacture requirements of complex optical systems. Currently, well-established ray-tracing routines based on a geometrical optics are used for this purpose. However, those ray-tracing routines either lack real surface defect considerations (figure errors or micro-roughness) in their computation, or they include a scattering effect modeled separately that requires assumptions difficult to verify. Since there is an increasing demand for tighter angular resolution, the problem of surface finishing could drastically damage the optical performances of a system, including optical telescopes systems. A purely physical optics approach is more effective as it remains valid regardless of the shape and size of the defects appearing on the optical surface. However, a computation when performed in the two-dimensional space is time consuming since it requires processing a surface map with a few micron resolution which sometimes extends the propagation to multiple-reflections. The computation is significantly simplified in the far-field configuration as it involves only a sequence of Fourier Transforms. We show how to account for measured surface defects and roughness in order to predict the performances of the optics in single reflection, which can be applied and validated for real case studies.

  17. Computational investigation on tunable optical band gap in armchair polyacenes

    SciTech Connect

    Das, Mousumi

    2015-08-14

    Polyacenes in their armchair geometry (phenacenes) have recently been found to possess appealing electronic and optical properties with higher chemical stability and comparatively larger band gap as compared to linear polyacenes. They also behave as high-temperature superconductors upon alkali metal doping. Moreover, the optical properties of crystalline picene can be finely tuned by applying external pressure. We investigated the variation of optical gap as a function of altering the interplanar distances between parallel cofacial phenacene dimers. We employed both time-dependent density functional theory and density matrix renormalization group (DMRG) technique to investigate the lowest singlet excitations in phenacene dimer. Our study showed that the lowest singlet excitation in these systems evolved as a function of interplanar separation. The optical excitation energy gap decreases as a function of inverse interplanar separation of the phenacene dimer. The distant dependent variation of optical absorption at the dimer level may be comparable with experimental observation in picene crystal under pressure. DMRG study also demonstrates that besides picene, electronic properties of higher phenacenes can also be tunable by altering interplanar separation.

  18. Optical backplane interconnect switch for data processors and computers

    NASA Technical Reports Server (NTRS)

    Hendricks, Herbert D.; Benz, Harry F.; Hammer, Jacob M.

    1989-01-01

    An optoelectronic integrated device design is reported which can be used to implement an all-optical backplane interconnect switch. The switch is sized to accommodate an array of processors and memories suitable for direct replacement into the basic avionic multiprocessor backplane. The optical backplane interconnect switch is also suitable for direct replacement of the PI bus traffic switch and at the same time, suitable for supporting pipelining of the processor and memory. The 32 bidirectional switchable interconnects are configured with broadcast capability for controls, reconfiguration, and messages. The approach described here can handle a serial interconnection of data processors or a line-to-link interconnection of data processors. An optical fiber demonstration of this approach is presented.

  19. Optical Computed Tomography for Imaging the Breast: First Look

    DTIC Science & Technology

    2000-07-01

    imaging through scattering walls using an ultrafast optical Kerr gate. Science; 253: 769-771, 1991 14. van der Mark MB, Hooft GW, Wachters AJH, de Vries UH...Pei Ho, Arthur E. T . Chiou, Editors, Proceedings of SPIE Vol. 4082 (2000) a 0277-786X/00/$15.00 1.2 Next-generation optical breast-imaging devices In...had developed different scanning configurations. van de Mark reported on use of continuous wave (CW) laser diodes at multi- wavelengths (679nm, 779nm

  20. Real-time optical flow computation based on adaptive color quantization by competitive neural networks

    NASA Astrophysics Data System (ADS)

    Grana Romay, Manuel; Echave, Imanol

    1999-08-01

    In this paper we prose the application of the codebook computed by the Self Organizing Map as a smoothing filter, the QV Bayesian Filter, for the preprocessing of the image sequences. The optical flow is then robustly and efficiently computed over the filtered imags applying a correlation approach at the pixel level.

  1. Photonic materials and devices for optical information processing and computing applications

    NASA Astrophysics Data System (ADS)

    Tanguay, Armand R., Jr.

    1991-02-01

    The research program is focused on a critical evaluation of advanced photonic materials and device concepts for the implementation of optical information processing and computing systems. The effort ranges from a detailed investigation of the fundamental physical and technological limitations that impact the potential computational gain (e.g., increases in throughput, decreases in decision time subsequent to processing, or minimization of the energy expended during computation) of optical information processing and computing systems, through the invention and characterization of key enabling devices such as two dimensional spatial light modulators and volume holographic optical elements, to the development of advanced techniques for materials growth, deposition, and processing that have a critical impact on potential device performance. This multifaceted evaluation of novel materials, device, and system concepts has been directly responsible for the invention and characterization of a number of photonic devices and materials processing techniques that exhibit both high performance and capacity for practical manufacturing. The primary program thrusts can be organized into three principal categories: (1) fundamental and technological limitations of optical information processing and computing; (2) electrically and optically addressed spatial light modulators; and (3) volume holographic optical elements.

  2. Teach Your Computer to Read: Scanners and Optical Character Recognition.

    ERIC Educational Resources Information Center

    Marsden, Jim

    1993-01-01

    Desktop scanners can be used with a software technology called optical character recognition (OCR) to convert the text on virtually any paper document into an electronic form. OCR offers educators new flexibility in incorporating text into tests, lesson plans, and other materials. (MLF)

  3. Computation and validation of two-dimensional PSF simulation based on physical optics

    NASA Astrophysics Data System (ADS)

    Tayabaly, K.; Spiga, D.; Sironi, G.; Canestrari, R.; Lavagna, M.; Pareschi, G.

    2015-09-01

    The Point Spread Function (PSF) is a key figure of merit for specifying the angular resolution of optical systems and, as the demand for higher and higher angular resolution increases, the problem of surface finishing must be taken seriously even in optical telescopes. From the optical design of the instrument, reliable ray-tracing routines allow computing and display of the PSF based on geometrical optics. However, such an approach does not directly account for the scattering caused by surface micro-roughness, which is interferential in nature. Although the scattering effect can be separately modeled, its inclusion in the ray-tracing routine requires assumptions that are difficult to verify. In that context, a purely physical optics approach is more appropriate as it remains valid regardless of the shape and size of the defects appearing on the optical surface. Such a computation, when performed in two-dimensional consideration, is memory and time consuming because it requires one to process a surface map with a few micron resolution, and the situation becomes even more complicated in case of optical systems characterized by more than one reflection. Fortunately, the computation is significantly simplified in far-field configuration, since the computation involves only a sequence of Fourier Transforms. In this paper, we provide validation of the PSF simulation with Physical Optics approach through comparison with real PSF measurement data in the case of ASTRI-SST M1 hexagonal segments. These results represent a first foundation stone for future development in a more advanced computation taking into account micro-roughness and multiple reflection in optical systems.

  4. Efficient parallel algorithms for optical computing with the discrete Fourier transform (DFT) primitive

    NASA Astrophysics Data System (ADS)

    Reif, John H.; Tyagi, Akhilesh

    1997-10-01

    Optical-computing technology offers new challenges to algorithm designers since it can perform an n -point discrete Fourier transform (DFT) computation in only unit time. Note that the DFT is a nontrivial computation in the parallel random-access machine model, a model of computing commonly used by parallel-algorithm designers. We develop two new models, the DFT VLSIO (very-large-scale integrated optics) and the DFT circuit, to capture this characteristic of optical computing. We also provide two paradigms for developing parallel algorithms in these models. Efficient parallel algorithms for many problems, including polynomial and matrix computations, sorting, and string matching, are presented. The sorting and string-matching algorithms are particularly noteworthy. Almost all these algorithms are within a polylog factor of the optical-computing (VLSIO) lower bounds derived by Barakat and Reif Appl. Opt. 26, 1015 (1987) and by Tyagi and Reif Proceedings of the Second IEEE Symposium on Parallel and Distributed Processing (Institute of Electrical and Electronics Engineers, New York, 1990) p. 14 .

  5. Computational modeling of femtosecond optical solitons from Maxwell's equations

    NASA Technical Reports Server (NTRS)

    Goorjian, Peter M.; Taflove, Allen; Joseph, Rose M.; Hagness, Susan C.

    1992-01-01

    An algorithm is developed that permits the direct time integration of full-vector nonlinear Maxwell's equations. This capability permits the modeling of both linear and nonlinear instantaneous and dispersive effects in the electric polarization in material media. The modeling of the optical carrier is retained. The fundamental innovation is to notice that it is possible to treat the linear and nonlinear convolution integrals, which describe the dispersion, as new dependent variables. A coupled system of nonlinear second-order ordinary differential equations can then be derived for the linear and nonlinear convolution integrals, by differentiating them in the time domain. These equations, together with Maxwell's equations, are solved to determine the electromagnetic fields in nonlinear dispersive media. Results are presented of calculations in one dimension of the propagation and collision of femtosecond electromagnetic solitons that retain the optical carrier, taking into account as the Kerr and Raman interactions.

  6. New Methods for Design and Computation of Freeform Optics

    DTIC Science & Technology

    2015-07-09

    as a partial differential equation(PDE) of second order with nonstandard boundary conditions. The solution to this PDE problem is a scalar function...the exact solution with any a priori given accuracy. By contrast with other approaches the solution obtained with our approach does not depend on ad hoc...strategy for constructing weak solutions to nonlinear partial differential equations arising in design problems involving freeform optical surfaces[10

  7. Optical Computing, 1991, Technical Digest Series, Vol. 6

    DTIC Science & Technology

    1992-05-22

    finite state machine is shown. (2) For sequential logic operations such as the execution of functional form of sum of products parallel feedback loop...University of Southern California. Fuzzy systems estimate 12:40 pm-2:00 pm Lunch Break sampled functions without a mathematical model of how outputs...the VSTEP is in realizing an optical interconnection device with functions which allow for compact configuration resulting from an absence of electric

  8. Computational Study of Linear and Nonlinear Optical Properties of Single Molecules and Clusters of Organic Electro-Optic Chromophores

    NASA Astrophysics Data System (ADS)

    Garrett, Kerry

    Organic electro-optic (OEO) materials integrated into silicon-organic hybrid (SOH) devices afford significant improvements in size, weight, power, and bandwidth (SWAP) performance of integrated electronic/photonic systems critical for current and next generation telecommunication, computer, sensor, transportation, and defense technologies. Improvement in molecular first hyperpolarizability, and in turn electro-optic activity, is crucial to further improvement in the performance of SOH devices. The timely preparation of new chromophores with improved molecular first hyperpolarizability requires theoretical guidance; however, common density functional theory (DFT) methods often perform poorly for optical properties in systems with substantial intramolecular charge transfer character. The first part of this dissertation describes the careful evaluation of popular long-range correction (LC) and range-separated hybrid (RSH) density functional theory (DFT) for definition of structure/function relationships crucial for the optimization of molecular first hyperpolarizability, beta. In particular, a benchmark set of well-characterized OEO chromophores is used to compare calculated results with the corresponding experimentally measured linear and nonlinear optical properties; respectively, the wavelength of the peak one-photon absorption energy, lambdamax, and beta. A goal of this work is to systematically determine the amount of exact exchange in LC/RSH-DFT methods required for accurately computing these properties for a variety OEO chromophores. High-level electron correlation (post-Hartree-Fock) methods are also investigated and compared with DFT. Included are results for the computation of beta using second-order Moller-Plesset perturbation theory (MP2) and the double-hybrid method, B2PLYP. The second part of this work transitions from single-molecule studies to computing bulk electronic and nonlinear optical properties of molecular crystals and isotropic ensembles of a

  9. An optical 2-dimensional correlator for pattern recognition in embedded computing

    SciTech Connect

    Molley, P.A.; Stalker, K.T.

    1988-01-01

    Optical processing technology can be applied to a variety of problems in embedded computing. It is particularly well suited for problems involving large two-dimensional arrays of data, for example in correlation based pattern recognition. For large kernel correlations, the parrellelism of optics offers the high throughput necessary to perform the desired correlation or convolution operations in real time. In addition, the latest generation of optical hardware provides the opportunity to construct processors ideally suited to the embedded computer environment because of their potential size, weight, and power consumption advantages over alternative technologies. Using currently available optical devices, one such architecture was constructed which demonstrated the ability to do real-time pattern recognition. The optical processor was able to perform a 2-D correlation of a 64 x 44 pixel reference object with a 256 x 232 pixel input image at standard video rates. This represents an equivalent computation rate of over 10 billion operations per second. Results of the optical processor as well as a discussion of the potential of this technology in the embedded computer enviroment.

  10. Comparison of computer-based and optical face recognition paradigms

    NASA Astrophysics Data System (ADS)

    Alorf, Abdulaziz A.

    The main objectives of this thesis are to validate an improved principal components analysis (IPCA) algorithm on images; designing and simulating a digital model for image compression, face recognition and image detection by using a principal components analysis (PCA) algorithm and the IPCA algorithm; designing and simulating an optical model for face recognition and object detection by using the joint transform correlator (JTC); establishing detection and recognition thresholds for each model; comparing between the performance of the PCA algorithm and the performance of the IPCA algorithm in compression, recognition and, detection; and comparing between the performance of the digital model and the performance of the optical model in recognition and detection. The MATLAB(c) software was used for simulating the models. PCA is a technique used for identifying patterns in data and representing the data in order to highlight any similarities or differences. The identification of patterns in data of high dimensions (more than three dimensions) is too difficult because the graphical representation of data is impossible. Therefore, PCA is a powerful method for analyzing data. IPCA is another statistical tool for identifying patterns in data. It uses information theory for improving PCA. The joint transform correlator (JTC) is an optical correlator used for synthesizing a frequency plane filter for coherent optical systems. The IPCA algorithm, in general, behaves better than the PCA algorithm in the most of the applications. It is better than the PCA algorithm in image compression because it obtains higher compression, more accurate reconstruction, and faster processing speed with acceptable errors; in addition, it is better than the PCA algorithm in real-time image detection due to the fact that it achieves the smallest error rate as well as remarkable speed. On the other hand, the PCA algorithm performs better than the IPCA algorithm in face recognition because it offers

  11. Theoretical Investigation of Optical Computing Based on Neural Network Models.

    DTIC Science & Technology

    1987-09-29

    34 Cognitive and Psychological Computation with Neu- ral Models," IEEE Trans. Sys., Man, and cyber., SMC-13, p. 799, 1983. 20’ K. Nakano, "Association-A...7),482(1986). 211 F. Rosenblatt, Principles of Neurodynamics : Perceptron and the The- ory of Brain Mechanisms, Spartan Books, Washington,(1961). 22

  12. Computer Generated Optical Illusions: A Teaching and Research Tool.

    ERIC Educational Resources Information Center

    Bailey, Bruce; Harman, Wade

    Interactive computer-generated simulations that highlight psychological principles were investigated in this study in which 33 female and 19 male undergraduate college student volunteers of median age 21 matched line and circle sizes in six variations of Ponzo's illusion. Prior to working with the illusions, data were collected based on subjects'…

  13. A Study of Computer-Aided Geometric Optical Design.

    DTIC Science & Technology

    1982-10-01

    WAHLSTEDT OCT B2 AFIT/GEP/PH/82D-24 UNCLASSIFIED F /’G 9/2 N smhohmohholi EohhhhhhhhhhhE 1111.2 1 .6 mmiima __’___ MICROCOPY RESOLUTION TEST CHART NATIONAL...The irting point () f the desigri was a Questar 3 inch telescope.. Avidj tional optic:l elements were added and " the design impoved until the desirF...The P|WI? J ) f e the lens is defined as the index of refractioni at ,ither focal point divided by the respective focal length. The power of the lens

  14. Synthesis of photochromic oligophenylenimines: optical and computational studies.

    PubMed

    Pérez, Armando I Martínez; Alonso, Oscar Coreño; Borbolla, Julián Cruz; Vásquez-Pérez, José M; Alonso, Juan Coreño; Ayala, Karina Alemán; Luna-Bárcenas, Gabriel; Pandiyan, Thangarasu; García, Rosa A Vázquez

    2015-03-27

    Phenyleneimine oligomers 4,4'-(((1E,1'E)-(((1E,1'E)-(1,4-phenylenebis-(azanylylidene))bis(methanylylidene))bis(2,5-bis(octyloxy)-4,1-phenylene))bis(methanylyl-idene))-bis(azanylylidene))dianiline (OIC1MS) and 7,7'-(((1E,1'E)-(((1E,1'E)-((9H-fluorene-2,7-diyl)bis(azanylylidene))bis(methanylylidene))bis(2,5-bis(octyloxy)-4,1phenylene))bis- (methanylylidene))bis(azanylylidene))bis(9H-fluoren-2-amine) (OIC2MS) were prepared by means of conventional and mechanochemical synthesis and characterized by FT-IR, 1H- and 13C-NMR techniques. The optical properties of the compounds were studied in solution by using UV-visible spectroscopy, and the optical effects were analyzed as a function of solvent. The results show that OIC2MS exhibits interesting photochromic properties. Furthermore, the structural and electronic properties of the compounds were analyzed by TD-DFT. It was found that the mechanosynthesis is an efficient method for the synthesis of both tetraimines.

  15. Optical image hiding based on computational ghost imaging

    NASA Astrophysics Data System (ADS)

    Wang, Le; Zhao, Shengmei; Cheng, Weiwen; Gong, Longyan; Chen, Hanwu

    2016-05-01

    Imaging hiding schemes play important roles in now big data times. They provide copyright protections of digital images. In the paper, we propose a novel image hiding scheme based on computational ghost imaging to have strong robustness and high security. The watermark is encrypted with the configuration of a computational ghost imaging system, and the random speckle patterns compose a secret key. Least significant bit algorithm is adopted to embed the watermark and both the second-order correlation algorithm and the compressed sensing (CS) algorithm are used to extract the watermark. The experimental and simulation results show that the authorized users can get the watermark with the secret key. The watermark image could not be retrieved when the eavesdropping ratio is less than 45% with the second-order correlation algorithm, whereas it is less than 20% with the TVAL3 CS reconstructed algorithm. In addition, the proposed scheme is robust against the 'salt and pepper' noise and image cropping degradations.

  16. Bragg optics computer codes for neutron scattering instrument design

    SciTech Connect

    Popovici, M.; Yelon, W.B.; Berliner, R.R.; Stoica, A.D.

    1997-09-01

    Computer codes for neutron crystal spectrometer design, optimization and experiment planning are described. Phase space distributions, linewidths and absolute intensities are calculated by matrix methods in an extension of the Cooper-Nathans resolution function formalism. For modeling the Bragg reflection on bent crystals the lamellar approximation is used. Optimization is done by satisfying conditions of focusing in scattering and in real space, and by numerically maximizing figures of merit. Examples for three-axis and two-axis spectrometers are given.

  17. Comment on: Computation of the optical trapping force using an FDTD based technique.

    PubMed

    Zhou, Fei; Gan, Xiaosong; Xu, Wendong; Gan, Fuxi

    2006-12-11

    In this comment, problems associated with an oversimplified FDTD based model used for trapping force calculation in recent papers "Computation of the optical trapping force using an FDTD based technique" [Opt. Express 13, 3707 (2005)], and "Rigorous time domain simulation of momentum transfer between light and microscopic particles in optical trapping" [Opt. Express 12, 2220 (2004)] are discussed. A more rigorous model using in Poynting vector is also presented.

  18. University of South Carolina CB Support, Basic Research in Materials and Techniques for Optical Computing Standoff Sensors

    DTIC Science & Technology

    2004-10-01

    computing elements of multivariate optical computing. Results of the first MOE tests revealed that near-theoretical performance could be obtained in the...simple situation tested . Mid-infrared, near-infrared and Raman spectra were acquired for nearly 50 organophosphorus compounds. Measurements were made on B...58 9.2.d Design and testing of a Multivariate Optical Element (MOE): The First Demonstration of Multivariate Optical Computing

  19. Study of a computer-controlled integrated optical gas-concentration sensor

    SciTech Connect

    Egorov, A A; Egorov, M A; Chekhlova, T K; Timakin, A G

    2008-08-31

    A computer-controlled integrated optical waveguide sensor based on an optical waveguide of the diffusion type with the low attenuation coefficient is developed and studied. It is shown that the response time of the sensor is {approx}0.15 s. According to tests and computer simulations, the sensor can detect gaseous ammonia in air with the limiting theoretical concentration of {approx}0.1 ppm for the signal-to-noise ratio no less than 20. (laser applications and other topics in quantum electronics)

  20. Computational multi-dimensional imaging based on compound-eye optics

    NASA Astrophysics Data System (ADS)

    Horisaki, Ryoichi; Nakamura, Tomoya; Tanida, Jun

    2014-11-01

    Artificial compound-eye optics have been used for three-dimensional information acquisition and display. It also enables us to realize a diversity of coded imaging process in each elemental optics. In this talk, we introduce our single-shot compound-eye imaging system to observe multi-dimensional information including depth, spectrum, and polarization based on compressive sensing. Furthermore it is applicable to increase the dynamic range and field-of-view. We also demonstrate an extended depth-of-field (DOF) cameras based on compound-eye optics. These extended DOF cameras physically or computationally implement phase modulations to increase the focusing range.

  1. Computational adaptive optics for live three-dimensional biological imaging

    PubMed Central

    Kam, Z.; Hanser, B.; Gustafsson, M. G. L.; Agard, D. A.; Sedat, J. W.

    2001-01-01

    Light microscopy of thick biological samples, such as tissues, is often limited by aberrations caused by refractive index variations within the sample itself. This problem is particularly severe for live imaging, a field of great current excitement due to the development of inherently fluorescent proteins. We describe a method of removing such aberrations computationally by mapping the refractive index of the sample using differential interference contrast microscopy, modeling the aberrations by ray tracing through this index map, and using space-variant deconvolution to remove aberrations. This approach will open possibilities to study weakly labeled molecules in difficult-to-image live specimens. PMID:11274396

  2. Programmable Optoelectronic Multiprocessors And Their Comparison With Symbolic Substitution For Digital Optical Computing

    NASA Astrophysics Data System (ADS)

    Kiamilev, F.; Esener, Sadik C.; Paturi, R.; Fainmar, Y.; Mercier, P.; Guest, C. C.; Lee, Sing H.

    1989-04-01

    This paper introduces programmable arrays of optically inter-connected electronic processors and compares them with conventional symbolic substitution (SS) systems. The comparison is made on the basis of computational efficiency, speed, size, energy utilization, programmability, and fault tolerance. The small grain size and space-invariant connections of SS lead to poor computational efficiency, difficult programming, and difficult incorporation of fault tolerance. Reliance on optical gates as its fundamental building elements is shown to give poor energy utilization. Programmable optoelectronic multiprocessor (POEM) systems, on the other hand, provide the architectural flexibility for good computational efficiency, use an energy-efficient combination of technologies, and support traditional programming methodologies and fault tolerance. Although the inherent clock speed of POEM systems is slower than that of SS systems, for most problems they will provide greater computational throughput. This comparison does not take into account the recent addition of crossover interconnect and space-variant masks to the SS architecture.

  3. DISCRETE EVENT SIMULATION OF OPTICAL SWITCH MATRIX PERFORMANCE IN COMPUTER NETWORKS

    SciTech Connect

    Imam, Neena; Poole, Stephen W

    2013-01-01

    In this paper, we present application of a Discrete Event Simulator (DES) for performance modeling of optical switching devices in computer networks. Network simulators are valuable tools in situations where one cannot investigate the system directly. This situation may arise if the system under study does not exist yet or the cost of studying the system directly is prohibitive. Most available network simulators are based on the paradigm of discrete-event-based simulation. As computer networks become increasingly larger and more complex, sophisticated DES tool chains have become available for both commercial and academic research. Some well-known simulators are NS2, NS3, OPNET, and OMNEST. For this research, we have applied OMNEST for the purpose of simulating multi-wavelength performance of optical switch matrices in computer interconnection networks. Our results suggest that the application of DES to computer interconnection networks provides valuable insight in device performance and aids in topology and system optimization.

  4. Computational challenges in atomic, molecular and optical physics.

    PubMed

    Taylor, Kenneth T

    2002-06-15

    Six challenges are discussed. These are the laser-driven helium atom; the laser-driven hydrogen molecule and hydrogen molecular ion; electron scattering (with ionization) from one-electron atoms; the vibrational and rotational structure of molecules such as H(3)(+) and water at their dissociation limits; laser-heated clusters; and quantum degeneracy and Bose-Einstein condensation. The first four concern fundamental few-body systems where use of high-performance computing (HPC) is currently making possible accurate modelling from first principles. This leads to reliable predictions and support for laboratory experiment as well as true understanding of the dynamics. Important aspects of these challenges addressable only via a terascale facility are set out. Such a facility makes the last two challenges in the above list meaningfully accessible for the first time, and the scientific interest together with the prospective role for HPC in these is emphasized.

  5. Considerations for the extension of coherent optical processors into the quantum computing regime

    NASA Astrophysics Data System (ADS)

    Young, Rupert C. D.; Birch, Philip M.; Chatwin, Chris R.

    2016-04-01

    Previously we have examined the similarities of the quantum Fourier transform to the classical coherent optical implementation of the Fourier transform (R. Young et al, Proc SPIE Vol 87480, 874806-1, -11). In this paper, we further consider how superposition states can be generated on coherent optical wave fronts, potentially allowing coherent optical processing hardware architectures to be extended into the quantum computing regime. In particular, we propose placing the pixels of a Spatial Light Modulator (SLM) individually in a binary superposition state and illuminating them with a coherent wave front from a conventional (but low intensity) laser source in order to make a so-called `interaction free' measurement. In this way, the quantum object, i.e. the individual pixels of the SLM in their superposition states, and the illuminating wavefront would become entangled. We show that if this were possible, it would allow the extension of coherent processing architectures into the quantum computing regime and we give an example of such a processor configured to recover one of a known set of images encrypted using the well-known coherent optical processing technique of employing a random Fourier plane phase encryption mask which classically requires knowledge of the corresponding phase conjugate key to decrypt the image. A quantum optical computer would allow interrogation of all possible phase masks in parallel and so immediate decryption.

  6. A Neural Model of How the Brain Computes Heading from Optic Flow in Realistic Scenes

    ERIC Educational Resources Information Center

    Browning, N. Andrew; Grossberg, Stephen; Mingolla, Ennio

    2009-01-01

    Visually-based navigation is a key competence during spatial cognition. Animals avoid obstacles and approach goals in novel cluttered environments using optic flow to compute heading with respect to the environment. Most navigation models try either explain data, or to demonstrate navigational competence in real-world environments without regard…

  7. SIMULATION STUDY FOR GASEOUS FLUXES FROM AN AREA SOURCE USING COMPUTED TOMOGRAPHY AND OPTICAL REMOTE SENSING

    EPA Science Inventory

    The paper presents a new approach to quantifying emissions from fugitive gaseous air pollution sources. Computed tomography (CT) and path-integrated optical remote sensing (PI-ORS) concentration data are combined in a new field beam geometry. Path-integrated concentrations are ...

  8. Computational Modeling of the Optical Rotation of Amino Acids: An "in Silico" Experiment for Physical Chemistry

    ERIC Educational Resources Information Center

    Simpson, Scott; Autschbach, Jochen; Zurek, Eva

    2013-01-01

    A computational experiment that investigates the optical activity of the amino acid valine has been developed for an upper-level undergraduate physical chemistry laboratory course. Hybrid density functional theory calculations were carried out for valine to confirm the rule that adding a strong acid to a solution of an amino acid in the l…

  9. Online object oriented Monte Carlo computational tool for the needs of biomedical optics

    PubMed Central

    Doronin, Alexander; Meglinski, Igor

    2011-01-01

    Conceptual engineering design and optimization of laser-based imaging techniques and optical diagnostic systems used in the field of biomedical optics requires a clear understanding of the light-tissue interaction and peculiarities of localization of the detected optical radiation within the medium. The description of photon migration within the turbid tissue-like media is based on the concept of radiative transfer that forms a basis of Monte Carlo (MC) modeling. An opportunity of direct simulation of influence of structural variations of biological tissues on the probing light makes MC a primary tool for biomedical optics and optical engineering. Due to the diversity of optical modalities utilizing different properties of light and mechanisms of light-tissue interactions a new MC code is typically required to be developed for the particular diagnostic application. In current paper introducing an object oriented concept of MC modeling and utilizing modern web applications we present the generalized online computational tool suitable for the major applications in biophotonics. The computation is supported by NVIDEA CUDA Graphics Processing Unit providing acceleration of modeling up to 340 times. PMID:21991540

  10. Concentrator optical characterization using computer mathematical modelling and point source testing

    NASA Technical Reports Server (NTRS)

    Dennison, E. W.; John, S. L.; Trentelman, G. F.

    1984-01-01

    The optical characteristics of a paraboloidal solar concentrator are analyzed using the intercept factor curve (a format for image data) to describe the results of a mathematical model and to represent reduced data from experimental testing. This procedure makes it possible not only to test an assembled concentrator, but also to evaluate single optical panels or to conduct non-solar tests of an assembled concentrator. The use of three-dimensional ray tracing computer programs to calculate the mathematical model is described. These ray tracing programs can include any type of optical configuration from simple paraboloids to array of spherical facets and can be adapted to microcomputers or larger computers, which can graphically display real-time comparison of calculated and measured data.

  11. Computational high-resolution optical imaging of the living human retina

    NASA Astrophysics Data System (ADS)

    Shemonski, Nathan D.; South, Fredrick A.; Liu, Yuan-Zhi; Adie, Steven G.; Scott Carney, P.; Boppart, Stephen A.

    2015-07-01

    High-resolution in vivo imaging is of great importance for the fields of biology and medicine. The introduction of hardware-based adaptive optics (HAO) has pushed the limits of optical imaging, enabling high-resolution near diffraction-limited imaging of previously unresolvable structures. In ophthalmology, when combined with optical coherence tomography, HAO has enabled a detailed three-dimensional visualization of photoreceptor distributions and individual nerve fibre bundles in the living human retina. However, the introduction of HAO hardware and supporting software adds considerable complexity and cost to an imaging system, limiting the number of researchers and medical professionals who could benefit from the technology. Here we demonstrate a fully automated computational approach that enables high-resolution in vivo ophthalmic imaging without the need for HAO. The results demonstrate that computational methods in coherent microscopy are applicable in highly dynamic living systems.

  12. Computational chemistry modeling and design of photoswitchable alignment materials for optically addressable liquid crystal devices

    NASA Astrophysics Data System (ADS)

    Marshall, K. L.; Sekera, E. R.; Xiao, K.

    2015-09-01

    Photoalignment technology based on optically switchable "command surfaces" has been receiving increasing interest for liquid crystal optics and photonics device applications. Azobenzene compounds in the form of low-molar-mass, watersoluble salts deposited either directly on the substrate surface or after dispersion in a polymer binder have been almost exclusively employed for these applications, and ongoing research in the area follows a largely empirical materials design and development approach. Recent computational chemistry advances now afford unprecedented opportunities to develop predictive capabilities that will lead to new photoswitchable alignment layer materials with low switching energies, enhanced bistability, write/erase fatigue resistance, and high laser-damage thresholds. In the work described here, computational methods based on the density functional theory and time-dependent density functional theory were employed to study the impact of molecular structure on optical switching properties in photoswitchable methacrylate and acrylamide polymers functionalized with azobenzene and spiropyran pendants.

  13. Small-computer program for optical design and analysis written in "C"

    NASA Astrophysics Data System (ADS)

    Beckmann, Leo H. J. F.

    1991-01-01

    The use of electronic computers in optical design and analysis is well established. In fact, optical calculations were among the first applications of the first computers that were built in the 40's, and Donald Feder, starting in 1951 [1], proved that the use of these machines went far beyond removing the tediousness of laborious calculations and offered new dimensions in understanding the actual design process [2]. By today's standards, of course, the equipment which had such a remarkable impact at its time, was primitive and slow. A modern inexpensive programmable calculator easily outperforms the any computers in both speed and memory capacity, not to mention accuracy and reliability. This also implies, that today, even computers at the low end of the cost and performance scale can be turned into remarkably powerful tools for optical design and analysis. This has been demonstrated for the class of programmable calculators [3] but applies, of course, even more convincingly to the present generation of low-cost personal computers, which are typically based on 16- or 32-bit processors, and where prices start well below $ 1000.-. Any degree of higher performance is available at steadily increased prices, so that there appears to be a fit for each requirement.

  14. Adaptive information interchange system of the fiber-optic measuring networks with the computer

    NASA Astrophysics Data System (ADS)

    Denisov, Igor V.; Drozdov, Roman S.; Sedov, Victor A.

    2005-06-01

    In the present paper the characteristics and opportunities of application of the system of parallel input-output of information from the fiber-optical measuring network into computer are considered. The system consists of two pars: on manframe and several expansion blocks. The first part is internal, is connected directly in the socket of the motherboard of the personal computer. It is designed for buffering system signals and development of cojmands of controlling by the system for input-output of signals into personal computer and signals generation onto expansion blocks. The second part is external, connects to the mainframe by means of cables. It designed for transformation of information from the fiber-optical measuring network into signalsof rthe mainframe and instrument settings adaptation. The analysis of speed of procesing of analog and digital data by system is presented. The possible schemes of use of the system for processing quasistationary and dynamic fields are considered.

  15. WDM package enabling high-bandwidth optical intrasystem interconnects for high-performance computer systems

    NASA Astrophysics Data System (ADS)

    Schrage, J.; Soenmez, Y.; Happel, T.; Gubler, U.; Lukowicz, P.; Mrozynski, G.

    2006-02-01

    From long haul, metro access and intersystem links the trend goes to applying optical interconnection technology at increasingly shorter distances. Intrasystem interconnects such as data busses between microprocessors and memory blocks are still based on copper interconnects today. This causes a bottleneck in computer systems since the achievable bandwidth of electrical interconnects is limited through the underlying physical properties. Approaches to solve this problem by embedding optical multimode polymer waveguides into the board (electro-optical circuit board technology, EOCB) have been reported earlier. The principle feasibility of optical interconnection technology in chip-to-chip applications has been validated in a number of projects. For reasons of cost considerations waveguides with large cross sections are used in order to relax alignment requirements and to allow automatic placement and assembly without any active alignment of components necessary. On the other hand the bandwidth of these highly multimodal waveguides is restricted due to mode dispersion. The advance of WDM technology towards intrasystem applications will provide sufficiently high bandwidth which is required for future high-performance computer systems: Assuming that, for example, 8 wavelength-channels with 12Gbps (SDR1) each are given, then optical on-board interconnects with data rates a magnitude higher than the data rates of electrical interconnects for distances typically found at today's computer boards and backplanes can be realized. The data rate will be twice as much, if DDR2 technology is considered towards the optical signals as well. In this paper we discuss an approach for a hybrid integrated optoelectronic WDM package which might enable the application of WDM technology to EOCB.

  16. Quantum computers based on electron spins controlled by ultrafast off-resonant single optical pulses.

    PubMed

    Clark, Susan M; Fu, Kai-Mei C; Ladd, Thaddeus D; Yamamoto, Yoshihisa

    2007-07-27

    We describe a fast quantum computer based on optically controlled electron spins in charged quantum dots that are coupled to microcavities. This scheme uses broadband optical pulses to rotate electron spins and provide the clock signal to the system. Nonlocal two-qubit gates are performed by phase shifts induced by electron spins on laser pulses propagating along a shared waveguide. Numerical simulations of this scheme demonstrate high-fidelity single-qubit and two-qubit gates with operation times comparable to the inverse Zeeman frequency.

  17. Digitizing stereoscopic optic nerve head photographs for storage and viewing using a personal computer.

    PubMed

    Nesher, Ronit; Zacharopoulos, Ioannis; Assia, Ehud I; Schuman, Joel S

    2005-01-01

    Careful examination and monitoring of optic nerve head changes is essential in the treatment of patients with glaucoma. This often results in accumulation of numerous photographs and required appropriate storage space. A simple, inexpensive, and efficient means of storing and viewing stereoscopic optic nerve head photographs is described. Images were acquired with a fundus camera, on a color slide film. Slides were then scanned and digitized. A handheld stereoscope was used for stereoscopic viewing on a computer monitor. A scanning resolution of 300 dpi appeared optimal. At this resolution, the storage utilization was 16 kilobytes and the scanning time was 160 seconds per patient.

  18. Computer simulation of the dynamic process of mark formation for magneto-optical memory

    NASA Astrophysics Data System (ADS)

    Hasegawa, Motoko; Moroga, Katsumi; Okada, Mitsuya; Okada, Osamu; Hidaka, Yasuharu

    1994-02-01

    A computer simulation method, based on the Landau-Lifshitz-Gilbert equation was developed in order to investigate the dynamics of magneto-optical recording and the mark writing process for the rare earth-transition metal amorphous magneto-optical layer was subsequently analyzed. It was found that the writing process depends sensitively on the spot radius of the irradiation laser. This result is discussed considering the reverse magnetized domain shrinking force, due to radial direction variation of wall energy density in a cylindrical domain model and the characteristics of the magnetic parameters. The writing process is especially affected by the temperature dependence of parameters in the region near the Curie temperature.

  19. SCRAM: A fast computational model for the optical performance of point focus solar central receiver systems

    NASA Astrophysics Data System (ADS)

    Bergeron, K. D.; Chiang, C. J.

    1980-04-01

    A mathematical approximation procedure, designated Sandia Central Receiver Approximation Model is described. A computational procedure which allows the user to define the heliostat field boundaries and tower height arbitrarily, generating a model for optical field performance, including shadowing, blocking, cosine, losses, and atmospheric attenuation, and which requires only a polynomial evaluation for each set of Sun angles was developed. One reason that the accuracy in field performance predictions is higher than that of the generating function for the model is that much of the error in the generating function is due to an oscillatory behavior associated with a moire pattern in the optical response of the heliostat field.

  20. The symmetric MSD encoder for one-step adder of ternary optical computer

    NASA Astrophysics Data System (ADS)

    Kai, Song; LiPing, Yan

    2016-08-01

    The symmetric Modified Signed-Digit (MSD) encoding is important for achieving the one-step MSD adder of Ternary Optical Computer (TOC). The paper described the symmetric MSD encoding algorithm in detail, and developed its truth table which has nine rows and nine columns. According to the truth table, the state table was developed, and the optical-path structure and circuit-implementation scheme of the symmetric MSD encoder (SME) for one-step adder of TOC were proposed. Finally, a series of experiments were designed and performed. The observed results of the experiments showed that the scheme to implement SME was correct, feasible and efficient.

  1. High-speed linear optics quantum computing using active feed-forward.

    PubMed

    Prevedel, Robert; Walther, Philip; Tiefenbacher, Felix; Böhi, Pascal; Kaltenbaek, Rainer; Jennewein, Thomas; Zeilinger, Anton

    2007-01-04

    As information carriers in quantum computing, photonic qubits have the advantage of undergoing negligible decoherence. However, the absence of any significant photon-photon interaction is problematic for the realization of non-trivial two-qubit gates. One solution is to introduce an effective nonlinearity by measurements resulting in probabilistic gate operations. In one-way quantum computation, the random quantum measurement error can be overcome by applying a feed-forward technique, such that the future measurement basis depends on earlier measurement results. This technique is crucial for achieving deterministic quantum computation once a cluster state (the highly entangled multiparticle state on which one-way quantum computation is based) is prepared. Here we realize a concatenated scheme of measurement and active feed-forward in a one-way quantum computing experiment. We demonstrate that, for a perfect cluster state and no photon loss, our quantum computation scheme would operate with good fidelity and that our feed-forward components function with very high speed and low error for detected photons. With present technology, the individual computational step (in our case the individual feed-forward cycle) can be operated in less than 150 ns using electro-optical modulators. This is an important result for the future development of one-way quantum computers, whose large-scale implementation will depend on advances in the production and detection of the required highly entangled cluster states.

  2. Parallel Photonic Quantum Computation Assisted by Quantum Dots in One-Side Optical Microcavities

    PubMed Central

    Luo, Ming-Xing; Wang, Xiaojun

    2014-01-01

    Universal quantum logic gates are important elements for a quantum computer. In contrast to previous constructions on one degree of freedom (DOF) of quantum systems, we investigate the possibility of parallel quantum computations dependent on two DOFs of photon systems. We construct deterministic hyper-controlled-not (hyper-CNOT) gates operating on the spatial-mode and the polarization DOFs of two-photon or one-photon systems by exploring the giant optical circular birefringence induced by quantum-dot spins in one-sided optical microcavities. These hyper-CNOT gates show that the quantum states of two DOFs can be viewed as independent qubits without requiring auxiliary DOFs in theory. This result can reduce the quantum resources by half for quantum applications with large qubit systems, such as the quantum Shor algorithm. PMID:25030424

  3. Planned development of a 3D computer based on free-space optical interconnects

    NASA Astrophysics Data System (ADS)

    Neff, John A.; Guarino, David R.

    1994-05-01

    Free-space optical interconnection has the potential to provide upwards of a million data channels between planes of electronic circuits. This may result in the planar board and backplane structures of today giving away to 3-D stacks of wafers or multi-chip modules interconnected via channels running perpendicular to the processor planes, thereby eliminating much of the packaging overhead. Three-dimensional packaging is very appealing for tightly coupled fine-grained parallel computing where the need for massive numbers of interconnections is severely taxing the capabilities of the planar structures. This paper describes a coordinated effort by four research organizations to demonstrate an operational fine-grained parallel computer that achieves global connectivity through the use of free space optical interconnects.

  4. Matrix-vector multiplication using digital partitioning for more accurate optical computing

    NASA Technical Reports Server (NTRS)

    Gary, C. K.

    1992-01-01

    Digital partitioning offers a flexible means of increasing the accuracy of an optical matrix-vector processor. This algorithm can be implemented with the same architecture required for a purely analog processor, which gives optical matrix-vector processors the ability to perform high-accuracy calculations at speeds comparable with or greater than electronic computers as well as the ability to perform analog operations at a much greater speed. Digital partitioning is compared with digital multiplication by analog convolution, residue number systems, and redundant number representation in terms of the size and the speed required for an equivalent throughput as well as in terms of the hardware requirements. Digital partitioning and digital multiplication by analog convolution are found to be the most efficient alogrithms if coding time and hardware are considered, and the architecture for digital partitioning permits the use of analog computations to provide the greatest throughput for a single processor.

  5. Time-Of-Flight Camera, Optical Tracker and Computed Tomography in Pairwise Data Registration

    PubMed Central

    Badura, Pawel; Juszczyk, Jan; Pietka, Ewa

    2016-01-01

    Purpose A growing number of medical applications, including minimal invasive surgery, depends on multi-modal or multi-sensors data processing. Fast and accurate 3D scene analysis, comprising data registration, seems to be crucial for the development of computer aided diagnosis and therapy. The advancement of surface tracking system based on optical trackers already plays an important role in surgical procedures planning. However, new modalities, like the time-of-flight (ToF) sensors, widely explored in non-medical fields are powerful and have the potential to become a part of computer aided surgery set-up. Connection of different acquisition systems promises to provide a valuable support for operating room procedures. Therefore, the detailed analysis of the accuracy of such multi-sensors positioning systems is needed. Methods We present the system combining pre-operative CT series with intra-operative ToF-sensor and optical tracker point clouds. The methodology contains: optical sensor set-up and the ToF-camera calibration procedures, data pre-processing algorithms, and registration technique. The data pre-processing yields a surface, in case of CT, and point clouds for ToF-sensor and marker-driven optical tracker representation of an object of interest. An applied registration technique is based on Iterative Closest Point algorithm. Results The experiments validate the registration of each pair of modalities/sensors involving phantoms of four various human organs in terms of Hausdorff distance and mean absolute distance metrics. The best surface alignment was obtained for CT and optical tracker combination, whereas the worst for experiments involving ToF-camera. Conclusion The obtained accuracies encourage to further develop the multi-sensors systems. The presented substantive discussion concerning the system limitations and possible improvements mainly related to the depth information produced by the ToF-sensor is useful for computer aided surgery developers

  6. Scalable photonic quantum computing assisted by quantum-dot spin in double-sided optical microcavity.

    PubMed

    Wei, Hai-Rui; Deng, Fu-Guo

    2013-07-29

    We investigate the possibility of achieving scalable photonic quantum computing by the giant optical circular birefringence induced by a quantum-dot spin in a double-sided optical microcavity as a result of cavity quantum electrodynamics. We construct a deterministic controlled-not gate on two photonic qubits by two single-photon input-output processes and the readout on an electron-medium spin confined in an optical resonant microcavity. This idea could be applied to multi-qubit gates on photonic qubits and we give the quantum circuit for a three-photon Toffoli gate. High fidelities and high efficiencies could be achieved when the side leakage to the cavity loss rate is low. It is worth pointing out that our devices work in both the strong and the weak coupling regimes.

  7. Physics education through computational tools: the case of geometrical and physical optics

    NASA Astrophysics Data System (ADS)

    Rodríguez, Y.; Santana, A.; Mendoza, L. M.

    2013-09-01

    Recently, with the development of more powerful and accurate computational tools, the inclusion of new didactic materials in the classroom is known to have increased. However, the form in which these materials can be used to enhance the learning process is still under debate. Many different methodologies have been suggested for constructing new relevant curricular material and, among them, just-in-time teaching (JiTT) has arisen as an effective and successful way to improve the content of classes. In this paper, we will show the implemented pedagogic strategies for the courses of geometrical and optical physics for students of optometry. Thus, the use of the GeoGebra software for the geometrical optics class and the employment of new in-house software for the physical optics class created using the high-level programming language Python is shown with the corresponding activities developed for each of these applets.

  8. A lower bound for routing on a completely connected optical communication parallel computer

    SciTech Connect

    Goldberg, L.A.; Jerrum, M.; MacKenzie, P.D.

    1993-08-03

    The task of routing a 2-relation on an n-processor completely connected optical communication parallel computer (OCPC) is considered. A lower bound is presented that applies to any randomized distributed algorithm for this task: specifically, it is shown that the expected number of steps required to route a 2-relation is {Omega}({radical} log log n) in the worst case. For comparison, the best upper bound known is O(log log n).

  9. Computer-aided manufacturing for freeform optical elements by ultraprecision micromilling

    NASA Astrophysics Data System (ADS)

    Stoebenau, Sebastian; Kleindienst, Roman; Hofmann, Meike; Sinzinger, Stefan

    2011-09-01

    The successful fabrication of several freeform optical elements by ultraprecision micromilling is presented in this article. We discuss in detail the generation of the tool paths using different variations of a computer-aided manufacturing (CAM) process. Following a classical CAM approach, a reflective beam shaper was fabricated. The approach is based on a solid model calculated by optical design software. As no analytical description of the surface is needed, this procedure is the most general solution for the programming of the tool paths. A second approach is based on the same design data. But instead of a solid model, a higher order polynomial was fitted to the data using computational methods. Taking advantage of the direct programming capabilities of state-of-the-art computerized numerical control units, the mathematics to calculate the polynomial based tool paths on-the-fly during the machining process are implemented in a highly flexible CNC code. As another example for this programming method, the fabrication of a biconic lens from a closed analytical description directly derived from the optical design is shown. We provide details about the different programming methods and the fabrication processes as well as the results of characterizations concerning surface quality and shape accuracy of the freeform optical elements.

  10. SCRAM: a fast computational model for the optical performance of point fucus solar central receiver systems

    SciTech Connect

    Bergeron, K. D.; Chiang, C. J.

    1980-04-01

    Because of the complexities of heliostat shadowing and blocking calculations, computational models for the optical performance of point focus central receiver (PFCR) systems tend to be too slow for many important applications, such as optimization studies based on performance with realistic weather data. In this paper, a mathematical approximation procedure, designated Sandia Central Receiver Approximation Model (SCRAM) will be described. Rather than simulating the system components from first principles, it relies on data generated by the DELSOL code of Dellin and Fish for the optical performance of PFCR systems, and abstracts a mathematical model using a stepwise regression procedure. The result is a computational procedure which allows the user to define the heliostat field boundaries and tower height arbitrarily, generating a model for optical field performance, including shadowing, blocking, cosine, losses, and atmospheric attenuation, and which requires only a polynomial evaluation for each set of sun angles. A comparison with DELSOL for three different fields on three representative days indicates that the rms error of the approximation is 1-3% and that the new code is 1,000-3,000 times as fast as DELSOL. It is also shown that one reason that the accuracy in field performance predictions is higher than that of the generting function for the model is that much of the error in the generating function is due to an oscillatory behavior associated with a moire pattern in the optical response of the heiostat field.

  11. Prehistological evaluation of benign and malignant pigmented skin lesions with optical computed tomography

    NASA Astrophysics Data System (ADS)

    Kokolakis, Athanasios; Zacharakis, Giannis; Krasagakis, Konstantin; Lasithiotakis, Konstantinos; Favicchio, Rosy; Spiliopoulos, George; Giannikaki, Elpida; Ripoll, Jorge; Tosca, Androniki

    2012-06-01

    Discrimination of benign and malignant melanocytic lesions is a major issue in clinical dermatology. Assessment of the thickness of melanoma is critical for prognosis and treatment selection. We aimed to evaluate a novel optical computed tomography (optical-CT) system as a tool for three-dimensional (3-D) imaging of melanocytic lesions and its ability to discriminate benign from malignant melanocytic lesions while simultaneously determining the thickness of invasive melanoma. Seventeen melanocytic lesions, one hemangioma, and normal skin were assessed immediately after their excision by optical-CT and subsequently underwent histopathological examination. Tomographic reconstructions were performed with a back-propagation algorithm calculating a 3-D map of the total attenuation coefficient (AC). There was a statistically significant difference between melanomas, dysplastic nevi, and non-dysplastic nevi, as indicated by Kruskal-Wallis test. Median AC values were higher for melanomas compared with dysplastic and non-dysplastic nevi. No statistically significant difference was observed when thickness values obtained by optical-CT were compared with histological thickness using a Wilcoxon sighed rank test. Our results suggest that optical-CT can be important for the immediate prehistological evaluation of biopsies, assisting the physician for a rapid assessment of malignancy and of the thickness of a melanocytic lesion.

  12. Graphene-assisted multiple-input high-base optical computing

    PubMed Central

    Hu, Xiao; Wang, Andong; Zeng, Mengqi; Long, Yun; Zhu, Long; Fu, Lei; Wang, Jian

    2016-01-01

    We propose graphene-assisted multiple-input high-base optical computing. We fabricate a nonlinear optical device based on a fiber pigtail cross-section coated with a single-layer graphene grown by chemical vapor deposition (CVD) method. An approach to implementing modulo 4 operations of three-input hybrid addition and subtraction of quaternary base numbers in the optical domain using multiple non-degenerate four-wave mixing (FWM) processes in graphene coated optical fiber device and (differential) quadrature phase-shift keying ((D)QPSK) signals is presented. We demonstrate 10-Gbaud modulo 4 operations of three-input quaternary hybrid addition and subtraction (A + B − C, A + C − B, B + C − A) in the experiment. The measured optical signal-to-noise ratio (OSNR) penalties for modulo 4 operations of three-input quaternary hybrid addition and subtraction (A + B − C, A + C − B, B + C − A) are measured to be less than 7 dB at a bit-error rate (BER) of 2 × 10−3. The BER performance as a function of the relative time offset between three signals (signal offset) is also evaluated showing favorable performance. PMID:27604866

  13. Graphene-assisted multiple-input high-base optical computing

    NASA Astrophysics Data System (ADS)

    Hu, Xiao; Wang, Andong; Zeng, Mengqi; Long, Yun; Zhu, Long; Fu, Lei; Wang, Jian

    2016-09-01

    We propose graphene-assisted multiple-input high-base optical computing. We fabricate a nonlinear optical device based on a fiber pigtail cross-section coated with a single-layer graphene grown by chemical vapor deposition (CVD) method. An approach to implementing modulo 4 operations of three-input hybrid addition and subtraction of quaternary base numbers in the optical domain using multiple non-degenerate four-wave mixing (FWM) processes in graphene coated optical fiber device and (differential) quadrature phase-shift keying ((D)QPSK) signals is presented. We demonstrate 10-Gbaud modulo 4 operations of three-input quaternary hybrid addition and subtraction (A + B - C, A + C - B, B + C - A) in the experiment. The measured optical signal-to-noise ratio (OSNR) penalties for modulo 4 operations of three-input quaternary hybrid addition and subtraction (A + B - C, A + C - B, B + C - A) are measured to be less than 7 dB at a bit-error rate (BER) of 2 × 10-3. The BER performance as a function of the relative time offset between three signals (signal offset) is also evaluated showing favorable performance.

  14. Scanning laser optical computed tomography system for large volume 3D dosimetry

    NASA Astrophysics Data System (ADS)

    Dekker, Kurtis H.; Battista, Jerry J.; Jordan, Kevin J.

    2017-04-01

    Stray light causes artifacts in optical computed tomography (CT) that negatively affect the accuracy of radiation dosimetry in gels or solids. Scatter effects are exacerbated by a large dosimeter volume, which is desirable for direct verification of modern radiotherapy treatment plans such as multiple-isocenter radiosurgery. The goal in this study was to design and characterize an optical CT system that achieves high accuracy primary transmission measurements through effective stray light rejection, while maintaining sufficient scan speed for practical application. We present an optical imaging platform that uses a galvanometer mirror for horizontal scanning, and a translation stage for vertical movement of a laser beam and small area detector for minimal stray light production and acceptance. This is coupled with a custom lens-shaped optical CT aquarium for parallel ray sampling of projections. The scanner images 15 cm diameter, 12 cm height cylindrical volumes at 0.33 mm resolution in approximately 30 min. Attenuation coefficients reconstructed from CT scans agreed with independent cuvette measurements within 2% for both absorbing and scattering solutions as well as small 1.25 cm diameter absorbing phantoms placed within a large, scattering medium that mimics gel. Excellent linearity between the optical CT scanner and the independent measurement was observed for solutions with between 90% and 2% transmission. These results indicate that the scanner should achieve highly accurate dosimetry of large volume dosimeters in a reasonable timeframe for clinical application to radiotherapy dose verification procedures.

  15. Scanning laser optical computed tomography system for large volume 3D dosimetry.

    PubMed

    Dekker, Kurtis H; Battista, Jerry J; Jordan, Kevin J

    2017-04-07

    Stray light causes artifacts in optical computed tomography (CT) that negatively affect the accuracy of radiation dosimetry in gels or solids. Scatter effects are exacerbated by a large dosimeter volume, which is desirable for direct verification of modern radiotherapy treatment plans such as multiple-isocenter radiosurgery. The goal in this study was to design and characterize an optical CT system that achieves high accuracy primary transmission measurements through effective stray light rejection, while maintaining sufficient scan speed for practical application. We present an optical imaging platform that uses a galvanometer mirror for horizontal scanning, and a translation stage for vertical movement of a laser beam and small area detector for minimal stray light production and acceptance. This is coupled with a custom lens-shaped optical CT aquarium for parallel ray sampling of projections. The scanner images 15 cm diameter, 12 cm height cylindrical volumes at 0.33 mm resolution in approximately 30 min. Attenuation coefficients reconstructed from CT scans agreed with independent cuvette measurements within 2% for both absorbing and scattering solutions as well as small 1.25 cm diameter absorbing phantoms placed within a large, scattering medium that mimics gel. Excellent linearity between the optical CT scanner and the independent measurement was observed for solutions with between 90% and 2% transmission. These results indicate that the scanner should achieve highly accurate dosimetry of large volume dosimeters in a reasonable timeframe for clinical application to radiotherapy dose verification procedures.

  16. Requirements for fault-tolerant factoring on an atom-optics quantum computer.

    PubMed

    Devitt, Simon J; Stephens, Ashley M; Munro, William J; Nemoto, Kae

    2013-01-01

    Quantum information processing and its associated technologies have reached a pivotal stage in their development, with many experiments having established the basic building blocks. Moving forward, the challenge is to scale up to larger machines capable of performing computational tasks not possible today. This raises questions that need to be urgently addressed, such as what resources these machines will consume and how large will they be. Here we estimate the resources required to execute Shor's factoring algorithm on an atom-optics quantum computer architecture. We determine the runtime and size of the computer as a function of the problem size and physical error rate. Our results suggest that once the physical error rate is low enough to allow quantum error correction, optimization to reduce resources and increase performance will come mostly from integrating algorithms and circuits within the error correction environment, rather than from improving the physical hardware.

  17. Computational optical palpation: micro-scale force mapping using finite-element methods (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wijesinghe, Philip; Sampson, David D.; Kennedy, Brendan F.

    2016-03-01

    Accurate quantification of forces, applied to, or generated by, tissue, is key to understanding many biomechanical processes, fabricating engineered tissues, and diagnosing diseases. Many techniques have been employed to measure forces; in particular, tactile imaging - developed to spatially map palpation-mimicking forces - has shown potential in improving the diagnosis of cancer on the macro-scale. However, tactile imaging often involves the use of discrete force sensors, such as capacitive or piezoelectric sensors, whose spatial resolution is often limited to 1-2 mm. Our group has previously presented a type of tactile imaging, termed optical palpation, in which the change in thickness of a compliant layer in contact with tissue is measured using optical coherence tomography, and surface forces are extracted, with a micro-scale spatial resolution, using a one-dimensional spring model. We have also recently combined optical palpation with compression optical coherence elastography (OCE) to quantify stiffness. A main limitation of this work, however, is that a one-dimensional spring model is insufficient in describing the deformation of mechanically heterogeneous tissue with uneven boundaries, generating significant inaccuracies in measured forces. Here, we present a computational, finite-element method, which we term computational optical palpation. In this technique, by knowing the non-linear mechanical properties of the layer, and from only the axial component of displacement measured by phase-sensitive OCE, we can estimate, not only the axial forces, but the three-dimensional traction forces at the layer-tissue interface. We use a non-linear, three-dimensional model of deformation, which greatly increases the ability to accurately measure force and stiffness in complex tissues.

  18. Direct ultrashort-pulse intensity and phase retrieval by frequency-resolved optical gating and a computational neural network.

    PubMed

    Krumbügel, M A; Ladera, C L; Delong, K W; Fittinghoff, D N; Sweetser, J N; Trebino, R

    1996-01-15

    Ultrashort-laser-pulse retrieval in frequency-resolved optical gating has previously required an iterative algorithm. Here, however, we show that a computational neural network can directly and rapidly recover the intensity and phase of a pulse.

  19. High performance optical encryption based on computational ghost imaging with QR code and compressive sensing technique

    NASA Astrophysics Data System (ADS)

    Zhao, Shengmei; Wang, Le; Liang, Wenqiang; Cheng, Weiwen; Gong, Longyan

    2015-10-01

    In this paper, we propose a high performance optical encryption (OE) scheme based on computational ghost imaging (GI) with QR code and compressive sensing (CS) technique, named QR-CGI-OE scheme. N random phase screens, generated by Alice, is a secret key and be shared with its authorized user, Bob. The information is first encoded by Alice with QR code, and the QR-coded image is then encrypted with the aid of computational ghost imaging optical system. Here, measurement results from the GI optical system's bucket detector are the encrypted information and be transmitted to Bob. With the key, Bob decrypts the encrypted information to obtain the QR-coded image with GI and CS techniques, and further recovers the information by QR decoding. The experimental and numerical simulated results show that the authorized users can recover completely the original image, whereas the eavesdroppers can not acquire any information about the image even the eavesdropping ratio (ER) is up to 60% at the given measurement times. For the proposed scheme, the number of bits sent from Alice to Bob are reduced considerably and the robustness is enhanced significantly. Meantime, the measurement times in GI system is reduced and the quality of the reconstructed QR-coded image is improved.

  20. Intrinsic parameterization of a computational optical system for long-distance displacement structural monitoring

    NASA Astrophysics Data System (ADS)

    Martins, Luís F. Lages; Rebordão, José Manuel N. V.; Ribeiro, Álvaro Silva

    2015-01-01

    We aim at the intrinsic parameterization of a computational optical system applied in long-distance displacement measurement of large-scale structures. In this structural-monitoring scenario, the observation distance established between the digital camera and reference targets, which is composed of the computational optical system, can range from 100 up to 1000 m, requiring the use of long-focal length lenses in order to obtain a suitable sensitivity for the three-dimensional displacement measurement of the observed structure which can be of reduced magnitude. Intrinsic parameterization of long-focal length cameras is an emergent issue since conventional approaches applied for reduced focal length cameras are not suitable mainly due to ill-conditioned matrices in least squares estimation procedures. We describe the intrinsic parameterization of a long-focal length camera (600 mm) by the diffractive optical element method and present the obtained estimates and measurement uncertainties, discussing their contribution for the system's validation by calibration field test and displacement measurement campaigns in a long-span suspension bridge.

  1. High numerical aperture diffractive optical elements for neutral atom quantum computing

    NASA Astrophysics Data System (ADS)

    Young, A. L.; Kemme, S. A.; Wendt, J. R.; Carter, T. R.; Samora, S.

    2013-03-01

    The viability of neutral atom based quantum computers is dependent upon scalability to large numbers of qubits. Diffractive optical elements (DOEs) offer the possibility to scale up to many qubit systems by enabling the manipulation of light to collect signal or deliver a tailored spatial trapping pattern. DOEs have an advantage over refractive microoptics since they do not have measurable surface sag, making significantly larger numerical apertures (NA) accessible with a smaller optical component. The smaller physical size of a DOE allows the micro-lenses to be placed in vacuum with the atoms, reducing aberration effects that would otherwise be introduced by the cell walls of the vacuum chamber. The larger collection angle accessible with DOEs enable faster quantum computation speeds. We have designed a set of DOEs for collecting the 852 nm fluorescence from the D2 transition in trapped cesium atoms, and compare these DOEs to several commercially available refractive micro-lenses. The largest DOE is able to collect over 20% of the atom's radiating sphere whereas the refractive micro-optic is able to collect just 8% of the atom's radiating sphere.

  2. Precision alignment and calibration of optical systems using computer generated holograms

    NASA Astrophysics Data System (ADS)

    Coyle, Laura Elizabeth

    As techniques for manufacturing and metrology advance, optical systems are being designed with more complexity than ever before. Given these prescriptions, alignment and calibration can be a limiting factor in their final performance. Computer generated holograms (CGHs) have several unique properties that make them powerful tools for meeting these demanding tolerances. This work will present three novel methods for alignment and calibration of optical systems using computer generated holograms. Alignment methods using CGHs require that the optical wavefront created by the CGH be related to a mechanical datum to locate it space. An overview of existing methods is provided as background, then two new alignment methods are discussed in detail. In the first method, the CGH contact Ball Alignment Tool (CBAT) is used to align a ball or sphere mounted retroreflector (SMR) to a Fresnel zone plate pattern with micron level accuracy. The ball is bonded directly onto the CGH substrate and provides permanent, accurate registration between the optical wavefront and a mechanical reference to locate the CGH in space. A prototype CBAT was built and used to align and bond an SMR to a CGH. In the second method, CGH references are used to align axi-symmetric optics in four degrees of freedom with low uncertainty and real time feedback. The CGHs create simultaneous 3D optical references where the zero order reflection sets tilt and the first diffracted order sets centration. The flexibility of the CGH design can be used to accommodate a wide variety of optical systems and maximize sensitivity to misalignments. A 2-CGH prototype system was aligned multiplied times and the alignment uncertainty was quantified and compared to an error model. Finally, an enhanced calibration method is presented. It uses multiple perturbed measurements of a master sphere to improve the calibration of CGH-based Fizeau interferometers ultimately measuring aspheric test surfaces. The improvement in the

  3. Organization of the channel-switching process in parallel computer systems based on a matrix optical switch

    NASA Technical Reports Server (NTRS)

    Golomidov, Y. V.; Li, S. K.; Popov, S. A.; Smolov, V. B.

    1986-01-01

    After a classification and analysis of electronic and optoelectronic switching devices, the design principles and structure of a matrix optical switch is described. The switching and pair-exclusion operations in this type of switch are examined, and a method for the optical switching of communication channels is elaborated. Finally, attention is given to the structural organization of a parallel computer system with a matrix optical switch.

  4. Micrometric precision of prosthetic dental crowns obtained by optical scanning and computer-aided designing/computer-aided manufacturing system.

    PubMed

    das Neves, Flávio Domingues; de Almeida Prado Naves Carneiro, Thiago; do Prado, Célio Jesus; Prudente, Marcel Santana; Zancopé, Karla; Davi, Letícia Resende; Mendonça, Gustavo; Soares, Carlos José

    2014-08-01

    The current study evaluated prosthetic dental crowns obtained by optical scanning and a computer-aided designing/computer-aided manufacturing system using micro-computed tomography to compare the marginal fit. The virtual models were obtained with four different scanning surfaces: typodont (T), regular impressions (RI), master casts (MC), and powdered master casts (PMC). Five virtual models were obtained for each group. For each model, a crown was designed on the software and milled from feldspathic ceramic blocks. Micro-CT images were obtained for marginal gap measurements and the data were statistically analyzed by one-way analysis of variance followed by Tukey's test. The mean vertical misfit was T = 62.6 ± 65.2 μm ; MC = 60.4 ± 38.4 μm; PMC = 58.1 ± 38.0 μm, and RI = 89.8 ± 62.8 μm. Considering a percentage of vertical marginal gap of up to 75 μm, the results were T = 71.5%, RI = 49.2%, MC = 69.6%, and PMC = 71.2%. The percentages of horizontal overextension were T = 8.5%, RI = 0%, MC = 0.8%, and PMC = 3.8%. Based on the results, virtual model acquisition by scanning the typodont (simulated mouth) or MC, with or without powder, showed acceptable values for the marginal gap. The higher result of marginal gap of the RI group suggests that it is preferable to scan this directly from the mouth or from MC.

  5. Micrometric precision of prosthetic dental crowns obtained by optical scanning and computer-aided designing/computer-aided manufacturing system

    NASA Astrophysics Data System (ADS)

    das Neves, Flávio Domingues; de Almeida Prado Naves Carneiro, Thiago; do Prado, Célio Jesus; Prudente, Marcel Santana; Zancopé, Karla; Davi, Letícia Resende; Mendonça, Gustavo; Soares, Carlos José

    2014-08-01

    The current study evaluated prosthetic dental crowns obtained by optical scanning and a computer-aided designing/computer-aided manufacturing system using micro-computed tomography to compare the marginal fit. The virtual models were obtained with four different scanning surfaces: typodont (T), regular impressions (RI), master casts (MC), and powdered master casts (PMC). Five virtual models were obtained for each group. For each model, a crown was designed on the software and milled from feldspathic ceramic blocks. Micro-CT images were obtained for marginal gap measurements and the data were statistically analyzed by one-way analysis of variance followed by Tukey's test. The mean vertical misfit was T=62.6±65.2 μm; MC=60.4±38.4 μm; PMC=58.1±38.0 μm, and RI=89.8±62.8 μm. Considering a percentage of vertical marginal gap of up to 75 μm, the results were T=71.5%, RI=49.2%, MC=69.6%, and PMC=71.2%. The percentages of horizontal overextension were T=8.5%, RI=0%, MC=0.8%, and PMC=3.8%. Based on the results, virtual model acquisition by scanning the typodont (simulated mouth) or MC, with or without powder, showed acceptable values for the marginal gap. The higher result of marginal gap of the RI group suggests that it is preferable to scan this directly from the mouth or from MC.

  6. A computer graphics reconstruction and optical analysis of scale anomalies in Caravaggio's Supper at Emmaus

    NASA Astrophysics Data System (ADS)

    Stork, David G.; Furuichi, Yasuo

    2011-03-01

    David Hockney has argued that the right hand of the disciple, thrust to the rear in Caravaggio's Supper at Emmaus (1606), is anomalously large as a result of the artist refocusing a putative secret lens-based optical projector and tracing the image it projected onto his canvas. We show through rigorous optical analysis that to achieve such an anomalously large hand image, Caravaggio would have needed to make extremely large, conspicuous and implausible alterations to his studio setup, moving both his purported lens and his canvas nearly two meters between "exposing" the disciple's left hand and then his right hand. Such major disruptions to his studio would have impeded -not aided- Caravaggio in his work. Our optical analysis quantifies these problems and our computer graphics reconstruction of Caravaggio's studio illustrates these problems. In this way we conclude that Caravaggio did not use optical projections in the way claimed by Hockney, but instead most likely set the sizes of these hands "by eye" for artistic reasons.

  7. Computer modeling and analysis of thermal link performance for an optical refrigerator

    NASA Astrophysics Data System (ADS)

    Byram, Kevin; Mar, David; Parker, John; Von der Porten, Steven; Hankinson, John; Lee, Chris; Mayeda, Kai; Haskell, Richard C.; Yang, Qimin; Greenfield, Scott R.; Epstein, Richard I.

    2008-02-01

    We have used the thermal modeling tool in COMSOL Multiphysics to investigate factors that affect the thermal performance of the optical refrigerator. Assuming an ideal cooling element and a non-absorptive dielectric trapping mirror, the three dominant heating factors are blackbody radiation from the surrounding environment, conductive heat transfer through mechanical supports, and the absorption of fluoresced photons transmitted through the thermal link. Laboratory experimentation coupled with computer modeling using Code V optical software have resulted in link designs capable of reducing the transmission to 0.04% of the fluoresced photons emitted toward the thermal link. The ideal thermal link will have minimal surface area, provide complete optical isolation for the load, and possess high thermal conductivity. Modeling results imply that a 1cm 3 load can be chilled to 102 K with currently available cooling efficiencies using a 100 W pump laser on a YB:ZBLANP system, and using an ideal link that has minimal surface area and no optical transmission. We review the simulated steady-state cooling temperatures reached by the heat load for several link designs and system configurations as a comparative measure of how well particular configurations perform.

  8. AZTECA, a y-y diagram oriented interactive computer program for optical system design and optimization

    NASA Astrophysics Data System (ADS)

    Flores-Hernandez, Ricardo

    1995-09-01

    The Centro de Investigaciones en Optica is developing the AZTECA optical design program to exploit the full synthesis capabilities intrinsic to Delano's y-y method. Both the y- y diagram and its dual the (omega) -(omega) diagram, are manipulated in real time to introduce changes at any point or line in those diagrams. These changes result in altered new versions of the optical system by means of a specialized subroutine that incorporates the fundamental synthesis equations for those diagrams. To display results on the computer's screen as the optimization process progress, AZTECA makes wide use of the fact that the y-y and the (omega) -(omega) diagrams display graphically all the first order attributes of an optical system. This program adjoins to these features the calculation of Buchdahl's 3rd, 5th, and 7th order aberration coefficients to the output. This results in a real time display of the system's paraxial and aberrational behavior. Efficient graphic displays, the program's modular structure and an interactive mode of operation, also contribute to make the AZTECA a versatile platform. It will be further developed as a new tool for efficient optical system design.

  9. MODA: a new algorithm to compute optical depths in multidimensional hydrodynamic simulations

    NASA Astrophysics Data System (ADS)

    Perego, Albino; Gafton, Emanuel; Cabezón, Rubén; Rosswog, Stephan; Liebendörfer, Matthias

    2014-08-01

    Aims: We introduce the multidimensional optical depth algorithm (MODA) for the calculation of optical depths in approximate multidimensional radiative transport schemes, equally applicable to neutrinos and photons. Motivated by (but not limited to) neutrino transport in three-dimensional simulations of core-collapse supernovae and neutron star mergers, our method makes no assumptions about the geometry of the matter distribution, apart from expecting optically transparent boundaries. Methods: Based on local information about opacities, the algorithm figures out an escape route that tends to minimize the optical depth without assuming any predefined paths for radiation. Its adaptivity makes it suitable for a variety of astrophysical settings with complicated geometry (e.g., core-collapse supernovae, compact binary mergers, tidal disruptions, star formation, etc.). We implement the MODA algorithm into both a Eulerian hydrodynamics code with a fixed, uniform grid and into an SPH code where we use a tree structure that is otherwise used for searching neighbors and calculating gravity. Results: In a series of numerical experiments, we compare the MODA results with analytically known solutions. We also use snapshots from actual 3D simulations and compare the results of MODA with those obtained with other methods, such as the global and local ray-by-ray method. It turns out that MODA achieves excellent accuracy at a moderate computational cost. In appendix we also discuss implementation details and parallelization strategies.

  10. Optical binary de Bruijn networks for massively parallel computing: design methodology and feasibility study

    NASA Astrophysics Data System (ADS)

    Louri, Ahmed; Sung, Hongki

    1995-10-01

    The interconnection network structure can be the deciding and limiting factor in the cost and the performance of parallel computers. One of the most popular point-to-point interconnection networks for parallel computers today is the hypercube. The regularity, logarithmic diameter, symmetry, high connectivity, fault tolerance, simple routing, and reconfigurability (easy embedding of other network topologies) of the hypercube make it a very attractive choice for parallel computers. Unfortunately the hypercube possesses a major drawback, which is the links per node increases as the network grows in size. As an alternative to the hypercube, the binary de Bruijn (BdB) network has recently received much attention. The BdB not only provides a logarithmic diameter, fault tolerance, and simple routing but also requires fewer links than the hypercube for the same network size. Additionally, a major advantage of the BdB edges per node is independent of the network size. This makes it very desirable for large-scale parallel systems. However, because of its asymmetrical nature and global connectivity, it poses a major challenge for VLSI technology. Optics, owing to its three-dimensional and global-connectivity nature, seems to be very suitable for implementing BdB networks. We present an implementation methodology for optical BdB networks. The distinctive feature of the proposed implementation methodology is partitionability of the network into a few primitive operations that can be implemented efficiently. We further show feasibility of the

  11. A scalable silicon photonic chip-scale optical switch for high performance computing systems.

    PubMed

    Yu, Runxiang; Cheung, Stanley; Li, Yuliang; Okamoto, Katsunari; Proietti, Roberto; Yin, Yawei; Yoo, S J B

    2013-12-30

    This paper discusses the architecture and provides performance studies of a silicon photonic chip-scale optical switch for scalable interconnect network in high performance computing systems. The proposed switch exploits optical wavelength parallelism and wavelength routing characteristics of an Arrayed Waveguide Grating Router (AWGR) to allow contention resolution in the wavelength domain. Simulation results from a cycle-accurate network simulator indicate that, even with only two transmitter/receiver pairs per node, the switch exhibits lower end-to-end latency and higher throughput at high (>90%) input loads compared with electronic switches. On the device integration level, we propose to integrate all the components (ring modulators, photodetectors and AWGR) on a CMOS-compatible silicon photonic platform to ensure a compact, energy efficient and cost-effective device. We successfully demonstrate proof-of-concept routing functions on an 8 × 8 prototype fabricated using foundry services provided by OpSIS-IME.

  12. Optical tomographic detection of rheumatoid arthritis with computer-aided classification schemes

    NASA Astrophysics Data System (ADS)

    Klose, Christian D.; Klose, Alexander D.; Netz, Uwe; Beuthan, Jürgen; Hielscher, Andreas H.

    2009-02-01

    A recent research study has shown that combining multiple parameters, drawn from optical tomographic images, leads to better classification results to identifying human finger joints that are affected or not affected by rheumatic arthritis RA. Building up on the research findings of the previous study, this article presents an advanced computer-aided classification approach for interpreting optical image data to detect RA in finger joints. Additional data are used including, for example, maximum and minimum values of the absorption coefficient as well as their ratios and image variances. Classification performances obtained by the proposed method were evaluated in terms of sensitivity, specificity, Youden index and area under the curve AUC. Results were compared to different benchmarks ("gold standard"): magnet resonance, ultrasound and clinical evaluation. Maximum accuracies (AUC=0.88) were reached when combining minimum/maximum-ratios and image variances and using ultrasound as gold standard.

  13. Visual analysis of the computer simulation for both imaging and non-imaging optical systems

    NASA Astrophysics Data System (ADS)

    Barladian, B. K.; Potemin, I. S.; Zhdanov, D. D.; Voloboy, A. G.; Shapiro, L. S.; Valiev, I. V.; Birukov, E. D.

    2016-10-01

    Typical results of the optic simulation are images generated on the virtual sensors of various kinds. As a rule, these images represent two-dimensional distribution of the light values in Cartesian coordinates (luminance, illuminance) or in polar coordinates (luminous intensity). Using the virtual sensors allows making the calculation and design of different kinds of illumination devices, providing stray light analysis, synthesizing of photorealistic images of three-dimensional scenes under the complex illumination generated with optical systems, etc. Based on rich experience in the development and practical using of computer systems of virtual prototyping and photorealistic visualization the authors formulated a number of basic requirements for the visualization and analysis of the results of light simulations represented as two-dimensional distribution of luminance, illuminance and luminous intensity values. The requirements include the tone mapping operators, pseudo color imaging, visualization of the spherical panorama, regression analysis, the analysis of the image sections and regions, analysis of pixel values, the image data export, etc. All those requirements were successfully satisfied in designed software component for visual analysis of the light simulation results. The module "LumiVue" is an integral part of "Lumicept" modeling system and the corresponding plug-in of computer-aided design and support for CATIA product. A number of visual examples of analysis of calculated two-dimensional distribution of luminous intensity, illuminance and luminance illustrate the article. The examples are results of simulation and design of lighting optical systems, secondary optics for LEDs, stray light analysis, virtual prototyping and photorealistic rendering.

  14. Monitoring of facial stress during space flight: Optical computer recognition combining discriminative and generative methods

    NASA Astrophysics Data System (ADS)

    Dinges, David F.; Venkataraman, Sundara; McGlinchey, Eleanor L.; Metaxas, Dimitris N.

    2007-02-01

    Astronauts are required to perform mission-critical tasks at a high level of functional capability throughout spaceflight. Stressors can compromise their ability to do so, making early objective detection of neurobehavioral problems in spaceflight a priority. Computer optical approaches offer a completely unobtrusive way to detect distress during critical operations in space flight. A methodology was developed and a study completed to determine whether optical computer recognition algorithms could be used to discriminate facial expressions during stress induced by performance demands. Stress recognition from a facial image sequence is a subject that has not received much attention although it is an important problem for many applications beyond space flight (security, human-computer interaction, etc.). This paper proposes a comprehensive method to detect stress from facial image sequences by using a model-based tracker. The image sequences were captured as subjects underwent a battery of psychological tests under high- and low-stress conditions. A cue integration-based tracking system accurately captured the rigid and non-rigid parameters of different parts of the face (eyebrows, lips). The labeled sequences were used to train the recognition system, which consisted of generative (hidden Markov model) and discriminative (support vector machine) parts that yield results superior to using either approach individually. The current optical algorithm methods performed at a 68% accuracy rate in an experimental study of 60 healthy adults undergoing periods of high-stress versus low-stress performance demands. Accuracy and practical feasibility of the technique is being improved further with automatic multi-resolution selection for the discretization of the mask, and automated face detection and mask initialization algorithms.

  15. Application of bilateral filtration with weight coefficients for similarity metric calculation in optical flow computation algorithm

    NASA Astrophysics Data System (ADS)

    Panin, S. V.; Titkov, V. V.; Lyubutin, P. S.; Chemezov, V. O.; Eremin, A. V.

    2016-11-01

    Application of weight coefficients of the bilateral filter used to determine weighted similarity metrics of image ranges in optical flow computation algorithm that employs 3-dimension recursive search (3DRS) was investigated. By testing the algorithm applying images taken from the public test database Middlebury benchmark, the effectiveness of this weighted similarity metrics for solving the image processing problem was demonstrated. The necessity of matching the equation parameter values when calculating the weight coefficients aimed at taking into account image texture features was proved for reaching the higher noise resistance under the vector field construction. The adaptation technique which allows excluding manual determination of parameter values was proposed and its efficiency was demonstrated.

  16. Approximate Bayesian computation for estimating number concentrations of monodisperse nanoparticles in suspension by optical microscopy

    NASA Astrophysics Data System (ADS)

    Röding, Magnus; Zagato, Elisa; Remaut, Katrien; Braeckmans, Kevin

    2016-06-01

    We present an approximate Bayesian computation scheme for estimating number concentrations of monodisperse diffusing nanoparticles in suspension by optical particle tracking microscopy. The method is based on the probability distribution of the time spent by a particle inside a detection region. We validate the method on suspensions of well-controlled reference particles. We illustrate its usefulness with an application in gene therapy, applying the method to estimate number concentrations of plasmid DNA molecules and the average number of DNA molecules complexed with liposomal drug delivery particles.

  17. A hybrid optical switch architecture to integrate IP into optical networks to provide flexible and intelligent bandwidth on demand for cloud computing

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Hall, Trevor J.

    2013-12-01

    The Internet is entering an era of cloud computing to provide more cost effective, eco-friendly and reliable services to consumer and business users. As a consequence, the nature of the Internet traffic has been fundamentally transformed from a pure packet-based pattern to today's predominantly flow-based pattern. Cloud computing has also brought about an unprecedented growth in the Internet traffic. In this paper, a hybrid optical switch architecture is presented to deal with the flow-based Internet traffic, aiming to offer flexible and intelligent bandwidth on demand to improve fiber capacity utilization. The hybrid optical switch is capable of integrating IP into optical networks for cloud-based traffic with predictable performance, for which the delay performance of the electronic module in the hybrid optical switch architecture is evaluated through simulation.

  18. An efficient approach for computing the geometrical optics field reflected from a numerically specified surface

    NASA Technical Reports Server (NTRS)

    Mittra, R.; Rushdi, A.

    1979-01-01

    An approach for computing the geometrical optic fields reflected from a numerically specified surface is presented. The approach includes the step of deriving a specular point and begins with computing the reflected rays off the surface at the points where their coordinates, as well as the partial derivatives (or equivalently, the direction of the normal), are numerically specified. Then, a cluster of three adjacent rays are chosen to define a 'mean ray' and the divergence factor associated with this mean ray. Finally, the ampilitude, phase, and vector direction of the reflected field at a given observation point are derived by associating this point with the nearest mean ray and determining its position relative to such a ray.

  19. Analysis of a dual-reflector antenna system using physical optics and digital computers

    NASA Technical Reports Server (NTRS)

    Schmidt, R. F.

    1972-01-01

    The application of physical-optics diffraction theory to a deployable dual-reflector geometry is discussed. The methods employed are not restricted to the Conical-Gregorian antenna, but apply in a general way to dual and even multiple reflector systems. Complex vector wave methods are used in the Fresnel and Fraunhofer regions of the reflectors. Field amplitude, phase, polarization data, and time average Poynting vectors are obtained via an IBM 360/91 digital computer. Focal region characteristics are plotted with the aid of a CalComp plotter. Comparison between the GSFC Huygens wavelet approach, JPL measurements, and JPL computer results based on the near field spherical wave expansion method are made wherever possible.

  20. Stray light in cone beam optical computed tomography: II. Reduction using a convergent light source

    NASA Astrophysics Data System (ADS)

    Dekker, Kurtis H.; Battista, Jerry J.; Jordan, Kevin J.

    2016-04-01

    Optical cone beam computed tomography (CBCT) using a broad beam and CCD camera is a fast method for densitometry of 3D optical gel dosimeters. However, diffuse light sources introduce considerable stray light into the imaging system, leading to underestimation of attenuation coefficients and non-uniformities in CT images unless corrections are applied to each projection image. In this study, the light source of a commercial optical CT scanner is replaced with a convergent cone beam source consisting of almost exclusively image forming primary rays. The convergent source is achieved using a small isotropic source and a Fresnel lens. To characterize stray light effects, full-field cone beam CT imaging is compared to fan beam CT (FBCT) using a 1 cm high fan beam aperture centered on the optic axis of the system. Attenuating liquids are scanned within a large 96 mm diameter uniform phantom and in a small 13.5 mm diameter finger phantom. For the uniform phantom, cone and fan beam CT attenuation coefficients agree within a maximum deviation of (1  ±  2)% between mean values over a wide range from 0.036 to 0.43 cm-1. For the finger phantom, agreement is found with a maximum deviation of (4  ±  2)% between mean values over a range of 0.1-0.47 cm-1. With the convergent source, artifacts associated with refractive index mismatch and vessel optical features are more pronounced. Further optimization of the source size to achieve a balance between quantitative accuracy and artifact reduction should enable practical, accurate 3D dosimetry, avoiding time consuming 3D scatter measurements.

  1. Stray light in cone beam optical computed tomography: II. Reduction using a convergent light source.

    PubMed

    Dekker, Kurtis H; Battista, Jerry J; Jordan, Kevin J

    2016-04-07

    Optical cone beam computed tomography (CBCT) using a broad beam and CCD camera is a fast method for densitometry of 3D optical gel dosimeters. However, diffuse light sources introduce considerable stray light into the imaging system, leading to underestimation of attenuation coefficients and non-uniformities in CT images unless corrections are applied to each projection image. In this study, the light source of a commercial optical CT scanner is replaced with a convergent cone beam source consisting of almost exclusively image forming primary rays. The convergent source is achieved using a small isotropic source and a Fresnel lens. To characterize stray light effects, full-field cone beam CT imaging is compared to fan beam CT (FBCT) using a 1 cm high fan beam aperture centered on the optic axis of the system. Attenuating liquids are scanned within a large 96 mm diameter uniform phantom and in a small 13.5 mm diameter finger phantom. For the uniform phantom, cone and fan beam CT attenuation coefficients agree within a maximum deviation of (1  ±  2)% between mean values over a wide range from 0.036 to 0.43 cm(-1). For the finger phantom, agreement is found with a maximum deviation of (4  ±  2)% between mean values over a range of 0.1-0.47 cm(-1). With the convergent source, artifacts associated with refractive index mismatch and vessel optical features are more pronounced. Further optimization of the source size to achieve a balance between quantitative accuracy and artifact reduction should enable practical, accurate 3D dosimetry, avoiding time consuming 3D scatter measurements.

  2. Application of optical tweezers using DOE and SLM to control of beads with information-DNA for photonic DNA computing

    NASA Astrophysics Data System (ADS)

    Zheng, M. J.; Ogura, Y.; Tanida, J.

    2008-03-01

    We have proposed photonic DNA computing as a new parallel computing paradigm, in which optical techniques are used to manipulate information-coded DNA. In this paper, we present a parallel transportation of multiple beads bound with hairpin-structure DNA using a dynamic optical tweezers system which combines a spatial light modulator (SLM) with a diffractive optical element (DOE). This system provides and effective method for parallel manipulations of DNA-bound beads at multiple positions. In the experiments, three 2.8-μm-diameter beads bound with hairpin DNA were trapped and transported in 1 μm of step by switching of the SLM patterns. The results demonstrate that the dynamic holographic optical tweezers system with combination of the DOE and the SLM is useful in spatially parallel processing required for photonic DNA computing.

  3. 25th anniversary article: Design of polymethine dyes for all-optical switching applications: guidance from theoretical and computational studies.

    PubMed

    Gieseking, Rebecca L; Mukhopadhyay, Sukrit; Risko, Chad; Marder, Seth R; Brédas, Jean-Luc

    2014-01-08

    All-optical switching--controlling light with light--has the potential to meet the ever-increasing demand for data transmission bandwidth. The development of organic π-conjugated molecular materials with the requisite properties for all-optical switching applications has long proven to be a significant challenge. However, recent advances demonstrate that polymethine dyes have the potential to meet the necessary requirements. In this review, we explore the theoretical underpinnings that guide the design of π-conjugated materials for all-optical switching applications. We underline, from a computational chemistry standpoint, the relationships among chemical structure, electronic structure, and optical properties that make polymethines such promising materials.

  4. Effective method to compute Franck-Condon integrals for optical spectra of large molecules in solution

    NASA Astrophysics Data System (ADS)

    Santoro, Fabrizio; Improta, Roberto; Lami, Alessandro; Bloino, Julien; Barone, Vincenzo

    2007-02-01

    The authors present a new method for the computation of vibrationally resolved optical spectra of large molecules, including the Duschinsky [Acta Physicochim. URSS 7, 551 (1937)] rotation of the normal modes. The method automatically selects the relevant vibronic contributions to the spectrum, independent of their frequency, and it is able to provide fully converged spectra with a quite modest computational time, both in vacuo and in condensed phase. Starting from the rigorous time-dependent expression they discuss indeed in which limits the spectrum of a molecule embedded in a solvent, described as a polarizable continuum, can be computed in a time-independent formalism, defining both nonequilibrium and equilibrium limits. In these cases the polarizable continuum model provides a suitable description of the solvent field. By computing the absorption spectra of anthracene in gas phase and of coumarin C153 in gas phase and cyclohexane, and the phosphorescence spectrum of the unsubstituted coumarin in ethanol they show that the method is fast and efficient.

  5. Effective method to compute Franck-Condon integrals for optical spectra of large molecules in solution.

    PubMed

    Santoro, Fabrizio; Improta, Roberto; Lami, Alessandro; Bloino, Julien; Barone, Vincenzo

    2007-02-28

    The authors present a new method for the computation of vibrationally resolved optical spectra of large molecules, including the Duschinsky [Acta Physicochim. URSS 7, 551 (1937)] rotation of the normal modes. The method automatically selects the relevant vibronic contributions to the spectrum, independent of their frequency, and it is able to provide fully converged spectra with a quite modest computational time, both in vacuo and in condensed phase. Starting from the rigorous time-dependent expression they discuss indeed in which limits the spectrum of a molecule embedded in a solvent, described as a polarizable continuum, can be computed in a time-independent formalism, defining both nonequilibrium and equilibrium limits. In these cases the polarizable continuum model provides a suitable description of the solvent field. By computing the absorption spectra of anthracene in gas phase and of coumarin C153 in gas phase and cyclohexane, and the phosphorescence spectrum of the unsubstituted coumarin in ethanol they show that the method is fast and efficient.

  6. Computation of the optical trapping force on small particles illuminated with a focused light beam using a FDTD method

    NASA Astrophysics Data System (ADS)

    Sun, Wei; Pan, Shi; Jiang, Yuchi

    2006-12-01

    According to the electromagnetic momentum interpretation due to Minkowski, the optical trapping force is determined by momentum transfer. The computation details related to computing the forces of optical radiation pressure on small particles using the scattered field three-dimensional (3D) grid finite difference time domain (FDTD) algorithm are presented. The technique is based on propagating the focused electromagnetic fields through the grid and determining the changes in the optical energy flow with and without the trapped object in the system. The Richards `Wolf vector field equations are applied to the scattered FDTD approach to specify an incident focused beam. We show computational results for a high refractive index particle. These results are in agreement with published experiments and are similar to other computational methods. Compared with some other calculation results using the FDTD method, our results are more consistent with the results measured.

  7. Design and Construction of an Optical Computed Tomography Scanner for Polymer Gel Dosimetry Application

    PubMed Central

    Zakariaee, Seyed Salman; Mesbahi, Asghar; Keshtkar, Ahmad; Azimirad, Vahid

    2014-01-01

    Polymer gel dosimeter is the only accurate three dimensional (3D) dosimeter that can measure the absorbed dose distribution in a perfect 3D setting. Gel dosimetry by using optical computed tomography (OCT) has been promoted by several researches. In the current study, we designed and constructed a prototype OCT system for gel dosimetry. First, the electrical system for optical scanning of the gel container using a Helium-Neon laser and a photocell was designed and constructed. Then, the mechanical part for two rotational and translational motions was designed and step motors were assembled to it. The data coming from photocell was grabbed by the home-built interface and sent to a personal computer. Data processing was carried out using MATLAB software. To calibrate the system and tune up the functionality of it, different objects was designed and scanned. Furthermore, the spatial and contrast resolution of the system was determined. The system was able to scan the gel dosimeter container with a diameter up to 11 cm inside the water phantom. The standard deviation of the pixels within water flask image was considered as the criteria for image uniformity. The uniformity of the system was about ±0.05%. The spatial resolution of the system was approximately 1 mm and contrast resolution was about 0.2%. Our primary results showed that this system is able to obtain two-dimensional, cross-sectional images from polymer gel samples. PMID:24761377

  8. Sophisticated test objects for the quality assurance of optical computed tomography scanners

    NASA Astrophysics Data System (ADS)

    Rahman, A. T. Abdul; Bräuer-Krisch, Elke; Brochard, Thierry; Adamovics, John; Clowes, S. K.; Bradley, David; Doran, Simon J.

    2011-07-01

    Optical computed tomography (CT), in conjunction with radiochromic gels and plastics, shows great potential for radiation therapy dose verification in 3D. However, an effective quality assurance (QA) regime for the various scanners currently available still remains to be developed. We show how the favourable properties of the PRESAGE® radiochromic polymer may be exploited to create highly sophisticated QA phantoms. Five 60 mm diameter cylindrical PRESAGE® samples were irradiated using the x-ray microbeam radiation therapy facility on the ID-17 biomedical beamline at the European Synchrotron Radiation Facility. Samples were then imaged on the University of Surrey parallel-beam optical CT scanner. The sample irradiations were designed to allow a variety of tests to be performed, including assessments of linearity, modulation transfer function (three independent measurements), geometric distortion and the effect of treatment fractionation. It is clear that, although the synchrotron method produces extremely high-quality test objects, it is not practical on a routine basis, because of its reliance on a highly specialized radiation source. Hence, we investigated a second possibility: three PRESAGE® samples were illuminated with ultraviolet light of wavelength 365 nm, using cheap masks created by laser-printing patterns onto overhead projector acetate sheets. There was good correlation between optical densities measured by the CT scanner and the expected UV 'dose' delivered. The results are encouraging and a proposal is made for a scanner test regime based on calibrated and well-characterized PRESAGE® samples.

  9. A Microscopic Optically Tracking Navigation System That Uses High-resolution 3D Computer Graphics.

    PubMed

    Yoshino, Masanori; Saito, Toki; Kin, Taichi; Nakagawa, Daichi; Nakatomi, Hirofumi; Oyama, Hiroshi; Saito, Nobuhito

    2015-01-01

    Three-dimensional (3D) computer graphics (CG) are useful for preoperative planning of neurosurgical operations. However, application of 3D CG to intraoperative navigation is not widespread because existing commercial operative navigation systems do not show 3D CG in sufficient detail. We have developed a microscopic optically tracking navigation system that uses high-resolution 3D CG. This article presents the technical details of our microscopic optically tracking navigation system. Our navigation system consists of three components: the operative microscope, registration, and the image display system. An optical tracker was attached to the microscope to monitor the position and attitude of the microscope in real time; point-pair registration was used to register the operation room coordinate system, and the image coordinate system; and the image display system showed the 3D CG image in the field-of-view of the microscope. Ten neurosurgeons (seven males, two females; mean age 32.9 years) participated in an experiment to assess the accuracy of this system using a phantom model. Accuracy of our system was compared with the commercial system. The 3D CG provided by the navigation system coincided well with the operative scene under the microscope. Target registration error for our system was 2.9 ± 1.9 mm. Our navigation system provides a clear image of the operation position and the surrounding structures. Systems like this may reduce intraoperative complications.

  10. Computational analysis and considerations of an optical fiber sensor with multiple cladding

    NASA Astrophysics Data System (ADS)

    Betancur, J. Alejandro

    2011-06-01

    Currently, fiber optic sensors are covering a great part of the automobile field, due to their precision, practicality and viability. At present, there are many theoretical and practical developments of fiber optic sensors focused towards the monitoring of thermal, torque and deformity variables, among other ones that are present in transportation vehicles. However, there is still a lot of exploration and investigation on this subject to be done, so that new analysis can be recognized and, consequently, new applications too. This work explains through MAPLE software, the computational analysis of the transverse electric and transverse magnetic modes generated in terms of Bessel functions, as a result of the light propagation through a fiber optic with different settings, proper of the type of sensor analyzed. This research exposes fundamental characters of measurement focused on the register of attributes of an object through. At the end, exposures and comments are made about the results obtained in graphics, showing the relation with the physical mathematical model described. The research for applications of this kind of technology is still scarce, for which it results necessary to investigate new types of analysis that can make possible the expansion of the technique to other fields of knowledge.

  11. Small-Field Measurements of 3D Polymer Gel Dosimeters through Optical Computed Tomography

    PubMed Central

    Shih, Cheng-Ting; Lee, Yao-Ting; Wu, Shin-Hua; Yao, Chun-Hsu; Hsieh, Bor-Tsung

    2016-01-01

    With advances in therapeutic instruments and techniques, three-dimensional dose delivery has been widely used in radiotherapy. The verification of dose distribution in a small field becomes critical because of the obvious dose gradient within the field. The study investigates the dose distributions of various field sizes by using NIPAM polymer gel dosimeter. The dosimeter consists of 5% gelatin, 5% monomers, 3% cross linkers, and 5 mM THPC. After irradiation, a 24 to 96 hour delay was applied, and the gel dosimeters were read by a cone beam optical computed tomography (optical CT) scanner. The dose distributions measured by the NIPAM gel dosimeter were compared to the outputs of the treatment planning system using gamma evaluation. For the criteria of 3%/3 mm, the pass rates for 5 × 5, 3 × 3, 2 × 2, 1 × 1, and 0.5 × 0.5 cm2 were as high as 91.7%, 90.7%, 88.2%, 74.8%, and 37.3%, respectively. For the criteria of 5%/5 mm, the gamma pass rates of the 5 × 5, 3 × 3, and 2 × 2 cm2 fields were over 99%. The NIPAM gel dosimeter provides high chemical stability. With cone-beam optical CT readouts, the NIPAM polymer gel dosimeter has potential for clinical dose verification of small-field irradiation. PMID:26974434

  12. Computational hydrodynamics and optical performance of inductively-coupled plasma adaptive lenses

    SciTech Connect

    Mortazavi, M.; Urzay, J. Mani, A.

    2015-06-15

    This study addresses the optical performance of a plasma adaptive lens for aero-optical applications by using both axisymmetric and three-dimensional numerical simulations. Plasma adaptive lenses are based on the effects of free electrons on the phase velocity of incident light, which, in theory, can be used as a phase-conjugation mechanism. A closed cylindrical chamber filled with Argon plasma is used as a model lens into which a beam of light is launched. The plasma is sustained by applying a radio-frequency electric current through a coil that envelops the chamber. Four different operating conditions, ranging from low to high powers and induction frequencies, are employed in the simulations. The numerical simulations reveal complex hydrodynamic phenomena related to buoyant and electromagnetic laminar transport, which generate, respectively, large recirculating cells and wall-normal compression stresses in the form of local stagnation-point flows. In the axisymmetric simulations, the plasma motion is coupled with near-wall axial striations in the electron-density field, some of which propagate in the form of low-frequency traveling disturbances adjacent to vortical quadrupoles that are reminiscent of Taylor-Görtler flow structures in centrifugally unstable flows. Although the refractive-index fields obtained from axisymmetric simulations lead to smooth beam wavefronts, they are found to be unstable to azimuthal disturbances in three of the four three-dimensional cases considered. The azimuthal striations are optically detrimental, since they produce high-order angular aberrations that account for most of the beam wavefront error. A fourth case is computed at high input power and high induction frequency, which displays the best optical properties among all the three-dimensional simulations considered. In particular, the increase in induction frequency prevents local thermalization and leads to an axisymmetric distribution of electrons even after introduction of

  13. Computational hydrodynamics and optical performance of inductively-coupled plasma adaptive lenses

    NASA Astrophysics Data System (ADS)

    Mortazavi, M.; Urzay, J.; Mani, A.

    2015-06-01

    This study addresses the optical performance of a plasma adaptive lens for aero-optical applications by using both axisymmetric and three-dimensional numerical simulations. Plasma adaptive lenses are based on the effects of free electrons on the phase velocity of incident light, which, in theory, can be used as a phase-conjugation mechanism. A closed cylindrical chamber filled with Argon plasma is used as a model lens into which a beam of light is launched. The plasma is sustained by applying a radio-frequency electric current through a coil that envelops the chamber. Four different operating conditions, ranging from low to high powers and induction frequencies, are employed in the simulations. The numerical simulations reveal complex hydrodynamic phenomena related to buoyant and electromagnetic laminar transport, which generate, respectively, large recirculating cells and wall-normal compression stresses in the form of local stagnation-point flows. In the axisymmetric simulations, the plasma motion is coupled with near-wall axial striations in the electron-density field, some of which propagate in the form of low-frequency traveling disturbances adjacent to vortical quadrupoles that are reminiscent of Taylor-Görtler flow structures in centrifugally unstable flows. Although the refractive-index fields obtained from axisymmetric simulations lead to smooth beam wavefronts, they are found to be unstable to azimuthal disturbances in three of the four three-dimensional cases considered. The azimuthal striations are optically detrimental, since they produce high-order angular aberrations that account for most of the beam wavefront error. A fourth case is computed at high input power and high induction frequency, which displays the best optical properties among all the three-dimensional simulations considered. In particular, the increase in induction frequency prevents local thermalization and leads to an axisymmetric distribution of electrons even after introduction of

  14. Multichannel Integrated Acoustooptic Device Modules for Signal Processing, Computing and Optical Interconnect.

    NASA Astrophysics Data System (ADS)

    Le, Phat Duc

    A variety of lithium niobate (LiNbO_3 )-based multichannel integrated optic (IO) device modules for applications in signal processing, computing, and optical interconnect have been realized. The key to the realization of these device modules is the titanium -indiffusion proton-exchange (TIPE) technique developed recently at our laboratory for fabrication of microlenses and microlens arrays. First, two ten-channel IO device modules have been constructed and tested. These two high -packing density devices modules represent the highest degree of integration and the largest number of components that have been accomplished thus far. The architecture common to both modules consists of a composite waveguide 1.0 x 2.0 cm^2 in size in which a channel -waveguide array, a planar waveguide, a linear microlens array, an electrooptic Bragg modulator array or an acoustooptic and electrooptic Bragg modulator array, and a large-aperture lens are integrated. These device modules have been used to perform matrix-matrix multiplications and digital correlations with encouraging results. In performing these computations, a convenient scheme that utilizes a linear ion-milled planar microlens array, devised specifically for these multichannel device modules, has been employed for simultaneous and efficient excitation of the entire channel-waveguide array. Secondly, a new type of strictly nonblocking IO switching network has been conceived and realized in LiNbO_3 . In this new optical switching network module two arrays of channel waveguides, a pair of large-aperture TIPE lenses, and a set of surface-acoustic-wave (SAW) transducers are configured such that the acoustooptic Bragg diffraction serves as a means to activate the connection between any input and any output channels. The working principle of this guided-wave acoustooptic switching network has been verified by using a 4 x 4 switching network module with encouraging performance such as a typical crosstalk level of -16 dB.

  15. Rapid Classification of Imaged Objects Using Molecular Factor and Multivariate Optical Computing

    NASA Astrophysics Data System (ADS)

    Pearl, Megan Renee

    Unique algorithm development is vital for the success of novel instrumentation. Our lab has focused on the design of imaging systems based on molecular factor and multivariate optical computing. A simulation-driven design approach was utilized to develop a multimode infrared imaging system for chemical contrast enhancement. This infrared thermal imaging system is based on molecular factor (MFC) and lockin computing methods. MFC was accomplished with filter elements made of thin organic films deposited on IR-transparent substrates and allows a system response to be tuned to a specific analyte. Unique algorithms were written in-house using MatLabRTM (The Mathworks, Natick, MA). The algorithms used a lock-in computing technique to amplify the diffuse re ectance signal, which is only a few percent of the total signal. Intensive thin film studies were conducted to understand the effects of films on fabric to improve our simulation-driven design approach. A prototype instrument has been validated through the production of a real setup. We have shown that it is able to detect trace amounts of blood diluted in water (as small as 1:100) on fabric as well as differentiate blood from common false positives of other blood detection methods (i.e., luminol). The second imaging system was designed for the differentiation of phytoplankton species in the ocean. Multivariate optical computing (MOC) was applied to the uorescence excitation spectra of individual phytoplankton cells to design multivariate optical elements (MOEs). MOEs are filters fabricated to mimic linear discriminants analysis (LDA) results based on plankton spectroscopy. The imaging system uses these MOEs housed in a filter wheel to produce "streak" images of phytoplankton as they flow past a CCD camera, with each streak having the appearance of a barcode whose intensities are related to scores of the plankton spectra on linear discriminant functions. Algorithms for this system have been designed to automatically

  16. Spatial light modulator phase mask implementation of wavefront encoded 3D computational-optical microscopy.

    PubMed

    King, Sharon V; Doblas, Ana; Patwary, Nurmohammed; Saavedra, Genaro; Martínez-Corral, Manuel; Preza, Chrysanthe

    2015-10-10

    Spatial light modulator (SLM) implementation of wavefront encoding enables various types of engineered point-spread functions (PSFs), including the generalized-cubic and squared-cubic phase mask wavefront encoded (WFE) PSFs, shown to reduce the impact of sample-induced spherical aberration in fluorescence microscopy. This investigation validates dynamic experimental parameter variation of these WFE-PSFs. We find that particular design parameter bounds exist, within which the divergence of computed and experimental WFE-PSFs is of the same order of magnitude as that of computed and experimental conventional PSFs, such that model-based approaches for solving the inverse imaging problem can be applied to a wide range of SLM-WFE systems. Interferometric measurements were obtained to evaluate the SLM implementation of the numeric mask. Agreement between experiment and theory in terms of a wrapped phase, 0-2π, validates the phase mask implementation and allows characterization of the SLM response. These measurements substantiate experimental practice of computational-optical microscope imaging with an SLM-engineered PSF.

  17. Characterization of ion-assisted induced absorption in A-Si thin-films used for multivariate optical computing

    NASA Astrophysics Data System (ADS)

    Nayak, Aditya B.; Price, James M.; Dai, Bin; Perkins, David; Chen, Ding Ding; Jones, Christopher M.

    2015-06-01

    Multivariate optical computing (MOC), an optical sensing technique for analog calculation, allows direct and robust measurement of chemical and physical properties of complex fluid samples in high-pressure/high-temperature (HP/HT) downhole environments. The core of this MOC technology is the integrated computational element (ICE), an optical element with a wavelength-dependent transmission spectrum designed to allow the detector to respond sensitively and specifically to the analytes of interest. A key differentiator of this technology is it uses all of the information present in the broadband optical spectrum to determine the proportion of the analyte present in a complex fluid mixture. The detection methodology is photometric in nature; therefore, this technology does not require a spectrometer to measure and record a spectrum or a computer to perform calculations on the recorded optical spectrum. The integrated computational element is a thin-film optical element with a specific optical response function designed for each analyte. The optical response function is achieved by fabricating alternating layers of high-index (a-Si) and low-index (SiO2) thin films onto a transparent substrate (BK7 glass) using traditional thin-film manufacturing processes (e.g., ion-assisted e-beam vacuum deposition). A proprietary software and process are used to control the thickness and material properties, including the optical constants of the materials during deposition to achieve the desired optical response function. The ion-assisted deposition is useful for controlling the densification of the film, stoichiometry, and material optical constants as well as to achieve high deposition growth rates and moisture-stable films. However, the ion-source can induce undesirable absorption in the film; and subsequently, modify the optical constants of the material during the ramp-up and stabilization period of the e-gun and ion-source, respectively. This paper characterizes the unwanted

  18. Summaries of Papers Presented at the Optical Computing Topical Meeting Held in Salt Lake City, Utah on 27 February thru 1 March 1989

    DTIC Science & Technology

    1989-12-31

    Microcavity and Optical Com. WA DIGITAL OPTICAL COMPUTING: 1 puting, C. Godsalve, E. Abraham, Heriot-Watt J., U.K. Char- John A. Neff, DuPont Corporation ...Kobayashi SONY Corporation Tokyo, 100-31, Japan Optical memory disks have been developed in recent years as mass storage media for audio, video, and...Technology Corporation MCC has been looking at the use of optics in computing syste’ 1s as a means to overcome barriers which are inadequately addressed by

  19. FOURTH SEMINAR TO THE MEMORY OF D.N. KLYSHKO: Quantum memory and quantum computations in the optical subradiance regime

    NASA Astrophysics Data System (ADS)

    Kalachev, A. A.; Samartsev, V. V.

    2005-08-01

    The possibilities of creation and manipulation of subradiant states in an extended atomic system by coherent 2π pulses are analysed. It is shown that excitation of the atomic system to collective subradiant states eliminates the superradiant broadening of the resonance line in quantum optical memory devices. The scheme of a nonlinear sign-shift two-qubit gate is proposed, which can be used in optical quantum computers.

  20. Development of a Computer-Controlled Polishing Process for X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Khan, Gufran S.; Gubarev, Mikhail; Arnold, William; Ramsey, Brian

    2009-01-01

    The future X-ray observatory missions require grazing-incidence x-ray optics with angular resolution of < 5 arcsec half-power diameter. The achievable resolution depends ultimately on the quality of polished mandrels from which the shells are replicated. With an aim to fabricate better shells, and reduce the cost/time of mandrel production, a computer-controlled polishing machine is developed for deterministic and localized polishing of mandrels. Cylindrical polishing software is also developed that predicts the surface residual errors under a given set of operating parameters and lap configuration. Design considerations of the polishing lap are discussed and the effects of nonconformance of the lap and the mandrel are presented.

  1. Modeling of edge effect in subaperture tool influence functions of computer controlled optical surfacing.

    PubMed

    Wan, Songlin; Zhang, Xiangchao; He, Xiaoying; Xu, Min

    2016-12-20

    Computer controlled optical surfacing requires an accurate tool influence function (TIF) for reliable path planning and deterministic fabrication. Near the edge of the workpieces, the TIF has a nonlinear removal behavior, which will cause a severe edge-roll phenomenon. In the present paper, a new edge pressure model is developed based on the finite element analysis results. The model is represented as the product of a basic pressure function and a correcting function. The basic pressure distribution is calculated according to the surface shape of the polishing pad, and the correcting function is used to compensate the errors caused by the edge effect. Practical experimental results demonstrate that the new model can accurately predict the edge TIFs with different overhang ratios. The relative error of the new edge model can be reduced to 15%.

  2. Simulation of radiation effects on three-dimensional computer optical memories

    NASA Technical Reports Server (NTRS)

    Moscovitch, M.; Emfietzoglou, D.

    1997-01-01

    A model was developed to simulate the effects of heavy charged-particle (HCP) radiation on the information stored in three-dimensional computer optical memories. The model is based on (i) the HCP track radial dose distribution, (ii) the spatial and temporal distribution of temperature in the track, (iii) the matrix-specific radiation-induced changes that will affect the response, and (iv) the kinetics of transition of photochromic molecules from the colored to the colorless isomeric form (bit flip). It is shown that information stored in a volume of several nanometers radius around the particle's track axis may be lost. The magnitude of the effect is dependent on the particle's track structure.

  3. Cryptanalysis and security enhancement of optical cryptography based on computational ghost imaging

    NASA Astrophysics Data System (ADS)

    Yuan, Sheng; Yao, Jianbin; Liu, Xuemei; Zhou, Xin; Li, Zhongyang

    2016-04-01

    Optical cryptography based on computational ghost imaging (CGI) has attracted much attention of researchers because it encrypts plaintext into a random intensity vector rather than complexed-valued function. This promising feature of the CGI-based cryptography reduces the amount of data to be transmitted and stored and therefore brings convenience in practice. However, we find that this cryptography is vulnerable to chosen-plaintext attack because of the linear relationship between the input and output of the encryption system, and three feasible strategies are proposed to break it in this paper. Even though a large number of plaintexts need to be chosen in these attack methods, it means that this cryptography still exists security risks. To avoid these attacks, a security enhancement method utilizing an invertible matrix modulation is further discussed and the feasibility is verified by numerical simulations.

  4. Computer generated hologram null test of a freeform optical surface with rectangular aperture

    NASA Astrophysics Data System (ADS)

    Su, Ping; Ma, Jianshe; Tan, Qiaofeng; Kang, Guoguo; Liu, Yi; Jin, Guofan

    2012-02-01

    In null computed generated hologram (CGH) test of optical elements, fitting method is needed in null CGH design to generate continuous phase function from the ray-traced discrete phase data. The null CGH for freeform testing usually has a deformed aperture and a high order phase function, because of the aberrations introduced by freeform wavefront propagation. With traditional Zernike polynomial fitting method, selection of an orthogonal basis set and choosing number of terms are needed before fitting. Zernike polynomial fitting method is not suitable in null CGH design for freeform testing; a novel CGH design method with cubic B-spline interpolation is developed. For a freeform surface with 18×18 mm2 rectangular aperture and 630 μm peak-to-valley undulation, the null CGH with a curved rectangular aperture is designed by using the method proposed. Simulation and experimental results proved the feasibility of the novel CGH design method.

  5. Edge control in a computer controlled optical surfacing process using a heterocercal tool influence function.

    PubMed

    Hu, Haixiang; Zhang, Xin; Ford, Virginia; Luo, Xiao; Qi, Erhui; Zeng, Xuefeng; Zhang, Xuejun

    2016-11-14

    Edge effect is regarded as one of the most difficult technical issues in a computer controlled optical surfacing (CCOS) process. Traditional opticians have to even up the consequences of the two following cases. Operating CCOS in a large overhang condition affects the accuracy of material removal, while in a small overhang condition, it achieves a more accurate performance, but leaves a narrow rolled-up edge, which takes time and effort to remove. In order to control the edge residuals in the latter case, we present a new concept of the 'heterocercal' tool influence function (TIF). Generated from compound motion equipment, this type of TIF can 'transfer' the material removal from the inner place to the edge, meanwhile maintaining the high accuracy and efficiency of CCOS. We call it the 'heterocercal' TIF, because of the inspiration from the heterocercal tails of sharks, whose upper lobe provides most of the explosive power. The heterocercal TIF was theoretically analyzed, and physically realized in CCOS facilities. Experimental and simulation results showed good agreement. It enables significant control of the edge effect and convergence of entire surface errors in large tool-to-mirror size-ratio conditions. This improvement will largely help manufacturing efficiency in some extremely large optical system projects, like the tertiary mirror of the Thirty Meter Telescope.

  6. Detecting microvascular changes in the mouse spleen using optical computed tomography.

    PubMed

    McErlean, Ciara M; Boult, Jessica K R; Collins, David J; Leach, Martin O; Robinson, Simon P; Doran, Simon J

    2015-09-01

    Methods of monitoring drug toxicity in off-target organs are very important in the development of effective and safe drugs. Standard 2-D techniques, such as histology, are prone to sampling errors and can miss important information. We demonstrate a novel application of optical computed tomography (CT) imaging to quantitatively assess, in 3-D, the response of adult murine spleen to off-target drug toxicity induced by treatment with the vascular disrupting agent ZD6126. Reconstructed images from optical CT scans sensitive to haemoglobin absorption reveal detailed, high-contrast 3-D maps of splenic structure and microvasculature. A significant difference in total splenic volume was found between vehicle and ZD6126-treated cohorts, with mean volumes of 61±3mm(3) and 44±3mm(3) respectively (both n=3, p=0.05). Textural statistics for each sample were calculated using grey-level co-occurrence matrices (GLCMs). Standard 2-D GLCM analysis was found to be slice-dependent while 3-D GLCM contrast and homogeneity analysis resulted in separation of the vehicle and ZD6126-treated cohorts over a range of length scales.

  7. Applications of computer-generated holograms for interferometric measurement of large aspheric optics

    NASA Astrophysics Data System (ADS)

    Burge, James H.

    1995-08-01

    Interferometric optical testing using computer-generated holograms (CGH's) has proven to give highly accurate measurements of aspheric surfaces. New applications of CGH interferometry were developed to support the fabrication of the large, steep mirrors required by the next generation ground-based telescopes. A new test to certify null correctors was designed and implemented that uses small CGH's fabricated onto flat surfaces. This test solves the difficult problem of verifying the accuracy of the null correctors that are used for measuring primary mirrors. Several new techniques for hologram fabrication have been explored for this application. A second new use of CGH's was developed for measuring convex secondary mirrors using test plates with holograms fabricated onto concave spherical reference surfaces. This test provides efficient and accurate measurement of large aspheric convex mirrors. A polar coordinate laser writing machine was built for fabricating these patterns onto curved optical surfaces up to 1.8 meters in diameter and as fast as f/1. These powerful new techniques have been implemented and optimized at the Steward Observatory Mirror Laboratory to guide mirror polishing for large telescope projects. They can also be readily applied for measuring small aspheres to high accuracy.

  8. Field applications of stand-off sensing using visible/NIR multivariate optical computing

    NASA Astrophysics Data System (ADS)

    Eastwood, DeLyle; Soyemi, Olusola O.; Karunamuni, Jeevanandra; Zhang, Lixia; Li, Hongli; Myrick, Michael L.

    2001-02-01

    12 A novel multivariate visible/NIR optical computing approach applicable to standoff sensing will be demonstrated with porphyrin mixtures as examples. The ultimate goal is to develop environmental or counter-terrorism sensors for chemicals such as organophosphorus (OP) pesticides or chemical warfare simulants in the near infrared spectral region. The mathematical operation that characterizes prediction of properties via regression from optical spectra is a calculation of inner products between the spectrum and the pre-determined regression vector. The result is scaled appropriately and offset to correspond to the basis from which the regression vector is derived. The process involves collecting spectroscopic data and synthesizing a multivariate vector using a pattern recognition method. Then, an interference coating is designed that reproduces the pattern of the multivariate vector in its transmission or reflection spectrum, and appropriate interference filters are fabricated. High and low refractive index materials such as Nb2O5 and SiO2 are excellent choices for the visible and near infrared regions. The proof of concept has now been established for this system in the visible and will later be extended to chemicals such as OP compounds in the near and mid-infrared.

  9. Computer-aided diagnosis of rheumatoid arthritis with optical tomography, Part 2: image classification.

    PubMed

    Montejo, Ludguier D; Jia, Jingfei; Kim, Hyun K; Netz, Uwe J; Blaschke, Sabine; Müller, Gerhard A; Hielscher, Andreas H

    2013-07-01

    This is the second part of a two-part paper on the application of computer-aided diagnosis to diffuse optical tomography (DOT) for diagnosing rheumatoid arthritis (RA). A comprehensive analysis of techniques for the classification of DOT images of proximal interphalangeal joints of subjects with and without RA is presented. A method for extracting heuristic features from DOT images was presented in Part 1. The ability of five classification algorithms to accurately label each DOT image as belonging to a subject with or without RA is analyzed here. The algorithms of interest are the k-nearest-neighbors, linear and quadratic discriminant analysis, self-organizing maps, and support vector machines (SVM). With a polynomial SVM classifier, we achieve 100.0% sensitivity and 97.8% specificity. Lower bounds for these results (at 95.0% confidence level) are 96.4% and 93.8%, respectively. Image features most predictive of RA are from the spatial variation of optical properties and the absolute range in feature values. The optimal classifiers are low-dimensional combinations (<7 features). These results underscore the high potential for DOT to become a clinically useful diagnostic tool and warrant larger prospective clinical trials to conclusively demonstrate the ultimate clinical utility of this approach.

  10. Single Layer Bismuth Iodide: Computational Exploration of Structural, Electrical, Mechanical and Optical Properties.

    PubMed

    Ma, Fengxian; Zhou, Mei; Jiao, Yalong; Gao, Guoping; Gu, Yuantong; Bilic, Ante; Chen, Zhongfang; Du, Aijun

    2015-12-02

    Layered graphitic materials exhibit new intriguing electronic structure and the search for new types of two-dimensional (2D) monolayer is of importance for the fabrication of next generation miniature electronic and optoelectronic devices. By means of density functional theory (DFT) computations, we investigated in detail the structural, electronic, mechanical and optical properties of the single-layer bismuth iodide (BiI3) nanosheet. Monolayer BiI3 is dynamically stable as confirmed by the computed phonon spectrum. The cleavage energy (Ecl) and interlayer coupling strength of bulk BiI3 are comparable to the experimental values of graphite, which indicates that the exfoliation of BiI3 is highly feasible. The obtained stress-strain curve shows that the BiI3 nanosheet is a brittle material with a breaking strain of 13%. The BiI3 monolayer has an indirect band gap of 1.57 eV with spin orbit coupling (SOC), indicating its potential application for solar cells. Furthermore, the band gap of BiI3 monolayer can be modulated by biaxial strain. Most interestingly, interfacing electrically active graphene with monolayer BiI3 nanosheet leads to enhanced light absorption compared to that in pure monolayer BiI3 nanosheet, highlighting its great potential applications in photonics and photovoltaic solar cells.

  11. Single Layer Bismuth Iodide: Computational Exploration of Structural, Electrical, Mechanical and Optical Properties

    NASA Astrophysics Data System (ADS)

    Ma, Fengxian; Zhou, Mei; Jiao, Yalong; Gao, Guoping; Gu, Yuantong; Bilic, Ante; Chen, Zhongfang; Du, Aijun

    2015-12-01

    Layered graphitic materials exhibit new intriguing electronic structure and the search for new types of two-dimensional (2D) monolayer is of importance for the fabrication of next generation miniature electronic and optoelectronic devices. By means of density functional theory (DFT) computations, we investigated in detail the structural, electronic, mechanical and optical properties of the single-layer bismuth iodide (BiI3) nanosheet. Monolayer BiI3 is dynamically stable as confirmed by the computed phonon spectrum. The cleavage energy (Ecl) and interlayer coupling strength of bulk BiI3 are comparable to the experimental values of graphite, which indicates that the exfoliation of BiI3 is highly feasible. The obtained stress-strain curve shows that the BiI3 nanosheet is a brittle material with a breaking strain of 13%. The BiI3 monolayer has an indirect band gap of 1.57 eV with spin orbit coupling (SOC), indicating its potential application for solar cells. Furthermore, the band gap of BiI3 monolayer can be modulated by biaxial strain. Most interestingly, interfacing electrically active graphene with monolayer BiI3 nanosheet leads to enhanced light absorption compared to that in pure monolayer BiI3 nanosheet, highlighting its great potential applications in photonics and photovoltaic solar cells.

  12. Optical diagnostics of a single evaporating droplet using fast parallel computing on graphics processing units

    NASA Astrophysics Data System (ADS)

    Jakubczyk, D.; Migacz, S.; Derkachov, G.; Woźniak, M.; Archer, J.; Kolwas, K.

    2016-09-01

    We report on the first application of the graphics processing units (GPUs) accelerated computing technology to improve performance of numerical methods used for the optical characterization of evaporating microdroplets. Single microdroplets of various liquids with different volatility and molecular weight (glycerine, glycols, water, etc.), as well as mixtures of liquids and diverse suspensions evaporate inside the electrodynamic trap under the chosen temperature and composition of atmosphere. The series of scattering patterns recorded from the evaporating microdroplets are processed by fitting complete Mie theory predictions with gradientless lookup table method. We showed that computations on GPUs can be effectively applied to inverse scattering problems. In particular, our technique accelerated calculations of the Mie scattering theory on a single-core processor in a Matlab environment over 800 times and almost 100 times comparing to the corresponding code in C language. Additionally, we overcame problems of the time-consuming data post-processing when some of the parameters (particularly the refractive index) of an investigated liquid are uncertain. Our program allows us to track the parameters characterizing the evaporating droplet nearly simultaneously with the progress of evaporation.

  13. The coefficient of error of optical fractionator population size estimates: a computer simulation comparing three estimators.

    PubMed

    Glaser, E M; Wilson, P D

    1998-11-01

    The optical fractionator is a design-based two-stage systematic sampling method that is used to estimate the number of cells in a specified region of an organ when the population is too large to count exhaustively. The fractionator counts the cells found in optical disectors that have been systematically sampled in serial sections. Heretofore, evaluations of optical fractionator performance have been made by performing tests on actual tissue sections, but it is difficult to evaluate the coefficient of error (CE), i.e. the precision of a population size estimate, by using biological tissue samples because they do not permit a comparison of an estimated CE with the true CE. However, computer simulation does permit making such comparisons while avoiding the observational biases inherent in working with biological tissue. This study is the first instance in which computer simulation has been applied to population size estimation by the optical fractionator. We used computer simulation to evaluate the performance of three CE estimators. The estimated CEs were evaluated in tests of three types of non-random cell population distribution and one random cell population distribution. The non-random population distributions varied by differences in 'intensity', i.e. the expected cell counts per disector, according to both section and disector location within the section. Two distributions were sinusoidal and one was linearly increasing; in all three there was a six-fold difference between the high and low intensities. The sinusoidal distributions produced either a peak or a depression of cell intensity at the centre of the simulated region. The linear cell intensity gradually increased from the beginning to the end of the region that contained the cells. The random population distribution had a constant intensity over the region. A 'test condition' was defined by its population distribution, the period between consecutive sampled sections and the spacing between consecutive

  14. Computational-optical microscopy for 3D biological imaging beyond the diffraction limit

    NASA Astrophysics Data System (ADS)

    Grover, Ginni

    In recent years, super-resolution imaging has become an important fluorescent microscopy tool. It has enabled imaging of structures smaller than the optical diffraction limit with resolution less than 50 nm. Extension to high-resolution volume imaging has been achieved by integration with various optical techniques. In this thesis, development of a fluorescent microscope to enable high resolution, extended depth, three dimensional (3D) imaging is discussed; which is achieved by integration of computational methods with optical systems. In the first part of the thesis, point spread function (PSF) engineering for volume imaging is discussed. A class of PSFs, referred to as double-helix (DH) PSFs, is generated. The PSFs exhibit two focused spots in the image plane which rotate about the optical axis, encoding depth in rotation of the image. These PSFs extend the depth-of-field up to a factor of ˜5. Precision performance of the DH-PSFs, based on an information theoretical analysis, is compared with other 3D methods with conclusion that the DH-PSFs provide the best precision and the longest depth-of-field. Out of various possible DH-PSFs, a suitable PSF is obtained for super-resolution microscopy. The DH-PSFs are implemented in imaging systems, such as a microscope, with a special phase modulation at the pupil plane. Surface-relief elements which are polarization-insensitive and ˜90% light efficient are developed for phase modulation. The photon-efficient DH-PSF microscopes thus developed are used, along with optimal position estimation algorithms, for tracking and super-resolution imaging in 3D. Imaging at depths-of-field of up to 2.5 microm is achieved without focus scanning. Microtubules were imaged with 3D resolution of (6, 9, 39) nm, which is in close agreement with the theoretical limit. A quantitative study of co-localization of two proteins in volume was conducted in live bacteria. In the last part of the thesis practical aspects of the DH-PSF microscope are

  15. Experimental, computational, and analytical techniques for diagnosing breast cancer using optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Palmer, Gregory M.

    This dissertation presents the results of an investigation into experimental, computational, and analytical methodologies for diagnosing breast cancer using fluorescence and diffuse reflectance spectroscopy. First, the optimal experimental methodology for tissue biopsy studies was determined using an animal study. It was found that the use of freshly excised tissue samples preserved the original spectral line shape and magnitude of the fluorescence and diffuse reflectance. Having established the optimal experimental methodology, a clinical study investigating the use of fluorescence and diffuse reflectance spectroscopy for the diagnosis of breast cancer was undertaken. In addition, Monte Carlo-based models of diffuse reflectance and fluorescence were developed and validated to interpret these data. These models enable the extraction of physically meaningful information from the measured spectra, including absorber concentrations, and scattering and intrinsic fluorescence properties. The model was applied to the measured spectra, and using a support vector machine classification algorithm based on physical features extracted from the diffuse reflectance spectra, it was found that breast cancer could be diagnosed with a cross-validated sensitivity and specificity of 82% and 92%, respectively, which are substantially better than that obtained using a conventional, empirical algorithm. It was found that malignant tissues had lower hemoglobin oxygen saturation, were more scattering, and had lower beta-carotene concentration, relative to the non-malignant tissues. It was also found that the fluorescence model could successfully extract the intrinsic fluorescence line shape from tissue samples. One limitation of the previous study is that a priori knowledge of the tissue's absorbers and scatterers is required. To address this limitation, and to improve upon the method with which fiber optic probes are designed, an alternate approach was developed. This method used a

  16. A first principle approach using Maximally Localized Wannier Functions for computing and understanding elasto-optic reponse

    NASA Astrophysics Data System (ADS)

    Liang, Xin; Ismail-Beigi, Sohrab

    Strain-induced changes of optical properties are of use in the design and functioning of devices that couple photons and phonons. The elasto-optic (or photo-elastic) effect describes a general materials property where strain induces a change in the dielectric tensor. Despite a number of experimental and computational works, it is fair to say that a basic physical understanding of the effect and its materials dependence is lacking: e.g., we know of no materials design rule for enhancing or suppressing elasto-optic response. Based on our previous work, we find that a real space representation, as opposed to a k-space description, is a promising way to understand this effect. We have finished the development of a method of computing the dielectric and elasto-optic tensors using Maximally Localized Wannier Functions (MLWFs). By analyzing responses to uniaxial strain, we find that both tensors respond in a localized manner to the perturbation: the dominant optical transitions are between local electronic states on nearby bonds. We describe the method, the resulting physical picture and computed results for semiconductors. This work is supported by the National Science Foundation through Grant NSF DMR-1104974.

  17. A 250-Mbit/s ring local computer network using 1.3-microns single-mode optical fibers

    NASA Technical Reports Server (NTRS)

    Eng, S. T.; Tell, R.; Andersson, T.; Eng, B.

    1985-01-01

    A 250-Mbit/s three-station fiber-optic ring local computer network was built and successfully demonstrated. A conventional token protocol was employed for bus arbitration to maximize the bus efficiency under high loading conditions, and a non-return-to-zero (NRS) data encoding format was selected for simplicity and maximum utilization of the ECL-circuit bandwidth.

  18. Recent advances in the application of computer-controlled optical finishing to produce very high-quality transmissive optical elements and windows

    NASA Astrophysics Data System (ADS)

    Askinazi, Joel; Estrin, Aleksandr; Green, Alan; Turner, Aaron N.

    2003-09-01

    Large aperture (20-inch diameter) sapphire optical windows have been identified as a key element of new and/or upgraded airborne electro-optical systems. These windows typically require a transmitted wave front error of much less than 0.1 waves rms @ 0.63 microns over 7 inch diameter sub-apertures. Large aperture (14-inch diameter by 4-inch thick) sapphire substrates have also been identified as a key optical element of the Laser Interferometer Gravitational Wave Observatory (LIGO). This project is under joint development by the California Institute of Technology (Caltech) and the Massachusetts Institute of Technology under cooperative agreement with the National Science foundation (NSF). These substrates are required to have a transmitted wave front error of 20 nm (0.032 waves) rms @ 0.63 microns over 6-inch sub-apertures with a desired error of 10 nm (0.016 waves) rms. Owing to the spatial variations in the optical index of refraction potentially anticipated within 20-inch diameter sapphire, thin (0.25 - 0.5-inch) window substrates, as well as within the 14-inch diameter by 4-inch thick substrates for the LIGO application, our experience tells us that the required transmitted wave front errors can not be achieved with standard optical finishing techniques as they can not readily compensate for errors introduced by inherent material characteristics. Computer controlled optical finishing has been identified as a key technology likely required to enable achievement of the required transmitted wave front errors. Goodrich has developed this technology and has previously applied it to finish high quality sapphire optical windows with a range of aperture sizes from 4-inch to 13-inch to achieve transmitted wavefront errors comparable to these new requirements. This paper addresses successful recent developments and accomplishments in the application of this optical finishing technology to sequentially larger aperture and thicker sapphire windows to achieve the

  19. Multiphonon scattering of light with direct transitions between optical modes in uniaxial single crystals and its application to an all-optical computing

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Alexandre S.; Tepichin Rodriguez, Eduardo; Aguirre Lopez, Arturo

    2004-11-01

    A specific case of a multi-phonon non-collinear light scattering in optically uniaxial media is presented. Compared to our previous studies, an innovation lies in the fact that now we consider passing just the quartet of incident light beams through a single crystal that is perturbed by the triplet of coherent acoustic waves. The exact and closed analytical model for describing this strongly nonlinear phenomenon is developed. In fact, specially designed regime of a four-order light scattering whit direct coupling of all the light modes, when transitions of four input light beams into four output light modes are allowed and electronically controlled, is examined. The feasibility of applying such an effect to an all-optical computing and performing an all-optical adder is analyzed.

  20. Acousto-optic Bragg diffraction in a LiNbO3 channel-planar composite waveguide with application to optical computing

    NASA Astrophysics Data System (ADS)

    Tsai, C. S.; Zang, D. Y.; Le, P.

    1985-09-01

    Successful experimentation on acousto-optic Bragg diffraction in a LiNbO3 composite waveguide that consists of an array of parallel but uncoupled channel waveguides directly extended to a single-mode planar waveguide and a titanium-indiffused proton-exchanged (TIPE) microlens array is reported for the first time. A channel-waveguide array, a planar waveguide, a linear TIPE microlens array, a 500-MHz surface acoustic wave transducer, and an integrating lens have all been integrated in a substrate size of 0.2 x 1.0 x 2.0 cm to form an integrated acousto-optic Bragg modulator that should find a variety of applications in optical computing, signal processing, and communications. The resulting modulator module has been utilized to perform matrix-vector multiplication.

  1. Impairments Computation for Routing Purposes in a Transparent-Access Optical Network Based on Optical CDMA and WDM

    NASA Astrophysics Data System (ADS)

    Musa, Ahmed

    2016-06-01

    Optical access networks are becoming more widespread and the use of multiple services might require a transparent optical network (TON). Multiplexing and privacy could benefit from the combination of wavelength division multiplexing (WDM) and optical coding (OC) and wavelength conversion in optical switches. The routing process needs to be cognizant of different resource types and characteristics such as fiber types, fiber linear impairments such as attenuation, dispersion, etc. as well as fiber nonlinear impairments such as four-wave mixing, cross-phase modulation, etc. Other types of impairments, generated by optical nodes or photonic switches, also affect the signal quality (Q) or the optical signal to noise ratio (OSNR), which is related to the bit error rate (BER). Therefore, both link and switch impairments must be addressed and somehow incorporated into the routing algorithm. However, it is not practical to fully integrate all photonic-specific attributes in the routing process. In this study, new routing parameters and constraints are defined that reflect the distinct characteristics of photonic networking. These constraints are applied to the design phase of TON and expressed as a cost or metric form that will be used in the network routing algorithm.

  2. Optical computed tomography utilizing a rotating mirror and Fresnel lenses: operating principles and preliminary results

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Wuu, Cheng-Shie

    2013-02-01

    The performance of a fast optical computed tomography (CT) scanner based on a point laser source, a small area photodiode detector, and two optical-grade Fresnel lenses is evaluated. The OCTOPUS™-10× optical CT scanner (MGS Research Inc., Madison, CT) is an upgrade of the OCTOPUS™ research scanner with improved design for faster motion of the laser beam and faster data acquisition process. The motion of the laser beam in the new configuration is driven by the rotational motion of a scanning mirror. The center of the scanning mirror and the center of the photodiode detector are adjusted to be on the focal points of two coaxial Fresnel lenses. A glass water tank is placed between the two Fresnel lenses to house gel phantoms and matching liquids. The laser beam scans over the water tank in parallel beam geometry for projection data as the scanning mirror rotates at a frequency faster than 0.1 s per circle. Signal sampling is performed independently of the motion of the scanning mirror, to reduce the processing time for the synchronization of the stepper motors and the data acquisition board. An in-house developed reference image normalization mechanism is added to the image reconstruction program to correct the non-uniform light transmitting property of the Fresnel lenses. Technical issues with regard to the new design of the scanner are addressed, including projection data extraction from raw data samples, non-uniform pixel averaging and reference image normalization. To evaluate the dosimetric accuracy of the scanner, the reconstructed images from a 16 MeV, 6 cm × 6 cm electron field irradiation were compared with those from the Eclipse treatment planning system (Varian Corporation, Palo Alto, CA). The spatial resolution of the scanner is demonstrated to be of sub-millimeter accuracy. The effectiveness of the reference normalization method for correcting the non-uniform light transmitting property of the Fresnel lenses is analyzed. A sub-millimeter accuracy of

  3. Fast computation of diffuse reflectance in optical coherence tomography using an importance sampling-based Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Lima, Ivan T., Jr.; Kalra, Anshul; Hernández-Figueroa, Hugo E.; Sherif, Sherif S.

    2012-03-01

    Computer simulations of light transport in multi-layered turbid media are an effective way to theoretically investigate light transport in tissue, which can be applied to the analysis, design and optimization of optical coherence tomography (OCT) systems. We present a computationally efficient method to calculate the diffuse reflectance due to ballistic and quasi-ballistic components of photons scattered in turbid media, which represents the signal in optical coherence tomography systems. Our importance sampling based Monte Carlo method enables the calculation of the OCT signal with less than one hundredth of the computational time required by the conventional Monte Carlo method. It also does not produce a systematic bias in the statistical result that is typically observed in existing methods to speed up Monte Carlo simulations of light transport in tissue. This method can be used to assess and optimize the performance of existing OCT systems, and it can also be used to design novel OCT systems.

  4. Observation of the pulp horn by swept source optical coherence tomography and cone beam computed tomography

    NASA Astrophysics Data System (ADS)

    Iino, Yoshiko; Yoshioka, Toshihiko; Hanada, Takahiro; Ebihara, Arata; Sunakawa, Mitsuhiro; Sumi, Yasunori; Suda, Hideaki

    2015-02-01

    Cone-beam computed tomography (CBCT) is one of the most useful diagnostic techniques in dentistry but it involves ionizing radiation, while swept source optical coherence tomography (SS-OCT) has been introduced recently as a nondestructive, real-time, high resolution imaging technique using low-coherence interferometry, which involves no ionizing radiation. The purpose of this study was to evaluate the ability of SS-OCT to detect the pulp horn (PH) in comparison with that of CBCT. Ten extracted human mandibular molars were used. After horizontally removing a half of the tooth crown, the distance from the cut dentin surface to PH was measured using microfocus computed tomography (Micro CT) (SL) as the gold standard, by CBCT (CL) and by SS-OCT (OL). In the SS-OCT images, only when PH was observed beneath the overlying dentin, the distance from the cut dentin surface to PH was recorded. If the pulp was exposed, it was defined as pulp exposure (PE). The results obtained by the above three methods were statistically analyzed by Spearman's rank correlation coefficient at a significance level of p < 0.01. SS-OCT detected the presence of PH when the distance from the cut dentin surface to PH determined by SL was 2.33 mm or less. Strong correlations of the measured values were found between SL and CL (r=0.87), SL and OL (r=0.96), and CL and OL (r=0.86). The results showed that SS-OCT images correlated closely with CBCT images, suggesting that SS-OCT can be a useful tool for the detection of PH.

  5. Computational Fluid Dynamics (CFD) Analysis Of Optical Payload For Lasercomm Science (OPALS) sealed enclosure module

    NASA Technical Reports Server (NTRS)

    Anderson, Kevin R.; Zayas, Daniel; Turner, Daniel

    2012-01-01

    Computational Fluid Dynamics (CFD) using the commercial CFD package CFDesign has been performed at NASA Jet Propulsion Laboratory (JPL) California Institute of Technology (Caltech) in support of the Phaeton Early Career Hire Program's Optical Payload for Lasercomm Science (OPALS) mission. The OPALS project is one which involves an International Space Station payload that will be using forced convection cooling in a hermetically sealed enclosure at 1 atm of air to cool "off-the-shelf" vendor electronics. The CFD analysis was used to characterize the thermal and fluid flow environment within a complicated labyrinth of electronics boards, fans, instrumentation, harnessing, ductwork and heat exchanger fins. The paradigm of iteratively using CAD/CAE tools and CFD was followed in order to determine the optimum flow geometry and heat sink configuration to yield operational convective film coefficients and temperature survivability limits for the electronics payload. Results from this current CFD analysis and correlation of the CFD model against thermal test data will be presented. Lessons learned and coupled thermal / flow modeling strategies will be shared in this paper.

  6. A doubly logarithmic communication algorithm for the Completely Connected Optical Communication Parallel Computer

    SciTech Connect

    Goldberg, L.A.; Jerrum, M.; Leighton, T.; Rao, S.

    1993-01-20

    In this paper we consider the problem of interprocessor communication on a Completely Connected Optical Communication Parallel Computer (OCPC). The particular problem we study is that of realizing an h-relation. In this problem, each processor has at most h messages to send and at most h messages to receive. It is clear that any 1-relation can be realized in one communication step on an OCPC. However, the best known p-processor OCPC algorithm for realizing an arbitrary h-relation for h > 1 requires {Theta}(h + log p) expected communication steps. (This algorithm is due to Valiant and is based on earlier work of Anderson and Miller.) Valiant`s algorithm is optimal only for h = {Omega}(log p) and it is an open question of Gereb-Graus and Tsantilas whether there is a faster algorithm for h = o(log p). In this paper we answer this question in the affirmative by presenting a {Theta} (h + log log p) communication step algorithm that realizes an arbitrary h-relation on a p-processor OCPC. We show that if h {le} log p then the failure probability can be made as small as p{sup -{alpha}} for any positive constant {alpha}.

  7. Computing the total atmospheric refraction for real-time optical imaging sensor simulation

    NASA Astrophysics Data System (ADS)

    Olson, Richard F.

    2015-05-01

    Fast and accurate computation of light path deviation due to atmospheric refraction is an important requirement for real-time simulation of optical imaging sensor systems. A large body of existing literature covers various methods for application of Snell's Law to the light path ray tracing problem. This paper provides a discussion of the adaptation to real time simulation of atmospheric refraction ray tracing techniques used in mid-1980's LOWTRAN releases. The refraction ray trace algorithm published in a LOWTRAN-6 technical report by Kneizys (et. al.) has been coded in MATLAB for development, and in C-language for simulation use. To this published algorithm we have added tuning parameters for variable path segment lengths, and extensions for Earth grazing and exoatmospheric "near Earth" ray paths. Model atmosphere properties used to exercise the refraction algorithm were obtained from tables published in another LOWTRAN-6 related report. The LOWTRAN-6 based refraction model is applicable to atmospheric propagation at wavelengths in the IR and visible bands of the electromagnetic spectrum. It has been used during the past two years by engineers at the U.S. Army Aviation and Missile Research, Development and Engineering Center (AMRDEC) in support of several advanced imaging sensor simulations. Recently, a faster (but sufficiently accurate) method using Gauss-Chebyshev Quadrature integration for evaluating the refraction integral was adopted.

  8. Error in the sampling area of an optical disdrometer: consequences in computing rain variables.

    PubMed

    Fraile, R; Castro, A; Fernández-Raga, M; Palencia, C; Calvo, A I

    2013-01-01

    The aim of this study is to improve the estimation of the characteristic uncertainties of optic disdrometers in an attempt to calculate the efficient sampling area according to the size of the drop and to study how this influences the computation of other parameters, taking into account that the real sampling area is always smaller than the nominal area. For large raindrops (a little over 6 mm), the effective sampling area may be half the area indicated by the manufacturer. The error committed in the sampling area is propagated to all the variables depending on this surface, such as the rain intensity and the reflectivity factor. Both variables tend to underestimate the real value if the sampling area is not corrected. For example, the rainfall intensity errors may be up to 50% for large drops, those slightly larger than 6 mm. The same occurs with reflectivity values, which may be up to twice the reflectivity calculated using the uncorrected constant sampling area. The Z-R relationships appear to have little dependence on the sampling area, because both variables depend on it the same way. These results were obtained by studying one particular rain event that occurred on April 16, 2006.

  9. Synthesis, crystal structure, conformational analysis, nonlinear optical property and computational study of novel pregnane derivatives

    NASA Astrophysics Data System (ADS)

    Singh, Ranvijay Pratap; kant, Rajni; Singh, Kuldeep; Sharma, Sonia; Sethi, Arun

    2015-09-01

    The molecular structure and detailed spectroscopic analysis of some novel newly synthesized pregnane derivatives have been performed using experimental techniques like 1H, 13C NMR, NOESY, FT-IR, UV-visible spectroscopy, mass spectrometry, crystallography, as well as theoretical calculations. The structure and stereochemistry of 3β-benzoyloxy 16α-methoxy pregn-5-ene-20-one (3) has been confirmed by single crystal X-ray diffraction, which crystallized in orthorhombic form having P212121 space group with unit cell parameters a = 6.395(5) Å, b = 19.872(17) Å, c = 19.898(16) Å and Z = 4. Quantum chemical calculations have been performed by density functional theory (DFT) using B3LYP functional and 6-31G (d,p) basis set. The electronic properties such as frontier orbitals and band gap energies have been calculated using time dependent density functional theory (TD-DFT). The strength and nature of weak intramolecular interactions have been studied by AIM approach. The vibrational wavenumbers have been calculated using DFT method and assigned with the help of potential energy distribution (PED). Global and local reactivity descriptors have been computed to predict reactivity and reactive sites in the molecule. First hyperpolarizability values have been calculated to describe the nonlinear optical (NLO) property of the synthesized compounds. Molecular electrostatic potential (MEP) analysis has also been carried out.

  10. Computational model of bladder tissue based on its measured optical properties

    NASA Astrophysics Data System (ADS)

    Rafailov, Ilya E.; Dremin, Victor V.; Litvinova, Karina S.; Dunaev, Andrey V.; Sokolovski, Sergei G.; Rafailov, Edik U.

    2016-02-01

    Urinary bladder diseases are a common problem throughout the world and often difficult to accurately diagnose. Furthermore, they pose a heavy financial burden on health services. Urinary bladder tissue from male pigs was spectrophotometrically measured and the resulting data used to calculate the absorption, transmission, and reflectance parameters, along with the derived coefficients of scattering and absorption. These were employed to create a "generic" computational bladder model based on optical properties, simulating the propagation of photons through the tissue at different wavelengths. Using the Monte-Carlo method and fluorescence spectra of UV and blue excited wavelength, diagnostically important biomarkers were modeled. Additionally, the multifunctional noninvasive diagnostics system "LAKK-M" was used to gather fluorescence data to further provide essential comparisons. The ultimate goal of the study was to successfully simulate the effects of varying excited radiation wavelengths on bladder tissue to determine the effectiveness of photonics diagnostic devices. With increased accuracy, this model could be used to reliably aid in differentiating healthy and pathological tissues within the bladder and potentially other hollow organs.

  11. Computational model of bladder tissue based on its measured optical properties.

    PubMed

    Rafailov, Ilya E; Dremin, Victor V; Litvinova, Karina S; Dunaev, Andrey V; Sokolovski, Sergei G; Rafailov, Edik U

    2016-02-01

    Urinary bladder diseases are a common problem throughout the world and often difficult to accurately diagnose. Furthermore, they pose a heavy financial burden on health services. Urinary bladder tissue from male pigs was spectrophotometrically measured and the resulting data used to calculate the absorption, transmission, and reflectance parameters, along with the derived coefficients of scattering and absorption. These were employed to create a "generic" computational bladder model based on optical properties, simulating the propagation of photons through the tissue at different wavelengths. Using the Monte-Carlo method and fluorescence spectra of UV and blue excited wavelength, diagnostically important biomarkers were modeled. Additionally, the multifunctional noninvasive diagnostics system "LAKK-M" was used to gather fluorescence data to further provide essential comparisons. The ultimate goal of the study was to successfully simulate the effects of varying excited radiation wavelengths on bladder tissue to determine the effectiveness of photonics diagnostic devices. With increased accuracy, this model could be used to reliably aid in differentiating healthy and pathological tissues within the bladder and potentially other hollow organs.

  12. Computer-aided diagnosis of rheumatoid arthritis with optical tomography, Part 1: feature extraction.

    PubMed

    Montejo, Ludguier D; Jia, Jingfei; Kim, Hyun K; Netz, Uwe J; Blaschke, Sabine; Müller, Gerhard A; Hielscher, Andreas H

    2013-07-01

    This is the first part of a two-part paper on the application of computer-aided diagnosis to diffuse optical tomography (DOT). An approach for extracting heuristic features from DOT images and a method for using these features to diagnose rheumatoid arthritis (RA) are presented. Feature extraction is the focus of Part 1, while the utility of five classification algorithms is evaluated in Part 2. The framework is validated on a set of 219 DOT images of proximal interphalangeal (PIP) joints. Overall, 594 features are extracted from the absorption and scattering images of each joint. Three major findings are deduced. First, DOT images of subjects with RA are statistically different (p<0.05) from images of subjects without RA for over 90% of the features investigated. Second, DOT images of subjects with RA that do not have detectable effusion, erosion, or synovitis (as determined by MRI and ultrasound) are statistically indistinguishable from DOT images of subjects with RA that do exhibit effusion, erosion, or synovitis. Thus, this subset of subjects may be diagnosed with RA from DOT images while they would go undetected by reviews of MRI or ultrasound images. Third, scattering coefficient images yield better one-dimensional classifiers. A total of three features yield a Youden index greater than 0.8. These findings suggest that DOT may be capable of distinguishing between PIP joints that are healthy and those affected by RA with or without effusion, erosion, or synovitis.

  13. All-optical switching with bacteriorhodopsin protein coated microcavities and its application to low power computing circuits

    NASA Astrophysics Data System (ADS)

    Roy, Sukhdev; Prasad, Mohit; Topolancik, Juraj; Vollmer, Frank

    2010-03-01

    We show all-optical switching of an input infrared laser beam at 1310 nm by controlling the photoinduced retinal isomerization to tune the resonances in a silica microsphere coated with three bacteriorhodopsin (BR) protein monolayers. The all-optical tunable resonant coupler re-routes the infrared beam between two tapered fibers in 50 μs using a low power (<200 μW) green (532 nm) and blue (405 nm) pump beams. The basic switching configuration has been used to design all-optical computing circuits, namely, half and full adder/subtractor, de-multiplexer, multiplexer, and an arithmetic unit. The design requires 2n-1 switches to realize n bit computation. The designs combine the exceptional sensitivities of BR and high-Q microcavities and the versatile tree architecture for realizing low power circuits and networks (approximately mW power budget). The combined advantages of high Q-factor, tunability, compactness, and low power control signals, with the flexibility of cascading switches to form circuits, and reversibility and reconfigurability to realize arithmetic and logic functions, makes the designs promising for practical applications. The designs are general and can be implemented (i) in both fiber-optic and integrated optic formats, (ii) with any other coated photosensitive material, or (iii) any externally controlled microresonator switch.

  14. Optical disk archiving using a personal computer: a solution to image storage problems in diagnostic imaging departments.

    PubMed

    Parkin, A; Norwood, H; Erdentug, A; Hall, A J

    1990-01-01

    The paper describes an approach to solving the problem of providing a large-capacity image archive for diagnostic imaging departments at reasonable cost. Optical disk stores, when fitted retrospectively to scanners, are very expensive and may not be compatible with existing computer hardware. We describe the use of an industry standard personal computer (PC) linked to a standard 5 1/4-in. optical disk drive as a 'stand-alone' image store. Image data are transferred from the scanner using 8-in. floppy disks, and these are read into the PC using an attached 8-in. floppy disk drive and then transferred to the optical disk. The patient details (patient name, ID, date, etc.) are entered into a database program held on the PC and these are used to generate a reference pointer to the optical disk file through which the data can be retrieved. Data retrieval involves entering the patient details into the data base and inserting a blank 8-in. floppy disk into the drive attached to the PC. A sector copy is then made from the optical disk to the 8-in. floppy disk, which can then be used at the viewing station at the scanner. The system is flexible since it can accept data from a variety of sources in any format; it is also low cost and operates independently of the scanner. The hardware is industry standard, ensuring low maintenance costs.

  15. Reliability of a Computer-Aided Manual Procedure for Segmenting Optical Coherence Tomography Scans

    PubMed Central

    Hood, Donald C.; Cho, Jungsuk; Raza, Ali S.; Dale, Elizabeth A.; Wang, Min

    2011-01-01

    Purpose To assess the within- and between-operator agreement of a computer-aided manual segmentation procedure for frequency-domain optical coherence tomography scans. Methods Four individuals (segmenters) used a computer-aided manual procedure to mark the borders defining the layers analyzed in glaucoma studies. After training, they segmented two sets of scans, an Assessment Set and a Test Set. Each set had scans from 10 patients with glaucoma and 10 healthy controls. Based on an analysis of the Assessment Set, a set of guidelines was written. The Test Set was segmented twice with a ≥1 month separation. Various measures were used to compare test and retest (within-segmenter) variability and between-segmenter variability including concordance correlations between layer borders and the mean across scans (n = 20) of the mean of absolute differences between local border locations of individual scans, MEAN{mean(ΔLBL)}. Results Within-segmenter reliability was good. The mean concordance correlations values for an individual segmenter and a particular border ranged from 0.999 ± 0.000 to 0.978 ± 0.084. The MEAN{mean(ΔLBL)} values ranged from 1.6 to 4.7 μm depending on border and segmenter. Similarly, between-segmenter agreement was good. The mean concordance correlations values for an individual segmenter and a particular border ranged from 0.999 ± 0.001 to 0.992 ± 0.023. The MEAN{mean(ΔLBL)} values ranged from 1.9 to 4.0 μm depending on border and segmenter. The signed and unsigned average positions were considerably smaller than the MEAN{mean(ΔLBL)} values for both within- and between-segmenter comparisons. Measures of within-segmenter variability were only slightly larger than those of between-segmenter variability. Conclusions When human segmenters are trained, the within- and between-segmenter reliability of manual border segmentation is quite good. When expressed as a percentage of retinal layer thickness, the results suggest that manual segmentation

  16. Looking for Speed!! Go Optical Ultra-Fast Photonic Logic Gates for the Future Optical Communication and Computing

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin; Frazier, Donald O.; Penn, Benjamin; Paley, Mark S.

    2003-01-01

    Recently, we developed two ultra-fast all-optical switches in the nanosecond and picosecond regimes. The picosecond switch is made of a polydiacetylene thin film coated on the interior wall of a hollow capillary of approximately 50 micron diameter by a photo-polymerization process. In the setup a picosecond Nd:YAG laser at 10 Hz and at 532 nm with a pulse duration of approximately 40 ps was sent collinearly along a cw He-Ne laser beam and both were waveguided through the hollow capillary. The setup functioned as an Exclusive OR gate. On the other hand, the material used in the nanosecond switch is a phthalocyanine thin film, deposited on a glass substrate by a vapor deposition technique. In the setup a nanosecond, 10 Hz, Nd:YAG laser of 8 ns pulse duration was sent collinearly along a cw He-Ne laser beam and both were wave-guided through the phthalocyanine thin film. The setup in this case functioned as an all-optical AND logic gate. The characteristic table of the ExOR gate in polydiacetylene film was attributed to an excited state absorption process, while that of the AND gate was attributed to a saturation process of the first excited state. Both mechanisms were thoroughly investigated theoretically and found to agree remarkably well with the experimental results. An all-optical inverter gate has been designed but has not yet been demonstrated. The combination of all these three gates form the foundation for building all the necessary gates needed to build a prototype of an all-optical system.

  17. Computer-aided alignment method of optical lens with high accuracy

    NASA Astrophysics Data System (ADS)

    Xing, Song; Hou, Xiao-hua; Zhang, Xue-min; Ji, Bin-dong

    2016-09-01

    With the development of space and aviation industry, the optical systems with high resolution and better imaging quality are required. According to the alignment technical process, the factors of every step which have big influence to the imaging quality are analyzed. It is detected that the micro-stress assembly of the optical unit and the high co-axial precision of the entire optical system are the two important factors which are supposed to determine how well the imaging quality of the optical system is; also the technical methods are discussed to ensure these two factors from the engineering view. The reflective interference testing method to measure the surface figure and the transitive interference testing method to measure the wave aberration of the optical unit are combined to ensure the micro-stress assembly of the optical unit, so it will not bring astigmatism to the whole system imaging quality. Optical alignment machining and precision alignment are combined to ensure the high co-axial precision of the optical system. An optical lens of high accuracy is assembled by using these methods; the final wave aberration of optical lens is 0.022λ.

  18. Optical computed tomography utilizing a rotating mirror and Fresnel lenses: operating principles and preliminary results.

    PubMed

    Xu, Y; Wuu, Cheng-Shie

    2013-02-07

    The performance of a fast optical computed tomography (CT) scanner based on a point laser source, a small area photodiode detector, and two optical-grade Fresnel lenses is evaluated. The OCTOPUS™-10× optical CT scanner (MGS Research Inc., Madison, CT) is an upgrade of the OCTOPUS™ research scanner with improved design for faster motion of the laser beam and faster data acquisition process. The motion of the laser beam in the new configuration is driven by the rotational motion of a scanning mirror. The center of the scanning mirror and the center of the photodiode detector are adjusted to be on the focal points of two coaxial Fresnel lenses. A glass water tank is placed between the two Fresnel lenses to house gel phantoms and matching liquids. The laser beam scans over the water tank in parallel beam geometry for projection data as the scanning mirror rotates at a frequency faster than 0.1 s per circle. Signal sampling is performed independently of the motion of the scanning mirror, to reduce the processing time for the synchronization of the stepper motors and the data acquisition board. An in-house developed reference image normalization mechanism is added to the image reconstruction program to correct the non-uniform light transmitting property of the Fresnel lenses. Technical issues with regard to the new design of the scanner are addressed, including projection data extraction from raw data samples, non-uniform pixel averaging and reference image normalization. To evaluate the dosimetric accuracy of the scanner, the reconstructed images from a 16 MeV, 6 cm × 6 cm electron field irradiation were compared with those from the Eclipse treatment planning system (Varian Corporation, Palo Alto, CA). The spatial resolution of the scanner is demonstrated to be of sub-millimeter accuracy. The effectiveness of the reference normalization method for correcting the non-uniform light transmitting property of the Fresnel lenses is analyzed. A sub

  19. Scalable quantum computing based on stationary spin qubits in coupled quantum dots inside double-sided optical microcavities.

    PubMed

    Wei, Hai-Rui; Deng, Fu-Guo

    2014-12-18

    Quantum logic gates are the key elements in quantum computing. Here we investigate the possibility of achieving a scalable and compact quantum computing based on stationary electron-spin qubits, by using the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics. We design the compact quantum circuits for implementing universal and deterministic quantum gates for electron-spin systems, including the two-qubit CNOT gate and the three-qubit Toffoli gate. They are compact and economic, and they do not require additional electron-spin qubits. Moreover, our devices have good scalability and are attractive as they both are based on solid-state quantum systems and the qubits are stationary. They are feasible with the current experimental technology, and both high fidelity and high efficiency can be achieved when the ratio of the side leakage to the cavity decay is low.

  20. Scalable quantum computing based on stationary spin qubits in coupled quantum dots inside double-sided optical microcavities

    PubMed Central

    Wei, Hai-Rui; Deng, Fu-Guo

    2014-01-01

    Quantum logic gates are the key elements in quantum computing. Here we investigate the possibility of achieving a scalable and compact quantum computing based on stationary electron-spin qubits, by using the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics. We design the compact quantum circuits for implementing universal and deterministic quantum gates for electron-spin systems, including the two-qubit CNOT gate and the three-qubit Toffoli gate. They are compact and economic, and they do not require additional electron-spin qubits. Moreover, our devices have good scalability and are attractive as they both are based on solid-state quantum systems and the qubits are stationary. They are feasible with the current experimental technology, and both high fidelity and high efficiency can be achieved when the ratio of the side leakage to the cavity decay is low. PMID:25518899

  1. Real-time optical correlator using computer-generated holographic filter on a liquid crystal light valve

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin; Yu, Jeffrey

    1990-01-01

    Limitations associated with the binary phase-only filter often used in optical correlators are presently circumvented in the writing of complex-valued data on a gray-scale spatial light modulator through the use of a computer-generated hologram (CGH) algorithm. The CGH encodes complex-valued data into nonnegative real CGH data in such a way that it may be encoded in any of the available gray-scale spatial light modulators. A CdS liquid-crystal light valve is used for the complex-valued CGH encoding; computer simulations and experimental results are compared, and the use of such a CGH filter as the synapse hologram in a holographic optical neural net is discussed.

  2. Scalable quantum computing based on stationary spin qubits in coupled quantum dots inside double-sided optical microcavities

    NASA Astrophysics Data System (ADS)

    Wei, Hai-Rui; Deng, Fu-Guo

    2014-12-01

    Quantum logic gates are the key elements in quantum computing. Here we investigate the possibility of achieving a scalable and compact quantum computing based on stationary electron-spin qubits, by using the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics. We design the compact quantum circuits for implementing universal and deterministic quantum gates for electron-spin systems, including the two-qubit CNOT gate and the three-qubit Toffoli gate. They are compact and economic, and they do not require additional electron-spin qubits. Moreover, our devices have good scalability and are attractive as they both are based on solid-state quantum systems and the qubits are stationary. They are feasible with the current experimental technology, and both high fidelity and high efficiency can be achieved when the ratio of the side leakage to the cavity decay is low.

  3. Diagnostic efficacy of computer extracted image features in optical coherence tomography of the precancerous cervix

    PubMed Central

    Kang, Wei; Qi, Xin; Tresser, Nancy J.; Kareta, Margarita; Belinson, Jerome L.; Rollins, Andrew M.

    2011-01-01

    Purpose: To determine the diagnostic efficacy of optical coherence tomography (OCT) to identify cervical intraepithelial neoplasia (CIN) grade 2 or higher by computer-aided diagnosis (CADx). Methods: OCT has been investigated as a screening∕diagnostic tool in the management of preinvasive and early invasive cancers of the uterine cervix. In this study, an automated algorithm was developed to extract OCT image features and identify CIN 2 or higher. First, the cervical epithelium was detected by a combined watershed and active contour method. Second, four features were calculated: The thickness of the epithelium and its standard deviation and the contrast between the epithelium and the stroma and its standard deviation. Finally, linear discriminant analysis was applied to classify images into two categories: Normal∕inflammation∕CIN 1 and CIN 2∕CIN 3. The algorithm was applied to 152 images (74 patients) obtained from an international study. Results: The numbers of normal∕inflammatory∕CIN 1∕CIN 2∕CIN 3 images are 74, 29, 14, 24, and 11, respectively. Tenfold cross-validation predicted the algorithm achieved a sensitivity of 51% (95% CI: 36%–67%) and a specificity of 92% (95% CI: 86%–96%) with an empirical two-category prior probability estimated from the data set. Receiver operating characteristic analysis yielded an area under the curve of 0.86. Conclusions: The diagnostic efficacy of CADx in OCT imaging to differentiate high-grade CIN from normal∕low grade CIN is demonstrated. The high specificity of OCT with CADx suggests further investigation as an effective secondary screening tool when combined with a highly sensitive primary screening tool. PMID:21361180

  4. Computer-Controlled Cylindrical Polishing Process for Development of Grazing Incidence Optics for Hard X-Ray Region

    NASA Technical Reports Server (NTRS)

    Khan, Gufran Sayeed; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    The presentation includes grazing incidence X-ray optics, motivation and challenges, mid spatial frequency generation in cylindrical polishing, design considerations for polishing lap, simulation studies and experimental results, future scope, and summary. Topics include current status of replication optics technology, cylindrical polishing process using large size polishing lap, non-conformance of polishin lap to the optics, development of software and polishing machine, deterministic prediction of polishing, polishing experiment under optimum conditions, and polishing experiment based on known error profile. Future plans include determination of non-uniformity in the polishing lap compliance, development of a polishing sequence based on a known error profile of the specimen, software for generating a mandrel polishing sequence, design an development of a flexible polishing lap, and computer controlled localized polishing process.

  5. A Micro-Computed Tomography Technique to Study the Quality of Fibre Optics Embedded in Composite Materials

    PubMed Central

    Chiesura, Gabriele; Luyckx, Geert; Voet, Eli; Lammens, Nicolas; Van Paepegem, Wim; Degrieck, Joris; Dierick, Manuel; Van Hoorebeke, Luc; Vanderniepen, Pieter; Sulejmani, Sanne; Sonnenfeld, Camille; Geernaert, Thomas; Berghmans, Francis

    2015-01-01

    Quality of embedment of optical fibre sensors in carbon fibre-reinforced polymers plays an important role in the resultant properties of the composite, as well as for the correct monitoring of the structure. Therefore, availability of a tool able to check the optical fibre sensor-composite interaction becomes essential. High-resolution 3D X-ray Micro-Computed Tomography, or Micro-CT, is a relatively new non-destructive inspection technique which enables investigations of the internal structure of a sample without actually compromising its integrity. In this work the feasibility of inspecting the position, the orientation and, more generally, the quality of the embedment of an optical fibre sensor in a carbon fibre reinforced laminate at unit cell level have been proven. PMID:25961383

  6. Fixed-point vs. floating-point arithmetic comparison for adaptive optics real-time control computation

    NASA Astrophysics Data System (ADS)

    Martín-Hernando, Yolanda; Rodríguez-Ramos, Luis F.; Garcia-Talavera, Marcos R.

    2008-07-01

    Most computers in the past have been equipped with floating point processing capabilities, allowing an easy and brute-force solution for the machine computation errors, not requiring any specific tailoring of the computation in nearly hundred percent of situations. However, the computation needed for the adaptive optics real-time control in 30-50 meter telescopes is big enough to cause trouble to conventional von-Neumann processors, even if Moore's Law is valid for the next years. Field Programmable Gate Array (FPGAs) have been proposed as a viable alternative to cope with such computation needs[1,2], but--at least today's chips--will require fixed-point arithmetic to be used instead. It is then important to evaluate up to what point the accuracy and stability of the control system will be affected by this limitation. This paper presents the simulation and laboratory results of the comparison between both arithmetics, specifically evaluated in an adaptive optics system. The real-time controller has been modeled as black box having as input the wavefront sensor camera digital output data, providing a digital output to the actuators of the deformable mirror, and with the task of internally computing all outputs from the inputs. MATLAB fixed-point library has been used to evaluate the effect of different precision lengths (5-10 fractional bits) in the computation of the Shack-Hartmann subaperture centroid, in comparison with the reference 64-bit floating-point arithmetic and with the noise floor of the real system, concluding that the effect of the limited precision can be overcome by adequately selecting the number of fractional bits used in the representation, and tailoring that number with the needs at every step of the algorithm.

  7. Development of electro-optical PCBs with embedded waveguides for data center and high performance computing applications

    NASA Astrophysics Data System (ADS)

    Immonen, M.; Wu, J.; Yan, H. J.; Zhu, L. X.; Chen, P.; Rapala-Virtanen, T.

    2014-03-01

    Power consumption and scaling the performance and quantity of electrical interconnects for data traffic inside boards and backplanes are one of the critical barriers envisaged in next-generation Data Center (DC) and High-Performance Computing (HPC) applications. In this paper, we report developments of electro-optical PCBs (EO-PCB) with embedded polymer waveguide layers. We show results for fabricating realistic product emulator test vehicles that comprise of reasonable form factor PCBs with optical and electrical layers. The optical layer comprise of multiple waveguides exhibiting a full range of geometric configurations required to meet practical optical routing functions. Test patterns include varied cross-sectional sizes, 90° bends of varying radii (40mm - 2mm), cascaded bends with varying radii, waveguide crossings with varied crossing angles (90° - 20°), splitters, tapered waveguides and waveguide interconnect to midboard interface slots. Moreover, results for fabricating electrical interconnect structures (e.g. tracing layers, vias, plated vias) top/bottom and through optical layers in OE-PCB stack are shown. The purpose of the complex routed copper layers is to enable the crucial demonstration of the fabrication and thermal robustness challenges inherent to electro-optical PCBs with optical layers. Process compatibility with accepted practices and challenges in production scale up for high volumes are key concerns to meet the yield target and cost efficiency. Results include waveguide characterization, waveguide transmission loss, misalignment tolerance, and effect of lamination. Moreover, we show results on waveguide termination by in-plane edge connector and with 90° out-of-plane couplers.

  8. Computer Tomography and Hybrid Optical/Digital Methods for Aerodynamic Measurements.

    DTIC Science & Technology

    1987-12-28

    Industrial Applications of Corn- on Axisymnnietric Flame ’Iempnlw res Measured by Holo- puted Tornographv arid NMI? Imiaging (Optical Society of graphic...Pontificia Universidad Catolica de Chile. Escuela de Ingenieria . Santiago, equal. The optical path length difference (OPD) be- Chile. tween the two rays

  9. Analog signal acquisition from computer optical disk drives for quantitative chemical sensing.

    PubMed

    Potyrailo, Radislav A; Morris, William G; Leach, Andrew M; Sivavec, Timothy M; Wisnudel, Marc B; Boyette, Scott

    2006-08-15

    Optoelectronic consumer products that are widely employed in the office and home attract attention for optical sensor applications due to (1) their cost advantage over analytical instruments produced only in small quantities, (2) robustness in operation due to the detailed manufacturability improvements, and (3) ease of operation. We demonstrate here a new approach for quantitative chemical/biochemical sensing when analog signals are acquired from conventional optical disk drives, and these signals are used for quantitative detection of optical changes of sensor films deposited on conventional CD and DVD optical disks. Because we do not alter manufacturing process of optical disks, any disk can be employed for deposition and readout of sensor films. The optical disk drives also perform their original function of reading and writing digital content to optical media because no optical modifications are introduced to obtain the analog signal. Such a sensor platform is quite universal and can be applied for chemical and biological quantitative detection, as well as for monitoring of changes of physical properties of regions deposited onto a CD or DVD (e.g., during combinatorial screening of materials). As a model example, we demonstrate the concept using chemical detection of ionic species such as Ca2+ in liquids (e.g., blood, urine, or water). Colorimetric calcium-sensitive sensor films were deposited onto a DVD, exposed to water with different concentrations of Ca2+, and quantified in the optical disk drive. The developed lab-on-DVD system demonstrated a 5 ppm detection limit of Ca2+ determinations, similar or slightly better than that achieved using a conventional fiber-optic portable spectrometer. This detection limit corresponded to a 0.023 absorbance unit resolution, as determined by the measurement of the same colorimetric films with a portable spectrometer. Determinations of Ca2+ unknowns using the lab-on-DVD system demonstrated +/-5 ppm accuracy and 2

  10. Ceramic and polymeric dental onlays evaluated by photo-elasticity, optical coherence tomography, and micro-computed tomography

    NASA Astrophysics Data System (ADS)

    Sinescu, Cosmin; Negrutiu, Meda; Topala, Florin; Ionita, Ciprian; Negru, Radu; Fabriky, Mihai; Marcauteanu, Corina; Bradu, Adrian; Dobre, George; Marsavina, Liviu; Rominu, Mihai; Podoleanu, Adrian

    2011-10-01

    Dental onlays are restorations used to repair rear teeth that have a mild to moderate amount of decay. They can also be used to restore teeth that are cracked or fractured if the damage is not severe enough to require a dental crown. The use of onlays requires less tooth reduction than does the use of metal fillings. This allows dentists to conserve more of a patient's natural tooth structure in the treatment process. The aims of this study are to evaluate the biomechanical comportment of the dental onlays, by using the 3D photo elasticity method and to investigate the integrity of the structures and their fitting to the dental support. For this optical coherence tomography and micro-computed tomography were employed. Both methods were used to investigate 37 dental onlays, 17 integral polymeric and 20 integral ceramic. The results permit to observe materials defects inside the ceramic or polymeric onlays situate in the biomechanically tensioned areas that could lead to fracture of the prosthetic structure. Marginal fitting problems of the onlays related to the teeth preparations were presented in order to observe the possibility of secondary cavities. The resulted images from the optical coherence tomography were verified by the micro-computed tomography. In conclusion, the optical coherence tomography can be used as a clinical method in order to evaluate the integrity of the dental ceramic and polymeric onlays and to investigate the quality of the marginal fitting to the teeth preparations.

  11. Fast computation of Fresnel diffraction field of a three-dimensional object for a pixelated optical device.

    PubMed

    Esmer, G Bora

    2013-01-01

    In this paper, a fast algorithm is proposed for accurate calculation of the scalar optical diffraction on a pixelated optical device used in the reconstruction process from a three-dimensional object that is formed by scattered sample points over the space. In computer-generated holography, fast and accurate calculation of the diffraction field is an important and a challenging problem. Therefore, several fast algorithms can be found in the literature. The accuracy of the calculations can be determined by the signal processing techniques and the numerical methods used in the calculation of diffraction fields. Furthermore, the quality of reconstructed objects can be affected by the properties of optical devices employed in the reconstruction process. For instance, the pixelated structure of those devices has a significant effect on the reconstruction process. Therefore, the pixelated structure of the display device has to be taken into account. Furthermore, fast calculation of the diffraction pattern can be a bottleneck in dynamic holographic content generation. As a solution to the problems, we propose a fast and accurate algorithm based on a precomputed one-dimensional kernel and scaling of that kernel for the computation of the diffraction pattern for a pixelated display.

  12. Nonlinear tunneling of optical soliton in 3 coupled NLS equation with symbolic computation

    NASA Astrophysics Data System (ADS)

    Mani Rajan, M. S.; Mahalingam, A.; Uthayakumar, A.

    2014-07-01

    We investigated the soliton solution for N coupled nonlinear Schrödinger (CNLS) equations. These equations are coupled due to the cross-phase-modulation (CPM). Lax pair of this system is obtained via the Ablowitz-Kaup-Newell-Segur (AKNS) scheme and the corresponding Darboux transformation is constructed to derive the soliton solution. One and two soliton solutions are generated. Using two soliton solutions of 3 CNLS equation, nonlinear tunneling of soliton for both with and without exponential background has been discussed. Finally cascade compression of optical soliton through multi-nonlinear barrier has been discussed. The obtained results may have promising applications in all-optical devices based on optical solitons, study of soliton propagation in birefringence fiber systems and optical soliton with distributed dispersion and nonlinearity management.

  13. Smart-phone based computational microscopy using multi-frame contact imaging on a fiber-optic array.

    PubMed

    Navruz, Isa; Coskun, Ahmet F; Wong, Justin; Mohammad, Saqib; Tseng, Derek; Nagi, Richie; Phillips, Stephen; Ozcan, Aydogan

    2013-10-21

    We demonstrate a cellphone based contact microscopy platform, termed Contact Scope, which can image highly dense or connected samples in transmission mode. Weighing approximately 76 grams, this portable and compact microscope is installed on the existing camera unit of a cellphone using an opto-mechanical add-on, where planar samples of interest are placed in contact with the top facet of a tapered fiber-optic array. This glass-based tapered fiber array has ~9 fold higher density of fiber optic cables on its top facet compared to the bottom one and is illuminated by an incoherent light source, e.g., a simple light-emitting-diode (LED). The transmitted light pattern through the object is then sampled by this array of fiber optic cables, delivering a transmission image of the sample onto the other side of the taper, with ~3× magnification in each direction. This magnified image of the object, located at the bottom facet of the fiber array, is then projected onto the CMOS image sensor of the cellphone using two lenses. While keeping the sample and the cellphone camera at a fixed position, the fiber-optic array is then manually rotated with discrete angular increments of e.g., 1-2 degrees. At each angular position of the fiber-optic array, contact images are captured using the cellphone camera, creating a sequence of transmission images for the same sample. These multi-frame images are digitally fused together based on a shift-and-add algorithm through a custom-developed Android application running on the smart-phone, providing the final microscopic image of the sample, visualized through the screen of the phone. This final computation step improves the resolution and also removes spatial artefacts that arise due to non-uniform sampling of the transmission intensity at the fiber optic array surface. We validated the performance of this cellphone based Contact Scope by imaging resolution test charts and blood smears.

  14. Optical Computing. Organization of the 1993 Photonics Science Topical Meetings Held in Palm Springs, California on March 16 - 19, 1993. Technical Digest Series, Volume 7

    DTIC Science & Technology

    1993-03-19

    network Implementation using 9:20 am asymmetric Fabry-Perot modulators, Andrew Jennings, Brian OWA3 Multiwavelength optical half adder, Pochi Yeh... multiwavelength optical half adder. (p. 68) nects. (p. 96) 9:40 am 2:50 pm OWA4 Wavelength multiplexed computer-generated volume OWC3 Content addramble...ATMOS and OSCAR are RACE projects, mentioned in the text shape this into new systems architectures, ("optical ether"). Broadly speaking, this has led to

  15. Computer-aided, multi-modal, and compression diffuse optical studies of breast tissue

    NASA Astrophysics Data System (ADS)

    Busch, David Richard, Jr.

    Diffuse Optical Tomography and Spectroscopy permit measurement of important physiological parameters non-invasively through ˜10 cm of tissue. I have applied these techniques in measurements of human breast and breast cancer. My thesis integrates three loosely connected themes in this context: multi-modal breast cancer imaging, automated data analysis of breast cancer images, and microvascular hemodynamics of breast under compression. As per the first theme, I describe construction, testing, and the initial clinical usage of two generations of imaging systems for simultaneous diffuse optical and magnetic resonance imaging. The second project develops a statistical analysis of optical breast data from many spatial locations in a population of cancers to derive a novel optical signature of malignancy; I then apply this data-derived signature for localization of cancer in additional subjects. Finally, I construct and deploy diffuse optical instrumentation to measure blood content and blood flow during breast compression; besides optics, this research has implications for any method employing breast compression, e.g., mammography.

  16. Computational and in vivo investigation of optical reflectance from human brain to assist neurosurgery.

    PubMed

    Johns, M; Giller, C; Liu, H

    1998-10-01

    Parkinson's disease (PD) is a chronic, progressive disease involving the globus pallidus (GP), which is a gray matter mass, surrounded by white matter deep within the brain. During a neurosurgery procedure, a thin probe is inserted into the GP to create a lesion that often relieves the cardinal symptoms of PD. The goal of this study is to develop an optical method to accurately locate the GP border. In theory, Monte Carlo simulations were performed to predict the optical reflectance from brain tissue. In experiment, a portable, real-time display spectrometer with a fiber optic reflectance probe was developed and used during human surgery. Optical reflectance values were recorded at 1 mm intervals to obtain a spatial profile of the tissue as the probe passed through regions of gray and white matter. The simulation and in vivo studies of the reflectance from the brain are in good agreement with one another. The clinical data show that the reflectance from gray matter is approximately 50% or less than that from white matter between 650 and 800 nm. A slope algorithm is developed to distinguish gray and white matter in vivo. This study provides previously unknown optical reflectance of the human brain. © 1998 Society of Photo-Optical Instrumentation Engineers.

  17. High-efficient computer-generated integral imaging based on the backward ray-tracing technique and optical reconstruction.

    PubMed

    Xing, Shujun; Sang, Xinzhu; Yu, Xunbo; Duo, Chen; Pang, Bo; Gao, Xin; Yang, Shenwu; Guan, YanXin; Yan, Binbin; Yuan, Jinhui; Wang, Kuiru

    2017-01-09

    A high-efficient computer-generated integral imaging (CGII) method is presented based on the backward ray-tracing technique. In traditional CGII methods, the total rendering time is long, because a large number of cameras are established in the virtual world. The ray origin and the ray direction for every pixel in elemental image array are calculated with the backward ray-tracing technique, and the total rendering time can be noticeably reduced. The method is suitable to create high quality integral image without the pseudoscopic problem. Real time and non-real time CGII rendering images and optical reconstruction are demonstrated, and the effectiveness is verified with different types of 3D object models. Real time optical reconstruction with 90 × 90 viewpoints and the frame rate above 40 fps for the CGII 3D display are realized without the pseudoscopic problem.

  18. Controlling light with freeform optics: recent progress in computational methods for optical design of freeform lenses with prescribed irradiance properties

    NASA Astrophysics Data System (ADS)

    Oliker, Vladimir I.; Cherkasskiy, Boris

    2014-09-01

    Structural color is produced when nanostructures called schemochromes alter light reflected from a surface through different optic principles, in contrast with other types of colors that are produced when pigments selectively absorb certain wavelengths of light. Research on biogenic photonic nanostructures has focused primarily on bird feathers, butterfly wings and beetle elytra, ignoring other diverse groups such as spiders. We argue that spiders are a good model system to study the functions and evolution of colors in nature for the following reasons. First, these colors clearly function in spiders such as the tarantulas outside of sexual selection, which is likely the dominant driver of the evolution of structural colors in birds and butterflies. Second, within more than 44,000 currently known spider species, colors are used in every possible way based on the same sets of relatively simple materials. Using spiders, we can study how colors evolve to serve different functions under a variety of combinations of driving forces, and how those colors are produced within a relatively simple system. Here, we first review the different color-producing materials and mechanisms (i.e., light absorbing, reflecting and emitting) in birds, butterflies and beetles, the interactions between these different elements, and the functions of colors in different organisms. We then summarize the current state of knowledge of spider colors and compare it with that of birds and insects. We then raise questions including: 1. Could spiders use fluorescence as a mechanism to protect themselves from UV radiation, if they do not have the biosynthetic pathways to produce melanins? 2. What functions could color serve for nearly blind tarantulas? 3. Why are only multilayer nanostructures (thus far) found in spiders, while birds and butterflies use many diverse nanostructures? And, does this limit the diversity of structural colors found in spiders? Answering any of these questions in the future

  19. Synthesis and experimental-computational characterization of nonlinear optical properties of triazacyclopentafluorene-coumarin derivatives

    NASA Astrophysics Data System (ADS)

    García, Santiago; Vázquez, Juan L.; Rentería, Marvin; Aguilar-Garduño, Isis G.; Delgado, Francisco; Trejo-Durán, Mónica; García-Revilla, Marco A.; Alvarado-Méndez, Edgar; Vázquez, Miguel A.

    2016-12-01

    A series of novel 3-(2,2a,3-triazacyclopenta[jk]fluoren-1-yl)-2H-chromen-2-one derivatives 5a-c have been synthesized by [8 + 2] cycloaddition reaction between the corresponding 3-(imidazo[1,2-a]pyrimidines)-2-yl)-2H-chromen-2-one 4a-c with 2-(trimethylsilyl)phenyl triflates as benzyne precursor in 65-80% yields. The strategic incorporation of triazacyclopentafluorene group at the 3-position of the coumarin molecules resulted in dyes with excellent nonlinear optical properties. The nonlinear optical properties of third order (compounds 5a-c) were studied using Z-scan technique. The high nonlinear response is of 10-7 cm2/W order. The nonlinearity of the compounds is an indication of a promising material for applications at low power, such as optical switching, waveguides, nonlinear contrast phase, among others. Theoretical results of HOMO-LUMO gaps and oscillator strengths are used to rationalize the high efficiency of the novel compound in the nonlinear optical behavior. In particular, 5b displays the best nonlinear optical properties and at the same time the smaller HOMO-LUMO gap and the highest oscillator strength.

  20. Theory and practice of ubiquitous quantitative chemical analysis using conventional computer optical disk drives

    NASA Astrophysics Data System (ADS)

    Potyrailo, Radislav A.; Morris, William G.; Leach, Andrew M.; Hassib, Lamyaa; Krishnan, Kasiraman; Surman, Cheryl; Wroczynski, Ronald; Boyette, Scott; Xiao, Caibin; Shrikhande, Prashant; Agree, Alan; Cecconie, Ted

    2007-10-01

    We demonstrate a new attractive approach for ubiquitous quantitative chemical or biological sensing when analog signals are acquired from conventional optical disk drives, and these signals are used for quantitative detection of optical changes of sensing films deposited on conventional CD and DVD optical disks. Our developed analytical model of the operation of this Lab-on-DVD system describes the optical response of sensing films deposited onto the read surface of optical disks by taking into account the practical aspects of system performance that include possible reagent leaching effects, water sampling (delivering) efficiency, and possible changes of the film morphology after water removal. By applying a screen-printing process, we demonstrated a laboratory-scale automated production of sensing films with an average thickness of ˜10 μm and a thickness relative standard deviation of <3% across multiple films. Finally, we developed a system for delivery of water-sample volumes to sensing films on the disk that utilized a multifunctional jewel case assembly.

  1. Fast calculation method of computer generated hologram animation for viewpoint parallel shift and rotation using Fourier transform optical system.

    PubMed

    Watanabe, Ryosuke; Yamaguchi, Kazuhiro; Sakamoto, Yuji

    2016-01-20

    Computer generated hologram (CGH) animations can be made by switching many CGHs on an electronic display. Some fast calculation methods for CGH animations have been proposed, but one for viewpoint movement has not been proposed. Therefore, we designed a fast calculation method of CGH animations for viewpoint parallel shifts and rotation. A Fourier transform optical system was adopted to expand the viewing angle. The results of experiments were that the calculation time of our method was over 6 times faster than that of the conventional method. Furthermore, the degradation in CGH animation quality was found to be sufficiently small.

  2. Dental wear estimation using a digital intra-oral optical scanner and an automated 3D computer vision method.

    PubMed

    Meireles, Agnes Batista; Vieira, Antonio Wilson; Corpas, Livia; Vandenberghe, Bart; Bastos, Flavia Souza; Lambrechts, Paul; Campos, Mario Montenegro; Las Casas, Estevam Barbosa de

    2016-01-01

    The objective of this work was to propose an automated and direct process to grade tooth wear intra-orally. Eight extracted teeth were etched with acid for different times to produce wear and scanned with an intra-oral optical scanner. Computer vision algorithms were used for alignment and comparison among models. Wear volume was estimated and visual scoring was achieved to determine reliability. Results demonstrated that it is possible to directly detect submillimeter differences in teeth surfaces with an automated method with results similar to those obtained by direct visual inspection. The investigated method proved to be reliable for comparison of measurements over time.

  3. Computer simulation on the collision-sticking dynamics of two colloidal particles in an optical trap.

    PubMed

    Xu, Shenghua; Sun, Zhiwei

    2007-04-14

    Collisions of a particle pair induced by optical tweezers have been employed to study colloidal stability. In order to deepen insights regarding the collision-sticking dynamics of a particle pair in the optical trap that were observed in experimental approaches at the particle level, the authors carry out a Brownian dynamics simulation. In the simulation, various contributing factors, including the Derjaguin-Landau-Verwey-Overbeek interaction of particles, hydrodynamic interactions, optical trapping forces on the two particles, and the Brownian motion, were all taken into account. The simulation reproduces the tendencies of the accumulated sticking probability during the trapping duration for the trapped particle pair described in our previous study and provides an explanation for why the two entangled particles in the trap experience two different statuses.

  4. The role of robotics in computer controlled polishing of large and small optics

    NASA Astrophysics Data System (ADS)

    Walker, David; Dunn, Christina; Yu, Guoyu; Bibby, Matt; Zheng, Xiao; Wu, Hsing Yu; Li, Hongyu; Lu, Chunlian

    2015-08-01

    Following formal acceptance by ESO of three 1.4m hexagonal off-axis prototype mirror segments, one circular segment, and certification of our optical test facility, we turn our attention to the challenge of segment mass-production. In this paper, we focus on the role of industrial robots, highlighting complementarity with Zeeko CNC polishing machines, and presenting results using robots to provide intermediate processing between CNC grinding and polishing. We also describe the marriage of robots and Zeeko machines to automate currently manual operations; steps towards our ultimate vision of fully autonomous manufacturing cells, with impact throughout the optical manufacturing community and beyond.

  5. Read-out optical schemes for holographic memory system based on multiplexed computer generated 1D Fourier holograms

    NASA Astrophysics Data System (ADS)

    Donchenko, Sergey S.; Odinokov, Sergey B.; Bobrinev, Vladimir I.; Betin, Alexandr Y.; Zlokazov, Evgenie Y.

    2015-05-01

    Computer holographic synthesis allows to significantly simplify the recording scheme of microholograms in holographic memory system as the classic high precision holographic setup based on two-beam interference is removed by simple scale reduction projection scheme. Application of computer generated 1D-Fourier holograms provides the possibility of selective reconstruction of the multiplexed holograms with different orientation of data lines by corresponding rotation of anamorphic objective (cylindrical lens), used in the read-out systems. Two configurations of read-out optical scheme were investigated by our team: full-page scheme and line-by-line scheme. In the present article we report the specificities of these schemes and consider their advantages and disadvantages. The results of experimental modeling of both read-out configurations are also presented.

  6. Computational analysis of responses of a wedge-shaped-tip optical fiber probe in bubble measurement

    NASA Astrophysics Data System (ADS)

    Sakamoto, A.; Saito, T.

    2012-07-01

    Optical-fiber probing is widely employed in bubble/droplet measurement in gas-liquid two-phase flows. Several types of optical fiber probes with a very high S/N ratio and high performance have been developed, but further improvement in the probes' measurement accuracy and reliability for industrial applications is desired. We tried to eliminate optical noise in the probe measurements, and we found that the signals include some peak signs that have potential for advanced measurement with optical-fiber probing. We developed a ray-tracing numerical simulator and identified the mechanisms underlying the generation of the signals. In order to numerically simulate the optical probing signals, the simulator must use 3D frameworks composed of incident beams, the reflection and refraction on the surfaces of the optical elements (i.e., an optical fiber, a sensing tip, an air phase, and a water phase), and beams returning from the sensing tip to the other tip through the fiber. We used all of these in a simple rendering framework based on a ray-tracing algorithm with Fresnel's law, and we observed the mechanism of some promising signals that may be useful for extracting the hidden potential of optical-fiber probing. To verify the simulator's performance, we carried out three comparative experiments with fundamental setups using a wedge-shaped single-tip optical fiber probe, examining: (1) the beam trajectories and energy leaking out from the sensing tip into the surrounding air phase or water phase, (2) the probing signals throughout penetration of the sensing tip at the air-water free interface in light of the three-dimensional deformation, and (3) the probing signals throughout penetration of the sensing tip into a bubble in light of the three-dimensional bubble shape. As a result, (a) we found that an optical fiber probe with a wedge-shaped tip has particular characteristics of beam emissions from the tip, and the emitting angles switched depending on the phases covering

  7. Computational analysis of responses of a wedge-shaped-tip optical fiber probe in bubble measurement.

    PubMed

    Sakamoto, A; Saito, T

    2012-07-01

    Optical-fiber probing is widely employed in bubble/droplet measurement in gas-liquid two-phase flows. Several types of optical fiber probes with a very high S/N ratio and high performance have been developed, but further improvement in the probes' measurement accuracy and reliability for industrial applications is desired. We tried to eliminate optical noise in the probe measurements, and we found that the signals include some peak signs that have potential for advanced measurement with optical-fiber probing. We developed a ray-tracing numerical simulator and identified the mechanisms underlying the generation of the signals. In order to numerically simulate the optical probing signals, the simulator must use 3D frameworks composed of incident beams, the reflection and refraction on the surfaces of the optical elements (i.e., an optical fiber, a sensing tip, an air phase, and a water phase), and beams returning from the sensing tip to the other tip through the fiber. We used all of these in a simple rendering framework based on a ray-tracing algorithm with Fresnel's law, and we observed the mechanism of some promising signals that may be useful for extracting the hidden potential of optical-fiber probing. To verify the simulator's performance, we carried out three comparative experiments with fundamental setups using a wedge-shaped single-tip optical fiber probe, examining: (1) the beam trajectories and energy leaking out from the sensing tip into the surrounding air phase or water phase, (2) the probing signals throughout penetration of the sensing tip at the air-water free interface in light of the three-dimensional deformation, and (3) the probing signals throughout penetration of the sensing tip into a bubble in light of the three-dimensional bubble shape. As a result, (a) we found that an optical fiber probe with a wedge-shaped tip has particular characteristics of beam emissions from the tip, and the emitting angles switched depending on the phases covering

  8. Fault-tolerant linear optical quantum computing with small-amplitude coherent States.

    PubMed

    Lund, A P; Ralph, T C; Haselgrove, H L

    2008-01-25

    Quantum computing using two coherent states as a qubit basis is a proposed alternative architecture with lower overheads but has been questioned as a practical way of performing quantum computing due to the fragility of diagonal states with large coherent amplitudes. We show that using error correction only small amplitudes (alpha>1.2) are required for fault-tolerant quantum computing. We study fault tolerance under the effects of small amplitudes and loss using a Monte Carlo simulation. The first encoding level resources are orders of magnitude lower than the best single photon scheme.

  9. A computer graphics based model for scattering from objects of arbitrary shapes in the optical region

    NASA Technical Reports Server (NTRS)

    Goel, Narendra S.; Rozehnal, Ivan; Thompson, Richard L.

    1991-01-01

    A computer-graphics-based model, named DIANA, is presented for generation of objects of arbitrary shape and for calculating bidirectional reflectances and scattering from them, in the visible and infrared region. The computer generation is based on a modified Lindenmayer system approach which makes it possible to generate objects of arbitrary shapes and to simulate their growth, dynamics, and movement. Rendering techniques are used to display an object on a computer screen with appropriate shading and shadowing and to calculate the scattering and reflectance from the object. The technique is illustrated with scattering from canopies of simulated corn plants.

  10. Computationally efficient scalar nonparaxial modeling of optical wave propagation in the far-field.

    PubMed

    Nguyen, Giang-Nam; Heggarty, Kevin; Gérard, Philippe; Serio, Bruno; Meyrueis, Patrick

    2014-04-01

    We present a scalar model to overcome the computation time and sampling interval limitations of the traditional Rayleigh-Sommerfeld (RS) formula and angular spectrum method in computing wide-angle diffraction in the far-field. Numerical and experimental results show that our proposed method based on an accurate nonparaxial diffraction step onto a hemisphere and a projection onto a plane accurately predicts the observed nonparaxial far-field diffraction pattern, while its calculation time is much lower than the more rigorous RS integral. The results enable a fast and efficient way to compute far-field nonparaxial diffraction when the conventional Fraunhofer pattern fails to predict correctly.

  11. In-situ imaging of articular cartilage of the first carpometacarpal joint using co-registered optical coherence tomography and computed tomography

    NASA Astrophysics Data System (ADS)

    Cernohorsky, Paul; de Bruin, Daniel M.; van Herk, Marcel; Bras, Johannes; Faber, Dirk J.; Strackee, Simon D.; van Leeuwen, Ton G.

    2012-06-01

    Conventional imaging modalities are unable to depict the early degeneration of articular cartilage in osteoarthritis, especially in small joints. Optical coherence tomography has previously been used successfully in high-resolution imaging of cartilage tissue. This pilot cadaver study demonstrates the use of intra-articular optical coherence tomography in imaging of articular cartilage of the first carpometacarpal joint, producing high resolution images of the articular surface in which cartilage thickness and surface characteristics were assessed. Findings on optical coherence tomography were confirmed with histology. Furthermore, co-registration of optical coherence tomography and computed tomography was used to accurately determine the scanned trajectory and reconstruct a true-scale image overlay.

  12. Parallel distributed free-space optoelectronic computer engine using flat plug-on-top optics package

    NASA Astrophysics Data System (ADS)

    Berger, Christoph; Ekman, Jeremy T.; Wang, Xiaoqing; Marchand, Philippe J.; Spaanenburg, Henk; Kiamilev, Fouad E.; Esener, Sadik C.

    2000-05-01

    We report about ongoing work on a free-space optical interconnect system, which will demonstrate a Fast Fourier Transformation calculation, distributed among six processor chips. Logically, the processors are arranged in two linear chains, where each element communicates optically with its nearest neighbors. Physically, the setup consists of a large motherboard, several multi-chip carrier modules, which hold the processor/driver chips and the optoelectronic chips (arrays of lasers and detectors), and several plug-on-top optics modules, which provide the optical links between the chip carrier modules. The system design tries to satisfy numerous constraints, such as compact size, potential for mass-production, suitability for large arrays (up to 1024 parallel channels), compatibility with standard electronics fabrication and packaging technology, potential for active misalignment compensation by integration MEMS technology, and suitability for testing different imaging topologies. We present the system architecture together with details of key components and modules, and report on first experiences with prototype modules of the setup.

  13. Excitation spectroscopy in multispectral optical fluorescence tomography: methodology, feasibility and computer simulation studies

    NASA Astrophysics Data System (ADS)

    Chaudhari, Abhijit J.; Ahn, Sangtae; Levenson, Richard; Badawi, Ramsey D.; Cherry, Simon R.; Leahy, Richard M.

    2009-08-01

    Molecular probes used for in vivo optical fluorescence tomography (OFT) studies in small animals are typically chosen such that their emission spectra lie in the 680-850 nm wavelength range. This is because tissue attenuation in this spectral band is relatively low, allowing optical photons even from deep sites in tissue to reach the animal surface and consequently be detected by a CCD camera. The wavelength dependence of tissue optical properties within the 680-850 nm band can be exploited for emitted light by measuring fluorescent data via multispectral approaches and incorporating the spectral dependence of these optical properties into the OFT inverse problem—that of reconstructing underlying 3D fluorescent probe distributions from optical data collected on the animal surface. However, in the aforementioned spectral band, due to only small variations in the tissue optical properties, multispectral emission data, though superior for image reconstruction compared to achromatic data, tend to be somewhat redundant. A different spectral approach for OFT is to capitalize on the larger variations in the optical properties of tissue for excitation photons than for the emission photons by using excitation at multiple wavelengths as a means of decoding source depth in tissue. The full potential of spectral approaches in OFT can be realized by a synergistic combination of these two approaches, that is, exciting the underlying fluorescent probe at multiple wavelengths and measuring emission data multispectrally. In this paper, we describe a method that incorporates both excitation and emission spectral information into the OFT inverse problem. We describe a linear algebraic formulation of the multiple wavelength illumination-multispectral detection forward model for OFT and compare it to models that use only excitation at multiple wavelengths or those that use only multispectral detection techniques. This study is carried out in a realistic inhomogeneous mouse atlas

  14. Deterministic Computer-Controlled Polishing Process for High-Energy X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    A deterministic computer-controlled polishing process for large X-ray mirror mandrels is presented. Using tool s influence function and material removal rate extracted from polishing experiments, design considerations of polishing laps and optimized operating parameters are discussed

  15. Synthesis, structure, spectroscopic investigations, and computational studies of optically pure β-ketoamide

    NASA Astrophysics Data System (ADS)

    Mtat, D.; Touati, R.; Guerfel, T.; Walha, K.; Ben Hassine, B.

    2016-12-01

    Chemical preparation, X-ray single crystal diffraction, IR and NMR spectroscopic investigations of a novel nonlinear optical organic compound (C17H22NO2Cl) are described. The compound crystallizes in the orthorhombic system with the non-centrosymmetric sp. gr. P212121. In the crystal structure, molecules are interconnected by N-H…O hydrogen bonds forming infinite chains along a axis. The Hirshfeld surface and associated fingerprint plots of the compound are presented to explore the nature of intermolecular interactions and their relative contributions in building the solid-state architecture. The molecular HOMO-LUMO compositions and their respective energy gaps are also drawn to explain the activity of the compound. The first hyperpolarizability βtot of the title compound is determined using DFT calculations. The optical properties are also investigated by UV-Vis absorption spectrum.

  16. Confidence range estimate of extended source imagery acquisition algorithms via computer simulations. [in optical communication systems

    NASA Technical Reports Server (NTRS)

    Chen, CHIEN-C.; Hui, Elliot; Okamoto, Garret

    1992-01-01

    Spatial acquisition using the sun-lit Earth as a beacon source provides several advantages over active beacon-based systems for deep-space optical communication systems. However, since the angular extend of the Earth image is large compared to the laser beam divergence, the acquisition subsystem must be capable of resolving the image to derive the proper pointing orientation. The algorithms used must be capable of deducing the receiver location given the blurring introduced by the imaging optics and the large Earth albedo fluctuation. Furthermore, because of the complexity of modelling the Earth and the tracking algorithms, an accurate estimate of the algorithm accuracy can only be made via simulation using realistic Earth images. An image simulator was constructed for this purpose, and the results of the simulation runs are reported.

  17. Computational manufacturing of optical interference coatings: method, simulation results, and comparison with experiment.

    PubMed

    Friedrich, Karen; Wilbrandt, Steffen; Stenzel, Olaf; Kaiser, Norbert; Hoffmann, Karl Heinz

    2010-06-01

    Virtual deposition runs have been performed to estimate the production yield of selected oxide optical interference coatings when plasma ion-assisted deposition with an advanced plasma source is applied. Thereby, deposition of each layer can be terminated either by broadband optical monitoring or quartz crystal monitoring. Numerous deposition runs of single-layer coatings have been performed to investigate the reproducibility of coating properties and to quantify deposition errors for the simulation. Variations of the following parameters are considered in the simulation: refractive index, extinction coefficient, and film thickness. The refractive index and the extinction coefficient are simulated in terms of the oscillator model. The parameters are varied using an apodized normal distribution with known mean value and standard deviation. Simulation of variations in the film thickness is performed specific to the selected monitoring strategy. Several deposition runs of the selected oxide interference coatings have been performed to verify the simulation results by experimental data.

  18. Quantum Computation with Neutral Atoms at Addressable Optical Lattice Sites and Atoms in Confined Geometries

    DTIC Science & Technology

    2014-10-13

    SECURITY CLASSIFICATION OF: We have performed a set of experiments using arrays of 1D Bose gases in various configurations. Uncoupled 1D gases have been...used to study the limits of statistical mechanics near integrable points. We have shown that nearly integrable gases thermalize at an even slower...NAME(S) AND ADDRESS (ES) U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 ultracold atoms, optical lattices, 1D gases

  19. Computational Study of Chalcopyrite Semiconductors and Their Non-Linear Optical Properties

    DTIC Science & Technology

    2007-09-12

    Daniel J. Friedman, Omar Manasreh, Irina A. Buyanova, Anneli Munkholm, F. Danie Auret, Mat. Res. Soc. Symp. Proc. Vol. 799, Z5.3.1 (2004). d...optical proper- ties on the composition of the materials; (3) understand the trends in the family of chalcopyrite semicondutors and related materials with...Friedman, Omar Manasreh, Irina A. Buyanova, Anneli Munkholm, F. Danie Auret, Mat. Res. Soc. Symp. Proc. Vol. 799, Z5.3.1 (2004). [2] "Theoretical study of

  20. Optical tracking of contrast medium bolus to optimize bolus shape and timing in dynamic computed tomography

    NASA Astrophysics Data System (ADS)

    Eisa, Fabian; Brauweiler, Robert; Peetz, Alexander; Hupfer, Martin; Nowak, Tristan; Kalender, Willi A.

    2012-05-01

    One of the biggest challenges in dynamic contrast-enhanced CT is the optimal synchronization of scan start and duration with contrast medium administration in order to optimize image contrast and to reduce the amount of contrast medium. We present a new optically based approach, which was developed to investigate and optimize bolus timing and shape. The time-concentration curve of an intravenously injected test bolus of a dye is measured in peripheral vessels with an optical sensor prior to the diagnostic CT scan. The curves can be used to assess bolus shapes as a function of injection protocols and to determine contrast medium arrival times. Preliminary results for phantom and animal experiments showed the expected linear behavior between dye concentration and absorption. The kinetics of the dye was compared to iodinated contrast medium and was found to be in good agreement. The contrast enhancement curves were reliably detected in three mice with individual bolus shapes and delay times of 2.1, 3.5 and 6.1 s, respectively. The optical sensor appears to be a promising approach to optimize injection protocols and contrast enhancement timing and is applicable to all modalities without implying any additional radiation dose. Clinical tests are still necessary.

  1. Computer driven optical keratometer and method of evaluating the shape of the cornea

    NASA Technical Reports Server (NTRS)

    Baroth, Edmund C. (Inventor); Mouneimme, Samih A. (Inventor)

    1994-01-01

    An apparatus and method for measuring the shape of the cornea utilize only one reticle to generate a pattern of rings projected onto the surface of a subject's eye. The reflected pattern is focused onto an imaging device such as a video camera and a computer compares the reflected pattern with a reference pattern stored in the computer's memory. The differences between the reflected and stored patterns are used to calculate the deformation of the cornea which may be useful for pre-and post-operative evaluation of the eye by surgeons.

  2. Continuous-variable quantum computing in optical time-frequency modes using quantum memories.

    PubMed

    Humphreys, Peter C; Kolthammer, W Steven; Nunn, Joshua; Barbieri, Marco; Datta, Animesh; Walmsley, Ian A

    2014-09-26

    We develop a scheme for time-frequency encoded continuous-variable cluster-state quantum computing using quantum memories. In particular, we propose a method to produce, manipulate, and measure two-dimensional cluster states in a single spatial mode by exploiting the intrinsic time-frequency selectivity of Raman quantum memories. Time-frequency encoding enables the scheme to be extremely compact, requiring a number of memories that are a linear function of only the number of different frequencies in which the computational state is encoded, independent of its temporal duration. We therefore show that quantum memories can be a powerful component for scalable photonic quantum information processing architectures.

  3. Optical phase step method for absolute ranging interferometry using computer-generated holograms

    NASA Astrophysics Data System (ADS)

    Deininger, Martin; Wang, Lingli; Gerstner, Klaus; Tschudi, Theo

    1995-09-01

    One main problem of an interferometric measurement is to evaluate the object distance from the interference function. One of the known methods that delivers the object phase is the phase step method. Here we introduce computer-generated holograms to realize parallel phase steps without phase modulation of the reference path.

  4. Computationally efficient analysis of extraordinary optical transmission through infinite and truncated subwavelength hole arrays

    NASA Astrophysics Data System (ADS)

    Camacho, Miguel; Boix, Rafael R.; Medina, Francisco

    2016-06-01

    The authors present a computationally efficient technique for the analysis of extraordinary transmission through both infinite and truncated periodic arrays of slots in perfect conductor screens of negligible thickness. An integral equation is obtained for the tangential electric field in the slots both in the infinite case and in the truncated case. The unknown functions are expressed as linear combinations of known basis functions, and the unknown weight coefficients are determined by means of Galerkin's method. The coefficients of Galerkin's matrix are obtained in the spatial domain in terms of double finite integrals containing the Green's functions (which, in the infinite case, is efficiently computed by means of Ewald's method) times cross-correlations between both the basis functions and their divergences. The computation in the spatial domain is an efficient alternative to the direct computation in the spectral domain since this latter approach involves the determination of either slowly convergent double infinite summations (infinite case) or slowly convergent double infinite integrals (truncated case). The results obtained are validated by means of commercial software, and it is found that the integral equation technique presented in this paper is at least two orders of magnitude faster than commercial software for a similar accuracy. It is also shown that the phenomena related to periodicity such as extraordinary transmission and Wood's anomaly start to appear in the truncated case for arrays with more than 100 (10 ×10 ) slots.

  5. Physics Education through Computational Tools: The Case of Geometrical and Physical Optics

    ERIC Educational Resources Information Center

    Rodríguez, Y.; Santana, A.; Mendoza, L. M.

    2013-01-01

    Recently, with the development of more powerful and accurate computational tools, the inclusion of new didactic materials in the classroom is known to have increased. However, the form in which these materials can be used to enhance the learning process is still under debate. Many different methodologies have been suggested for constructing new…

  6. An Optical and Computational Investigation on the Effects of Transient Fuel Injections in Internal Combustion Engines

    NASA Astrophysics Data System (ADS)

    Neal, Nicholas

    The effects of transient rate-of-injection profiles on high-pressure fuel jets have been studied in an optically accessible internal combustion engine. High-speed optical imaging measurements were applied over a range of ambient conditions, fuel types, and injection parameters. The optical data demonstrate that during the early part of the injection, while the liquid core of the jet is disintegrating, penetration is functionally linked to the orifice exit velocity up until a downstream distance hypothesized to be the jet breakup length. The jets then transition to a mixing dominated penetration behavior further downstream. Therefore, for cases that exhibit transient rate-of-injection (ROI) profiles, quasi-steady correlations for penetration have poor agreement with the empirical data. The lack of agreement between models using quasi-steady approximations and the high-speed experimental data, and the experimental evidence of liquid core physics impacting the transient jet penetration, motivated the development of a new 1-D model that integrates liquid core penetration physics and eliminates quasi-steady approximations. The new 1-D modeling methodology couples the transport equations for the evolution of the liquid core of the jet and the surrounding sheath of droplets resulting from breakup. The results of the model are validated against the aforementioned optical transient jet measurements. Finally, experimental results for two jet fuels and a diesel fuel are studied with the aid of the model. Differences in fuel properties cause the diesel fuel jet to transition from an incomplete spray to a complete spray later than the jet fuels during the transient injection process. Increasing ambient density causes the transition to happen earlier during the injection transient for all three fuels. The ignition delay and liftoff length appeared to be relatively unaffected by the late transition from incomplete to complete spray at low ambient density and low injection

  7. An alternative to computing grey-scale mathematical morphological operations and its optical implementation

    NASA Astrophysics Data System (ADS)

    Liang, Feng; Liu, Liren; Wang, Binquan; Wang, Zhijiang

    1994-12-01

    An alternative to the umbra definition on grey-scale mathematical morphology is proposed in this paper, which uses the top-surface set instead of the umbra to represent grey-scale structuring element. This algorithm greatly decreases the neighborhood connections for the binary morphological operation transformed from a grey-scale morphological operation. An optical incoherent correlator architecture with threshold device is developed to carry out the suggested algorithm, while a spatial digital coding method is used to represent input 3D binary data in a 2D arrangement. Experimental results are demonstrated too.

  8. Computer-aided analysis of nonequilibrium optical-phonon effects in nanoscale n-GaAs devices and structures

    NASA Astrophysics Data System (ADS)

    Paulavicius, Gediminas

    1998-12-01

    We have elaborated reliable computer-aided models of carrier and phonon systems in GaAs low dimensional structures. Nonequilibrium phonon effects on coupled electron-phonon relaxation and transport in specific GaAs/AlGaAs-based quantum devices and structures have been studied by the simulation techniques developed. We have found that for low electron concentrations in GaAs quantum wells the hot optical-phonon distribution reflects the main features of the "parental" carrier distribution. However, hot-phonon feedback in the electron subsystem is negligible in this case. For high carrier concentrations in the well structures, enhanced phonon interactions with the confined electron subsystem result in an isotropic phonon distribution. In this case, nonequilibrium optical phonons lead to an increase in the mean electron energy and a reduction in the carrier drift velocity. We have simulated kinetics of electron runaway from GaAs quantum wires in the 0optical phonons lead to significant electron escape from the potential well, even at relatively low electric fields. We have analyzed the influence of hot-phonon effects on coupled electron-phonon system relaxation dynamics in an AlGaAs/GaAs quantum cascade laser structure at 10 K. We have investigated in detail the possibility of increasing the effective lifetime of carriers in the upper lasing subband--and the consequent lowering of the lasing threshold currents-as a result of carrier return there from the lower level by means of induced hot optical-phonon reabsorption. Unfortunately, the simulation results reveal that under realistic conditions, the complete role of hot phonons is the opposite; indeed, they cause substantial electron heating in the subbands and significant induced optical-phonon emission. Both of these phenomena reduce the electron population inversion

  9. Computational fluid dynamics assisted characterization of parafoveal hemodynamics in normal and diabetic eyes using adaptive optics scanning laser ophthalmoscopy.

    PubMed

    Lu, Yang; Bernabeu, Miguel O; Lammer, Jan; Cai, Charles C; Jones, Martin L; Franco, Claudio A; Aiello, Lloyd Paul; Sun, Jennifer K

    2016-12-01

    Diabetic retinopathy (DR) is the leading cause of visual loss in working-age adults worldwide. Previous studies have found hemodynamic changes in the diabetic eyes, which precede clinically evident pathological alterations of the retinal microvasculature. There is a pressing need for new methods to allow greater understanding of these early hemodynamic changes that occur in DR. In this study, we propose a noninvasive method for the assessment of hemodynamics around the fovea (a region of the eye of paramount importance for vision). The proposed methodology combines adaptive optics scanning laser ophthalmoscopy and computational fluid dynamics modeling. We compare results obtained with this technique with in vivo measurements of blood flow based on blood cell aggregation tracking. Our results suggest that parafoveal hemodynamics, such as capillary velocity, wall shear stress, and capillary perfusion pressure can be noninvasively and reliably characterized with this method in both healthy and diabetic retinopathy patients.

  10. Computational fluid dynamics assisted characterization of parafoveal hemodynamics in normal and diabetic eyes using adaptive optics scanning laser ophthalmoscopy

    PubMed Central

    Lu, Yang; Bernabeu, Miguel O.; Lammer, Jan; Cai, Charles C.; Jones, Martin L.; Franco, Claudio A.; Aiello, Lloyd Paul; Sun, Jennifer K.

    2016-01-01

    Diabetic retinopathy (DR) is the leading cause of visual loss in working-age adults worldwide. Previous studies have found hemodynamic changes in the diabetic eyes, which precede clinically evident pathological alterations of the retinal microvasculature. There is a pressing need for new methods to allow greater understanding of these early hemodynamic changes that occur in DR. In this study, we propose a noninvasive method for the assessment of hemodynamics around the fovea (a region of the eye of paramount importance for vision). The proposed methodology combines adaptive optics scanning laser ophthalmoscopy and computational fluid dynamics modeling. We compare results obtained with this technique with in vivo measurements of blood flow based on blood cell aggregation tracking. Our results suggest that parafoveal hemodynamics, such as capillary velocity, wall shear stress, and capillary perfusion pressure can be noninvasively and reliably characterized with this method in both healthy and diabetic retinopathy patients. PMID:28078170

  11. Application of color image processing and low-coherent optical computer tomography in evaluation of adhesive interfaces of dental restorations

    NASA Astrophysics Data System (ADS)

    Bessudnova, Nadezda O.; Shlyapnikova, Olga A.; Venig, Sergey B.; Genina, Elina A.; Sadovnikov, Alexandr V.

    2015-03-01

    Durability of bonded interfaces between dentin and a polymer material in resin-based composite restorations remains a clinical dentistry challenge. In the present study the evolution of bonded interfaces in biological active environment is estimated in vivo. A novel in vivo method of visual diagnostics that involves digital processing of color images of composite restorations and allows the evaluation of adhesive interface quality over time, has been developed and tested on a group of volunteers. However, the application of the method is limited to the analysis of superficial adhesive interfaces. Low-coherent optical computer tomography (OCT) has been tested as a powerful non-invasive tool for in vivo, in situ clinical diagnostics of adhesive interfaces over time. In the long-term perspective adhesive interface monitoring using standard methods of clinical diagnostics along with colour image analysis and OCT could make it possible to objectivise and prognosticate the clinical longevity of composite resin-based restorations with adhesive interfaces.

  12. Computed tomography and optical remote sensing: Development for the study of indoor air pollutant transport and dispersion

    SciTech Connect

    Drescher, Anushka Christina

    1995-06-01

    This thesis investigates the mixing and dispersion of indoor air pollutants under a variety of conditions using standard experimental methods. It also extensively tests and improves a novel technique for measuring contaminant concentrations that has the potential for more rapid, non-intrusive measurements with higher spatial resolution than previously possible. Experiments conducted in a sealed room support the hypothesis that the mixing time of an instantaneously released tracer gas is inversely proportional to the cube root of the mechanical power transferred to the room air. One table-top and several room-scale experiments are performed to test the concept of employing optical remote sensing (ORS) and computed tomography (CT) to measure steady-state gas concentrations in a horizontal plane. Various remote sensing instruments, scanning geometries and reconstruction algorithms are employed. Reconstructed concentration distributions based on existing iterative CT techniques contain a high degree of unrealistic spatial variability and do not agree well with simultaneously gathered point-sample data.

  13. Application of optical distributed sensing and computation to control of large space structures

    NASA Technical Reports Server (NTRS)

    Balakrishnan, A. V.

    1992-01-01

    A real time holographic sensing technique is introduced and its advantages are investigated from the filtering and control point of view. A feature of holographic sensing is its capability to make distributed measurements of the position and velocity of moving objects, such as a vibrating flexible space structure. This work is based upon the distributed parameter models of linear time invariant systems, particularly including the linear oscillator equations describing the vibration of large flexible space structures. The general conclusion is that application of optical distributed sensors bring gains in the situation where Kalman filtering is necessary for state estimation. In this case, both steady state and transient filtering error covariance become smaller. This in turn results in smaller cost in the LQG problem.

  14. An infrastructure with a unified control plane to integrate IP into optical metro networks to provide flexible and intelligent bandwidth on demand for cloud computing

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Hall, Trevor

    2012-12-01

    The Internet is entering an era of cloud computing to provide more cost effective, eco-friendly and reliable services to consumer and business users and the nature of the Internet traffic will undertake a fundamental transformation. Consequently, the current Internet will no longer suffice for serving cloud traffic in metro areas. This work proposes an infrastructure with a unified control plane that integrates simple packet aggregation technology with optical express through the interoperation between IP routers and electrical traffic controllers in optical metro networks. The proposed infrastructure provides flexible, intelligent, and eco-friendly bandwidth on demand for cloud computing in metro areas.

  15. Light-field-characterization in a continuous hydrogen-producing photobioreactor by optical simulation and computational fluid dynamics.

    PubMed

    Krujatz, Felix; Illing, Rico; Krautwer, Tobias; Liao, Jing; Helbig, Karsten; Goy, Katharina; Opitz, Jörg; Cuniberti, Gianaurelio; Bley, Thomas; Weber, Jost

    2015-12-01

    Externally illuminated photobioreactors (PBRs) are widely used in studies on the use of phototrophic microorganisms as sources of bioenergy and other photobiotechnology research. In this work, straightforward simulation techniques were used to describe effects of varying fluid flow conditions in a continuous hydrogen-producing PBR on the rate of photofermentative hydrogen production (rH2 ) by Rhodobacter sphaeroides DSM 158. A ZEMAX optical ray tracing simulation was performed to quantify the illumination intensity reaching the interior of the cylindrical PBR vessel. 24.2% of the emitted energy was lost through optical effects, or did not reach the PBR surface. In a dense culture of continuously producing bacteria during chemostatic cultivation, the illumination intensity became completely attenuated within the first centimeter of the PBR radius as described by an empirical three-parametric model implemented in Mathcad. The bacterial movement in chemostatic steady-state conditions was influenced by varying the fluid Reynolds number. The "Computational Fluid Dynamics" and "Particle Tracing" tools of COMSOL Multiphysics were used to visualize the fluid flow pattern and cellular trajectories through well-illuminated zones near the PBR periphery and dark zones in the center of the PBR. A moderate turbulence (Reynolds number = 12,600) and fluctuating illumination of 1.5 Hz were found to yield the highest continuous rH2 by R. sphaeroides DSM 158 (170.5 mL L(-1) h(-1) ) in this study.

  16. Real-Time Display Of 3-D Computed Holograms By Scanning The Image Of An Acousto-Optic Modulator

    NASA Astrophysics Data System (ADS)

    Kollin, Joel S.; Benton, Stephen A.; Jepsen, Mary Lou

    1989-10-01

    The invention of holography has sparked hopes for a three-dimensional electronic imaging systems analogous to television. Unfortunately, the extraordinary spatial detail of ordinary holographic recordings requires unattainable bandwidth and display resolution for three-dimensional moving imagery, effectively preventing their commercial development. However, the essential bandwidth of holographic images can be reduced enough to permit their transmission through fiber optic or coaxial cable, and the required resolution or space-bandwidth product of the display can be obtained by raster scanning the image of a commercially available acousto-optic modulator. No film recording or other photographic intermediate step is necessary as the projected modulator image is viewed directly. The design and construction of a working demonstration of the principles involved is also presented along with a discussion of engineering considerations in the system design. Finally, the theoretical and practical limitations of the system are addressed in the context of extending the system to real-time transmission of moving holograms synthesized from views of real and computer-generated three-dimensional scenes.

  17. Non-sequential optimization technique for a computer controlled optical surfacing process using multiple tool influence functions.

    PubMed

    Kim, Dae Wook; Kim, Sug-Whan; Burge, James H

    2009-11-23

    Optical surfaces can be accurately figured by computer controlled optical surfacing (CCOS) that uses well characterized sub-diameter polishing tools driven by numerically controlled (NC) machines. The motion of the polishing tool is optimized to vary the dwell time of the polisher on the workpiece according to the desired removal and the calibrated tool influence function (TIF). Operating CCOS with small and very well characterized TIF achieves excellent performance, but it takes a long time. This overall polishing time can be reduced by performing sequential polishing runs that start with large tools and finish with smaller tools. In this paper we present a variation of this technique that uses a set of different size TIFs, but the optimization is performed globally - i.e. simultaneously optimizing the dwell times and tool shapes for the entire set of polishing runs. So the actual polishing runs will be sequential, but the optimization is comprehensive. As the optimization is modified from the classical method to the comprehensive non-sequential algorithm, the performance improvement is significant. For representative polishing runs we show figuring efficiency improvement from approximately 88% to approximately 98% in terms of residual RMS (root-mean-square) surface error and from approximately 47% to approximately 89% in terms of residual RMS slope error.

  18. Vibrational spectroscopic studies and DFT computation of the nonlinear optical molecule L-Valinium formate

    NASA Astrophysics Data System (ADS)

    Joselin Beaula, T.; Manimaran, D.; Hubert Joe, I.; Rastogi, V. K.; Bena Jothy, V.

    The Fourier Transform Infrared and Raman spectra of the L-Valinium formate have been recorded and analyzed. The assignments of the bands of the vibrational spectra have been carried out with the aid of Normal Coordinate Analysis following the calculated quantum mechanical force field methodology. Optimized geometry of the molecule has computed using of Density Functional Theory method. Natural Bond Orbital Analysis, Mulliken’s net charges and the atomic natural charges are also predicted. HOMO and LUMO energy gap value suggest the possibility of charge transfer within the molecule. The thermodynamic properties at different temperatures are also calculated.

  19. Effective method to compute vibrationally resolved optical spectra of large molecules at finite temperature in the gas phase and in solution.

    PubMed

    Santoro, Fabrizio; Lami, Alessandro; Improta, Roberto; Barone, Vincenzo

    2007-05-14

    The authors present a new method for the computation of vibrationally resolved optical spectra of large molecules, including the Duschinsky rotation of the normal modes and the effect of thermal excitation. The method automatically selects the relevant vibronic contributions to the spectrum, independently of their frequency, and it is able to provide fully converged spectra with moderate computational times, both in vacuo and in solution. By describing the electronic states in the frame of the density functional theory and its time-dependent extension, they computed the room temperature absorption spectra of coumarin C153 and trans-stilbene in cyclohexane and the phosphorescence spectrum of porphyrazine in gas phase, showing that the method is fast and efficient. The comparison with experiment for trans-stilbene and coumarin C153 is very satisfactory, confirming the progress made toward a reliable method for the computation and interpretation for the optical spectra of large molecules.

  20. Quantum Computation by Optically Coupled Steady Atoms/Quantum-Dots Inside a Quantum Cavity

    NASA Technical Reports Server (NTRS)

    Pradhan, P.; Wang, K. L.; Roychowdhury, V. P.; Anantram, M. P.; Mor, T.; Saini, Subhash (Technical Monitor)

    1999-01-01

    We present a model for quantum computation using $n$ steady 3-level atoms kept inside a quantum cavity, or using $n$ quantum-dots (QDs) kept inside a quantum cavity. In this model one external laser is pointed towards all the atoms/QDs, and $n$ pairs of electrodes are addressing the atoms/QDs, so that each atom is addressed by one pair. The energy levels of each atom/QD are controlled by an external Stark field given to the atom/QD by its external pair of electrodes. Transition between two energy levels of an individual atom/ QD are controlled by the voltage on its electrodes, and by the external laser. Interactions between two atoms/ QDs are performed with the additional help of the cavity mode (using on-resonance condition). Laser frequency, cavity frequency, and energy levels are far off-resonance most of the time, and they are brought to the resonance (using the Stark effect) only at the time of operations. Steps for a controlled-NOT gate between any two atoms/QDs have been described for this model. Our model demands some challenging technological efforts, such as manufacturing single-electron QDs inside a cavity. However, it promises big advantages over other existing models which are currently implemented, and might enable a much easier scale-up, to compute with many more qubits.

  1. L-asparagine crystals with wide gap semiconductor features: Optical absorption measurements and density functional theory computations

    SciTech Connect

    Zanatta, G.; Gottfried, C.; Silva, A. M.; Caetano, E. W. S.; Sales, F. A. M.; Freire, V. N.

    2014-03-28

    Results of optical absorption measurements are presented together with calculated structural, electronic, and optical properties for the anhydrous monoclinic L-asparagine crystal. Density functional theory (DFT) within the generalized gradient approximation (GGA) including dispersion effects (TS, Grimme) was employed to perform the calculations. The optical absorption measurements revealed that the anhydrous monoclinic L-asparagine crystal is a wide band gap material with 4.95 eV main gap energy. DFT-GGA+TS simulations, on the other hand, produced structural parameters in very good agreement with X-ray data. The lattice parameter differences Δa, Δb, Δc between theory and experiment were as small as 0.020, 0.051, and 0.022 Å, respectively. The calculated band gap energy is smaller than the experimental data by about 15%, with a 4.23 eV indirect band gap corresponding to Z → Γ and Z → β transitions. Three other indirect band gaps of 4.30 eV, 4.32 eV, and 4.36 eV are assigned to α3 → Γ, α1 → Γ, and α2 → Γ transitions, respectively. Δ-sol computations, on the other hand, predict a main band gap of 5.00 eV, just 50 meV above the experimental value. Electronic wavefunctions mainly originating from O 2p–carboxyl, C 2p–side chain, and C 2p–carboxyl orbitals contribute most significantly to the highest valence and lowest conduction energy bands, respectively. By varying the lattice parameters from their converged equilibrium values, we show that the unit cell is less stiff along the b direction than for the a and c directions. Effective mass calculations suggest that hole transport behavior is more anisotropic than electron transport, but the mass values allow for some charge mobility except along a direction perpendicular to the molecular layers of L-asparagine which form the crystal, so anhydrous monoclinic L-asparagine crystals could behave as wide gap semiconductors. Finally, the calculations point to a high degree of optical

  2. L-Asparagine crystals with wide gap semiconductor features: optical absorption measurements and density functional theory computations.

    PubMed

    Zanatta, G; Gottfried, C; Silva, A M; Caetano, E W S; Sales, F A M; Freire, V N

    2014-03-28

    Results of optical absorption measurements are presented together with calculated structural, electronic, and optical properties for the anhydrous monoclinic L-asparagine crystal. Density functional theory (DFT) within the generalized gradient approximation (GGA) including dispersion effects (TS, Grimme) was employed to perform the calculations. The optical absorption measurements revealed that the anhydrous monoclinic L-asparagine crystal is a wide band gap material with 4.95 eV main gap energy. DFT-GGA+TS simulations, on the other hand, produced structural parameters in very good agreement with X-ray data. The lattice parameter differences Δa, Δb, Δc between theory and experiment were as small as 0.020, 0.051, and 0.022 Å, respectively. The calculated band gap energy is smaller than the experimental data by about 15%, with a 4.23 eV indirect band gap corresponding to Z → Γ and Z → β transitions. Three other indirect band gaps of 4.30 eV, 4.32 eV, and 4.36 eV are assigned to α3 → Γ, α1 → Γ, and α2 → Γ transitions, respectively. Δ-sol computations, on the other hand, predict a main band gap of 5.00 eV, just 50 meV above the experimental value. Electronic wavefunctions mainly originating from O 2p-carboxyl, C 2p-side chain, and C 2p-carboxyl orbitals contribute most significantly to the highest valence and lowest conduction energy bands, respectively. By varying the lattice parameters from their converged equilibrium values, we show that the unit cell is less stiff along the b direction than for the a and c directions. Effective mass calculations suggest that hole transport behavior is more anisotropic than electron transport, but the mass values allow for some charge mobility except along a direction perpendicular to the molecular layers of L-asparagine which form the crystal, so anhydrous monoclinic L-asparagine crystals could behave as wide gap semiconductors. Finally, the calculations point to a high degree of optical

  3. Optical coherence tomography (OCT) imaging and computer aided diagnosis of human cervical tissue specimens

    NASA Astrophysics Data System (ADS)

    Bazant-Hegemark, F.; Stone, N.; Read, M. D.; McCarthy, K.; Wang, R. K.

    2007-07-01

    The keyword for management of cervical cancer is prevention. The present program within the UK, the 'National Health Service (NHS) cervical screening programme' (NHSCSP), is based on cytology. Although the program has reduced the incidence of cervical cancer, this program requires patient follow ups and relies on diagnostic biopsying. There is potential for reducing costs and workload within the NHS, and relieving anxiety of patients. In this study, Optical Coherence Tomography (OCT) was investigated for its capability to improve this situation. Our time domain bench top system used a superluminescent diode (Superlum), centre wave length ~1.3 μm, resolution (air) ~15 μm. Tissue samples were obtained according to the ethics approval by Gloucestershire LREC, Nr. 05/Q2005/123. 1387 images of 199 participants have been compared with histopathology results and categorized accordingly. Our OCT images do not reach the clarity and resolution of histopathology. Further, establishing and recognizing features of diagnostic significance seems difficult. Automated classification would allow one to take decision-making to move from the subjective appraisal of a physician to an objective assessment. Hence we investigated a classification algorithm for its ability in recognizing pre-cancerous stages from OCT images. The initial results show promise.

  4. Supramolecular complex coupled to a metal nanoparticle: computational studies on the optical absorption.

    PubMed

    Zelinskyy, Yaroslav; Zhang, Yuan; May, Volkhard

    2012-11-26

    Absorption spectra of a supramolecular complex (SC) placed in the proximity of a spherical metal nanoparticle (MNP) are computed. A description of the absorption is used that is based on a density matrix propagation. The applied density matrix theory starts from a microscopic model including the Coulomb interaction between the SC and the MNP. This interaction is dominated by an energy exchange coupling between the excitations of the SC and the multipolar excitations of the MNP. Its nonperturbative consideration results in a shift and a broadening of all Frenkel-exciton levels as well as an oscillator strength change. If a J-aggregate type SC near a MNP is considered, all exciton levels strongly contribute to the absorption what is in contrast to the isolated SC.

  5. X-ray refraction-contrast computed tomography images using dark-field imaging optics

    SciTech Connect

    Sunaguchi, Naoki; Yuasa, Tetsuya; Huo, Qingkai; Ichihara, Shu; Ando, Masami

    2010-10-11

    If an x-ray beam containing internal information derived from sample soft tissue is incident upon a Laue-case analyzer, the beam will subsequently split into a forwardly diffracted beam and a separate diffracted beam. Using these beams acquired simultaneously, a refraction-contrast computed tomography (CT) imaging system for biomedical use with lower radiation dose can be easily realized, and has a high depicting capability on the soft tissues compared with conventional x-ray CT based on absorption contrast principles. In this paper, we propose an imaging system using dark-field imaging for CT measurement based on a tandem system of Bragg- and Laue-case crystals with two two-dimensional detectors, along with a data-processing method to extract information on refraction from the measured entangled intensities by use of rocking curve fitting with polynomial functions. Reconstructed images of soft tissues are presented and described.

  6. Optical computing and neural networks; Proceedings of the Meeting, National Chiao Tung Univ., Hsinchu, Taiwan, Dec. 16, 17, 1992

    NASA Technical Reports Server (NTRS)

    Hsu, Ken-Yuh (Editor); Liu, Hua-Kuang (Editor)

    1992-01-01

    The present conference discusses optical neural networks, photorefractive nonlinear optics, optical pattern recognition, digital and analog processors, and holography and its applications. Attention is given to bifurcating optical information processing, neural structures in digital halftoning, an exemplar-based optical neural net classifier for color pattern recognition, volume storage in photorefractive disks, and microlaser-based compact optical neuroprocessors. Also treated are the optical implementation of a feature-enhanced optical interpattern-associative neural network model and its optical implementation, an optical pattern binary dual-rail logic gate module, a theoretical analysis for holographic associative memories, joint transform correlators, image addition and subtraction via the Talbot effect, and optical wavelet-matched filters. (No individual items are abstracted in this volume)

  7. Automated X-ray and Optical Analysis of the Virtual Observatory and Grid Computing

    NASA Technical Reports Server (NTRS)

    Ptak, A.; Krughoff, S.; Connolly, A.

    2011-01-01

    We are developing a system to combine the Web Enabled Source Identification with X-Matching (WESIX) web service, which emphasizes source detection on optical images,with the XAssist program that automates the analysis of X-ray data. XAssist is continuously processing archival X-ray data in several pipelines. We have established a workflow in which FITS images and/or (in the case of X ray data) an X-ray field can be input to WESIX. Intelligent services return available data (if requested fields have been processed) or submit job requests to a queue to be performed asynchronously. These services will be available via web services (for non-interactive use by Virtual Observatory portals and applications) and through web applications (written in the Django web application framework). We are adding web services for specific XAssist functionality such as determining .the exposure and limiting flux for a given position on the sky and extracting spectra and images for a given region. We are improving the queuing system in XAssist to allow for "watch lists" to be specified by users, and when X-ray fields in a user's watch list become publicly available they will be automatically added to the queue. XAssist is being expanded to be used as a survey planning 1001 when coupled with simulation software, including functionality for NuStar, eRosita, IXO, and the Wide Field Xray Telescope (WFXT), as part of an end to end simulation/analysis system. We are also investigating the possibility of a dedicated iPhone/iPad app for querying pipeline data, requesting processing, and administrative job control.

  8. Development of a Computer Architecture to Support the Optical Plume Anomaly Detection (OPAD) System

    NASA Technical Reports Server (NTRS)

    Katsinis, Constantine

    1996-01-01

    The NASA OPAD spectrometer system relies heavily on extensive software which repetitively extracts spectral information from the engine plume and reports the amounts of metals which are present in the plume. The development of this software is at a sufficiently advanced stage where it can be used in actual engine tests to provide valuable data on engine operation and health. This activity will continue and, in addition, the OPAD system is planned to be used in flight aboard space vehicles. The two implementations, test-stand and in-flight, may have some differing requirements. For example, the data stored during a test-stand experiment are much more extensive than in the in-flight case. In both cases though, the majority of the requirements are similar. New data from the spectrograph is generated at a rate of once every 0.5 sec or faster. All processing must be completed within this period of time to maintain real-time performance. Every 0.5 sec, the OPAD system must report the amounts of specific metals within the engine plume, given the spectral data. At present, the software in the OPAD system performs this function by solving the inverse problem. It uses powerful physics-based computational models (the SPECTRA code), which receive amounts of metals as inputs to produce the spectral data that would have been observed, had the same metal amounts been present in the engine plume. During the experiment, for every spectrum that is observed, an initial approximation is performed using neural networks to establish an initial metal composition which approximates as accurately as possible the real one. Then, using optimization techniques, the SPECTRA code is repetitively used to produce a fit to the data, by adjusting the metal input amounts until the produced spectrum matches the observed one to within a given level of tolerance. This iterative solution to the original problem of determining the metal composition in the plume requires a relatively long period of time

  9. Experiments, Computation, and Modeling for Temperature Dependence of Absorption, Scattering, Reflection, Transmission, and Index of Refraction of Optical Radiation in Biological Tissues

    DTIC Science & Technology

    2006-12-01

    The objective of this research was to systematically measure the temperature dependence of optical properties of various bovine eye tissues at...elevated temperatures (above body temperature) using different experimental and computational techniques. The temperature dependence of absorption and...and total transmittance, it was determined that any temperature dependence of the diffuse reflectance and total transmittance could not be discerned

  10. Trianguleniums as Optical Probes for G‐Quadruplexes: A Photophysical, Electrochemical, and Computational Study

    PubMed Central

    Shivalingam, Arun; Vyšniauskas, Aurimas; Albrecht, Tim; White, Andrew J. P.

    2016-01-01

    Abstract Nucleic acids can adopt non‐duplex topologies, such as G‐quadruplexes in vitro. Yet it has been challenging to establish their existence and function in vivo due to a lack of suitable tools. Recently, we identified the triangulenium compound DAOTA‐M2 as a unique fluorescence probe for such studies. This probe's emission lifetime is highly dependent on the topology of the DNA it interacts with opening up the possibility of carrying out live‐cell imaging studies. Herein, we describe the origin of its fluorescence selectivity for G‐quadruplexes. Cyclic voltammetry predicts that the appended morpholino groups can act as intra‐ molecular photo‐induced electron transfer (PET) quenchers. Photophysical studies show that a delicate balance between this effect and inter‐molecular PET with nucleobases is key to the overall fluorescence enhancement observed upon nucleic acid binding. We utilised computational modelling to demonstrate a conformational dependence of intra‐molecular PET. Finally, we performed orthogonal studies with a triangulenium compound, in which the morpholino groups were removed, and demonstrated that this change inverts triangulenium fluorescence selectivity from G‐quadruplex to duplex DNA, thus highlighting the importance of fine tuning the molecular structure not only for target affinity, but also for fluorescence response. PMID:26880483

  11. Computational Nanophotonics: modeling optical interactions and transport in tailored nanosystem architectures

    SciTech Connect

    Schatz, George; Ratner, Mark

    2014-02-27

    This report describes research by George Schatz and Mark Ratner that was done over the period 10/03-5/09 at Northwestern University. This research project was part of a larger research project with the same title led by Stephen Gray at Argonne. A significant amount of our work involved collaborations with Gray, and there were many joint publications as summarized later. In addition, a lot of this work involved collaborations with experimental groups at Northwestern, Argonne, and elsewhere. The research was primarily concerned with developing theory and computational methods that can be used to describe the interaction of light with noble metal nanoparticles (especially silver) that are capable of plasmon excitation. Classical electrodynamics provides a powerful approach for performing these studies, so much of this research project involved the development of methods for solving Maxwell’s equations, including both linear and nonlinear effects, and examining a wide range of nanostructures, including particles, particle arrays, metal films, films with holes, and combinations of metal nanostructures with polymers and other dielectrics. In addition, our work broke new ground in the development of quantum mechanical methods to describe plasmonic effects based on the use of time dependent density functional theory, and we developed new theory concerned with the coupling of plasmons to electrical transport in molecular wire structures. Applications of our technology were aimed at the development of plasmonic devices as components of optoelectronic circuits, plasmons for spectroscopy applications, and plasmons for energy-related applications.

  12. One-way quantum computing with arbitrarily large time-frequency continuous-variable cluster states from a single optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Alexander, Rafael N.; Wang, Pei; Sridhar, Niranjan; Chen, Moran; Pfister, Olivier; Menicucci, Nicolas C.

    2016-09-01

    One-way quantum computing is experimentally appealing because it requires only local measurements on an entangled resource called a cluster state. Record-size, but nonuniversal, continuous-variable cluster states were recently demonstrated separately in the time and frequency domains. We propose to combine these approaches into a scalable architecture in which a single optical parametric oscillator and simple interferometer entangle up to (3 ×103 frequencies) × (unlimited number of temporal modes) into a computationally universal continuous-variable cluster state. We introduce a generalized measurement protocol to enable improved computational performance on this entanglement resource.

  13. Numerical simulation of a novel all-optical flip-flop based on a chirped nonlinear distributed feedback semiconductor laser structure using GPGPU computing

    NASA Astrophysics Data System (ADS)

    Zoweil, H.

    2015-05-01

    A novel all-optical flip-flop based on a chirped nonlinear distributed feedback laser structure is proposed. The flip-flop does not require a holding beam. The optical gain is provided by a current injection into an active layer. The nonlinear wave-guiding layer consists of a chirped phase shifted grating accompanied with a negative nonlinear refractive index coefficient that increases in magnitude along the wave-guide. In the 'OFF' state, the chirped grating does not provide the required optical feedback to start lasing. An optical pulse switches the device 'ON' by reducing the chirp due to the negative nonlinear refractive index coefficient. The reduced chirp grating provides enough feedback to sustain a laser mode. The device is switched 'OFF' by cross gain modulation. GPGPU computing allows for long simulation time of multiple SET-RESET operations. The 'ON/OFF' transitions delays are in nanoseconds time scale.

  14. Should computed tomographic colonography replace optical colonoscopy in screening for colorectal cancer?

    PubMed

    Veerappan, Ganesh R; Cash, Brooks D

    2009-04-01

    Clinical evidence amassed over the last several decades indicates that routine colorectal cancer (CRC) screening, compared to no screening, detects CRC at an earlier stage, reduces the incidence of CRC or the progression early CRC through polypectomy, and reduces CRC mortality. Computed tomographic colonography (CTC) is a minimally invasive, structural evaluation of the entire colorectum that has recently been advocated by multiple American professional medical societies as an effective alternative for CRC screening. The potential advantages of CTC, including rapid image acquisition and processing, non-invasiveness, and decreased procedural risks of perforation, bleeding, and sedation complications may serve to improve the low rates of colorectal cancer screening that are currently observed in our society. Several large studies of CTC as a CRC screening test have reported excellent results but have been criticized because of the expertise of CTC interpreters participating in those trials. As a response to these criticisms, the long-awaited results of the American College of Radiology Imaging Network (ACRIN) National CT Colonography Trial were recently published. The purpose of this study was to assess the accuracy of CTC in a "community based" environment to determine if previous results obtained at expert sites could be replicated. All CTC were confirmed and compared to conventional colonoscopy, the gold-standard colorectal cancer screening test. For polyps >10 mm, the results obtained in the ACRIN trial were comparable to previous studies with a mean CTC sensitivity of 90% and a mean CTC specificity of 86%. The sensitivity of CTC fell to 78% for lesions >6 mm, a value that some studies have suggested is comparable to the detection rate of conventional colonoscopy. This study adds to the body of literature regarding the efficacy of CTC and will likely be cited by many as evidence supporting CTC as an acceptable CRC screening test, in the same league as colonoscopy

  15. Optical Micromachining

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Under an SBIR (Small Business Innovative Research) with Marshall Space Flight Center, Potomac Photonics, Inc., constructed and demonstrated a unique tool that fills a need in the area of diffractive and refractive micro-optics. It is an integrated computer-aided design and computer-aided micro-machining workstation that will extend the benefits of diffractive and micro-optic technology to optical designers. Applications of diffractive optics include sensors and monitoring equipment, analytical instruments, and fiber optic distribution and communication. The company has been making diffractive elements with the system as a commercial service for the last year.

  16. Quantitative computed tomography (QCT) as a radiology reporting tool by using optical character recognition (OCR) and macro program.

    PubMed

    Lee, Young Han; Song, Ho-Taek; Suh, Jin-Suck

    2012-12-01

    The objectives are (1) to introduce a new concept of making a quantitative computed tomography (QCT) reporting system by using optical character recognition (OCR) and macro program and (2) to illustrate the practical usages of the QCT reporting system in radiology reading environment. This reporting system was created as a development tool by using an open-source OCR software and an open-source macro program. The main module was designed for OCR to report QCT images in radiology reading process. The principal processes are as follows: (1) to save a QCT report as a graphic file, (2) to recognize the characters from an image as a text, (3) to extract the T scores from the text, (4) to perform error correction, (5) to reformat the values into QCT radiology reporting template, and (6) to paste the reports into the electronic medical record (EMR) or picture archiving and communicating system (PACS). The accuracy test of OCR was performed on randomly selected QCTs. QCT as a radiology reporting tool successfully acted as OCR of QCT. The diagnosis of normal, osteopenia, or osteoporosis is also determined. Error correction of OCR is done with AutoHotkey-coded module. The results of T scores of femoral neck and lumbar vertebrae had an accuracy of 100 and 95.4 %, respectively. A convenient QCT reporting system could be established by utilizing open-source OCR software and open-source macro program. This method can be easily adapted for other QCT applications and PACS/EMR.

  17. Storage and retrieval of SNOP-coded pathologic diagnoses using offsite computing and optical character recognizing systems.

    PubMed

    Cechner, R L; Carter, J R

    1976-05-01

    A computerized cross-reference system for retrieving autopsy and surgical pathology cases on the basis of case number or diagnosis has been implemented. The system achieves economy and flexibility by using offsite computer service bureaus for job production, eliminating the need for expensive onsite equipment. Coded diagnoses may be typed using the OCR (Optical Character Recognition) font simultaneously with or separately from the clinical documentation. The flexibility of new OCR equipment permits production of machine-readable code sheets with an ordinary pencil and completely eliminates the need for typing. The system produces year-to-date books that list all diagnoses, on an accumulating basis, in alphabetic order by SNOP* topology, morphology, etiology and function, and will be compatible with SNOMed. Because all data are stored on magnetic tape, they may be manipulated and retrieved as desired through user programming. The initial setup cost was dollar 1,000 for programming and testing, and production runs and all report printing cost about dollar 1,000 per year (autopsies and surgical pathology cases), which is about 1.1 cents per diagnosis.

  18. Assessment of natural enamel lesions with optical coherence tomography in comparison with microfocus x-ray computed tomography

    PubMed Central

    Espigares, Jorge; Sadr, Alireza; Hamba, Hidenori; Shimada, Yasushi; Otsuki, Masayuki; Tagami, Junji; Sumi, Yasunori

    2015-01-01

    Abstract. A technology to characterize early enamel lesions is needed in dentistry. Optical coherence tomography (OCT) is a noninvasive method that provides high-resolution cross-sectional images. The aim of this study is to compare OCT with microfocus x-ray computed tomography (μCT) for assessment of natural enamel lesions in vitro. Ten human teeth with visible white spot-like changes on the enamel smooth surface and no cavitation (ICDAS code 2) were subjected to imaging by μCT (SMX-100CT, Shimadzu) and 1300-nm swept-source OCT (Dental SS-OCT, Panasonic Health Care). In μCT, the lesions appeared as radiolucent dark areas, while in SS-OCT, they appeared as areas of increased signal intensity beneath the surface. An SS-OCT attenuation coefficient based on Beer–Lambert law could discriminate lesions from sound enamel. Lesion depth ranged from 175 to 606  μm in SS-OCT. A correlation between μCT and SS-OCT was found regarding lesion depth (R=0.81, p<0.001) and also surface layer thickness (R=0.76, p<0.005). The images obtained clinically in real time using the dental SS-OCT system are suitable for the assessment of natural subsurface lesions and their surface layer, providing comparable images to a laboratory high-resolution μCT without the use of x-ray. PMID:26158079

  19. Evaluation of flow velocities after carotid artery stenting through split spectrum Doppler optical coherence tomography and computational fluid dynamics modeling

    PubMed Central

    Vuong, Barry; Genis, Helen; Wong, Ronnie; Ramjist, Joel; Jivraj, Jamil; Farooq, Hamza; Sun, Cuiru; Yang, Victor X.D.

    2014-01-01

    Hemodynamics plays a critical role in the development of atherosclerosis, specifically in regions of curved vasculature such as bifurcations exhibiting irregular blood flow profiles. Carotid atherosclerotic disease can be intervened by stent implantation, but this may result in greater alterations to local blood flow and consequently further complications. This study demonstrates the use of a variant of Doppler optical coherence tomography (DOCT) known as split spectrum DOCT (ssDOCT) to evaluate hemodynamic patterns both before and after stent implantation in the bifurcation junction in the internal carotid artery (ICA). Computational fluid dynamics (CFD) models were constructed to simulate blood velocity profiles and compared to the findings achieved through ssDOCT images. Both methods demonstrated noticeable alterations in hemodynamic patterns following stent implantation, with features such as slow velocity regions at the neck of the bifurcation and recirculation zones at the stent struts. Strong correlation between CFD models and ssDOCT images demonstrate the potential of ssDOCT imaging in the optimization of stent implantation in the clinical setting. PMID:25574447

  20. Evaluation of flow velocities after carotid artery stenting through split spectrum Doppler optical coherence tomography and computational fluid dynamics modeling.

    PubMed

    Vuong, Barry; Genis, Helen; Wong, Ronnie; Ramjist, Joel; Jivraj, Jamil; Farooq, Hamza; Sun, Cuiru; Yang, Victor X D

    2014-12-01

    Hemodynamics plays a critical role in the development of atherosclerosis, specifically in regions of curved vasculature such as bifurcations exhibiting irregular blood flow profiles. Carotid atherosclerotic disease can be intervened by stent implantation, but this may result in greater alterations to local blood flow and consequently further complications. This study demonstrates the use of a variant of Doppler optical coherence tomography (DOCT) known as split spectrum DOCT (ssDOCT) to evaluate hemodynamic patterns both before and after stent implantation in the bifurcation junction in the internal carotid artery (ICA). Computational fluid dynamics (CFD) models were constructed to simulate blood velocity profiles and compared to the findings achieved through ssDOCT images. Both methods demonstrated noticeable alterations in hemodynamic patterns following stent implantation, with features such as slow velocity regions at the neck of the bifurcation and recirculation zones at the stent struts. Strong correlation between CFD models and ssDOCT images demonstrate the potential of ssDOCT imaging in the optimization of stent implantation in the clinical setting.

  1. Assessment of natural enamel lesions with optical coherence tomography in comparison with microfocus x-ray computed tomography.

    PubMed

    Espigares, Jorge; Sadr, Alireza; Hamba, Hidenori; Shimada, Yasushi; Otsuki, Masayuki; Tagami, Junji; Sumi, Yasunori

    2015-01-01

    A technology to characterize early enamel lesions is needed in dentistry. Optical coherence tomography (OCT) is a noninvasive method that provides high-resolution cross-sectional images. The aim of this study is to compare OCT with microfocus x-ray computed tomography ([Formula: see text]) for assessment of natural enamel lesions in vitro. Ten human teeth with visible white spot-like changes on the enamel smooth surface and no cavitation (ICDAS code 2) were subjected to imaging by μCT (SMX-100CT, Shimadzu) and 1300-nm swept-source OCT (Dental SS-OCT, Panasonic Health Care). In [Formula: see text], the lesions appeared as radiolucent dark areas, while in SS-OCT, they appeared as areas of increased signal intensity beneath the surface. An SS-OCT attenuation coefficient based on Beer-Lambert law could discriminate lesions from sound enamel. Lesion depth ranged from 175 to [Formula: see text] in SS-OCT. A correlation between [Formula: see text] and SS-OCT was found regarding lesion depth ([Formula: see text], [Formula: see text]) and also surface layer thickness ([Formula: see text], [Formula: see text]). The images obtained clinically in real time using the dental SS-OCT system are suitable for the assessment of natural subsurface lesions and their surface layer, providing comparable images to a laboratory high-resolution [Formula: see text] without the use of x-ray.

  2. Development of a software interface for optical disk archival storage for a new life sciences flight experiments computer

    NASA Technical Reports Server (NTRS)

    Bartram, Peter N.

    1989-01-01

    The current Life Sciences Laboratory Equipment (LSLE) microcomputer for life sciences experiment data acquisition is now obsolete. Among the weaknesses of the current microcomputer are small memory size, relatively slow analog data sampling rates, and the lack of a bulk data storage device. While life science investigators normally prefer data to be transmitted to Earth as it is taken, this is not always possible. No down-link exists for experiments performed in the Shuttle middeck region. One important aspect of a replacement microcomputer is provision for in-flight storage of experimental data. The Write Once, Read Many (WORM) optical disk was studied because of its high storage density, data integrity, and the availability of a space-qualified unit. In keeping with the goals for a replacement microcomputer based upon commercially available components and standard interfaces, the system studied includes a Small Computer System Interface (SCSI) for interfacing the WORM drive. The system itself is designed around the STD bus, using readily available boards. Configurations examined were: (1) master processor board and slave processor board with the SCSI interface; (2) master processor with SCSI interface; (3) master processor with SCSI and Direct Memory Access (DMA); (4) master processor controlling a separate STD bus SCSI board; and (5) master processor controlling a separate STD bus SCSI board with DMA.

  3. Quantitative Assessment of Optical Coherence Tomography Imaging Performance with Phantom-Based Test Methods And Computational Modeling

    NASA Astrophysics Data System (ADS)

    Agrawal, Anant

    Optical coherence tomography (OCT) is a powerful medical imaging modality that uniquely produces high-resolution cross-sectional images of tissue using low energy light. Its clinical applications and technological capabilities have grown substantially since its invention about twenty years ago, but efforts have been limited to develop tools to assess performance of OCT devices with respect to the quality and content of acquired images. Such tools are important to ensure information derived from OCT signals and images is accurate and consistent, in order to support further technology development, promote standardization, and benefit public health. The research in this dissertation investigates new physical and computational models which can provide unique insights into specific performance characteristics of OCT devices. Physical models, known as phantoms, are fabricated and evaluated in the interest of establishing standardized test methods to measure several important quantities relevant to image quality. (1) Spatial resolution is measured with a nanoparticle-embedded phantom and model eye which together yield the point spread function under conditions where OCT is commonly used. (2) A multi-layered phantom is constructed to measure the contrast transfer function along the axis of light propagation, relevant for cross-sectional imaging capabilities. (3) Existing and new methods to determine device sensitivity are examined and compared, to better understand the detection limits of OCT. A novel computational model based on the finite-difference time-domain (FDTD) method, which simulates the physics of light behavior at the sub-microscopic level within complex, heterogeneous media, is developed to probe device and tissue characteristics influencing the information content of an OCT image. This model is first tested in simple geometric configurations to understand its accuracy and limitations, then a highly realistic representation of a biological cell, the retinal

  4. Computerized design and generation of space-variant holographic filters. II - Applications of space-variant filters to optical computing

    NASA Technical Reports Server (NTRS)

    Ambs, P.; Fainman, Y.; Esener, S.; Lee, S. H.

    1988-01-01

    Holographic optical elements (HOEs) of space-variant impulse response have been designed and generated using a computerized optical system. HOEs made of dichromated gelatin have been produced and used for spatial light modulator defect removal and optical interconnects. Experimental performance and characteristics are presented.

  5. 200Gb/s 10-channel miniature optical interconnect transmitter module for high-performance computing (HPC)

    NASA Astrophysics Data System (ADS)

    Mohammed, Edris; Au, Hinmeng

    2010-02-01

    A major breakthrough to alleviating the interconnect bottleneck in intra cabinet system in HPC may happen by bringing optics directly to the processor package. In order to do so efficient and compact optical interconnect subassembly modules that utilize simple optical and electrical interfacing schemes are needed. In our current work the development of a novel 10-channel, miniature 7mm(W)x1.8mm(L)x3mm(H), optical interconnect transmitter subassembly module is described. The module consists of a high precision molded optical alignment unit with integrated microlens arrays, highspeed coplanar waveguide (CPW) electrical interfaces and a VCSEL (Vertical Cavity Surface Emitting Laser) array chip which is flip chip mounted. The module is designed to uniquely interface vertically with high-speed electrical I/O lines on a microprocessor style package or a motherboard to convert electrical signals to optical for transmission to other similar units using a standard (Multi-Terminal) MT style optical connector. We report on optical coupling efficiency, misalignment tolerance and high-speed electrical and optical measurements of the module. We have measured 40Gb/s electrical eye for the CPW interfaces on the module and 20Gb/s clear optical eyes for VCSEL assembled module from all the 10 channels to produce an aggregate transmitter bandwidth of 200Gb/s. We also measured 30Gb/s electrical and 20Gb/s optical eyes for the optical subassembly module that is bonded onto a microprocessor style package substrate.

  6. Computation of broad spectral band electro-optical system transmittance response characteristics to military smokes and obscurants using field test data from transmissometer system measurements

    NASA Astrophysics Data System (ADS)

    Farmer, W. Michael; Davis, Roger; Laughman, Robert; Watkins, Wendall

    1990-03-01

    Electro-optical weapon system developers and users must know the smoke/obscurant countermeasure transmittance levels required to defeat their systems. This information is required in order to establish both operational smoke screen requirements and system scenario applicability. Transmittance data acquired in field tests such as the Smoke Week tests, Smoke/Obscurants were developed for this purpose. Narrow-band transmittance data can be analyzed using the Beer-Bouguer transmittance law to evaluate the performance of narrow-band electro-optical weapon systems such as laser rangefinders. However, broadband transmittance data for smokes such as phosphorus, fog oil, and dust in the visible, 3 to 5, or 8 to 12 micron bands cannot be evaluated directly using the Beer-Bouguer transmission law for broadband electro-optical systems such as FLIRs. A method for transforming field-measured transmittance data into equivalent electro-optical system transmittance is required. The transmissometer system analysis developed in the Project Manager, Smoke/Obscurants TRANSmissometer VALidation (TRANSVAL) program has provided the basis for developing such a method. The method developed in the TRANSVAL program for computing equivalent broadband electro-optical sensor transmittance from field test data is described. It is shown that band averages of the mass extinction coefficient used with the Beer-Bouguer transmission law do not yield correct estimates of equivalent electro-optical system transmittance. Examples are provided to illustrate the kinds of errors that can arise if sensor performance is incorrectly interpreted using field test data.

  7. Optic Strut and Para-clinoid Region – Assessment by Multi-detector Computed Tomography with Multiplanar and 3 Dimensional Reconstructions

    PubMed Central

    Ravikiran, S.R.; Kumar, Ashvini; Chavadi, Channabasappa; Pulastya, Sanyal

    2015-01-01

    Purpose To evaluate thickness, location and orientation of optic strut and anterior clinoid process and variations in paraclinoid region, solely based on multidetector computed tomography (MDCT) images with multiplanar (MPR) and 3 dimensional (3D) reconstructions, among Indian population. Materials and Methods Ninety five CT scans of head and paranasal sinuses patients were retrospectively evaluated with MPR and 3D reconstructions to assess optic strut thickness, angle and location, variations like pneumatisation, carotico-clinoid foramen and inter-clinoid osseous ridge. Results Mean optic strut thickness was 3.64mm (±0.64), optic strut angle was 42.67 (±6.16) degrees. Mean width and length of anterior clinoid process were 10.65mm (±0.79) and 11.20mm (±0.95) respectively. Optic strut attachment to sphenoid body was predominantly sulcal as in 52 cases (54.74%) and was most frequently attached to anterior 2/5th of anterior clinoid process, seen in 93 sides (48.95%). Pneumatisation of optic strut occurred in 23 sides. Carotico-clinoid foramen was observed in 42 cases (22.11%), complete foramen in 10 cases (5.26%), incomplete foramen in 24 cases (12.63%) and contact type in 8 cases (4.21%). Inter-clinoid osseous bridge was seen unilaterally in 4 cases. Conclusion The study assesses morphometric features and anatomical variations of paraclinoid region using MDCT 3D and multiplanar reconstructions in Indian population. PMID:26557589

  8. A bio-inspired, computational model suggests velocity gradients of optic flow locally encode ordinal depth at surface borders and globally they encode self-motion.

    PubMed

    Raudies, Florian; Ringbauer, Stefan; Neumann, Heiko

    2013-09-01

    Visual navigation requires the estimation of self-motion as well as the segmentation of objects from the background. We suggest a definition of local velocity gradients to compute types of self-motion, segment objects, and compute local properties of optical flow fields, such as divergence, curl, and shear. Such velocity gradients are computed as velocity differences measured locally tangent and normal to the direction of flow. Then these differences are rotated according to the local direction of flow to achieve independence of that direction. We propose a bio-inspired model for the computation of these velocity gradients for video sequences. Simulation results show that local gradients encode ordinal surface depth, assuming self-motion in a rigid scene or object motions in a nonrigid scene. For translational self-motion velocity, gradients can be used to distinguish between static and moving objects. The information about ordinal surface depth and self-motion can help steering control for visual navigation.

  9. Polymer Gelatin Waveguide In Conjuction With Integrated Holographic Optical Elements On GaAs, LiNb03, Glass, And Aluminum Substrates For Optical Interconnects, Signal Processing, And Computing

    NASA Astrophysics Data System (ADS)

    Chen, Ray T.

    1990-02-01

    We have observed waveguiding in thin films of polymer gelatin on GaAs, LiNb03, glass and aluminum substrates. A graded index profile can be induced in the gelatin layer and tuned by wet processing. This makes it possible to form waveguides on any smooth surface. Locally sensitizing the gelatin waveguide with ammonium dichromate allows us to integrate single and multiplexed gratings on the same substrate to perform various functions for optical interconnects and signal processing. A waveguide grating coupler that converts free space TEM00 laser light to a two dimensional spherical guided wave with 50° angle of divergence has also demonstrated. A passive broadcasting network can be formed using this new technology. Further plausible applications such as WD(D)M local area network, optical interconnection, and optical computing are also presented.

  10. Optics and Symbolic Computing

    DTIC Science & Technology

    1987-03-01

    Tree Representation, and S(c) The Tree Structure Model 216 59 Tree Grammar for a Noise-Free Pattern in Figure 58 217 60 Viewing Geometry for Defining...intensive activity, relying upon knowledge of the grammar and the context to attach meaning to the input sentence or phrase. Knowledge of these and...determine meaning from spoken input. In the introduction to this section, we introduced the concepts of syntax (the sentence structur, and grammar ) and

  11. Optical Computing Research.

    DTIC Science & Technology

    1986-06-30

    the problem of intensity inversion using an inherent nonlinear property of the phase-conjugation process in photorefractives. This work was published...U.S. Air Force Captain at Stanford in a Ph.D. program. This individual has now completed his Ph.D. thesis in the area of optimal imaging concentrators...alloca- tion problem. -6- 2. Matrix inversion and image deblurring problems. 3. Signal processing problems, including spectral analysis. The results of

  12. Optical Computing Strategies

    DTIC Science & Technology

    1990-02-01

    IThe following speed analysis is based on a system of linear equations with ze, n. i 4.1 Digital Processor The total time required, TDT, to solve the...weight, power, time , and cost would be the solv- The generic system is comprised of three properly er (direct or iterative) of the problem solved by...algebraic .*) equations of the discretized system . An analysis simi- Here A is a given matrix, b is a given vector, and x is the lar to the above treatment

  13. A personal-computer-based method to obtain "star-shots" of mechanical and optical isocenters for gantry rotation of linear accelerators.

    PubMed

    Woo, M K

    2002-12-01

    This work describes a method to obtain "star-shots" of the mechanical and optical isocenters of linear accelerators, similar to the star-shots of radiation isocenters normally obtained using films. In this method a digital camera is connected to a personal computer so that multiply exposed images can be taken at a fixed camera position. A mechanical pointer or a wire aligned along the optical axis can then be imaged by the camera. Multiple exposures at varying gantry angles are then superimposed on a digital image which can be analyzed by the computer to give a high-resolution star-shot. The method provides a convenient way for a linear accelerator quality assurance procedure.

  14. An investigation of the potential of optical computed tomography for imaging of synchrotron-generated x-rays at high spatial resolution

    NASA Astrophysics Data System (ADS)

    Doran, Simon J.; Brochard, Thierry; Adamovics, John; Krstajic, Nikola; Bräuer-Krisch, Elke

    2010-03-01

    X-ray microbeam radiation therapy (MRT) is a novel form of treatment, currently in its preclinical stage, which uses microplanar x-ray beams from a synchrotron radiation source. It is important to perform accurate dosimetry on these microbeams, but, to date, there has been no accurate enough method available for making 3D dose measurements with isotropic, high spatial resolution to verify the results of Monte Carlo dose simulations. Here, we investigate the potential of optical computed tomography for satisfying these requirements. The construction of a simple optical CT microscopy (optical projection tomography) system from standard commercially available hardware is described. The measurement of optical densities in projection data is shown to be highly linear (r2 = 0.999). The depth-of-field (DOF) of the imaging system is calculated based on the previous literature and measured experimentally using a commercial DOF target. It is shown that high quality images can be acquired despite the evident lack of telecentricity and despite DOF of the system being much lower than the sample diameter. Possible reasons for this are discussed. Results are presented for a complex irradiation of a 22 mm diameter cylinder of the radiochromic polymer PRESAGE™, demonstrating the exquisite 'dose-painting' abilities available in the MRT hutch of beamline ID-17 at the European Synchrotron Radiation Facility. Dose distributions in this initial experiment are equally well resolved on both an optical CT scan and a corresponding transmission image of radiochromic film, down to a line width of 83 µm (6 lp mm-1) with an MTF value of 0.40. A group of 33 µm wide lines was poorly resolved on both the optical CT and film images, and this is attributed to an incorrect exposure time calculation, leading to under-delivery of dose. Image artefacts in the optical CT scan are discussed. PRESAGE™ irradiated using the microbeam facility is proposed as a suitable material for producing phantom

  15. Stray light in cone beam optical computed tomography: I. Measurement and reduction strategies with planar diffuse source.

    PubMed

    Granton, Patrick V; Dekker, Kurtis H; Battista, Jerry J; Jordan, Kevin J

    2016-04-07

    Optical cone-beam computed tomographic (CBCT) scanning of 3D radiochromic dosimeters may provide a practical method for 3D dose verification in radiation therapy. However, in cone-beam geometry stray light contaminates the projection images, degrading the accuracy of reconstructed linear attenuation coefficients. Stray light was measured using a beam pass aperture array (BPA) and structured illumination methods. The stray-to-primary ray ratio (SPR) along the central axis was found to be 0.24 for a 5% gelatin hydrogel, representative of radiochromic hydrogels. The scanner was modified by moving the spectral filter from the detector to the source, changing the light's spatial fluence pattern and lowering the acceptance angle by extending distance between the source and object. These modifications reduced the SPR significantly from 0.24 to 0.06. The accuracy of the reconstructed linear attenuation coefficients for uniform carbon black liquids was compared to independent spectrometer measurements. Reducing the stray light increased the range of accurate transmission readings. In order to evaluate scanner performance for the more challenging application to small field dosimetry, a carbon black finger gel phantom was prepared. Reconstructions of the phantom from CBCT and fan-beam CT scans were compared. The modified source resulted in improved agreement. Subtraction of residual stray light, measured with BPA or structured illumination from each projection further improved agreement. Structured illumination was superior to BPA for measuring stray light for the smaller 1.2 and 0.5 cm diameter phantom fingers. At the costs of doubling the scanner size and tripling the number of scans, CBCT reconstructions of low-scattering hydrogel dosimeters agreed with those of fan-beam CT scans.

  16. Stray light in cone beam optical computed tomography: I. Measurement and reduction strategies with planar diffuse source

    NASA Astrophysics Data System (ADS)

    Granton, Patrick V.; Dekker, Kurtis H.; Battista, Jerry J.; Jordan, Kevin J.

    2016-04-01

    Optical cone-beam computed tomographic (CBCT) scanning of 3D radiochromic dosimeters may provide a practical method for 3D dose verification in radiation therapy. However, in cone-beam geometry stray light contaminates the projection images, degrading the accuracy of reconstructed linear attenuation coefficients. Stray light was measured using a beam pass aperture array (BPA) and structured illumination methods. The stray-to-primary ray ratio (SPR) along the central axis was found to be 0.24 for a 5% gelatin hydrogel, representative of radiochromic hydrogels. The scanner was modified by moving the spectral filter from the detector to the source, changing the light’s spatial fluence pattern and lowering the acceptance angle by extending distance between the source and object. These modifications reduced the SPR significantly from 0.24 to 0.06. The accuracy of the reconstructed linear attenuation coefficients for uniform carbon black liquids was compared to independent spectrometer measurements. Reducing the stray light increased the range of accurate transmission readings. In order to evaluate scanner performance for the more challenging application to small field dosimetry, a carbon black finger gel phantom was prepared. Reconstructions of the phantom from CBCT and fan-beam CT scans were compared. The modified source resulted in improved agreement. Subtraction of residual stray light, measured with BPA or structured illumination from each projection further improved agreement. Structured illumination was superior to BPA for measuring stray light for the smaller 1.2 and 0.5 cm diameter phantom fingers. At the costs of doubling the scanner size and tripling the number of scans, CBCT reconstructions of low-scattering hydrogel dosimeters agreed with those of fan-beam CT scans.

  17. Covisualization by computational optical-sectioning microscopy of integrin and associated proteins at the cell membrane of living onion protoplasts

    NASA Technical Reports Server (NTRS)

    Gens, J. S.; Reuzeau, C.; Doolittle, K. W.; McNally, J. G.; Pickard, B. G.; Evans, M. L. (Principal Investigator)

    1996-01-01

    Using higher-resolution wide-field computational optical-sectioning fluorescence microscopy, the distribution of antigens recognized by antibodies against animal beta 1 integrin, fibronectin, and vitronectin has been visualized at the outer surface of enzymatically protoplasted onion epidermis cells and in depectinated cell wall fragments. On the protoplast all three antigens are colocalized in an array of small spots, as seen in raw images, in Gaussian filtered images, and in images restored by two different algorithms. Fibronectin and vitronectin but not beta 1 integrin antigenicities colocalize as puncta in comparably prepared and processed images of the wall fragments. Several control visualizations suggest considerable specifity of antibody recognition. Affinity purification of onion cell extract with the same anti-integrin used for visualization has yielded protein that separates in SDS-PAGE into two bands of about 105-110 and 115-125 kDa. These bands are again recognized by the visualization antibody, which was raised against the extracellular domain of chicken beta 1 integrin, and are also recognized by an antibody against the intracellular domain of chicken beta 1 integrin. Because beta 1 integrin is a key protein in numerous animal adhesion sites, it appears that the punctate distribution of this protein in the cell membranes of onion epidermis represents the adhesion sites long known to occur in cells of this tissue. Because vitronectin and fibronection are matrix proteins that bind to integrin in animals, the punctate occurrence of antigenically similar proteins both in the wall (matrix) and on enzymatically prepared protoplasts reinforces the concept that onion cells have adhesion sites with some similarity to certain kinds of adhesion sites in animals.

  18. Evaluation of the aero-optical properties of the SOFIA cavity by means of computional fluid dynamics and a super fast diagnostic camera

    NASA Astrophysics Data System (ADS)

    Engfer, Christian; Pfüller, Enrico; Wiedemann, Manuel; Wolf, Jürgen; Lutz, Thorsten; Krämer, Ewald; Röser, Hans-Peter

    2012-09-01

    The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a 2.5 m reflecting telescope housed in an open cavity on board of a Boeing 747SP. During observations, the cavity is exposed to transonic flow conditions. The oncoming boundary layer evolves into a free shear layer being responsible for optical aberrations and for aerodynamic and aeroacoustic disturbances within the cavity. While the aero-acoustical excitation of an airborne telescope can be minimized by using passive flow control devices, the aero-optical properties of the flow are difficult to improve. Hence it is important to know how much the image seen through the SOFIA telescope is perturbed by so called seeing effects. Prior to the SOFIA science fights Computational Fluid Dynamics (CFD) simulations using URANS and DES methods were carried out to determine the flow field within and above the cavity and hence in the optical path in order to provide an assessment of the aero-optical properties under baseline conditions. In addition and for validation purposes, out of focus images have been taken during flight with a Super Fast Diagnostic Camera (SFDC). Depending on the binning factor and the sub-array size, the SFDC is able to take and to read out images at very high frame rates. The paper explains the numerical approach based on CFD to evaluate the aero-optical properties of SOFIA. The CFD data is then compared to the high speed images taken by the SFDC during flight.

  19. Atomistic tight-binding computations in structural and optical properties of CdSe/ZnSe/ZnS core/multi-shell nanocrystals

    NASA Astrophysics Data System (ADS)

    Sukkabot, Worasak

    2016-07-01

    In the present paper, I attempt to theoretically describe, analyze and compare the structural and optical properties in the core/multi-shell nanocrystal structure of a cadmium selenide (CdSe) core surrounded by zinc selenide (ZnSe) inner and zinc sulphide (ZnS) external growth shells. The atomistic tight-binding model (TB) and a configuration interaction method (CI) are implemented to calculate the single-particle spectra, optical band gaps, ground-state wave function overlaps, ground-state oscillation strengths, ground-state coulomb energies, ground-state exchange energies and Stokes shift as a function of ZnS external growth shell thicknesses. I underline that these computations are principally sensitive with the ZnS external growth shell thickness. The reduction of the optical band gaps, overlaps of ground electron-hole wave function, electron-hole interactions and Stokes shift is realized with the increasing ZnS external growth shell thickness. The improvement of the optical intensities is mainly achieved by including the ZnS exterior growth shell encapsulation. Importantly, the optical band gaps based on atomistic tight-binding theory are in a good agreement with the experiment. Finally, this emphasizes that the external passivation shell can now be engineered in a defined way, thus leading to manipulate the natural behaviors of nanodevices based on the scrutinized core/multi-shell nanocrystals.

  20. Characterizing energy dependence and count rate performance of a dual scintillator fiber-optic detector for computed tomography

    SciTech Connect

    Hoerner, Matthew R. Stepusin, Elliott J.; Hyer, Daniel E.; Hintenlang, David E.

    2015-03-15

    Purpose: Kilovoltage (kV) x-rays pose a significant challenge for radiation dosimetry. In the kV energy range, even small differences in material composition can result in significant variations in the absorbed energy between soft tissue and the detector. In addition, the use of electronic systems in light detection has demonstrated measurement losses at high photon fluence rates incident to the detector. This study investigated the feasibility of using a novel dual scintillator detector and whether its response to changes in beam energy from scatter and hardening is readily quantified. The detector incorporates a tissue-equivalent plastic scintillator and a gadolinium oxysulfide scintillator, which has a higher sensitivity to scatter x-rays. Methods: The detector was constructed by coupling two scintillators: (1) small cylindrical plastic scintillator, 500 μm in diameter and 2 mm in length, and (2) 100 micron sheet of gadolinium oxysulfide 500 μm in diameter, each to a 2 m long optical fiber, which acts as a light guide to transmit scintillation photons from the sensitive element to a photomultiplier tube. Count rate linearity data were obtained from a wide range of exposure rates delivered from a radiological x-ray tube by adjusting the tube current. The data were fitted to a nonparalyzable dead time model to characterize the time response. The true counting rate was related to the reference free air dose air rate measured with a 0.6 cm{sup 3} Radcal{sup ®} thimble chamber as described in AAPM Report No. 111. Secondary electron and photon spectra were evaluated using Monte Carlo techniques to analyze ionization quenching and photon energy-absorption characteristics from free-in-air and in phantom measurements. The depth/energy dependence of the detector was characterized using a computed tomography dose index QA phantom consisting of nested adult head and body segments. The phantom provided up to 32 cm of acrylic with a compatible 0.6 cm{sup 3} calibrated

  1. Implementation of a computationally efficient least-squares algorithm for highly under-determined three-dimensional diffuse optical tomography problems

    PubMed Central

    Yalavarthy, Phaneendra K.; Lynch, Daniel R.; Pogue, Brian W.; Dehghani, Hamid; Paulsen, Keith D.

    2008-01-01

    Three-dimensional (3D) diffuse optical tomography is known to be a nonlinear, ill-posed and sometimes under-determined problem, where regularization is added to the minimization to allow convergence to a unique solution. In this work, a generalized least-squares (GLS) minimization method was implemented, which employs weight matrices for both data-model misfit and optical properties to include their variances and covariances, using a computationally efficient scheme. This allows inversion of a matrix that is of a dimension dictated by the number of measurements, instead of by the number of imaging parameters. This increases the computation speed up to four times per iteration in most of the under-determined 3D imaging problems. An analytic derivation, using the Sherman–Morrison–Woodbury identity, is shown for this efficient alternative form and it is proven to be equivalent, not only analytically, but also numerically. Equivalent alternative forms for other minimization methods, like Levenberg–Marquardt (LM) and Tikhonov, are also derived. Three-dimensional reconstruction results indicate that the poor recovery of quantitatively accurate values in 3D optical images can also be a characteristic of the reconstruction algorithm, along with the target size. Interestingly, usage of GLS reconstruction methods reduces error in the periphery of the image, as expected, and improves by 20% the ability to quantify local interior regions in terms of the recovered optical contrast, as compared to LM methods. Characterization of detector photomultiplier tubes noise has enabled the use of the GLS method for reconstructing experimental data and showed a promise for better quantification of target in 3D optical imaging. Use of these new alternative forms becomes effective when the ratio of the number of imaging property parameters exceeds the number of measurements by a factor greater than 2. PMID:18561643

  2. Experimental Investigation and Computer Modeling of Optical Switching in Distributed Bragg Reflector and Vertical Cavity Surface Emitting Laser Structures.

    DTIC Science & Technology

    1995-12-01

    Panish. Heterostructure Lasers, Part A: Fundamental Principles. Quantum Electronics : Principles and Applications, Orlando: Academic Press, Inc., 1978...John Wiley & Sons, 1978. 15. Gibbs, H.M. Optical Bistability: Controlling Light with Light. Quantum Electronics - Principles and Applications, Orlando

  3. Organization of the Topical Meeting on Optical Computing Held in Toulon, France on 29 August-2 September 1988

    DTIC Science & Technology

    1988-09-02

    constructing optical multilayer networks, such as back propagation machines or pipe-line optical processors. The authors would like to thank Drs...add to produce N spots. This incoherent addition is performed by means of a difusor on the write side of the LCLV. The intensity of the spots give the...Isolation may be achieved by the A major diffilty with data stoage using holograms refractive index differences, coatings on the sides , or the recorded in

  4. The influence of glass fibers on elongational viscosity studied by means of optical coherence tomography and X-ray computed tomography

    SciTech Connect

    Aigner, M. Köpplmayr, T. E-mail: Christian.lang@jku.at; Lang, C. E-mail: Christian.lang@jku.at; Burzic, I. E-mail: juergen.miethlinger@jku.at; Miethlinger, J. E-mail: juergen.miethlinger@jku.at; Salaberger, D.; Buchsbaum, A. Leitner, M.; Heise, B.; Schausberger, S. E. Stifter, D.

    2014-05-15

    We report on the flow characteristics of glass-fiber-reinforced polymers in elongational rheometry. Unlike polymers with geometrically isotropic fillers, glass-fiber-reinforced polymers exhibit flow behavior and rheology that depend heavily on the orientation, the length distribution and the content of the fibers. One of the primary objectives of this study was to determine the effect of fiber orientation, concentration and distribution on the entrance pressure drop by means of optical coherence tomography (OCT), full-field optical coherence microscopy (FF-OCM), and X-ray computed tomography (X-CT). Both pressure drop and melt flow were analyzed using a special elongation die (Thermo Scientific X-Die [3]) for inline measurements. Samples with a variety of fiber volume fractions, fiber lengths and processing temperatures were measured.

  5. User's manual for DELSOL2: a computer code for calculating the optical performance and optimal system design for solar-thermal central-receiver plants

    SciTech Connect

    Dellin, T.A.; Fish, M.J.; Yang, C.L.

    1981-08-01

    DELSOL2 is a revised and substantially extended version of the DELSOL computer program for calculating collector field performance and layout, and optimal system design for solar thermal central receiver plants. The code consists of a detailed model of the optical performance, a simpler model of the non-optical performance, an algorithm for field layout, and a searching algorithm to find the best system design. The latter two features are coupled to a cost model of central receiver components and an economic model for calculating energy costs. The code can handle flat, focused and/or canted heliostats, and external cylindrical, multi-aperture cavity, and flat plate receivers. The program optimizes the tower height, receiver size, field layout, heliostat spacings, and tower position at user specified power levels subject to flux limits on the receiver and land constraints for field layout. The advantages of speed and accuracy characteristic of Version I are maintained in DELSOL2.

  6. Computer simulations of effects of disk tilt and lens tilt on push-pull tracking error signal in an optical disk drive.

    PubMed

    Bartlett, C L; Kay, D; Mansuripur, M

    1997-11-10

    We quantify the effects of disk tilt and objective lens tilt on the push-pull tracking error signal of an optical disk data storage system. For a grooved disk, such as a recordable compact disk that operates at a laser wavelength of lambda, it is found that disk tilt produces a tracking offset of 0.05lambda per degree of tilt, whereas objective lens tilt produces an offset of 0.012lambda per degree of tilt. The amplitude of the tracking error signal decreases by 2.5% at the disk tilt angle of 0.3 degrees and by 5% at the objective lens tilt of 0.3 degrees . We achieved these simulations with the computer program Diffract, which performs a combination of diffraction and ray-tracing calculations through the entire optical path, from the light source to the detectors.

  7. Light multinary computing

    NASA Astrophysics Data System (ADS)

    Arago, Jaime

    2012-11-01

    Next-generation optical communication and optical computing imply an evolution from binary to multinary computing. Light multinary computing encodes data using pulses of light components in higher orders than binary and processes it using truth tables larger than Boolean ones. This results in lesser encoded data that can be processed at faster speeds. We use a general-purpose optical transistor as the building block to develop the main computing units for counting, distributing, storing, and logically operating the arithmetic addition of two bytes of base-10 data. Currently available optical switching technologies can be used to physically implement light multinary computing to achieve ultra-high speed communication and computing.

  8. Evaluation and study of advanced optical contamination, deposition, measurement, and removal techniques. [including computer programs and ultraviolet reflection analysis

    NASA Technical Reports Server (NTRS)

    Linford, R. M. F.; Allen, T. H.; Dillow, C. F.

    1975-01-01

    A program is described to design, fabricate and install an experimental work chamber assembly (WCA) to provide a wide range of experimental capability. The WCA incorporates several techniques for studying the kinetics of contaminant films and their effect on optical surfaces. It incorporates the capability for depositing both optical and contaminant films on temperature-controlled samples, and for in-situ measurements of the vacuum ultraviolet reflectance. Ellipsometer optics are mounted on the chamber for film thickness determinations, and other features include access ports for radiation sources and instrumentation. Several supporting studies were conducted to define specific chamber requirements, to determine the sensitivity of the measurement techniques to be incorporated in the chamber, and to establish procedures for handling samples prior to their installation in the chamber. A bibliography and literature survey of contamination-related articles is included.

  9. International Conference on Optical Computing Held in Edinburgh, Scotland on August 22-25, 1994. Technical Digest

    DTIC Science & Technology

    1994-08-24

    34Holographic implementation of a learning machine based on a multicategory perceptron algorithm", Optics Lenrs , J4, no.23, (1989), p. 1303-1305...plane Lenrs Focal plane array of Wen4.ts Of lenm and lens Fig.3 Component layout of interlaced fan-out. Results and discussion The focal plane of the

  10. High security and robust optical image encryption approach based on computer-generated integral imaging pickup and iterative back-projection techniques

    NASA Astrophysics Data System (ADS)

    Li, Xiao Wei; Cho, Sung Jin; Kim, Seok Tae

    2014-04-01

    In this paper, a novel optical image encryption algorithm by combining the use of computer-generated integral imaging (CGII) pickup technique and iterative back-projection (IBP) technique is proposed. In this scheme, a color image to be encrypted which is firstly segregated into three channels: red, green, and blue. Each of these three channels is independently captured by using a virtual pinhole array and be computationally transformed as a sub-image array. Then, each of these three sub-image arrays are scrambled by the Fibonacci transformation (FT) algorithm, respectively. These three scrambled sub-image arrays are encrypted by the hybrid cellular automata (HCA), respectively. Ultimately, these three encrypted images are combined to produce the colored encrypted image. In the reconstruction process, because the computational integral imaging reconstruction (CIIR) is a pixel-overlapping reconstruction technique, the interference of the adjacent pixels will decrease the quality of the reconstructed image. To address this problem, we introduce an image super-resolution reconstruction technique, the image can be computationally reconstructed by the IBP technique. Some numerical simulations are made to test the validity and the capability of the proposed image encryption algorithm.

  11. Computation of the Fluid and Optical Fields About the Stratospheric Observatory for Infrared Astronomy (SOFIA) and the Coupling of Fluids, Dynamics, and Control Laws on Parallel Computers

    NASA Technical Reports Server (NTRS)

    Atwood, Christopher A.

    1993-01-01

    The June 1992 to May 1993 grant NCC-2-677 provided for the continued demonstration of Computational Fluid Dynamics (CFD) as applied to the Stratospheric Observatory for Infrared Astronomy (SOFIA). While earlier grant years allowed validation of CFD through comparison against experiments, this year a new design proposal was evaluated. The new configuration would place the cavity aft of the wing, as opposed to the earlier baseline which was located immediately aft of the cockpit. This aft cavity placement allows for simplified structural and aircraft modification requirements, thus lowering the program cost of this national astronomy resource. Three appendices concerning this subject are presented.

  12. Trifunctional Polymeric Nanocomposites Incorporated with Fe₃O₄/Iodine-Containing Rare Earth Complex for Computed X-ray Tomography, Magnetic Resonance, and Optical Imaging.

    PubMed

    Wang, Xin; Tu, Mengqi; Yan, Kai; Li, Penghui; Pang, Long; Gong, Ying; Li, Qing; Liu, Ruiqing; Xu, Zushun; Xu, Haibo; Chu, Paul K

    2015-11-11

    In this study, a novel polymerizable CT contrast agent integrating iodine with europium(III) has been developed by a facile and universal coordination chemistry method. The Fe3O4 nanoparticles are then incorporated into this iodine-containing europium complex by seed-emulsifier-free polymerization. The nanocomposites combining the difunctional complex and superparamagnetic Fe3O4 nanoparticles, which have uniform size dispersion and high encapsulation rate, are suitable for computed X-ray tomography (CT), magnetic resonance imaging (MRI), and optical imaging. They possess good paramagnetic properties with a maximum saturation magnetization of 2.16 emu/g and a transverse relaxivity rate of 260 mM(-1) s(-1), and they exhibit obvious contrast effects with an iodine payload less than 4.8 mg I/mL. In the in vivo optical imaging assessment, vivid fluorescent dots can be observed in the liver and spleen by two-photon confocal scanning laser microscopy (CLSM). All the results showed that nanocomposites as polymeric trifunctional contrast agents have great clinical potential in CT, MR, and optical imaging.

  13. Transfer and computation of optical topological charges via light pulse buffer memory in an electromagnetically-induced-transparency solid

    NASA Astrophysics Data System (ADS)

    Zhai, Zhaohui; Li, Zhixiang; Xu, Jingjun; Zhang, Guoquan

    2013-09-01

    We verified that optical topological charges are conserved in a two-step light-pulse storage and retrieval process based on the electromagnetically-induced-transparency (EIT) effect in a Pr3+:Y2SiO5 crystal. Based on this conservation law, one could transfer topological charges from the interacting beams, which may not be overlapped in space and time domains, to the targeted output signal beam, and algebraic operations such as summation and subtraction of topological charges carried by the interacting beams were demonstrated via the EIT-assisted two-step light-pulse storage-retrieval process. The results may be useful for classical and quantum information processing based on optical topological charge buffer memory in EIT media.

  14. Computational modeling of the size effects on the optical vibrational modes of H-terminated Ge nanostructures.

    PubMed

    Trejo, Alejandro; Cruz-Irisson, Miguel

    2013-04-22

    The vibrational dispersion relations of porous germanium (pGe) and germanium nanowires (GeNWs) were calculated using the ab initio density functional perturbation theory with a generalized gradient approximation with norm-conserving pseudopotentials. Both pores and nanowires were modeled using the supercell technique. All of the surface dangling bonds were saturated with hydrogen atoms. To address the difference in the confinement between the pores and the nanowires, we calculated the vibrational density of states of the two materials. The results indicate that there is a slight shift in the highest optical mode of the Ge-Ge vibration interval in all of the nanostructures due to the phonon confinement effects. The GeNWs exhibit a reduced phonon confinement compared with the porous Ge due to the mixed Ge-dihydride vibrational modes around the maximum bulk Ge optical mode of approximately 300 cm⁻¹; however, the general effects of such confinements could still be noticed, such as the shift to lower frequencies of the highest optical mode belonging to the Ge vibrations.

  15. Neutron detection and characterization for non-proliferation applications using 3D computer optical memories [Use of 3D optical computer memory for radiation detectors/dosimeters. Final progress report

    SciTech Connect

    Gary W. Phillips

    2000-12-20

    We have investigated 3-dimensional optical random access memory (3D-ORAM) materials for detection and characterization of charged particles of neutrons by detecting tracks left by the recoil charged particles produced by the neutrons. We have characterized the response of these materials to protons, alpha particles and carbon-12 nuclei as a functions of dose and energy. We have observed individual tracks using scanning electron microscopy and atomic force microscopy. We are investigating the use of neural net analysis to characterize energetic neutron fields from their track structure in these materials.

  16. Parametric Investigation of Radome Analysis Methods. Volume II. Computer-Aided Radome Analysis Using Geometrical Optics and Lorentz Reciprocity.

    DTIC Science & Technology

    1981-02-01

    1977-31 Dnc. 1ciR) GEOMETRICAL OPTICS AND LORENTZ RECIPROCITY S. PERFORMING O1G. REPORT NUMBER 7. AUTHOR(s) S. CONTRACT OR GRANT NUMBER(s) G. K...Huddleston, H. L. Bassett, & J. M. Newton kFOSR-77-3469 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK Georgia Institute...and H. L. Bassett, "Multi-Purpose Missile (MPM) High Performance Radome Trade-Off and Development Study", Martin Marietta Aerospace, April 1975. 4. G

  17. Simulation and Optimization of Synchrotron Infrared Micro-Spectroscopic Beamlines using Wave Optics Computation: ESRF and SOLEIL's Cases

    SciTech Connect

    Chubar, O.; Polack, F.; Lagarde, B.; Dumas, P.; Susini, J.; Cotte, M.; Scheidt, K.; Elleaume, P.

    2007-01-19

    Applications of the 'Synchrotron Radiation Workshop' (SRW) computer code to the design and optimization of the mid-infrared micro-spectroscopic beamlines at the ESRF and SOLEIL storage ring are described. The agreement found between SRW simulation, at various positions from the source to the spectrometer, ray tracing calculations and intensity profile measurements demonstrates that SRW is readily an excellent approach to optimize any synchrotron infrared beamline.

  18. Nonlinear Optical Acrylic Polymers and Use Thereof in Optical and Electro-Optic Devices

    DTIC Science & Technology

    1992-01-07

    COVERED 4. TITLE AND SUBTITLE Nonlinear Optical Acrylic Polymers and Use Thereof in Optical and Electro - Optic Devices 5a. CONTRACT NUMBER 5b. GRANT...generators, computational devices and the like. 15. SUBJECT TERMS optical devices, electro - optical devices, optical signal processing...THEREOF IN OPTICAL AND ELECTRO - OPTIC DEVICES [75] Inventors: Le*lie H. Sperling, Bethlehem; Clarence J. Murphy, Stroudsburg; Warren A. Rosen

  19. Optical Firmware

    NASA Technical Reports Server (NTRS)

    Bergman, Larry A.

    1989-01-01

    Data-processing system exploits high speeds inherent in optical elements. Instruction sets for different computer operations reside on different external memory chips. Laser diodes activated for each operation generate light, reflected by holographic optical element to designated receptors in arithmetic and logic unit. Pattern of light beams embodies instruction set at given instant. With potential ability to reprogram in real time, conceptual system applicable to task-driven programming or artificial intelligence.

  20. Integration of 3D anatomical data obtained by CT imaging and 3D optical scanning for computer aided implant surgery

    PubMed Central

    2011-01-01

    Background A precise placement of dental implants is a crucial step to optimize both prosthetic aspects and functional constraints. In this context, the use of virtual guiding systems has been recognized as a fundamental tool to control the ideal implant position. In particular, complex periodontal surgeries can be performed using preoperative planning based on CT data. The critical point of the procedure relies on the lack of accuracy in transferring CT planning information to surgical field through custom-made stereo-lithographic surgical guides. Methods In this work, a novel methodology is proposed for monitoring loss of accuracy in transferring CT dental information into periodontal surgical field. The methodology is based on integrating 3D data of anatomical (impression and cast) and preoperative (radiographic template) models, obtained by both CT and optical scanning processes. Results A clinical case, relative to a fully edentulous jaw patient, has been used as test case to assess the accuracy of the various steps concurring in manufacturing surgical guides. In particular, a surgical guide has been designed to place implants in the bone structure of the patient. The analysis of the results has allowed the clinician to monitor all the errors, which have been occurring step by step manufacturing the physical templates. Conclusions The use of an optical scanner, which has a higher resolution and accuracy than CT scanning, has demonstrated to be a valid support to control the precision of the various physical models adopted and to point out possible error sources. A case study regarding a fully edentulous patient has confirmed the feasibility of the proposed methodology. PMID:21338504

  1. Numerical Computation of Optical Properties of Internally Mixed Soot in Biomass Burning Constrained by Field and Laboratory Observations

    NASA Astrophysics Data System (ADS)

    China, S.; Scarnato, B. V.; Gorkowski, K.; Aiken, A. C.; Liu, S.; Dubey, M. K.; Mazzoleni, C.

    2014-12-01

    Carbonaceous aerosol emitted from biomass burning (BB) contributes significantly to atmospheric aerosol loadings regionally and globally. Direct radiative forcing of BB aerosol is highly uncertain due to its complex composition, morphology and mixing state. Soot particles are the strongest light absorbing aerosols in BB smoke. In BB smoke, soot particles are normally internally mixed with other material and the mixing state can affect their optical properties. In this study we investigated morphology and mixing state of soot particles emitted from BB smoke from field and laboratory measurements. Smoke particles were collected 1) during the Las Conchas wildfire in New Mexico (June, 2011) and 2) at the U.S. Forest Service's Fire Science Laboratory in 2012, during the fourth Fire Laboratory at Missoula Experiment (FLAME-4). Single particles were analyzed with electron microscopy, and were categorized and characterized by their morphology, and mixing state. We found that soot particles were mostly heavily coated. Based on the characterization on field and laboratory samples, synthetic soot particles with various morphologies and mixing states were generated and their optical properties were numerically calculated using the discrete dipole approximation. We used organic material as a coating agent and investigated the spectral dependency of scattering and absorption for internally mixed soot particles. We found enhancement in scattering and absorption when most of the soot particle was embedded within the organic coating. The aim of this study is to improve our understanding of the effect of morphology and mixing on light scattering and absorption by soot particles and ultimately their effects on the direct radiative forcing.

  2. Computer modeling of the optical properties and heating of spherical gold and silica-gold nanoparticles for laser combined imaging and photothermal treatment.

    PubMed

    Pustovalov, V; Astafyeva, L; Jean, B

    2009-06-03

    Recently, several groups of investigators (Anderson, Halas, Zharov, El-Sayed and their co-workers (Pitsillides et al 2003 Biophys. J. 84 4023-31, Zharov et al 2003 Appl. Phys. Lett. 83 4897-9, Zharov et al 2004 Proc. SPIE 5319 291-9, Loo et al 2005 Nano Lett. 5 709-11, Gobin et al 2007 Nano Lett. 7 1929-34, Fu et al 2008 Nanotechnology 19 045103, Huang et al 2006 J. Am. Chem. Soc. 128 2115-20, Jain et al 2006 J. Phys. Chem. B 110 7238-48, Jain et al 2007 Nano Today 2 18-29)) demonstrated, through pioneering results, the great potential of laser thermal therapy of cells and tissues conjugated with gold nanoparticles. It was also proposed to use combined diagnostics and therapy on the basis of nanoparticle selection for achievement of efficient contrast for laser imaging applications, as well as for photothermal therapy. However, the current understanding of the relationship between optical properties (absorption, backscattering) of nanoparticles, the efficiency of nanoparticle heating and the possibility to use them for combined imaging and therapy is limited. Here, we report the results of computer modeling of optical absorption and backscattering properties and laser heating of gold and silica-gold spherical nanoparticles for laser combined imaging and photothermal treatment of cells and tissues conjugated with nanoparticles. The efficiencies of nanoparticle heating and backscattering by nanoparticles, depending upon their radii, structure and optical properties of the metal, were investigated. This paper focuses on the analysis and determination of appropriate ranges of nanoparticle sizes for the purposes of laser combined imaging and photothermal treatment. The possibility to use spherical gold and silica-gold nanoparticles in determined ranges of radii for these purposes for laser wavelengths 532 and 800 nm is investigated.

  3. Performance evaluation of an improved optical computed tomography polymer gel dosimeter system for 3D dose verification of static and dynamic phantom deliveries

    SciTech Connect

    Lopatiuk-Tirpak, O.; Langen, K. M.; Meeks, S. L.; Kupelian, P. A.; Zeidan, O. A.; Maryanski, M. J.

    2008-09-15

    The performance of a next-generation optical computed tomography scanner (OCTOPUS-5X) is characterized in the context of three-dimensional gel dosimetry. Large-volume (2.2 L), muscle-equivalent, radiation-sensitive polymer gel dosimeters (BANG-3) were used. Improvements in scanner design leading to shorter acquisition times are discussed. The spatial resolution, detectable absorbance range, and reproducibility are assessed. An efficient method for calibrating gel dosimeters using the depth-dose relationship is applied, with photon- and electron-based deliveries yielding equivalent results. A procedure involving a preirradiation scan was used to reduce the edge artifacts in reconstructed images, thereby increasing the useful cross-sectional area of the dosimeter by nearly a factor of 2. Dose distributions derived from optical density measurements using the calibration coefficient show good agreement with the treatment planning system simulations and radiographic film measurements. The feasibility of use for motion (four-dimensional) dosimetry is demonstrated on an example comparing dose distributions from static and dynamic delivery of a single-field photon plan. The capability to visualize three-dimensional dose distributions is also illustrated.

  4. Performance evaluation of an improved optical computed tomography polymer gel dosimeter system for 3D dose verification of static and dynamic phantom deliveries.

    PubMed

    Lopatiuk-Tirpak, O; Langen, K M; Meeks, S L; Kupelian, P A; Zeidan, O A; Maryanski, M J

    2008-09-01

    The performance of a next-generation optical computed tomography scanner (OCTOPUS-5X) is characterized in the context of three-dimensional gel dosimetry. Large-volume (2.2 L), muscle-equivalent, radiation-sensitive polymer gel dosimeters (BANG-3) were used. Improvements in scanner design leading to shorter acquisition times are discussed. The spatial resolution, detectable absorbance range, and reproducibility are assessed. An efficient method for calibrating gel dosimeters using the depth-dose relationship is applied, with photon- and electron-based deliveries yielding equivalent results. A procedure involving a preirradiation scan was used to reduce the edge artifacts in reconstructed images, thereby increasing the useful cross-sectional area of the dosimeter by nearly a factor of 2. Dose distributions derived from optical density measurements using the calibration coefficient show good agreement with the treatment planning system simulations and radiographic film measurements. The feasibility of use for motion (four-dimensional) dosimetry is demonstrated on an example comparing dose distributions from static and dynamic delivery of a single-field photon plan. The capability to visualize three-dimensional dose distributions is also illustrated.

  5. A closer look at the physical and optical properties of gold nanostars: an experimental and computational study.

    PubMed

    Tsoulos, T V; Han, L; Weir, J; Xin, H L; Fabris, L

    2017-03-17

    A combined experimental and computational study was carried out to design a semi-empirical method to determine the volume, surface area, and extinction coefficients of gold nanostars. The values obtained were confirmed by reconstructing the nanostar 3D topography through high-tilt TEM tomography and introducing the finite elements in COMSOL Multiphysics through which we have also calculated the morphology-dependent extinction coefficient. Doing so, we have, for the first time, modeled the heat losses of a real, experimentally synthesized nanostar, and found the plasmon resonances to be in excellent agreement with those obtained experimentally. We believe that our approach could substantially improve the applicability of this remarkable nanomaterial.

  6. Considerations in video playback design: using optic flow analysis to examine motion characteristics of live and computer-generated animation sequences.

    PubMed

    Woo, Kevin L; Rieucau, Guillaume

    2008-07-01

    The increasing use of the video playback technique in behavioural ecology reveals a growing need to ensure better control of the visual stimuli that focal animals experience. Technological advances now allow researchers to develop computer-generated animations instead of using video sequences of live-acting demonstrators. However, care must be taken to match the motion characteristics (speed and velocity) of the animation to the original video source. Here, we presented a tool based on the use of an optic flow analysis program to measure the resemblance of motion characteristics of computer-generated animations compared to videos of live-acting animals. We examined three distinct displays (tail-flick (TF), push-up body rock (PUBR), and slow arm wave (SAW)) exhibited by animations of Jacky dragons (Amphibolurus muricatus) that were compared to the original video sequences of live lizards. We found no significant differences between the motion characteristics of videos and animations across all three displays. Our results showed that our animations are similar the speed and velocity features of each display. Researchers need to ensure that similar motion characteristics in animation and video stimuli are represented, and this feature is a critical component in the future success of the video playback technique.

  7. Concept for Inclusion of Analytical and Computational Capability in Optical Plume Anomaly Detection (OPAD) for Measurement of Neutron Flux

    NASA Technical Reports Server (NTRS)

    Patrick, M. Clinton; Cooper, Anita E.; Powers, W. T.

    2004-01-01

    Researchers are working on many konts to make possible high speed, automated classification and quantification of constituent materials in numerous environments. NASA's Marshall Space Flight Center has implemented a system for rocket engine flow fields/plumes; the Optical Plume Anomaly Detection (OPAD) system was designed to utilize emission and absorption spectroscopy for monitoring molecular and atomic particulates in gas plasma. An accompanying suite of tools and analytical package designed to utilize information collected by OPAD is known as the Engine Diagnostic Filtering System (EDIFIS). The current combination of these systems identifies atomic and molecular species and quantifies mass loss rates in H2/O2 rocket plumes. Additionally, efforts are being advanced to hardware encode components of the EDIFIS in order to address real-time operational requirements for health monitoring and management. This paper addresses the OPAD with its tool suite, and discusses what is considered a natural progression: a concept for migrating OPAD towards detection of high energy particles, including neutrons and gamma rays. The integration of these tools and capabilities will provide NASA with a systematic approach to monitor space vehicle internal and external environment.

  8. Computational study: how redox affect the nonlinear optical properties of donor substituted heteroleptic bis-tridentate Ru(II) complexes?

    PubMed

    Sun, Xiu-Xin; Ma, Na-Na; Li, Xiao-Juan; Sun, Shi-Ling; Xie, Hai-Ming; Qiu, Yong-Qing

    2012-09-01

    Donor substituted heteroleptic bis-tridentate Ru(II) complexes with different deprotonated forms exhibit larger alterations of the first hyperpolarizabilities in oxidized process and are promising to become redox-switchable nonlinear optical (NLO) molecular materials. For systems with diprotonated form, the β(vec) value of the two-electron-oxidized system ¹3²⁺ is 5.3 and 178.6 times as large as those of the reduced parent 3 and the one-electron-oxidized system 3⁺ according to the DFT-FF results. For systems with mono-protonated form, the oxidization of the deprotonated benzimidazole anion is more helpful to enhance the β(vec) value because of the increasing β(x) component. For systems with fully deprotonated form, the largest ratio of |β(vec)((1″)⁺)/β(vec)(1″)| of the system without substituent is about 13.2 due to the dominant off-diagonal tensor β(zxx). And the time-dependent density functional theory (TDDFT) results indicate that the charge transfer transition of the first excited state displays an indispensable role for larger off-diagonal tensor. Finally, the calculated frequency-dependent β results exhibit a small dispersion effect at the low-frequency region.

  9. Accurately computing the optical pathlength difference for a michelson interferometer with minimal knowledge of the source spectrum.

    PubMed

    Milman, Mark H

    2005-12-01

    Astrometric measurements using stellar interferometry rely on precise measurement of the central white light fringe to accurately obtain the optical pathlength difference of incoming starlight to the two arms of the interferometer. One standard approach to stellar interferometry uses a channeled spectrum to determine phases at a number of different wavelengths that are then converted to the pathlength delay. When throughput is low these channels are broadened to improve the signal-to-noise ratio. Ultimately the ability to use monochromatic models and algorithms in each of the channels to extract phase becomes problematic and knowledge of the spectrum must be incorporated to achieve the accuracies required of the astrometric measurements. To accomplish this an optimization problem is posed to estimate simultaneously the pathlength delay and spectrum of the source. Moreover, the nature of the parameterization of the spectrum that is introduced circumvents the need to solve directly for these parameters so that the optimization problem reduces to a scalar problem in just the pathlength delay variable. A number of examples are given to show the robustness of the approach.

  10. Concept for Inclusion of Analytical and Computational Capability in Optical Plume Anomaly Detection (OPAD) for Measurement of Neutron Flux

    NASA Technical Reports Server (NTRS)

    Patrick, Marshall Clint; Cooper, Anita E.; Powers, W. T.

    2004-01-01

    Researchers are working on many fronts to make possible high-speed, automated classification and quantification of constituent materials in numerous environments. NASA's Marshall Space Flight Center has implemented a system for rocket engine flowfields/plumes. The Optical Plume Anomaly Detector (OPAD) system was designed to utilize emission and absorption spectroscopy for monitoring molecular and atomic particulates in gas plasma. An accompanying suite of tools and analytical package designed to utilize information collected by OPAD is known as the Engine Diagnostic Filtering System (EDiFiS). The current combination of these systems identifies atomic and molecular species and quantifies mass loss rates in H2/O2 rocket plumes. Capabilities for real-time processing are being advanced on several fronts, including an effort to hardware encode components of the EDiFiS for health monitoring and management. This paper addresses the OPAD with its tool suites, and discusses what is considered a natural progression: a concept for taking OPAD to the next logical level of high energy physics, incorporating fermion and boson particle analyses in measurement of neutron flux.

  11. A closer look at the physical and optical properties of gold nanostars: an experimental and computational study

    DOE PAGES

    Tsoulos, T. V.; Han, L.; Weir, J.; ...

    2017-02-22

    A combined experimental and computational study was carried out to design a semi-empirical method to determine the volume, surface area, and extinction coefficients of gold nanostars. The values obtained were confirmed by reconstructing the nanostar 3D topography through high-tilt TEM tomography and introducing the finite elements in COMSOL Multiphysics through which we have also calculated the morphology-dependent extinction coefficient. We have, for the first time, modeled the heat losses of a real, experimentally synthesized nanostar, and found the plasmon resonances to be in excellent agreement with those obtained experimentally. Furthermore, we believe that our approach could substantially improve the applicabilitymore » of this remarkable nanomaterial.« less

  12. Fluorescent Styryl Dyes from 4-Chloro-2-(Diphenylamino)-1, 3-Thiazole-5-Carbaldehyde-Synthesis, Optical Properties and TDDFT Computations.

    PubMed

    Sekar, Nagaiyan; Umape, Prashant G; Patil, Sharad R

    2015-11-01

    4-Chloro-2-(diphenylamino)-1,3-thiazole-5-carbaldehyde was reacted with an active methylene compounds, cyanomethyl benzimidazole, cyanomethyl benzothiazole, barbituric acid and Meldrum's acid under Knoevenagel conditions to give novel push-pull styryl chromophores 8a-8d. The synthesized styryl chromophores were characterized by FT-IR, Mass and (1)H NMR spectral analysis. The photophysical characteristics of these styryl chromophores were evaluated. The effect of solvent polarity and viscosity on the absorption and emission properties of these chromophores was studied. The structural, molecular, electronic and photophysical parameters of the push-pull dyes were studied by using density functional theory (DFT) and time dependent density functional theory (TDDFT) computations. The ratio of the ground to the excited state dipole moment of the synthesized novel styryl dyes were calculated by Bakhshiev and Bilot-Kawski correlations.

  13. Evaluation of the computational effort for chromatic dispersion compensation in coherent optical PM-OFDM and PM-QAM systems.

    PubMed

    Poggiolini, P; Carena, A; Curri, V; Forghieri, F

    2009-02-02

    Recently, coherent-detection (CoD) polarization multiplexed (PM) transmission has attracted considerable interest, specifically as a possible solution for next-generation systems transmitting 100 Gb/s per channel and beyond. In this context, enabled by progress in ultra-fast digital signal processing (DSP) electronics, both multilevel phase/amplitude modulated formats (such as QAM) and orthogonal-frequency-division multiplexed (OFDM) formats have been proposed. One specific feature of DSP-supported CoD is the possibility of dealing with fiber chromatic dispersion (CD) electronically, either by post-filtering (PM-QAM) or by appropriately introducing symbol-duration redundancy (PM-OFDM). In both cases, ultra-long-haul fully uncompensated links seem to be possible. In this paper we estimate the computational effort required by CD compensation, when using the PM-QAM or PM-OFDM formats. Such effort, when expressed as number of operations per received bit, was found to be logarithmic with respect to link length, bit rate and fiber dispersion, for both classes of systems. We also found that PM-OFDM may have some advantage over PM-QAM, depending mostly on the over-sampling needed by the two systems. Asymptotically, for large channel memory and small over-sampling, the two systems tend to require the same CD-compensation computational effort. We also showed that the effort required by the mitigation of polarization-related effects can in principle be made small as compared to that of CD over long uncompensated links.

  14. Computational, spectral and structural studies of a new non linear optical crystal: 2-hydroxy pyridinium 3,5-dinitrobenzoate

    NASA Astrophysics Data System (ADS)

    Sathya, K.; Dhamodharan, P.; Dhandapani, M.

    2017-02-01

    An organic proton transfer compound, 2-hydroxy pyridinium 3,5-dinitrobenzoate (HPDA) was synthesized from 3,5-dinitro benzoic acid and 2 -hydroxy pyridine using methanol:acetone solvent mixture at room temperature and crystallized by solvent evaporation. UV-Vis, FT-IR, 1H, 13C and DEPT-135 NMR spectroscopic techniques, CHN analysis and TG-DTA were used for characterization. Single crystal XRD analysis was carried out to ascertain the molecular structure. Computational studies that include optimization of molecular geometry, natural bond analysis (NBO), Mulliken population analysis and HOMO-LUMO analysis were performed using Gaussian 09 software by B3LYP method at 6-31g basis set level. Hirshfeld analysis indicate O⋯H/H⋯O interactions are the prominent interactions confirming the presence of Nsbnd H⋯O, Osbnd H⋯O and Csbnd H⋯O hydrogen bonding.The second-order NLO property was assessed by Kurtz-Perry powder technique. Theoretical calculations indicate that hyperpolarizability of the crystal is 38 times greater than urea. The results show that the HPDA may be used for opto-electronic applications.

  15. Wavelength band optimization in spectral near-infrared optical tomography improves accuracy while reducing data acquisition and computational burden

    PubMed Central

    Eames, Matthew E.; Wang, Jia; Pogue, Brian W.; Dehghani, Hamid

    2013-01-01

    Multispectral near-infrared (NIR) tomographic imaging has the potential to provide information about molecules absorbing light in tissue, as well as subcellular structures scattering light, based on transmission measurements. However, the choice of possible wavelengths used is crucial for the accurate separation of these parameters, as well as for diminishing crosstalk between the contributing chromophores. While multispectral systems are often restricted by the wavelengths of laser diodes available, continuous-wave broadband systems exist that have the advantage of providing broadband NIR spectroscopy data, albeit without the benefit of the temporal data. In this work, the use of large spectral NIR datasets is analyzed, and an objective function to find optimal spectral ranges (windows) is examined. The optimally identified wavelength bands derived from this method are tested using both simulations and experimental data. It is found that the proposed method achieves images as qualitatively accurate as using the full spectrum, but improves crosstalk between parameters. Additionally, the judicious use of these spectral windows reduces the amount of data needed for full spectral tomographic imaging by 50%, therefore increasing computation time dramatically. PMID:19021417

  16. Submillisecond Optical Knife-Edge Testing

    NASA Technical Reports Server (NTRS)

    Thurlow, P.

    1983-01-01

    Fast computer-controlled sampling of optical knife-edge response (KER) signal increases accuracy of optical system aberration measurement. Submicrosecond-response detectors in optical focal plane convert optical signals to electrical signals converted to digital data, sampled and feed into computer for storage and subsequent analysis. Optical data are virtually free of effects of index-of-refraction gradients.

  17. Nonlinear Optics and Applications

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)

    2007-01-01

    Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.

  18. BerkeleyGW: A massively parallel computer package for the calculation of the quasiparticle and optical properties of materials and nanostructures

    NASA Astrophysics Data System (ADS)

    Deslippe, Jack; Samsonidze, Georgy; Strubbe, David A.; Jain, Manish; Cohen, Marvin L.; Louie, Steven G.

    2012-06-01

    BerkeleyGW is a massively parallel computational package for electron excited-state properties that is based on the many-body perturbation theory employing the ab initio GW and GW plus Bethe-Salpeter equation methodology. It can be used in conjunction with many density-functional theory codes for ground-state properties, including PARATEC, PARSEC, Quantum ESPRESSO, SIESTA, and Octopus. The package can be used to compute the electronic and optical properties of a wide variety of material systems from bulk semiconductors and metals to nanostructured materials and molecules. The package scales to 10 000s of CPUs and can be used to study systems containing up to 100s of atoms. Program summaryProgram title: BerkeleyGW Catalogue identifier: AELG_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AELG_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Open source BSD License. See code for licensing details. No. of lines in distributed program, including test data, etc.: 576 540 No. of bytes in distributed program, including test data, etc.: 110 608 809 Distribution format: tar.gz Programming language: Fortran 90, C, C++, Python, Perl, BASH Computer: Linux/UNIX workstations or clusters Operating system: Tested on a variety of Linux distributions in parallel and serial as well as AIX and Mac OSX RAM: (50-2000) MB per CPU (Highly dependent on system size) Classification: 7.2, 7.3, 16.2, 18 External routines: BLAS, LAPACK, FFTW, ScaLAPACK (optional), MPI (optional). All available under open-source licenses. Nature of problem: The excited state properties of materials involve the addition or subtraction of electrons as well as the optical excitations of electron-hole pairs. The excited particles interact strongly with other electrons in a material system. This interaction affects the electronic energies, wavefunctions and lifetimes. It is well known that ground-state theories, such as standard methods

  19. Comparisons of the diagnostic accuracies of optical coherence tomography, micro-computed tomography, and histology in periodontal disease: an ex vivo study

    PubMed Central

    2017-01-01

    Purpose Optical coherence tomography (OCT) is a noninvasive diagnostic technique that may be useful for both qualitative and quantitative analyses of the periodontium. Micro-computed tomography (micro-CT) is another noninvasive imaging technique capable of providing submicron spatial resolution. The purpose of this study was to present periodontal images obtained using ex vivo dental OCT and to compare OCT images with micro-CT images and histologic sections. Methods Images of ex vivo canine periodontal structures were obtained using OCT. Biologic depth measurements made using OCT were compared to measurements made on histologic sections prepared from the same sites. Visual comparisons were made among OCT, micro-CT, and histologic sections to evaluate whether anatomical details were accurately revealed by OCT. Results The periodontal tissue contour, gingival sulcus, and the presence of supragingival and subgingival calculus could be visualized using OCT. OCT was able to depict the surface topography of the dentogingival complex with higher resolution than micro-CT, but the imaging depth was typically limited to 1.2–1.5 mm. Biologic depth measurements made using OCT were a mean of 0.51 mm shallower than the histologic measurements. Conclusions Dental OCT as used in this study was able to generate high-resolution, cross-sectional images of the superficial portions of periodontal structures. Improvements in imaging depth and the development of an intraoral sensor are likely to make OCT a useful technique for periodontal applications. PMID:28261522

  20. Computational fluid dynamics comparisons of wall shear stress in patient-specific coronary artery bifurcation using coronary angiography and optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Poon, Eric; Thondapu, Vikas; Chin, Cheng; Scheerlinck, Cedric; Zahtila, Tony; Mamon, Chris; Nguyen, Wilson; Ooi, Andrew; Barlis, Peter

    2016-11-01

    Blood flow dynamics directly influence biology of the arterial wall, and are closely linked with the development of coronary artery disease. Computational fluid dynamics (CFD) solvers may be employed to analyze the hemodynamic environment in patient-specific reconstructions of coronary arteries. Although coronary X-ray angiography (CA) is the most common medical imaging modality for 3D arterial reconstruction, models reconstructed from CA assume a circular or elliptical cross-sectional area. This limitation can be overcome with a reconstruction technique fusing CA with intravascular optical coherence tomography (OCT). OCT scans the interior of an artery using near-infrared light, achieving a 10-micron resolution and providing unprecedented detail of vessel geometry. We compared 3D coronary artery bifurcation models generated using CA alone versus OCT-angiography fusion. The model reconstructed from CA alone is unable to identify the detailed geometrical variations of diseased arteries, and also under-estimates the cross-sectional vessel area compared to OCT-angiography fusion. CFD was performed in both models under pulsatile flow in order to identify and compare regions of low wall shear stress, a hemodynamic parameter directly linked with progression of atherosclerosis. Supported by ARC LP150100233 and VLSCI VR0210.

  1. A study on the reproducibility and spatial uniformity of N-isopropylacrylamide polymer gel dosimetry using a commercial 10X fast optical-computed tomography scanner

    NASA Astrophysics Data System (ADS)

    Chang, Y. J.; Lin, J. Q.; Hsieh, B. T.; Chen, C. H.

    2013-06-01

    This study investigated the reproducibility and spatial uniformity of N-isopropylacrylamide (NIPAM) polymer gel as well as the reproducibility of a NIPAM polymer gel dosimeter. A commercial 10X fast optical computed tomography scanner (OCTOPUS-10X, MGS Research, Inc., Madison, CT, USA) was used as the readout tool of the NIPAM polymer gel dosimeter. A cylindrical NIPAM gel phantom measuring 10 cm (diameter) by 10 cm (height) by 3 mm (thickness) was irradiated by the four-field box treatment with a field size of 3 cm × 3 cm. The dose profiles were found to be consistent at the depths of 2.0 cm to 5.0 cm for two independent gel phantom batches, and the average uncertainty was less than 2%. The gamma pass rates were calculated to be between 94% and 95% at depths of 40 mm for two independent gel phantom batches using 4% dose difference and 4 mm distance-to-agreement criterion. The NIPAM polymer gel dosimeter was highly reproducible and spatially uniform. The results highlighted the potential of the NIPAM polymer gel dosimeter in radiotherapy.

  2. Biomechanics of the chick embryonic heart outflow tract at HH18 using 4D optical coherence tomography imaging and computational modeling.

    PubMed

    Liu, Aiping; Yin, Xin; Shi, Liang; Li, Peng; Thornburg, Kent L; Wang, Ruikang; Rugonyi, Sandra

    2012-01-01

    During developmental stages, biomechanical stimuli on cardiac cells modulate genetic programs, and deviations from normal stimuli can lead to cardiac defects. Therefore, it is important to characterize normal cardiac biomechanical stimuli during early developmental stages. Using the chicken embryo model of cardiac development, we focused on characterizing biomechanical stimuli on the Hamburger-Hamilton (HH) 18 chick cardiac outflow tract (OFT), the distal portion of the heart from which a large portion of defects observed in humans originate. To characterize biomechanical stimuli in the OFT, we used a combination of in vivo optical coherence tomography (OCT) imaging, physiological measurements and computational fluid dynamics (CFD) modeling. We found that, at HH18, the proximal portion of the OFT wall undergoes larger circumferential strains than its distal portion, while the distal portion of the OFT wall undergoes larger wall stresses. Maximal wall shear stresses were generally found on the surface of endocardial cushions, which are protrusions of extracellular matrix onto the OFT lumen that later during development give rise to cardiac septa and valves. The non-uniform spatial and temporal distributions of stresses and strains in the OFT walls provide biomechanical cues to cardiac cells that likely aid in the extensive differential growth and remodeling patterns observed during normal development.

  3. Modules and methods for all photonic computing

    DOEpatents

    Schultz, David R.; Ma, Chao Hung

    2001-01-01

    A method for all photonic computing, comprising the steps of: encoding a first optical/electro-optical element with a two dimensional mathematical function representing input data; illuminating the first optical/electro-optical element with a collimated beam of light; illuminating a second optical/electro-optical element with light from the first optical/electro-optical element, the second optical/electro-optical element having a characteristic response corresponding to an iterative algorithm useful for solving a partial differential equation; iteratively recirculating the signal through the second optical/electro-optical element with light from the second optical/electro-optical element for a predetermined number of iterations; and, after the predetermined number of iterations, optically and/or electro-optically collecting output data representing an iterative optical solution from the second optical/electro-optical element.

  4. Optical Inference Machines

    DTIC Science & Technology

    1988-06-27

    de olf nessse end Id e ;-tl Sb ieeI smleo) ,Optical Artificial Intellegence ; Optical inference engines; Optical logic; Optical informationprocessing...common. They arise in areas such as expert systems and other artificial intelligence systems. In recent years, the computer science language PROLOG has...cal processors should in principle be well suited for : I artificial intelligence applications. In recent years, symbolic logic processing. , the

  5. Performance Enhancement in Optical Computing.

    DTIC Science & Technology

    1998-06-01

    data pulse width, however, increasing the bandwidth beyond that does not give 8 much benefit in terms of bit error rate. Therefore, in terms of the...Processing and Holography in Meriden , NH, June, 1997 (J.F. Walkup). 9. Attended 1997 SPIE Technical Symposium, San Diego, July 1997 (T.F. Krile and J.F...filter and three pulse model is in good agreement with the simulation results. The only big error occurs when the system bandwidth is infinity. In

  6. Computer Aided Geometrical Optics Design.

    DTIC Science & Technology

    1983-12-01

    calculate wavefront aberrations. Zernike polynomials are defined on the unit circle. For exit pupil geometries other than circular, presumably the FALCON...object to the first surface can be specified as any distance but if none is specified, the default value is 10 10 units . The Y-Z plane is taken as the...Figure 2-2. LENS LI SINGLE THIN LENS EXAMPLE SAY 10 SCY -5 TH 50 UNITS CM CV .01 TH 2 SCHOTT BK7 RD 200 TH 500 GLASS 1.0 END Figure 2-2. Single Thin

  7. The Computer Bulletin Board.

    ERIC Educational Resources Information Center

    Batt, Russell H., Ed.

    1990-01-01

    Four applications of microcomputers in the chemical laboratory are presented. Included are "Mass Spectrometer Interface with an Apple II Computer,""Interfacing the Spectronic 20 to a Computer,""A pH-Monitoring and Control System for Teaching Laboratories," and "A Computer-Aided Optical Melting Point Device." Software, instrumentation, and uses are…

  8. Optic glioma

    MedlinePlus

    Glioma - optic; Optic nerve glioma; Juvenile pilocytic astrocytoma; Brain cancer - optic glioma ... Optic gliomas are rare. The cause of optic gliomas is unknown. Most optic gliomas are slow-growing ...

  9. Development of an Aero-Optics Software Library and Integration into Structured Overset and Unstructured Computational Fluid Dynamics (CFD) Flow Solvers

    DTIC Science & Technology

    2011-04-01

    integrated within OVERFLOW and AVUS, and demonstrated for evaluating the Aero-Optical propagation through unsteady, turbulent flows past a circular ...Optical Path Difference-based Wavefront Error Processing 11 10 Demonstration: Unsteady Flow Past a Circular Cylinder 12 11 Validation: 1 Foot Conformal...time step of an unsteady DES calculation . . . . . . . . . . . . . . . . . . . . . 9 5 Unsteady flow past a circular cylinder. Entropy measure

  10. Qubus computation

    NASA Astrophysics Data System (ADS)

    Munro, W. J.; Nemoto, Kae; Spiller, T. P.; van Loock, P.; Braunstein, Samuel L.; Milburn, G. J.

    2006-08-01

    Processing information quantum mechanically is known to enable new communication and computational scenarios that cannot be accessed with conventional information technology (IT). We present here a new approach to scalable quantum computing---a "qubus computer"---which realizes qubit measurement and quantum gates through interacting qubits with a quantum communication bus mode. The qubits could be "static" matter qubits or "flying" optical qubits, but the scheme we focus on here is particularly suited to matter qubits. Universal two-qubit quantum gates may be effected by schemes which involve measurement of the bus mode, or by schemes where the bus disentangles automatically and no measurement is needed. This approach enables a parity gate between qubits, mediated by a bus, enabling near-deterministic Bell state measurement and entangling gates. Our approach is therefore the basis for very efficient, scalable QIP, and provides a natural method for distributing such processing, combining it with quantum communication.

  11. Optical Circuitry Cooperative

    NASA Astrophysics Data System (ADS)

    Gibbs, H. M.; Gibson, U.; Peyghambarian, N.; Sarid, D.; Stegeman, G.

    1985-01-01

    An Optical Circuitry Cooperative (OCC) has been formed as an NSF cooperative research center in which six or more companies contribute financial support; NSF provides support which declines to zero in five years. Companies benefit from a center by early access to research results, leverage for their research dollars, participation in research selection, and improved relations with faculty and students. The university receives support for a major research program that increases its research capability, provides reasonably stable funding, and opens more opportunities for graduate students. The potential of optical circuitry has been discussed for many years, but the excitement is growing rapidly on the strength of the success of optical fibers for optical transmission, the generation of subpicosecond opitcal pulses, and the development of promising optical logic elements, such as optical bistable devices. And yet, much research remains to be done to discover the best nonlinear optical materials and fabrication techniques. OCC will perform research to provide a data base to allow the development of optical circuitry devices. The areas encompassed by OCC include all-optical logic, picosecond decision-making, guided-wave preprocessors, opti-cal interconnects within computers (both fiber and whole-array imaging), optical storage, and optical computer architecture and devices.

  12. Digital optical conversion module

    DOEpatents

    Kotter, Dale K.; Rankin, Richard A.

    1991-02-26

    A digital optical conversion module used to convert an analog signal to a computer compatible digital signal including a voltage-to-frequency converter, frequency offset response circuitry, and an electrical-to-optical converter. Also used in conjunction with the digital optical conversion module is an optical link and an interface at the computer for converting the optical signal back to an electrical signal. Suitable for use in hostile environments having high levels of electromagnetic interference, the conversion module retains high resolution of the analog signal while eliminating the potential for errors due to noise and interference. The module can be used to link analog output scientific equipment such as an electrometer used with a mass spectrometer to a computer.

  13. Digital optical conversion module

    DOEpatents

    Kotter, D.K.; Rankin, R.A.

    1988-07-19

    A digital optical conversion module used to convert an analog signal to a computer compatible digital signal including a voltage-to-frequency converter, frequency offset response circuitry, and an electrical-to-optical converter. Also used in conjunction with the digital optical conversion module is an optical link and an interface at the computer for converting the optical signal back to an electrical signal. Suitable for use in hostile environments having high levels of electromagnetic interference, the conversion module retains high resolution of the analog signal while eliminating the potential for errors due to noise and interference. The module can be used to link analog output scientific equipment such as an electrometer used with a mass spectrometer to a computer. 2 figs.

  14. Fiber Optics: No Illusion.

    ERIC Educational Resources Information Center

    American School and University, 1983

    1983-01-01

    A campus computer center at Hofstra University (New York) that holds 70 terminals for student use was first a gymnasium, then a language laboratory. Strands of fiber optics are used for the necessary wiring. (MLF)

  15. Improved Optical Keyboard

    NASA Technical Reports Server (NTRS)

    Jamieson, R. S.

    1985-01-01

    Optical keyboard surfaces used in typewriters, computer terminals, and telephone inexpensively fabricated using stack of printed-circuit cards set in laminate. Internal laminations carry all illuminating and sensing light conductors to keys.

  16. Hybrid Optical Inference Machines

    DTIC Science & Technology

    1991-09-27

    Mitsunaga, and K. Kyuma, "GaAs/AlGaAs Optical Synaptic Interconnection Device for Neural Networks,ŗ Opt. Lett. 14, 844-846 (1989). 8. Y. Nitta, J. Ohta, K...tautologies (step .t above) is computationally chne) using both neural network and symbolic substtution the most significant step of the optical resolution...the-theories of connectionistic ( neural net- Derstine and Guha consider PARLOG, a version of PRO- work) computing offer several opportunities for

  17. Beam optics test stand

    NASA Astrophysics Data System (ADS)

    Humphries, S., Jr.; Hess, G.

    1988-04-01

    The design and construction of the Beam Optics Test Stand (BOTS) is presented. A variety of computer compatible diagnostics has been developed to facilitate experiments. Extensive theoretical work is presented leading to the identification of two potential methods to correct aberrations in magnetic optics: biased grid arrays and space charge corrected solenoidal lenses. A series of experiments is presented which demonstrates, for the first time, the feasibility of space charge corrected optics.

  18. Apollo Ring Optical Switch

    SciTech Connect

    Maestas, J.H.

    1987-03-01

    An optical switch was designed, built, and installed at Sandia National Laboratories in Albuquerque, New Mexico, to facilitate the integration of two Apollo computer networks into a single network. This report presents an overview of the optical switch as well as its layout, switch testing procedure and test data, and installation.

  19. Quantum teleportation of optical quantum gates.

    PubMed

    Bartlett, Stephen D; Munro, William J

    2003-03-21

    We show that a universal set of gates for quantum computation with optics can be quantum teleported through the use of EPR entangled states, homodyne detection, and linear optics and squeezing operations conditioned on measurement outcomes. This scheme may be used for fault-tolerant quantum computation in any optical scheme (qubit or continuous-variable). The teleportation of nondeterministic nonlinear gates employed in linear optics quantum computation is discussed.

  20. The New Physical Optics Notebook: Tutorials in Fourier Optics.

    ERIC Educational Resources Information Center

    Reynolds, George O.; And Others

    This is a textbook of Fourier optics for the classroom or self-study. Major topics included in the 38 chapters are: Huygens' principle and Fourier transforms; image formation; optical coherence theory; coherent imaging; image analysis; coherent noise; interferometry; holography; communication theory techniques; analog optical computing; phase…

  1. Optical vortex beam based optical fan for high-precision optical measurements and optical switching.

    PubMed

    Zhou, Zhi-Yuan; Li, Yan; Ding, Dong-Sheng; Zhang, Wei; Shi, Shuai; Shi, Bao-Sen

    2014-09-01

    The polarization and orbital angular momentum properties of light are of great importance in optical science and technology in the fields of high-precision optical measurements and high-capacity and high-speed optical communications. Here we show a method for the construction of a simple and robust scheme to rotate a light beam such as a fan, which is based on a combination of these two properties and using the thermal-dispersion and electro-optical effect of birefringent crystals. Using a computer-based digital image-processing technique, we determine the temperature and thermal-dispersion difference of the crystal with high resolution. We also use the rotation phenomenon to realize thermo-optic and electro-optic switches. The basic operating principles for measurement and switching processes are presented in detail. The methods developed here will have wide practical applicability in various fields, including remote sensing, materials science, and optical communication networks.

  2. Optical controlled keyboard system

    NASA Astrophysics Data System (ADS)

    Budzyński, Łukasz; Długosz, Dariusz; Niewiarowski, Bartosz; Zajkowski, Maciej

    2011-06-01

    Control systems of our computers are common devices, based on the manipulation of keys or a moving ball. Completely healthy people have no problems with the operation of such devices. Human disability makes everyday activities become a challenge and create trouble. When a man can not move his hands, the work becomes difficult or often impossible. Controlled optical keyboard is a modern device that allows to bypass the limitations of disability limbs. The use of wireless optical transmission allows to control computer using a laser beam, which cooperates with the photodetectors. The article presents the construction and operation of non-contact optical keyboard for people with disabilities.

  3. Fiber Optics and Library Technology.

    ERIC Educational Resources Information Center

    Koenig, Michael

    1984-01-01

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

  4. Optical interconnection techniques for Hypercube

    NASA Technical Reports Server (NTRS)

    Johnston, A. R.; Bergman, L. A.; Wu, W. H.

    1988-01-01

    Direct free-space optical interconnection techniques are described for the Hypercube concurrent processor machine using a holographic optical element. Computational requirements and optical constraints on implementation are briefly summarized with regard to topology, power consumption, and available technologies. A hybrid lens/HOE approach is described that can support an eight-dimensional cube of 256 nodes.

  5. Optical Character Recognition.

    ERIC Educational Resources Information Center

    Converso, L.; Hocek, S.

    1990-01-01

    This paper describes computer-based optical character recognition (OCR) systems, focusing on their components (the computer, the scanner, the OCR, and the output device); how the systems work; and features to consider in selecting a system. A list of 26 questions to ask to evaluate systems for potential purchase is included. (JDD)

  6. Computational mechanics

    SciTech Connect

    Raboin, P J

    1998-01-01

    The Computational Mechanics thrust area is a vital and growing facet of the Mechanical Engineering Department at Lawrence Livermore National Laboratory (LLNL). This work supports the development of computational analysis tools in the areas of structural mechanics and heat transfer. Over 75 analysts depend on thrust area-supported software running on a variety of computing platforms to meet the demands of LLNL programs. Interactions with the Department of Defense (DOD) High Performance Computing and Modernization Program and the Defense Special Weapons Agency are of special importance as they support our ParaDyn project in its development of new parallel capabilities for DYNA3D. Working with DOD customers has been invaluable to driving this technology in directions mutually beneficial to the Department of Energy. Other projects associated with the Computational Mechanics thrust area include work with the Partnership for a New Generation Vehicle (PNGV) for ''Springback Predictability'' and with the Federal Aviation Administration (FAA) for the ''Development of Methodologies for Evaluating Containment and Mitigation of Uncontained Engine Debris.'' In this report for FY-97, there are five articles detailing three code development activities and two projects that synthesized new code capabilities with new analytic research in damage/failure and biomechanics. The article this year are: (1) Energy- and Momentum-Conserving Rigid-Body Contact for NIKE3D and DYNA3D; (2) Computational Modeling of Prosthetics: A New Approach to Implant Design; (3) Characterization of Laser-Induced Mechanical Failure Damage of Optical Components; (4) Parallel Algorithm Research for Solid Mechanics Applications Using Finite Element Analysis; and (5) An Accurate One-Step Elasto-Plasticity Algorithm for Shell Elements in DYNA3D.

  7. Smart time-pulse coding photoconverters as basic components 2D-array logic devices for advanced neural networks and optical computers

    NASA Astrophysics Data System (ADS)

    Krasilenko, Vladimir G.; Nikolsky, Alexander I.; Lazarev, Alexander A.; Michalnichenko, Nikolay N.

    2004-04-01

    The article deals with a conception of building arithmetic-logic devices (ALD) with a 2D-structure and optical 2D-array inputs-outputs as advanced high-productivity parallel basic operational training modules for realization of basic operation of continuous, neuro-fuzzy, multilevel, threshold and others logics and vector-matrix, vector-tensor procedures in neural networks, that consists in use of time-pulse coding (TPC) architecture and 2D-array smart optoelectronic pulse-width (or pulse-phase) modulators (PWM or PPM) for transformation of input pictures. The input grayscale image is transformed into a group of corresponding short optical pulses or time positions of optical two-level signal swing. We consider optoelectronic implementations of universal (quasi-universal) picture element of two-valued ALD, multi-valued ALD, analog-to-digital converters, multilevel threshold discriminators and we show that 2D-array time-pulse photoconverters are the base elements for these devices. We show simulation results of the time-pulse photoconverters as base components. Considered devices have technical parameters: input optical signals power is 200nW_200μW (if photodiode responsivity is 0.5A/W), conversion time is from tens of microseconds to a millisecond, supply voltage is 1.5_15V, consumption power is from tens of microwatts to a milliwatt, conversion nonlinearity is less than 1%. One cell consists of 2-3 photodiodes and about ten CMOS transistors. This simplicity of the cells allows to carry out their integration in arrays of 32x32, 64x64 elements and more.

  8. Optical Data Library {number_sign}5 for use with the WINDOW 4.1 computer program including NFRC certified data

    SciTech Connect

    Rubin, M.

    1998-01-01

    This report contains additional data for 783 glazing products that can be used with the Window 4.1 energy analysis program. The NFRC requires that all simulations must be carried out using NFRC-certified optical data only. Solar heat gain coefficient and visible transmittance must be calculated using spectral transmittance and reflectance in the solar range. U-factor calculations must use spectral or integrated emittance. NFRC-certified data within the Window 4.1 program is indicated.

  9. Atmospheric optical calibration system

    DOEpatents

    Hulstrom, R.L.; Cannon, T.W.

    1988-10-25

    An atmospheric optical calibration system is provided to compare actual atmospheric optical conditions to standard atmospheric optical conditions on the basis of aerosol optical depth, relative air mass, and diffuse horizontal skylight to global horizontal photon flux ratio. An indicator can show the extent to which the actual conditions vary from standard conditions. Aerosol scattering and absorption properties, diffuse horizontal skylight to global horizontal photon flux ratio, and precipitable water vapor determined on a real-time basis for optical and pressure measurements are also used to generate a computer spectral model and for correcting actual performance response of a photovoltaic device to standard atmospheric optical condition response on a real-time basis as the device is being tested in actual outdoor conditions. 7 figs.

  10. Atmospheric optical calibration system

    DOEpatents

    Hulstrom, Roland L.; Cannon, Theodore W.

    1988-01-01

    An atmospheric optical calibration system is provided to compare actual atmospheric optical conditions to standard atmospheric optical conditions on the basis of aerosol optical depth, relative air mass, and diffuse horizontal skylight to global horizontal photon flux ratio. An indicator can show the extent to which the actual conditions vary from standard conditions. Aerosol scattering and absorption properties, diffuse horizontal skylight to global horizontal photon flux ratio, and precipitable water vapor determined on a real-time basis for optical and pressure measurements are also used to generate a computer spectral model and for correcting actual performance response of a photovoltaic device to standard atmospheric optical condition response on a real-time basis as the device is being tested in actual outdoor conditions.

  11. Automation of optical tweezers

    NASA Astrophysics Data System (ADS)

    Hsieh, Tseng-Ming; Chang, Bo-Jui; Hsu, Long

    2000-07-01

    Optical tweezers is a newly developed instrument, which makes possible the manipulation of micro-optical particles under a microscope. In this paper, we present the automation of an optical tweezers which consists of a modified optical tweezers, equipped with two motorized actuators to deflect a 1 W argon laser beam, and a computer control system including a joystick. The trapping of a single bead and a group of lactoacidofilus was shown, separately. With the aid of the joystick and two auxiliary cursers superimposed on the real-time image of a trapped bead, we demonstrated the simple and convenient operation of the automated optical tweezers. By steering the joystick and then pressing a button on it, we assign a new location for the trapped bead to move to. The increment of the motion 0.04 (mu) m for a 20X objective, is negligible. With a fast computer for image processing, the manipulation of the trapped bead is smooth and accurate. The automation of the optical tweezers is also programmable. This technique may be applied to accelerate the DNA hybridization in a gene chip. The combination of the modified optical tweezers with the computer control system provides a tool for precise manipulation of micro particles in many scientific fields.

  12. Optical closure of parameterized bio-optical relationships

    NASA Astrophysics Data System (ADS)

    He, Shuangyan; Fischer, Jürgen; Schaale, Michael; He, Ming-xia

    2014-03-01

    An optical closure study on bio-optical relationships was carried out using radiative transfer model matrix operator method developed by Freie Universität Berlin. As a case study, the optical closure of bio-optical relationships empirically parameterized with in situ data for the East China Sea was examined. Remote-sensing reflectance ( R rs) was computed from the inherent optical properties predicted by these biooptical relationships and compared with published in situ data. It was found that the simulated R rs was overestimated for turbid water. To achieve optical closure, bio-optical relationships for absorption and scattering coefficients for suspended particulate matter were adjusted. Furthermore, the results show that the Fournier and Forand phase functions obtained from the adjusted relationships perform better than the Petzold phase function. Therefore, before bio-optical relationships are used for a local sea area, the optical closure should be examined.

  13. Laser beam modeling in optical storage systems

    NASA Technical Reports Server (NTRS)

    Treptau, J. P.; Milster, T. D.; Flagello, D. G.

    1991-01-01

    A computer model has been developed that simulates light propagating through an optical data storage system. A model of a laser beam that originates at a laser diode, propagates through an optical system, interacts with a optical disk, reflects back from the optical disk into the system, and propagates to data and servo detectors is discussed.

  14. Summaries of Papers Presented at the Topical Meeting on Optical Computing Held in Incline Village, Nevada on March 16-18, 1987.

    DTIC Science & Technology

    1988-03-31

    Jean F. Morhange, Hyatt M. Gibbs, Nasser - TuD7 Passive Single-Mode Optical Networks for Cohe- Peyghambarian, U. Arizona; Feng-Yu Juang, Pallab K... Piaget and C. Lemonier of LEP for lending the microchannel plate image intensifiers used in the experiment. Pehrenc-s: 1. G.M. Morris, Opt. Engin. 24,86...ME? Monro. D, M. -- TuE9 Cri, A t A6 Morhange. Jean F. .- TuE5% U’iltoll P S MD2 Morris. G. Michael -MD8 Murdlocca. M. J,.- MB20 Haobihy. 5 F. MD5

  15. Comparison between ray-tracing and physical optics for the computation of light absorption in capillaries--the influence of diffraction and interference.

    PubMed

    Qin, Yuan; Michalowski, Andreas; Weber, Rudolf; Yang, Sen; Graf, Thomas; Ni, Xiaowu

    2012-11-19

    Ray-tracing is the commonly used technique to calculate the absorption of light in laser deep-penetration welding or drilling. Since new lasers with high brilliance enable small capillaries with high aspect ratios, diffraction might become important. To examine the applicability of the ray-tracing method, we studied the total absorptance and the absorbed intensity of polarized beams in several capillary geometries. The ray-tracing results are compared with more sophisticated simulations based on physical optics. The comparison shows that the simple ray-tracing is applicable to calculate the total absorptance in triangular grooves and in conical capillaries but not in rectangular grooves. To calculate the distribution of the absorbed intensity ray-tracing fails due to the neglected interference, diffraction, and the effects of beam propagation in the capillaries with sub-wavelength diameter. If diffraction is avoided e.g. with beams smaller than the entrance pupil of the capillary or with very shallow capillaries, the distribution of the absorbed intensity calculated by ray-tracing corresponds to the local average of the interference pattern found by physical optics.

  16. Optical design at APL

    NASA Astrophysics Data System (ADS)

    Harris, Terry J.

    1988-12-01

    An account is given of the sophisticated software tools currently available for the numerical support of increasingly complex optical design and analysis tasks. Such computer-aided engineering resources allow ray-tracing, aberration analyses, and such lens characterizations as modulation-transfer and point-spread functions to be quickly and accurately conducted. Illustrative applications of these techniques are presented for the fields of reflecting telescope, IR optics, and spectrometer design, as well as achromat design and stray-light analysis.

  17. Scattering from binary optics

    NASA Technical Reports Server (NTRS)

    Ricks, Douglas W.

    1993-01-01

    There are a number of sources of scattering in binary optics: etch depth errors, line edge errors, quantization errors, roughness, and the binary approximation to the ideal surface. These sources of scattering can be systematic (deterministic) or random. In this paper, scattering formulas for both systematic and random errors are derived using Fourier optics. These formulas can be used to explain the results of scattering measurements and computer simulations.

  18. Computers and Computer Resources.

    ERIC Educational Resources Information Center

    Bitter, Gary

    1980-01-01

    This resource directory provides brief evaluative descriptions of six popular home computers and lists selected sources of educational software, computer books, and magazines. For a related article on microcomputers in the schools, see p53-58 of this journal issue. (SJL)

  19. User's guide to HELIOS: A computer program for modeling the optical behavior of reflecting solar concentrators. Part 1: Introduction and code input

    NASA Astrophysics Data System (ADS)

    Vittitoe, C. N.; Biggs, F.

    1981-08-01

    HELIOS is a flexible computer code for evaluating designs for central receiver, parabolic dish, and other reflecting solar energy collector systems, for safety calculations on the threat to personnel and to the facility itself, for determination of how various input parameters alter the power collected, for design trade offs, and for heliostat evaluations. Input variables include atmospheric transmission effects, reflector shape and surface errors, suntracking errors, focusing and alignment strategies, receiver design, placement positions of the tower and mirrors, and time of day and day of the year for the calculation. Complete input instructions and a description of the code structure are given.

  20. Optic flow and autonomous navigation.

    PubMed

    Campani, M; Giachetti, A; Torre, V

    1995-01-01

    Many animals, especially insects, compute and use optic flow to control their motion direction and to avoid obstacles. Recent advances in computer vision have shown that an adequate optic flow can be computed from image sequences. Therefore studying whether artificial systems, such as robots, can use optic flow for similar purposes is of particular interest. Experiments are reviewed that suggest the possible use of optic flow for the navigation of a robot moving in indoor and outdoor environments. The optic flow is used to detect and localise obstacles in indoor scenes, such as corridors, offices, and laboratories. These routines are based on the computation of a reduced optic flow. The robot is usually able to avoid large obstacles such as a chair or a person. The avoidance performances of the proposed algorithm critically depend on the optomotor reaction of the robot. The optic flow can be used to understand the ego-motion in outdoor scenes, that is, to obtain information on the absolute velocity of the moving vehicle and to detect the presence of other moving objects. A critical step is the correction of the optic flow for shocks and vibrations present during image acquisition. The results obtained suggest that optic flow can be successfully used by biological and artificial systems to control their navigation. Moreover, both systems require fast and accurate optomotor reactions and need to compensate for the instability of the viewed world.

  1. Theoretical Optics: An Introduction

    NASA Astrophysics Data System (ADS)

    Römer, Hartmann

    2005-02-01

    Starting from basic electrodynamics, this volume provides a solid, yet concise introduction to theoretical optics, containing topics such as nonlinear optics, light-matter interaction, and modern topics in quantum optics, including entanglement, cryptography, and quantum computation. The author, with many years of experience in teaching and research, goes way beyond the scope of traditional lectures, enabling readers to keep up with the current state of knowledge. Both content and presentation make it essential reading for graduate and phD students as well as a valuable reference for researchers.

  2. Proposal, verification and comparison of three computer image analysis methods for detection and evaluation of colour glaucomatous changes within the optic disc of a human eye retina

    NASA Astrophysics Data System (ADS)

    Pluhacek, Frantisek; Pospisil, Jaroslav

    2005-04-01

    The typical symptom of the human eye glaucoma is a rise and a progression of the bright area (named pallor area) within the retina blind spot. The image analysis manner proposed by the authors detects and suitably numerically describes the relative size of the representative pallor area in the colour digital image of the retina obtained by a suitable fundus camera connected with the computer. Three new different computer image analysis statistical methods for experimental diagnostic evaluation of the obtained characteristic data are proposed in this article: the quantile curves method, the neural net method and the probability density curves method. The quantile curves method is based on the graphical comparison of a relative representative pallor area size with its determined normal value. The neural net and probability density curves methods can automatically and objectively classify the investigated eyes in exactly defined glaucoma risk classes and diagnosed glaucoma with the rated probabilities of incorrect diagnosis determination. All mentioned methods are verified and mutually compared by their application to the large statistical sets of human retina images of various healthy and glaucomatous subjects.

  3. [Investigation of influencing variables on the computer-aided simulation of contacts in dynamic occlusion based on optically digitized plaster casts].

    PubMed

    Böröcz, Z; Dirksen, D; Thomas, C; Runte, C; Bollmann, F; von Bally, G

    2004-05-01

    In dentistry, mechanical articulators with which mandibular movements can be reproduced in dentals casts play a major role. Commonly used semiadjustable articulators, however, have major limitations: On the one hand, the movement of the mandible is not reproduced exactly, on the other, they do not provide time-related information on jaw movement. Both problems can be solved by replacing the mechanical articulator by a digital simulation ("virtual articulator") based on digitized plaster casts and electronically recorded masticatory movements. We present a system for the 3D measurement of plaster casts in a skull-related, anatomical coordinate system using the fringe projection technique, and electronically recorded condylar movements. Using numerical algorithms, the contacts between upper and low jaw, and the angle of rotation of the temporomandibular joint can be computed for each movement in dynamic occlusion. Taking the data recorded from a patient as an example, the influence of the accuracy of the digitization of plaster casts on the computation of the rotation of the temporomandibular joint is discussed in relation to the anatomy of the masticatory apparatus.

  4. Optic neuritis

    MedlinePlus

    ... optic neuritis is unknown. The optic nerve carries visual information from your eye to the brain. The ... brain , including special images of the optic nerve Visual acuity testing Visual field testing Examination of the ...

  5. Single layer lead iodide: computational exploration of structural, electronic and optical properties, strain induced band modulation and the role of spin-orbital-coupling

    NASA Astrophysics Data System (ADS)

    Zhou, Mei; Duan, Wenhui; Chen, Ying; Du, Aijun

    2015-09-01

    Graphitic like layered materials exhibit intriguing electronic structures and thus the search for new types of two-dimensional (2D) monolayer materials is of great interest for developing novel nano-devices. By using density functional theory (DFT) method, here we for the first time investigate the structure, stability, electronic and optical properties of monolayer lead iodide (PbI2). The stability of PbI2 monolayer is first confirmed by phonon dispersion calculation. Compared to the calculation using generalized gradient approximation, screened hybrid functional and spin-orbit coupling effects can not only predicts an accurate bandgap (2.63 eV), but also the correct position of valence and conduction band edges. The biaxial strain can tune its bandgap size in a wide range from 1 eV to 3 eV, which can be understood by the strain induced uniformly change of electric field between Pb and I atomic layer. The calculated imaginary part of the dielectric function of 2D graphene/PbI2 van der Waals type hetero-structure shows significant red shift of absorption edge compared to that of a pure monolayer PbI2. Our findings highlight a new interesting 2D material with potential applications in nanoelectronics and optoelectronics.Graphitic like layered materials exhibit intriguing electronic structures and thus the search for new types of two-dimensional (2D) monolayer materials is of great interest for developing novel nano-devices. By using density functional theory (DFT) method, here we for the first time investigate the structure, stability, electronic and optical properties of monolayer lead iodide (PbI2). The stability of PbI2 monolayer is first confirmed by phonon dispersion calculation. Compared to the calculation using generalized gradient approximation, screened hybrid functional and spin-orbit coupling effects can not only predicts an accurate bandgap (2.63 eV), but also the correct position of valence and conduction band edges. The biaxial strain can tune its

  6. Synthesis, crystal structure, spectroscopic characterization and nonlinear optical properties of manganese (II) complex of picolinate: A combined experimental and computational study

    NASA Astrophysics Data System (ADS)

    Tamer, Ömer; Avcı, Davut; Atalay, Yusuf; Çoşut, Bünyemin; Zorlu, Yunus; Erkovan, Mustafa; Yerli, Yusuf

    2016-02-01

    A novel manganese (II) complex with picolinic acid (pyridine 2-carboxylic acid, Hpic), namely, [Mn(pic)2(H2O)2] was prepared and its crystal structure was fully characterized by using single crystal X-ray diffraction. Picolinate (pic) ligands were coordinated to the central manganese(II) ion as bidentate N,O-donors through the nitrogen atoms of pyridine rings and the oxygen atoms of carboxylate groups forming five-membered chelate rings. The spectroscopic characterization of Mn(II) complex was performed by the applications of FT-IR, Raman, UV-vis and EPR techniques. In order to support these studies, density functional theory (DFT) calculations were carried out by using B3LYP level. IR and Raman spectra were simulated at B3LYP level, and obtained results indicated that DFT calculations generally give compatible results to the experimental ones. The electronic structure of the Mn(II) complex was predicted using time dependent DFT (TD-DFT) method with polarizable continuum model (PCM). Molecular stability, hyperconjugative interactions, intramolecular charge transfer (ICT) and bond strength were investigated by applying natural bond orbital (NBO) analysis. Nonlinear optical properties of Mn(II) complex were investigated by the determining of molecular polarizability (α) and hyperpolarizability (β) parameters.

  7. Accelerometer-Based Navigation Is as Accurate as Optical Computer Navigation in Restoring the Joint Line and Mechanical Axis After Total Knee Arthroplasty: A Prospective Matched Study.

    PubMed

    Goh, Graham Seow-Hng; Liow, Ming Han Lincoln; Lim, Winston Shang-Rong; Tay, Darren Keng-Jin; Yeo, Seng Jin; Tan, Mann Hong

    2016-01-01

    The Zimmer iASSIST system is a novel accelerometer-based navigation system for TKA. 76 patients (76 knees) were prospectively matched for age, BMI, gender, diagnosis, and pre-operative scores, and underwent TKA using the iASSIST (n=38) or optical CAS (n=38). There were no significant differences in clinical outcomes or satisfaction rates at six months post-operatively (P>0.05). Mechanical axis was 1.8±1.3° in the iASSIST cohort versus 2.1±1.6° in the CAS cohort (P=0.543). There were no significant differences in number of outliers for mechanical axis (P=1.000), coronal femoral-component angle (P=0.693), coronal tibial-component angle (P=0.204) or joint line deviation (P=1.000). The duration of surgery was significantly longer in the CAS group (P<0.001), while the added cost of accelerometer-based navigation was approximately $1000 per operation.

  8. Single layer lead iodide: computational exploration of structural, electronic and optical properties, strain induced band modulation and the role of spin-orbital-coupling

    NASA Astrophysics Data System (ADS)

    Zhou, Mei; Duan, Wenhui; Chen, Ying; Du, Aijun

    Graphitic like layered materials exhibit intriguing electronic structures and the search for new types of two-dimensional (2D) monolayer materials is of great interest for developing novel nano-devices. By using density functional theory method, we investigate the structure, stability, electronic and optical properties of monolayer lead iodide (PbI2) . The stability of PbI2 monolayer is first confirmed by phonon dispersion calculation. Compared to the calculation using generalized gradient approximation, screened hybrid functional and spin-orbit coupling effects can predicts an accurate band gap (2.63 eV). The biaxial strain can tune its band gap size in a wide range from 1 eV to 3 eV, which can be understood by the strain induced uniformly change of electric field between Pb and I atomic layer. The calculated imaginary part of the dielectric function of 2D graphene/PbI2 van der Waals type hetero-structure shows significant red shift of absorption edge compared to that of a pure monolayer PbI2. Our findings highlight a new interesting 2D material with potential applications in nanoelectronics and optoelectronics.

  9. Films Containing Optically Nonlinear Diacetylene Monomer

    NASA Technical Reports Server (NTRS)

    Paley, Mark S.; Mcmanus, Samuel P.; Frazier, Donald O.

    1993-01-01

    Solid films exhibiting nonlinear optical properties prepared as mixtures of poly(methyl methacrylate) with various amounts of diacetylene monomer called "compound 1" in article, "Synthesizing Diacetylenes With Nonlinear Optical Properties" (MFS-26186). Useful as phase-conjugate mirrors in laser-beam communications and as optical switches in optical computers. This particular diacetylene monomer exhibits strong third-order nonlinear optical properties, both in pure form and in solution.

  10. Optical Symbolic Processor for Expert System Execution

    DTIC Science & Technology

    1987-11-30

    editions are obsolete. F. - 2 - 1. EXISTING OPTICAL SHUFFLE-EXCHANGE NETWORK DESIGNS There has been increasing interest recently in the implementation...resolution is incorporated in the switch depends on how the mask or the age of a message is encoded and updated. 3.2. Acousto - optic gate The acoutooptic gate...J. Seymour, ’ Optical Computing and the Fredkin Gates,’ Applied Optics , 15 May 1986. [9] R. Cuykendall and D . McMillin, ’Control-specific Optical

  11. Sensitivity of gas filter correlation instrument to variations in optical balance. [computer program simulated the response of the GFCR to changing pollutant levels

    NASA Technical Reports Server (NTRS)

    Orr, H. D., III; Campbell, S. A.

    1975-01-01

    A computer program was used to simulate the response of the Gas Filter Correlation Radiometer (GFCR) to changing pollutant levels of CO, SO2, CH4, and NH3 in two model atmospheres. Positive and negative deviations of tau sub alpha of magnitudes 0.01, 0.1, and 1 percent were imposed upon the simulation and the resulting deviations in inferred concentrations were determined. For the CO, CH4, and the higher pressure cell of the NH3 channel, the deviations are less than + or - 12 percent for deviations in tau sub alpha of + or - 0.1 percent, but increase to significantly higher values for larger deviations. For the lower pressure cell of NH3 and for SO2, the deviations in inferred concentration begin to rise sharply between 0.01 and 0.1 percent deviation in tau sub alpha, suggesting that a tighter control on tau sub alpha may be required for these channels.

  12. User's guide to HELIOS: A computer program for modeling the optical behavior of reflecting solar concentrators. Part 3: Appendices concerning HELIOS-code details

    NASA Astrophysics Data System (ADS)

    Vittitoe, C. N.; Biss, F.

    1981-09-01

    HELIOS is a flexible computer code for evaluating designs for central-receiver, parabolic-dish, and other reflecting solar-energy collector systems; for safety calculations on the threat to personnel and to the facility itself; for determination of how various input parameters alter the power collected; for design trade-offs; and for heliostat evaluations. Input variables include atmospheric transmission effects; reflector shape, surface, and suntracking errors; focusing and alignment strategies; receiver design; placement positions of the tower and mirrors; time-of-day and day-of-year for the calculation. Part III is a series of appendices giving code details for subroutine and function descriptions, how common blocks are used, sample jobstreams, and magnetic tape use within the code.

  13. Characterization of optically stimulated luminescence dosimeters and investigating their potential for estimating pediatric organ doses in multi-slice computed tomography

    NASA Astrophysics Data System (ADS)

    Al-Senan, Rani Mohammed

    Recent epidemiologic studies have shown a strong association between the relatively high doses of pediatric CT and the risk of cancer. Quantifying organ doses, as a measure of the risk, is commonly based on either direct anthropomorphic phantom measurements or Monte Carlo simulation. The major disadvantage in the phantom approach is its high cost especially that, for pediatric CT dosimetry, various phantom sizes are required to represent different age groups of children. On the other hand, Monte Carlo simulation, although not considered costly, requires validation by anthropomorphic phantom measurements. The aim of this project was to develop two methods of organ dose estimation in pediatric CT: 1) from the measured surface dose using optically stimulated luminescence dosimeters (OSLDs) and 2) by measuring the circumference of the body part being scanned as well as knowing the scan parameters. The project was based on a study proposed by the surgery department to monitor radiation exposure to children during their CT examination in the ER. A total of 200 pediatric patients were enrolled in this study which used OSLDs to monitor the doses. Specific aim 1 of this project was to characterize the OSLDs in the diagnostic energy range. Specific aim 2(a) was to find relationships between the patients' doses from OSLDs and both scan CTDI and the measured circumference. In specific aim 2(b) we carried out measurements using CTDI phantoms to investigate the relationships studied in specific aim 2(a). Specific aim 3 was to come up with models to estimate select organ doses from measuring surface dose or by using the circumference of the body part. To do this, pediatric examinations were simulated using a set of pediatric anthropomorphic phantoms in which doses of select organs were measured.

  14. Parallel Readout of Optical Disks

    DTIC Science & Technology

    1992-08-01

    computing , several types of neural networks including optical and optoelectronic neural networks, image classifiers, and image correlators. 14...memory with possibly a huge storage capacity. A " neural network is an example of a massively par- allel computer architecture that maps well to...image correlator and holograms stored on the disk may serve as interconnect patterns for hybrid optical/ VLSI based neural net- works. In this paper

  15. Computers for the Disabled.

    ERIC Educational Resources Information Center

    Lazzaro, Joseph J.

    1993-01-01

    Describes adaptive technology for personal computers that accommodate disabled users and may require special equipment including hardware, memory, expansion slots, and ports. Highlights include vision aids, including speech synthesizers, magnification, braille, and optical character recognition (OCR); hearing adaptations; motor-impaired…

  16. Computers and Copyrights: Bibliography.

    ERIC Educational Resources Information Center

    Kotlas, Carolyn, Comp.

    This bibliography lists sources of information to help college and university computer center staff to interpret copyright law as it relates to software, optical disks and other formats used in multimedia development and classroom presentations. The document is designed to be useful in answering faculty and student questions, formulating campus…

  17. Quantum optics, what next?

    NASA Astrophysics Data System (ADS)

    Cirac, J. Ignacio; Kimble, H. Jeff

    2017-01-01

    Quantum optics is a well-established field that spans from fundamental physics to quantum information science. In the coming decade, areas including computation, communication and metrology are all likely to experience scientific and technological advances supported by this far-reaching research field.

  18. COMPUTATIONAL MODELING OF THE CLASS I LOW-MASS PROTOSTAR ELIAS 29 APPLYING OPTICAL CONSTANTS OF ICES PROCESSED BY HIGH ENERGY COSMIC RAY ANALOGS

    SciTech Connect

    Rocha, W. R. M.; Pilling, S. E-mail: sergiopilling@yahoo.com.br

    2015-04-10

    We present a study of the effects of high energy cosmic rays (CRs) over the astrophysical ices, observed toward the embedded class I protostar Elias 29, by using computational modeling and laboratory data. Its spectrum was observed with the Infrared Space Observatory (ISO) covering 2.3–190 μm. The modeling employed the three-dimensional Monte Carlo radiative transfer code RADMC-3D and laboratory data of bombarded ice grains by CR analogs and unprocessed ices (not bombarded). We are assuming that Elias 29 has a self-irradiated disk with inclination i = 60.°0, surrounded by an envelope with a bipolar cavity. The results show that absorption features toward Elias 29 are better reproduced by assuming a combination between unprocessed astrophysical ices at low temperature (H{sub 2}O, CO, CO{sub 2}) and bombarded ices (H{sub 2}O:CO{sub 2}) by high energy CRs. Evidences of the ice processing around Elias 29 can be observed by the good fitting around 5.5–8.0 μm, by polar and apolar ice segregation in 15.15–15.25 μm, and by the presence of the CH{sub 4} and HCOOH ices. Given that non-nitrogen compounds were employed in this work, we assume that absorption around 5.5–8.0 μm should not be associated with the NH{sub 4}{sup +} ion (see the 2003 work of Shutte and Khanna ), but more probably with aliphatic ethers (e.g., R1-OCH{sub 2}-R2), CH{sub 3}CHO, and related species. The results obtained in this paper are important because they show that the environment around protostars is better modeled considering processed samples and, consequently, demonstrate the chemical evolution of the astrophysical ices.

  19. Computational Modeling of the Class I Low-Mass Protostar Elias 29 Applying Optical Constants of Ices Processed By High Energy Cosmic Ray Analogs

    NASA Astrophysics Data System (ADS)

    Rocha, W. R. M.; Pilling, S.

    2015-04-01

    We present a study of the effects of high energy cosmic rays (CRs) over the astrophysical ices, observed toward the embedded class I protostar Elias 29, by using computational modeling and laboratory data. Its spectrum was observed with the Infrared Space Observatory (ISO) covering 2.3-190 μm. The modeling employed the three-dimensional Monte Carlo radiative transfer code RADMC-3D and laboratory data of bombarded ice grains by CR analogs and unprocessed ices (not bombarded). We are assuming that Elias 29 has a self-irradiated disk with inclination i = 60.°0, surrounded by an envelope with a bipolar cavity. The results show that absorption features toward Elias 29 are better reproduced by assuming a combination between unprocessed astrophysical ices at low temperature (H2O, CO, CO2) and bombarded ices (H2O:CO2) by high energy CRs. Evidences of the ice processing around Elias 29 can be observed by the good fitting around 5.5-8.0 μm, by polar and apolar ice segregation in 15.15-15.25 μm, and by the presence of the CH4 and HCOOH ices. Given that non-nitrogen compounds were employed in this work, we assume that absorption around 5.5-8.0 μm should not be associated with the NH4+ ion (see the 2003 work of Shutte & Khanna ), but more probably with aliphatic ethers (e.g., R1-OCH2-R2), CH3CHO, and related species. The results obtained in this paper are important because they show that the environment around protostars is better modeled considering processed samples and, consequently, demonstrate the chemical evolution of the astrophysical ices.

  20. Optical microspectrometer

    DOEpatents

    Sweatt, William C.; Christenson, Todd R.

    2004-05-25

    An optical microspectrometer comprises a grism to disperse the spectra in a line object. A single optical microspectrometer can be used to sequentially scan a planar object, such as a dye-tagged microchip. Because the optical microspectrometer is very compact, multiple optical microspectrometers can be arrayed to provide simultaneous readout across the width of the planar object The optical microspectrometer can be fabricated with lithographic process, such as deep X-ray lithography (DXRL), with as few as two perpendicular exposures.

  1. Large-scale silicon optical switches for optical interconnection

    NASA Astrophysics Data System (ADS)

    Qiao, Lei; Tang, Weijie; Chu, Tao

    2016-11-01

    Large-scale optical switches are greatly demanded in building optical interconnections in data centers and high performance computers (HPCs). Silicon optical switches have advantages of being compact and CMOS process compatible, which can be easily monolithically integrated. However, there are difficulties to construct large ports silicon optical switches. One of them is the non-uniformity of the switch units in large scale silicon optical switches, which arises from the fabrication error and causes confusion in finding the unit optimum operation points. In this paper, we proposed a method to detect the optimum operating point in large scale switch with limited build-in power monitors. We also propose methods for improving the unbalanced crosstalk of cross/bar states in silicon electro-optical MZI switches and insertion losses. Our recent progress in large scale silicon optical switches, including 64 × 64 thermal-optical and 32 × 32 electro-optical switches will be introduced. To the best our knowledge, both of them are the largest scale silicon optical switches in their sections, respectively. The switches were fabricated on 340-nm SOI substrates with CMOS 180- nm processes. The crosstalk of the 32 × 32 electro-optic switch was -19.2dB to -25.1 dB, while the value of the 64 × 64 thermal-optic switch was -30 dB to -48.3 dB.

  2. Optically tunable optical filter

    NASA Astrophysics Data System (ADS)

    James, Robert T. B.; Wah, Christopher; Iizuka, Keigo; Shimotahira, Hiroshi

    1995-12-01

    We experimentally demonstrate an optically tunable optical filter that uses photorefractive barium titanate. With our filter we implement a spectrum analyzer at 632.8 nm with a resolution of 1.2 nm. We simulate a wavelength-division multiplexing system by separating two semiconductor laser diodes, at 1560 nm and 1578 nm, with the same filter. The filter has a bandwidth of 6.9 nm. We also use the same filter to take 2.5-nm-wide slices out of a 20-nm-wide superluminescent diode centered at 840 nm. As a result, we experimentally demonstrate a phenomenal tuning range from 632.8 to 1578 nm with a single filtering device.

  3. Fiber optic Adaline neural networks

    NASA Astrophysics Data System (ADS)

    Ghosh, Anjan K.; Trepka, Jim; Paparao, Palacharla

    1993-02-01

    Optoelectronic realization of adaptive filters and equalizers using fiber optic tapped delay lines and spatial light modulators has been discussed recently. We describe the design of a single layer fiber optic Adaline neural network which can be used as a bit pattern classifier. In our realization we employ as few electronic devices as possible and use optical computation to utilize the advantages of optics in processing speed, parallelism, and interconnection. The new optical neural network described in this paper is designed for optical processing of guided lightwave signals, not electronic signals. We analyzed the convergence or learning characteristics of the optically implemented Adaline in the presence of errors in the hardware, and we studied methods for improving the convergence rate of the Adaline.

  4. Computers and Computer Cultures.

    ERIC Educational Resources Information Center

    Papert, Seymour

    1981-01-01

    Instruction using computers is viewed as different from most other approaches to education, by allowing more than right or wrong answers, by providing models for systematic procedures, by shifting the boundary between formal and concrete processes, and by influencing the development of thinking in many new ways. (MP)

  5. Numerical Optimization Using Desktop Computers

    DTIC Science & Technology

    1980-09-11

    concentrating compound parabolic trough solar collector . Thermophysical, geophysical, optical and economic analyses were used to compute a life-cycle...third computer program, NISCO, was developed to model a nonimaging concentrating compound parabolic trough solar collector using thermophysical...concentrating compound parabolic trough Solar Collector . C. OBJECTIVE The objective of this thesis was to develop a system of interactive programs for the Hewlett

  6. EDITORIAL: Optical orientation Optical orientation

    NASA Astrophysics Data System (ADS)

    SAME ADDRESS *, Yuri; Landwehr, Gottfried

    2008-11-01

    radiation. The major results of the systematic work on optical orientation, both experimental and theoretical, at the Ioffe Institute and the Ecole Normale Supérieure in Paris are documented in the book Optical Orientation, edited by F Meier and B P Zakharchenya in the series Modern Problems in Condensed Matter Sciences [4], in which the foundations of optical orientation are comprehensively presented by renowned authors. This book is still the unsurpassed standard work in the field. If one asks what has become new since that publication in 1984 it is obviously the arrival of low-dimensional structures, two-dimensional heterostructures and zero-dimensional quantum dots. It has turned out that the quantum confinement can significantly modify the spin lifetime and the spin relaxation. The experimental work on spin alignment was done by a relative small number of researchers. However, the situation has substantially changed during the last decade. Research on spin-related phenomena has become very popular and the word 'spintronics' was coined. Spin research is no longer considered to be somewhat esoteric, since the replacement of silicon microelectronics based on the electron charge by spin-based electronics is being discussed. Whether these proposals can be realized remains to be seen. But one consequence has been a worldwide increase of high level basic research in spin phenomena. Another line of current research which has contributed to the popularity of spin-related research is quantum computing, based on spin-qubits. To be useful, solid state systems require long spin relaxation times and weak interaction with the environment. This is indispensable for low error rates. The difficulties in achieving these goals have been extensively discussed in the literature. Nowadays, because of the volume and diversity of spin-related work worldwide, a book on optical orientation like that edited by Meyer and Zakharchenya does not seem possible, so in this special issue of

  7. Radiation optic neuropathy

    SciTech Connect

    Kline, L.B.; Kim, J.Y.; Ceballos, R.

    1985-08-01

    Following surgery for pituitary adenoma, radiation therapy is an accepted treatment in reducing tumor recurrence. However, a potential therapeutic complication is delayed radionecrosis of perisellar neural structures, including the optic nerves and chiasm. This particular cause of visual loss, radiation optic neuropathy (RON), has not been emphasized in the ophthalmologic literature. Four cases of RON seen in the past five years are reported. Diagnostic criteria include: (1) acute visual loss (monocular or binocular), (2) visual field defects indicating optic nerve or chiasmal dysfunction, (3) absence of optic disc edema, (4) onset usually within three years of therapy (peak: 1-1 1/2 years), and (5) no computed tomographic evidence of visual pathway compression. Pathologic findings, differential diagnosis and therapy will be discussed in outlining the clinical profile of RON.

  8. Synthesis, vapor growth, polymerization, and characterization of thin films of novel diacetylene derivatives of pyrrole. The use of computer modeling to predict chemical and optical properties of these diacetylenes and poly(diacetylenes)

    NASA Technical Reports Server (NTRS)

    Paley, M. S.; Frazier, D. O.; Abeledeyem, H.; Mcmanus, S. P.; Zutaut, S. E.

    1992-01-01

    In the present work two diacetylene derivatives of pyrrole which are predicted by semiempirical AM1 calculations to have very different properties, are synthesized; the polymerizability of these diacetylenes in the solid state is determined, and the results are compared to the computer predictions. Diacetylene 1 is novel in that the monomer is a liquid at room temperature; this may allow for the possibility of polymerization in the liquid state as well as the solid state. Thin poly(diacetylene) films are obtained from compound 1 by growing films of the monomer using vapor deposition and polymerizing with UV light; these films are then characterized. Interestingly, while the poly(diacetylene) from 1 does not possess good nonlinear optical properties, the monomer exhibits very good third-order effects (phase conjugation) in solution. Dilute acetone solutions of the monomer 1 give intensity-dependent refractive indices on the order of 10 exp -6 esu; these are 10 exp 6 times better than for CS2.

  9. The Optics Option: Preparing For A Career In Optics

    NASA Astrophysics Data System (ADS)

    Hartmann, Rudolf

    1989-04-01

    . Exciting new fields, such as optical communication, optical computing, Phase conjugation, adaptive optics, and holography, are expanding the scope of optics technologies. Development of sophisticated military EO systems presents one of the greatest opportunities and challenges in the optics world today.

  10. Optical Solitons

    NASA Astrophysics Data System (ADS)

    Taylor, J. R.

    2005-08-01

    1. Optical solitons in fibres: theoretical review A. Hasegawa; 2. Solitons in optical fibres: an experimental account L. F. Mollenauer; 3. All-optical long-distance soliton-based transmission systems K. Smith and L. F. Mollenauer; 4. Nonlinear propagation effects in optical fibres: numerical studies K. J. Blow and N. J. Doran; 5. Soliton-soliton interactions C. Desem and P. L. Chu; 6. Soliton amplification in erbium-doped fibre amplifiers and its application to soliton communication M. Nakazawa; 7. Nonlinear transformation of laser radiation and generation of Raman solitons in optical fibres E. M. Dianov, A. B. Grudinin, A. M. Prokhorov and V. N. Serkin; 8. Generation and compression of femtosecond solitons in optical fibers P. V. Mamyshev; 9. Optical fibre solitons in the presence of higher order dispersion and birefringence C. R. Menyuk and Ping-Kong A. Wai; 10. Dark optical solitons A. M. Weiner; 11. Soliton Raman effects J. R. Taylor; Bibliography; Index.

  11. Optical Solitons

    NASA Astrophysics Data System (ADS)

    Taylor, J. R.

    1992-04-01

    1. Optical solitons in fibres: theoretical review A. Hasegawa; 2. Solitons in optical fibres: an experimental account L. F. Mollenauer; 3. All-optical long-distance soliton-based transmission systems K. Smith and L. F. Mollenauer; 4. Nonlinear propagation effects in optical fibres: numerical studies K. J. Blow and N. J. Doran; 5. Soliton-soliton interactions C. Desem and P. L. Chu; 6. Soliton amplification in erbium-doped fibre amplifiers and its application to soliton communication M. Nakazawa; 7. Nonlinear transformation of laser radiation and generation of Raman solitons in optical fibres E. M. Dianov, A. B. Grudinin, A. M. Prokhorov and V. N. Serkin; 8. Generation and compression of femtosecond solitons in optical fibers P. V. Mamyshev; 9. Optical fibre solitons in the presence of higher order dispersion and birefringence C. R. Menyuk and Ping-Kong A. Wai; 10. Dark optical solitons A. M. Weiner; 11. Soliton Raman effects J. R. Taylor; Bibliography; Index.

  12. Optical probe

    DOEpatents

    Hencken, Kenneth; Flower, William L.

    1999-01-01

    A compact optical probe is disclosed particularly useful for analysis of emissions in industrial environments. The instant invention provides a geometry for optically-based measurements that allows all optical components (source, detector, rely optics, etc.) to be located in proximity to one another. The geometry of the probe disclosed herein provides a means for making optical measurements in environments where it is difficult and/or expensive to gain access to the vicinity of a flow stream to be measured. Significantly, the lens geometry of the optical probe allows the analysis location within a flow stream being monitored to be moved while maintaining optical alignment of all components even when the optical probe is focused on a plurality of different analysis points within the flow stream.

  13. Computer Music

    NASA Astrophysics Data System (ADS)

    Cook, Perry R.

    This chapter covers algorithms, technologies, computer languages, and systems for computer music. Computer music involves the application of computers and other digital/electronic technologies to music composition, performance, theory, history, and the study of perception. The field combines digital signal processing, computational algorithms, computer languages, hardware and software systems, acoustics, psychoacoustics (low-level perception of sounds from the raw acoustic signal), and music cognition (higher-level perception of musical style, form, emotion, etc.).

  14. Optical keyboard

    DOEpatents

    Veligdan, James T.; Feichtner, John D.; Phillips, Thomas E.

    2001-01-01

    An optical keyboard includes an optical panel having optical waveguides stacked together. First ends of the waveguides define an inlet face, and opposite ends thereof define a screen. A projector transmits a light beam outbound through the waveguides for display on the screen as a keyboard image. A light sensor is optically aligned with the inlet face for sensing an inbound light beam channeled through the waveguides from the screen upon covering one key of the keyboard image.

  15. Computer Music

    NASA Astrophysics Data System (ADS)

    Cook, Perry

    This chapter covers algorithms, technologies, computer languages, and systems for computer music. Computer music involves the application of computers and other digital/electronic technologies to music composition, performance, theory, history, and perception. The field combines digital signal processing, computational algorithms, computer languages, hardware and software systems, acoustics, psychoacoustics (low-level perception of sounds from the raw acoustic signal), and music cognition (higher-level perception of musical style, form, emotion, etc.). Although most people would think that analog synthesizers and electronic music substantially predate the use of computers in music, many experiments and complete computer music systems were being constructed and used as early as the 1950s.

  16. Highly Non-Linear Optical (NLO) organic crystals and films. Electrooptical organic materials

    NASA Technical Reports Server (NTRS)

    Mcmanus, Samuel P.; Rosenberger, Franz; Matthews, John

    1987-01-01

    Devices employing nonlinear optics (NLO) hold great promise for important applications in integrated optics, optical information processing and telecommunications. Properly designed organics possess outstanding optical and electrooptical properties which will substantially advance many technologies including electrooptical switching, optical amplification for communications, and parallel processing for hybrid optical computers. A brief comparison of organic and inorganic materials is given.

  17. UltraScale Computing

    NASA Astrophysics Data System (ADS)

    Maynard, , Jr.

    1997-08-01

    The Defense Advanced Research Projects Agency Information Technology Office (DARPA/ITO) supports research in technology for defense-critical applications. Defense Applications are always insatiable consumers of computing. Futuristic applications such as automated image interpretation/whole vehicle radar-cross-section/real-time prototyping/faster-than-real-time simulation will require computing capabilities orders-of-magnitude beyond the best performance that can be projected from contemporary scalable parallel processors. To reach beyond the silicon digital paradigm, DARPA has initiated a program in UltraScale Computing to explore the domain of innovative computational models, methods, and mechanisms. The objective is to encourage a complete re-thinking of computing. Novel architectures, program synthesis, and execution environments are needed as well as alternative underlying physical mechanisms including molecular, biological, optical and quantum mechanical processes. Development of these advanced computing technologies will offer spectacular performance and cost improvements beyond the threshold of traditional materials and processes. The talk will focus on novel approaches for employing vastly more computational units than shrinking transistors will enable and exploration of the biological options for solving computationally difficult problems.

  18. Optic nerve hypoplasia: septo-optic-pituitary dysplasia syndrome.

    PubMed Central

    Acers, T E

    1981-01-01

    Forty-five patients with the common clinical factor of optic nerve hypoplasia are analyzed regarding their clinical appearance, echographic and computed tomographic measurements of the optic nerves, and the correlation of anatomic size with visual function. Computed axial tomographic studies of the midline brain were performed on all 45 patients to determine the incidence of correlated structural defects, especially the septum pellucidum, and neuroendocrine dysfunction. Review of the spectrum of septo-optic-pituitary syndrome is separately developed to include historical background, embryogenesis, histopathology, and pathogenesis of the three major components of the syndrome. In summary, 45 patients had optic nerve hypoplasia, 32 with evidence of segmental or partial hypoplasia and 13 with evidence of complete or diffuse hypoplasia--the optic nerve hypoplasia syndrome. Twelve of these patients demonstrated absence of the septum pellucidum by computed axial tomography--the septo-optic dysplasia syndrome. Of these 12 patients with partial or complete absence of the septum pellucidum, six demonstrated evidence of pituitary hypofunction--the septo-optic-pituitary dysplasia syndrome. Images FIGURE 2 FIGURE 3 a FIGURE 3 b FIGURE 4 a FIGURE 4 b FIGURE 4 c FIGURE 4 d PMID:7043865

  19. Fluidic optics

    NASA Astrophysics Data System (ADS)

    Whitesides, George M.; Tang, Sindy K. Y.

    2006-09-01

    Fluidic optics is a new class of optical system with real-time tunability and reconfigurability enabled by the introduction of fluidic components into the optical path. We describe the design, fabrication, operation of a number of fluidic optical systems, and focus on three devices, liquid-core/liquid-cladding (L2) waveguides, microfluidic dye lasers, and diffraction gratings based on flowing, crystalline lattices of bubbles, to demonstrate the integration of microfluidics and optics. We fabricate these devices in poly(dimethylsiloxane) (PDMS) with soft-lithographic techniques. They are simple to construct, and readily integrable with microanalytical or lab-on-a-chip systems.

  20. Education of optics with Matlab

    NASA Astrophysics Data System (ADS)

    Miks, Antonin; Novak, Jiri

    2003-11-01

    In our work there is shown one of possible approaches to education of various parts of optics with a mathematical system MATLAB. The work is focused mainly on education of interference and diffraction of light and the diffraction theory of optical imaging. In our laboratories students can simply perform a computer simulation of various problems, which they can meet in practice, e.g. two-beam interferometry, imaging in coherent, partially coherent or incoherent light, diffraction from gratings of different types, etc. The system Matlab can be also used for simulating problems in holography and holographic interferometry of static and dynamic events. Students can further simulate transforming of optical beams through a simple lens or a system of lenses by means of ray tracing. For every described part of optics we have the software programmed in the Matlab system. Matlab seems to be a very good tool for numerical modelling of properties of various optical systems and for teaching optics.

  1. Optic Nerve.

    PubMed

    Gordon, Lynn K

    2016-10-28

    Optic nerve diseases arise from many different etiologies including inflammatory, neoplastic, genetic, infectious, ischemic, and idiopathic. Understanding some of the characteristics of the most common optic neuropathies along with therapeutic approaches to these diseases is helpful in designing recommendations for individual patients. Although many optic neuropathies have no specific treatment, some do, and it is those potentially treatable or preventable conditions which need to be recognized in order to help patients regain their sight or develop a better understanding of their own prognosis. In this chapter several diseases are discussed including idiopathic intracranial hypertension, optic neuritis, ischemic optic neuropathies, hereditary optic neuropathies, trauma, and primary tumors of the optic nerve. For each condition there is a presentation of the signs and symptoms of the disease, in some conditions the evaluation and diagnostic criteria are highlighted, and where possible, current therapy or past trials are discussed.

  2. Cooling Computers.

    ERIC Educational Resources Information Center

    Birken, Marvin N.

    1967-01-01

    Numerous decisions must be made in the design of computer air conditioning, each determined by a combination of economics, physical, and esthetic characteristics, and computer requirements. Several computer air conditioning systems are analyzed--(1) underfloor supply and overhead return, (2) underfloor plenum and overhead supply with computer unit…

  3. Pygmalion's Computer.

    ERIC Educational Resources Information Center

    Peelle, Howard A.

    Computers have undoubtedly entered the educational arena, mainly in the areas of computer-assisted instruction (CAI) and artificial intelligence, but whether educators should embrace computers and exactly how they should use them are matters of great debate. The use of computers in support of educational administration is widely accepted.…

  4. Optical Computations for Image Bandwidth Compression.

    DTIC Science & Technology

    1982-05-15

    of Contents Page (I) Report Documentation Page 1 (II) Disclaimer 2 (III) Introduction 3 (IV) List of Publications Resulting from AFOSR Support 4 (V...sampled data. App’ndix Contents : This appendix consists of a summary of the research in this area as directly evaluated to date, plus a paper on...window location, the center sample, plus estimates of the other three bands formed from the window content , are written to the corresponding spatial

  5. Towards Quantum Computing With Light

    NASA Astrophysics Data System (ADS)

    Pysher, Matthew

    This thesis presents experimental progress towards the realization of an optical quantum computer. Quantum computers replace the bits used in classical computing with quantum systems and promise an exponential speedup over their classical counterparts for certain tasks such as integer factoring and the simulation of quantum systems. A recently proposed quantum computing protocol known as one-way quantum computing has paved the way for the use of light in a functional quantum computer. One-way quantum computing calls for the generation of a large (consisting of many subsystems) entangled state known as a cluster state to serve as a quantum register. Entangled states are comprised of subsystems linked in such a way that the state cannot be separated into individual components. A recent proposal has shown that is possible to make arbitrarily large cluster states by linking the resonant frequency modes of a single optical parametric oscillator (OPO). In this thesis, we present two major steps towards the creation of such a cluster state. Namely, we successfully design and test the exotic nonlinear crystal needed in this proposal and use a slight variation on this proposal to simultaneously create over 15 four-mode cluster states in a single OPO. We also explore the possibility of scaling down the physical size of an optical quantum computer by generating squeezed states of light in a compact optical waveguide. Additionally, we investigate photon-number-resolving measurements on continuous quantum light sources, which will be necessary to obtain the desired speedups for a quantum computer over a classical computer.

  6. Optical solver of combinatorial problems: nanotechnological approach.

    PubMed

    Cohen, Eyal; Dolev, Shlomi; Frenkel, Sergey; Kryzhanovsky, Boris; Palagushkin, Alexandr; Rosenblit, Michael; Zakharov, Victor

    2013-09-01

    We present an optical computing system to solve NP-hard problems. As nano-optical computing is a promising venue for the next generation of computers performing parallel computations, we investigate the application of submicron, or even subwavelength, computing device designs. The system utilizes a setup of exponential sized masks with exponential space complexity produced in polynomial time preprocessing. The masks are later used to solve the problem in polynomial time. The size of the masks is reduced to nanoscaled density. Simulations were done to choose a proper design, and actual implementations show the feasibility of such a system.

  7. Solitonic Gateless Computing

    DTIC Science & Technology

    2006-01-29

    logic functions and mathematical operations were implemented in the laboratory based on soliton collisions in photorefractive media. In addition to...the usual NAND and AND logic gates, soliton collisions do transfer information and two successive collisions can be made to mimic a unitary matrix or...clear proof-of- principle for soliton based optical computing functions , electronics has advanced in speed and power requirements in the last six years

  8. Nonlinear optical thin films

    NASA Technical Reports Server (NTRS)

    Leslie, Thomas M.

    1993-01-01

    A focused approach to development and evaluation of organic polymer films for use in optoelectronics is presented. The issues and challenges that are addressed include: (1) material synthesis, purification, and the tailoring of the material properties; (2) deposition of uniform thin films by a variety of methods; (3) characterization of material physical properties (thermal, electrical, optical, and electro-optical); and (4) device fabrication and testing. Photonic materials, devices, and systems were identified as critical technology areas by the Department of Commerce and the Department of Defense. This approach offers strong integration of basic material issues through engineering applications by the development of materials that can be exploited as the active unit in a variety of polymeric thin film devices. Improved materials were developed with unprecedented purity and stability. The absorptive properties can be tailored and controlled to provide significant improvement in propagation losses and nonlinear performance. Furthermore, the materials were incorporated into polymers that are highly compatible with fabrication and patterning processes for integrated optical devices and circuits. By simultaneously addressing the issues of materials development and characterization, keeping device design and fabrication in mind, many obstacles were overcome for implementation of these polymeric materials and devices into systems. We intend to considerably improve the upper use temperature, poling stability, and compatibility with silicon based devices. The principal device application that was targeted is a linear electro-optic modulation etalon. Organic polymers need to be properly designed and coupled with existing integrated circuit technology to create new photonic devices for optical communication, image processing, other laser applications such as harmonic generation, and eventually optical computing. The progression from microscopic sample to a suitable film

  9. Gradient-Index Optics

    DTIC Science & Technology

    2010-03-31

    results. We now present three examples of ray paths computed by solving Eq. (3) numerically using a standard fixed-step Runge - Kutta method . We also...Associates. The nonimaging design approach looked to generalize established techniques of advanced nonimaging optical design, such as the edge-ray method ...the simultaneous multiple-surface (SMS) method , global optimization, and the recent SAIC- developed generalized functional (GF) method . We have

  10. Optical Hidden Layer Networks

    DTIC Science & Technology

    1991-07-01

    List of Figures 1. Schematic for holographic Adaline learning. 2 2. Fiber optic acoustic transducer. 4 3. The storage of the Fourier transform of...modulator. The object of this experiment was to perform what is known as Adaline learning on a set of input vectors. In this task, one has a desired...ll ll! I Computer Figure I Schematic for holographic Adaline learning. In the course of our experiments we found that in practice our system

  11. Quantum computation for quantum chemistry

    NASA Astrophysics Data System (ADS)

    Aspuru-Guzik, Alan

    2010-03-01

    Numerically exact simulation of quantum systems on classical computers is in general, an intractable computational problem. Computational chemists have made progress in the development of approximate methods to tackle complex chemical problems. The downside of these approximate methods is that their failure for certain important cases such as long-range charge transfer states in the case of traditional density functional theory. In 1982, Richard Feynman suggested that a quantum device should be able to simulate quantum systems (in our case, molecules) exactly using quantum computers in a tractable fashion. Our group has been working in the development of quantum chemistry algorithms for quantum devices. In this talk, I will describe how quantum computers can be employed to carry out numerically exact quantum chemistry and chemical reaction dynamics calculations, as well as molecular properties. Finally, I will describe our recent experimental quantum computation of the energy of the hydrogen molecule using an optical quantum computer.

  12. Formal analysis of electromagnetic optics

    NASA Astrophysics Data System (ADS)

    Khan-Afshar, Sanaz; Hasan, Osman; Tahar, Sofiène

    2014-09-01

    Optical systems are increasingly being used in safety-critical applications. Due to the complexity and sensitivity of optical systems, their verification raises many challenges for engineers. Traditionally, the analysis of such systems has been carried out by paper-and-pencil based proofs and numerical computations. However, these techniques cannot provide accurate results due to the risk of human error and inherent approximations of numerical algorithms. In order to overcome these limitations, we propose to use theorem proving (i.e., a computer-based technique that allows to express mathematical expressions and reason about their correctness by taking into account all the details of mathematical reasoning) as a complementary approach to improve optical system analysis. This paper provides a higher-order logic (a language used to express mathematical theories) formalization of electromagnetic optics in the HOL Light theorem prover. In order to demonstrate the practical effectiveness of our approach, we present the analysis of resonant cavity enhanced photonic devices.

  13. Investigation of uses of holographic optical elements

    NASA Technical Reports Server (NTRS)

    Zech, R. G.; Latta, J. N.

    1973-01-01

    The data represent a thorough study of the aberrations and imaging properties of holographic optical elements. Principle studies include (1) the indepth experimental investigation of single holographic optical elements, (2) the verification of the accuracy of the theoretical computer-based description of hologram behavior, (3) the computer-generation of interferograms that are characteristic of a prescribed aberrated imaging condition, (4) the experimental verification of wavelength optimization, (5) the experimental determination of the space bandwidth product of single holographic optical elements as a function of bending and field angle, and (6) the first experimental study of the aberration properties of holographic optical elements constructed in very thick (750 microns) recording media.

  14. Optical Metacages

    NASA Astrophysics Data System (ADS)

    Mirzaei, Ali; Miroshnichenko, Andrey E.; Shadrivov, Ilya V.; Kivshar, Yuri S.

    2015-11-01

    We suggest a novel strategy for spectrally selective optical shielding of arbitrary shaped volumes by arranging specifically designed two- or three-layer nanowires around an area that needs to be protected. We show that such nanowire shields preserve their functionality for almost arbitrary geometry, and we term such structures optical metacages. We analyze several designs of such optical metacages made from either metallic or dielectric materials with experimentally measured parameters. We employ a semianalytical approach and also verify our results by numerical simulations. We further study optical properties of the introduced metacages in both near- and far-field regions, as well as analyze their frequency selectivity and the vanishing backscattering regime.

  15. Optical engineering

    SciTech Connect

    Saito, T T

    1998-01-01

    The Optical Engineering thrust area at Lawrence Livermore National Laboratory (LLNL) was created in the summer of 1996 with the following main objectives: (1) to foster and stimulate leading edge optical engineering research and efforts key to carrying out LLNL's mission and enabling major new programs; (2) to bring together LLNL's broad spectrum of high level optical engineering expertise to support its programs. Optical engineering has become a pervasive and key discipline, with applications across an extremely wide range of technologies, spanning the initial conception through the engineering refinements to enhance revolutionary application. It overlaps other technologies and LLNL engineering thrust areas.

  16. Optical trapping

    PubMed Central

    Neuman, Keir C.; Block, Steven M.

    2006-01-01

    Since their invention just over 20 years ago, optical traps have emerged as a powerful tool with broad-reaching applications in biology and physics. Capabilities have evolved from simple manipulation to the application of calibrated forces on—and the measurement of nanometer-level displacements of—optically trapped objects. We review progress in the development of optical trapping apparatus, including instrument design considerations, position detection schemes and calibration techniques, with an emphasis on recent advances. We conclude with a brief summary of innovative optical trapping configurations and applications. PMID:16878180

  17. Computational dosimetry

    SciTech Connect

    Siebert, B.R.L.; Thomas, R.H.

    1996-01-01

    The paper presents a definition of the term ``Computational Dosimetry`` that is interpreted as the sub-discipline of computational physics which is devoted to radiation metrology. It is shown that computational dosimetry is more than a mere collection of computational methods. Computational simulations directed at basic understanding and modelling are important tools provided by computational dosimetry, while another very important application is the support that it can give to the design, optimization and analysis of experiments. However, the primary task of computational dosimetry is to reduce the variance in the determination of absorbed dose (and its related quantities), for example in the disciplines of radiological protection and radiation therapy. In this paper emphasis is given to the discussion of potential pitfalls in the applications of computational dosimetry and recommendations are given for their avoidance. The need for comparison of calculated and experimental data whenever possible is strongly stressed.

  18. Computational Toxicology

    EPA Science Inventory

    Computational toxicology’ is a broad term that encompasses all manner of computer-facilitated informatics, data-mining, and modeling endeavors in relation to toxicology, including exposure modeling, physiologically based pharmacokinetic (PBPK) modeling, dose-response modeling, ...

  19. Cloud Computing

    SciTech Connect

    Pete Beckman and Ian Foster

    2009-12-04

    Chicago Matters: Beyond Burnham (WTTW). Chicago has become a world center of "cloud computing." Argonne experts Pete Beckman and Ian Foster explain what "cloud computing" is and how you probably already use it on a daily basis.

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

    SciTech Connect

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

    1995-08-10

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